Biosafety assessment of effluents from different drinking water treatment process

Using recombinant yeast assay, cell proliferation assay and uterotropic assay, the estrogenic effect of Changjiang River raw water, effluent water from conventional process (flocculation + sedimentation + sand filter), effluent water from enhanced conventional process (flocculation + sedimentation + biological enhanced activity filter), and effluent water from biological activated carbon process (flocculation + sedimentation + sand filter + biological activated carbon filter) are analyzed. The results of in vitro test showed that when water sample at dosage of 0.01 to 2.43 L/plate, the curve of estrogen effect in Changjiang River raw water, effluent water from conventional process and enhanced conventional process was similar with that of 17 beta-estradiol. Their estrogen effect increased with increasing of water sample volume in certain extent, which had the dose-response relationship, and there is no estrogen effect in the effluent water from biological activated carbon process within the test's dosage range. The results of in vivo test showed that comparing with the control group at dosage of 1 to 125 L/kg, Changjiang River raw water, effluent water from conventional process and enhanced conventional process could increase the weight of rat uterus, which indicated that the organic matters in the water samples still had estrogenic effect after the metabolic transformation in body. This study demonstrates that recombinant yeast assay, cell proliferation assay and uterotropic assay can be used for assessment of safety of effluents water from different drinking water treatment process.