Effect of zero-valent iron on methane production and phosphorus conversion during pig manure digestion
In order to solve the environmental pollution caused by organic matter and phosphorus in the biogas slurry of pig manure and to improve the generation of clean energy,the effects of zero-valent iron on methane pro-duction and phosphorus transformation were investigated during the anaerobic digestion of pig manure in this study.Techniques such as Fourier transform infrared spectrometer(FTIR),X-ray diffraction(XRD),and high-throughput sequencing were used to analyze the changes in methane production,phosphorus distribution and species,enzyme activities,and microbial community during anaerobic digestion.The results showed that zero-valent iron enriched acidifying bacteria such as Clostridun_sensu_stricto_1,Terripotobacter and Syntrophomonas,and the activities of protease and β-glucosidase were increased by 0.6 times and 2.4 times,respectively after adding zero-valent iron,and strengthened the hydrolytic acidification ability of the system.Moreover,zero-valent iron enriched Methanosaeta,which was help to enhance the activity of methanogen,and thus the methane production increased by 11.1%.In ad-dition,zero-valent iron also enriched phosphorus transforming microorganisms,such as Ruminofilibacter,WS6_Doj kabacteria etc.,which increased the activities of acid(alkali)phosphatase by about 26.3%,and promoted the conversion of organic phosphorus to inorganic phosphorus in the system.Moreover,zero-valent iron significantly increased the content of soluble Fe2+in the system,and improved the conversion of water-soluble phosphorus to Fe-bound phosphorus,which was finally fixed in the precipitate such as vivianite,and thus significantly reduced the concentration of total phosphorus in biogas slurry.The results provide a technical reference for improving methane production and phosphorus fixation in anaerobic digestion of pig manure.
pig manureanaerobic digestionzero-valent ironphosphorusmethane production
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