Clarification of saline textile dye waters using haloarchaeal aerobic sequential bioreactor system

Abstract

The presence of high concentration of salts in textile industrial effluent waters is a major hindrance to use of conventional activated sludge treatment. Hence, microbial processes functional at high concentration of salts are sought for. We devised an aerobic synthetic bioreactor using Halorubrum saccharovorum strain GUMFAS1 producing cellulase-free xylanase and Halococcus saccharolyticus strain GUFF70 producing xylanase-free cellulase, which requires and resist high concentrations of salt. Individual, whole cells of Halorubrum saccharovorum and Halococcus saccharolyticus gave a decolourization efficiency of 38 percent, 45 percent, 58 percent and 28 percent, 30 percent, 45 percent for methylene blue, malachite green and congo red, respectively. Decolourization could be increased to 40 percent, 50 percent and 60 percent for methylene blue, malachite green and congo red, respectively by using whole cells of both cultures in 1:1 (v/v). Spent media containing 16.4 U/ml of crude cellulase and 11.2 U/ml of crude xylanase could also decolourize the synthetic textile waters in addition to degrading cellulose and hemicelluloses. The mixture of whole cells and crude enzyme supernatants achieved 79 percent decolourization of mixture of synthetic textile dye waters in four days. Conclusively, the process devised by us is the first report on using archaeal microbes for decolourization of toxic dyes as well as degradation of cellulose and hemicellulose from saline synthetic textile waters.