Many of the biogas plants in China run at the lower range of mesophilic conditions and low organic loading rates. The objective of this study was to evaluate the performance (methane yield, production of volatile fatty acid (VFA) and total inorganic carbon (TIC)) of completely stirred tank reactor which was fed with pig manure semi-continuously at different temperature (20, 28, 38°C) and organic loading rates (0.3-4.3 kg/(m3d)). The results showed that the start-up phase last for a long time at 20 °C with low methane yield at organic loading rate (OLR) of 0.3 kg/(m3d) and pH was kept stable with additional NaHCO3 at OLR of 1.3 kg/(m3-d). There was no significant difference on methane yield between 28 °C and 38°C at each phase of this experiment. However, at 28°C, VFA accumulation was observed at OLR of 3.3 and 4.3 kg/(m -d) and the VFA/TIC ratio was 0.4 and 0.6, respectively. For a biogas plant running with low organic loading rate, it seemed to be an energy input saving way if the operation temperature was kept at 28 °C. The results of this study are valuable for the management of agricultural biogas plants.%为提高畜禽养殖场沼气工程能源利用效率,降低工程运行成本.该文通过全混式半连续试验,以猪粪为发酵原料,研究不同温度(20、28、38℃)和有机负荷(0.3、1.3、2.3、3.3、4.3 kg/(m3·d))条件下,甲烷产率、挥发性脂肪酸(volatile fatty acid,VFA)及总无机碳(total inorganic carbon,TIC)的变化特征.结果表明:20℃条件下,反应器启动缓慢,甲烷产率低.当有机负荷增加全1.3 kg/(m3·d)以上时,反应器运行不稳定,需外加NaHCO3调节pH值；在28℃与38℃条件下,各有机负荷甲烷产率无明显差异,但是在较高有机负荷3.3和4.3 kg/(m3·d)下运行时,28℃条件下产生挥发性脂肪酸积累的现象,系统缓冲能力缺乏,VFA/TIC值分别达到0.4和0.6.当实际沼气工程低负荷率运行时,可选择28℃作为发酵温度,以达到节省能源、提高沼气工程经济效益的目的.该研究可为实际沼气工程运行管理提供数据参考.
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