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S.A. Trikannad
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With the growing population and economic development, there is more stress on natural water resources. Additionally, current and future water shortages, increasing environmental concerns and stringent discharge standards demand high-quality treated water. In this scenario, it is crucial to recover water and wastewater resources for reuse, reducing the dependency on new resources. While aiming for water reclamation, the influence of wastewater quality parameters on human health is given foremost attention in recent times. Enteric pathogens are a major concern when reclaiming municipal wastewater. Electrocoagulation (EC) process that introduces coagulants by electrochemical means has been successfully employed for the treatment of groundwater, industrial and municipal wastewater. EC has been widely accepted over other physicochemical processes due to its process design and lowcost material. In this research, EC has been thoroughly investigated as a tertiary treatment technology for water reclamation from municipal wastewater.
This research is focused on determining the efficiency of low voltage iron EC for the removal of enteric pathogen indicators and antibiotic-resistant bacteria from secondary wastewater effluent. The effect of operational parameters: charge dosage (C/L) and charge dosage rate (C/L/min) on pollutant reduction was evaluated in different water matrices: demineralized water, synthetic wastewater effluent and real wastewater effluent. EC operated at 400 C/L, 7.2 C/L/min and natural pH allowed > 3.5 log units removal for E. coli and Enterococci, > 2.5 log units for ESBL E. coli and VRE and > 2 and 2.7 log units for Somatic coliphages and Clostridium perfringens spores respectively in real wastewater effluent. Furthermore, a significant reduction of phosphorous, COD and the true color was observed at 400 C/L and 36 C/L/min. Pollutant reduction was influenced by sedimentation and floatation mechanisms observed at varying charge dosage rates.
A marginally higher removal rate constant of pathogen indicators as a function of charge dosage at low charge dosage rate showed slow iron dosing to improve microbial adsorption and increase contact time with iron precipitates. The reduction of pathogen indicators was associated with physical removal mechanisms like adsorption, sweep coagulation and entrapment within the flocs, charge neutralization and aggregation based on literature. The effective removal of physical, chemical and microbiological parameters in real wastewater effluent was achieved at 400 C/L and 7.2 C/L/min at an operating cost of 0.17 €/m3 indicating EC to be a cost-effective treatment in comparison to alternative technologies like ozone, UV, activated carbon and reverse osmosis.
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With the growing population and economic development, there is more stress on natural water resources. Additionally, current and future water shortages, increasing environmental concerns and stringent discharge standards demand high-quality treated water. In this scenario, it is crucial to recover water and wastewater resources for reuse, reducing the dependency on new resources. While aiming for water reclamation, the influence of wastewater quality parameters on human health is given foremost attention in recent times. Enteric pathogens are a major concern when reclaiming municipal wastewater. Electrocoagulation (EC) process that introduces coagulants by electrochemical means has been successfully employed for the treatment of groundwater, industrial and municipal wastewater. EC has been widely accepted over other physicochemical processes due to its process design and lowcost material. In this research, EC has been thoroughly investigated as a tertiary treatment technology for water reclamation from municipal wastewater.
This research is focused on determining the efficiency of low voltage iron EC for the removal of enteric pathogen indicators and antibiotic-resistant bacteria from secondary wastewater effluent. The effect of operational parameters: charge dosage (C/L) and charge dosage rate (C/L/min) on pollutant reduction was evaluated in different water matrices: demineralized water, synthetic wastewater effluent and real wastewater effluent. EC operated at 400 C/L, 7.2 C/L/min and natural pH allowed > 3.5 log units removal for E. coli and Enterococci, > 2.5 log units for ESBL E. coli and VRE and > 2 and 2.7 log units for Somatic coliphages and Clostridium perfringens spores respectively in real wastewater effluent. Furthermore, a significant reduction of phosphorous, COD and the true color was observed at 400 C/L and 36 C/L/min. Pollutant reduction was influenced by sedimentation and floatation mechanisms observed at varying charge dosage rates.
A marginally higher removal rate constant of pathogen indicators as a function of charge dosage at low charge dosage rate showed slow iron dosing to improve microbial adsorption and increase contact time with iron precipitates. The reduction of pathogen indicators was associated with physical removal mechanisms like adsorption, sweep coagulation and entrapment within the flocs, charge neutralization and aggregation based on literature. The effective removal of physical, chemical and microbiological parameters in real wastewater effluent was achieved at 400 C/L and 7.2 C/L/min at an operating cost of 0.17 €/m3 indicating EC to be a cost-effective treatment in comparison to alternative technologies like ozone, UV, activated carbon and reverse osmosis.
Limitless usage of antibiotics has led antibiotic resistance to be one of the largest threats to world health and development. In this study, the concentrations of Extended spectrum betalactamase Escherichia coli and carbapenem resistant Escherichia Coli was assessed in a major drain in New Delhi, India. The performance of Anaerobic membrane bioreactor, photobioreactor and constructed wetlands in treating ESBL-E.coli and CRE-E.coli was evaluated. The results showed ESBL-E.coli and CRE-E.coli removal efficiencies of 99.82% and 99.69% for AnMBR, 99.62% and 99.86% for PBR and 98.1-99.3% for constructed wetlands respectively. Log10 reduction values of 2.7-3 for AnMBR, 2.8-3.2 for PBR and 1.82.3 for CWs was achieved in this study. Coupling micro-aeration with AnMBR improved the removal efficiency by 36-46%. A quantitative microbial risk assessment showed probability of infection by Enterotoxigenic E.coli (ETEC O55) post treatment to be reduced below 10-18% for AnMBR and PBR and below 20-35% for CWs. Treated effluents accounted for a high reduction in the total DALYs pppy by 63% for PBR, followed by 41.6% for AnMBR and 12.5% for CWS. ESBL-E. coli and CRE-E.coli counts decreased below the monitoring level of 103-105 for unrestricted irrigation and 104-105 for restricted irrigation as declared by WHO. Treated water was not recommended for direct consumption due to higher risk above 10%. This study exhibits the potential of these efficient and sustainable technologies in treating antibiotic resistant bacteria.
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Limitless usage of antibiotics has led antibiotic resistance to be one of the largest threats to world health and development. In this study, the concentrations of Extended spectrum betalactamase Escherichia coli and carbapenem resistant Escherichia Coli was assessed in a major drain in New Delhi, India. The performance of Anaerobic membrane bioreactor, photobioreactor and constructed wetlands in treating ESBL-E.coli and CRE-E.coli was evaluated. The results showed ESBL-E.coli and CRE-E.coli removal efficiencies of 99.82% and 99.69% for AnMBR, 99.62% and 99.86% for PBR and 98.1-99.3% for constructed wetlands respectively. Log10 reduction values of 2.7-3 for AnMBR, 2.8-3.2 for PBR and 1.82.3 for CWs was achieved in this study. Coupling micro-aeration with AnMBR improved the removal efficiency by 36-46%. A quantitative microbial risk assessment showed probability of infection by Enterotoxigenic E.coli (ETEC O55) post treatment to be reduced below 10-18% for AnMBR and PBR and below 20-35% for CWs. Treated effluents accounted for a high reduction in the total DALYs pppy by 63% for PBR, followed by 41.6% for AnMBR and 12.5% for CWS. ESBL-E. coli and CRE-E.coli counts decreased below the monitoring level of 103-105 for unrestricted irrigation and 104-105 for restricted irrigation as declared by WHO. Treated water was not recommended for direct consumption due to higher risk above 10%. This study exhibits the potential of these efficient and sustainable technologies in treating antibiotic resistant bacteria.