Antibiotic detection in a hospital wastewater and comparison of their removal rate by activated sludge and earthworm-based vermifilteration: Environmental risk assessment

Abstract

The objective of the current research was to detect some antibiotics in hospital sewage and compare their removal rates reached using a vermifilter (VF) pilot and a real activated sludge (AS) treatment system. Six target antibiotics (ciprofloxacin, ofloxacin, sulfamethoxazole, trimethoprim, tetracycline and metronidazole) prescribed in the hospital were detected in the sewage and the removal rates via the two systems were examined. Three sampling points were chosen: the raw effluents from the hospital, VF and AS. Four sampling campaigns were performed over four months. Moreover, the environmental risk assessment was performed for all the antibiotics through estimating risk quotients (RQs). All the antibiotics were quantified in all the samples taken. It was found that ciprofloxacin had the highest concentration (7505.08–14731.88ng/L). The results revealed that the VF reactor had a better and more stable performance in removal of the antibiotics than the AS system even though all the antibiotics were present in the effluents of both the processes compared. Further, according to the calculated RQs, the hospital effluent had even high risk to algae and, generally, the VF system was capable of reducing the ecotoxicity of the antibiotics. Therefore, it could be confirmed that earthworm-based vermifiltration can be considered as a promising alternative to conventional processes like AS, particularly when it comes to economic situations.