采用人工配制渗滤液回灌模拟填埋柱的方法,研究了回灌渗滤液中pH和VFA对填埋层甲烷化的影响.实验结果表明,回灌渗滤液酸性条件(pH=6)下,且回灌渗滤液中存在一定量的VFA时,填埋层仍可迅速甲烷化;并且VFA浓度越低,填埋层甲烷化过程稳定时间越短,回灌渗滤液pH为7时,保证填埋层仍能快速进入甲烷化阶段的最高VFA浓度不应超过4000mg·L^-1(以C计)。研究结果表明,生物反应器填埋初期,以回灌为目标的渗滤液预处理工艺的出水水质要求可适当降低,这既有利于控制渗滤液预处理的成本,也可避免预处理后渗滤液中有机酸浓度过低,导致填埋层可转化为甲烷的有机碳过量流失。
Two variables that appear to be the most critical in controlling refuse methanogenesis are pH and volatile fatty acids (VFA). A lab-scale simulated fresh MSW bioreactor landfill columns, recirculated with simulated leachate, were setup. The pH and VFA concentration of the recirculated leachate were controlled in 6 -7 and 1 000-6000 mg·L^1 , respectively, and the effect of pH and VFA of recirculated leachate on the methanogenesis in the initial stage of bioreactor landfills were studied. The results indicated that when the recirculated leachate was acidified to pH = 6, methane fermentation was created and maintained even the VFA concentration reached above 1000 mg·L^-1 The time for establishing the steady methane fermentation was shortened when VFA concentration decreased. When the pH of the recirculated leachate was 7, the top VFA concentration of the recirculated leachate should be less than 4000 mg·L ^- 1. In the initial stage of the bioreactor landfill, it was unnecessary to thoroughly treat the leachate for recirculation, not only for saving the cost of leachate treatment, but also for conservation of the carbon source for landfill gas generation in the landfill.