Effect of Salinity on Enhancing Waste Activated Sludge Alkaline Fermentation at Different Temperatures

Abstract

Research Article Effect of Salinity on Enhancing Waste Activated Sludge Alkaline Fermentation at Different TemperaturesCarbon source shortage and waste sludge treatment are two problems facing sewage treatment plants. The purpose of this work was to investigate the feasibility of using salt (NaCl) to enhance the production of short-chain fatty acids (SCFAs) from waste sludge, reduce sludge production, and lower the operating cost. Four sodium chloride (NaCl) concentrations (0, 2, 15, and 25 g/L) and temperatures (20, 30, 35, and 40°C) were examined individually in batch-mode sludge fermentation systems. The results showed that NaCl promoted the release of soluble proteins and polysaccharides, enhanced hydrolysis acidification and SCFAs accumulation, suppressed the activity of coenzyme 420 and the growth of methanogens. The optimal condition of hydrolysis acidification was 15 g/L NaCl and 35°C, and the acidification was deteriorated at 25 g/L NaCl and 40°C. Compared with the blank test (0 g/L NaCl), the sludge reduction and SCFAs production increased by 22.12 and 21.21%, respectively. With regard to the alkali consumption per unit (1 mmol), the SCFAs production and sludge reduction was increased by 9.6 and 21.99%.