Rgwo performances of submerged membrane bioreactor treating brewery wastewater: A laboratory study

Performances of submerged membrane bioreactor (SMBR) treating brewery wastewater were investigated in this study. With little variation of COD:TN:TP ratio (100:5:1) in influent, SMBR showed high removal efficiency (>90%) for both COD and NH4~+-N, and it also showed a strong resistive ability for shock organics loading rate, evidenced by no obvious fluctuation for COD in the effluent when the organics loading rate suddenly increased from 0.27 g/(gMLSS·d) to 0.54 g/(gMLSS·d). Comparatively different with the COD removal, TN and TP removal showed a strong correlation with the growth stage of the sludge in SMBR. When the sludge was in the multiplication stage, about 45% of TN was removed and an average removal efficiency of 30% for TP was also observed. However, when the activated sludge was in the steady stage, the removal efficiency for TN decreased to about 30%, whereas, the removal efficiency for TP was very low, and sometimes even below zero. The results of GC/MS indicated that the residual organic matters in the effluent were mainly alkyl hydrocarbon with high molecular weight, and coupling with the results of electroscopic scanning, it is speculated that biomass formed at external and internal membrane fibers played an important role for the removal of small organics.