Compression characteristics of solidified sewage sludge

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.