Polyethersulfone/fish-shrimp chitosan-based mixed matrix membrane for industrial wastewater treatment

In this study, chitosan (CH) was synthesized by processing of fish-shrimp solid waste (shell). It was utilized in the preparation of polyethersulfone (PES)-based mixed matrix membrane (M_x/CH_y) through the film casting method. The hydrophilicity of the membrane was modified by increasing the concentration of CH. The degree of deacetylation (DD%) of CH, analyzed using the acid-base titration method, was found to be 78%. The molecular weight cutoff (MWCO) of the membrane was analyzed using the polyethylene glycol rejection method. The surface properties such as mean pore size and hydrophilicity of the membrane were analyzed using a scanning electron microscope (SEM) micrograph and water contact angle meter. The membrane (M₁₈/CH_1.0) mean pore size and MWCO were 7.0 nm and 1.8 kDa, respectively, which is in the nanofiltration (NF) range. After cross-linking of CH with PES/PVP, hydrophilicity and porosity of the M₁₈/CH_1.0 increased. The feasibility of the membrane was tested for the treatment of industrial wastewater (iron and steel, distillery, and paper and pulp industry) by varying the feed pressure. The collected permeate through the M₁₈/CH_1.0 for all industrial wastewater was transparent. The M₁₈/CH_1.0 showed the removal efficiency as follows: turbidity, 65%; total dissolved solids (TDS), 86.6%; total suspended solids (TSS), 60.5%; chemical oxygen demand (COD), 99.5%; biochemical oxygen demand (BOD), 99.5%; and electrical conductivity (EC), 63.2% of distillery industry wastewater. In the case of steel and iron wastewater, it showed the removal efficiency for TDS, 48.3%; TSS, 65.3%; and EC, 42.2%. However, M₁₈/CH_1.0 removed the turbidity, 94.5%; TDS, 65.7%; TSS, 97.6%; and EC, 85.5% from the pulp and paper industry wastewater feed. The strong removal efficiency and resistance towards the fouling of the M₁₈/CH_1.0 make it a potential candidate for the application in the treatment of industrial wastewater.