Characterization and potential of two different anaerobic mixed microflora for bioenergy recovery and decolorization of textile wastewater: Effect of C/N ratio, dye concentration and pH

A series of standardized activity experiments were conducted to investigate the effect of the C/N ratio, dye concentration, and pH on the performance of two mesophilic mixed cultures for bioenergy production and decolorization of textile wastewater. The results showed that the most significant factor was the C/N ratio with LogWorth value of 9.961. The maximum methane yield reached 13.18 ± 0.64 mmoL/g COD with chemical oxygen demand (COD) degradation and decolorization of 84.32 and 98%, respectively under digested sludge. The propionate and butyric acid/acetic acid ratio were significantly affected by C/N ratio and the results of C/N ratio were explained by changes in the soluble by-products. The dye concentration of 100 mg/L yielded the highest biogas production with a maximum decolorization percentage. The digested sludge showed better performance under all tested conditions compared to granular sludge. Analysis of the data showed that the best condition was observed and the bioreaction was optimized. [Display omitted] •The most significant factor was the C/N ratio with LogWorth value of 9.961.•The digested sludge showed better performance under all tested conditions.•The maximum methane yield reached 13.18 ± 0.64 mmoL/gCOD.•The influence of factors was explained by changes in soluble intermediate.