Removal of emerging contaminants in conventional and advanced biological wastewater treatment plants in India-a comparison of treatment technologies

Emerging contaminants (ECs) are a growing concern for the environment and human health. The study in-vestigates 20 commonly reported ECs in 10 wastewater treatment plants (WWTPs) in urban to semi-urban set-tlements of north India over two years in the summer and winter. The selected plants were based on waste stabilization pond (WSP), up-flow anaerobic sludge blanket (UASB), activated sludge process (ASP), anoxic -aerobic process (AO), anaerobic-anoxic-oxic process, biodenipho process, sequencing batch reactor, and densadeg-biofor process. Of the 20 ECs, all 20 were identified in the influent and effluent, and 13 were identified in the final sludge on at least one occasion. The concentration in the influent, effluent, and sludge varied in the range from 2.5 ng/L to 77.4 mu g/L, below limit of detection (LOD) to 1.984 mu g/L, and < LOD to 1.41 mu g/g, respectively. Acetaminophen and caffeine were predominately detected in the influent, whereas naproxen, ciprofloxacin, and carbamazepine were predominant in the effluent. The total removal in the plants was found in the range of 40.3-68.6%, mainly attributed to biodegradation/biotransformation. Removal of ECs by WWTPs, ranked by a relative removal criterion, followed the order: Biological nutrient removal based plants > WSP > UASB > densadeg-biofor > AO > ASP > combitreat-SBR. The risk assessment showed the risk to algae from antibiotics and triclosan, daphnia from triclosan, and fish from triclosan and hormones.

Automated summary

This study investigates the presence of 20 emerging contaminants (ECs) in wastewater treatment plants (WWTPs) in north India, and found that all 20 ECs were identified in the influent and effluent, and 13 were identified in the final sludge. The removal of ECs in the WWTPs was mainly attributed to biodegradation/biotransformation. The risk assessment showed potential risks to algae, daphnia, and fish from certain ECs.