The synergistic effect of potassium ferrate and peroxymonosulfate application on biogas production and shaping microbial community during anaerobic co-digestion of a cow manure-cotton straw mixture

Anaerobic co-digestion of a cow manure-cotton straw mixture (CCM) has been shown to promote methanogenesis, but the recalcitrant crystal structure of organic polymers in CCM hinders its hydrolysis during anaerobic digestion (AD). Here, the efficacy of different pretreatment methods based on potassium ferrate (PF) and peroxymonosulfate (PMS) was evaluated to facilitate CCM decomposition and methanogenesis during AD. The maximum lignocellulosic removal rate (62.5%), the highest volatile fatty acids (VFAs) (7769.6 mg/L), and cumulative methane yield (109.4 mL CH₄/g VS) were both achieved in PF-pretreated samples after the digestion process. The dominant bacterial populations in PF-pretreated CCM were affiliated with Sideroxydans, Herbinix, Clostridium, and Smithella, which played an important role in the hydrolysis and acidification of CCM. The enrichment of Methanosarcina and Methanobacterium and highly-effective acidogenesis might account for the highest methane yield in the PF-pretreated group.