EXPERIMENTAL INVESTIGATION ON CONSOLIDATION PROPERTIES OF FIBER REINFORCED MUNICIPAL SLUDGE

A large amount of sludge is often produced in the environment regulation and dredging process of urban river. It has important significance for improving the urban ecological environment and economic sustainable development to safely and efficiently dispose this kind of municipal sludge. Municipal sludge usually has high moisture content, void ratio and compressibility. More importantly, it has a very high fraction of organic and fine particles. It is therefore hard to reduce the total volume through mechanical dehydration. For this reason, accelerating the mechanical dehydration rate and improving the consolidation properties are the top priority during disposing and utilizing the sludge, which is also one of the most significant issues in this subject. In this investigation, the method of discrete short fiber reinforcement technique is proposed and applied to deal with municipal sludge. In order to study the effect of fiber reinforcement on sludge consolidation properties, a series of oedometer tests are conducted on sludge with different fiber contents(0, 0.05%, 0.1%, 0.2%, 0.4% and 0.8%).The effect of fiber addition on the coefficient of consolidation and permeability is analyzed. The results show that the deformation and void ratio of sample increase significantly with increasing fiber content while the consolidation time and coefficient of compressibility decrease with increasing fiber content under the same load conditions. When the fiber content is 0.1%, these changes are most significant, which can be considered as the optimal fiber content. In addition, the results prove that the inclusion of fiber can increase the consolidation coefficient and hydraulic conductivity of sludge. The corresponding consolidation efficiency and mechanical properties are also improved.