碳氮比对稻秸厌氧发酵过程的影响

Effect of C/N on Anaerobic Digestion of Rice Straw

在实验室条件下,考察了C/N对稻秸厌氧发酵过程的影响,重点研究了不同C/N对稻秸厌氧发酵前后氮素转化的影响,实验设置初始C/N分别为15∶1(T1),25∶1(T2),35∶1(T3)和45∶1(T4)4个处理.结果表明,C/N对稻秸厌氧发酵产气的影响较大,C/N太高发酵初期会出现酸化现象,以C/N 25∶1的产气效果最好,TS产气量为286.82 mL.g-1;不同C/N对甲烷含量的影响不大,各处理平均甲烷含量均在55%左右;厌氧发酵后,稻秸中有机物被大量分解,VS,纤维素和半纤维素含量大幅降低,纤维素结晶区受到较大破坏,木质素相对被浓缩,FTIR和XRD的结果与常规分析的结果一致;厌氧发酵过程中,氮素的损失较大,T1,T2,T3和T4的氮素损失率分别为43.97%,42.94%,33.71%和32.34%;氮素主要流向沼液中,但随着初始C/N从15∶1提高到45∶1,保留在沼渣中氮素的比例从29.77%增加到42.86%;厌氧发酵后厌氧系统中氮素以铵态氮和有机氮为主,随着C/N增加,总氮中铵态氮的比重降低,有机氮的比重增加,硝态氮无论是在沼渣还是沼液中含量均不高。

Effect of C/N on anaerobic digestion of rice straw and nitrogen transformation during the process were studied. Four treatments with tile initial C/N ratio of 15：1 （T1）, 25：1 （T2）, 35：1 （T3） and 45：1 （T4） were designed. The re- sults indicated that, biogas production of rice straw was influenced significantly by initial C/N ratio; too higher initial C/N ratio was adverse to biogas production; the highest TS biogas yield of 286.82 mL · g^-1 was obtained at initial C/N ratio of 25： 1. Average methane content of all treatments was about 55%. After anaerobic digestion, much organic matter and crys- talline of cellulose in rice straw were decomposed, content of volatile solid, cellulose and hemi-cellulose were decreased largely, and percentage of lignin was increased, Milch was consistent to the results of physic-chemical analysis. Much ni- trogen was lost during anaerobic digestion. The nitrogen loss rate of T1, T2, 33 and T4 were 43.97%, 42.94%, 33.71% and 32.34%, respectively. Much nitrogen went into fermentation slurry after anaerobic digestion, but amount of nitrogen remained in fermentation residue increased from 29.77% to 42.86% with the initial C/N ratio increased from 15：1 to 45： 1. The major nitrogen forms in anaerobic system was ammonium nitrogen and organic nitrogen, and the rate of ammoni- um nitrogen to total nitrogen decreased and the rate of organic nitrogen to total nitrogen increased with the increase of initial C/N ratio. Content of nitrate in anaerobic system was low.