Evaluation of pilot-scale drinking water treatment trains using a panel of bioassays

Chemical water quality monitoring is increasingly complemented with bioassays. The performance of drinking water treatment technologies was evaluated with bioassays. CALUX bioassays and the Ames fluctuation bioassay for mutagenicity were used to analyze the responses of raw feed water with and without a spiking mixture of organic contaminants in different pilot-scale water treatment trains applying advanced oxidation processes, reverse osmosis and filtration with activated carbon for the preparation of drinking water. In general, CALUX responses in the spiked feed water were in the same range as in the unspiked feed water, indicating that spiking did not significantly elevate the activity measured in the feed water. This observation was in line with a calculation of the combined additive behavior of the spiking mixture using bioactivities of the spiked chemicals in analog bioassays from ToxCast. This calculation gave no indication of a measurable response in the bioassays to be expected by the spiking, except for oxidative stress. Responses in the Ames fluctuation assay in most feed water were in some cases increased by advanced oxidation processes (AOPs) and mostly removed by active concentrations. The bioassay responses demonstrate the removal of emerging chemicals with different mechanisms of action by different water treatment technologies.