污泥、淤泥和黏性土的压缩特性对比试验研究

Comparative Experimental Investigation on Compressive Behavior of Sewage Sludge,Dredged Material and Cohesive Soil

目前脱水污泥的含水率在80%左右,仍不能满足污泥后续填埋、焚烧、堆肥等处置要求,因此了解污泥的固结排水规律对于建立污泥脱水的基本理论、进一步提高脱水效果有重要意义。针对这个问题,对比分析了污泥、淤泥和一般黏性土的压缩特性和压缩系数;并通过离心试验研究污泥固结过程中的水分转化过程,提出污泥的三阶段排水规律猜想。结果表明:污泥的压缩特性有其自身的特殊性,其孔隙比大,压缩性大;且压缩曲线是曲线形式,不同于淤泥和一般黏性土的直线;污泥和淤泥的压缩系数非常大,且随着固结压力的增大压缩系数减小速率也非常大。污泥固结过程中不仅自由水的量发生明显减少,结合水的量也显著减少,其固结不仅存在类似淤泥固结过程中的孔隙排水,同时还存在其他形式的水分排出过程。污泥的固结排水可以分出明显的三个阶段,I阶段主要是孔隙排水阶段,II阶段是细胞水、孔隙水的混合排水阶段,III阶段主要是细胞水排水阶段。

At present,the moisture content of the dewatered sludge is about 80%,but it still can not meet the requirements of landfill,incineration and composting. Therefore,studying the consolidation behavior of sewage sludge is of great significance for establishing the basic theory of sludge dewatering and further improving the dehydration effect. The compressive behavior and compression coefficient of sewage sludge,dredged material and cohesive soil are compared and analyzed. The process of water conversion in sewage sludge consolidation is studied by centrifugal test and the three-stage drainage rule of sewage sludge is put forward. The results show that the compressive behavior of sewage sludge has its own specificity. Its pore ratio is large,the compressibility is large,and the compression curve is in the form of curve,which is different from the straight line of dredged material and cohesive soil. The compressibility of sewage sludge and dredged material is very large and the rate of reduction of the compression coefficient as the consolidation pressure increases is also very large. In the process of sewage sludge consolidation,not only the amount of free water reduced significantly,but also the amount of bound water reduced obviously. The consolidation process is not only in the form of pore drainage,but also in other forms of water discharge. The consolidation and drainage of the sewage sludge can be separated into three stages. Stage I is mainly the pore drainage stage,Stage II is the cell water,pore water mixed drainage stage,Stage III is mainly the cell water drainage stage.