The document provides an overview of biodisc characteristics for wastewater treatment and discusses their design and operation. Biodiscs consist of rotating plastic discs partially submerged in a tank, with microorganisms adhered to the surface that degrade organic matter in wastewater. Well-operated biodiscs can remove 80-95% of organic matter and nitrify wastewater. Design considerations include disc material, configuration, and biofilm thickness. Biodiscs have advantages like flexibility, low energy use, and the ability to treat variable flows.
Thermax offers integrated water management solutions including sewage treatment. Their fluidized aerobic biofilm (FAB) reactor uses floating media to support biomass growth, treating sewage in an attached film with advantages over conventional activated sludge processes. The modular FAB system can achieve over 90% reductions in both BOD and COD using two reactors in series with countercurrent air-wastewater flow.
This SlideShare was authored by Dr. Ananth Seshadri Kodavasal who has more than 30 years of experience as an environmental Engineer and is a looked upon as a foremost authority on Sewage Treatment Plants.
It was presented during Water Workshop conducted by ApartmentADDA on 25-Feb-2012. It explains the below topics
• Wastewater Pollutants/Impact
• Physical, Chemical, Biological Unit Operations
• Types & Effects of Pollution
• Biological Treatment Variants
• Pros and Cons
At last the SlideShare details on the Important Acts and rules related to Environmental Protection.
Check the link below for details
http://apartmentadda.com/blog/water-workshop-for-apartments-report/
This is a power point presentation on design of a 30 MLD sewage treatment plant. It includes the different characteristics of waste water,various treatment units, design results and a layout of sewage treatment plant.
Visit my slide share channel for downloading report of this project.
Technical calculations for the biological treatment plantAlex Tagbo
This document discusses the design and operation of a decentralized wastewater treatment plant in Chennai, India that uses biological treatment processes. The plant serves 55,000 people and uses principles of carbon elimination, nitrification, and denitrification. It follows guidelines from ATV 131, the German technical standard for wastewater treatment plant design. The document outlines the treatment process, design considerations, and compares German and Indian wastewater treatment standards. It also analyzes how treatment plant size and volume requirements vary with influent temperature and population size.
This SlideShare is about Sewage Treatment Plants in Residential Complexes presented by Dr.Ananth S Kodavasal, Ecotech engineering in "Estate Manager Workshop-II" conducted by ApartmentADDA on 18th Nov 2010 in Bangalore.
It explains the below topics
• Wastewater Pollutants/Impact
• Physical, Chemical, Biological Unit Operations
• Types & Effects of Pollution
• Biological Treatment Variants
• Pros and Cons
At last the SlideShare details on the Important Acts and rules related to Environmental Protection.
Check the link below for details
http://apartmentadda.com/blog/water-workshop-for-apartments-report/
The difference between sbr, mbr and mbbr-sewage treatment plantsCleantechwater_19
The document discusses and compares three different types of sewage treatment plants: SBR, MBR, and MBBR. It defines each type of plant, noting that SBR uses a sequencing batch reactor process, MBR uses a membrane bioreactor process, and MBBR uses a moving bed biofilm reactor process. The document also mentions that MBR and MBBR both use membrane and biological processes. It states that SBR plants have a smaller footprint and are easier to operate than MBR or MBBR plants, which have less turbidity and produce less water sludge.
Sequential batch reactors (SBR) are a type of wastewater treatment process that treats wastewater in batches through five stages: fill, react, settle, decant, and idle. During the fill stage, wastewater enters the tank and is mixed. In the react stage, oxygen is bubbled in to reduce organic matter through microbial activity. Solids then settle in the settle stage before the treated water is decanted in the decant stage. The tank then idles until the next cycle starts again with filling. SBR is effective at reducing biochemical oxygen demand and ammonia through this sequential batch process.
The document discusses various technologies for sewage treatment including activated sludge process (ASP), moving bed bioreactor (MBBR), sequential batch reactor (SBR), membrane bioreactor (MBR), upflow anaerobic sludge blanket (UASB) reactor, and trickling filter (TF). It provides diagrams of process flow and compares the technologies based on parameters like space requirement, capital cost, power consumption, and treated effluent quality. The best technology depends on the objective of the sewage treatment plant whether it is reducing capital cost, space, or operation cost while ensuring good quality treated water.
Thermax offers integrated water management solutions including sewage treatment. Their fluidized aerobic biofilm (FAB) reactor uses floating media to support biomass growth, treating sewage in an attached film with advantages over conventional activated sludge processes. The modular FAB system can achieve over 90% reductions in both BOD and COD using two reactors in series with countercurrent air-wastewater flow.
This SlideShare was authored by Dr. Ananth Seshadri Kodavasal who has more than 30 years of experience as an environmental Engineer and is a looked upon as a foremost authority on Sewage Treatment Plants.
It was presented during Water Workshop conducted by ApartmentADDA on 25-Feb-2012. It explains the below topics
• Wastewater Pollutants/Impact
• Physical, Chemical, Biological Unit Operations
• Types & Effects of Pollution
• Biological Treatment Variants
• Pros and Cons
At last the SlideShare details on the Important Acts and rules related to Environmental Protection.
Check the link below for details
http://apartmentadda.com/blog/water-workshop-for-apartments-report/
This is a power point presentation on design of a 30 MLD sewage treatment plant. It includes the different characteristics of waste water,various treatment units, design results and a layout of sewage treatment plant.
Visit my slide share channel for downloading report of this project.
Technical calculations for the biological treatment plantAlex Tagbo
This document discusses the design and operation of a decentralized wastewater treatment plant in Chennai, India that uses biological treatment processes. The plant serves 55,000 people and uses principles of carbon elimination, nitrification, and denitrification. It follows guidelines from ATV 131, the German technical standard for wastewater treatment plant design. The document outlines the treatment process, design considerations, and compares German and Indian wastewater treatment standards. It also analyzes how treatment plant size and volume requirements vary with influent temperature and population size.
This SlideShare is about Sewage Treatment Plants in Residential Complexes presented by Dr.Ananth S Kodavasal, Ecotech engineering in "Estate Manager Workshop-II" conducted by ApartmentADDA on 18th Nov 2010 in Bangalore.
It explains the below topics
• Wastewater Pollutants/Impact
• Physical, Chemical, Biological Unit Operations
• Types & Effects of Pollution
• Biological Treatment Variants
• Pros and Cons
At last the SlideShare details on the Important Acts and rules related to Environmental Protection.
Check the link below for details
http://apartmentadda.com/blog/water-workshop-for-apartments-report/
The difference between sbr, mbr and mbbr-sewage treatment plantsCleantechwater_19
The document discusses and compares three different types of sewage treatment plants: SBR, MBR, and MBBR. It defines each type of plant, noting that SBR uses a sequencing batch reactor process, MBR uses a membrane bioreactor process, and MBBR uses a moving bed biofilm reactor process. The document also mentions that MBR and MBBR both use membrane and biological processes. It states that SBR plants have a smaller footprint and are easier to operate than MBR or MBBR plants, which have less turbidity and produce less water sludge.
Sequential batch reactors (SBR) are a type of wastewater treatment process that treats wastewater in batches through five stages: fill, react, settle, decant, and idle. During the fill stage, wastewater enters the tank and is mixed. In the react stage, oxygen is bubbled in to reduce organic matter through microbial activity. Solids then settle in the settle stage before the treated water is decanted in the decant stage. The tank then idles until the next cycle starts again with filling. SBR is effective at reducing biochemical oxygen demand and ammonia through this sequential batch process.
The document discusses various technologies for sewage treatment including activated sludge process (ASP), moving bed bioreactor (MBBR), sequential batch reactor (SBR), membrane bioreactor (MBR), upflow anaerobic sludge blanket (UASB) reactor, and trickling filter (TF). It provides diagrams of process flow and compares the technologies based on parameters like space requirement, capital cost, power consumption, and treated effluent quality. The best technology depends on the objective of the sewage treatment plant whether it is reducing capital cost, space, or operation cost while ensuring good quality treated water.
The document provides an overview of moving bed biofilm reactors (MBBR) for wastewater treatment. It discusses the history and introduction of MBBR technology, key designing parameters such as media size and surface area, and operating parameters like retention times and loading rates. An example design for a 600 cubic meter per day MBBR wastewater treatment plant is presented, outlining the treatment process flow including aeration, settling, and disinfection. Finally, the document reviews a paper comparing the treatment performance of MBBR versus conventional activated sludge systems.
The Texas A&M Wastewater Treatment Plant uses conventional activated sludge treatment processes to treat wastewater from campus buildings. It is designed to treat up to 11,700 pounds of biochemical oxygen demand per day from a population equivalent of 69,900 people. The plant utilizes primary and secondary clarification, aeration, ultraviolet disinfection, and land application of biosolids to treat wastewater and remove contaminants before water is recycled or biosolids are used as fertilizer. Laboratory testing ensures the plant meets regulatory requirements for effluent water quality.
Design of 210 Mld Sewage Treatment PlantARUN KUMAR
This document provides details on the design of a 210 million liter per day sewage treatment plant. It discusses the need for the plant to treat sewage and prevent pollution. It then describes the three main stages of sewage treatment - primary, secondary, and tertiary treatment. Primary treatment involves removing solids and debris. Secondary treatment uses microorganisms to break down dissolved organic matter. Tertiary treatment further polishes the water with methods like filtration and chlorination before discharge.
This document describes a pilot project to minimize the impact of phosphorus and other nutrients entering lake watersheds from rural residential septic systems. It proposes linking gray water reuse systems and aerobic treatment unit systems to existing septic systems to achieve more effective treatment. The gray water reuse system would reduce the volume of water entering the septic system through filtration, disinfection, and gray water reuse. The aerobic treatment unit system would enhance treatment in the septic tank through aeration and additives to help remove total phosphorus before effluent reaches the drain field. Three target property types are identified for the pilot projects.
This document provides an overview of water issues and sewage treatment processes. It discusses the global water crisis, reasons for water scarcity in India like increasing demand and decreasing supply. It then describes the various unit processes involved in sewage treatment like bar screens, neutralization, activated sludge process using aeration tanks and secondary clarifiers, and tertiary treatment using processes like filtration and UV disinfection. The importance of proper operation and maintenance of sewage treatment plants is also emphasized.
Redox Environment B.V. at Winterswijk, The netherlands, has developped a total process for waterrecycling for municipal and office buildings, laoding stations, small municipalities,etc., etc,.
Deals with UASB reactors for the primary treatment of sewage, stabilization of sludge and removal of BOD. Various components of a UASB reactor are described and design details are included. Modifications to UASB such as UASB ponds, Anaerobic baffle reactors, migrating blanket reactors are also described here.
The document discusses sequencing batch reactors (SBRs) for wastewater treatment. SBRs perform the stages of treatment - equalization, biological treatment, and clarification - sequentially in a single tank. Key advantages are that SBRs require less space than traditional systems using separate tanks for each stage, and can achieve high removal rates of various pollutants. The SBR process involves repeated fill, react, settle, decant, and idle phases in the single tank reactor.
Biological treatment processes use microorganisms like bacteria and fungi to remove organic matter from wastewater. The most common type is activated sludge, which uses air bubbles in one basin to provide oxygen and mix wastewater and microbes, then a settling basin to remove microbial solids. Trickling filters and biological contactors grow microbial slime on solid surfaces that contact wastewater. Imhoff tanks separate wastewater into an upper settling chamber and lower anaerobic digestion chamber. Anaerobic lagoons treat manure wastewater through microbial breakdown that produces methane and other gases.
This document discusses the design of a sewage treatment plant for the town of Ulavapadu, India to address the problems of increasing pollution and diseases due to rising population. The author analyzes the current sewage parameters and designs the treatment plant with primary, secondary and tertiary units including screens, grit chambers, sedimentation tanks, aeration tanks and sludge digestion. The plant is designed to treat the sewage of the projected future population of 26,710 people over the next 40 years.
This document discusses the reuse of greywater in buildings. It provides an overview of greywater quality guidelines, treatment technologies, and case studies of greywater reuse systems. Some key points include:
- Greywater accounts for 50-80% of household wastewater and can be treated and reused for purposes like toilet flushing and irrigation.
- Treatment typically involves physical separation followed by disinfection. Promising technologies include membrane bioreactors and constructed wetlands.
- Case studies from Norway, Italy, Germany demonstrate greywater systems that consistently achieve high removal of contaminants to meet reuse standards.
The document summarizes the evolution of sewage treatment technology in Malaysia from primitive to modern systems. It describes early methods like pour flush concepts and individual septic tanks used from 1950-1960s. Imhoff tanks were introduced from 1970-1990s providing partial treatment. Modern water treatment plants now use tertiary treatment with mechanical systems and combined sewers to fully treat sewage since 2000s. Factors like health issues, river pollution and environmental concerns drove changes to sewage treatment in Malaysia over time. The document also differentiates between combined and separated sewer piping systems.
Construction,operation and maintenance of trickling filter2Shivamsanoo
The document discusses the construction, operation, and maintenance of trickling filters. It describes the technology, materials, and analysis used in construction. It explains the biology of bacteria and microorganisms involved in operation. Maintenance requires periodic washing to prevent clogging and monitoring by a skilled operator. Designs can include one-stage or two-stage filters. Advantages include high nitrification and good dependability, while disadvantages include head loss and high costs.
This document provides an overview of wastewater treatment and the use of upflow anaerobic sludge blanket (UASB) technology. It discusses the characteristics of wastewater and the need for treatment. The objectives of the project are to treat 130 million liters per day of domestic wastewater using UASB. Historical developments of UASB technology are also summarized, including early pilot plants in India in the 1980s-1990s that demonstrated it was effective for domestic wastewater treatment with low energy use and costs.
This document summarizes a case study on sewage treatment and reuse. It discusses the objectives of conserving water and reusing treated water effectively. It describes the various treatment processes used, including primary treatment involving screening and settling, secondary treatment using UASB reactors and lagoons, and disinfection. The case study then analyzes a specific research study on treating sewage in India using activated sludge, chlorination, and dual media filtration. It provides results showing reductions in contaminants like BOD, COD, and coliform during treatment. The conclusion states that dual media filtration helps further treat sewage water to allow reuse rather than discharge, preserving natural resources and the environment.
The document summarizes the sewage treatment process at Amrita University using Effective Microbes (EM) technology. Sewage water from hostels and residences totaling 7 lakh liters per day is processed through three treatment plants with no chemical use. The water is screened, equalized, aerated by bacteria, clarified, further purified, and then recycled to irrigate farms and gardens. The treated effluent water is free of heavy metals and pathogens and the process is more cost effective than traditional activated sludge methods. The resulting manure is also used as fertilizer on the university campus.
Reed bed technology uses shallow beds planted with reeds to treat wastewater through natural processes. There are two main types of reed beds - horizontal flow beds where wastewater flows horizontally through the reed root zone, and vertical flow beds where wastewater is delivered to the top of the bed in batches and drains vertically. Reed beds rely on the reeds and microbial activity in the bed's gravel layers to break down pollutants in wastewater over a detention period of 5-7 days. Factors like temperature, pollutant concentration, and oxygen levels influence the purification process. Reed beds provide a low-cost, sustainable option for treating various types of wastewater with minimal maintenance requirements.
Primary and secondary wastewater treatment..snehalmenon92
This document provides an overview of primary and secondary wastewater treatment processes. It begins by defining wastewater treatment as applying technology to improve water quality. Primary treatment involves removing coarse solids and grit, while secondary treatment uses biological processes like activated sludge to further break down organic matter. The document then describes various primary and secondary treatment units and processes in detail, such as grit chambers, primary clarifiers, trickling filters, and biological nutrient removal. It concludes by discussing tertiary/advanced treatment options for removing additional contaminants.
1) A soak pit is an underground chamber that allows pre-treated wastewater from a septic tank to slowly soak into the ground.
2) It is designed with a layer of sand and gravel at the bottom to disperse the flow and is typically 1.5-4m deep with a casing of coarse sand.
3) The wastewater percolates through the soil where small particles are filtered out and organics are digested, though eventual clogging of the pit is inevitable and requires cleaning.
This document provides an overview of biological treatments of water. It begins with an abstract describing biological treatment systems that use microorganisms to break down organic materials. It then discusses water treatment processes generally before focusing on biological methods. The key biological methods described are aerobic treatment which uses oxygen and aerobic microorganisms, and anaerobic treatment which does not use oxygen and relies on anaerobic microorganisms. Specific biological treatment technologies summarized include conventional activated sludge processes, cyclic activated sludge systems, trickling filters, and phytoremediation. The document emphasizes that both aerobic and anaerobic biological methods are often used together to effectively treat wastewater.
Low Cost Anaerobic Treatment of Municipal Solid Waste Leachateiosrjce
IOSR Journal of Environmental Science, Toxicology and Food Technology (IOSR-JESTFT) multidisciplinary peer-reviewed Journal with reputable academics and experts as board member. IOSR-JESTFT is designed for the prompt publication of peer-reviewed articles in all areas of subject. The journal articles will be accessed freely online
The document provides an overview of moving bed biofilm reactors (MBBR) for wastewater treatment. It discusses the history and introduction of MBBR technology, key designing parameters such as media size and surface area, and operating parameters like retention times and loading rates. An example design for a 600 cubic meter per day MBBR wastewater treatment plant is presented, outlining the treatment process flow including aeration, settling, and disinfection. Finally, the document reviews a paper comparing the treatment performance of MBBR versus conventional activated sludge systems.
The Texas A&M Wastewater Treatment Plant uses conventional activated sludge treatment processes to treat wastewater from campus buildings. It is designed to treat up to 11,700 pounds of biochemical oxygen demand per day from a population equivalent of 69,900 people. The plant utilizes primary and secondary clarification, aeration, ultraviolet disinfection, and land application of biosolids to treat wastewater and remove contaminants before water is recycled or biosolids are used as fertilizer. Laboratory testing ensures the plant meets regulatory requirements for effluent water quality.
Design of 210 Mld Sewage Treatment PlantARUN KUMAR
This document provides details on the design of a 210 million liter per day sewage treatment plant. It discusses the need for the plant to treat sewage and prevent pollution. It then describes the three main stages of sewage treatment - primary, secondary, and tertiary treatment. Primary treatment involves removing solids and debris. Secondary treatment uses microorganisms to break down dissolved organic matter. Tertiary treatment further polishes the water with methods like filtration and chlorination before discharge.
This document describes a pilot project to minimize the impact of phosphorus and other nutrients entering lake watersheds from rural residential septic systems. It proposes linking gray water reuse systems and aerobic treatment unit systems to existing septic systems to achieve more effective treatment. The gray water reuse system would reduce the volume of water entering the septic system through filtration, disinfection, and gray water reuse. The aerobic treatment unit system would enhance treatment in the septic tank through aeration and additives to help remove total phosphorus before effluent reaches the drain field. Three target property types are identified for the pilot projects.
This document provides an overview of water issues and sewage treatment processes. It discusses the global water crisis, reasons for water scarcity in India like increasing demand and decreasing supply. It then describes the various unit processes involved in sewage treatment like bar screens, neutralization, activated sludge process using aeration tanks and secondary clarifiers, and tertiary treatment using processes like filtration and UV disinfection. The importance of proper operation and maintenance of sewage treatment plants is also emphasized.
Redox Environment B.V. at Winterswijk, The netherlands, has developped a total process for waterrecycling for municipal and office buildings, laoding stations, small municipalities,etc., etc,.
Deals with UASB reactors for the primary treatment of sewage, stabilization of sludge and removal of BOD. Various components of a UASB reactor are described and design details are included. Modifications to UASB such as UASB ponds, Anaerobic baffle reactors, migrating blanket reactors are also described here.
The document discusses sequencing batch reactors (SBRs) for wastewater treatment. SBRs perform the stages of treatment - equalization, biological treatment, and clarification - sequentially in a single tank. Key advantages are that SBRs require less space than traditional systems using separate tanks for each stage, and can achieve high removal rates of various pollutants. The SBR process involves repeated fill, react, settle, decant, and idle phases in the single tank reactor.
Biological treatment processes use microorganisms like bacteria and fungi to remove organic matter from wastewater. The most common type is activated sludge, which uses air bubbles in one basin to provide oxygen and mix wastewater and microbes, then a settling basin to remove microbial solids. Trickling filters and biological contactors grow microbial slime on solid surfaces that contact wastewater. Imhoff tanks separate wastewater into an upper settling chamber and lower anaerobic digestion chamber. Anaerobic lagoons treat manure wastewater through microbial breakdown that produces methane and other gases.
This document discusses the design of a sewage treatment plant for the town of Ulavapadu, India to address the problems of increasing pollution and diseases due to rising population. The author analyzes the current sewage parameters and designs the treatment plant with primary, secondary and tertiary units including screens, grit chambers, sedimentation tanks, aeration tanks and sludge digestion. The plant is designed to treat the sewage of the projected future population of 26,710 people over the next 40 years.
This document discusses the reuse of greywater in buildings. It provides an overview of greywater quality guidelines, treatment technologies, and case studies of greywater reuse systems. Some key points include:
- Greywater accounts for 50-80% of household wastewater and can be treated and reused for purposes like toilet flushing and irrigation.
- Treatment typically involves physical separation followed by disinfection. Promising technologies include membrane bioreactors and constructed wetlands.
- Case studies from Norway, Italy, Germany demonstrate greywater systems that consistently achieve high removal of contaminants to meet reuse standards.
The document summarizes the evolution of sewage treatment technology in Malaysia from primitive to modern systems. It describes early methods like pour flush concepts and individual septic tanks used from 1950-1960s. Imhoff tanks were introduced from 1970-1990s providing partial treatment. Modern water treatment plants now use tertiary treatment with mechanical systems and combined sewers to fully treat sewage since 2000s. Factors like health issues, river pollution and environmental concerns drove changes to sewage treatment in Malaysia over time. The document also differentiates between combined and separated sewer piping systems.
Construction,operation and maintenance of trickling filter2Shivamsanoo
The document discusses the construction, operation, and maintenance of trickling filters. It describes the technology, materials, and analysis used in construction. It explains the biology of bacteria and microorganisms involved in operation. Maintenance requires periodic washing to prevent clogging and monitoring by a skilled operator. Designs can include one-stage or two-stage filters. Advantages include high nitrification and good dependability, while disadvantages include head loss and high costs.
This document provides an overview of wastewater treatment and the use of upflow anaerobic sludge blanket (UASB) technology. It discusses the characteristics of wastewater and the need for treatment. The objectives of the project are to treat 130 million liters per day of domestic wastewater using UASB. Historical developments of UASB technology are also summarized, including early pilot plants in India in the 1980s-1990s that demonstrated it was effective for domestic wastewater treatment with low energy use and costs.
This document summarizes a case study on sewage treatment and reuse. It discusses the objectives of conserving water and reusing treated water effectively. It describes the various treatment processes used, including primary treatment involving screening and settling, secondary treatment using UASB reactors and lagoons, and disinfection. The case study then analyzes a specific research study on treating sewage in India using activated sludge, chlorination, and dual media filtration. It provides results showing reductions in contaminants like BOD, COD, and coliform during treatment. The conclusion states that dual media filtration helps further treat sewage water to allow reuse rather than discharge, preserving natural resources and the environment.
The document summarizes the sewage treatment process at Amrita University using Effective Microbes (EM) technology. Sewage water from hostels and residences totaling 7 lakh liters per day is processed through three treatment plants with no chemical use. The water is screened, equalized, aerated by bacteria, clarified, further purified, and then recycled to irrigate farms and gardens. The treated effluent water is free of heavy metals and pathogens and the process is more cost effective than traditional activated sludge methods. The resulting manure is also used as fertilizer on the university campus.
Reed bed technology uses shallow beds planted with reeds to treat wastewater through natural processes. There are two main types of reed beds - horizontal flow beds where wastewater flows horizontally through the reed root zone, and vertical flow beds where wastewater is delivered to the top of the bed in batches and drains vertically. Reed beds rely on the reeds and microbial activity in the bed's gravel layers to break down pollutants in wastewater over a detention period of 5-7 days. Factors like temperature, pollutant concentration, and oxygen levels influence the purification process. Reed beds provide a low-cost, sustainable option for treating various types of wastewater with minimal maintenance requirements.
Primary and secondary wastewater treatment..snehalmenon92
This document provides an overview of primary and secondary wastewater treatment processes. It begins by defining wastewater treatment as applying technology to improve water quality. Primary treatment involves removing coarse solids and grit, while secondary treatment uses biological processes like activated sludge to further break down organic matter. The document then describes various primary and secondary treatment units and processes in detail, such as grit chambers, primary clarifiers, trickling filters, and biological nutrient removal. It concludes by discussing tertiary/advanced treatment options for removing additional contaminants.
1) A soak pit is an underground chamber that allows pre-treated wastewater from a septic tank to slowly soak into the ground.
2) It is designed with a layer of sand and gravel at the bottom to disperse the flow and is typically 1.5-4m deep with a casing of coarse sand.
3) The wastewater percolates through the soil where small particles are filtered out and organics are digested, though eventual clogging of the pit is inevitable and requires cleaning.
This document provides an overview of biological treatments of water. It begins with an abstract describing biological treatment systems that use microorganisms to break down organic materials. It then discusses water treatment processes generally before focusing on biological methods. The key biological methods described are aerobic treatment which uses oxygen and aerobic microorganisms, and anaerobic treatment which does not use oxygen and relies on anaerobic microorganisms. Specific biological treatment technologies summarized include conventional activated sludge processes, cyclic activated sludge systems, trickling filters, and phytoremediation. The document emphasizes that both aerobic and anaerobic biological methods are often used together to effectively treat wastewater.
Low Cost Anaerobic Treatment of Municipal Solid Waste Leachateiosrjce
IOSR Journal of Environmental Science, Toxicology and Food Technology (IOSR-JESTFT) multidisciplinary peer-reviewed Journal with reputable academics and experts as board member. IOSR-JESTFT is designed for the prompt publication of peer-reviewed articles in all areas of subject. The journal articles will be accessed freely online
This document reviews the applicability and design of sequencing batch reactors (SBRs) for wastewater treatment. It discusses how SBRs can be modified to treat different types of wastewater more efficiently than conventional activated sludge processes. The review finds that SBRs can effectively treat municipal, industrial, synthetic, and piggery wastewaters through various cycle phases and operating conditions. SBRs have been shown to achieve high removal rates of pollutants like biochemical oxygen demand, total suspended solids, nutrients, and heavy metals from different wastewaters. The document examines several lab-scale and pilot-scale studies that demonstrate SBRs' treatment performance and ability to be optimized for different wastewater compositions.
Review of research on bio reactors used in wastewater ijsit 2.4.6IJSIT Editor
This document reviews various types of bioreactors used in wastewater treatment for biohydrogen production, including batch, continuous stirred tank, plug flow, biofilm, suspended growth, upflow anaerobic sludge blanket, anaerobic baffled, upflow packed bed, fluidized bed, sequencing batch, and membrane separation reactors. It discusses the operating principles and advantages/limitations of these different reactor configurations. The review concludes that significant progress has been made in developing advanced high-rate anaerobic reactors to improve wastewater treatment efficiency and biogas production for hydrogen fuel applications.
Factors affecting biogas production during anaerobic decomposition of brewery...Alexander Decker
This document summarizes a study that analyzed factors affecting biogas and carbon dioxide production during anaerobic decomposition of brewery wastewater in a fluidized bed digester. The study monitored gas production at different microbial concentrations, hydraulic retention times, and volatile fatty acid to alkalinity ratios. Maximum gas volumes were recorded at 8 hours hydraulic retention time, corresponding to favorable operating conditions and good system stability. The biogas produced was rich in methane and could potentially be integrated into the brewery's energy mix to improve process economics.
BIOTECHNOLOGICAL APPROACHES TOWARDS WATER WASTE MANAGEMENT saadmughal1271
This document discusses various biotechnological approaches for wastewater treatment, including engineered biosorbents for heavy metal removal, displaying metal binding peptides on microorganisms, and designing strains for enhanced biodegradation. It describes common wastewater treatment processes like the trickling filter, activated sludge process, and anaerobic digestion. Finally, it discusses using these biotechnological methods to treat wastewater from textile and desiccated coconut industries.
JBEI Research Highlights Slides - October 2022SaraHarmon4
This document summarizes three research articles from the Office of Biological and Environmental Research.
The first article describes an approach to engineer permeability in microfluidic compartments, enabling sustained multi-cycle protein production in a cell-free system and enhanced environmental fitness for bacteria-enclosing compartments.
The second article examines carbon metabolism in soil by tracking stable isotope enrichment of metabolites from various carbon sources, finding profiles varied more by source than time and corresponded to differences in active microbial populations.
The third article compares performance of parallel microbiomes cultivated on sorghum, finding actinobacteria differentiated outcomes and network reconstructions revealed enzyme-linked processing stages.
This patent discloses a waste treatment system that uses primary treatment, aeration of the waste in an equalization tank, and application of the waste to a rotating disk biological reactor. The rotating disk reactor contains a plurality of disks made of thin wedge-shaped elements that can be tightly packed for shipping but spaced apart when assembled, allowing biological slime to form on the surfaces. This arrangement improves on prior rotating disk reactors by making the disks easier and cheaper to transport and assemble.
An Overview of Membrane Bioreactors for Anaerobic Treatment of WastewatersAM Publications
Application of Anaerobic Membrane Bioreactor (AnMBR) for wastewater treatment could be an attractive alternative to
recover energy in terms of biogas. In recent years, researchers have shown that AnMBRs can be used to produce methane from
synthetic wastewater. Studies were conducted in the laboratory scale anaerobic Membrane Bioreactor for treatment of synthetic
wastewater at different organic loading rates, under thermophillic and mesophilic conditions and ranging membrane flux. These
AnMBRs performed well for COD and BOD removal from the wastewater, demonstrating the effectiveness of this device for
wastewater treatment with COD and BOD removal efficiency above 90%. Results show that the application of anaerobic
membrane bioreactors is an efficient way to retain specific bacteria that can be a key for the treatment of wastewaters under
extreme conditions. The latter would enable their application to a wide range of industrial processes with the purpose of water
recycling. The challenge for future research is finding the optimum operational conditions to control the cake layer formation,
enhancing membrane performance and reducing the membrane area requirements. This will increase the economic feasibility of
AnMBRs, enabling its full scale application. The performance of the AnMBRs as reported in literature with different substrates,
membrane fouling issues and different membrane rector configurations are presented in this paper.
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.
IRJET- Effect of Biofilm Filling Rates, Various Cycles Duration and Organic L...IRJET Journal
This document summarizes a study that investigated the effect of biofilm filling rates, cycle durations, and organic loading rates on organic and nutrient removal in a sequencing batch biofilm reactor (SBBR). The study was conducted in three phases:
1) The first phase tested biofilm filling rates of 0%, 50%, and 25% and found that higher filling rates improved removal of BOD, COD, nitrogen, and phosphorus.
2) The second phase tested cycle durations of 8-2, 7-3, and 6-4 hours for aeration and settling, finding slightly higher removal rates for longer durations.
3) The third phase tested organic loading rates of 0.84 and 1.44 kg COD/
This document summarizes a study evaluating amendments to improve the effectiveness of biowalls used for groundwater remediation at sites with high sulfate concentrations. The biowall at Altus Air Force Base in Oklahoma was experiencing reduced performance due to sulfide toxicity. Laboratory tests evaluated different iron sources that could be combined with emulsified vegetable oil amendments to precipitate sulfide and buffer toxicity. Field tests at a pilot biowall compared vegetable oil alone to vegetable oil combined with ferrous lactate and nano hematite. Preliminary results are being analyzed to assess enhancement of reductive dechlorination from the iron additives and determine if they should be included in biowall rejuvenation at high-sulfate sites.
This document reviews the development and use of the anaerobic baffled reactor (ABR) for wastewater treatment. Some key points:
- The ABR was developed in the 1980s as an alternative to systems like the upflow anaerobic sludge blanket (UASB) reactor. It provides better resilience to shocks and longer biomass retention times.
- Various modifications to the original ABR design have been made to improve performance, such as narrowing downflow chambers, adding settling zones, and using different packing materials. These modifications aim to enhance solids retention and the reactor's ability to treat more difficult wastewaters.
- A key advantage of the ABR is its
Biological and Advanced Water Treatment.pptxYalelet Abera
Micro-organisms play an essential role in the biological treatment of wastewater by converting organic waste into more stable substances. There are three main types of biological wastewater treatment processes - aerobic, anaerobic, and anoxic. Two common biological wastewater treatment methods are trickling filters and activated sludge processes. Trickling filters use microorganisms attached to media to treat wastewater as it trickles down. Activated sludge processes use air and microorganisms in suspension to treat wastewater in aeration tanks, with the treated wastewater then sent to secondary clarifiers. Design considerations for biological wastewater treatment systems include organic loading rates, hydraulic loading rates, and detention
IRJET- Grey Water Treatment by Water Hyacinth-A ReviewIRJET Journal
This document summarizes research on using water hyacinth plants to treat greywater. It discusses how water hyacinth systems function as horizontal trickling filters that provide a surface for bacterial biofilms to degrade organic matter. The literature review summarizes several studies that found water hyacinth and other aquatic plants like lotus and hydrilla were effective at removing pollutants like BOD, COD, nutrients, and bacteria from domestic wastewater through physical and biochemical processes. The document also outlines a proposed method for a study using floating rafts of water lily and canna plants to treat domestic wastewater through phyto-remediation and absorption of nutrients like nitrogen and phosphorus.
The document discusses the design of water and wastewater management systems. It covers topics like water scarcity globally, evolution of wastewater systems, treatment process fundamentals and selections, and different treatment technologies. Key treatment technologies discussed include activated sludge process, aerated lagoons, trickling filters, rotating biological contactors, and sequencing batch reactors. Design considerations like hydraulic retention time, solid retention time, organic loading rates, and aeration requirements are also summarized.
The document discusses scientific approaches to inhibiting the transformation of water-based process fluids. It aims to develop chemical technologies and equipment for slowing transformation through new scientific solutions. The research seeks to establish theoretical foundations for inhibition processes based on mass transfer and hydrodynamic theories. It analyzes factors causing rapid fluid changes and outlines tasks to define transformation indicators, develop inhibition methods, and create resource-efficient technologies to maintain fluid quality for over one year of use.
The document discusses how reverse osmosis is used to reduce total dissolved solids in treated wastewater effluent for water recycling purposes. It explains that reverse osmosis uses pressure to force water through a semi-permeable membrane, retaining dissolved solids on one side. Secondary treated wastewater can effectively be processed through reverse osmosis, but upsets in secondary treatment can cause membrane fouling issues. Pretreating effluent with ultrafiltration or membrane bioreactors helps improve suspended solids removal and protects reverse osmosis membranes.
IRJET- Characterisation of Grey Water and Treatment using Moving Bed Biof...IRJET Journal
This document summarizes a study that characterized greywater and treated it using a Moving Bed Biofilm Reactor (MBBR). The study investigated how various factors like flow rate, hydraulic retention time, and MBBR fill rate affected the reactor's performance in removing organic matter from greywater. The researchers found that a flow rate of 60 L/d, hydraulic retention time of 36 hours, and MBBR fill rate of 30% produced the highest COD removal efficiency of 87.45%. The MBBR media provided a large surface area for microbial growth and effectively treated greywater.
The document discusses biological treatment as a method for removing contaminants from wastewater. It describes how bacteria and microorganisms break down organic materials through assimilation. There are various physical, chemical, and biological treatment methods outlined, with biological treatment being the focus. The key types of biological treatment systems discussed are activated sludge treatment, trickling filtration, and constructed wetlands. The document provides details on the process, equipment, advantages, and output quality of biological wastewater treatment.
GFW Office Hours: How to Use Planet Imagery on Global Forest Watch_June 11, 2024Global Forest Watch
Earlier this year, we hosted a webinar on Deforestation Exposed: Using High Resolution Satellite Imagery to Investigate Forest Clearing.
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Trichogramma spp. is an efficient egg parasitoids that potentially assist to manage the insect-pests from the field condition by parasiting the host eggs. To mass culture this egg parasitoids effectively, we need to culture another stored grain pest- Rice Meal Moth (Corcyra Cephalonica). After rearing this pest, the eggs of Corcyra will carry the potential Trichogramma spp., which is an Hymenopteran Wasp. The detailed Methodologies of rearing both Corcyra Cephalonica and Trichogramma spp. have described on this ppt.
1. 64
INGENIERÍA HIDRÁULICA Y AMBIENTAL, VOL. XLI, No. 2, May-Ago 2020, p. 64-74
recibido: Octubre 2019 aprobado: Marzo 2020
Criterios de diseño y escalado de biodiscos para el tratamiento de
aguas residuales
Carlos Menéndez Gutiérrez e-mail: carlosm@tesla.cujae.edu.cu
Centro de Estudios de Ingeniería de Procesos (CIPRO), Fac. de Ing. Química, Universidad
Tecnológica de La Habana José Antonio Echeverría (Cujae). Marianao. La Habana. Cuba.
Jaime Dueñas Moreno e-mail: jaimedm89@gmail.com
Lab. Ing. Química Ambiental, SEPI-ESIQIE del Instituto Politécnico Nacional, Zacatenco,
Ciudad de México, México.
RESUMEN
En el trabajo se ofrece una visión general de las características de los biodiscos para el
tratamiento de aguas residuales, así como algunas de sus principales ventajas y desventajas. De
igual manera, sin proponer una metodología para su diseño, se brindan elementos para el mismo,
y criterios de las variables de operación.
Palabras clave: aguas residuales, biodiscos, escalado, diseño.
Design and scaleup criteria of biodiscs for wastewater treatment
ABSTRACT
The paper offers an overview of the characteristics of biodiscs for wastewater treatment, as well
as some of its main advantages and disadvantages. In the same way, without providing a
methodology for its design, elements for it and criteria of the operation variables are provided.
Keywords: wastewater, biodiscs, scaling, design
2. Carlos Menéndez Gutiérrez, Jaime Dueñas Moreno
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INTRODUCCIÓN
El reactor biológico de discos rotatorios o biodiscos forma parte de los llamados procesos de
biopelícula, constituyendo una variante de depuración de aguas residuales que puede brindar
resultados comparables con cualquier otro tipo de sistema de depuración convencional. Las
reducciones del contenido de materia orgánica (expresada como Demanda Bioquímica de
Oxígeno (DBO) o Demanda Química de Oxígeno (DQO)) obtenidas por este sistema de
tratamiento, pueden variar entre 80 y 95 % para aguas residuales municipales, pudiéndose
obtener además altos niveles de nitrificación (Eckenfelder 1989).
Los biodiscos son básicamente instalaciones de discos con superficie cubierta de biomasa en
condiciones aerobias que, en régimen continuo, consumen materia orgánica presente en el agua
residual afluente. Es además considerada parte de las tecnologías de tratamiento biológico
secundario del tipo de crecimiento de biomasa adherida a un soporte, o reactor de película fija.
Desde el punto de vista estructural consisten en placas sintéticas que rotan montadas sobre un eje
horizontal a velocidad variable, sumergidas parcialmente en un tanque donde está contenida el
agua residual, figura 1.
Figura 1. Esquema de biodisco
El primer biodisco para el tratamiento de aguas residuales de origen industrial que registra la
literatura fue instalado en los años 60 del siglo pasado en Alemania. A partir de ese momento,
debido a su sencillez, simplicidad y economía en su funcionamiento, fue introducido en
Inglaterra y Estados Unidos, países donde su aplicación se extendió a partir del desarrollo de
nuevos materiales para la construcción de los discos, y el bajo requerimiento de energía en
comparación con otras tecnologías de tratamiento. De esta manera su aplicación fue ascendiendo
en todo el mundo. Para el año 1978 ya se había reportado 59 plantas de biodiscos en Estados
Unidos, 308 en 1980 y más de 600 en 1988. En Japón, en 1985 sobrepasaban las 1 300 plantas
(Castillo et al. 2007). En esa época ya había más de 3 000 plantas de biodiscos en todo el mundo
(Romero Rojas 2008).
Posteriormente su empleo se vio limitado como consecuencia de problemas de operación
observados en algunas plantas que utilizaban esta tecnología, como los ocasionados por la poca
resistencia mecánica de los ejes de soporte empleados hasta ese momento y variaciones no
deseadas en la velocidad de rotación de los discos. Recientes investigaciones asociadas con los
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biodiscos, y su introducción en plantas de tratamiento combinados con reactores anaerobios de
flujo ascendente, han reconsiderado los biodiscos como una opción tecnológica para el
tratamiento de aguas residuales municipales, fundamentalmente para pequeñas y medianas áreas
urbanas (Patwardhan 2003), (Panchana y Kristtel 2017).
Los biodiscos emplean el mismo principio de los filtros percoladores, pero en lugar de estar
constituidos por un medio estático (empaque), el medio soporte rota. Los discos giran alrededor
de un eje central a una velocidad comprendida entre 1 y 5 rpm, con una parte de su área
sumergida y otra expuesta al aire, alternándose ambas. La rotación del disco induce la
transferencia de oxígeno y mantiene la biomasa en condiciones aerobias. El área sumergida
comprende entre el 35 y 40% de la superficie total de los discos (Von Sperling 2007). Cuando la
sección del disco está sumergida, la biomasa adherida a ella consume materia orgánica presente
en el agua residual, mientras que, durante su exposición al aire, la biopelícula arrastra una capa
de agua que escurre sobre la superficie del disco y absorbe oxígeno. De esta manera, la
biopelícula consume materia orgánica y oxígeno para su desarrollo, propiciando la disminución
de la demanda de oxígeno del agua residual.
DESARROLLO
Configuración de los sistemas de biodiscos
Los sistemas de biodiscos pueden ser instalados según diferentes arreglos, ya sea en serie, en
paralelo, o con una configuración mixta, figura 2.
(a) (b)
Figura 2. Posibilidad de arreglos de biodiscos: en serie (a) y en paralelo (b)
Los biodiscos pueden diseñarse de uno o varios módulos y a su vez cada módulo se dispone
en etapas o secciones, generalmente no menos de tres como se muestra en la figura 3. El agua
entra en la primera etapa y avanza hacia las siguientes, cada una con un mezclado completo en la
cual tiene lugar la degradación de la DBO, al mismo tiempo que los microorganismos consumen
oxígeno, se produce el crecimiento de la biopelícula y ocurre el desprendimiento de biomasa,
todo ello en equilibrio dinámico.
Aflue
nte
Efluen
te
Eflue
nte
Afluen
te
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Figura 3. Esquema de biodiscos de 4 secciones con sedimentador secundario
[Castillo et al. (2007)]
Las etapas se comunican entre sí, permitiendo el paso del flujo de agua, usualmente en
paralelo al eje que sustenta los discos, pero también puede fluir en sentido perpendicular.
Además, se debe acoplar un sedimentador primario y otro secundario. Cuando se trata de
pequeños caudales pueden emplearse sistemas de biodiscos compactos que ya poseen
incorporado el sedimentador secundario.
Características de la biopelícula
La composición microbiológica de la biopelícula varía en la misma dirección y sentido en que
se mueve el flujo del agua residual a través de las sucesivas etapas del reactor. La diversidad de
microorganismos que se desarrollan da origen a un cultivo mixto. La variedad y proporción de
estos depende de parámetros tanto operacionales como ambientales. Los factores que determinan
las características de la biopelícula son: carga hidráulica y orgánica a las que opera el biodisco,
velocidad de rotación de los discos, composición del agua residual, pH, temperatura y
disponibilidad de oxígeno, Cortez et al. (2008).
El aumento en la velocidad de rotación de los discos incrementa la concentración de oxígeno
disuelto disponible para los microorganismos y como resultado, se encontrarán en mejores
condiciones para degradar en medio aerobio el sustrato (DBO-DQO). Sin embargo, por otra
parte, el incremento de la velocidad de rotación exige mayor consumo de potencia, gravitando
negativamente sobre la economía del proceso. Adicionalmente, el aumento de la velocidad a la
que se mueven los discos con relación al agua residual puede favorecer el desprendimiento
excesivo de la biomasa de los discos.
Al inicio y en las primeras etapas del proceso, la biopelícula, de aspecto gelatinoso,
generalmente presenta coloración gris con zonas blancas, como consecuencia de la presencia de
bacterias filamentosas. A medida que el proceso transcurre a lo largo de las etapas, el color se
vuelve carmelita o rojizo marrón, de carácter menos filamentoso y puede denotarse no solamente
la presencia de ciliados, sino también de flagelados, amebas y metazoos. La biopelícula gris es
indicativa de degradación de materia orgánica por los organismos heterótrofos. En cambio,
cuando se torna amarronada rojiza es un indicador de que predominan microorganismos
nitrificantes. La nitrificación es un proceso que se da muy bien en las últimas etapas de los
biodiscos, Salvador et al. (2004).
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El crecimiento de la biopelícula continúa hasta que las capas profundas cercanas a la
superficie del disco reciben menos oxígeno o no lo reciben en absoluto. En régimen estacionario
una fracción de la biomasa adherida se desprende debido al esfuerzo cortante disco-agua que se
origina durante el movimiento rotatorio de los discos y a la generación de gases en la capa más
interna de la biomasa, manteniéndose con un espesor prácticamente constante.
La biomasa desprendida se mantiene en suspensión por la agitación promovida por la rotación
de los discos hasta que el flujo de agua la extrae del sistema pasándola a través de un
sedimentador secundario. En este fenómeno influye la velocidad de rotación de los discos y su
diámetro.
Estudios que relacionan el espesor de la biopelícula con la eficiencia de remoción o de
reducción estiman que el espesor activo de la biopelícula está comprendido entre 20 y 600 μm,
aunque la capa de biomasa desarrollada puede ser de 1 a 4 mm de espesor (aproximadamente
equivalente en un sistema de biomasa en suspensión a 2 500 – 10 000 mg/L). Para espesores
mayores al del espesor activo, las limitaciones de oxígeno y de sustrato determinan la
ineficiencia en la remoción (Basnilla 1993). En el espesor de la biopelícula también influye la
velocidad de flujo de agua, disminuyendo considerablemente con los aumentos de la velocidad
de rotación de los discos.
Producción de lodo
La producción y características de la biomasa que se genera en los biodiscos son básicamente
las mismas que se presentan en los filtros percoladores, alrededor de 0,75 a 1,0 kg SST (kg DBO
removido)-1
(ecuación (1), con una relación SSV/SST entre 0,75 y 0,85.
∆𝑃 = 𝑌∆𝐷𝐵𝑂 (1)
donde:
ΔP: biomasa producida (base seca) kg SST.d-1
Y: rendimiento kg SST (kg DBOremovido)-1
ΔDBO: flujo másico de DBO removido kg.d-1
Características de los discos
Actualmente se comercializan discos de diferentes materiales. Inicialmente fueron construidos
de madera, posteriormente de material plástico y hoy se fabrican mayoritariamente de espuma de
poliestireno, cloruro de polivinilo y polietileno. Los de polietileno de alta densidad pueden
poseer un área específica con valores de hasta 120 m2
m-3
, diámetro de 3,5 m y estar configurados
en unidades de 8 m de longitud. Tales unidades llegan a poseer una superficie total de 9 200 m2
.
Como en todo proceso de biopelícula, el diseño debe prever la tupición o atascamiento del
medio soporte. En ese sentido, cuando se dispone de varias etapas, la separación de los discos
puede ser variable de etapa a etapa.
En las primeras, los discos se colocan más separados, mientras que en las etapas intermedias y
finales se instalan más próximos teniendo en cuenta que la biopelícula alcanzará menor espesor,
como se muestra en la figura 4. A los efectos del dimensionamiento, debe considerarse que la
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producción específica de lodos no será inferior a 0,75 kg de sólidos suspendidos /kg DBO5
removido.
Figura 4. Sistema de biodiscos para pruebas a escala de laboratorio
[Ordóñez y Betancourt (2003)]
Principales ventajas y desventajas de la tecnología
Ventajas
Admiten grandes fluctuaciones en la carga hidráulica y orgánica.
El requerimiento de área de tratamiento es menor que el de otras tecnologías de
tratamiento biológico de aguas residuales.
Es de estructura modular, lo que permite flexibilidad en el diseño.
El consumo energético es relativamente bajo, por tratarse de materiales de poco peso y su
reducida velocidad de giro.
El sistema, bien operado, casi no genera ruidos y no produce malos olores.
Puede ser eficaz como complemento a otros sistemas de tratamiento.
Alta eficiencia de remoción de carbono y nitrógeno.
Tiempos de retención cortos.
Bajos costos de instalación, operación y mantenimiento.
Lodos de buena sedimentabilidad.
Generalmente no necesita recirculación de efluente ni de lodos.
No requiere personal especializado para el mantenimiento que controle las constantes del
proceso, ya que se autorregula con facilidad.
Su impacto ambiental negativo es bajo
Desventajas
El proceso es relativamente nuevo y los parámetros de diseño no se encuentran bien
definidos.
No es fácil definirlo con un modelo matemático simple debido a que están presentes en el
proceso tres fases: gaseosa, líquida y sólida.
El proceso que tiene lugar demora en alcanzar estabilidad.
Elevado costo de inversión, aunque puede compensarse con el bajo costo de operación.
7. Criterios de diseño y escalado de biodiscos para el tratamiento de aguas residuales
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Problemas en la operación de los biodiscos
Las dificultades durante la operación con biodiscos pueden provenir; al igual que en otros
procesos biológicos, por diferentes causas. Las más comunes son:
1. Pérdida de biomasa
2. Desarrollo de biomasa blanca
3. Disminución de la eficiencia depuradora
1. Pérdida de biomasa
En ocasiones puede ocurrir el desprendimiento excesivo de la biomasa adherida a los discos.
Esto puede ser motivado por la introducción de sustancias tóxicas en el afluente, incremento
abrupto del flujo de agua residual o aumento de la velocidad de rotación de los discos.
El desprendimiento de la biopelícula se presenta por condiciones ambientales adversas para el
desarrollo de la comunidad microbiológica, como variaciones extremas de pH y entrada de
sustancias toxicas. Para evitar estos inconvenientes, se debe controlar la entrada de tóxicos,
controlar las variaciones de pH mediante sustancias neutralizadoras o amortiguadoras y
compensar la entrada de flujo.
En caso de que las causas no sean por las anteriormente descritas, debe observarse si el
desprendimiento de la biopelícula se está presentado por el giro rápido de los discos, en caso de
ser así, debe reducirse la velocidad de rotación para evitar el problema.
2. Desarrollo de biomasa blanca
El predominio del color blanco en la biomasa que se forma no es común. El desarrollo de
organismos blancos denota la presencia de thiotrix o beggiatoa en determinadas áreas, y se
refleja posteriormente en una reducción de la eficiencia en la depuración.
Estas son bacterias filamentosas autótrofas oxidantes de azufre y se desarrolla cuando hay alta
concentración de sulfuros, bajos niveles de oxígeno disuelto y sobrecarga en la primera etapa.
Como estas se desarrollan en la biopelícula, compiten con los organismos heterótrofos que
degradan la DBO y por lo tanto bajan las eficiencias de remoción (Romero Rojas 2008).
Además, este tipo de microorganismos pueden proveer nutrientes para la formación de
Bacterias Sulfato Reductoras (BRS) (Mba 2003). Cuando las BRS se desarrollan, se empieza a
generar sulfuro de hidrógeno con la aparición de olores indeseados y molestos para la comunidad
circundante.
Para solventar este problema es necesario aumentar la velocidad de aireación en el reactor,
disminuir la carga orgánica aplicada, ajustar o eliminar la división entre la etapa 1 y 2 para
incrementar el área superficial disponible para la primera etapa y/o agregar temporalmente algún
compuesto oxidante como nitrato de sodio o peróxido de hidrogeno al afluente (Cortez et al.
(2008).
Ayoub et al. (2004) reportan el control del crecimiento de la beggiatoa distribuyendo el
afluente en varias etapas del reactor. De esta manera se aumentó el oxígeno disuelto en la
primera etapa y se evitaron condiciones de sobrecarga en la misma.
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3. Disminución de la eficiencia depuradora
La disminución del rendimiento puede deberse a causas, como:
Variación notable del caudal.
Variación notable de la carga orgánica.
Alteraciones del pH. El agua residual tiene un pH normal entre 6,5 y 8,5. Si este valor se
altera por algún tiempo, afectará al correcto funcionamiento del sistema.
Acumulación de sólidos en los discos. Este problema puede ser causado por un
inadecuado pretratamiento que favorezca la disminución de sólidos suspendidos que
llegan al reactor biológico. Si la eliminación de sólidos que llegan al proceso es
inadecuada, la transferencia de oxígeno al medio puede verse disminuida, propiciando, en
casos extremos, la formación de condiciones anaerobias
Criterios para el diseño
Como en todo reactor biológico, el tiempo de retención hidráulico reviste importancia. Por
supuesto que un incremento en el régimen de flujo puede llegar a incidir significativamente en el
tiempo de retención hidráulico, más aún cuando estos sistemas comúnmente no utilizan
recirculación. Por ello, cuando se espera que el pico diario de flujo pueda llegar a ser 2,5 veces el
valor del flujo promedio, se recomienda la instalación de compensadores de flujo (equalization
tanks).
Los criterios que recomienda la Water Pollution Control Federation para la operación
mediante biodiscos con aguas residuales municipales se mencionan a continuación:
Área sumergida: 40 %
Número mínimo de etapas de una sección: 4
Mejor relación volumen-superficie: 4,89 Lm-2
para un afluente con concentraciones
mayores de 300 mgL-1
de DBO
Carga hidráulica:
81 a 163 Lm-2
d-1
para obtener en el efluente de 15 a 30 mgL-1
de DBO y SST
31 a 81 Lm-2
d-1
para obtener en el efluente de 7 a 12 mgL-1
de DBO y SST y 1 mgL-1
o
menos de nitrógeno amoniacal.
Temperatura:
13º a 32ºC, apropiada para climas tropicales
Velocidad del sobrenadante del sedimentador secundario:
32 593 Lm-2
d-1
para obtener en el efluente de 20 a 30 mgL-1
de SST.
16 300 a 24 445 Lm-2
d-1
para obtener en el efluente 10 mgL-1
de SST.
16 300 Lm-2
d-1
de flujo promedio cuando diariamente la relación pico promedio equivale
o excede 2:1.
24 445 Lm-2
d-1
cuando la relación pico promedio es menor que 2:1.
Metcalf and Eddy et al. (2007) sugieren conservadoramente para el tratamiento de aguas
residuales de origen doméstico, valores máximos en el intervalo comprendido entre 2 y 30 g
DBO m-2
d-1
.
9. Criterios de diseño y escalado de biodiscos para el tratamiento de aguas residuales
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Hay que tomar en consideración que ese tipo de literatura generalmente refleja experiencias
de países de climas templados donde las velocidades de degradación son menores que las que se
obtienen en zonas tropicales.
Para este tipo de agua residual la carga orgánica, considerando la DBO soluble, se encuentra
comprendida entre 30 y 150 g DBO (m-2
.d-1
).
Valores altos de carga orgánica propician el crecimiento excesivo de biomasa en la primera
etapa del biodisco, con las consecuencias propias que ello implica.
Escalado en los biodiscos
No hay mucha información disponible acerca del escalado de los biodiscos a partir de
información obtenida en el laboratorio o a escala de banco. Adicionalmente a la similitud en el
valor de la carga hidráulica, la atención se ha centrado principalmente en la velocidad periférica
de los discos. Por supuesto que esta velocidad depende del diámetro del disco y la velocidad de
rotación.
Los incrementos en la eficiencia de remoción con el aumento de la velocidad periférica de los
discos pueden darse hasta valores de 0,3 m.s-1
para una velocidad de rotación de 1,6 rpm para
discos de 3,7 m de diámetro para una instalación a escala industrial.
Sin embargo, como el espesor de la biopelícula depende en cierto grado del esfuerzo cortante
líquido-disco, más importante que la eficiencia de remoción, la velocidad periférica puede
constituir un elemento válido a considerar para el escalado en cuanto al espesor de la biopelícula.
La velocidad periférica puede calcularse según la ecuación (2),
𝑉
𝑝 = 𝛺𝑟 = 2𝜋𝑤𝑟 = 𝜋𝑤𝑑 (2)
donde:
Vp: velocidad periférica m.min-1
r: radio del disco, m
d: diámetro del disco, m
w: velocidad de rotación, rpm
Ω: velocidad angular, rad/min
Esto quiere decir que un disco de 0,25 m de diámetro, alcanza una velocidad periférica de 0,3
m.s-1
, girando a 2,3 rpm. Por supuesto a escala de laboratorio la misma velocidad de rotación no
da lugar a la misma velocidad periférica, entre otros factores, por el diámetro de los discos
(ecuación (3).
𝜏𝑠 = 10−3
𝑟0,5𝛺1,5
(3)
donde:
τs : esfuerzo cortante, N.m-2
r: radio del disco, m
ρ: densidad del líquido, kg.m-3
10. Carlos Menéndez Gutiérrez, Jaime Dueñas Moreno
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ν: velocidad cinemática del líquido, centistokes (10-6
m2
s-1
)
Ω: velocidad angular, rad/min
Para el escalado, la información que se logra en el laboratorio o planta piloto puede constituir
una base para el diseño de biodiscos de mayores dimensiones si se obtiene una solución de
compromiso entre la carga hidráulica y el esfuerzo cortante sobre los discos.
Una vez determinada al área total de disco necesaria, y el área de cada uno, corresponde
determinar la longitud necesaria de eje, según la ecuación (4):
𝐿 =
(𝑒+𝑝)
𝑁
(4)
donde:
L: longitud del eje (m)
N: número de discos
e: espesor de los discos (cm)
p: distancia entre discos (cm)
La distancia entre discos más común es 3-4 cm. Se recomienda que la distancia entre el borde
inferior de la batería de discos y fondo del reactor sea aproximadamente de 5 cm.
La realización de pruebas a escala de laboratorio y aplicar criterios de escalado antes de
proceder a trabajar a nivel de banco puede contribuir significativamente a una mayor economía
de todo tipo en la investigación.
CONCLUSIONES
Los biodiscos forman parte de las tecnologías de tratamiento aerobio de aguas residuales
dentro de la variante de biomasa adherida a un medio soporte. Las posibilidades de ser
concebidos modularmente le brindan versatilidad y mayores posibilidades de operación, con
eficiencias en la remoción de DBO y DQO similares a las que se obtienen con los filtros
percoladores.
En ensayos a escala semi-piloto, no reportadas aquí, efectuados hace unos años en la
Universidad Tecnológica de La Habana José Antonio Echeverría, se demostró la alta eficiencia
depuradora de los biosdiscos y además la posibilidad de obtener nitrificación y desnitrificación
en albañales mediante esta tecnología.
Las características generales de los biodiscos y los resultados que pueden obtenerse con su
implementación, ameritan que se les dedique mayor atención, fundamentalmente para su empleo
para el tratamiento de aguas residuales de caudales medios y pequeños.
Considerando que la mayor parte de la literatura reportada procede de climas templados, se
hace sugestivo el propósito de continuar la realización de investigaciones en condiciones de
campo en otras condiciones de clima.
11. Criterios de diseño y escalado de biodiscos para el tratamiento de aguas residuales
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Conflicto de intereses
Los autores declaran que no existen conflictos de intereses.
Contribución de los autores
Carlos Menéndez Gutiérrez https://orcid.org/0000-0002-5120-8106
Participó en el diseño de la investigación y en el estudio y selección de los aspectos a tratar.
Participó en la redacción del informe.
Jaime Dueñas Moreno https://orcid.org/0000-0003-0844-6042
Realizó contribuciones en la interpretación de los datos. Participó en el diseño de la
investigación, análisis de los resultados y en la revisión y redacción del informe final.