不同氮源对麦秆厌氧消化过程的影响

在中温(35±1)℃]条件下,采用批式发酵方式,研究了不同氮源对麦秆厌氧消化过程的影响.结果表明,不添加氮源时,麦秆挥发性固体(VS)产气量为323.97mL/g,甲烷含量为64.38%;厌氧发酵后发酵液中各形态氮含量均大幅增加,发酵液中的氮以铵态氮和有机氮为主;发酵后的麦秆中木质素含量增加,纤维素结晶区受到一定程度的破坏.添加氮源提高了微生物的活性,产气速率大幅提高,VS产气量提高了35.37%~50.20%,但对甲烷含量的影响不大.除硝酸钾外,添加氮源的各处理发酵液中均以铵态氮为主,占总氮的70%以上,添加硝酸钾的处理最低,仅为54.60%,均远高于对照的38.49%.添加氮源及不同氮源对发酵液中硝态氮含量的影响不大;添加氮源促进了微生物对麦秆中纤维素和半纤维的破坏,但对纤维素结晶区的影响不大.在各种氮源中,以添加尿素的效果最好.

Effects of nitrogen sources on anaerobic digestion process of wheat straw

Effects of nitrogen sources on anaerobic digestion process of wheat straw were investigated by batch model at (35±1)℃. The results indicated that, the biogas productivity of wheat straw without nitrogen recourse was slow and the biogas yield was 323.97mL/g VS with 64.38% of methane content. Various forms of nitrogen and total nitrogen increased dramatically and ammonium nitrogen and organic nitrogen were dominant after anaerobic digestion. Lignin content increased with the degradation of cellulose, semi-cellulose and other organic matter. Addition of nitrogen sources improved the biodegradability of wheat straw and the biogas yield by 35.37%~50.20%, but didn’t affect the methane content. Compared with control, ammonium nitrogen was the mainly form in the fermentation liquid of all treatments after anaerobic digestion and the ratio of ammonium nitrogen to total nitrogen were up to 70% except potassium nitrate (only 54.60%). There was no significant difference of nitrate nitrogen content of fermentation liquid between nitrogen sources added and control. With nitrogen sources added, the decomposition of cellulose and semi-cellulose was improved, but didn’t affect the destruction of crystalline of cellulose. The best efficacy to anaerobic digestion of wheat straw was obtained by adding urea.