The Study On The Solidification/Stabilization Of Municipal Solid Waste Incinerator Fly Ash In Cement Mortars

Disposal of municipal solid waste has become a major problem in many countries around the world. With the benefits of substantial weight and volume reduction and potential energy recovery, incineration has become a promising municipal solid waste(MSW) management option. Despite the fact that incineration reduces volume and mass of the wastes by as much as 80%, there are still residues to be properly managed.The municipal solid waste has been recognized as the hazardous waste. The main reasons are that there are large amount of soluble heavy metals, salts and organic contaminative matter in fly ash.This research is aimed at solidification/stabilization of heavy metals in MSEI fly ash. Effective solidification of fly ash is researched by using cement as solidification agents. The fly ash generated from the incineration of waste and collected by the baghouse precipitator is considered hazardous and should be properly treated.In this thesis, the characterization of MSWI fly ash involved chemical and physical analyses, observation under X-ray Diffraction (XRD) analyses, Toxicity Characteristic Leaching Procedure (TCLP) tests. The washing of FA with acid or other reagents are studied, aiming to find a proper leaching agent for the detoxification of FA based on its leaching behaviors of the FA. The results of the tests show that the optimal condition is using NaOAc as the leaching agent with the content of 0.375mol/l, the initial pH of 3, the Liquid and solid ratio of 40 and leaching time of 60min.The thesis explores mechanism of cement solidification, evaluating the leachingtoxicity of condensates, the compressive strengths of mortar specimens, crystal varieties analyzed by X-ray Diffraction (XRD).The further improvement is that the MSWI fly ash pretreated by water is solidified/stabilified in cement mortars. Results show that the performance of fly ash is unproved considerably by removing large amount of sodium salts and Potassium salts etc, utilizing more fly ash to replace cement in mortars without influencing the condensate performance. Economic evaluation finds that the washing fly ash solidified in cement is a effective method with good economic benefits.The .benefits of using MSWI fly ash in cement mortar are twofold; namely, the cost savings stemming from reduction in cement used, and the ecological advantage of ensuring a final destination for the ash.The future trend of the treatment of fly ash is that the cement solidification and Chemical stabilization combined to obtain a good effect.Chi Donghua (Environment Engineering) Supervised by: Liu Zhenhong...