Article ID Journal Published Year Pages File Type
642414 Separation and Purification Technology 2012 9 Pages PDF
Abstract

With the recent emergence of estrogenic contaminants as reclaimed wastewater quality issue, our study has investigated the removal of bisphenol-A (BPA) using a submerged membrane bioreactor. Experiments were performed at initial BPA concentrations ranging from 1.0 to 15 mg/L. A very low sludge mineralization occurred in the bioreactor (with a VSS/TSS ratio around 0.8–0.9), irrespective of the variation of biomass concentration and a long retention time of solids. The specific oxygen uptake rate values recorded did not reveal any significant change in the microbial respiratory activity in the absence (2.00 mg O2/g VSS h) and in the presence (1.4 mg O2/g VSS h) of BPA in the synthetic effluent. The performance of the bioreactor in terms of COD removal remained constant and reached 99% irrespective of the hydraulic retention time imposed (3–6 h), whereas 66–99% of COD removal was recorded while using conventional activated sludge system. The limit of the toxicity (21.6 g BPA/m3/d) determined for the bioreactor membrane system was higher than that recorded for the conventional activated sludge (2.5 g BPA/m3/d). BPA was effectively removed in the membrane bioreactor (abatement ⩾98% was reached) due to adsorption and biodegradation/transformation processes. Residual BPA concentrations recorded in the mixed liquor remained low (0.017–0.004 mg/L), when the raw wastewater contained a concentration of 1.0 mg BPA/L. This indicates that BPA was not accumulated in the membrane bioreactor, but bacteria oxidized it. Likewise, the membrane bioreactor was found to be effective in removing ammonia–nitrogen (>99% of N–NH4 removed), whereas 61% of phosphate (P–PO4) could be simultaneously removed. The membrane bioreactor was a total barrier for total suspended solid and turbidity was effectively removed (residual turbidity was lower than 1.0 NTU).

► COD removal reached 99% for 0.3–1.0 kg COD/kg VSS/d by using SMBR system. ► By comparison, 66–99% of COD removal was recorded while using CASR. ► The limit of the toxicity of BPA determined for the SMBR was 21.6 g BPA/m3/d. ► By comparison, a limit of the toxicity for CASR was 2.5 g BPA/m3/d. ► BPA was effectively removed from SMBR and an abatement ⩾98% was reached.

Related Topics
Physical Sciences and Engineering Chemical Engineering Filtration and Separation
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