Cleaning fouled membranes using sludge enzymes

Abstract

Maintenance of membrane performance requires inevitable cleaning or "defouling" of fouled membranes. Membrane cleaning using sludge enzymes, was investigated by first characterising ostrich abattoir effluent for potential foulants, such as lipids, proteins and polysaccharides. Static fouling of polysulphone membranes using abattoir effluent was also performed. Biochemical analysis was performed using quantitative and qualitative methods for detection of proteins on fouled and defouled membranes. The ability of sulphidogenic proteases to remove proteins adsorbed on polysulphone membranes and capillary ultrafiltration membranes after static fouling, and ability to restore permeate fluxes and transmembrane pressure after dynamic fouling was also investigated. Permeate volumes were analysed for protein and amino acids concentrations. The abattoir effluent contained 553 μg/ml of lipid, 301 μg/ml of protein, 141 μg/ml of total carbohydrate, and 0.63 μg/ml of total reducing sugars. Static fouled membranes removed 23.4% of proteins. Defouling of dynamically fouled capillary ultrafiltration membranes using sulphidogenic proteases was successful at pH 10, 37°C, within 1 h. Sulphidogenic protease activity was 2.1 U/ml and Flux Recovery (FR%) was 64%.