Effect of hydraulic retention time on biological nutrients removal in an anaerobic membrane bioreactor treating low-strength drain wastewater

Abstract

This work compares the nutrients removal efficiency of an anaerobic membrane bioreactor (AnMBR) treating low-strength drain wastewater (total chemical oxygen demand CODt of 157.09 ± 34.83 mg/L) at two different hydraulic retention times (HRTs). Because nutrients removal is poor in anaerobic systems, longer HRTs of 4 days and 3 days were opted for in this study. AnMBR performance was superior at 3 day HRT with removal efficiencies of 53.32 ± 4.83 % (CODt), 88.60 ± 19.04 % (ammonia-nitrogen, NH4+-N), and 63.65 ± 4.90 % (phosphate, PO43−) with higher permeate flux of around 6.6 L/m2 h. The possible reason for achieving better nutrients removal at 3 day HRT could be enough food and adequate contact time experienced by the microorganisms. Therefore, longer yet sufficient HRT can be an approach for improved nutrients removal in an AnMBR treating low-strength wastewater.