The elimination of the endocrine disrupters 4-nonylphenol and bisphenol A during wastewater treatment - Comparison of conventional and membrane assisted biological wastewater treatment followed by an ozone treatment

A conventional biological wastewater treatment plant (BWWTP) and a membrane bio-reactor (MBR) were operated to treat municipal wastewater. The endocrine disrupting compounds (EDCs), 4-nonylphenol (4-NP) and bisphenol A (BPA; 2,2-bis-(4-hydroxyphenyl)-propane), were spiked into the feed. Additionally, the effluents were treated with ozone (O3). The elimination efficiencies of both treatment techniques and the advanced effluent treatment applying ozone were balanced over a three-week testing period by monitoring 4-NP and BPA concentrations in the feed, all effluents and excess sewage sludge. Reduction of Chemical Oxygen Demand (COD) was observed with 95 ± 2%. Substance specific analyses were performed by gas chromatography, coupled with mass spectrometry (GC-MS). Aqueous samples and sludge extracts after pressurised liquid extraction (PLE) were examined after derivatization using acetic anhydride. The spiking levels into the feed were adjusted to reach concentrations of 51.2 ± 10.1 µg/L (4-NP) and 50.7 ± 8.2 µg/L (BPA), while the effluent samples were fortified prior to ozone treatment by adding 48 µg/L or 49 µg/L of 4-NP and BPA. The elimination achieved without applying ozone were 98 or 97.8 % for 4-NP and BPA in MBR treatment and 98 and 91.6 % under conventional treatment. Balances proved biodegradation as the superior elimination mechanism for 4-NP and BPA in both treatment processes