Nanofiltration membrane for recycling aqueous waste stream from Aluminosilicate manufacturing process

Abstract

Increasing scarcity of fresh water due to increased consumption newlineespecially in industry has led to a growing interest in water reclamation. newlineIndustrial activity results in release of several hazardous chemicals in to water newlinestream. These chemicals need to be recovered before the water can be reused to newlinemeet the regulatory requirement of zero discharge. In this work using nano newlinefiltration technique, sodium sulphate is recovered that has several industrial newlineapplications like in the manufacture aluminium silicate, detergents, Kraft paper, newlineglass, sodium salts, ceramic glazes, pharmaceuticals and dyeing of textile fibers. newlineThe wastewater stream from aluminium silicate industry for example newlinecontains sodium sulphate in the range of 1.0 gm/L to 5.0 gm/L whereas only a newlinemuch lower concentration of the sulphate in drinking water is enough to cause newlineacute diarrhea. Therefore, removal of the sulphate from wastewater streams newlinehaving even low concentration of the salt is desirable.. newlineThe conventional technique for salt recovery use evaporation followed newlineby crystallization which is uneconomical when salt concentration in the newlinewastewater is in the range of 1.0 gm/L to 5.0 gm/L. Membrane based newlinetechniques that not only give higher salt removal efficiencies but also allow newlinereuse of water in the process industry are gradually becoming attractive newlinealternative to the conventional method. newlineNF membrane with an average pore radius in the nanometer range newlinerequire a lower operating pressure compared to RO membrane and UF newlinemembrane. Lower energy consumption of NF results in overall economy in newlinewastewater treatment of several manufacturing industries. Research work on newlinerejection of several salts with NF membranes has been reported in literature. newlineThe results show that percentage salt rejection and permeate flux change with newlinethe type of NF membrane, its pore size, area, selectivity, porosity besides newlineoperating parameters such as temperature, feed pressure, pH of solution, type newlineand concentration of ions in the solution.