Electricity Generation from Biogas Produced in a Lab-Scale Anaerobic Digester...inventionjournals
The sludge produced during wastewater treatment should be stabilized in order to minimize the damage to the environment. This study includes the evaluation of sludge stabilization and biogas formation by anaerobic digestion in order to generate electricity using stirling motor.The study was carried out with the raw sludge form the thickener of the wastewatertreatment plant. The main aim of the study is to provide sludge stabilization resulting biogas production by reduction of organic matter and to generate electricity. Anaerobic digestion studies were carried out using a laboratory scale anaerobic reactor with a volume of 7L.Under themesophilic condition, the sludge age was maintained at 10 days during the first 20 days of operation, while the reactor was operated for 90 days until the end of the run, with a sludge age of 20 days.The results have changed in the range of 42-52% after the organic matter reduction obtained from the anaerobic digestion. Concentrations of 3735.7300 ppm, 5060.5768 ppm, and 6951.4013 ppm biogas were obtained. Biogas was turned on by mechanical energy with a Stirlingmotor and then turned to direct current and the lamps with 3V 20mA each were run for 60 minutes
Electricity Generation from Biogas Produced in a Lab-Scale Anaerobic Digester...inventionjournals
The sludge produced during wastewater treatment should be stabilized in order to minimize the damage to the environment. This study includes the evaluation of sludge stabilization and biogas formation by anaerobic digestion in order to generate electricity using stirling motor.The study was carried out with the raw sludge form the thickener of the wastewatertreatment plant. The main aim of the study is to provide sludge stabilization resulting biogas production by reduction of organic matter and to generate electricity. Anaerobic digestion studies were carried out using a laboratory scale anaerobic reactor with a volume of 7L.Under themesophilic condition, the sludge age was maintained at 10 days during the first 20 days of operation, while the reactor was operated for 90 days until the end of the run, with a sludge age of 20 days.The results have changed in the range of 42-52% after the organic matter reduction obtained from the anaerobic digestion. Concentrations of 3735.7300 ppm, 5060.5768 ppm, and 6951.4013 ppm biogas were obtained. Biogas was turned on by mechanical energy with a Stirlingmotor and then turned to direct current and the lamps with 3V 20mA each were run for 60 minutes
Waste to Watts: Anaerobic Digestion of Livestock Manure (Sood)Iwl Pcu
By: Dave Sood, Consultant, The presentation will cover key aspects of anaerobic digestion:
-Methane Production from Manure
-AD and Its Benefits
-AD Process
-Operating Conditions for AD
-Manure Characteristics and Digester Types
-AD and Water Quality
-Manure Characteristics and Digester Types
-Economic Analysis
-AD in Europe
-Why Digesters Fail?
-Cold Climate Digesters
-Key to Successful Digesters in Cold Climates
-A success story & Carbon Credits: Haubenschild Dairy, Minnesota, USA
Impact of Improved Aeration on Decomposition Rate of Enriched Compostijtsrd
Agricultural activities tend to generate a substantial volume of animal and crop residues. Composting is the most economical and ecologically sustainable option to manage farmyard waste. However, it takes approximately three months to complete decomposition and contains lower plant nutrient percentages than inorganic fertilisers. This study aimed to reduce the decomposition time and improve the nutrient content of compost. Aerobic decomposition was enhanced by aeration inside the pile using a blower with 0.5 l min kg airflow. Paddy straw, poultry manure, goat manure, cattle manure and paddy husk ash were mixed in 3 1 1 1 1 ratio respectively as the raw materials and 3 of Eppawala Rock Phosphate was added to the mixture in weight basis. Six piles 150 X 100 X 80 cm were prepared, and three piles were aerated for six hours per day while other three piles were left to decompose under the ambient condition as the control. According to the results, aerated and control piles took 35 days and 65 days to complete the decomposition. Total N, available P, exchangeable K, C N ratio, pH, EC and CEC were analysed in compost samples from aerated after 35 days and controls, and the results were, 20.5 g kg 1, 1.8 g kg 1, 10.4 g kg 1, 7, 8.8, 4.3 mS cm 1, 19.3 cmol kg 1 and 17.8 g kg 1, 1.5 g kg 1, 9.9 g kg 1, 8.5, 8.8, 3.64 mS cm 1, 21.3 cmol kg 1 respectively. Data were analysed using SAS 9.0 software with a 95 confidence interval. The results revealed a significant increment in total N, exchangeable K, C N ratio, EC and CEC in aerated piles compared to controls. And the nutrient composition of both methods was significantly higher than the commercial compost. Therefore, it can be concluded that decomposition time can be effectively reduced and the nutrient level can be increased by artificial aeration and nutrient enrichment, respectively. However, further studies are recommended to study the economic feasibility. D. M. S. H. Dissanayaka | V. P. T. Dhananjaya | E. J. Kosgollegedara | S. Karthigayini "Impact of Improved Aeration on Decomposition Rate of Enriched Compost" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-5 | Issue-2 , February 2021, URL: https://www.ijtsrd.com/papers/ijtsrd38557.pdf Paper Url: https://www.ijtsrd.com/engineering/agricultural-engineering/38557/impact-of-improved-aeration-on-decomposition-rate-of-enriched-compost/d-m-s-h-dissanayaka
Fuzzy logic for plant-wide control of biological wastewater treatment process...ISA Interchange
The application of control strategies is increasingly used in wastewater treatment plants with the aim of improving effluent quality and reducing operating costs. Due to concerns about the progressive growth of greenhouse gas emissions (GHG), these are also currently being evaluated in wastewater treatment plants. The present article proposes a fuzzy controller for plant-wide control of the biological wastewater treatment process. Its design is based on 14 inputs and 6 outputs in order to reduce GHG emissions, nutrient concentration in the effluent and operational costs. The article explains and shows the effect of each one of the inputs and outputs of the fuzzy controller, as well as the relationship between them. Benchmark Simulation Model no 2 Gas is used for testing the proposed control strategy. The results of simulation results show that the fuzzy controller is able to reduce GHG emissions while improving, at the same time, the common criteria of effluent quality and operational costs.
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 effect of reduction of aeration period on organic pollutants removal in s...SophieShi7
The authors investigated the possibility to reduce aeration time in one of the cycles of sequencing batch activated sludge reactors. It is known that there are microorganisms in activated sludge which can store organic materials temporarily in such forms as polyhydroxyalkanoate (PHA). It was expected that removal of organic materials in the cycle with reduced aeration was supplemented by the microbial activities to store organic materials temporarily. The authors operated sequencing batch reactors with 6 cycles/day with synthetic wastewater, and reduced aeration in one of the cycles. Short-term experiments were conducted to see the effects of aeration reduction for one time, and long-term experiments were conducted to see the effect of long term implementation of operation with aeration reduction. In both experiments, removal of DOC was greater than 92%, and no significant adverse effect was observed. The more aeration was reduced, the more PHA was carried over to the following cycles. It was estimated that about 17% to 50 % of PHA was carried over to the cycles following the cycles in which aeration was reduced. The operation with one-cycle reduced aeration was successfully implemented in the experiments. There is a big room to explore wastewater treatment technologies in the direction to flexibly control energy consumption.
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.
Waste to Watts: Anaerobic Digestion of Livestock Manure (Sood)Iwl Pcu
By: Dave Sood, Consultant, The presentation will cover key aspects of anaerobic digestion:
-Methane Production from Manure
-AD and Its Benefits
-AD Process
-Operating Conditions for AD
-Manure Characteristics and Digester Types
-AD and Water Quality
-Manure Characteristics and Digester Types
-Economic Analysis
-AD in Europe
-Why Digesters Fail?
-Cold Climate Digesters
-Key to Successful Digesters in Cold Climates
-A success story & Carbon Credits: Haubenschild Dairy, Minnesota, USA
Impact of Improved Aeration on Decomposition Rate of Enriched Compostijtsrd
Agricultural activities tend to generate a substantial volume of animal and crop residues. Composting is the most economical and ecologically sustainable option to manage farmyard waste. However, it takes approximately three months to complete decomposition and contains lower plant nutrient percentages than inorganic fertilisers. This study aimed to reduce the decomposition time and improve the nutrient content of compost. Aerobic decomposition was enhanced by aeration inside the pile using a blower with 0.5 l min kg airflow. Paddy straw, poultry manure, goat manure, cattle manure and paddy husk ash were mixed in 3 1 1 1 1 ratio respectively as the raw materials and 3 of Eppawala Rock Phosphate was added to the mixture in weight basis. Six piles 150 X 100 X 80 cm were prepared, and three piles were aerated for six hours per day while other three piles were left to decompose under the ambient condition as the control. According to the results, aerated and control piles took 35 days and 65 days to complete the decomposition. Total N, available P, exchangeable K, C N ratio, pH, EC and CEC were analysed in compost samples from aerated after 35 days and controls, and the results were, 20.5 g kg 1, 1.8 g kg 1, 10.4 g kg 1, 7, 8.8, 4.3 mS cm 1, 19.3 cmol kg 1 and 17.8 g kg 1, 1.5 g kg 1, 9.9 g kg 1, 8.5, 8.8, 3.64 mS cm 1, 21.3 cmol kg 1 respectively. Data were analysed using SAS 9.0 software with a 95 confidence interval. The results revealed a significant increment in total N, exchangeable K, C N ratio, EC and CEC in aerated piles compared to controls. And the nutrient composition of both methods was significantly higher than the commercial compost. Therefore, it can be concluded that decomposition time can be effectively reduced and the nutrient level can be increased by artificial aeration and nutrient enrichment, respectively. However, further studies are recommended to study the economic feasibility. D. M. S. H. Dissanayaka | V. P. T. Dhananjaya | E. J. Kosgollegedara | S. Karthigayini "Impact of Improved Aeration on Decomposition Rate of Enriched Compost" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-5 | Issue-2 , February 2021, URL: https://www.ijtsrd.com/papers/ijtsrd38557.pdf Paper Url: https://www.ijtsrd.com/engineering/agricultural-engineering/38557/impact-of-improved-aeration-on-decomposition-rate-of-enriched-compost/d-m-s-h-dissanayaka
Fuzzy logic for plant-wide control of biological wastewater treatment process...ISA Interchange
The application of control strategies is increasingly used in wastewater treatment plants with the aim of improving effluent quality and reducing operating costs. Due to concerns about the progressive growth of greenhouse gas emissions (GHG), these are also currently being evaluated in wastewater treatment plants. The present article proposes a fuzzy controller for plant-wide control of the biological wastewater treatment process. Its design is based on 14 inputs and 6 outputs in order to reduce GHG emissions, nutrient concentration in the effluent and operational costs. The article explains and shows the effect of each one of the inputs and outputs of the fuzzy controller, as well as the relationship between them. Benchmark Simulation Model no 2 Gas is used for testing the proposed control strategy. The results of simulation results show that the fuzzy controller is able to reduce GHG emissions while improving, at the same time, the common criteria of effluent quality and operational costs.
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 effect of reduction of aeration period on organic pollutants removal in s...SophieShi7
The authors investigated the possibility to reduce aeration time in one of the cycles of sequencing batch activated sludge reactors. It is known that there are microorganisms in activated sludge which can store organic materials temporarily in such forms as polyhydroxyalkanoate (PHA). It was expected that removal of organic materials in the cycle with reduced aeration was supplemented by the microbial activities to store organic materials temporarily. The authors operated sequencing batch reactors with 6 cycles/day with synthetic wastewater, and reduced aeration in one of the cycles. Short-term experiments were conducted to see the effects of aeration reduction for one time, and long-term experiments were conducted to see the effect of long term implementation of operation with aeration reduction. In both experiments, removal of DOC was greater than 92%, and no significant adverse effect was observed. The more aeration was reduced, the more PHA was carried over to the following cycles. It was estimated that about 17% to 50 % of PHA was carried over to the cycles following the cycles in which aeration was reduced. The operation with one-cycle reduced aeration was successfully implemented in the experiments. There is a big room to explore wastewater treatment technologies in the direction to flexibly control energy consumption.
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.
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
International Journal of Engineering and Science Invention (IJESI) inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online
Anaerobic Co-Digestion of Cassava Waste Water and Abdominal Cow Dung under Ch...IJCMESJOURNAL
Anaerobic co-digestion of cassava waste water (CWW) and abdominal cow dung (ACD)in different proportions was studied in five treatments under changing meteorological conditions. The five treatment cases T1: 100% CWW; T2: 100% ACD; T3: 90%CWW +10%ACD; T4:70%CWW+30%ACD; T5: 50%CWW+50%ACD were digested under anaerobic conditions in model batch, metallic bio digesters of same working volume (32.0 liters) for 30 days retention period. Results indicated that T2 system flamed on the 20th day, T5 on the 20th day while T1, T4 and T3 systems didn’t flame. T1 had cumulative gas yield of 12.7 liters; T2 had 28.85 liters; T3 had 12.5 liters,T4 had 11.1 liters while T5 had cumulative gas yield of 15.8 liters per 24kg mass of slurry. T2had 91.20% methane; while T5 produced 92.999% methane. Daily biogas yields were modeled as functions of meteorological parameters. Results indicated that many parameters showed good correlations with ambient temperature.
Degradation of phenol using sequential batch reactoreSAT Journals
Abstract The paper presents the experimental study on the use of Sequential Batch Reactor (SBR) for the degradation of phenol in the synthetic wastewater. SBR was used as a biological treatment for the reduction of COD, which is based on suspended growth system. The garden soil with cow dung was used as the seeding material in SBR, the micro-organisms that are present help in degradation of phenol as well as reducing the COD concentration. The parameters varied in the study were initial concentration of phenol in the synthetic wastewater, aeration rate and hydraulic retention time. The degradation study shows that the maximum phenol removal efficiency is 97% for 200 ppm of initial phenol concentration under 40 ml/min of aeration rate. The COD removal efficiency of 92.3% is achieved for 250 ppm of concentration of phenol. The variation in the aeration rate was found to be very effective in increasing the efficiency of SBR. For 600 ml/min of aeration, the removal efficiency of phenol and COD are respectively, 98% and 75%. But for the aeration rate of 200 ml/min the removal efficiency of COD is as high as 81.25%. Hence, with the increase in the aeration rate, there is an increase in the degradation rate of phenol and decrease in COD reduction. This study demonstrates the utilization of SBR in degrading high concentration of phenol. Keywords: Sequential Batch Reactor (SBR), Phenol, COD, Biological Treatment …
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.
Design of Algal Photo Bioreactor Using Recycled PET Bottles
Paineis_IWA_BEIROLAS_2016
1. EPAL - Empresa Portuguesa das Águas Livres S.A. www.epal.pt
Efficient Biological Treatment at Beirolas WWTP - critic oxygen
determination
METHODS
RESULTS
DISCUSSION
M. Pinheiro*, C.Carneiro**; E.Cardoso***; J. Martins***; M.J. Benoliel***;A. P. Teixeira***
*Tecnilab, marcia.pinheiro@tecnilab.pt
**Escola Superior de Tecnologia de Setúbal, carla.carneiro@estsetubal.ips.pt
***EPAL,e.cardoso@adp.pt;j.martins@adp.pt;mjbenoliel@adp.pt;ana.p.teixeira@adp.pt
The sampling period took place from July to September 2011.The analytical work was performed by Márcia Pinheiro
during her Master degree at EPAL WW Analyses Laboratory Department located at Beirolas WWTP.
The samples were collected 2 times a day, at 8h30 and 16h00. Two sampling points were controlled in each sampling
period: RBA e RBB, a total of 46 samples were analysed.
The StrathoxTM is a closed cell respirometer, developed by Strathkelvin Instruments, to performed rapid tests in order
to determine the activity of bacteria in activated sludge. This equipment measures the consumption of dissolved
oxygen,determiningtheoxygenuptakerate(OUR),andthespecificoxygenuptakerate(SOUR)fromaspecificmicrobial
population, providing relevant information for the biomass characterization.
ThetestsperformedwithStrathoxTMwerecarbonaceousandnitrifyingsludgehealth,respirationinhibition,nitrification
inhibition, short-term BDO, and optimization process test.
Each trial is carried on with 8 ml of activated sludge, 2 ml synthetic
compound and 10ml of deionized water. It is also performed at controlled
temperature and takes from 10 to 15 minutes or until complete oxygen
depletion, in the case of optimization process tests.
The nitrification inhibition test is performed by previously adding ATU
(allythiourea) to the sludge. Trials for determine MLSS from each sample
of mixed liquor were carried on.
CriticaloxygenconcentrationsforthebiologicalpopulationfromBeirolas
WWTP, were obtained from the performed protocol tests described.
Along with the sampling period the secondary effluent quality was
monitored by standardized accredited methods for BOD, COD, TSS and
pH weekly, and monthly for NO3, NH4 and NTK. Dissolved oxygen in the
aeration tank was monitored by on-line sensors during the sampling
period.
At that time we had implemented some energy-efficiency measures to improve performance of biological treatment,
namely reducing internal recirculation rate, aeration during peak energy consumption and precipitation events. The
implementation of those measures was progressive and weekly validated by secondary effluent characteristics like
BDO, COD and suspended solids.
The biological reactors also have monitoring probes for dissolved oxygen, redox potential and suspended solids.
Over a period of three months, from July to September, 46 trials were analysed by StrathoxTM, to determine bacteria
activity and oxygen consumption rates in the biological sludge.
The biological treatment at Beirolas WWTP has been designed as a
Bardenpho three-stage process, promoting the integrated removal
of nitrogen and carbon, with the possibility to promote biological
phosphorus removal. The process consists of three distinct zones:
anaerobic, anoxic and aerobic one. In the aerobic tank, it has four
theoretical“cells”inseries(Table1)wheretheoxidationoftheremaining
COD and ammonia occurs. The aeration system was dimensioned
on the basis of usage rates obtained from the application of the
mathematical model BioWIN.
Table 1 – Theoretical oxygen demands
Theoretical oxygen demand
Units Cell 1 Cell 2 Cell 3 Cell 4
g/m3
/h 58 51 50 49
KgO2
/d 3637 3198 1818 2349
mg/L 1 1 1 1
KgO2
/d 9534 7545 3900 4618
Nm3
/h 4983 4146 2175 2625
At the time this project was developed the main driving forces were
to achieve a good quality level of treated wastewater. This will allow
to discharge on Tagus estuary
References: Pinheiro, M. StrathoxTM, Energetic optimization and toxicity, IPS/ESTSetúbal; Steven A. Bolles Modeling watewater aeration systems to discover energy savings opportunities, Process Energy Services, LLC
Diamond, Ken, Mason, G, Daldowie SWT, Energy Optimization Programme Report.
Acknowledgement: Diamond, Ken, Strathkelvin Instruments; Póvoa, Pedro, AdP, The authors would like to thank EPAL the opportunity to participate in WWCongress IWA2016.
Beirolas WWTP is located in Lisbon in the right side of Tagus estuary. It began operating in 1989. In the late nineties it was up-graded. The plant capacity is 215.000 inhabitants which corresponds to a daily flow of 54.500m3. The plant design includes a secondary
treatment by activated sludge, a mesophilic anaerobic digestion of sludge and biogas utilization which provides thermic and electrical energy. The discharge permit allows for treated wastewater reuse.
The plant design was developed to achieve a good quality of treated wastewater and the possibility to reuse it for irrigation. The plant energy-efficiency was not a driver.
Activated sludge processes may be responsible for more than 50% of the energy consumption in a wastewater treatment plant.
The performance of the biological treatment may be compromised by several factors namely wastewater characteristics, industrial discharges, dissolved oxygen, etc. However the most limiting factor is the amount of available oxygen to bacteria growth. Activated
sludge respiration rate is the key to efficient process control. It indicates the BOD removal rate and the aeration requirements.
The treatment process and operational routines were already consolidated. At that time we were facing an adverse economic environment with lack of resources. The challenge was to adopt measures that would result in a more energy-efficient process.
As part of a Master’s thesis, a closed cell respirometer, StrathoxTM, was used to perform rapid tests in order to determine the microbial activity in the activated sludge of BeirolasWWTP.Those tests indicate the critical oxygen, i.e. the oxygen diffusion capacity in the bacterial
cell wall.Then we were able to adjust the aeration system to supply the necessary amount of oxygen to the bacterial growth, reducing de energy consumption in the biological process and simultaneously validating the energy-efficiency measures implemented.
INTRODUCTION
CONCLUSIONS
without any environmental damage and to consider
the possibility of reusing wastewater after treatment.
Energy-efficiency was not an issue. Latter cost’s issues
and operational optimizations became more and
more important. The operation process was under
control. The final effluent had very good quality and
the challenge was to optimise energy consumption
in the biological treatment without compromising
thequalityoffinaleffluent.Wegraduallyadoptedand
implemented several measures in order to achieve
those goals.
The StrathoxTM was the tool we used to a better
understanding of bacteria activity and its oxygen
needs. The tests are quick and simple. Performed in
10 to 15 minutes, with a friendly software, we can
validatedtheenergy-efficientmeasuresimplemented
on the biological process and aerated in function of
the critical oxygen point instead of a recommend
bibliography oxygen dissolved set point.
• We can operate the biological reator under 1mgO2
/L
• Ensure the quality of the final effluent
• Reduce energy consumption (<0,2Kwh/m3
)
• Methodology easy to implement to another WWTP
• One more step to wastewater resource recovery facility
Figure 1. Critical oxygen determination from July to September 2011 Figure 2. Critical oxygen concentration
Figure 4. Energy distribution by unit operation before implementing the
energy-efficient measures
Figure 5. Energy distribution by unit operation after implementing the
energy-efficient measures
Figure 6. Secondary clarifier
Figure 7. Alfaiates (Recurvirostra avoseta) nearby Beirolas WWTP discharge point