Electrocoagulation pretreatment of pulp and paper wastewater for low pressure reverse osmosis membrane fouling control

• Published in: Environmental science and pollution research international 2022-05, Vol.29 (24), p.36897-36910
• Main Authors: Gong, Chenhao, Ren, Xiaojing, Zhang, Zhongguo, Sun, Yuwei, Huang, Haiou
• Format: Article
• Language: English
• Subjects: Ammonia; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Carboxylic acids; Earth and Environmental Science; Ecotoxicology; Electrocoagulation; Environment; Environmental Chemistry; Environmental Health; Environmental Pollutants; Environmental science; Feedwater; Fluorescence; Fouling; Fouling control; Fourier transforms; Fulvic acids; Functional groups; Humic acids; Infrared spectroscopy; Low pressure; Membrane processes; Membranes; Membranes, Artificial; Osmosis; Out of plane bending; Pollutants; Pretreatment; Pulp; Pulp & paper industry; Research Article; Reverse osmosis; Scientific imaging; Spectrometry; Waste Water - chemistry; Waste Water Technology; Wastewater; Water Management; Water Pollution Control; Water Purification - methods; Water reuse
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-021-18045-6

Low pressure reverse osmosis (LPRO) has been increasingly used in advanced treatment of pulp and paper wastewater (PPWW) for the purpose of water reuse. However, membrane fouling is a major problem encountered by full-scale RO systems due to the organic and inorganic contents of the feedwater. Electrocoagulation (EC) as an effective treatment for foulants removal can be applied in pre-filtration. Therefore, the LPRO membrane fouling mechanism and the membrane fouling control performance by EC treatment were investigated in this study. EC pretreatment could reduce the membrane fouling and improve the membrane flux by 31%, by effectively removing and/or decomposing the organic pollutants in PPWW. Fluorescent spectrometry analyses of the feedwater and the permeate revealed that humic acid-like and fulvic acid-like organics in PPWW were the major foulants for the LPRO membranes. Fourier transformation infrared spectrometry results confirmed that the organic foulants contained benzoic rings and carboxylic groups, which were typical for organic substances. EC effectively removed organic pollutants containing functional groups such as carboxylic acid COH out-of-plane bending, olefin (trans), and NH 3 + symmetrical angle-changing. Moreover, the extended Derjaguin-Landau-Verwey-Overbeek model suggested that the membrane filtered 30-min EC-treated PPWW had the strong repulsion force to foulants due to the higher cohesion energy (12.1 mJ/m 2 ) and the lower critical load, which theoretically explained the reason of EC pretreatment on membrane fouling control.