【作者】 张望；

【导师】 李秀金；

【作者基本信息】 北京化工大学 ， 环境工程， 2008， 硕士

【摘要】 用厌氧消化技术转化稻草获取清洁能源——生物气,是稻草生物质能源产业化的一条有效途径。为了实现稻草的高效能源转化,提高反应器的产气量和产气效率,同时简化发酵出料的处理和处置,本文提出用干法厌氧发酵对稻草进行中温消化生产生物气的研究,并为稻草的大规模生物气化提供指导。为探明不同干物质含量(即TS)对干法厌氧消化稻草秸秆试验的影响,将未经预处理的稻秸在中温生物反应器内进行厌氧干发酵,考察了TS浓度对稻秸发酵过程中的生物气产量、pH值、渗滤液COD及甲烷含量变化的影响。实验结果表明:TS20%固体浓度并加接种泥的反应器(R2)的累积产气量最大,达到2048L,其出料的半纤维素由28.2%降至18.3%,发酵液的pH值稳定在7.0～7.5。TS30%的干发酵(R3)在反应前期经历了很长的酸化期,产气量在后期才开始升高,生物气甲烷含量也更高,显示了高浓度固体干发酵产沼气的发展潜力。为探明粉煤灰和氢氧化钠预处理对稻草秸秆干发酵的影响,把经过6%氢氧化钠预处理的稻秸在中温生物反应器内进行干法厌氧发酵,研究了稻秸发酵过程中的生物气产量、pH值、渗滤液COD及甲烷含量的变化。结果表明TS20%、6%NaOH预处理并加粉煤灰的反应器(R2)的累积产气量最大,达到2777.1L,其出料的半纤维素由28.2%降至16.5%,发酵液的pH值稳定在7.0～7.5。TS20%加粉煤灰、未经预处理的R3在反应前期产气量平稳上升,56d后超过R2的日产气量,最终产气量只比R2低108.8L,但产气高峰晚于R2出现。与不加粉煤灰、不用碱预处理的R1相比,TS20%、粉煤灰和6%NaOH预处理的方案可以使总产气量提高47.6%以上。本研究结果表明:添加粉煤灰和6%NaOH预处理都可以明显改善稻草的厌氧消化产气性能,二者方法的耦合可以使总产气量比一般厌氧消化产气提高47.6%以上。该结论可为秸秆干法厌氧消化的工程应用提供了重要的设计依据。更多还原

【Abstract】 Anaerobic digestion is one of the feasibility technologies to utilize the rice straw, which can convert it into biogas. But there is little research has been conducted on anaerobic digestion of rice straw to biogas. Dry fermentation experiment is designed to improve the biodegradation efficiency and biogas production and to simplify the treatment process of the digested straw. In addition, it was showed that dry fermentation technology has both functional and economical advantages, and has great potential of application in China in the future for agriculture solid waste treatment and disposal.Dry anaerobic digestion technology with leachate circulated for untreated straw conversion to biogas was investigated in bioreactors at 35℃. Biogas production, pH, COD and methane content were tested. After 180 days of anaerobic digestion, it was observed that the Reactor 2 with TS 20% (R2) had the largest biogas production (2048L in total) while the biogas production were 1199.9L, 905.9L and 51.7L, respectively, in Reactor1, Reactor3 and Reactor4. The hemicelluloses of the digested straw in R2 decreased from 28.2% to 18.3%, and the pH value in zymotic fluid was stable at 7.0-7.5. The reactor R3 with TS 30% (R3) went on a long period of acidification before its biogas production turned higher, while its methane content was higher than that from R2. Leachate recirculation reduced the waste stabilization and was effective in enhancing methane gas production and improving leachate. The result indicated that sluge could be the inoculum source for anaerobic mesophilic digestion of the treatment of rice straw at dry condition. This study provided useful parameters for the design of large-scale dry anaerobic digester for straw conversion to biogas.On the other hand, it is found that co-disposal of refuse with coal ash and pre-treatment of alkali has many advantageous over conventional anaerobic digestion in terms of biogas production and volume reduction, due to the better adsorption and filtration roles with coal ash and pre-treatment of alkali. This result showed that coal ash and pre-treatment of alkali had some effectiveness on anaerobic digestion.Therefore, according to the results collected in this experiment, the best reactor is TS20%, with pre-treatment of alkali and addition of coal ash, which gas production increased 47.6%. This study could provide useful parameters for the design of field-scale dry fermentation for rice straw and coal ash disposal.更多还原