Rapid Production of VFAs in Catalyzed Anaerobic Fermentation of Sludge

waste activated sludge;  anaerobic fermentation;  font-size: 10pt; ">volatile fatty acids; surfactant; ultrasound

The combined technology of ultrasonic pretreatment and adding surfactant was used to accelerate the production of volatile fatty acids (VFAs) in anaerobic fermentation of waste activated sludge.The effects of surfactant type and dosage, initial pH value, fermentation time, temperature and additional anaerobic bacteria on VFAs yield were explored by single factor experiments. When APG, JFC and TDP were used as surfactants, the acid yield of APG was the highest under the same conditions. When the dosage of surfactant was 0.8 g/600 mL, the initial pH value was 11, the fermentation time was 4 days, the fermentation temperature was 35 ℃ and no anaerobic bacteria was added, the maximum acid yield was 1 300 mg/L(in terms of COD) after ultrasonic pretreatment. When anaerobic bacteria were added, the maximum acid yield was 3 650 mg/L, which was three times higher than before, and the acetic acid content in VFAs was the largest.