Tanapon Phenrat, Taha F. Marhaba, and Manaskorn Rachakornkij

pp. 65 - 75

Abstract

By solidification and stabilization (S/S) with Portland cement and lime, it is possible to reduce arsenic
concentration in leachate of the arsenic-containing sludge from arsenic removal process by coagulation with
ferric chloride. From the initial arsenic concentration in leachate of unsolidified /unstabilized sludge which
was around 20.75 mg/L, the arsenic concentrations in leachate of solidified/stabilized waste were reduced
to 0.3, 0.58, 1.09, and 1.85 mg/L for the waste-to-binder ratios of 0.15, 0.25, 0.5, and 1, respectively, due to
the formation of insoluble calcium-arsenic compounds. To be more cost effective for the future, alternative
uses of these S/S products were also assessed by measurement of compressive strength of the mortar specimens. It was found that the compressive strengths of these matrices were from 28 ksc to 461 ksc. In conclusion, considering compressive strength and leachability of the solidified matrices, some of these solidified/
stabilized products have potential to serve as an interlocking concrete paving block.