Solidification efficiency and mechanism of conventional curing agents for sewage sludge stabilization and dewatering

One of the challenges faced by sewage sludge treatment and disposal is its higher water content, and how to efficient dewater those hazardous materials properly is welcome in practice. This study stabilized the sewage sludge via the using of conventional curing agents and calcined aluminum salts, and the corresponding dewatering mechanisms and structural changes of the stabilized sludge were further comparable analyzed. Experimental results showed that wollastonite and kaolin exhibit a relative higher dewatering efficiency as compared to other conventional curing agents; however the releasing rate of heavy metals of Cu, Cr, Ni for kaolin solidification and Zn, Pb for wollastonite solidification is higher than the sludge samples solidified by other curing agents. For comparison, the sludge samples solidified by calcined aluminum salts (AS), calcium ash, Mg-based curing agent, tricalcium aluminate (C₃A) show a lower heavy metals leaching potential and unconfined compressive strength. In addition, the economic characteristics and local availability of AS, calcium ash, C₃A and CaO makes it have a broad prospect in extension and application. These findings are of great significance for stabilization and dewatering of sewage sludge.