Study on Biological Decolorization of Textile Sewage in Kermanshah by Microbial Isolates from Environmental Samples

Nowadays, drug, pulping, textile and other industries are developed in most of the countries and their non save sewages makes many problems for environment. One of the most important dangerous sewage is pigmented sewage, which has complex structures such as azo compounds. In Iran one of the main sources of pigmented sewage is textile manufacturing. Hence, in order to remove colour of this sewage, the present study was conducted to evaluate potential of some bacteria for dye decolourising. To perform this investigation 30 samples from soil and 10 from sewage were collected. All bacteria with potential of decolorization were isolated and identified using biochemical tests. Out of seven different isolated bacteria three were Gram positive and four were Gram negative. Optimization of decolorization for all bacteria was carried out in second step with respect to evaluation of bacterial activity at different temperatures (25-45°C), pHs (5-9) and dye concentrations (0.01-0.04g/L). The results obtained indicated that the best temperature for all bacteria tested was 35°C, pH 8.0, and dye concentration 0.02 g/L. Therefore, decolorization of pigmented sewage for elimination of dangerous compounds could be possible using bacteria.