Journal of Biotechnology & Biomaterials
Open Access

Abstract

An example of an endocrine disrupting micro pollutant that can be biologically removed from wastewater by sorption and biodegradation is bisphenol A (BPA). When biologically removing BPA, granular biomass allows a high concentration of active microorganisms per unit volume of the reactor and a high absorptive capacity due to the high content of extracellular polymers in its structure. To determine how the concentration of BPA in wastewater influences the effectiveness of carbon compounds (COD) removal, biomass growth (Y) and granule diameter, five constantly aerated reactors with granules (GSBRs) were operated at an HRT of 16 h. BPA concentrations in the synthetic wastewater were 0 mg/L in the control reactor, and 2, 4, 6 and 12 mg/L in the remaining four reactors. The overall COD concentration in the influent to the reactors, including BPA concentration, was about 400 mg COD/L; ammonium concentration was about 50 mg N-NH4/L. At least 200 cycles were performed in all reactors. Biomass concentration in the GSBRs ranged from 9268±2266 mg TSS/L at a BPA concentration of 2 mg/L to 10448±2266 mg TSS/L at a BPA concentration of 12 mg/L. The diameter of the granules increased with increasing BPA concentration in the influent. At the two highest BPA concentrations, granules with the diameter over 2 mm dominated in the biomass. These granules accounted for 24% and 37% of the total biomass, respectively at the BPA concentrations of 6 mg/L and 12 mg/L in the influent. This greater size may have allowed for better retention of biomass, thus slightly increasing the biomass concentration. Regardless of BPA concentrations in wastewater, COD was removed within the first 1-1.5 h of the GSBRs cycle. The effectiveness of COD removal by the aerobic granular sludge ranged from 75.1±17.8% at a concentration of 4mg BPA/L to 91.4±7.7% at a concentration 12 mg BPA/L, which may indicate that the latter concentration of BPA in the influent increased the effectiveness of COD removal. Y was lowest (0.28g TSS/g COD) at concentrations of 2 and 12 mg BPA/L and highest (0.42g TSS/g COD) at 6 mg BPA/L, as compared to 0.38g TS/g COD in the control reactor.

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