改性污泥用作垃圾填埋场日覆盖材料的研究

Test on Daily Cover Material of Landfill Site Based on Modified Sludge from Municipal Sewage Treatment Plant

为了实现污泥的综合利用,提出将其作为垃圾填埋场日覆盖材料的设想,并通过淋雨、剪切等试验测定了污泥本底及经过炉渣或石灰改性后的各项技术指标。结果显示:①不论生污泥还是熟污泥,在未改性之前均不能作为垃圾填埋场的日覆盖材料;②生、熟污泥分别经炉渣、石灰改性后,在较低的混配比例下含水率接近40%、有机质含量<50%;③当生污泥与炉渣/石灰混配后的含水率≤40%,熟污泥与炉渣混配后的含水率≤44%、与石灰混配后的含水率≤48%时,渗透系数≥10-4cm/s;④熟污泥经过炉渣改性后,所产渗滤液的污染物浓度远低于生污泥的;⑤同种污泥分别与炉渣、石灰进行混配改性后,前者所产渗滤液的COD浓度和pH值小于后者,NH3-N含量则大于后者,但各污染指标值(后者的pH除外)均在垃圾填埋场渗滤液的典型水质范围之内;⑥当生、熟污泥与炉渣混配后的含水率为40%时,其抗剪强度相差甚微,均能够达到垃圾填埋场日覆盖材料的要求。

A tentative idea of realize comprehensive utilization of using sludge as daily cover material of landfill site was put forward to sludge. The various technical indexes of sludge background and sludge modified by slag or lime were determined through rainfall, shear and other experiments. The results show that ：① The crude sludge and digested sludge cannot be used as daily cover material of landfill site before modification. ② After crude and digested sludge are modified by slag and lime, the water content is close to 40% and the organic matter is less than 50% under low mixing ratio. ③When the water contents are equal to or less than 40%, 44% and 48% after mixing crude sludge with lime or slag, gested sludge with slag and lime, the penetration coefficients are equal to or greater than 10^-4 cm/s. ④The pollutant concentration in the leachate after mixing digested sludge with slag is less than that after mixing crude sludge with slag. ⑤ When slag and lime are mixed with the same sludge respectively, the COD concentration and pH of the leachate from the former are smaller than those from the latter, while the NH3 - N concentration is greater than that from the latter. However, with exception to pH of the latter, all the pollution indexes are within the quality range of landfill leachate. ⑥ When the water content is 40% after mixing crude or digested sludge with slag, the shear strengths of the two samples are almost identical, meeting the requirement for daily cover material of landfill site.