Factors affecting the leaching of heavy metals (Ni+2, Pb+2, Cr+3) contained in sludge waste stabilization/solidification by hydraulic benders, Part I: water/cement and waste/cement ratio in S/S mortars

The aim of the present paper is to investigate the effect of the water/cement ratio (w/c) (0.4 and 0.6) and the amount of hazardous waste (W/c) (10, 20, 25, 30, and 45%) incorporated on the leaching of heavy metals from a cementitious solidified materials. Mechanical strength of the S/S materials was evaluated at 28 days of cure. Specimens that have shown a good mechanical strength for the two water/cement ratios were used to make this study succeed. XRD analysis has shown the presence of heavy metals within the structure of S/S materials which explains immobilization of heavy metals contained in the waste by the S/S process. Amount of heavy metals released to the environment was evaluated by several leaching tests, namely, TCLP (toxicity characteristic leaching procedure), pore water (PW) and maximum mobile fraction (MMF), and monolithic leaching test (MLT). Monolithic specimens were evaluated under dynamic leaching conditions for 64 days with periodic leachant renewal on two aggressive media, sulfatic attack and in demineralized water. (c) 2016 American Institute of Chemical Engineers Environ Prog, 36: 93-103, 2017