Effect of organic loading rate on the performance of a submerged anaerobic membrane bioreactor (SAnMBR) for malting wastewater treatment and biogas production

Abstract

AbstractBACKGROUNDMost malting plants discharge their wastewater to the sewer system and have to pay high discharge fees. Malting wastewater is rich in nutrients and contains high soluble COD (mostly sugars and organic acids). Hence, it is suited for anaerobic treatment without nutrients addition and can produce biogas simultaneously. The main objective of this study was to investigate the treatability of malting wastewater in a submerged anaerobic membrane bioreactor (SAnMBR) and biogas production under mesophilic temperature conditions (36 ± 1 °C) and variable organic loading rates (OLRs).RESULTSAs the OLR was increased from 1.36 to 3.18 kg COD m‐3 d‐1, the COD removal efficiency decreased from 94.1 ± 2.5% to 90.2 ± 1.4%, the effluent COD increased from 283 ± 121 mg L‐1 to 506 ± 68 mg L‐1, and the biogas production yield decreased from 0.345 ± 0.007 to 0.308 ± 0.025 L g‐1 CODremoved. The BOD5 removal efficiency was consistently above 99%. Methane accounted for 70.9 ± 2.0% of the biogas. Membrane permeability measurements, scanning electron microscopy (SEM), and energy dispersive X‐ray (EDX) spectrometry indicated that the membrane fouling that occurred during operation of the SAnMBR could be removed by a series of physical and chemical cleaning steps.CONCLUSIONSMalting wastewater was successfully treated using a SAnMBR for the first time. The SAnMBR adapted quickly to both gradual and sudden changes in OLR. © 2017 Society of Chemical Industry