Abstract
Bisphenol A (BPA) is an endocrine disruptor that is difficult to completely remove from wastewater by conventional biological methods. Increased post-treatment BPA removal with ceramic membranes is worth investigating because of these membranes’ mechanical and chemical stability and lifespan. To determine the effectiveness of ceramic membranes for post-treatment of biologically treated BPA-contaminated wastewater, microfiltration (MF) and nanofiltration (NF) were conducted. Both processes removed BPA completely at an initial BPA concentration of 0.3 ± 0.14 mg/L. Increased concentration of 0.7 ± 0.29 mg/L decreased BPA removal. MF removed at least 24 % of BPA, presumably because BPA was adsorbed on particulate matter, which was retained by the membrane, or adsorbed on its surface. NF removed up to thrice more BPA. MF and NF completely removed suspended solids and 40–60 % COD. Filtration capacity decreased with time due to fouling but did not depend on initial BPA concentration. BPA concentrations in municipal wastewater are typically lower than the lowest concentration tested, where MF completely removed BPA. Hence, MF ceramic membranes appear a promising solution for post-treatment of BPA-containing wastewater. MF can be used at a much lower transmembrane pressure than NF, requiring less energy to pump wastewater through the membrane, thus reducing costs.
Highlights
Bisphenol A (2,2-bis-4-hydroxyphenylpropane, BPA) is a widely used xeno-estrogen, mainly in the production of polycarbonate plastics and epoxy resins
The effluent from the reactor with immobilized biomass was post-treated by membrane filtration because of high concentrations of COD, suspended solids and BPA
Two kinds of filtration were selected to differentiate the amount of BPA adsorbed on suspended solids, which would be removed by MF, and the amount of BPA in soluble forms, which would be removed by NF in addition to the BPA adsorbed on suspended solids
Summary
Bisphenol A (2,2-bis-4-hydroxyphenylpropane, BPA) is a widely used xeno-estrogen, mainly in the production of polycarbonate plastics and epoxy resins. It is considered an environmental pollutant with comparatively high biological activity and is classified as an endocrine disrupting compound (EDC). Residual BPA is present in the effluents from municipal wastewater treatment plants in concentrations ranging from 0.01 lg/L (Nasu et al 2001) to 86.0 lg/L (Kasprzyk-Hordern et al 2009). This is a cause for concern because BPA is estrogenic at concentrations below 1 ng/L (Tanaka et al 2000)
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