Behaviour of bisphenol A (BPA), 4-nonylphenol (4-NP) and 4-nonylphenol ethoxylates (4-NP1EO, 4-NP2EO) in oxidative water treatment processes

Endocrine disrupting chemicals (EDCs) such as natural and synthetic hormones or industrial chemicals can adversely affect the endocrine system at very low concentrations. As such substances can be present in raw water used for drinking-water production, they potentially pose a health risk to humans. In this study laboratory tests were performed to determine removal efficiencies of selected oxidative drinking water treatment processes, namely ozonation (1.4 mg/l O3) and chlorination, using sodium hypochlorite (0.5 mg/l NaClO) and chlorine dioxide (0.4-0.6 mg/l ClO2) under conditions applied in technical plants. 500-300,000 ng/l of bisphenol A (BPA), 4-nonylphenol (4-NP) and 4-nonylphenol-n-ethoxylates (NPnEO) were selected for investigations and measured by HPLC/FLD and HPLC/MS. To investigate possible oxidation by-products, adsorbable organic halogens (AOX) were determined and estrogenic activities were assessed with the help of an estrogen receptor binding assay (YES). Ozonation and chlorination with ClO2 removed both 4-NP and BPA below detection limits, corresponding with AOX and estrogenic activity. Concerning NPnEO ozonation removed NP1EO and NP2EO up to 28% and 30%, respectively, whereas ClO2 showed high removal efficiencies, eliminating >94% and 92%, respectively. NaClO removed 4-NP and BPA below detection limits, but estrogenic activities increased and AOX could be measured. NP1EO and NP2EO were only marginally reduced corresponding to the slight decrease of estrogenic potential.