Promoting the production of methane on the co-digestion of food waste and sewage sludge by aerobic pre-treatment

In this study, methane (CH₄) production performance on the co-digestion of food waste (FW) and sewage sludge (SS) was compared under non-pretreatment and 6 days aerobic pre-treatment. The results showed that, compared with the non-aerobic group, the CH₄ productivity increased by nearly 60% through aerobic pretreatment. More ammonium was obtained after pre-aeration, providing a suitable growth environment for methanogens. After the aerobic pretreatment, proteins and carbohydrates converted into solute protein and carbohydrate, which could be easily consumed by microorganisms, concentrations of solute protein and carbohydrate were 350 and 667 mg/L in R2 and Pre-R2, respectively. At the same time, aerobic pretreatment affected the distribution of microbial community in the system. In the stable stage of Pre-R2, Methanosarcina as acetate-utilizing methanogen, became the dominant in the reactor, whose abundance was over 93%. It meant after the aerobic pretreatment, the main pathway for methanogenesis was acetotrophy. This study revealed that pre-aeration is a simple and desirable strategy for improving the CH₄ productivity on the co-digestion of FW and SS.