This document summarizes five oxidation processes for wastewater treatment: cavitation, photocatalytic oxidation, Fenton's chemistry, ozonation, and hydrogen peroxide. It discusses the basics of each process, including optimal operating parameters and reactor design. The processes generate hydroxyl radicals that can oxidize many organic and inorganic compounds. While individually the processes can partially degrade compounds, a hybrid approach may be needed to fully treat wastewater and reduce toxicity to levels for further biological treatment. More research is still needed to scale up some technologies.
This document presents a study that used sonication (ultrasound) to remediate soil contaminated with 2-methylpropane-2-thiol. A central composite design and response surface methodology were used to model and optimize the effects of sonication power, time, and water content on removal efficiency. The model showed that power and time had the greatest effects on removal efficiency. Under optimal conditions of high power and long sonication time with a lower water content, a maximum removal efficiency of 82.83% was achieved.
The document summarizes research on using activated carbon prepared from olive stone waste to sorb copper, zinc, and nickel ions from aqueous solutions. Olive stone activated carbon (OSAC) was prepared under different physical activation conditions and characterized. OSAC-3, activated at 900°C for 3.5 hours, had the highest surface area and was selected for further study. Batch experiments were conducted to determine optimum sorption conditions and kinetics. The maximum sorption capacities were 25.38 mg/g for Cu2+, 16.95 mg/g for Zn2+, and 14.65 mg/g for Ni2+. Sorption was best described by pseudo-second order kinetics and was spontaneous and endothermic/exothermic
The radiolytic mineralization of 2-mercaptobenzothiazole, an emerging contami...IRJESJOURNAL
Abstract:The ability of high-energy ionizing radiation has been demonstrated for environmental remediation processing. γ-rayswere applied to treat a solution of 2-mercaptobenzothiazole (2-MBT). 2-MBT (125 µM) was decomposed and mineralized by the γ-radiation. The absorbed doses for 50 and 90% 2-MBT degradation were 0.170 and 0.650 kGy, respectively. Organic by-products were almost fully mineralized when high-absorbed doses in the range of 5-60 kGy were applied. Sulfate radicals (SO4 ●– ) produced through the rapid reaction of persulfate ions (S2O8 2– ) with hydrated electrons(eaq − ; keaq − /S2O8 2– = 1.1 × 1010 M −1 .s−1 ) had a significant effect on the 2-MBT mineralization yield. Because of 2-MBT decomposition,sulfate ions (SO4 2− ) were formed, and thepH and dissolved oxygen concentration were decreased. The degradation efficiency decreased when HCO3 –was added to the 2- MBT solution. No significant effects of NO3 – and Cl– ions on 2-MBT radiolytic eliminationwere observed
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Treatment of matchbox industry waste water by solar photo-fenton K.MAHESH KUMAR
The document discusses the treatment of wastewater from match box industries using the solar photo-Fenton process. Match box production generates wastewater high in biochemical oxygen demand, chemical oxygen demand, suspended solids, toxicity and color. The solar photo-Fenton process uses sunlight, ferrous ions, and hydrogen peroxide to degrade pollutants in the wastewater. Experiments found that a pH of 5, 1 g/L ferrous ions, 5 ml/L hydrogen peroxide, and a reaction time of 1 hour removed 92% of chemical oxygen demand from the wastewater. Liquid depth also influenced degradation rates, with shallower depths producing faster rates. The solar photo-Fenton process coupled with
This study examined the bioregeneration of granular activated carbon (GAC) contaminated with hydrocarbon using Pseudomonas putida bacteria. The rate of bioregeneration was analyzed by varying the volume of bacteria from 10-40ml and the temperature from 25-45°C over 21 days. Increasing the bacteria volume and temperature both increased the rate of bioregeneration. The highest regeneration efficiency occurred with 40ml of bacteria at 40°C, as increasing temperature further to 45°C did not provide additional benefit. Characterization of the GAC before and after regeneration showed that its properties were largely preserved through the bioregeneration process.
A Review on Applicability of Photocatalyst Titanium dioxide for Treatment of ...IJERA Editor
Greywater reuse has attracted great attention for sustainable management of water especially under water
scarcity conditions. However, the effort has been limited by the presence of toxic organics in the effluent which
in turn inhibits the public acceptance of recycling water. The existence of those organic pollutants, which cannot
be eliminated by conventional primary and secondary treatment processes, can be problematic. Hence it is
necessary to explore a sustainable, robust and affordable method for treatment of greywater. Photocatalytic
oxidation is an emerging technology that could be suitable to remove refractory organic compounds found in
greywater. Recently titanium dioxide (TiO2) gained wide attention for photocatalytic oxidation of organic matter
of wastewater. Because it is biologically and chemical inert, resistant to chemical corrosion and can work at
ambient temperature and pressure, without addition of chemical species. The irradiation of titanium dioxide
dispersions by ultraviolet (UV) (300-400 nm) light can lead to the formulation of highly reactive hydroxyl
radicals which attack the pollutant molecule to degrade it into carbon dioxide, water and mineral acids.This
technology has advantages, such as, the integration into small places, low maintenance and easy operation.
COD reduction of aromatic polluted waste water by Advanced Oxidation Process ...Wade Bitaraf
In most petrochemical complexes and oil refineries the wastewater contains the aromatic compounds among which Benzene, Toluene, Ethyl Benzene and Xylene (BTEX) have harmful effects on environment and human health. The present work mainly deals with the UV-based advanced oxidation processes (AOPs), UV/H2O2 were tested in batch reactor systems to evaluate the removal efficiencies and optimal conditions for the photodegradation of BTEX in order to wastewater treatment. The efficiency of this method was analyzed by evaluating the Chemical Oxygen Demand (COD) as a pollution criterion through the COD reactor. The influence of the basic operational parameters such as initial concentration of H2O2, pH, Temperature, irradiation time and UV amount on the photo degradation of BTEX were also studied. The oxidation rate of BTEX and respectively the reduction rate of COD were low when the oxidation was carried out in the absence of H2O2 or UV light. The addition of proper amount of hydrogen peroxide improved the degradation, while the excess hydrogen peroxide could quench the formation of hydroxyl radicals (•OH). The optimal conditions of suspended slurry with 1.11(g/l) initial concentration of H2O2 and pH value of 3.1 were obtained under three UV lights illumination (6 W). Under the optimal conditions, COD reduction during the initial period of 180 min in UV/H2O2 systems reached about 90%.
This document presents a study that used sonication (ultrasound) to remediate soil contaminated with 2-methylpropane-2-thiol. A central composite design and response surface methodology were used to model and optimize the effects of sonication power, time, and water content on removal efficiency. The model showed that power and time had the greatest effects on removal efficiency. Under optimal conditions of high power and long sonication time with a lower water content, a maximum removal efficiency of 82.83% was achieved.
The document summarizes research on using activated carbon prepared from olive stone waste to sorb copper, zinc, and nickel ions from aqueous solutions. Olive stone activated carbon (OSAC) was prepared under different physical activation conditions and characterized. OSAC-3, activated at 900°C for 3.5 hours, had the highest surface area and was selected for further study. Batch experiments were conducted to determine optimum sorption conditions and kinetics. The maximum sorption capacities were 25.38 mg/g for Cu2+, 16.95 mg/g for Zn2+, and 14.65 mg/g for Ni2+. Sorption was best described by pseudo-second order kinetics and was spontaneous and endothermic/exothermic
The radiolytic mineralization of 2-mercaptobenzothiazole, an emerging contami...IRJESJOURNAL
Abstract:The ability of high-energy ionizing radiation has been demonstrated for environmental remediation processing. γ-rayswere applied to treat a solution of 2-mercaptobenzothiazole (2-MBT). 2-MBT (125 µM) was decomposed and mineralized by the γ-radiation. The absorbed doses for 50 and 90% 2-MBT degradation were 0.170 and 0.650 kGy, respectively. Organic by-products were almost fully mineralized when high-absorbed doses in the range of 5-60 kGy were applied. Sulfate radicals (SO4 ●– ) produced through the rapid reaction of persulfate ions (S2O8 2– ) with hydrated electrons(eaq − ; keaq − /S2O8 2– = 1.1 × 1010 M −1 .s−1 ) had a significant effect on the 2-MBT mineralization yield. Because of 2-MBT decomposition,sulfate ions (SO4 2− ) were formed, and thepH and dissolved oxygen concentration were decreased. The degradation efficiency decreased when HCO3 –was added to the 2- MBT solution. No significant effects of NO3 – and Cl– ions on 2-MBT radiolytic eliminationwere observed
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Treatment of matchbox industry waste water by solar photo-fenton K.MAHESH KUMAR
The document discusses the treatment of wastewater from match box industries using the solar photo-Fenton process. Match box production generates wastewater high in biochemical oxygen demand, chemical oxygen demand, suspended solids, toxicity and color. The solar photo-Fenton process uses sunlight, ferrous ions, and hydrogen peroxide to degrade pollutants in the wastewater. Experiments found that a pH of 5, 1 g/L ferrous ions, 5 ml/L hydrogen peroxide, and a reaction time of 1 hour removed 92% of chemical oxygen demand from the wastewater. Liquid depth also influenced degradation rates, with shallower depths producing faster rates. The solar photo-Fenton process coupled with
This study examined the bioregeneration of granular activated carbon (GAC) contaminated with hydrocarbon using Pseudomonas putida bacteria. The rate of bioregeneration was analyzed by varying the volume of bacteria from 10-40ml and the temperature from 25-45°C over 21 days. Increasing the bacteria volume and temperature both increased the rate of bioregeneration. The highest regeneration efficiency occurred with 40ml of bacteria at 40°C, as increasing temperature further to 45°C did not provide additional benefit. Characterization of the GAC before and after regeneration showed that its properties were largely preserved through the bioregeneration process.
A Review on Applicability of Photocatalyst Titanium dioxide for Treatment of ...IJERA Editor
Greywater reuse has attracted great attention for sustainable management of water especially under water
scarcity conditions. However, the effort has been limited by the presence of toxic organics in the effluent which
in turn inhibits the public acceptance of recycling water. The existence of those organic pollutants, which cannot
be eliminated by conventional primary and secondary treatment processes, can be problematic. Hence it is
necessary to explore a sustainable, robust and affordable method for treatment of greywater. Photocatalytic
oxidation is an emerging technology that could be suitable to remove refractory organic compounds found in
greywater. Recently titanium dioxide (TiO2) gained wide attention for photocatalytic oxidation of organic matter
of wastewater. Because it is biologically and chemical inert, resistant to chemical corrosion and can work at
ambient temperature and pressure, without addition of chemical species. The irradiation of titanium dioxide
dispersions by ultraviolet (UV) (300-400 nm) light can lead to the formulation of highly reactive hydroxyl
radicals which attack the pollutant molecule to degrade it into carbon dioxide, water and mineral acids.This
technology has advantages, such as, the integration into small places, low maintenance and easy operation.
COD reduction of aromatic polluted waste water by Advanced Oxidation Process ...Wade Bitaraf
In most petrochemical complexes and oil refineries the wastewater contains the aromatic compounds among which Benzene, Toluene, Ethyl Benzene and Xylene (BTEX) have harmful effects on environment and human health. The present work mainly deals with the UV-based advanced oxidation processes (AOPs), UV/H2O2 were tested in batch reactor systems to evaluate the removal efficiencies and optimal conditions for the photodegradation of BTEX in order to wastewater treatment. The efficiency of this method was analyzed by evaluating the Chemical Oxygen Demand (COD) as a pollution criterion through the COD reactor. The influence of the basic operational parameters such as initial concentration of H2O2, pH, Temperature, irradiation time and UV amount on the photo degradation of BTEX were also studied. The oxidation rate of BTEX and respectively the reduction rate of COD were low when the oxidation was carried out in the absence of H2O2 or UV light. The addition of proper amount of hydrogen peroxide improved the degradation, while the excess hydrogen peroxide could quench the formation of hydroxyl radicals (•OH). The optimal conditions of suspended slurry with 1.11(g/l) initial concentration of H2O2 and pH value of 3.1 were obtained under three UV lights illumination (6 W). Under the optimal conditions, COD reduction during the initial period of 180 min in UV/H2O2 systems reached about 90%.
Industrial wastewater treatment via photocatalysisJay Lakhani
This document discusses using photocatalysis for industrial wastewater treatment. Specifically, it examines using ZnO nanoparticles as a photocatalyst coated on a support material. An experimental setup involved circulating 1.5 liters of textile wastewater through a ZnO coated reactor for 4 hours under solar radiation. Various parameters that affect the wastewater treatment were studied, including temperature, dye concentration, reaction time, pH and TOC variation over time. Results showed ZnO was more effective than TiO2 at degrading pollutants like COD. However, issues with ZnO include photocorrosion and difficulty recovering the nanoparticles from water. Overall, photocatalysis shows potential as a green technology for treating industrial wastewater
Development of an experimental rig for bioremediation studiesAlexander Decker
The document describes the development of an experimental rig for bioremediation studies using indigenous technology. Key details include:
- The rig consists of various units like air pretreatment, fixed bed bioreactors, volatile organic compound traps, air flow meter, and carbon dioxide traps.
- Components were sized, designed, and fabricated locally at low cost. Testing showed the rig effectively degraded 75% of oil and grease from contaminated soil over 10 weeks.
- The rig was used to study bioremediation of soil contaminated with spent motor oil in 6 treatments with various additives over room temperature.
The document summarizes advanced oxidation processes (AOPs) for treating food industry wastewater. It discusses four main AOP groups - electrochemical oxidation, Fenton's process, ozonation, and photocatalytic processes. All generate highly reactive hydroxyl radicals to degrade organic pollutants that are resistant to biological treatment. Electrochemical oxidation uses electrodes to produce hydroxyl radicals and has effectively treated various food industry wastewaters. Fenton's process uses ferrous ions and hydrogen peroxide to catalytically produce hydroxyl radicals. Photocatalytic processes employ materials like TiO2 and UV light to generate radicals.
This document compares the synthesis of oximes using traditional chemical methods versus ultrasonic irradiation. Oximes are important organic intermediates. The traditional method involves refluxing carbonyl compounds with hydroxylamine hydrochloride solution in ethanol as a solvent, taking 50-60 minutes and yielding 70-75%. Using ultrasonic irradiation, the same oximes were synthesized without solvent in 10-20 minutes, yielding 75-85%, which is higher than the traditional method. Yields were lowest for benzophenone oxime due to electron donation by phenyl groups decreasing carbonyl reactivity. Yields were highest for 4-chlorobenzaldehyde oxime due to electron withdrawal increasing reactivity. Thin layer chromatography confirmed the oximes produced
This document summarizes a study that investigated the removal of nitrate from groundwater using activated carbon prepared from rice husk and sludge from a paper industry wastewater treatment plant. The key findings are:
- Activated carbon from rice husk achieved a maximum nitrate removal of 93.5 mg/g at pH 4 and 4 hours of contact time. Activated carbon from paper industry sludge achieved 79.5 mg/g removal under the same conditions.
- Adsorption was best fitted by the Langmuir isotherm model and followed pseudo-second order kinetics.
- Increasing the ratio of ZnCl2 used for activation improved adsorption capacity, with a 1:
The document summarizes a study on using a combined anaerobic-aerobic reactor system to treat textile wastewater. Key findings include:
- Over 84.62% of ammonia nitrogen and about 98.9% of volatile suspended solids were removed by the system.
- Dissolved oxygen, pH, and organic changes were investigated during the nitrification and denitrification processes. Dissolved oxygen and pH were found to have only slight influences on nitrification, and a 10% removal of nitrogen resulted in about a 3% change in pH.
- The system was able to effectively remove nitrogen and organic materials from textile wastewater through the coupled anaerobic and aer
The document proposes using ultrasound as an advanced oxidation process to break down humic acid molecules in wastewater. Humic acid is a constituent of natural organic matter (NOM) that can clog activated carbon pores during filtration. The presentation would discuss NOM sources and health concerns, problems with NOM removal, how ultrasound works to break down molecules, previous research on using ultrasound to reactivate activated carbon, and the proposal to test ultrasound on humic acid before and after passing through an activated carbon bed. Future work would explore scaling up ultrasound and measuring humic acid concentrations more accurately.
Kinetic model for the sorption of cu (ii) and zn (ii) using lady fernAlexander Decker
This document summarizes a study on the kinetic modeling of copper and zinc ion sorption using lady fern leaf waste biomass. The study found that the rate of copper and zinc sorption was rapid within the initial 5-20 minutes, reaching a maximum in 30 minutes. Kinetic modeling showed the process followed a pseudo-second order model. Equilibrium sorption was examined using Langmuir and Freundlich isotherms, with the Langmuir model revealing a monolayer sorption capacity of 0.09mg/g for both copper and zinc ions. The results indicate lady fern leaf waste could effectively remove toxic metals from industrial effluents.
This document summarizes a study that used response surface methodology to optimize the removal of Zn2+ ions from aqueous solution using a novel biochar-alginate composite adsorbent. The researchers developed a quadratic model to predict Zn2+ removal based on initial Zn2+ concentration, adsorbent dose, and temperature. Their analysis found that initial Zn2+ concentration and adsorbent dose had the largest effect on removal efficiency. The optimum conditions for maximum 85% removal were determined to be an initial Zn2+ concentration of 43.18 mg/L, adsorbent dose of 0.062 g, and temperature of 313.5 K.
Existing biological nitrogen removal processes and current scope of advancementSandip Magdum
In India, to achieve the stringent norms of total nitrogen less than 10 mg/l in sewage treatment plant is a big challenge for the public - private facilities and organizations. After successful implementation of this norm the pollutant burden from rivers and natural water bodies certainly reduces. The use of conventional biological nitrogen removal (BNR) processes for new treatment facility development or retrofitting is also an energy and cost intensive practice. The process technologies offered by current market such as MLE, MBBR, IFAS and SBR are still in with downside of higher footprint, multi tank reactors, heavy instrumentation for IR and RAS which ultimately incur higher capital and operating cost. The current market need and lack of sustainable nitrogen removal applications, trigger to review the of all available efficient biological nitrogen removal processes. This review will gives an overall scenario of past and current biological nitrogen removal process technologies with showing possible scope and way forward towards more energy neutral nitrogen removal technologies.
11.distribution of polychlorinated biphenyls in surface waters of various sou...Alexander Decker
This document summarizes the results of a study measuring polychlorinated biphenyls (PCBs) in surface waters from various sources in the National Capital Region of Delhi, India. The total PCB concentrations ranged from 14-1768 ng/L with an average of 332 ng/L. Dioxin-like PCBs ranged from <1-146 ng/L accounting for 12% of total PCBs. The toxicity equivalent was also calculated. In terms of homolog distribution, tri-PCBs (47%) and tetra-PCBs (65%) dominated. Some locations had PCB levels higher than guidelines. Further study of PCB bioavailability and accumulation in aquatic biota is proposed to assess risks to ecosystems
Distribution of polychlorinated biphenyls in surface waters of various source...Alexander Decker
1. The study measured concentrations of 28 polychlorinated biphenyls (PCBs) including 12 dioxin-like PCBs in surface water samples from rivers, canals, lakes, ponds and drains in the National Capital Region of Delhi, India.
2. Total PCB concentrations ranged from 14-1768 ng/L with a mean of 332±42 ng/L. Dioxin-like PCBs ranged from <1-146 ng/L with a mean of 40±4 ng/L, accounting for 12% of total PCBs.
3. The most abundant PCB homologs were tetra-PCBs at 65% followed by tri-PCBs
The document discusses advanced oxidation processes (AOPs) which use hydroxyl radicals to oxidize organic compounds that cannot be degraded through biological or conventional water treatment processes. It describes various AOP technologies that generate hydroxyl radicals including ozone/UV, hydrogen peroxide/UV, Fenton reactions, photocatalysis, and ultrasound-assisted processes. Factors that influence AOP performance such as pH, presence of carbonates or natural organic matter are also summarized.
Industrial Waste Water Treatment Using An Attached MediaIRJET Journal
This document summarizes a study that evaluated the use of coconut coir as an attached growth media for treating industrial wastewater. The study investigated the effect of organic loading rate (OLR) and hydraulic retention time (HRT) on the removal of chemical oxygen demand (COD) in a reactor system using coir media. It found that COD removal efficiency increased with OLR up to 1.33 kg COD/m3d, above which removal efficiency decreased. The maximum COD removal of 89.9% was achieved at an OLR of 1.33 kg COD/m3d and HRT of 36 hours.
IRJET- A Review On Reduction of Phosphate from Industrial Cum Municipal Waste...IRJET Journal
This document reviews technologies for reducing phosphate from industrial and municipal wastewater using Moving Bed Biofilm Reactor (MBBR) technology. It discusses various methods for phosphate removal including physical, chemical, and biological treatments. Specifically, it provides details on MBBR technology, which combines activated sludge and trickling filter processes by using biomass in both suspended flocs and biofilm attached to carriers. The document concludes that MBBR is an effective biological treatment approach for phosphate removal as it can operate at high organic loads and is less sensitive to hydraulic overloading compared to other biological treatment methods.
IRJET- Design of Leachate Bioreactor for Dilkap CollegeIRJET Journal
This document describes a study conducted to design a leachate bioreactor for Dilkap College in Maharashtra, India. Specifically:
- Researchers created a model tank containing layered gravel, soil, food waste from the college canteen, and additional soil to treat leachate generated from the waste.
- The leachate collected from the model would be used in an anaerobic bioreactor to convert it into methane gas, which could then be used as an energy source.
- The document reviews several other studies on leachate treatment methods, such as using solar photocatalysis and membrane bioreactor technologies to reduce leachate pollution and convert it into usable fuels.
Treatment of Effluent from Granite Cutting Plant by Using Natural Adsorbents ...IJERD Editor
Granite cutting plant is one such industry that releases polluting and turbid effluent. The residue from all these processes is discharged with water as an effluent. The effluent mainly contains many solids that harm the environment. Hence it requires treatment techniques before disposal. Several conventional methods are available for removal of contaminants like coagulation, adsorption, polyelectrolyte methods and biological methods. Most of them are cost prohibitive. The reduction of solids concentration in the effluent before disposal by using the techniques, coagulation followed by adsorption using natural adsorbents, like rice husk carbon and saw dust carbon, in contrast to the usage of activated carbon as it is costly. From a local Granite cutting plant near Anantapur, the effluent is collected and its physico-chemical characteristics are estimated and found to be pH(7.5), TS(4240mg/l), TSS(21560mg/l), TDS(12373mg/l).Effluent obtained is subjected to coagulation by potash alum followed by adsorption using saw dust carbon and rice husk carbon.
This document summarizes a study that investigated the photocatalytic decolorization of methyl orange dye using TiO2/Fe3O4 and TiO2/Fe2O3 nanocomposites. Various ratios of the nanocomposites were synthesized using an ultrasonic-assisted deposition-precipitation method. Testing showed the 1 wt% Fe3O4/TiO2 nanocomposite achieved about 40% decolorization of methyl orange within 60 minutes of UV irradiation at room temperature, though it exhibited the least magnetism. Characterization of the nanocomposites involved scanning electron microscopy, X-ray diffraction, Brunauer–Emmet–Teller surface area analysis, and band gap determination.
Metodos anticonceptivos y planificación familiarSandra Liliana
El documento describe los diferentes métodos anticonceptivos y la importancia de la planificación familiar. Explica que todas las personas tienen derecho a decidir cuándo y cuántos hijos tener. Luego detalla los principales tipos de métodos anticonceptivos, incluyendo métodos naturales, de barrera, hormonales y definitivos o quirúrgicos. El objetivo es informar sobre las opciones disponibles para prevenir embarazos no deseados y ejercer el derecho a la planificación familiar.
Industrial wastewater treatment via photocatalysisJay Lakhani
This document discusses using photocatalysis for industrial wastewater treatment. Specifically, it examines using ZnO nanoparticles as a photocatalyst coated on a support material. An experimental setup involved circulating 1.5 liters of textile wastewater through a ZnO coated reactor for 4 hours under solar radiation. Various parameters that affect the wastewater treatment were studied, including temperature, dye concentration, reaction time, pH and TOC variation over time. Results showed ZnO was more effective than TiO2 at degrading pollutants like COD. However, issues with ZnO include photocorrosion and difficulty recovering the nanoparticles from water. Overall, photocatalysis shows potential as a green technology for treating industrial wastewater
Development of an experimental rig for bioremediation studiesAlexander Decker
The document describes the development of an experimental rig for bioremediation studies using indigenous technology. Key details include:
- The rig consists of various units like air pretreatment, fixed bed bioreactors, volatile organic compound traps, air flow meter, and carbon dioxide traps.
- Components were sized, designed, and fabricated locally at low cost. Testing showed the rig effectively degraded 75% of oil and grease from contaminated soil over 10 weeks.
- The rig was used to study bioremediation of soil contaminated with spent motor oil in 6 treatments with various additives over room temperature.
The document summarizes advanced oxidation processes (AOPs) for treating food industry wastewater. It discusses four main AOP groups - electrochemical oxidation, Fenton's process, ozonation, and photocatalytic processes. All generate highly reactive hydroxyl radicals to degrade organic pollutants that are resistant to biological treatment. Electrochemical oxidation uses electrodes to produce hydroxyl radicals and has effectively treated various food industry wastewaters. Fenton's process uses ferrous ions and hydrogen peroxide to catalytically produce hydroxyl radicals. Photocatalytic processes employ materials like TiO2 and UV light to generate radicals.
This document compares the synthesis of oximes using traditional chemical methods versus ultrasonic irradiation. Oximes are important organic intermediates. The traditional method involves refluxing carbonyl compounds with hydroxylamine hydrochloride solution in ethanol as a solvent, taking 50-60 minutes and yielding 70-75%. Using ultrasonic irradiation, the same oximes were synthesized without solvent in 10-20 minutes, yielding 75-85%, which is higher than the traditional method. Yields were lowest for benzophenone oxime due to electron donation by phenyl groups decreasing carbonyl reactivity. Yields were highest for 4-chlorobenzaldehyde oxime due to electron withdrawal increasing reactivity. Thin layer chromatography confirmed the oximes produced
This document summarizes a study that investigated the removal of nitrate from groundwater using activated carbon prepared from rice husk and sludge from a paper industry wastewater treatment plant. The key findings are:
- Activated carbon from rice husk achieved a maximum nitrate removal of 93.5 mg/g at pH 4 and 4 hours of contact time. Activated carbon from paper industry sludge achieved 79.5 mg/g removal under the same conditions.
- Adsorption was best fitted by the Langmuir isotherm model and followed pseudo-second order kinetics.
- Increasing the ratio of ZnCl2 used for activation improved adsorption capacity, with a 1:
The document summarizes a study on using a combined anaerobic-aerobic reactor system to treat textile wastewater. Key findings include:
- Over 84.62% of ammonia nitrogen and about 98.9% of volatile suspended solids were removed by the system.
- Dissolved oxygen, pH, and organic changes were investigated during the nitrification and denitrification processes. Dissolved oxygen and pH were found to have only slight influences on nitrification, and a 10% removal of nitrogen resulted in about a 3% change in pH.
- The system was able to effectively remove nitrogen and organic materials from textile wastewater through the coupled anaerobic and aer
The document proposes using ultrasound as an advanced oxidation process to break down humic acid molecules in wastewater. Humic acid is a constituent of natural organic matter (NOM) that can clog activated carbon pores during filtration. The presentation would discuss NOM sources and health concerns, problems with NOM removal, how ultrasound works to break down molecules, previous research on using ultrasound to reactivate activated carbon, and the proposal to test ultrasound on humic acid before and after passing through an activated carbon bed. Future work would explore scaling up ultrasound and measuring humic acid concentrations more accurately.
Kinetic model for the sorption of cu (ii) and zn (ii) using lady fernAlexander Decker
This document summarizes a study on the kinetic modeling of copper and zinc ion sorption using lady fern leaf waste biomass. The study found that the rate of copper and zinc sorption was rapid within the initial 5-20 minutes, reaching a maximum in 30 minutes. Kinetic modeling showed the process followed a pseudo-second order model. Equilibrium sorption was examined using Langmuir and Freundlich isotherms, with the Langmuir model revealing a monolayer sorption capacity of 0.09mg/g for both copper and zinc ions. The results indicate lady fern leaf waste could effectively remove toxic metals from industrial effluents.
This document summarizes a study that used response surface methodology to optimize the removal of Zn2+ ions from aqueous solution using a novel biochar-alginate composite adsorbent. The researchers developed a quadratic model to predict Zn2+ removal based on initial Zn2+ concentration, adsorbent dose, and temperature. Their analysis found that initial Zn2+ concentration and adsorbent dose had the largest effect on removal efficiency. The optimum conditions for maximum 85% removal were determined to be an initial Zn2+ concentration of 43.18 mg/L, adsorbent dose of 0.062 g, and temperature of 313.5 K.
Existing biological nitrogen removal processes and current scope of advancementSandip Magdum
In India, to achieve the stringent norms of total nitrogen less than 10 mg/l in sewage treatment plant is a big challenge for the public - private facilities and organizations. After successful implementation of this norm the pollutant burden from rivers and natural water bodies certainly reduces. The use of conventional biological nitrogen removal (BNR) processes for new treatment facility development or retrofitting is also an energy and cost intensive practice. The process technologies offered by current market such as MLE, MBBR, IFAS and SBR are still in with downside of higher footprint, multi tank reactors, heavy instrumentation for IR and RAS which ultimately incur higher capital and operating cost. The current market need and lack of sustainable nitrogen removal applications, trigger to review the of all available efficient biological nitrogen removal processes. This review will gives an overall scenario of past and current biological nitrogen removal process technologies with showing possible scope and way forward towards more energy neutral nitrogen removal technologies.
11.distribution of polychlorinated biphenyls in surface waters of various sou...Alexander Decker
This document summarizes the results of a study measuring polychlorinated biphenyls (PCBs) in surface waters from various sources in the National Capital Region of Delhi, India. The total PCB concentrations ranged from 14-1768 ng/L with an average of 332 ng/L. Dioxin-like PCBs ranged from <1-146 ng/L accounting for 12% of total PCBs. The toxicity equivalent was also calculated. In terms of homolog distribution, tri-PCBs (47%) and tetra-PCBs (65%) dominated. Some locations had PCB levels higher than guidelines. Further study of PCB bioavailability and accumulation in aquatic biota is proposed to assess risks to ecosystems
Distribution of polychlorinated biphenyls in surface waters of various source...Alexander Decker
1. The study measured concentrations of 28 polychlorinated biphenyls (PCBs) including 12 dioxin-like PCBs in surface water samples from rivers, canals, lakes, ponds and drains in the National Capital Region of Delhi, India.
2. Total PCB concentrations ranged from 14-1768 ng/L with a mean of 332±42 ng/L. Dioxin-like PCBs ranged from <1-146 ng/L with a mean of 40±4 ng/L, accounting for 12% of total PCBs.
3. The most abundant PCB homologs were tetra-PCBs at 65% followed by tri-PCBs
The document discusses advanced oxidation processes (AOPs) which use hydroxyl radicals to oxidize organic compounds that cannot be degraded through biological or conventional water treatment processes. It describes various AOP technologies that generate hydroxyl radicals including ozone/UV, hydrogen peroxide/UV, Fenton reactions, photocatalysis, and ultrasound-assisted processes. Factors that influence AOP performance such as pH, presence of carbonates or natural organic matter are also summarized.
Industrial Waste Water Treatment Using An Attached MediaIRJET Journal
This document summarizes a study that evaluated the use of coconut coir as an attached growth media for treating industrial wastewater. The study investigated the effect of organic loading rate (OLR) and hydraulic retention time (HRT) on the removal of chemical oxygen demand (COD) in a reactor system using coir media. It found that COD removal efficiency increased with OLR up to 1.33 kg COD/m3d, above which removal efficiency decreased. The maximum COD removal of 89.9% was achieved at an OLR of 1.33 kg COD/m3d and HRT of 36 hours.
IRJET- A Review On Reduction of Phosphate from Industrial Cum Municipal Waste...IRJET Journal
This document reviews technologies for reducing phosphate from industrial and municipal wastewater using Moving Bed Biofilm Reactor (MBBR) technology. It discusses various methods for phosphate removal including physical, chemical, and biological treatments. Specifically, it provides details on MBBR technology, which combines activated sludge and trickling filter processes by using biomass in both suspended flocs and biofilm attached to carriers. The document concludes that MBBR is an effective biological treatment approach for phosphate removal as it can operate at high organic loads and is less sensitive to hydraulic overloading compared to other biological treatment methods.
IRJET- Design of Leachate Bioreactor for Dilkap CollegeIRJET Journal
This document describes a study conducted to design a leachate bioreactor for Dilkap College in Maharashtra, India. Specifically:
- Researchers created a model tank containing layered gravel, soil, food waste from the college canteen, and additional soil to treat leachate generated from the waste.
- The leachate collected from the model would be used in an anaerobic bioreactor to convert it into methane gas, which could then be used as an energy source.
- The document reviews several other studies on leachate treatment methods, such as using solar photocatalysis and membrane bioreactor technologies to reduce leachate pollution and convert it into usable fuels.
Treatment of Effluent from Granite Cutting Plant by Using Natural Adsorbents ...IJERD Editor
Granite cutting plant is one such industry that releases polluting and turbid effluent. The residue from all these processes is discharged with water as an effluent. The effluent mainly contains many solids that harm the environment. Hence it requires treatment techniques before disposal. Several conventional methods are available for removal of contaminants like coagulation, adsorption, polyelectrolyte methods and biological methods. Most of them are cost prohibitive. The reduction of solids concentration in the effluent before disposal by using the techniques, coagulation followed by adsorption using natural adsorbents, like rice husk carbon and saw dust carbon, in contrast to the usage of activated carbon as it is costly. From a local Granite cutting plant near Anantapur, the effluent is collected and its physico-chemical characteristics are estimated and found to be pH(7.5), TS(4240mg/l), TSS(21560mg/l), TDS(12373mg/l).Effluent obtained is subjected to coagulation by potash alum followed by adsorption using saw dust carbon and rice husk carbon.
This document summarizes a study that investigated the photocatalytic decolorization of methyl orange dye using TiO2/Fe3O4 and TiO2/Fe2O3 nanocomposites. Various ratios of the nanocomposites were synthesized using an ultrasonic-assisted deposition-precipitation method. Testing showed the 1 wt% Fe3O4/TiO2 nanocomposite achieved about 40% decolorization of methyl orange within 60 minutes of UV irradiation at room temperature, though it exhibited the least magnetism. Characterization of the nanocomposites involved scanning electron microscopy, X-ray diffraction, Brunauer–Emmet–Teller surface area analysis, and band gap determination.
Metodos anticonceptivos y planificación familiarSandra Liliana
El documento describe los diferentes métodos anticonceptivos y la importancia de la planificación familiar. Explica que todas las personas tienen derecho a decidir cuándo y cuántos hijos tener. Luego detalla los principales tipos de métodos anticonceptivos, incluyendo métodos naturales, de barrera, hormonales y definitivos o quirúrgicos. El objetivo es informar sobre las opciones disponibles para prevenir embarazos no deseados y ejercer el derecho a la planificación familiar.
El documento describe el catéter arterial pulmonar (CAP), también conocido como catéter Swan Ganz, el cual se inserta en la arteria pulmonar para monitorear el funcionamiento cardíaco y diagnosticar enfermedades. El catéter Swan Ganz es flexible y flotante e ingresa al corazón a través de las cámaras hasta la arteria pulmonar para medir presiones, gasto cardíaco y resistencia vascular. El catéter se utiliza para cirugía no cardíaca y cardíaca, y permite medir presiones directa e indirectamente para
Existen diversos métodos anticonceptivos como el dispositivo intrauterino, preservativos, píldora anticonceptiva, anillo vaginal e inyecciones hormonales. La elección del método depende de factores como la salud, frecuencia de relaciones sexuales, efectos secundarios y facilidad de uso. Los métodos se clasifican según su efectividad, desde opciones como la vasectomía y el DIU, hasta métodos como el coito interrumpido. Algunos métodos comunes incluyen el anillo vaginal mensual, la pí
Este documento describe diferentes métodos anticonceptivos, incluyendo métodos naturales, de barrera, químicos y hormonales, quirúrgicos y de emergencia. Explica cómo funcionan cada uno y su eficacia relativa para prevenir embarazos no deseados. Los métodos más efectivos incluyen dispositivos intrauterinos, anticoncepción hormonal como parches y píldoras, anillos vaginales y esterilización quirúrgica; mientras que los menos efectivos son métodos naturales y de retiro. También enfat
Este documento describe diferentes métodos anticonceptivos naturales y artificiales. Entre los métodos naturales se encuentran la abstinencia, el método del calendario, el control de la temperatura basal y la lactancia. Los métodos artificiales incluyen barreras como condones y diafragmas, métodos quirúrgicos como la vasectomía y la ligadura de trompas, métodos hormonales como las píldoras y parches, y métodos de emergencia. Finalmente, se proporciona un cuadro comparativo sobre la efectividad de los diferentes métodos para
Este documento describe varios métodos anticonceptivos convencionales como preservativos masculinos y femeninos, diafragmas y dispositivos intrauterinos. También describe métodos químicos y hormonales como la píldora anticonceptiva, inyecciones hormonales, implantes hormonales y espermicidas. Finalmente, menciona métodos quirúrgicos como la vasectomía y la ligadura de trompas, e identifica algunos métodos como inútiles para la anticoncepción.
Este documento describe los diferentes métodos anticonceptivos, incluyendo métodos naturales como el calendario del ritmo y el método de Billings, métodos de barrera como condones y diafragmas, y métodos hormonales como pastillas anticonceptivas, implantes subdérmicos e inyecciones. Explica brevemente qué son cada uno de estos métodos y su función de prevenir embarazos no deseados.
Applicability of Fenton Process for Treatment of Industrial Effluents: A ReviewIJERA Editor
Wastewater and effluent treatment has undergone innovative changes over the years. Traditional wastewater treatment has yielded to modern and path-breaking procedures which are more efficient and effective. The world of difficulties and unknown has opened new avenues and paths to highly feasible effluent treatment procedures, so the vigorous importance of advanced oxidation procedures. This review paper will delineate the increasing importance of various advanced oxidation processes including Fenton treatment for wastewater. Advanced oxidation processes (AOP’s), which involve and includes the in-situ generation of highly potent chemical oxidants such as the hydroxyl radical, have emerged as an important avenue of technologies to accelerate the non-selective oxidation and thus the destruction of a wide range of non-degradable organic contaminants in wastewater which cannot be eliminated biologically. Advanced oxidation processes (AOP) are technologies based on the generation of highly reactive species, the hydroxyl radicals, used in oxidative degradation procedures for organic compounds dissolved or dispersed in aquatic media. These processes are promising alternatives for decontamination of media containing dissolved recalcitrant organic substances, which would not be efficiently removed by conventional methods.
Sonophotocatalytic Degradation of Waste WaterTejas Deshpande
The document presents a technical paper on recent trends in chemical engineering, specifically sonophotocatalytic degradation of wastewater. It discusses various sources and types of wastewater as well as current treatment methods and their drawbacks. Advanced oxidation processes (AOPs) like sonophotocatalysis are introduced as promising alternatives. Sonophotocatalysis combines sonication and photocatalysis to generate more hydroxyl radicals for degradation. A case study demonstrates over 95% degradation of pharmaceutical wastewater pollutants using this technique. While sonophotocatalysis has benefits, further research is still needed to optimize costs and fully understand degradation mechanisms for wide application.
Nanotechnology can be used to clean the air through various applications. Some key points:
1. Nanoparticles like titanium dioxide can be used in photocatalytic filters to break down air pollutants like VOCs, NOx, and pathogens into harmless byproducts like water and carbon dioxide when exposed to light.
2. Other nanomaterials like gold-embedded manganese oxide have been shown to effectively remove common indoor air pollutants like acetaldehyde, toluene, and hexane at room temperature.
3. Nanotechnology allows more effective air filtration and purification systems to be developed for indoor and outdoor applications to improve air quality.
A short description of thermal technologies for the recovery of ammonia from N-rich wastewaters and expirementing with membrane distillation for getting better results.
Degradation of Paracetamol by Electro-Fenton and Photoelectro-Fenton Processe...Oswar Mungkasa
prepared by M.C. Lu *, M.L.Veciana**, M.D.G. de Luna*** * Department of Environmental Resources Management, Chia Nan University of Pharmacy and Science, Tainan 717, Taiwan **Environmental Engineering Graduate Program, University of the Philippines, 1011 Diliman, Quezon City, Philippines *** Department of Chemical Engineering, University of the Philippines, 1011 Diliman, Quezon City, Phi for Urban Environments in Asia, 25-28 May 2011, Manila, Philippines. organized by International Water Association (IWA).
This document discusses spinel ferrite magnetic nanoparticles as an alternative for wastewater treatment. It begins with an introduction explaining the global challenges of water pollution and scarcity. It then provides details on conventional wastewater treatment methods and their limitations. The document introduces nanotechnology as a promising new approach, specifically highlighting photocatalysis, nanofiltration, and nanoadsorbents using magnetic nanoparticles. It focuses on the properties of spinel ferrite nanoparticles that make them well-suited for wastewater remediation applications like adsorption and magnetic separation.
Lagoas de alta taxa versando sobre avanços e princiais beneficios da tecnologiaLucasVassalledeCastr
This document summarizes a research project on using high rate algal ponds (HRAP) for post-treating sewage effluent from upflow anaerobic sludge blanket (UASB) reactors. UASB reactors are commonly used for sewage treatment in Brazil and other Latin American countries due to their lower costs compared to other technologies. However, UASB effluent does not always meet discharge standards for biochemical oxygen demand, nutrients, and pathogens. The research aims to evaluate whether HRAP can provide tertiary treatment of UASB effluent through anaerobic co-digestion of algal biomass, and further removal of nutrients and micropollutants, while improving sustainability.
Industrial Water Treatment Optimization at Kelly Air Force Basenjcnews777
The document discusses an optimization study conducted on an innovative co-precipitation process for removing heavy metals from industrial wastewater. The study tested the effects of variables like influent quality, flow rate, chemical dosages, and solids loading on the process's effectiveness. It found that the process was highly effective across a wide range of conditions, removing over 90% of metals in many tests. The optimal conditions were determined to be an iron dosage of 10-25 mg/L, an iron to polymer ratio of 1:1, and a solids loading of 50% in the reactor.
Sonophotocatalysis is an advanced water treatment technique that combines sonocatalysis (using ultrasound) and photocatalysis (using light) for enhanced degradation of water pollutants. It generates reactive oxygen species (ROS) through three mechanisms - sonoluminescence during cavitation, excitation of the photocatalyst by ultrasound-generated light, and increased ROS production when the photocatalyst is exposed to both light and ultrasound. This synergistic combination allows for more efficient mineralization of a wide range of organic and inorganic pollutants into harmless byproducts like CO2 and H2O. The review analyzes advances in using sonophotocatalysis to disinfect microbes and treat various wastew
This document summarizes a study on the membrane assisted electrochemical degradation of three textile dyes: Quinoline Yellow, Eosin B, and Rose Bengal. The study characterized the dyes and evaluated their degradation using four different polyelectrolyte membranes in an electrochemical membrane reactor. Degradation was compared for the different membranes and optimized experimental conditions. The goal was to develop an electrochemical membrane process for treating and reusing textile dye wastewater.
This document summarizes a study that investigated the use of Parthenium stem powder for biosorption of lead from aqueous solutions. The study optimized various process parameters like pH, contact time, temperature, adsorbent dosage and initial lead concentration using response surface methodology. Batch experiments using Box-Behnken design showed that the optimum conditions for maximum lead biosorption were a pH of 5, initial lead concentration of 20 mg/L, and adsorbent dosage of 30 g/L. Kinetic, thermodynamic and isotherm studies demonstrated that the adsorption process was spontaneous and fit the pseudo-second order kinetic model and Langmuir isotherm model. The Parthenium stem powder was found to
This document summarizes a study that investigated the use of Parthenium stem powder for biosorption of lead from aqueous solutions. The study optimized various process parameters like pH, contact time, temperature, adsorbent dosage and initial lead concentration using response surface methodology. Batch experiments using Box-Behnken design showed that the optimum conditions for maximum lead biosorption were a pH of 5, initial lead concentration of 20 mg/L, and adsorbent dosage of 30 g/L. Kinetic, thermodynamic, and isotherm studies demonstrated that the adsorption process was spontaneous and fit the pseudo-second order kinetic model and Langmuir isotherm model. The Parthenium stem powder was found
This document describes a study investigating the use of Parthenium stem powder for removing lead from aqueous solutions. Response surface methodology was used to optimize the conditions for lead biosorption based on variables like pH, initial lead concentration, and adsorbent dosage. Experiments were conducted using a Box-Behnken design. The results showed that Parthenium stem powder can reduce lead concentration by up to 72.74% at pH 5, 20 mg/L initial concentration, and 30 g/L adsorbent dosage. Kinetic, thermodynamic, and isotherm studies provided insights into the adsorption process.
This document is a thesis project examining innovative biological phosphate and anaerobic digestion technology for waste treatment, energy generation, and phosphorus recovery. It includes an abstract, introduction covering topics like sewage, current bioremediation methods, anaerobic digestion processes, low temperature anaerobic digestion, bioreactor configurations, and the global phosphorus crisis. It also outlines the materials and methods, expected results sections, and planned discussion. The introduction provides background on anaerobic digestion and examines its application to low-temperature wastewater treatment.
4. bello 2017. applications of fluidized bed reactor in wastewater treatmentBritani Keith
This document reviews the application of fluidized bed reactors in wastewater treatment, focusing on the major design and operational parameters. Fluidized bed reactors can be used for advanced oxidation processes, biological treatment, and adsorption processes for wastewater containing recalcitrant pollutants. Both liquid-solid and gas-liquid-solid fluidized bed reactors are discussed. Important parameters reviewed include reactor geometry, support material characteristics, superficial fluid velocity, and other operational factors. The review concludes with perspectives on future research directions.
Bijay Thapa, Nawa Raj Khatiwada, Anish Ghimire and Bikash Adhikari . “Study of Pollutant Removal in Activated Sludge Process Using Lab Scale Plant by Intermittent Aeration” United International Journal for Research & Technology (UIJRT) 1.2 (2019): 01-07.
Experimental Studies on Bioregeneration of Activated Carbon Contaminated With...IOSR Journals
The document summarizes an experimental study on bioregenerating activated carbon contaminated with hydrocarbons. The researchers characterized virgin and regenerated activated carbon and found the regeneration process maintained the carbon's key properties. They conducted experiments regenerating contaminated carbon using different volumes of Pseudomonas Putida bacteria and temperatures. Increasing bacteria volume and temperature both increased regeneration rates by reducing total hydrocarbon content more quickly. The optimal conditions were 30-40ml of bacteria at 35-40°C, providing effective regeneration while remaining economical.
REMOVAL OF POLLUTANTS USING RADIAL AND VERTICAL FLOW REGIME REACTORSIAEME Publication
Batch and continuous processes were conducted to study the adsorption of methylene blue dye on to three adsorbent materials, commercial activated carbon, chemically activated corncob carbon with phosphoric acid and ion exchange resin (akualite). Batch processes were established to show the effects of solution pH, contact time, adsorbent dosage, agitation speed and initial dye concentration. Two isotherm models, Freundlich and Langmuir fitted with the experimental data found from batch processes, the Langmuir model fitted well than the Freundlich, with maximum adsorption capacities of 16.21, 30.95 and 77.52 mg/g and R2 of 0.952, 0.992 and 0.995 predicted by commercial activated carbon, corncob activated carbon akualite respectively.
This document reviews the use of nanotechnology for waste water treatment. It discusses how nanoparticles have a high surface area and unique properties that allow them to efficiently remove toxins, microbes, and other contaminants from water. Various nanomaterials can be used, including metal nanoparticles, carbon nanomaterials, zeolites, and dendrimers. The document summarizes recent research on nanostructured catalytic membranes, nanosorbents, nanocatalysts, bioactive nanoparticles, biomimetic membranes, and molecularly imprinted polymers for applications in water treatment. Nanotechnology approaches provide efficient, precise, and scalable ways to treat waste water with benefits like lower costs and energy usage compared to conventional methods. However, more research is
This research article summarizes a study that tested a new wastewater treatment technology called a fluidized immobilized carbon catalytic oxidation (FICCO) reactor. The FICCO reactor uses activated carbon produced from rice husks as a catalyst to remove organic contaminants like COD and BOD from domestic wastewater. Six FICCO reactor models were constructed with triangular sheets at the top to improve catalyst retention. Testing found the optimum catalyst dosage was 12g of rice husk-activated carbon per 620ml of wastewater, achieving 75.6-92.4% COD removal and 74.9-89.5% BOD removal. The FICCO reactor effectively treated organic pollutants and
Similar to A review of imperative technologies for for waste water tratament 1 (20)
“An Outlook of the Ongoing and Future Relationship between Blockchain Technologies and Process-aware Information Systems.” Invited talk at the joint workshop on Blockchain for Information Systems (BC4IS) and Blockchain for Trusted Data Sharing (B4TDS), co-located with with the 36th International Conference on Advanced Information Systems Engineering (CAiSE), 3 June 2024, Limassol, Cyprus.
For the full video of this presentation, please visit: https://www.edge-ai-vision.com/2024/06/building-and-scaling-ai-applications-with-the-nx-ai-manager-a-presentation-from-network-optix/
Robin van Emden, Senior Director of Data Science at Network Optix, presents the “Building and Scaling AI Applications with the Nx AI Manager,” tutorial at the May 2024 Embedded Vision Summit.
In this presentation, van Emden covers the basics of scaling edge AI solutions using the Nx tool kit. He emphasizes the process of developing AI models and deploying them globally. He also showcases the conversion of AI models and the creation of effective edge AI pipelines, with a focus on pre-processing, model conversion, selecting the appropriate inference engine for the target hardware and post-processing.
van Emden shows how Nx can simplify the developer’s life and facilitate a rapid transition from concept to production-ready applications.He provides valuable insights into developing scalable and efficient edge AI solutions, with a strong focus on practical implementation.
Let's Integrate MuleSoft RPA, COMPOSER, APM with AWS IDP along with Slackshyamraj55
Discover the seamless integration of RPA (Robotic Process Automation), COMPOSER, and APM with AWS IDP enhanced with Slack notifications. Explore how these technologies converge to streamline workflows, optimize performance, and ensure secure access, all while leveraging the power of AWS IDP and real-time communication via Slack notifications.
Driving Business Innovation: Latest Generative AI Advancements & Success StorySafe Software
Are you ready to revolutionize how you handle data? Join us for a webinar where we’ll bring you up to speed with the latest advancements in Generative AI technology and discover how leveraging FME with tools from giants like Google Gemini, Amazon, and Microsoft OpenAI can supercharge your workflow efficiency.
During the hour, we’ll take you through:
Guest Speaker Segment with Hannah Barrington: Dive into the world of dynamic real estate marketing with Hannah, the Marketing Manager at Workspace Group. Hear firsthand how their team generates engaging descriptions for thousands of office units by integrating diverse data sources—from PDF floorplans to web pages—using FME transformers, like OpenAIVisionConnector and AnthropicVisionConnector. This use case will show you how GenAI can streamline content creation for marketing across the board.
Ollama Use Case: Learn how Scenario Specialist Dmitri Bagh has utilized Ollama within FME to input data, create custom models, and enhance security protocols. This segment will include demos to illustrate the full capabilities of FME in AI-driven processes.
Custom AI Models: Discover how to leverage FME to build personalized AI models using your data. Whether it’s populating a model with local data for added security or integrating public AI tools, find out how FME facilitates a versatile and secure approach to AI.
We’ll wrap up with a live Q&A session where you can engage with our experts on your specific use cases, and learn more about optimizing your data workflows with AI.
This webinar is ideal for professionals seeking to harness the power of AI within their data management systems while ensuring high levels of customization and security. Whether you're a novice or an expert, gain actionable insights and strategies to elevate your data processes. Join us to see how FME and AI can revolutionize how you work with data!
TrustArc Webinar - 2024 Global Privacy SurveyTrustArc
How does your privacy program stack up against your peers? What challenges are privacy teams tackling and prioritizing in 2024?
In the fifth annual Global Privacy Benchmarks Survey, we asked over 1,800 global privacy professionals and business executives to share their perspectives on the current state of privacy inside and outside of their organizations. This year’s report focused on emerging areas of importance for privacy and compliance professionals, including considerations and implications of Artificial Intelligence (AI) technologies, building brand trust, and different approaches for achieving higher privacy competence scores.
See how organizational priorities and strategic approaches to data security and privacy are evolving around the globe.
This webinar will review:
- The top 10 privacy insights from the fifth annual Global Privacy Benchmarks Survey
- The top challenges for privacy leaders, practitioners, and organizations in 2024
- Key themes to consider in developing and maintaining your privacy program
GraphSummit Singapore | The Art of the Possible with Graph - Q2 2024Neo4j
Neha Bajwa, Vice President of Product Marketing, Neo4j
Join us as we explore breakthrough innovations enabled by interconnected data and AI. Discover firsthand how organizations use relationships in data to uncover contextual insights and solve our most pressing challenges – from optimizing supply chains, detecting fraud, and improving customer experiences to accelerating drug discoveries.
Building Production Ready Search Pipelines with Spark and MilvusZilliz
Spark is the widely used ETL tool for processing, indexing and ingesting data to serving stack for search. Milvus is the production-ready open-source vector database. In this talk we will show how to use Spark to process unstructured data to extract vector representations, and push the vectors to Milvus vector database for search serving.
Maruthi Prithivirajan, Head of ASEAN & IN Solution Architecture, Neo4j
Get an inside look at the latest Neo4j innovations that enable relationship-driven intelligence at scale. Learn more about the newest cloud integrations and product enhancements that make Neo4j an essential choice for developers building apps with interconnected data and generative AI.
Climate Impact of Software Testing at Nordic Testing DaysKari Kakkonen
My slides at Nordic Testing Days 6.6.2024
Climate impact / sustainability of software testing discussed on the talk. ICT and testing must carry their part of global responsibility to help with the climat warming. We can minimize the carbon footprint but we can also have a carbon handprint, a positive impact on the climate. Quality characteristics can be added with sustainability, and then measured continuously. Test environments can be used less, and in smaller scale and on demand. Test techniques can be used in optimizing or minimizing number of tests. Test automation can be used to speed up testing.
GraphRAG for Life Science to increase LLM accuracyTomaz Bratanic
GraphRAG for life science domain, where you retriever information from biomedical knowledge graphs using LLMs to increase the accuracy and performance of generated answers
HCL Notes und Domino Lizenzkostenreduzierung in der Welt von DLAUpanagenda
Webinar Recording: https://www.panagenda.com/webinars/hcl-notes-und-domino-lizenzkostenreduzierung-in-der-welt-von-dlau/
DLAU und die Lizenzen nach dem CCB- und CCX-Modell sind für viele in der HCL-Community seit letztem Jahr ein heißes Thema. Als Notes- oder Domino-Kunde haben Sie vielleicht mit unerwartet hohen Benutzerzahlen und Lizenzgebühren zu kämpfen. Sie fragen sich vielleicht, wie diese neue Art der Lizenzierung funktioniert und welchen Nutzen sie Ihnen bringt. Vor allem wollen Sie sicherlich Ihr Budget einhalten und Kosten sparen, wo immer möglich. Das verstehen wir und wir möchten Ihnen dabei helfen!
Wir erklären Ihnen, wie Sie häufige Konfigurationsprobleme lösen können, die dazu führen können, dass mehr Benutzer gezählt werden als nötig, und wie Sie überflüssige oder ungenutzte Konten identifizieren und entfernen können, um Geld zu sparen. Es gibt auch einige Ansätze, die zu unnötigen Ausgaben führen können, z. B. wenn ein Personendokument anstelle eines Mail-Ins für geteilte Mailboxen verwendet wird. Wir zeigen Ihnen solche Fälle und deren Lösungen. Und natürlich erklären wir Ihnen das neue Lizenzmodell.
Nehmen Sie an diesem Webinar teil, bei dem HCL-Ambassador Marc Thomas und Gastredner Franz Walder Ihnen diese neue Welt näherbringen. Es vermittelt Ihnen die Tools und das Know-how, um den Überblick zu bewahren. Sie werden in der Lage sein, Ihre Kosten durch eine optimierte Domino-Konfiguration zu reduzieren und auch in Zukunft gering zu halten.
Diese Themen werden behandelt
- Reduzierung der Lizenzkosten durch Auffinden und Beheben von Fehlkonfigurationen und überflüssigen Konten
- Wie funktionieren CCB- und CCX-Lizenzen wirklich?
- Verstehen des DLAU-Tools und wie man es am besten nutzt
- Tipps für häufige Problembereiche, wie z. B. Team-Postfächer, Funktions-/Testbenutzer usw.
- Praxisbeispiele und Best Practices zum sofortigen Umsetzen
Unlock the Future of Search with MongoDB Atlas_ Vector Search Unleashed.pdfMalak Abu Hammad
Discover how MongoDB Atlas and vector search technology can revolutionize your application's search capabilities. This comprehensive presentation covers:
* What is Vector Search?
* Importance and benefits of vector search
* Practical use cases across various industries
* Step-by-step implementation guide
* Live demos with code snippets
* Enhancing LLM capabilities with vector search
* Best practices and optimization strategies
Perfect for developers, AI enthusiasts, and tech leaders. Learn how to leverage MongoDB Atlas to deliver highly relevant, context-aware search results, transforming your data retrieval process. Stay ahead in tech innovation and maximize the potential of your applications.
#MongoDB #VectorSearch #AI #SemanticSearch #TechInnovation #DataScience #LLM #MachineLearning #SearchTechnology
Pushing the limits of ePRTC: 100ns holdover for 100 daysAdtran
At WSTS 2024, Alon Stern explored the topic of parametric holdover and explained how recent research findings can be implemented in real-world PNT networks to achieve 100 nanoseconds of accuracy for up to 100 days.
Pushing the limits of ePRTC: 100ns holdover for 100 days
A review of imperative technologies for for waste water tratament 1
1. Advances in Environmental Research 8 (2004) 501–551
A review of imperative technologies for wastewater treatment I:
oxidation technologies at ambient conditions
Parag R. Gogate*, Aniruddha B. Pandit
Chemical Engineering Section, M.U.I.C.T., Matunga, Mumbai 400019, India
Accepted 4 April 2003
Abstract
Nowadays, due to the increasing presence of molecules, refractory to the microorganisms in the wastewater streams,
the conventional biological methods cannot be used for complete treatment of the effluent and hence, introduction of
newer technologies to degrade these refractory molecules into smaller molecules, which can be further oxidized by
biological methods, has become imperative. The present work aims at highlighting five different oxidation processes
operating at ambient conditions viz. cavitation, photocatalytic oxidation, Fenton’s chemistry (belonging to the class
of advanced oxidation processes) and ozonation, use of hydrogen peroxide (belonging to the class of chemical
oxidation technologies). The work highlights the basics of these individual processes including the optimum operating
parameters and the reactor design aspects with a complete overview of the various applications to wastewater
treatment in the recent years. In the next article of this two article series on imperative technologies, hybrid methods
(basically combination of the oxidation processes) will be discussed and the current work forms a useful foundation
for the work focusing on hybrid technologies.
ᮊ 2003 Elsevier Ltd. All rights reserved.
Keywords: Wastewater treatment; Cavitation; Photocatalysis; Ozonation; Hydrogen peroxide; Fenton’s chemistry; Optimum
treatment conditions
1. Introduction stream to a certain minimum level in order to comply
with the environmental laws, which are becoming more
New developments in the variety of fields to meet stringent these days. Thus, research into new or more
the ever-increasing requirements of human beings have efficient waste water treatment technologies so as to
also led to the presence of new compounds in the degrade the complex refractory molecules into simpler
effluent streams of processing plants, which are not molecules is vital to combat the deteriorating water
readily degraded by the conventional effluent treatment quality. It should be noted that some of these newly
methods (Bauer and Fallmann, 1997; Mantzavinos et developed technologies, e.g. cavitation may be more
al., 1997; Otal et al. 1997; Feigelson et al., 2000). The efficient on the laboratory scale and the knowledge
focus on waste minimization and water conservation in required for the scale-up of the same and efficient large-
recent years has also resulted in the production of scale operation is lacking (Adewuyi, 2001; Gogate,
concentrated or toxic residues. It is of utmost importance 2002; Mason, 2000). Hence, it may happen that the
to dispose off these residues in a proper manner as well new technologies have to be used only as a pretreatment
as to keep the concentration of chemicals in the effluent stage followed by the conventional biological oxidation
techniques. In this series of articles on the imperative
*Corresponding author. Tel.: q91-22-414-5616; fax: q91- technologies for the wastewater treatment, we have tried
22-414-5614. to concentrate on the oxidation technologies (operating
E-mail address: abp@udct.ernet.in (P.R. Gogate). at ambient conditions) operating both individually as
1093-0191/04/$ - see front matter ᮊ 2003 Elsevier Ltd. All rights reserved.
doi:10.1016/S1093-0191(03)00032-7
2. 502 P.R. Gogate, A.B. Pandit / Advances in Environmental Research 8 (2004) 501–551
well as in synergism with each other generally described al., 2000a; Zwinter and Krimmel, 2000; Arslan and
as the hybrid technologies. In the present work, the Balcioglu, 2001a; Gogate et al., 2002a). Moreover,
oxidation technologies operating at ambient conditions additional mass transfer resistances between the pollut-
individually will be discussed while in the next article ant and the oxidizing agents generally hamper the
hybrid techniques will be discussed. It should also be overall efficacy of the process especially for the ozon-
noted that there are other oxidation technologies as well, ation process. Free radicals are generated when ozone
such as hydrothermal oxidation processes (further clas- is used in combination with hydrogen peroxide or action
sified as wet air oxidation, sub-critical, critical and of ozone or hydrogen peroxide is supplemented by other
super-critical water oxidation processes) applied to vari- energy dissipating components such as use of UVysun
ety of model pollutants as well as actual wastewaters, light or ultrasound and these hybrid techniques have
but are not discussed in the present work as these been found to result in lower treatment times as com-
technologies are viable for highly concentrated effluents pared to any of the individual techniques (Weavers et
(COD load)40 000 ppm) to think in terms of return al., 2000; Fung et al., 2000a; Gogate et al., 2002a)
(energy recovery) or investment (high pressure equip- though the costyenergy efficiency will be dependent on
ments) and it is imperative to develop oxidation tech- the operating conditions and the type of the effluent.
nologies operating at ambient conditions, which can The discussion about the hybrid techniques will be
also be easily monitored without sophisticated instru- presented in details in the next article.
mentation for high temperatureyhigh pressure operation. Majority of these oxidation technologies, however,
The oxidation technologies discussed in the present fail to degrade the complex compounds completely,
work can be classified as advanced oxidation processes especially in the case of real wastewaters and moreover,
(Cavitation, Photocatalytic oxidation and Fenton’s cannot be used for processing the large volumes of
chemistry) and chemical oxidation (use of ozone and waste generated with the present level of knowledge
hydrogen peroxide) and these processes have the poten- about these reactors (e.g. Commenges et al. (2000)
tial to degrade the new toxic chemicals, bio-refractory have shown that cavitation has failed to give substantial
compounds, pesticides, etc. either partially or fully, but degradation in the case of real industrial effluent, where-
most importantly under ambient conditions. as similar results have been reported by Beltran et al.
Advanced oxidation processes are defined as the (1997) for the case of photocatalytic oxidation being
processes that generate hydroxyl radicals in sufficient applied to distillery and tomato wastewaters). Hence,
quantities to be able to oxidize majority of the complex these can be used to degrade the complex residue up to
chemicals present in the effluent water. These processes a certain level of toxicity beyond which the conventional
include cavitation (generated either by means of ultra- methods can be successfully used for further degradation
sonic irradiation or using constrictions such as valves, (Rachwal et al., 1992; Beltran et al. 1999a,b; Engwall
orifice, venturi, etc. in the hydraulic devices (Adewuyi, et al., 1999; Kitis et al., 1999; Mastin et al., 2001). It
2001; Gogate, 2002; Gogate and Pandit, 2001; Gonze should also be noted that the efficacy of conventional
et al., 1999; Keil and Swamy, 1999; Pandit and Mohol- methods would also depend on the level of toxicity
kar, 1996; Moholkar et al., 1999a; Senthilkumar and reached in the pretreatment stages, using the oxidation
Pandit, 1999), photocatalytic oxidation (using ultraviolet techniques. Thus, it is important to select proper pre-
radiationynear UV lightySun light in the presence of treatment technique to improve the overall efficiency of
semiconductor catalyst (Bhatkhande et al., 2002; Blake, the wastewater treatment unit. In this work, the above-
1997; Herrmann, 1999; Yawalkar et al., 2001) and mentioned five oxidation techniques have been dis-
Fenton chemistry (using reaction between Fe ions and cussed, also highlighting the work required for
hydrogen peroxide, i.e. Fenton’s reagent (Venkatadri transferring the efficient laboratory scale technique to
and Peters, 1993; Bigda, 1995, 1996; Nesheiwat and large-scale operations.
Swanson, 2000). Hydroxyl radicals are powerful oxidiz-
ing reagents with an oxidation potential of 2.33 V and 2. Cavitation
exhibits faster rates of oxidation reactions as compared
to that using conventional oxidants like hydrogen per- Cavitation is defined as the phenomena of the for-
oxide or KMnO4 (Gogate et al., 2002a). Hydroxyl mation, growth and subsequent collapse of microbubbles
radicals react with most organic and many inorganic or cavities occurring in extremely small interval of time
solutes with high rate constants (Glaze et al., 1992; von (milliseconds), releasing large magnitudes of energy
Sonntag, 1996; Hoigne, 1997). (Lorimer and Mason, 1987; Mason and Lorimer, 1988;
Chemical oxidation technologies constitute the use of Suslick, 1990; Shah et al., 1999). It should also be
oxidizing agents such as ozone and hydrogen peroxide, noted that though the release of energy is over very
but exhibit lower rates of degradation as compared to small pocket, cavitation events occur at multiple loca-
the processes based on the free radicals (Echigo et al., tions in the reactor simultaneously (some indication
1996; Weavers et al., 1998; Freese et al., 1999; Fung et about the number of cavities existing in the reactor at a
3. P.R. Gogate, A.B. Pandit / Advances in Environmental Research 8 (2004) 501–551 503
Fig. 1. Schematic representation of the equipments based on acoustic cavitations.
given time can be obtained using theoretical modelling question as well as the degree of cavitation intensity,
of bubble dynamic equations as shown by Naidu et al. which in turn depends on the operating conditions of
(1994) though it is extremely difficult to quantify the the sonochemical reactor. There have been a number of
exact number of cavitation events using experiments) illustrations in the literature, dealing with the mecha-
and hence the overall effects are spectacular. Some of nisms of oxidation of different pollutants using cavita-
the important effects of cavitation can be given as the tion including some review articles (Adewuyi, 2001;
generation of hot spots, release of highly reactive free Dewulf et al., 2001; Hoffmann et al., 1996; Hung and
radicals, continuous cleaning as well as increase in the Hoffmann, 1999; Weavers et al., 2000; Sivakumar et
surface area of the solid catalysts, enhancement in the al., 2002; Shah et al., 1999; Suslick and Hammerton,
mass transfer rates due to turbulence generated as a 1986; Suslick et al., 1990).
result of acoustic streaming etc. (Miller, 1950; Suslick
1990; Suslick et al., 1986; Pestman et al., 1994; Shah 2.1. Acoustic cavitation
et al., 1999; Pandit and Moholkar, 1996; Thompson and
Doraiswamy, 1999; Adewuyi, 2001). Cavitation is clas- In the case of acoustic cavitation, cavitation is effect-
sified into four types based on the mode of generation ed using the high frequency sound waves, usually
viz. Acoustic, Hydrodynamic, Optic and Particle, but ultrasound, with frequencies in the range of 16 kHz–
only acoustic and hydrodynamic cavitation has been 100 MHz. Alternate compression and rarefaction cycles
found to be efficient in bringing about the desired of the sound waves results in various phases of cavita-
chemical changes whereas optic and particle cavitation tion such as generation of the bubbleycavity, growth
are typically used for single bubble cavitation, which phase and finally collapse phase releasing large amount
fails to induce chemical change in the bulk solution. of energy locally (Suslick, 1990; Lorimer and Mason,
The destructionyoxidation of pollutants using cavita- 1987; Shah et al., 1999).
tion is usually described by two approaches viz. free
radical attack (Nagata et al., 2000) has reported a 2.1.1. Reactors used for the generation of acoustic
substantial decrease in the rates of degradation of cavitation
chlorophenols in the presence of radical scavengers and Fig. 1 gives the schematic representation of the
confirmed the involvement of free radicals in the overall commonly used equipments based on acoustic cavita-
destruction process) and pyrolysis (Kang and Hoffmann, tion. The detailed discussion about the different types
1998) have reported that destruction of MTBE follows of sonochemical reactors has been made earlier (Pandit
the pyrolysis route and therefore, no decrease in the and Moholkar, 1996; Shah et al. 1999; Thompson and
rates of degradation is observed in the presence of Doraiswamy, 1999; Keil and Swamy, 1999; Gogate et
radical scavengers). The controlling mechanism for the al., 2001a, 2002b). Typically, the equipments with high-
destruction is usually dependent on the pollutant in er dissipation area give larger energy efficiency at
4. 504 P.R. Gogate, A.B. Pandit / Advances in Environmental Research 8 (2004) 501–551
similar levels of the supplied input energy (more amount may become uneconomical at much higher frequen-
of energy of the total supplied electrical energy is cies of irradiation (Mason, 1990) due to the fact that
converted for positive effects (Gogate et al., 2001a, significant quantity of the supplied energy will be
2002b)). Also, use of equipments based on multiple used only in the generation of the cavities. Use of
frequenciesymultiple transducers (device used for con- multiple frequencies (using multiple transducers irra-
verting supplied electrical energy into sound energy and diating multiple frequencies; Sivakumar et al. (2002)
generate ultrasound with frequency in the range of 15 have described a design where 6 transducers in total
kHz–10 MHz) has been reported to be more beneficial have been attached on the opposite faces of a rectan-
as compared to the equipments based on a single gular cross-section irradiating 25 and 40 kHz either
frequency (Hua et al., 1995a; Thoma et al., 1997; individually or simultaneously) produces more
Sivakumar et al., 2002; Gogate et al., 2001a, 2002b). intense cavitation (Tatake and Pandit, 2002) as indi-
Ultrasonic horns vibrating in radial directions, which cated by the higher values of the pressure pulse
also gives additional advantage of better energy dissi- generated at the end of cavitation event for the
pation due to larger irradiating area (Dahlem et al., multiple frequency operation as compared to the
1998, 1999), is another new development with promis- single frequency operation and hence results in higher
ing future for medium to large-scale applications, but yields of transformation (Sivakumar et al., 2002).
more work is required in terms of testing these equip- Thus, dual or triple frequency reactors should be
ments for operation at high frequency and high power used which will also give similar results to a single
dissipation. very high frequency transducer, but with minimal
problems of erosion (Moholkar et al., 1999b), Mohol-
2.1.2. Optimum operating parameters for sonochemical kar and Warmoeskerken (2000) have also indicated
reactors that by adjusting the magnitude of the frequency in
The optimum considerations for operating and geo- the multiple frequency operation, the collapse of the
metric parameters of the sonochemical reactors can be cavities can be directed at a region away from the
given as: surface, so that the erosion of the transducer surface
will be less). Also, larger volumes of effluent can be
1. Higher frequencies of operation are suited for effec- effectively treated due to increased cavitationally
tive destruction of pollutants (until an optimum value active volume for multiple transducers (Sivakumar
(Hua and Hoffmann, 1997; Hung and Hoffmann, et al., 2002; Gogate et al., 2002b).
1999) and the magnitude of optimum frequency also 2. Greater energy efficiency has been observed for
depends on the type of the effluent and the operating ultrasonic probes with higher irradiating surface,
conditions), however, it is difficult to operate at (lower operating intensity of irradiation) which
higher frequencies greater than 200 kHz (Mason, results into uniform dissipation of energy (Gogate et
1992; Berlan and Mason, 1992). It should also be al., 2001a). Thus, for the same power density (power
noted that there are few illustrations where higher input into the system per unit volume of the effluent
frequencies are used for the destruction of pollutants to be treated), power input to the system should be
(Petrier et al., 1992, 1996; Francony and Petrier, through larger areas of irradiating surface.
1996; Petrier and Francony, 1997a,b; Hua and Hoff- 3. The physicochemical properties of the liquid medium
mann, 1997; Hung and Hoffmann, 1999), but the (vapor pressure, surface tension, viscosity, presence
scale of operation is typically in the range of 50– of impuritiesygases etc.) also crucially affect the
500 ml and hence the scale-up ratio will be substan- performance of the sonochemical reactors. The initial
tially high, indicating the uncertainty in the design size of the nuclei generated, cavitations inception and
of reactors. Continuous operation with high frequen- number of cavities produced depends mainly on these
cies at larger scale of operation (and hence at higher liquid properties. Cavitation inception can be defined
power dissipation levels), leads to an erosion of the as the minimum power required for the onset of
transducer surface (due to lower collapse time of the cavitation process, i.e. formation of the cavities and
cavitating bubbles (Hung and Hoffmann, 1999) as this should be as lower as possible so that the
well as more number of cavitational events (Crum, effective energy available for the growth of the
1995) at higher frequencies of operation, there is a cavities is larger (the total supplied energy is utilized
likelihood of higher erosion rates of the transducer for generation of cavitation referred as cavitational
surface as compared to that obtained at lower fre- inception and for growth of cavity followed by
quency of irradiation), which makes it practically subsequent collapse) leading to a higher collapse
unfeasible to operate sonochemical reactors under pressure pulse (Mason, 1990; Gogate and Pandit,
these conditions. Moreover, the power required for 2000a). The cumulative pressureytemperature pulse
the onset of cavitation increases with an increase in generated as a result of cavitation is the product of
the frequency of irradiation and hence the process pulse generated due to the collapse of single cavity
5. P.R. Gogate, A.B. Pandit / Advances in Environmental Research 8 (2004) 501–551 505
(lower initial cavity size results in higher collapse the system in question. More detailed discussion
pressureytemperature pulse (Gogate and Pandit, about the effect of presence of the catalystygases on
2000a)) multiplied by the number of cavities gener- the cavitation events have also been given in the next
ated in the reactor. It is hence advisable to have large paper of the series.
number of cavitation events occurring in the reactor 6. Rate of the destruction is inversely proportional to
with lower initial size of the cavitating nuclei. Thus, the operating temperature, which also affects the
the liquid phase physicochemical properties should vapor pressure of the medium, and hence lower
be adjusted in such a way so as to lower the cavitation temperatures (typically of the order of 10–15 8C)
inception threshold resulting in easy generation of will be preferred (Suslick et al., 1997; Sivakumar et
cavities and at the same time increasing the number al., 2002). However, if the dominant mechanism of
of cavities generated with lower initial size. The destruction is pyrolysis, e.g. destruction of tri-chlo-
effect of various physicochemical properties has been roethylene (Drijvers et al., 1999), this will not be
discussed in detail in some of our earlier works true.
(Gogate, 2002; Gogate et al., 2001b).
Mason and Cordemans, (1998) have also given the
4. The rate constant for the sonochemical degradation
following 10 recommendationsysteps in the optimization
of the pollutants is higher at lower initial concentra-
of an ultrasonic process.
tion of the pollutant and hence pre-treatment of the
waste stream may be done in terms of diluting the 1. Make cavitation easier by the addition of solids or
stream for enhanced cavitational effects. However, gas bubbles to act as nuclei.
an analysis must be done comparing the positive 2. Try entraining different gases or mixture of gases.
effects due to decreased concentration and the nega- 3. Try different solvents for different temperature rang-
tive effects associated with lower power density to es and cavitation energies.
treat larger quantity of pollutant (extent of degrada- 4. Optimize the power required for the reaction.
tion is directly proportional to power density up to 5. When using a solid–liquid system, do not charge
an optimum value (Sivakumar and Pandit, 2001)). all the components in the reactor at once.
5. Aeration and addition of catalyst such as TiO2, 6. If possible, try to homogenize two-phase systems as
NiSO4, CCl4, Fe2q yFe3q, CuSO4 and also salts such much as possible.
as NaCl, significantly enhances the extent of degra- 7. Try different shapes (diameters and volumes) for
dation (Ingale and Mahajani, 1995; Mason et al., the reactor.
1996; Seymore and Gupta, 1997; Shirgaonkar and 8. It can be better (but not always) to avoid standing
Pandit, 1997; Hung and Hoffmann, 1998; Nagata et wave conditions by performing sonochemical reac-
al., 2000; Pandit et al., 2001; Sivakumar et al., 2002; tions under high power conditions with mechanical
Gogate et al., 2002c). Presence of gases (oxygen, stirring.
ozone) or gaseous mixtures such as AryO3 mixture 9. Try to transform a batch system into a continuous
also increases the efficiency of acoustic cavitation in one, wherever possible.
some cases (Hart and Henglein, 1985; Olson and 10. Choose conditions, which allow comparisons
Barbier, 1994; Entezari et al., 1997; Weavers et al., between different sonochemical reactions.
1998, 2000). It should be noted that it is difficult to
generalize and optimize the effect of the presence of 2.1.3. Overview of work done in recent years and scope
gases andyor catalyst, as the effect is usually not for future work
unidirectional. On the one hand, where the presence The use of sonochemical reactors for the wastewater
of catalyst enhances the number of cavitation events applications is not new to the researchers and there are
by providing additional nuclei, it also acts as a barrier many illustrations in the literature (Nagata et al., 1996;
for the propagation of sound wave thereby decreasing Thoma et al., 1998; Petrier et al., 1998; David et al.,
the effective energy dissipation into the system. Thus, 1998; Gondrexon et al., 1999; Cyr et al., 1999; Suri et
optima of catalyst concentration may be obtained al., 1999; Colussi et al., 1999; Joseph et al., 2000;
depending on the system under investigation (Gogate Destaillats et al., 2000, 2001; Grieser et al., 2000; Yim
et al., 2002a). It may also happen, however, that not et al., 2000; Tauber et al., 2000; Clark et al., 2000;
all sonochemical reactions are enhanced by the pres- Schramm and Hua, 2001; Teo et al., 2001; Gaddam and
ence of catalyst and hence for a particular application, Cheung, 2001; Pandit et al., 2001; Yim et al., 2001)
laboratory scale experiments are required unless data where they have been successfully used for the degra-
are available in the literature with the specified dation of variety of compounds at different scales of
catalyst. Similarly, for the case of presence of gases, operation. It should be noted that these illustrations are
the observed effect depends on the solubility, thermal only very few of the vast amount of literature available
conductivity, polytropic index of the gas and hence on this subject, with studies varying in terms of target
the optimal conditions will strongly be dependent on chemical studied, type of the equipment and operating
6. 506 P.R. Gogate, A.B. Pandit / Advances in Environmental Research 8 (2004) 501–551
conditions. Table 1 depicts some of the representative ● Consequences of Cly ions.
applications of sonochemical reactors to the waste water Further, it is also important to consider the cost of
treatment illustrating the type of equipment used with applying ultrasonic irradiation for the destruction pro-
the scale of operation, the chemicals used in the study cess on an industrial scale. The current costs for the
and the important findings of the work. It can be seen cleaning of contaminated ground water using acoustic
from the table that majority of the work is on a cavitations are in the order of magnitude, higher than
laboratory scale and large quantum of work needs to be those by an air strippingyactive carbon process (Peters,
done both in terms of the design strategies for the scale- 2001). Thus, it is important to either find an alternative
up and feasibility of the operation of transducers at means for generating cavitation energy efficiently or use
higher levels of power dissipation, before successful acoustic cavitation (generated by ultrasonic irradiation)
application of sonochemical reactors are feasible at an in combination of other methods such as photocatalytic
industrial scale. oxidation (Shirgaonkar and Pandit, 1998; Gogate et al.,
It is also important to stress at this juncture that 2002a), wet air oxidation (Ingale and Mahajani, 1995;
almost all the studies are with model pollutants and Dhale and Mahajani, 1999, 2001) etc. Another gray
may or may not give similar degradation rates when area in the prospective use of acoustic cavitation for
applied to real effluents containing a variety of com- large-scale wastewater treatment is the problems asso-
pounds. Recently, Peters (2001) has tried to tackle this ciated with high frequency transducers arising out of
situation. Peters (2001) has studied the sonolytic deg- the mechanical constraints from the construction of
radation of 1,2-dichloroethane, prepared in deionized transducers (the maximum transfer efficiency is only
water (model constituent solution) and also in the obtained when the transducer is driven at resonating
natural sample (concentration of approx. 350–390 mgy frequency and for high frequencies, it is difficult to
l with other VOC amounting to 80–85 mgyl), reporting obtain proper material of construction for the transduc-
that the destruction was complete within 120 min for ers). Also, the threshold intensity required is substan-
all the components (at conditions of operating frequency tially large for the higher frequencies resulting in higher
of 361 kHz, calorimetric power dissipation of 52 W, power consumption and most importantly, it is very
volume of effluent as 200 ml, operating pH of 6.28 and difficult to operate efficiently at conditions of high
temperature of 9 8C) and also for some of the interme- frequencies and high-energy dissipation. It should also
diates formed in the destruction process (e.g. trans-1,2- be noted that due to higher frequency of operation,
dichloroethane). However, in another recent work, higher number of free radicals will indeed be generated,
Commenges et al. (2000) have reported that ultrasonic but at the same time lower collapse time of the cavitat-
irradiation failed to induce any decrease in the toxicity ing bubbles gives lesser contact time for the chemical
and COD for a concentrated sample of the effluent from constituents (Hung and Hoffmann, 1999) and also the
a paper mill (at operating conditions of operating other drawbacks as discussed earlier nullify the advan-
frequency as 500 kHz, calorimetric power dissipation tage of the higher rates of free radical generation. One
as 150 kWym3 and operating temperature as 20 8C). of the alternatives for high frequency transducers is the
This may be possibly attributed to the high concentration use of multiple frequencyymultiple transducer reactors
of the complex refractory materials. Dilution of the with lower individual frequency of irradiation (problems
stream resulted in approximately 17% COD reduction; of erosion, higher cavitational inception will not be
still sonication is not a favored method for these type there), which has been reported to give much better
of effluents. Thus, question still remains; can the highly results in terms of the energy efficiency as well as the
efficient laboratory scale technique for model constitu- cavitational yields (net chemical change per unit sup-
ent solutions be feasible for the degradation of real plied electrical energy) as discussed in detail in the
effluents? The detailed analysis, with recommendations earlier sections.
for the future work for transferring the well established
laboratory scale technique to industrial scale has been 2.2. Hydrodynamic cavitation
presented in the earlier work (Gogate, 2002). Future
work should also be directed in terms of understanding One of the alternative techniques for the generation
the detailed role of following water parameters in of cavitation is the use of hydraulic devices where
determining the efficiency of cavitation process as a cavitation is generated by the passage of the liquid
technique for the treatment of real effluents, containing through a constriction such as valve, orifice plate,
a complex mixture of compounds: venturi etc. (Gogate and Pandit, 2001).
● Role of inorganic components and gases. 2.2.1. Reactors used for generation of hydrodynamic
● Influence of water components on the pH during the cavitation
sonication process. Fig. 2 shows some of the equipments used for the
● Influence of precipitates and particles. generation of hydrodynamic cavitation. The cavitation
7. Table 1
Some representative illustrations about use of ultrasonic irradiation for wastewater treatment
Sr. no. Reference Type of equipment and experimental details Highlights of the work
1 Bhatnagar and Cheung (1994) Ultrasonic horn type of reactor with operating First order degradation kinetics was observed
frequency of 20 kHz and power dissipation for all the chemicals and rate constants for
into the solution of 190 W. Temperature is each component have been given. Rate
maintained in the range 20–25 8C. Capacity constant is inversely proportional to the vapor
P.R. Gogate, A.B. Pandit / Advances in Environmental Research 8 (2004) 501–551
of the reactor is 2 l. Pollutant studied: Aqueous pressure of the constituent; a result similar to
solutions of methylene chloride, chloroform, the effect of temperature on sonochemical
carbon tetrachloride, 1,2-di-chloroethane, reaction rates. pH of solution continuously
1,1,1-trichloroethane, trichloroethylene and decreases due to the formation of HCl
per-chloroethylene during the sonication process
2 Price et al. (1994) Ultrasonic horn system operating at irradiation Dichlorobenzne can be degraded completely
frequency of 22 kHz and intensity of irradiation in approximately 40–50 min of reaction time
in the range 11–40 Wycm2. Capacity of at power intensity of 39 Wycm2. Use of higher
reactor 500 ml, operating temperature of intensity leads to faster reaction rates over
20 8C. Pollutant studied: 1,4-dichlorobenzene, the complete range of intensity studied in the
chlorobenzene, naphthalene, Anthracene, work. First order kinetics was observed and
pyrene rate constant values have been given for
different compounds
3 Catallo and Junk (1995) Ultrasonic horn type system (no information The work concentrates mainly in identifying
regarding operating frequency and power the dechlorination products and the other
dissipation) with continuous sparging of intermediates and different possible schemes
Argon, capacity of the reactor: 50–1000 ml. for the degradation have been presented
Operating temperature in the range of 4–
12 8C. Chemicals studied: Chlorpyrifos, 2-
chlorobiphenyl, 2,4,8- trichlorodibenzofuran,
lindane, hexachlorobenzene, aldrin and
complex mixture of chlorinated olefins,
paraffins and aromatics (real life situation)
4 Francony and Petrier (1996) Cylindrical jacketed reactor with power Rate of disappearance is more for 500 kHz as
dissipation of 30 W and ultrasonic irradiation compared to 20 kHz (almost double time is
at 20 and 500 kHz. Operating temperature of required for complete disappearance at 20 kHz
25 8C and capacity of 200 ml. Pollutant operation). Detailed mechanism and the
studied: carbon tetrachloride different reaction products have been identified.
Addition of 1-butanol does not change the
rates of degradation indicating that free radicals
are not formed during the reaction and
pyrolysis is the controlling mechanism
5 Yoo et al. (1997) Sonochemical reactor with multiwave Pseudo first order kinetics with the order of the
generator and barium titanate oscillator rate of degradation as propionic acid
operating at 200 kHz and power dissipation -n-butyric acid-n-valeric acid. The order of
of 6 Wycm2 per unit volume. Capacity of the n-valeric acid degradation rates is nitrogen
507
reactor is 150 ml and operating temperature -air-argon. Degradation is suppressed by the
8. 508
Table 1 (Continued)
Sr. no. Reference Type of equipment and experimental details Highlights of the work
is 20"2 8C. Operation with sparging different addition of radical scavengers (t-butanol).
gases viz nitrogen, air and argon. Pollutant Reaction is 80% due to the free radical
studied: propionic acid, n-butyric acid, formation and 20% due to pyrolysis. Rate
n-valeric acid constant increases with a decrease in the
pH of the solution. For the mixture of three
P.R. Gogate, A.B. Pandit / Advances in Environmental Research 8 (2004) 501–551
acids, reduced rates of degradation has been
observed. TOC reduction is less as compared
to the rate of n-valeric acid removal indicating
that it is not completely mineralized
6 David et al. (1998) Branson sonifier 450 generator with titanium The treatment at high frequency is much more
probe system operating at 20 kHz and power efficient (approx. 3 times initial rates of
input into the system of 20 W. Another system degradation). Kinetics of formation of
with high frequency irradiation at 482 kHz different products has been presented. For
and same power dissipation. Operating 3-chloroaniline the degradation rates for
temperature of 20 8C and capacity of 100 ml. 482 kHz were approximately 8 times more as
Pollutant studied: Chlorpropham and compared to the lower frequency operation.
3-chloroaniline Kinetics for the main sonoproducts at 482 kHz
has been given
7 Gonze et al. (1999) Bath type reactor with transducer fitted at the Review of earlier work for destruction of
bottom of tank (driving frequency of 500 kHz, chlorinated aliphatic and aromatics in terms of
variable power input in the range, 0–100 W), reaction mechanism and intermediates formed
reactor capacity: 1000 ml. Pollutant studied: have been presented. First order kinetics for
Sodium pentachlorophenate degradation with higher rate constant at more
power input, toxicity analysis for different
bacterias have been presented showing
conclusively that ultrasonic irradiation can be
used as pretreatment for biological oxidation
8 Weavers et al. (2000) Different reactor systems, orthoreactor Rate constants for degradation under different
ultrasonic transducer (capacity of 640 ml, conditions of irradiation have been given and
intensity 1.89 Wycm2) operating at 515 kHz also as a function of initial concentration of
and direct immersion system (capacity of 50 pollutant. Rate increases with an increase in
ml, intensity 55.8 Wycm2) and tube frequency, power density and decrease in
resonator (capacity of 1750 ml, intensity initial concentration of pollutant. Sonication
1.24 Wycm2) both operating at 20 kHz. coupled with ozonation was found to be
Pollutant studied: Pentachlorophenol favorable at lower frequencies only. Reaction
mechanism has been discussed with the
analysis of the intermediates
9 Nagata et al. (2000) A multiwave ultrasonic generator operating at First order decay kinetics was observed with
200 kHz frequency with a power input of complete degradation in approximately 1 h
200 W. Capacity of the reactor: 150 ml. in the presence of argon; rate of degradation
Pollutant studied: 2-, 3-, 4-chloro-phenol (CP) faster in presence of Argon as compared to air.
and pentachlorophenol Decomposition rates for 3 CP more as
9. Table 1 (Continued)
Sr. no. Reference Type of equipment and experimental details Highlights of the work
compared to 2 and 4 due to favorable
alignment for attack of free radicals. t-BuOH
acts as a radical scavenger thereby decreasing
the rates of degradation. Detailed analysis of
the reaction mechanism and sites has been
P.R. Gogate, A.B. Pandit / Advances in Environmental Research 8 (2004) 501–551
given considering degradation of chlorophenol.
Optimum amount of Feqq enhances the rate of
reaction by about two times
10 Gogate et al. (2001a) Ultrasonic horn with driving frequency of Existence of equilibrium or limiting
22.7 kHz and power rating of 600 W, concentration up to which degradation can be
capacity of 100 ml and Ultrasonic bath achieved effectively using ultrasound. Reaction
(frequency of 22 kHz and power rating of rate increases with same power dissipation
120 W), capacity of 750 ml; Dual frequency over a wider area, increase in the frequency
flow cell (frequency of 25 and 40 kHz, of irradiation and by the use of multiple
power input of 120 W per side), capacity: frequencies. Aeration results in enhanced rates.
1500 ml; Triple frequency flow cell Novel reactors with an aim of increasing
(frequency of 20, 30 and 50 kHz operating the turbulence, cavitational intensity and zone
in multiple combinations, power input of of influence of the transducers have been
150 W per side), capacity: 7000 ml. depicted
Pollutant used: Formic acid
11 Dewulf et al. (2001) Undatim reactor with operating frequency of Reaction rate increases with decrease in the
520 kHz and power dissipation of 9.4 W, initial concentration for both TCE and CB.
capacity of 200 ml, operating conditions of Mixture of two pollutants slightly decreases
30 8C temperature and pH of 7, Micromolar the rate constants. Model has been developed
concentrations of effluents. Chemicals studied: for predicting rates of degradation considering
trichloroethylene (TCE) and free radical attack in combination with
chlorobenzene (CB) pyrolysis as the two simultaneous mechanisms.
At concentrations above 1000 mM, pyrolysis
is the dominant mechanism whereas at lower
concentrations 1–5 mM, radical mechanisms
also plays a crucial role
12 Peters (2001) Experiments with different irradiation Chloride yield increases with increase in the
frequencies in the range 20–1086 kHz with frequency of irradiation (in the range 20–
sample volumes of 200–500 ml. Pollutant 618 kHz), increase in the power input to the
studied: Samples of ground water with system and decrease in initial concentration
majority component as 1,2-dichloroethane of pollutant. Mixture of chloro-compounds
509
10. 510
Table 1 (Continued)
Sr. no. Reference Type of equipment and experimental details Highlights of the work
(350–390 mgyl) and other VOC amounting also gets degraded under sonication within
to 80–85 mgyl. 60–120 min time. Degradation for natural
wastewater follows different path as compared
to pure solutions and associated problems
(in terms of role of inorganic components and
P.R. Gogate, A.B. Pandit / Advances in Environmental Research 8 (2004) 501–551
gases, water components, precipitates and
particles etc.) have been discussed
11. P.R. Gogate, A.B. Pandit / Advances in Environmental Research 8 (2004) 501–551 511
Fig. 2. Schematic representation of the equipments based on hydrodynamic cavitations.
intensities generated in the hydrodynamic cavitation Higher diameters are recommended for applications
reactors are lower as compared to the acoustic counter- which require intense cavitation, e.g. degradation of
parts, and the design of the reactors in terms of the complex chemicals such as Rhodamine B (Sivakumar
operating and geometric conditions must be critically and Pandit, 2002) whereas lower diameters with large
done in order to suit a particular application. Orifice number of holes should be selected for applications
plate set-up (Gogate et al., 2001a; Gogate and Pandit, with reduced intensity, e.g. KI decomposition
2001) offers more flexibility in terms of selection of (Vichare et al., 2000).
the different orifice plate configurations (differing in 4. Percentage free area offered for the flow (Ratio of
number and diameter of holes (Gogate, 2002)) as the free area available for the flow, i.e. cross-
compared to devices based on the use of throttling sectional area of holes on the orifice plate to the
valves. total cross-sectional area of the pipe): Lower free
areas must be used for producing high intensities of
2.2.2. Optimum operating conditions cavitation and hence the desired beneficial effects
The optimization should be done in terms of the inlet (Vichare et al., 2000; Gogate and Pandit, 2000b).
pressure into the system, geometry of the constriction
used for the generation of cavitation and physicochem- 2.2.3. Overview of work done in recent years and scope
ical properties of the liquid medium. Some of the for future work
important considerations in this regard can be given as
It should be noted that there are not many reports
follows (Vichare et al., 2000; Senthilkumar et al., 2000;
depicting the use of these equipments for wastewater
Gogate and Pandit, 2000b, 2001; Gogate, 2002):
treatment (Table 2), but these offer higher energy
1. Inlet pressure into the systemyRotor speed depending efficiencies, more flexibility and higher potential for
on the type of equipment: Use increased pressures or scale-up as compared to their acoustic counterparts
rotor speed, but avoid supercavitation by operating (Gogate et al., 2001a). Recently, Sivakumar and Pandit
beyond a certain optimum value (Vichare et al. 2000; (2002) have used orifice plate hydrodynamic cavitation
Shirgaonkar, 1997). set-up for degradation of rhodamine B and reported that
2. Physicochemical properties of the liquid and initial the cavitational yields are higher as compared to all the
radius of the nuclei: The guidelines for selecting the sonochemical equipments (ultrasonic horn, ultrasonic
physicochemical properties so as to achieve lower bath, dual frequency flow cell) used in their study.
initial sizes of the nuclei are similar to those used Kalumuck and Chahine (2000) have studied the destruc-
for the acoustic cavitation. tion of p-nitrophenol in re-circulating flow loops using
3. Diameter of the constriction used for generation of a variety of cavitating jet configurations and operating
cavities, e.g. hole on the orifice plate: Optimization conditions and have shown that, indeed, hydrodynamic
needs to be carried out depending on the application. cavitation degraded p-Nitrophenol. Submerged cavitat-
12. 512
Table 2
Analysis of the work done in the area of application of hydrodynamic cavitation reactors to wastewater treatment
Sr. no. Reference Type of equipment and experimental details Main features of the work
1 Suslick et al. (1997) Micro jet fluidizers operating at conditions of The cavitation inception was obtained at inlet
1.24 kbar liquid inlet pressure and velocities pressure of 150 bar indicated by significant
of 190 mys. The reaction solution is first release of iodine. The reaction rate further
sparged with high purity argon or AryHe increases linearly with an increase in the
P.R. Gogate, A.B. Pandit / Advances in Environmental Research 8 (2004) 501–551
mixtures and light protected to prevent CCl4 upstream liquid pressure over the range of
photodecomposition and then injected into 200–1500 bar as studied in the work. Iodine
the pressurized reservoir through a self sealing liberation also increases with decrease in the
septum. A portion of the reaction solution is thermal conductivity of the dissolved gases at
pressurized by a large pneumatically driven constant specific heat ratio. The result can be
pump into an interaction chamber, where attributed to the principles of hot-spot theory,
two pulsed flows are redirected at each other which suggest that the maximum temperature
through jewel orifices with velocities of reached in collapsing bubbles increases with a
190 mys controlled by a back pressure decrease in the thermal conductivity. Further
regulator. Cavitation occurs when there is the rate of iodine liberation was also found to
sufficient turbulence upon the liquid jet impact increase with a decrease in the temperature
or a sufficient pressure drop is created as the of liquid bulk due to lower vapor pressures
stream passes through the orifices. High and hence operation at lower temperatures is
velocity pumping results into heating of the favored
liquid medium and hence the reactor along
with the accessories is immersed in a
thermally equilibrated bath. Pollutant studied:
Potassium iodide
2 Kalumuck and Chahine (2000) Closed loop circuit with contaminant Cavitating jet set-up gives approximately 20
pumped with a triplex positive displacement times more rates of degradation as compared
pump (4.5 galymin and 1000 psi pressure). to the ultrasonic horn (irradiating frequency of
Multiple orifice plates in the re-circulation 15.7 kHz and power density of 0.36 Wyml)
line one after another in order to produce and the oxidation efficiency (mg degraded per
intense cavitation. Capacity of the reactor: unit energy supplied) is almost 25 times more
6.5 l operated in re-circulating mode. for the cavitating jets. Optimum operating
Pollutant studied: p-Nitrophenol temperature was found to be 42 8C. Lower
pH and cavitation number (higher inlet pressure
at same pressure drop across the nozzle)
favors the degradation
3 Sivakumar and Pandit (2001)* The set-up consists of a closed loop circuit For same flow area, plate with larger number of
comprising of a holding tank of 50 l volume, small diameter holes gives more extent of
a centrifugal pump (2900 rpm, 5.5 kW, degradation as compared with plate with
Calama Industries Ltd, India), control valve smaller number of larger diameter holes. The
and flanges to accommodate the orifice observed results have been explained on the
plates. Liquid is pumped from the storage basis of frequency of turbulence for the two
13. Table 2 (Continued)
Sr. no. Reference Type of equipment and experimental details Main features of the work
tank and is re-circulated through a main line cases. The present set-up of hydrodynamic
housing the orifice plates. The cavitating cavitation using multiple hole orifice plates has
conditions are generated just after the orifice been found to give cavitational yields, which
plates in the main line. Different orifice plates are two times higher than the best acoustic
with different free areas for flow and also cavitation device (Dual frequency flow cell with
P.R. Gogate, A.B. Pandit / Advances in Environmental Research 8 (2004) 501–551
different combinations of number of holes capacity of 1.5 l) as discussed earlier.
and diameter of hole for same free area have Moreover, the capacity of the reactor in the
been used. The holding tank is provided with present case (50 l) is also 33 times higher as
cooling jacket to control the temperature of compared to the largest ultrasonic equipment
the circulating liquid. Pollutant studied: tested indicating easier scaleup options
Rhodamine B (a typical component of dyes
industry effluent)
*
Vichare et al. (2000) have also obtained similar results with experimentation in the same set-up but with the model reaction of decomposition of potassium iodide.
513
14. 514 P.R. Gogate, A.B. Pandit / Advances in Environmental Research 8 (2004) 501–551
Table 3
Comparison of different cavitational reactors using a model reaction (Gogate et al. 2001a)
Equipment Supplied Volume Energy Cavitational yield per
electrical power used efficiency unit power density
consumption (W) (ml) (%) gy(Jyml)
Dakshin horna 240 50 3.04 3.53 E-9
Dakshin batha 120 500 38.86 5.83 E-7
Ace horna 10% 40 50 15.43 1.39 E-9
20% 80 50 16.77 5.25 E-9
30% 120 50 15.9 5.48 E-9
Flow cella 25 kHz 120 1500 43.05 6.21 E-7
40 kHz 120 1500 26.97 5.85 E-7
25q40 kHz 240 1500 33 9.12 E-7
High pressure homogenizer (5000 psi)b 2090 2000 54.4 7.38 E-5
High speed homogenizerb 105 1500 43.07 6.645 E-7
Pilot plant scale (Orifice plates)b % free areas2.28% 5500 50 000 59.58 2.48 E-4
% free areas9.14% 5500 50 000 60.8 1.90 E-4
a
Equipment based on acoustic cavitation.
b
Equipment based on hydrodynamic cavitation.
ing liquid jets were found to generate a two-order of More work is indeed required both on theoretical
magnitude increase in energy, the efficiency compared front as well as on the experimental front for better
to the ultrasonic horn. understanding of the phenomena and subsequent design
Table 3 shows the energy efficiency and cavitational methodology. The important issues that need to be
yield for different reactors for the model reaction of studied are as follows:
decomposition of KI. It can be seen from the table that
the desired chemical change for a given amount of 1. Realistic modelling of the turbulence phenomena,
electrical energy supplied to the system as well as the which can then be used to model the cavityybubble
energy efficiency (ratio of the energy transferred into dynamics, either in isolation or in the form of cavity
the system to the supplied electrical energy) is higher clusters in high velocity flow. The modern sophisti-
for the hydrodynamic cavitation reactors. It should be, cated Computational fluid dynamics (CFD) codes
however, noted that the comparison made here is valid can be employed to get the flow field information,
only for a model reaction (decomposition of potassium i.e. mean and fluctuating velocity components, Reyn-
iodide), and the efficiencies of the various equipments olds stresses, turbulent pressure fluctuations etc. This
may or may not be the same for the variety of cavitation then can be used to understand the role of these flow
based transformations and also other applications. field parameters in altering the cavity dynamics.
Though hydrodynamic cavitation offers immense 2. It is necessary to develop user-friendly computer
potential and also higher energy efficiency and cavita- codes (similar to modern CFD codes) for the use of
tional yields as compared to acoustic counterpart at least engineers, which will allow them to change the
for the model reaction, use of these reactors is perhaps geometrical and operating parameters of the hydro-
lacking on larger scales. There exists only one commer- dynamic cavitation set-up, define physico–chemical
cial process (using hydrodynamic cavitation, though not properties of the chemical system under considera-
alone but in combination with UV irradiation and tion. These codes, with the help of bubbleycavity
oxidation with hydrogen peroxide), known as CAV- dynamics and the equilibrium chemistry at cavity
OX᭨, 1994 process, developed by Magnum Water collapse conditions, will then predict the expected
Technology Inc., California. Several contaminants of chemical effects avoiding trial and error type of
concern such as pentachlorophenol (PCP), benzene, experimentation for the engineers.
toluene, ethyl benzene, xylenes, cyanide, phenol, atra- 3. Design and fabrication of different types of hydro-
zine have been successfully degraded to a significant dynamic cavitation set-up differing in the flow field,
extent. Case studies at pilot plant scale showed that the turbulence characteristics and geometry, which will
process is effective for a wide variety of effluents allow efficient large-scale operation for effective
obtained from various chemical industries. The process usage in wastewater treatment plants.
also needs to be tested for complex mixture of effluents 4. Laboratory and pilot plant studies with simulated
or real industrial wastewaters. waste to understand and address the scale-up issues,
15. P.R. Gogate, A.B. Pandit / Advances in Environmental Research 8 (2004) 501–551 515
such as alteration in the flow field and turbulence the adsorption of pollutants plays an important role in
characteristics due to the scale of operation. deciding the overall rates of degradation as usually the
adsorption step is the rate controlling (Xu et al., 1999).
Overall it can be said that, cavitation offers a potential It should be noted that the best photocatalytic perform-
alternative for the degradation of chemicals in the ances with maximum quantum yields have been always
wastewater treatment scheme where majority of the with titania. In addition, Degussa P-25 catalyst is the
conventional techniques fail to give substantial conver- most active form (hybrid mixture of rutile (approx.
sions. However, majority of the studies available in this 70%) and anatase forms) among the various ones
area are on a small scale and hence much of the work available and generally gives better degradation effi-
needs to be done before this dream is realized. ciencies, (Sakthivel et al., 2000; Yamazaki et al., 2001)
though in some cases pure anatase based forms of
3. Photocatalysis TiO2 such as Hombikat, PC-500 have also been reported
to be more efficient (Lindner et al., 1997; Ray and
The photocatalytic or photochemical degradation pro- Beenackers, 1997; Chen and Ray, 1998). Also, the
cesses are gaining importance in the area of wastewater photocatalytic activity of titanium dioxide can be
treatment, since these processes result in complete min- enhanced by using pretreatment with sulfuric acid (Yu
eralization with operation at mild conditions of temper- et al., 2002) or by increasing the cation strength, e.g.
ature and pressure. There are good reviews available on doping with platinum (Hufschmidt et al., 2002; Li et
this subject by Fox and Duley (1993), Legrini et al. al., 2002; Lia and Li., 2002).
(1993), Kamat (1993) and Hoffmann et al. (1995)
covering the analysis of the studies prior to 1995 and 3.1. Reactors used for photocatalytic oxidation
depicting basics of the processes including the mecha-
nism of oxidation of pollutants in detail. Some of the The photocatalytic process can be carried out by
more recent promising works include Blake (1997), simply using slurry of the fine particles of the solid
Herrmann (1999) and Bhatkhande et al. (2002). semiconductor dispersed in the liquid phase in a reactor
The photo-activated chemical reactions are character- irradiated with UV light either directly or indirectly.
ized by a free radical mechanism initiated by the The proper dispersion of the catalyst in the liquid phase
interaction of photons of a proper energy level with the can be achieved using either mechanical or magnetic
molecules of chemical species present in the solution, stirrers. Aeration, usually maintained for scavenging the
with or without the presence of the catalyst. The radicals electrons (HO2• radicals are formed in the valence
can be easily produced using UV radiation by the bonds) to prevent electronyhole charge recombination,
homogenous photochemical degradation of oxidizing also helps in achieving dispersion of the catalyst. The
compounds like hydrogen peroxide and ozone. An extent of dispersion can also be increased by sonication
alternative way to obtain free radicals is the photocatal- of the slurry at low frequency (e.g. 20 kHz) using an
ytic mechanism occurring at the surface of semiconduc- ultrasonic bath for approximately 10–15 min (Mazza-
tors (like titanium dioxide) and this indeed substantially rino et al., 1999). However, in the case of slurry
enhances the rate of generation of free radicals and reactors, the performance of the reactor might be severe-
hence the rates of degradation (Mazzarino et al., 1999). ly affected by the low irradiation efficiency due to the
A major advantage of the photocatalytic oxidation based opacity of the slurry. Also, after the oxidation treatment,
processes are the possibility to effectively use sunlight the solid catalyst needs to be separated from the liquid,
or near UV light (Bauer, 1994; Peill and Hoffmann, which is not so easy with small sizes of the catalyst
1997; Bauer and Fallmann, 1997; Guillard et al., 1999; particles (usually below 1 mm). A further problem is
Dillert et al., 1999; Fallmann et al., 1999; Herrmann et the fouling of the surface of the radiation source due to
al., 1999; Vidal et al., 1999; Yawalkar et al., 2001) for the decomposition of the catalyst particles. Thus, the
irradiation, which should result in considerable econom- application of slurry reactors for the photocatalytic
ic savings especially for large-scale operations. treatment on large-scale seems to be quite problematic
Various chalcogenides (oxides such as TiO2, ZnO, at the present time.
ZrO2, CeO2 etc. or sulfides such as CdS, ZnS etc.) have An alternative to the use of catalyst in the suspended
been used as photo-catalysts so far in different studies form is the use of supported photocatalyst. The key
reported in the literature (Davis and Huang, 1990; advantages are the possibility to obtain an active crys-
Richard and Boule, 1994; Choi and Hoffmann, 1997; talline structure and stability of the catalyst layer in the
Chen and Ray, 1998; Chen et al., 1999b; Tanaka et al., reacting media. Films obtained by wash coating using a
2000; Sakthivel et al., 2000; Andreozzi et al., 2000; suspension of commercial products with a well-known
Habibi et al., 2001a,b). The surface area and the number photocatalytic activity satisfies the first possibility, but
of active sites offered by the catalyst (thus nature of can be very sensitive to erosion by the flowing liquid.
catalyst, i.e. crystalline or amorphous is important) for Durable supported films can be obtained by different
16. 516 P.R. Gogate, A.B. Pandit / Advances in Environmental Research 8 (2004) 501–551
Fig. 3. Schematic representation of equipments based on photocatalytic oxidation.
techniques like physical and chemical vapor deposition, scale versions are also available (Matrix photocatalytic
but in this case the crystalline structure of the final Inc, Ontario Canada and Purifies Environmental Tech-
product and consequently the catalytic activity might be nologies Inc., London, Ont. Canada). It should be noted
difficult to control. Thermal treatment at 500 8C can be that any configuration can be selected, but the most
used to increase the extent of crystalline nature of the important point is to achieve uniform irradiation of the
catalyst obtained by physical or chemical vapor depo- whole active surface. Some of the equipments used for
sition. Scouring is another problem associated with films carrying out photocatalytic oxidation have been repre-
comprising immobilized powders of TiO2 (Bideau et sented in Fig. 3.
al., 1995) and reduced catalyst area to volume ratio of
the immobilized photocatalyst is likely to cause mass 3.2. Optimum operating parameters
transfer problems. Butterfield et al. (1997) have reported
a modified fabrication technique and design of the Based on the detailed and critical analysis of the
reactor in order to eliminate scouring. Here, oxide is existing literature on the photocatalytic oxidation of the
actually grown on a titanium substrate as a defect film contaminants (some of the illustrative works have been
(a film that is electronically conducting even in dark), depicted in Table 4), the important operating parameters,
which also allows application of electric field with a which affect the overall destruction efficiency of the
view of enhancement in the extent of degradation. The photocatalytic oxidation process, can be given as
batch reactor used in their work has been reported to follows:
remove 100% of E. coli and 2 log units of Cl. perfrin-
gens spores in 25 min whereas only at approximately 1. Amount and type of the catalyst: Use catalyst con-
20–30% disinfection was observed for UV light and centration only till an optimum value (Kulkarni,
UV lightqphotocatalyst. However, this exploratory 1998; Andreozzi et al., 2000; Sakthivel et al., 2000;
work needs to be tested on a large-scale and more Dijkstra et al., 2001; Gogate et al., 2002a), as using
importantly for the degradation of complex chemicals excess catalyst reduces the amount of photo-energy
before firm recommendations can be made. being transferred in the medium due to opacity
Overall, the immobilized or supported catalytic reac- offered by the catalyst particles. It should also be
tors offer many advantages; most important being the noted that the optimum value will strongly be
supported catalyst is not allowed to mix with the fluid dependent on the type and concentration of the
avoiding the requirement of ultrafine particle separation. pollutant, as well as the rate of generation of free
Various devices have been developed such as TiO2 radicals (decided by the operating conditions of the
coated tubular photoreactor, annular and spiral photo- reactor) and laboratory scale experiments are required
reactors, falling-film photoreactors and two commercial to decide the optimum value unless data are available
17. Table 4
Typical findings observed in the representative works related to photocatalytic destruction of effluents
Sr. no. Reference Type of equipment and experimental details Important findings of the work
1 Beltran et al. (1997) Annular glass photoreactor with capacity of Distillery wastes are completely refractory toward
850 ml irradiated by 15 W low-pressure UV irradiation whereas in presence of hydrogen
mercury vapor UV lamp. Pollutant studied: peroxide, degradation is observed only at diluted
Distillery wastewaters (COD range of 750– conditions (38% reduction in 2 h at COD of
P.R. Gogate, A.B. Pandit / Advances in Environmental Research 8 (2004) 501–551
3000) and Tomato wastewaters (COD range 850 mgyl whereas nil for COD of 3000 mgyl). For
of 250–960) tomato wastewaters, higher initial COD gives
higher degradation, but the rate decreases with
progressing time due to the formation of UV radiation
absorbing intermediates. The rates of degradation
are much lower with only 18% reduction in 2 h
2 Ray and Beenackers (1997) Novel swirl flow reactor operating in Mass transfer coefficient increases with increase in
continuous mode consisting of two glass plates the flowrate (a Re0.62). If catalyst is kept at the
placed between soft padding housed within SS bottom plate, significant reduction in the rates of
and aluminium casings. Catalyst can be degradation is observed due to absorption of the UV
deposited on either plates and effluent is light by the liquid. 908 angle of incidence gives
introduced tangentially between two plates, maximum rate of degradation. Increase in
which creates a swirl flow minimizing the mass light intensity increases the degradation significantly
transfer resistance. Phillips high-pressure till 50 Wym2 beyond which the increase is marginal.
mercury lamp with power of 125 W is used Optimum catalyst concentration is found to be
with intensity of 213 Wym2. Degussa P-25, and 0.003 kgym2. Hombikat UV 100 gives more extent
Hombikat UV 100 immobilised on a UV of degradation as compared to Degussa P-25
transparent material is used as photocatalyst. possibly due to the lower particle size
Pollutant studied: SBB dye
3 Kulkarni (1998) Kettle type reactor with capacity of 500 ml The degradation process is almost complete within
stirred continuously with magnetic stirrer. A two hours of reaction time and followed first order
parabolic reflector was used to concentrate kinetics. No appreciable reaction takes place
the sunlight. Degussa P-25 TiO2 with BET without aeration. Increase in the radiation intensity
surface area of 50 m2yg was used as the increases the extent of degradation almost linearly.
photocatalyst. Pollutant studied: Distillery Optimum catalyst concentration was found to be
waste with TOC of 3.52% 500 ppm
4 Chen and Ray (1998) Swirl flow reactor irradiated with 125 W high- Reaction mechanism has been proposed. No
pressure mercury vapor lamp. 0.2 wt.% degradation for individual TiO2 or UV light but
powder photocatalyst TiO2 of Degussa P-25 illuminated TiO2 gives significant rates (Complete
or Hombikat UV-100 grade was suspended. destruction within 100 min). Optimum TiO2 loading is
Pollutant studied: 4-nitrophenol found to be 3 gmyl. Rate constant increases with
decrease in the initial concentration of the pollutant.
The exponent over incident intensity is found to be
0.84 (between 1 for catalyst controlling and 0.5 for
mass transfer controlling) indicating that catalyst and
mass transfer resistance are both contributing. Rate
517
constant increases with an increase in the temperature
18. 518
Table 4 (Continued)
Sr. no. Reference Type of equipment and experimental details Important findings of the work
and also with oxygen partial pressure (however, 70%
of the maximum rate is observed at 0.2 atm pressure
indicating that air may be used in commercial
applications). Maximum rate is observed at pH equal
to the pZc point of TiO2 catalyst. In the presence of
P.R. Gogate, A.B. Pandit / Advances in Environmental Research 8 (2004) 501–551
chloride ions, substantial decrease in rates is observed
due to competitive adsorption on TiO2 surface.
Hombikat UV-100 is more active as compared to
Degussa P-25
5 Mazzarino et al. (1999) Two different reactor configurations with Biphasic flow (simultaneous flow of air and effluent)
tubular configuration having an axial cylindrical gives more degradation efficiency as compared to
lamp and an annular free space for movement monophasic flow (effluent saturated with air).
of liquid. One is operated in batch recycle Increased turbulence due to gas bubble decreases
mode (catalyst in suspended form) with the mass transfer resistance thus indicating that
capacity of 1000 ml and power input of 15 W transfer of reactants towards the catalyst surface is
whereas continuous single pass reactor the rate-controlling step. Also, oxygen prevents
(supported photocatalyst) is with capacity of recombination of electron-vacancy pairs. First order
2721 ml and power input of 40 W. kinetics has been observed. Decrease in TOC is
Photocatalyst is Degussa P-25 titania. Pollutant significantly slower than the removal of acid. Presence
studied: Glycolic acid of hydrogen peroxide increases the rate of
degradation by approximately 2 times (for
photochemical process but marginal effect in the
presence of catalyst). For slurry reactors, optimum
catalyst concentration is observed to be 100 ppm.
For monophasic flow, slurry reactor is slightly efficient
but for the biphasic flow supported bed continuous
reactor gives approximately 3 times faster rate as
compared to the slurry reactor
6 Xu et al. (1999) Pyrex glass container of capacity 850 ml with Significant adsorption of methylene blue on TiO2
annular irradiation with a mercury lamp (saturation adsorbability in the range of 0.36–3.6
(300 W). Temperature maintained at 25 8C mgyg of TiO2) and it increases with a decrease in the
using cooling water circulation and initial pH of size of TiO2 particle. Amorphous grade TiO2 exhibits
6. TiO2 with catalyst loading of 0.588 mgyml very poor catalytic activity. Presence of catalyst
with different grades viz anatase, amorphous enhances MB degradation and it further increases
and particle size in the range 12 nm to 49 with a decrease in the size of catalyst particle.
mm. Pollutant studied: Methylene blue (MB) Dramatic increase in the rate is observed below
particle size of 30 nm. Correlation for kinetic rate
constant and half life in terms of the diameter of
particle has been given. TiO2 suspended
photocatalytic reaction is concluded to be more
appropriate as compared to fixed bed type due to
avoidance of preparation of ultrafine particles; still the