温度波动对城市有机生活垃圾高温厌氧消化工艺影响

模拟由于加热失败导致温度从55℃突降到20℃(室温左右),且在20℃时持续时间分别为1h、5h、12h和24h,对高温厌氧消化处理城市有机生活垃圾工艺的影响进行了实验研究.温度突降以及恢复所需时间均在2h以内.正常状态下有机负荷为8.0g·(L·d)^-1,停留时间为15d.结果表明,温度突降后,产气量几乎降为0,总挥发性脂肪酸(VFA)和乙酸、丙酸含量快速积累,pH值也随之下降.但系统较高的缓冲能力使得pH值在正常范围内波动,并不影响反应器的运行.随着持续时间的延长,产甲烷菌等微生物的衰减上升,导致其产甲烷恢复时间延长.高温条件下温度波动不但影响产甲烷过程而且影响水解和发酵过程.但整个反应在温度突降后可以恢复,说明厌氧高温微生物对温度变化具有较好的恢复能力.

Effect of Temperature Fluctuation on Performance of Thermophilic Anaerobic Digestion for Treating Organic Fractions of Municipal Solid Waste

The laboratory-scale daily fed experiment study was carried out to assess the effect of temperature fluctuation on performance of the thermophilic reactors for organic fraction of municipal solid waste (OFMSW). The temperature of the reactor was lowered from 55 degrees C to 20 degrees C in case of heating failure and the duration in the low temperature were 1, 5, 12 and 24h respectively. The time of downward and upward temperature were within 2h. The organic loading rate was 8.0 g (L x d)(-1) in the steady-state and retention time was 15 d. The results show that the biogas production almost stop and total VFA, VFA such as acetate and propionate are rapidly accumulated when the temperature fluctuated, accompanied by the fall in pH. But the pH values would be in the normal range for the high buffering capacity in the digesters. The delay time of methane production restored was 3, 11, 56 and 72h respectively. It showed the longer the duration in low temperature, the more the decay of methanogenic archaea. Temperature fall not only affected the methanogensis but also the hydrolysis and acidification. Thermophilic microorganisms appeared to be highly resilient during temperature fluctuated process.