Optimization of Protein Extraction from the Low Organic Residual Municipal Sludge Waste

In this study, municipal sludge waste was used for protein extraction. Two pretreatment ways such as acid and alkaline hydrolysis were compared and the alkaline hydrolysis method was selected as the better way for protein extraction from the residual sludge. In order to obtain the optimal condition for protein extraction, the factors such as NaOH concentration, NaOH solution volume and pretreatment period were selected and optimized by response surface methodology, and the optimal condition for protein extraction was obtained: NaOH concentration was 3.85 mol/l , 24.0 g wet municipal sludge waste was added in 1 L of water, and the pretreatment period was of 12.16 h at 50 °C. Under the optimal extraction condition, the protein extraction yield could reach 5923±107 μg/g sludge, which were 2.07 folds than the initial production pretreated by NaOH.