Occurrence, fate and risk assessment of biocides in wastewater treatment plants and aquatic environments in Thailand.

Abstract

This study investigated the occurrence and fate of 19 biocides in 8 wastewater treatment plants and receiving aquatic environments (both freshwater and estuarine systems) in Thailand. The predominant compound in wastewater and surface water was methylparaben with the maximum concentration of 15.2\u202fμg/L detected in the receiving river, while in sludge and sediment was triclocarban with the maximum concentration of 8.47\u202fμg/g in sludge. Triclosan was the main contaminants in the fish samples with the maximum concentration of 1.20\u202fμg/g. Similar results of biocides were found in the estuarine system in Pattaya city, with the maximum concentration of 185\u202fng/L in sea water for methylparaben, and 242\u202fng/g in estuarine sediment for triclocarban. The aqueous removal rates for the biocides ranged from 15% to 95% in average. The back estimated-usage and total estimated emission of Ʃ19 biocides in Thailand was 279 and 202 tons/year, respectively. Preliminary ecological risk assessment showed that clotrimazole and triclosan could pose high risks to aquatic organisms in the receiving aquatic environments.