Enhanced production of biohydrogen from dairy waste activated sludge pre-treated using multi hydrolytic garbage enzyme complex and ultrasound-optimization

Fermentative hydrogen produced from activated sludge has received much attention among the scientific community. In the present study, optimized multi hydrolytic garbage enzyme complex (OGEC) produced from pre-consumer organic waste was used to hydrolysis dairy waste activated sludge (DWAS). Statistical optimization tools were used to determine the optimal environmental conditions for OGEC-DWAS pre-treatment and the models were evaluated. The result showed the maximum suspended solid reduction and solubilized chemical oxygen demand of 25.77% and 28.68% respectively were obtained at optimum conditions viz pH 6, temperature 40 degrees C, agitation speed 210 RPM and duration of pre-treatment 30 h. Further, to improve the solubilization of OGEC-DWAS, the effect of ultrasound on OGEC pre-treated sludge was investigated and results showed that 25 min of sonication time with power density of 0.6 W/ml improves the solubilization of OGEC-DWAS. Simultaneously cumulative biohydrogen production using pretreated DWAS through batch anaerobic digestion was studied and concluded that the maximum biohydrogen can be produced from combined OGEC-Ultrasound pretreated DWAS compared with raw sludge. This study helps to achieve an eco-friendly sustainable methodology to utilize WAS for biohydrogen production.