77 / 2023-06-28 19:53:40

Enhanced anaerobic digestion of food waste by thermal pretreatment and ethanol pre-fermentation: Performance and mechanism

Anaerobic fermentation,Methane production,Food waste,Pretreatment,Microbial community

Food waste (FW) is an ideal substrate for anaerobic digestion (AD), but the production efficiency, system stability and methane production potential of AD are influenced by the FW characteristics. Therefore, the FW is usually pretreated to achieve an efficient and stable AD process. Ethanol pre-fermentation (EP) can improve methane production efficiency and maintain AD system stability while promoting FW hydrolysis, but is more effective at high organic loading. Thermal pretreatment (TP) can substantially increase the content of soluble organic matter in FW, but with the risk of acid accumulation. Thus, combining TP and EP is expected to promote FW hydrolysis and improve methane production efficiency to a greater extent while maintaining AD system stability, but the mechanism of the effect on AD is not clear. This study revealed the mechanism of the effect of thermal pretreatment coupled with ethanol pre-fermentation (TP-EP) on the AD of FW. The results showed that thermal pretreatment coupled with ethanol pre-fermentation increased the degradation of SCOD (60.38%) and VFAs (76.27%) and increased the cumulative methane yield by 9.56-16.96%. TP-EP was enriched with a range of hydrolytic acid-producing bacteria, as well as methanogens Methanobacterium, Methanosarcina and Methanothrix. Therefore, thermal pretreatment coupled with ethanol prefermentation combined the advantages of both and promoted substrate hydrolysis and metabolism to a greater extent, while enhancing both aceticlastic and hydrogenotrophic methanogenic pathways.