Co-treatment of potassium ferrate and peroxymonosulfate enhances the decomposition of the cotton straw and cow manure mixture

Abstract

Since there is high lignocellulose content in the cotton straw and cow manure mixture (MCC), the appropriate MCC pretreatment is important to promote the anaerobic digestion (AD) hydrolysis. This study mainly explored the effect of potassium ferrate (PF) and peroxymonosulfate (PMS) pretreatments on MCC decomposition. PMS + PF co-treatment showed a higher reduction of total solid and volatile solid than PF pretreatment and PMS pretreatment. Hydrolysis of treated MCC indicated that the PF pretreatment was more effective to the release of organics than the PMS pretreatment and the PMS + PF co-treatment. However, the PMS + PF co-treatment resulted in a higher lignin removal rate (40.4%–50.5%) than the PMS pretreatment (30.8%) and the PF pretreatment (21.4%). The PMS1 + PF2 co-treatment (molar ratio of 1:2) acquired the optimal lignin removal rate and the release of organics among the PMS + PF co-treatment with different dosing ratio. Potential mechanism was that PF reduction products activated PMS to produce free radicals (SO4−, OH), which attacked lignocellulosic components and promoted MCC decomposition. The PMS1 + PF2 co-treatment was deduced to be the optimal pretreatment method when considering MCC decomposition, biodegradability, and mass transfer in the bioreactor.