Evaluating Solidification Characteristics of Textile Dyeing Sludge with Addition of Portland Cement and Attapulgite

Abstract

Cement-based solidification/stabilization (S/S) has been considered as an effective method to deal with hazardous wastes such as textile dyeing sludge. In this study, sludge from textile wastewater treatment plant was solidified by Portland cement and attapulgite at different mass ratios (sludge 0.1~0.8, cement 0.1~0.8, attapulgite 0.1~0.8), and the characteristics of the solidified blocks were evaluated. The maximum unconfined compressive strength (UCS) of 15.8 MPa was obtained at 28 d when the mass ratio of attapulgite, sludge and cement was 0.1:0.1:0.8, while in toxicity characteristic leaching procedure (TCLP) test, relatively low concentrations of COD (100~150mg/L) in the leachate were found when the mass ratio was set to 0.3:0.1:0.6. Results of XRD and SEM/EDS indicated the existence of calcium silicate hydrate (CSH) in the solidified blocks. ANOVA results proved that the quadratic model could be utilized to characterize the relationship between COD of the leachate and the components in the mixture.