As a consequence of insufficient removal during treatment of wastewater released from industry and households, different classes of organic micropollutants are nowadays detected in surface and drinking water. Among these micropollutants, bioactive substances, e.g., endocrine disrupting compounds and pharmaceuticals, have been incriminated in negative effects on living organisms in aquatic biotope. Much research was done in the last years on the fate and removal of those compounds from wastewater. An important point it is to understand the role of applied treatment conditions (sludge retention time (SRT), biomass concentration, temperature, pH value, dominant class of micropollutants, etc.) for the efficiency of conventional treatment plants (CTP) and membrane bioreactors (MBR) concerning the removal of micropollutants such as pharmaceuticals, steroid- and xeno-estrogens. Nevertheless, the removal rates differ even from one compound to the other and are related to the ph ysico-chemical characteristics of the xenobiotics

The electroreduction of polychloromethanes and polychloroethanes has been studied by means of cyclic voltammetry (CV) and preparative electrolysis experiments in acetonitrile (ACN), dimethylformamide (DMF) and their admixtures with water. Silver has been used as cathode material, on account of our extended experience on its well established electrocatalytic activity toward reductive dehalogenation reactions of organic compounds. Polychloromethanes and -ethanes are common chlorinated solvents pertaining to the large family of volatile organic halides (VOH), whose high toxicity, or even carcinogenicity, demands careful treatment of contaminated soils, drinking waters and gaseous emissions. The results confirm the electrocatalytic role of silver and suggest a general route for the development of appropriate degradation processes.

This study aimed at giving a better insight into the possible fate of nonylphenol (NP) during wastewater treatment by using a lab-scale membrane bioreactor (MBR) designed and optimized for fate studies carried out with radiolabeled compounds. After a single pulse of 14C-labeled-NP isomer (4-[1-ethyl-1,3-dimethylpentyl]phenol) as radiotracer, the applied radioactivity was monitored in the MBR system over 34 days. The mass balance of NP residues at the end of the study showed that 42% of the applied radioactivity was recovered in the effluent as degradation products of NP, 21% was removed with the daily excess sludge from the MBR, and 34% was recovered as adsorbed in the component parts of the MBR. A high amount of NP was associated to the sludge during the test period, while degradation compounds were mainly found in the effluent. Partial identification of these metabolites by means of HPLC-tandem mass spectrometry coupled to radio-detection showed they are alkyl-chain oxidation products of NP. The use of this MBR and a radiolabeled test compound was found suitable for demonstrating that under the applied conditions, the elimination of NP through mineralization and volatilization processes (both less than 1%) was negligible. However, the removal of NP via sorption and the continuous release of oxidation products of NP in permeate were of relevance.

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