Review On The Assessment Of The Removal Efficiency Of Wastewater Treatment Plants For Selected Xenobiotics

Wastewater treatment plants (WWTPs) represent a significant source for the input of micro pollutants as endocrine disruptors (EDs) or pharmaceutically active compounds (PhACs) into the aquatic environment. Those xenobiotics show effects to aquatic life at very low concentration e.g. by interfering with their hormone system. As a consequence investigations on the removal potential of various traditional as well as new waste water treatment technologies are undertaken in order to identify appropriate removal of xenobiotics from the urban water cycle. Beside laboratory experiments with synthetic wastewater and addition of a known concentration of the substance of interest, full scale treatment plants representing a broad range of layouts and concepts as well as a broad range of substances analyzed are investigated. In that context removal rates are calculated by comparing inflow and effluent concentration. This paper deals with a review on aspects that have to be kept in mind when assessing the removal potential of full scale wastewater treatment plants in order to avoid systematic errors and to come up with reliable results that can be compared to other plant configurations or operation types. After theoretical considerations an example for a mass balance of a complex waste water treatment plant is given to show a procedure suitable to reveal reliable information on the behavior of xenobiotics during wastewater treatment.