Removal Of Bisphenol A (BPA) From Simulated Domestic Wastewater By Membrane Bioreactor (MBR) And Conventional Activated Sludge Reactor (CASR)

Bisphenol A, a kind of endocrine-disrupting chemicals (EDCS), widely used monomer for epoxy resins and polycarbonates, recently, have been frequently detected in ground, surface and wastewater in many countries. The researches on technologies of BPA removal are significantly important. Membrane bioreactor (MBR) has overwhelming advantages of treating industrial wastewater, domestic wastewater, specific municipal wastewater and water reuse compared to the conventional wastewater treatments. However it has deficiency of micro molecules removal, which is significant in water reuse. Based on these facts, the comparison of BPA removal between MBR and conventional activated sludge reactor (CASR) was studied.The concentrations of BPA effluent in every stage were detected using HPLC, and the effect of different HRT and F/M on BPA removal efficiency was analyzed. Chemical oxygen demand (COD_Cr) and ammonia nitrogen (NH₄⁺-N) were measured to show if the existence of BPA had effect on their removal. Oxygen uptake rate (OUR) of sludge acclimatized and unacclimatized by BPA is measured to evaluate the activity of sludge in both MBR and CASR. Adsorption of BPA on sludge sampled from MBR and CASR was studied, and parameters were calculated. One of the biodegradation products of BPA was detected using GC-MS.The results show that both MBR and CASR have high removal efficiency of BPA, the BPA removal efficiencies were all above 95%. The variation of HRT and F/M didn't show obvious effect on the BPA removal. The removal of characteristic contaminations in both MBR and CASR approaches stabilization. The average removal efficiencies of COD_Cr are respectively 85%-90%, 70%-80% and the NH₄⁺-N removal efficiency is all above 95%. It is found that BPA had inhibitory effect on sludge unacclimatized by BPA. The acclimatized sludge has greater activity than unacclimatized sludge in BPA solution. Adsorption of BPA to sludge can be described by unlinear Freundlich isotherms, and the adsorption capacity is from 0.1736 to 0.6179 (mgBPA/g dry sludge) . Using GC-MS, 4-hydroxy-acetophenone is detected to be a biodegradation product, and the pathway of BPA is proposed in this paper.