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1B+C Abiotic Transformations + Biodegradation (MOP/30) A new biodegradable antimicrobial: 4,4'-dichloro-2-phenoxy-phenol (DCPP). Part II: Biodegradation and Aquatic Toxicity. Wolf, Th.1, Peter, R.2, Richner, P.2, 1 Solvias AG, Basel, Switzerland2 Ciba Specialty Chemicals Inc., Basel, Switzerland ABSTRACT- The biodegradability of the antimicrobial 4,4'-dichloro-2-phenoxy-phenol (DCPP) and the expected primary metabolites was investigated in different standardised biodegradation tests according to modified OECD test protocols. Sludge and water phases were taken into account in order to establish a mass balance. DCPP was tested on inherent biodegradability (Zahn-Wellens, OECD 302B) and has a primary degradation of about 99% after 28-day exposure. After sevend days a peak concentration of the microbiologically formed methyl-derivative (Methyl-DCPP) in water and sludge was observed, which completely degraded after 18 days. Other possible metabolites could not be traced due to their volatility. Thus, for a better understanding of the environmental fate of the compound, DCPP was tested in a continuously operated flow-through system simulating a communal sewage treatment plant (OECD 303A). The test was performed in tow test and control units, each plant consisting of aeration and settling tank. The elimination rate of DCPP was 99.7%. The adsorption of DCPP on the activated sludge was below 0.3%. Less than 0.3% of methyl-DCPP was measured in the treated effluent and less than 0.14% was adsorbed on the activated sludge. The ready biodegradability of DCPP was tested according to OECD 301F. DCPP as well as the expected primary metabolites were almost completely degraded. After 28 days, all measured concentrations in water and air trap were below detection limit. Furthermore, aquatic toxicity was tested on alga, daphnia and fish. DCPP shows toxicity t the aquatic environment. Key words: biodegradation, antimicrobial, activated sludge simulation test, eco-toxicology |
