Stabilization/Solidification of Hazardous Wastes Using Fly Ash

Abstract

A simple and inexpensive method of stabilization/solidification (S/S) of hazardous wastes using C-grade fly ash as the only binding agent is presented. The process involves mixing the waste and fly ash and compacting the mixture for less than 3 s at 1.4–6.9 MPa to form a monolith. Toxicity characteristic leaching procedure (TCLP) results for a simulated mixed waste showed that the chromium concentration in the leachate is well below current Environmental Protection Agency (EPA) limits. For this particular waste, TCLP results were not significantly affected by the ratio of waste:fly ash in the block due to the limited range of waste concentration that can be processed. Furthermore, it is shown that the optimum operating conditions are at a waste pH of 9.2 and an applied pressure of 4.65 MPa.