Solidification/stabilization of fly ash from city refuse incinerator facility and heavy metal sludge with cement additives

TLDR: The results show that the solidified matrix containing 40% fly ash and 60% cement with heavy metal sludge was the formulation that has the highest fly ash content with a satisfactory strength and was able to immobilize the heavy metals both found in theFly ash and sludge based on the toxicity characteristic leaching procedure (TCLP) test.

Abstract: Solidification and stabilization are well-known technologies used for treating hazardous waste These technologies that use cementitious binder have been applied for decades as a final treatment procedure prior to the hazardous waste disposal In the present work, hazardous waste like fly ash containing high concentrations of heavy metals such Zn (471556 mg/kg), Pb (130056 mg/kg), and Cu (53472 mg/kg) and amounts of Ag, Cd, Co, Cr, Mn, and Ni was sampled from a city refuse incinerator facility This fly ash was utilized in the solidification/stabilization of heavy metal sludge since fly ash has cement-like characteristics Cement additives such as sodium sulfate, sodium carbonate, and ethylenediaminetetraacetic acid (EDTA) was incorporated to the solidified matrix in order to determine its effect on the solidification/stabilization performance The solidified matrix was cured for 7, 14, 21, and 28 days prior for its physical and chemical characterizations The results show that the solidified matrix containing 40% fly ash and 60% cement with heavy metal sludge was the formulation that has the highest fly ash content with a satisfactory strength The solidified matrix was also able to immobilize the heavy metals both found in the fly ash and sludge based on the toxicity characteristic leaching procedure (TCLP) test It also shows that the incorporation of sodium carbonate into the solidified matrix not only further improved the compressive strength from 036 MPa (without Na2CO3) to 054 MPa (with Na2CO3) but also increased its leaching resistance