Enhanced Anaerobic Digestion Of Food Waste With Trace Eiements And Analysis Of Microbial Community

Anaerobic digestion technology combines the advantages of waste treatment,energy recovery,and ecological virtuous cycle to become the mainstream technology of food waste（FW）treatment.A large number of studies have shown that the long-term operation of the anaerobic food waste under high load will always cause fatty acid（VFA）accumulation inhibition lead the system lost balance.The addition of trace elements（TEs）is an effective way to strengthen the anaerobic digestion of food waste.This research systematically investigated the influence of typical trace elements Fe,Co,Mo,Ni on the anaerobic digestion performance and microbial community of food waste under fixed load,stepwise increasing loads,and VFA inhibition.The results show that under low（2 g VS/L·day）and medium（4 g VS/L·day）load,the anaerobic system without TEs can maintain stability,but the gas production is significantly lower than the reactor with TEs;Under high load（6 g VS/L·day）,the system without TEs was suppressed by VFA and stopped gas production on Day 89,while the system with TEs was operating stably,with a methane production rate of 518.1 mL/g VSadded.Under stepwise increasing loads,the system without TEs（R5,R6）stopped gas production on Day 128 and 105,respectively,while the system with TEs（r5,r6）always maintained good performance.When R5 and R6 were inhibited by VFA,the relative abundance of Methanosaeta gradually decreased,while in r5 and r6,supplementation of TEs promoted the dominant growth of Methanosaeta,with abundances of 57.3%and 62.5%.At the initial stage of VFA inhibition,only pH adjustment did not restore the activity of methanogens significantly.The system stopped gas production on Day 139.With the addition of TEs and the combined strategy of pH adjustment and TEs addition,the system gradually returned to normal status and methane production rate reached 505.0,506.38 mL/g VSadded.In the mid-stage of VFA inhibition,the system that only adjusted pH or supplemented TEs stopped gas production on Day 133 and 129,respectively.Under the combined strategy of pH adjustment and TEs addition,the system performance gradually recovered normal condition and the anaerobic biochemical reaction reached equilibrium again.TEs played a key role in the activity recovery of methanogens under acid inhibition stress,and promoted the growth of aceticlastic methanogens Methanosaeta,which became the dominant strain again,and the aceticlastic pathway became the main methanogenic pathway.