Long-term performance of a submerged anaerobic membrane bioreactor treating malting wastewater at room temperature (23 ± 1 °C)

Abstract

Long-term (287 days) performance of a submerged anaerobic membrane bioreactor (AnMBR) treating malting wastewater at room temperature (23 ± 1 °C) condition was investigated. The effect of changing organic loading rate (1.33 ± 0.11–2.78 ± 0.20 kg COD/m³/d) on the treatment efficiency and the membrane performance was evaluated. The average chemical oxygen demand (COD) removal efficiency was between 87 ± 1% and 92 ± 3%, and the average biogas yield was 0.21 ± 0.07 L at STP/g CODremoved. At the end of Period 2, the membrane permeability recovery cleanings restored the permeability of the fouled membrane up to 97% of the virgin membrane permeability, and the experiment was continued using the cleaned membrane. The results of membrane permeability recovery tests, along with the scanning electron microscope (SEM) images and energy dispersive X-ray (EDX) spectra, at the end of the study, suggested that irreversible fouling had happened when the membrane was reused and worked for an extended duration. Furthermore, the influence of changing organic loading rate (OLR) on the microbial community was assessed using denaturing gradient gel electrophoresis (DGGE) of polymerase chain reaction (PCR) amplified 16S ribosomal ribonucleic acid gene (rDNA) regions. The results of cluster analysis revealed that the microbial community actively changed due to changes in the OLR.