Enhanced production of short-chain fatty acid from food waste stimulated by alkyl polyglycosides and its mechanism

- SCFAs production from food waste was greatly enhanced by the APG addition into anaerobic fermentation system.
- 0.2 g/g TS was the optimal APG dosage for SCFAs production.
- APG favored solubilization, hydrolysis and acidification but inhibited methanogenesis.
- The activities of key enzymes related with SCFAs production were improved by APG.

Short-chain fatty acids (SCFAs) are the valuable products derived from the anaerobic fermentation of organic solid waste. However, SCFAs yield was limited by the worse solubilization and hydrolysis of particulate organic matter, and rapid consumption of organic acid by methanogens. In this study, an efficient and green strategy, i.e. adding biosurfactant alkyl polyglycosides (APG) into anaerobic fermentation system, was applied to enhance SCFAs production from food waste. Experimental results showed that APG not only greatly improved SCFAs production but also shortened the fermentation time for the maximum SCFAs accumulation. The SCFAs yield at optimal APG dosage 0.2 g/g TS (total solid) reached 37.2 g/L, which was 3.1-fold of that in blank. Meanwhile, the time to accumulate the maximum SCFAs in the presence of APG was shortened from day 14 to day 6. The activities of key enzymes such as hydrolytic and acid-forming enzymes were greatly promoted due to the presence of APG. These results demonstrated that the enhanced mechanism of SCFAs production should be attributed to the acceleration of solubilization and hydrolysis, enhancement of acidification and inhibition of methanogenesis by APG.