Synergistic effect of free nitrite acid integrated with biosurfactant alkyl polyglucose on sludge anaerobic fermentation

This study reports a new strategy, i.e. combination of free nitrite acid (FNA) and biosurfactant Alkyl polyglucose (APG), for the production of short chain fatty acids (SCFA) from sludge anaerobic fermentation. The results showed that when FNA concentration was 1.54 mg/L, the maximum yield of SCFA was 354.6 mg/g, which was significantly higher than that of FNA or APG alone. The combination of FNA and APG also shortened the optimal fermentation time to 5 d. Mechanism studies showed that FNA combined with APG can promote the sludge disintegration. By detecting the degradation of the simulated compounds in the synthetic water, it is found that the FNA combined with APG can synergistically promote sludge hydrolysis and acidification but seriously inhibit the methanogenesis process. The enzyme activity analysis was also consistent with the above experimental results. The combination of FNA and APG in this study provides a promising strategy for enhancing sludge anaerobic fermentation.