Experimental Study on Water Stability of Leachate Sludge Solidified /Stabilized by Sulfoaluminate Cement Combined with municipal solid waste incineration (MSWI)

Abstract The leachate sludge is a by-product of municipal solid waste (MSW) leachate disposed by biochemical treatment. In this study, the leachate sludge was solidified with sulfoaluminate cement (SAC) blended with a certain amount of municipal solid waste incineration (MSWI) fly ash. The sludge and cement were mixed well according to a certain ratio, placed in a standard curing box for 28 d and then taken out for water immersion test, with the unconfined compressive strength (UCS) and water softening resistance coefficient (Rf) of the sludge-cement solidified body as the evaluation indexes. In order to explore the water stability of sulfoaluminate cement combined with municipal solid waste incineration (MSWI) fly ash solidified stabilized leachate sludge, the test of strength properties of fly ash-sulfoaluminate cement solidified sludge under immersion conditions was carried out. Fly ash showed good effect in improving the water stability of leachate sludge, and the test results showed that: MSWI fly ash is an effective auxiliary curing agent for sulfoaluminate cement curing leachate sludge, but fly ash doping is not the higher the better, under the condition of the same cement doping, each group of curing specimens for the strength enhancement at 28d have an optimal fly ash doping, which are 10% (cement doping ≤ 20%) and 15% (cement dosage >20%). It can be concluded from the water stability experiments that, in the case of less total curing agent dosage, replacing 10% of cement with 10% of fly ash can achieve better curing effect of leachate sludge, while in the case of more curing agent dosage, the curing effect is better when only cement is used as the curing agent.