Toxicity mitigation and solidification of municipal solid waste incinerator fly ash using alkaline activated coal ash

• Published in: Waste management (Elmsford) 2012-08, Vol.32 (8), p.1521-1527
• Main Authors: Ivan Diaz-Loya, E., Allouche, Erez N., Eklund, Sven, Joshi, Anupam R., Kupwade-Patil, Kunal
• Format: Article
• Language: English
• Subjects: AEROSOL WASTES; ALKALINE EARTH METALS; Applied sciences; ARSENIC; ASHES; BARIUM; BUILDING MATERIALS; CARBONACEOUS MATERIALS; CHEMICAL ANALYSIS; CHROMIUM; COAL; Coal ash; Coal Ash - chemistry; Coal Ash - toxicity; COMBUSTION PRODUCTS; COMPRESSION STRENGTH; Compressive Strength; CONCRETES; Construction Materials; CRYSTALLOGRAPHY; DISSOLUTION; Elastic Modulus; ELECTRON MICROSCOPY; ELEMENTS; Encapsulation; ENERGY SOURCES; Exact sciences and technology; FLEXURAL STRENGTH; FLY ASH; FOSSIL FUELS; FUELS; HEAVY METALS; ICP MASS SPECTROSCOPY; Incineration; Incinerator ash; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; Leachability Test; LEACHING; MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; MASS SPECTROSCOPY; MATERIALS; Maximum Allowable Concentration; MECHANICAL PROPERTIES; MERCURY; METALS; MICROSCOPY; Microscopy, Electron, Scanning; NONDESTRUCTIVE ANALYSIS; Other wastes and particular components of wastes; PARTICLE SIZE; Pollution; RESIDUES; SCANNING ELECTRON MICROSCOPY; SELENIUM; SEMIMETALS; SEPARATION PROCESSES; SILVER; SIZE; SOLID WASTES; SPECTROSCOPY; TRANSITION ELEMENTS; Urban and domestic wastes; URBAN AREAS; WASTES; Water Pollution, Chemical - analysis; X-Ray Diffraction; X-RAY EMISSION ANALYSIS; X-RAY FLUORESCENCE ANALYSIS
• ISSN: 0956-053X; 1879-2456
• DOI: 10.1016/j.wasman.2012.03.030

► Incinerator fly ash (IFA) is added to an alkali activated coal fly ash (CFA) matrix. ► Means of stabilizing the incinerator ash for use in construction applications. ► Concrete made from IFA, CFA and IFA-CFA mixes was chemically characterized. ► Environmentally friendly solution to IFA disposal by reducing its toxicity levels. Municipal solid waste (MSW) incineration is a common and effective practice to reduce the volume of solid waste in urban areas. However, the byproduct of this process is a fly ash (IFA), which contains large quantities of toxic contaminants. The purpose of this research study was to analyze the chemical, physical and mechanical behaviors resulting from the gradual introduction of IFA to an alkaline activated coal fly ash (CFA) matrix, as a mean of stabilizing the incinerator ash for use in industrial construction applications, where human exposure potential is limited. IFA and CFA were analyzed via X-ray fluorescence (XRF), X-ray diffraction (XRD) and Inductive coupled plasma (ICP) to obtain a full chemical analysis of the samples, its crystallographic characteristics and a detailed count of the eight heavy metals contemplated in US Title 40 of the Code of Federal Regulations (40 CFR). The particle size distribution of IFA and CFA was also recorded. EPA’s Toxicity Characteristic Leaching Procedure (TCLP) was followed to monitor the leachability of the contaminants before and after the activation. Also images obtained via Scanning Electron Microscopy (SEM), before and after the activation, are presented. Concrete made from IFA, CFA and IFA-CFA mixes was subjected to a full mechanical characterization; tests include compressive strength, flexural strength, elastic modulus, Poisson’s ratio and setting time. The leachable heavy metal contents (except for Se) were below the maximum allowable limits and in many cases even below the reporting limit. The leachable Chromium was reduced from 0.153 down to 0.0045mg/L, Arsenic from 0.256 down to 0.132mg/L, Selenium from 1.05 down to 0.29mg/L, Silver from 0.011 down to .001mg/L, Barium from 2.06 down to 0.314mg/L and Mercury from 0.007 down to 0.001mg/L. Although the leachable Cd exhibited an increase from 0.49 up to 0.805mg/L and Pd from 0.002 up to 0.029mg/L, these were well below the maximum limits of 1.00 and 5.00mg/L, respectively.