Comparative performance of four membrane-based treatment strategies for wastewater from explosives production

This study evaluates the performance of various configurations that involve ultrafiltration (UF), nanofiltration (NF), reverse osmosis (RO), ion exchange (IonEx), and fixed-bed filtration (FBF) for the treatment of wastewater from explosive production. The experiments were performed on a laboratory-scale dead-end membrane setup and ion exchange and fixed-bed filtration units. The performance of four treatment configurations was evaluated based on physicochemical analyses (COD, TOC, Pb (II), Na, NO₃ -N, pH, conductivity) and supported by membrane permeability monitoring and ecotoxicity tests with Vibrio fischeri and Lemna minor. The UF-NF-RO system demonstrated significant removal of pollutants, with COD, TOC, Pb(II), and Na reductions of 88.6 %, 63.3 %, 99.6 % and 91.1 %, respectively. However, despite of the high retention degrees, the effluent did not meet discharge standards. The UF-RO-RO configuration, which utilized a tighter UF membrane followed by two RO stages, achieved improved pollutant removal, but remained insufficient for regulatory compliance. The UF-RO-AnEx system showed high lead and sodium removal, but in the final effluent concentration of COD, TOC, and NO₃–N were above the allowed limits. The most effective configuration, FBF-IonEx-RO, employed fixed-bed filtration with sand, halloysite clay, and activated carbon before ion exchange and RO. This approach resulted in the nearly complete removal of Pb (II) and NO₃–N while significantly reducing COD and TOC concentrations, ultimately meeting discharge standards. Membrane permeability analysis revealed that scaling due to high conductivity had a greater impact on RO fouling than organic matter. Ecotoxicity tests using Lemna minor and Vibrio fischeri confirmed that the FBF-IonEx-RO configuration produced the least toxic effluent, demonstrating its potential as an effective wastewater treatment solution.