黏土与粉煤灰吸附农村生活垃圾渗滤液的效能及机理

Research on adsorption efficiency and mechanism of clay and coal fly ash for rural domestic waste leachate

分别以黏土和粉煤灰作为吸附剂,研究单一材料下吸附时间、吸附剂投加量和渗滤液初始pH对农村生活垃圾渗滤液吸附效能的影响及吸附机理。综合考虑去除效果、运行成本及可操作性,选择吸附时间为180min、吸附剂投加量为50gL、渗滤液初始pH为自然值(7.5~8.0)作为实际运行工况。结果表明:黏土对农村生活垃圾渗滤液中化学需氧量(CODCr)、氨氮(NH3-N)、总氮(TN)、总磷(TP)的去除率分别为25.58%、14.87%、41.63%和62.25%,粉煤灰为33.01%、18.18%、22.07%和60.46%;黏土对重金属Cr、As、Cd、Ni和Pb的去除率分别为13.04%、43.34%、60.24%、47.52%和61.77%,粉煤灰为10.53%、31.52%、84.30%、65.73%和68.65%。黏土和粉煤灰对渗滤液中污染物的等温吸附较符合Freundlich模型,化学吸附在多种吸附作用中占主导作用。

The effects of contact time,adsorbent dosage and initial pH on adsorption efficiency and its adsorption mechanism of clay and coal fly ash were investigated in batch experiments.Considering the removal effect,operation cost and maneuverability,the contact time of 180 min,adsorbent dosage of 50 g L,initial leachate pH of natural value(7.5-8.0)were chosen as the actual operation condition.The results showed that under this condition,the removal rates of clay and coal fly ash for normal pollutants of rural domestic waste leachate(COD Cr,NH 3-N,TN,TP)were 25.58%and 33.01%,14.87%and 18.18%,41.63%and 22.07%,62.25%and 60.46%,respectively.The removal rates of clay and coal fly ash for heavy metals(Cr,As,Cd,Ni,Pb)were 13.04%and 10.53%,43.34%and 31.52%,60.24%and 84.30%,47.52%and 65.73%,61.77%and 68.65%,respectively.The isothermal dates of clay and coal fly ash for various pollutants in landfill leachate could be well described by the Freundlich adsorption model,and the chemisorption was the dominant mechanism.