连续运行高浓度猪粪推流式和全混式厌氧消化反应器性能研究

Comparison of Continuous Anaerobic Digestion of High-solid Pig Manure Between Plug-flow and Stirring Mixing Reactor

摘要:

高浓度厌氧消化可以减少沼液量,对于缓解工程中沼液出路难的问题有重要的现实意义。但是高浓度物料尤其是猪粪的厌氧分解可能存在搅拌传质差而导致的挥发性脂肪酸积累和产气效率低的问题。为此,本文采用理论上具有更高转化效率的推流式反应器开展122 d的连续运行试验,猪粪的进料总固体质量分数为15.6% ,水力停留时间50d,并在相同条件下与全混式工艺进行对比分析。试验结果表明,推流式反应器的挥发性固体(VS)去除率和甲烷产率分别达到65.1%和294mL/g(每克VS甲烷产率),显著高于全混式反应器(VS去除率51.2% ,甲烷产率233 mL/g(每克VS甲烷产率))。通过计算得出高浓度发酵比湿发酵可减少沼液产量68.7%。推流式和全混式反应器均未出现酸积累现象,体现出反应器长期运行的良好稳定性。本文证实在高含固猪粪厌氧发酵中,推流式反应器比全混式反应器具有更好的发酵性能,为提升高固体猪粪的发酵性能提供了技术参考。

Abstract:

Anaerobic digestion of high-solid manure can reduce the volume of digestate and benefit the biogas plant operation. However, the anaerobic digestion of high-solid manure, especially pig manure, may have problems such as accumulation of volatile fatty acids and low gas production efficiency caused by suppressed mass transfer and high viscosity. Therefore, a plug-flow reactor with theoretically higher efficiency was used to investigate the continuous anaerobic digestion performance of 122 days. The total solid concentration of the pig manure feed was 15. 6% and the hydraulic retention time was 50 days. A stirring mixing reactor under the same conditions was operated for comparison. The results obtained showed that the volatile solids (VS) removal efficiency and methane yield was 65.1% and 294mL/g in the plug-flow reactor. These results were significantly higher than those obtained in stirring mixing reactor, i. e. 51.2% and 233mL/g. It was calculated that high-concentration fermentation can reduce biogas slurry production by 68.7% compared with wet fermentation. During the prolonged operation, neither the plug-flow reactor nor the stirring mixed reactor exhibited acid accumulation. This indicated stable microbial communities and balanced metabolic pathways under continuous feeding. Both systems thus demonstrated excellent long-term operational stability and reliable performance. Conclusively, the research results can support the advanced performance in plug flow over stirring mixing reactor. High performance of anaerobic digestion of high-solid pig manure was thus feasible for industrial application.