The Effect Of Iron Shavings On The Synergistic Anaerobic Digestion Of Sludge And Kitchen Waste To Produce Acid And Methane

As the continuous improvement of living standards and environmental requirements higher and higher,municipal sludge production was increasing.Anaerobic co-digestion of food waste into municipal sludge was a kind of high efficient biological stabilization technology,which had the advantages of high methane production efficiency.However,there was a disadvantage that the anaerobic digestion system was easily acidified.Trivalent iron can promote the hydrolysis of organic matter,neutralize organic acids and reduce hydrogen sulfide in biogas.To enhance the capability of mixed organic solid waste anaerobic digestion on acid production and methanogenesis the rusted iron shavings were added to the anaerobic co-digestion system of municipal sludge containing food waste.To study the running stability,effects of rusted iron shavings on acid production,system stability and biogas production of digestion mixed organic solid waste were treated.Meanwhile compared to rusted iron shavings and clean iron shavings with copper wires.The results showed that increasing food waste has obvious benefits in improving methane production from anaerobic digestion of municipal sludge.The maximum daily CH₄ yield,specific CH₄ production potential and cumulative biogas production of the mixed group reached 11.84 mL·g^-1VS₀·d^-1,286.2 mL·g^-1VS_removedemoved and 525 mL·g^-1VS_removed,respectively.With the increase of the dosage of rusted iron shavings,the capability of producing acid and methane has enhanced wih the anaerobic digestion system of mixed solid waste.When the amount of rusted iron shavings was 25 g/L,VS removal rate reached 45.81%at the end of digestion.The highest VFA concent was 13694 mg/L on day 3 and the specific CH₄production potential was 408 mL·g^-1VS_removedemoved on day 35,which correspond to the increase in48.1%and 41.2%compared with those of the non-added group,respectively.The concent of hydrogen sulfide in biogas was reduced by 69.3%compared with those of the non-added group.The effect of rusted iron shavings was better than that of clean iron shavings and copper wires in enhancing anaerobic digestion system for acid production and methane production.The maximum VFA concent,daily CH₄ yield and specific CH₄ production potential of the mixed group with rusted iron shavings reached 11547 mg/L?16.4mL·g^-1VS₀·d^-11 and 362 mL·g^-1VS_removed,respectively.In conclusion,with the addition of rusted iron shavings,the VFA concent in the anaerobic co-digestion system of municipal sludge and food waste can be promoted,as a result,methane yield can be increased.