Solidification/Stabilization of Sludge Waste from Thermal Power Plants Using Portland Cement

Shahid Rajaee Power Plant, located about 100 km west of Tehran, is one of the Iran’s biggest thermal power plants. During the operation of the plant, different kinds of wastes are produced. Dewatered sludge waste from air heater washing wastewater treatment of the plant was subjected to investigation of the cement-based Solidification/Stabilization (S/S) experiments to reduce the mobility of heavy metals. By reviewing the production procedure of this waste, it can be conjectured that this waste probably contains a variable range of heavy metals such as V, Ni, Zn and Cr. In the present study, the S/S method was used to convert this waste into nonhazardous by using both Portland Cement Type I (CEMI) and standard sand (Ottawa Sand) as additive materials. The compressive strength of the samples with different amounts of waste was examined in order to study the changes in the bearing characteristic of the samples, in comparison with the control sample. Microscopic characteristics of both raw and solidified waste samples were observed using a Research Polarize Microscope (RPM). The compressive strength test results reported only about 30% decrease in the results of the samples with waste, comparing to control concrete sample without waste.