Characterization of methionine decomposition during high solid sludge anaerobic digestion
This study is to investigate the relationship between the decrease in the volume fraction of hydrogen sulfide in biogas produced during high solid sludge thermal hydrolysis-anaerobic digestion and the inhibition of methionine decomposition.In this study,based on determining the distribution of intermediate products of sulfur-containing amino acids decomposition during high solid sludge anaerobic digestion,an inorganic salt medium with methionine as substrate was used to enrich microorganisms from high solid anaerobic digestion sludge.The microbial population structure after enrichment and the distribution of volatile organic sulfur during methionine decomposition were analyzed,and the inhibition by high solid sludge anaerobic digestion environment on methionine decomposition was discussed.The results show that the sulfur-containing products of high solid anaerobic decomposition of methionine include methyl mercaptan,dimethyl sulfide,dimethyl disulfide,and hydrogen sulfide.The accumulation of hydrogen sulfide volume fractions under conventional and high solid content during the anaerobic digestion batch test of methionine are about 2 417 × 10-6 and 1 418 × 10-6,respectively.The significant accumulation of methyl mercaptan and dimethyl sulfide indicates that the decrease in hydrogen sulfide production during high solid sludge anaerobic digestion can be caused by the accumulation of methionine's anaerobic decomposition intermediates.After the methionine enrichment experiment,the relative abundance of Pseudomonas is 26％.Methionine decomposition products included ammonia nitrogen,methyl mercaptan,and dimethyl disulfide.Among them,dimethyl disulfide reaches a plateau[267.7 × 10-6(volume fraction)]prior to methyl mercaptan[164.9 × 10-6(volume fraction)].It suggests that the conversion of methyl mercaptan to dimethyl disulfide is rapid in the early stage of the reaction,and the rate slows down in the later stage,and methyl mercaptan gradually starts to accumulate.The ammonia inhibition test shows that the dimethyl disulfide production rate decreases by 16.79％when the ammonia nitrogen concentration increases to 4 000 mg/L.It indicates that the high ammonia nitrogen condition in the high solid system can inhibit the conversion of methionine to dimethyl disulfide.The reduction of hydrogen sulfide volume fraction in biogas produced during high solid sludge anaerobic digestion is closely related to its anaerobic digestion environmental characteristics.
NETL
NSTL
万方数据
维普
