Triclosan in a sewage treatment process—balances and monitoring data

In a German sewage treatment plant that processes 200,000 m3 wastewater per day, the concentrations of 2,4,4-trichloro, 2hydroxy-phenylether (triclosan) in the in-flowing (~1000 ng l1) as well as in the out-flowing water (~50 ng l1) are compared to the concentrations measured in sludge (1200 ng g1). Considering the mass flow of water and sludge in the respective plant, balances including water and sludge are calculated. Thirty percent of the triclosan is sorbed with weak bonds to the sludge, while some amounts are sorbed as bound residues in the sludge. About 5% is dissolved in the out-flowing water. Thus most of the in-flowing material is not recovered as the parent compound but it is likely that it is transformed to other metabolites or unrecovered bound residues. These data are compared to the monitoring of sewage sludge of 20 different plants in this region, most of which are smaller, though. The concentrations found in these sludges vary from 1000–8000 ng g1.