Study on Solidification of Chromium-Containing Sludge With Alkali Slag Combined With Attapulgite

Abstract

In order to solve the harm of hazardous waste chromium-containing sludge to humans and the environment, this paper uses attapulgite to strengthen alkali slag to prepare cementitious materials to solidify/stabilize chromium-containing sludge. Single-factor and orthogonal experiments were used to optimize the preparation parameters of alkali slag cementitious materials. The compressive strength, heavy metal leaching toxicity, and microscopic characterization of chromium-containing sludge solidified body were tested to investigate the solidification effect and mechanism of chromium-containing sludge. The results show that: The best content of attapulgite is 4%. The compressive strength of the solidified body decreased with the increase of chromium sludge content, and the leaching concentration of Cr and Cu increased with the rise of chromium-sludge content. The addition of attapulgite enhanced the compressive strength. Compared with the original chromium-containing sludge, the leaching concentration of heavy metals in the solidified body is significantly reduced. The XRD and FTIR analysis showed that the solidified body might solidify/stabilize heavy metals by physical encapsulation of amorphous form and chemical immobilization. This research realizes the use of waste to treat waste and provides the possibility for the application of solidified products in construction.