Koya Komori

Mass balance analysis of triclosan, diethyltoluamide, crotamiton and carbamazepine in sewage treatment plants

The behavior of antibacterial triclosan, insect-repellent diethyltoluamide (DEET), anticonvulsant carbamazepine, and antipruritic crotamiton was investigated at two sewage treatment plants (STPs) to clarify their complete mass balance. Twenty-four-hour flow-proportional composite samples were collected from the influent and effluent of primary and final sedimentation tanks, a biofiltration tank and disinfection tanks. Sludge samples (i.e., activated and excess sludge) and samples of the return flow from the sludge treatment process were collected in the same manner. The analytes in both the dissolved and particulate phases were individually determined by a gas chromatograph equipped with mass spectrometer. Triclosan was dominantly detected in the particulate phase especially in the early stage of treatment (up to 83%) and was efficiently removed (over 90%) in STPs, mainly by sorption to sewage sludge. Limited removal was observed for DEET (55+/-24%), while no significant removal was demonstrated for crotamiton or carbamazepine. The solid-water distribution coefficients (K(d), n=4) for triclosan (log K(d): 3.7-5.1), DEET (1.3-1.9) and crotamiton (1.1-1.6) in the sludge samples are also determined in this study. These findings indicate the limitations of current sewage treatment techniques for the removal of these water-soluble drugs (i.e. DEET, carbamazepine, and crotamiton).

Biological effects of PPCPs on aquatic lives and evaluation of river waters affected by different wastewater treatment levels.

The existence of pharmaceuticals and personal care products (PPCPs) in the water environment is an emerging problem. In this study, we investigated the toxicity of eleven PPCPs through bioassays on bacteria, algae, crustaceans, amphibians and protozoa, and compared the toxicology indexes with the concentration of PPCPs in river water for ecotoxiclogical risk evaluation. Toxicity of the eleven PPCPs was observed and the values of EC50 or LC50 were in the order of mg/L. A distinctive finding is that antibacterial triclosan affected all aquatic lives tested. The effects of PPCPs varied according to species of lives. Contamination from PPCPs was detected at observation stations on the river, and the range of concentration was in the order of ng/L far lower than the values of toxicity indexes EC50 or LC50. Ecotoxicological risks posed by PPCPs at the observation stations was evaluated using the concentration in the river water and the NOEC examined by AGI tests. The results revealed that three PPCPs, triclosan, clarithromycin, and azithromycin, posed an ecotoxiclogical risk in rivers where wastewater treatment systems are not yet well developed.