固化污泥压缩特性研究

Compression characteristics of solidified sewage sludge

固化技术是污泥进行填埋处置常用的处理技术之一,固化污泥的压缩参数是进行填埋场库容计算和稳定性评价的重要指标。选用水泥作为固化材料,开展了不同材料添加量和不同养护时间条件下固化污泥的压缩特性研究,并从固化污泥水分形态和转化角度对压缩性变化机理进行了探讨。结果表明,即使水泥添加量达到30%,固化污泥的压缩指数也高达0.71,是一种高压缩性的土。水泥的添加量在10%~20%时,固化污泥压缩指数降低显著,但是超过20%以后,压缩指数变化趋于稳定。其原因主要在于污泥中的水分具有较高的结合势能,过多的水泥并不能获得更多的自由水发生水化反应。固化污泥的压缩指数随着养护时间的增加而降低,当达到14 d时趋于稳定,但60 d以后压缩指数又出现降低趋势,其原因主要是微生物逐步分解污泥结合水中的碳氢化合物,有机质含量下降,导致压缩指数降低。

The solidification technology is a general disposal method for sewage sludge landfills, and the compression parameter is an important factor for volume calculation and stability evaluation of landfills. The sewage sludge is solidified by using cement. The researches on the compression characteristics are carried out under different cement contents and curing period conditions. In addition, the compression mechanism is investigated from the viewpoints of water forms and transform. The results show that if the cement content is 30%, the solidified sludge is highly compressed and its compression index is 0.71. The compression index greatly decreases with the cement content of 10%~20%, and it tends to be stable when the cement content is more than 20%. The reason is that the cement can not get more free water for reaction because the water forms are mainly the bound water in the sewage sludge. With the curing period extended, the compression index decreases and becomes stable after 14 days. But the compression index is declined after 60 days, which is caused by decomposed hydrocarbon and decrease of organic contents by the microorganism action.