稻草中温干式厌氧发酵产甲烷的中试研究

A Pilot Study on Mesophilic Dry Anaerobic Digestion of Rice Straw

将未经预处理的稻秸,在中温生物反应器内进行厌氧干式发酵,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%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28.23%降至18.33%,发酵液的pH值稳定在7.0￣7.5。TS30%的干发酵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,并为秸秆的大规模生物气化提供了重要的设计依据。

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 （2 048 L in total） while the biogas production were 1 199.9 L, 905.9 L and 51.7 L, respectively, in Reactor 1, Reactor 3 and Reactor 4. The hemicelluloses of the digested straw in R2 decreased from 28.23% to 18.33%, 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 largescale dry anaerobic digester for straw conversion to biogas.