Extremely fouling resistant zwitterionic copolymer membranes with ∼ 1 nm pore size for treating municipal, oily and textile wastewater streams

In this study, we document the performance of novel zwitterionic copolymer membranes with a molecular weight cut-off (MWCO) of around 1 kDa in treating municipal and industrial wastewater streams. These membranes were prepared by forming selective layers of self-assembling zwitterionic amphiphilic random copolymers on porous supports by a simple coating method. In single-and mixed-solute fouling tests with common components of effluent organic matter in municipal wastewater feeds (polysaccharides, natural organic matter, and fatty acids), these membranes showed complete resistance to irreversible fouling. The same excellent fouling resistance was also observed with oil emulsions common in industrial wastewater. One membrane showed no decline in flux even during the 7-day dead-end filtration of an oil emulsion, which is an unprecedented degree of fouling resistance. Both membranes also exhibited no irreversible flux decline after filtering real wastewater samples from a textile dyeing plant in Turkey. High rejections of dyes and colored substances were achieved, while salts were allowed to permeate. This allows for low pressure operation. The effluent can potentially be reused with minimal post-treatment. Thus, zwitterionic copolymer membranes are very promising for municipal and industrial wastewater treatment and reuse.