含固率和有机负荷对厨余垃圾厌氧消化性能及沼渣特性的影响

为提高厨余垃圾厌氧消化性能和促进沼渣资源化利用，以底物降解效能和产甲烷量最大化为目标，分别考察不同进料总固体（TS）含量（含固率）(12%、15%、18%、25%、28%、33%)和有机负荷〔8.5、10.5、13.5 g/(L·d)，以挥发性固体(VS)计〕条件下厨余垃圾的中温厌氧消化特性，并对最优进料参数下沼渣特性和资源利用潜力进行分析. 结果表明:进料TS含量是影响厨余垃圾厌氧消化效能的重要因素，调节进料TS含量至25%时可获得最大累计产甲烷量(16.81 L)和最高单位容积负荷累计产甲烷量(42.01 L/L)，挥发性固体降解率达72.29%，系统运行稳定. 在进料TS含量为25%的条件下，系统累计产甲烷量随有机负荷的增加呈先升高后降低的趋势，有机负荷为10.5 g/(L·d)时，系统累计产甲烷量和挥发性固体降解率最高，分别为24.04 L和79.64%，未产生酸抑制现象. 厌氧消化过程中产生的副产物沼渣中有机质和总养分含量较高，电导率和重金属含量较低，pH适宜，满足《有机肥料》(NY 525—2021)和《绿化用有机基质》(GB/T 33891—2017)的要求. 研究显示:当进料TS含量为25%、有机负荷为10.5 g/(L·d)时，厌氧消化系统运行效能最优；沼渣营养成分较高、生物毒性较低，具有较大资源化利用潜力，后续经脱水处理并提高腐熟程度后可进行应用. 

Effects of Total Solid Content and Organic Loading Rate on Anaerobic Digestion Performance and Biogas Residue Characteristics of Kitchen Waste

In order to improve the anaerobic digestion performance of kitchen waste and promote the resource utilization of biogas residues, in this study, the effects of different feed total solid (TS) contents and the organic loading rates on mesophilic anaerobic digestion of kitchen waste were investigated to maximize the degradation efficiency of substrates and methane production. The characteristics of biogas residue, which was known as anaerobic digestion byproducts, were systematically analyzed under optimal feed conditions to evaluate its utilization potential as resources. The results showed that the TS content of the feed had a dominant effect on the anaerobic digestion efficiency of kitchen waste. When the TS content was 25%, the maximum cumulative methane production (16.81 L) and the highest cumulative methane production per unit volume loading (42.01 L/L) could be obtained; meanwhile, the degradation rate of volatile solids (VS) could reach up to 72.29% and the system could run stably. The effect of organic loading rate on anaerobic digestion performance was investigated under optimal feed TS content of 25%, and the results showed that the cumulative methane production of the system first increased and then decreased with the increase of organic loading rate. The ideal organic loading rate was 10.5 g/(L·d), the acid inhibition was negligible, and the cumulative methane production and VS degradation rate of the system were the highest, which were 24.04 L and 79.64%, respectively. The biogas residue produced by anaerobic digestion contained high organic matter and total nutrient content with low electrical conductivity, low heavy metal content, and moderate pH range. These characteristics of the biogas residue could meet the requirements of Organic Fertilizers (NY 525-2021) and Organic Substrates for Greening (GB/T 33891-2017). Overall, the optimal feed conditions were 25% TS content and 10.5 g/(L·d) organic loading rate, under which the efficiency of the anaerobic digestion system was the highest; the biogas residue had high nutritional contents with low biological toxicity, which shows a great potential to be utilized as ‘organic fertilizers’ after dehydration and decomposition treatment.