餐厨垃圾湿式厌氧消化最优有机负荷及失稳指标

为探究餐厨垃圾湿式厌氧消化最佳有机负荷及失稳预警指标，在(36±1) ℃单相连续搅拌条件下进行有机负荷(OLR)梯度实验。通过理论及数学分析确定90%含水率餐厨垃圾湿式厌氧消化的最佳OLR和失稳指标。当OLR（以VS计）为2.94 g?(L?d)-1时，挥发性固体去除率、甲烷产率、容积沼气产率分别为78%、0.58 L?g-1VS、2.99 L?(L?d)-1，此时厌氧反应器达到最佳运行状态。一定浓度的游离氨(FAN)会抑制微生物活性，触发挥发性脂肪酸(VFA)的积累，造成容积沼气产率降低，第36天，当OLR增至3.21 g?(L?d)-1时，FAN浓度升至区域峰值207 mg?L-1，但随后骤降35.9%（39 d），分别造成VFA和挥发性脂肪酸浓度与碳酸氢盐碱度的比值(VFA/TA)从第37天的1 897 mg?L-1、0.22升高至第47天的4 755 mg?L-1、0.73，系统进入抑制稳定状态，最终导致容积沼气产率从第47天的2.66 L?(L?d)-1降至第48天的1.88 L?(L?d)-1，系统恶化。协同分析表明，当VFA和VFA/TA分别达到2 500 mg?L-1和0.35并出现持续上升的现象时，能提前7～8 d对90%含水率餐厨垃圾湿式厌氧消化系统的失稳提出预警。

Exploration of optimal organic loading rates and instability indicators in wet anaerobic digestion of kitchen waste

In order to explore the optimal organic loading rates (OLR) and instability warning indicators of anaerobic digestion(AD) of kitchen waste（KW), an OLR gradient experiment of AD of 90% water content KW was carried out under single-phase continuous stirring condition at (36±1) ℃. Through theoretical and mathematical analysis, it'sfound that the anaerobic digester achieved the best operating state,when OLR=2.94 g?(L?d)-1(calculated by VS),the reductionin volatile solid is 78%, the methane production rate is 0.58 L?g-1 VS, and the volume biogas production rate is 2.99 L?(L?d)-1. In essence, in the process of wet anaerobic digestion of KW, a certain concentration of free ammonia nitrogen (FAN) could drastically inhibit methanogenesis, trigger the accumulation of volatile fatty acids (VFA), and result in reduced volume biogas production rate. On day 36, when OLR increased to 3.21 g?(L?d)-1, FAN concentration rised to the extremum 207 mg?L-1, and then plummeted 35.9% on day 39. Subsequently, VFA and the combination indicator volatile fatty acids/total alkalinity (VFA / TA) increased from 1 897 mg?L-1, 0.22 to 4 755 mg?L-1, 0.73, from day 37 to 47, respectively. In the inhibitory state, acid-base neutralization reaction occurred between FAN and VFA, and the co-accumulation of FAN and VFA led to an inhibited steady state, which eventually caused a sharp decrease in volume biogas production rate from 2.66 L?(L?d)-1 to 1.88 L?(L?d)-1 on day 48, the system deterioration. The synergistic analysis manifested that when VFA and VFA/TA accumulated to 2 500 mg?L-1 and 0.35 simultaneously, the early warning of instability of the 90% water content KW wet anaerobic digestion system could be made. Their warning times range from 7 to 8 days, and the warning orders were basically consistent. This study provided technical reference for efficient operation of small and medium sized biogas engineering for wet anaerobic digestion of KW.