Chen Guang-Yin, Zheng Zheng, Luo Yan, Zou Xing-Xing, Fang Cai-Xi
State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093, China.
Huan Jing Ke Xue. 2010 Sep;31(9):2208-13.
The biogas yields of rice straw during anaerobic digestion can be improved by alkaline pretreatment, while it increased the cost because of large amount of alkaline. In order to decrease the amount, 3 sets of experiments were performed using straw with alkaline treatment (pretreatment), digested straw with alkaline treatment (post-treatment) and straw digested directly (control). The results showed that cell wall of straw was destroyed by 5% NaOH treated for 48h, the COD (chemical oxygen demand), total nitrogen, NO(3-) -N and NH(4+) -N were increased from 2 311.11, 175.40, 5.02 and 117.82 mg/L to 10488.89, 417.84, 248.64 and 141.44 mg/L respectively. It suggested that not only lignocellulose but also some nitrogenous materials were destroyed or broken down by alkaline treatment. The lignin structure was destroyed through alkaline treatment that caused the decreased lignin, but the crystallinity index (C(r)I) of cellulose increased from 0.592 3 to 0.662 2. The results of anaerobic digestion showed that the total solid of straw decreased 50.47% after anaerobic digestion treatment leading to less workload and only 50% alkaline used. However, the biogas yield of post-treatment and pretreatment were 382.32 mL/g of TS(added) and 375.84 mL/g of TS(added). Lignin content of control increased while decreased in pretreatment and post-treatment. After anaerobic digestion, crystalline of cellulose was destroyed significantly, and crystalline and amorphous of post-treatment were destroyed more severely than that of pretreatment. From all those mentioned above, post-treatment of straw with alkaline was economical and feasible for biogas production.
通过碱性预处理可以提高稻草在厌氧消化过程中的沼气产量，但由于大量使用碱，这增加了成本。为了减少碱的用量，进行了3组实验，分别使用经过碱性处理的稻草（预处理）、经过碱性处理的消化稻草（后处理）和直接消化的稻草（对照）。结果表明，用5%的NaOH处理48h可破坏稻草的细胞壁，化学需氧量（COD）、总氮、NO(3-) -N和NH(4+) -N分别从2311.11、175.40、5.02和117.82mg/L增加到10488.89、417.84、248.64和141.44mg/L。这表明碱性处理不仅破坏了木质纤维素，还分解了一些含氮物质。碱性处理破坏了木质素结构，导致木质素含量降低，但纤维素的结晶度指数（C(r)I）从0.592 3增加到0.662 2。厌氧消化结果表明，稻草经过厌氧消化处理后总固体减少了50.47%，工作量减少，碱用量仅为原来的50%。然而，后处理和预处理的沼气产量分别为382.32mL/g TS（添加量）和375.84mL/g TS（添加量）。对照中木质素含量增加，而预处理和后处理中木质素含量降低。厌氧消化后，纤维素的结晶度被显著破坏，后处理中纤维素的结晶区和非结晶区比预处理中破坏得更严重。综上所述，对稻草进行碱性后处理用于沼气生产经济可行。
