pH对厨余废物两相厌氧消化中水解和酸化过程的影响

通过间歇实验探讨了pH对厨余废物两相厌氧消化中水解和产酸过程的影响,详细考查了厨余废物在4个pH(pH =5 ,7,9,11)条件下的水解率、挥发酸(VFA)产量和速率、有机酸的组分和水解酸化产物的分配.实验结果表明,控制pH为7时,厨余废物具有更高的水解和酸化率,以水解酸化液体中TOC、COD与固液混合液中总COD、TOC比值表示的厨余废物水解率在实验第9d分别达到86%和82 % ,VFA浓度在实验第4d达到3 6g·L- 1 ,VFA产量是未调节pH时的2倍.在pH为7时,水解酸化产物中乳酸浓度相对较低,VFA中主要以丁酸和乙酸为主,丙酸很少.控制pH为7不但可以提高水解酸化效率,而且为后续产甲烷过程提供了更有利的基质,从而优化了厨余废物处理的两相厌氧消化工艺

The influence of pH on hydrolysis and acidogenesis of kitchen wastes in two-phase anaerobic digestion

Batch experiments were carried out to determine the effect of pHon hydrolysis and acidogenesis of kitchen wastes in the two-phase anaerobic digestion. The solubilization rate and VFA production rate of kitchen wastes with controlled-pH at 5, 7, 9 and 11 were firstly evaluated. The constituents of individual organic acids and the distribution of the feeding COD over the different digestion products at various pHlevels were subsequently investigated. The results showed that higher hydrolysis and acidogenesis rates were obtained, when the pH value was kept at 7. And about 86% of TOC and 82% of COD were solubilized after 9days and the maximum VFA concentration of 36g·L^-1 was achieved on the forth day. When the pH value was kept at 7, lactic acid concentration was relatively low, and acetic and butyric acid were predominant VFA, while propionic acid took a relatively little part. Controlling pHat 7 increased the hydrolysis and acidogenesis rates of kitchen wastes and provided the substrates favorable to the subsequent methanogenesis, resulting in the optimization of the whole two-phase anaerobic digestion.