Physicochemical properties of stabilized sewage sludge admixtures by modified steel slag

• Main Authors: Zhu Xi, Li Fei, Zhang Jingdong, Wu Shengzhe
• Format: Article
• Language: English
• Published: De Gruyter 2018-06-01
• Series: Open Chemistry
• Subjects: steel slag; sludge; solidification and hydration; leaching toxicity; ettringite/iron ettringite
• Online Access: https://doi.org/10.1515/chem-2018-0059

Cement stabilization is used extensively to solidify sludge. However, previous studies suggest that the organic acids in sludge can restrain the hydration processes of cementitious materials. This study presents a new binder (steel slag based materials) whose effectiveness of stabilization was investigated on sewage sludge. Several series of tests for solidified sludge were conducted including the moisture content, compressive strength, shear force, permeability, and toxicity characteristic leaching (TCLP). The result shows that the stabilization effect of physicochemical properties of stabilized sewage by S1* (content 90% steel slag) were better than that of cement. With 20% S1, the moisture content of the sludge could be reduced to 30% at 20+1°C for 7 days; The compressive strength was 74.5 kappa and the permeability coefficient was 5.03 × 10–5 (cm/s); The TCLP was below the limit value. The hydration products of paste and solidified sludge at 1, 3, 14, 28, and 90 days were analyzed by XRD, SEM, and energy spectroscopy to distinguish ettringite/iron ettringite in S1 solidified sludge. the result shows the Needle-like ettringite of S1 possess high iron content and may be Fe–Aft.