Evaluation of long-term operational and treatment performance of a high-biomass submerged anaerobic membrane bioreactor treating abattoir wastewater

Abstract

Although anaerobic membrane bioreactors (AnMBR) are widely used in high-strength wastewater treatment and resource recovery, membrane operational performance and membrane fouling control remain critical issues. In this study, the operational and treatment performance of a high-biomass (18 ≤ MLSS (g/L) ≤ 35) submerged anaerobic membrane bioreactor (HBSAnMBR) was assessed at organic loading rates (OLR) of 1.05–5 kg-COD/m3/d to treat abattoir wastewater (AWW). The correlation between kinetic parameters representing biomass yield and extracellular polymeric substances (EPS) was thoroughly investigated using mathematical models. It was found that the yield of biomass and EPS correlated positively with applied OLR and were found in the range of 0.13–0.31 g-MLSS/g-COD and 0.00001–0.000013 g-EPS/g-MLSS, respectively. This study also systematically examined the cake layer fouling mechanisms of HBSAnMBR due to EPS and the influence of soluble microbial products (SMP) on membrane pore blocking. OLR above 4 kg-COD/m3/d negatively affected the performance in terms of TMP, filtration resistance, EPS/SMP production, and COD removal suggesting that HBSAnMBR can be operated sustainably at OLR 4 kg-COD/m3/d. The membrane autopsy analyses and foulant characterization found that cake layer foulants were primarily composed of polysaccharides and proteins, while the membrane did not experience pore-blocking. At the same time, sodium, phosphorous, and calcium triggered inorganic fouling. The efficient treatment of abattoir wastewater showed that the HBSAnMBR system could be applied to treat trade wastewater containing high-organic content.