Biodegradation Studies of Non-Sterile Anaerobically Treated Distillery Spent Wash Using Aspergillus nidulans Isolated from Irrigation Site

The aim of this study was to evaluate the utility of isolated fungus in biodegradation of non-sterile molasses spent wash (MSW). The non-sterile MSW was used to check the biodegradation capabilities of isolated fungus in the presence of other contaminants. The irrigation site for culture isolation was selected to verify the presence of microbes that are suitable for MSW biodegradation. Three different fungi were isolated from the soil where MSW has been used for irrigation purpose. Higher decolorization was obtained with green color fungus, which was identified as Aspergillus nidulans Var. nidulans. The role of different carbon, nitrogen, pH, and MSW concentration was studied in biodegradation of non-sterile MSW. Higher decrease in chemical oxygen demand (COD) was obtained with sucrose, whereas galactose showed higher decolorization. Similarly, higher decrease in COD and color was obtained with sodium nitrate and ammonium sulphate respectively. However, higher decrease in COD and color was observed with yeast extract. Interestingly, significant increase in color was observed in the presence of urea. The pH optimization study has shown higher decrease in COD and color at pH 6.0, 8.0, and 10.0. Whereas, MSW concentration optimization study has shown higher reduction in COD (62 ± 1.8%) and color (79.6 ± 2.5%) at 12.5% concentration on 7 day. However, 74.0 ± 2.2% average decolorization was obtained for 12.5%, 25.0% and 37.5% MSW concentration. Results strongly suggest the suitability of isolated fungus in non-sterile MSW biodegradation at higher concentrations. Our findings may encourage the use of anaerobically digested MSW for irrigation.