Effects of alkalinity on membrane bioreactors for reject water treatment: Performance improvement, fouling mitigation and microbial structures.
Two submerged membrane bioreactors (MBRs) for reject water treatment were operated to investigate effects of sodium bicarbonate (SB) addition on enhancing process performance and mitigating membrane fouling. Results showed that SB addition enhanced average removal efficiencies of COD and NH4-N by 14.6% and 38.3%, respectively. With SB addition, the extracellular polymeric substances (EPS) content in activated sludge increased, but those in membrane foulants greatly decreased. Gel permeation chromatography analysis demonstrated that EPS in MBRs for reject water treatment had much larger molecular weight (MW) and broader MW distribution than those in MBRs for municipal wastewater treatment. The fouling mitigation by SB was attributed to a deprotonation mechanism reduced EPS adsorption on negatively charged membrane surfaces, and improvement of degradation efficiency of macromolecular organic matters. SB addition into MBRs for reject water treatment increased microbial abundance, enriched nitrifying bacteria, and converted predominant AOB genus from Nitrosomonas to Nitrosospira.
College of Environmental and Chemical Engineering, Shanghai University of Electric Power, 2588 Changyang Road, Shanghai 200090, China.
Dalong
D
Hu
College of Environmental and Chemical Engineering, Shanghai University of Electric Power, 2588 Changyang Road, Shanghai 200090, China. Electronic address: zhouzhen@shiep.edu.cn.
Zhen
Z
Zhou
College of Environmental and Chemical Engineering, Shanghai University of Electric Power, 2588 Changyang Road, Shanghai 200090, China.
Xuelian
X
Shen
Shanghai Chentou Wastewater Treatment Co., Ltd, Shanghai 201203, China.
Haijuan
H
Wei
College of Environmental and Chemical Engineering, Shanghai University of Electric Power, 2588 Changyang Road, Shanghai 200090, China.
Lu-Man
LM
Jiang
Shanghai Chentou Wastewater Treatment Co., Ltd, Shanghai 201203, China.
Yan
Y
Lv
D001419:Bacteria / Q000145:classification / Q000378:metabolism*; D057219:Biofouling / Q000517:prevention & control*; D019149:Bioreactors / Q000382:microbiology*; D002850:Chromatography, Gel; D008567:Membranes, Artificial; D011108:Polymers; D012722:Sewage / Q000382:microbiology*; D014865:Waste Disposal, Fluid / Q000379:methods; D062065:Wastewater; D014874:Water Pollutants, Chemical; D018508:Water Purification / Q000379:methods*
D008567:Membranes, Artificial; D011108:Polymers; D012722:Sewage; D062065:Wastewater; D014874:Water Pollutants, Chemical
Excitation–emission matrix; Extracellular polymeric substances; Fouling; Membrane bioreactor; Reject water