Effect of Initial Moisture Content on Compression and Strength Characteristics of Urban Sewage Sludge

Urban sludge has the characteristics of high water content and high organic matter content, and has a greater impact on the treatment and resource utilization of sludge. In this paper, standard consolidation and unconfined compressive strength tests of sludge with different water contents were carried out to clarify the effect of initial water content on sludge compression and strength characteristics. The results show that: the higher the initial moisture content of the sludge, the greater the compressibility. When the moisture content is lower than the optimal moisture content (45%), the compression index increases significantly with the increase of the moisture content. After the moisture content exceeds the optimal moisture content, the change of compression index tends to be stable. When the water content exceeds 70%, the compression index shows a steep increase trend with the increase of water content. When the water content is lower than or close to the optimal water content, the sludge has a certain structure. When the initial water content is higher than the optimal water content, the structure of the sludge gradually loses. When the initial moisture content is lower than or close to the optimal moisture content, the stress-strain relationship of the sludge is softened. After the optimal moisture content is exceeded, the stress-strain relationship is hardened. This research can provide a certain theoretical basis and technical support for sludge treatment and resource utilization.