Study on optimization of co-digestion process parameters for enhancing biohydrogen production using response surface methodology

In the present study, batch anaerobic co-digestion experiment was conducted with dairy secondary clarifier waste activated sludge as substrate and anaerobic digested municipal waste activated sludge as seed sludge for enhancing biohydrogen rate. The statistical tools were used to study the effect of co-digestion process parameters (pH, seed sludge, temperature, and digestion time) on mixed liquor suspended soils (MLSS) reduction % and chemical oxygen demand (COD) solubilization %. The maximum of MLSS reduction and COD solubilization obtained at global optimal condition (pH 6, temperature 40°C, seed sludge 35 ml, and digestion time 30 days) determined, respectively, were 22.7 and 28.02%. Subsequently, the production data of cumulative biohydrogen were fitted with modified Gompertz equation and the biohydrogen kinetic parameters were determined.