Fouling characteristics of UF and RO membranes for reclamation of the wastewater from Iron and Steel Industry

Among the whole iron and steel-making processes, wastewaters from coke-making, blast furnace and steel-making contain relatively high organic contaminants due to direct using of raw materials like coal or iron ore. These wastewaters are pretreated by biological nutrients removal processes. On the other hand, wastewater from rolling-mill processes contains mainly inorganic contaminants. In this study, the fouling characteristics of membranes for reclamation of wastewaters from the processes using raw materials were analyzed through the pilot plant operation. The pilot plant was comprised of sand filter, activated carbon filter, ultrafiltration (UF) and reverse osmosis (RO) processes. Through the fouling effect analysis, algal and bacterial bio-foulings were dominant in the raw water tank and ultrafiltration membrane modules. This serious microbial contamination problem was greatly improved by using disinfectant and protection of sun-light by black painting. In the RO membranes, the alginate type biopolymer originated from microbial metabolism in the biological wastewater treatment process or contaminated membrane module was the main organic contaminant and inorganic contaminants exhibited conventional compound of calcium, silicon or aluminum.