Effects of chemical cleaning on RO membrane inorganic, organic and microbial foulant removal in a full-scale plant for municipal wastewater reclamation.
Of all of the strategies for controlling reverse osmosis (RO) membrane fouling, chemical cleaning is indispensable. To study the effects of chemical cleaning on membrane foulant removal, a comparative analysis of RO membranes before and after common alkaline and acid cleaning was conducted by dissecting lead and terminal RO membranes in a full-scale municipal wastewater reclamation plant. Most foulants on the membranes were removed by chemical cleaning processes. Calcium was the major inorganic component of the foulants because of its highest concentration in the feed water. Aluminum and iron were also abundant elements on the membranes due to their high deposition ratios and low removal efficiencies. Hydrophilic neutrals (HIN) and hydrophobic neutrals (HON) were the two largest dissolved organic matter (DOM) fractions on the membranes before cleaning. HIN and hydrophilic acids (HIA) were not effectively removed. Chemical cleaning removed 94% and 90% of the total bacteria on the lead and tail membranes and considerably changed the structure of the microbial communities. Bacteria excessively producing extracellular polymeric substance (EPS), such as Pseudomonas and Zoogloea, were much more resistant to the chemical cleaning process. After cleaning, the membrane microbial community structures were more similar to those in the feed water than the structures on the membranes before cleaning. These results shed light on the effects of cleaning in a full-scale RO plant, improves our understanding of the removal of foulants and provides potential research directions for cleaning methods and RO pretreatment processes.
Environmental Simulation and Pollution Control State Key Joint Laboratory, State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), School of Environment, Tsinghua University, Beijing 100084, PR China. Electronic address: yt1987728@126.com.
Tong
T
Yu
Environmental Simulation and Pollution Control State Key Joint Laboratory, State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), School of Environment, Tsinghua University, Beijing 100084, PR China.
Lu
L
Meng
Beijing Boda Water Co., Ltd, Beijing 100176, PR China.
Qing-Bo
QB
Zhao
Beijing Boda Water Co., Ltd, Beijing 100176, PR China.
Ye
Y
Shi
Environmental Simulation and Pollution Control State Key Joint Laboratory, State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), School of Environment, Tsinghua University, Beijing 100084, PR China; Shenzhen Environmental Science and New Energy Technology Engineering Laboratory, Tsinghua-Berkeley Shenzhen Institute, Shenzhen 518055, PR China.
Hong-Ying
HY
Hu
Environmental Simulation and Pollution Control State Key Joint Laboratory, State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), School of Environment, Tsinghua University, Beijing 100084, PR China. Electronic address: luyun@tsinghua.edu.cn.
Yun
Y
Lu
D008567:Membranes, Artificial; D009995:Osmosis; D014865:Waste Disposal, Fluid; D062065:Wastewater / Q000737:chemistry*; D018508:Water Purification
D008567:Membranes, Artificial; D062065:Wastewater
Chemical cleaning; Membrane fouling; Microbial community; Reverse osmosis (RO); Wastewater reclamation