Effects of chelant (EDTA) addition on properties of cement-solidified municipal incinerator fly ash

Abstract

A preliminary study was conducted to investigate the effects of EDTA (a chelant) addition on properties of cement-solidified municipal incinerator fly ash (MIFA) due to its increasing use for the removal of metals from soil and wastes. MIFA specimens (designated MIFA-A and MIFA-B, respectively) from two different municipal incineration plants were solidified by a cement-based technique. Properties studied included unconfined compressive strength (UCS) and leaching toxicity by Toxicity Characteristic Leaching Procedure (TCLP). Regardless of an addition of EDTA, experimental results have shown that UCS values of all the solidified MIFA specimens are greater than the R.O.C. EPA regulatory requirement for landfilling (i.e. 10 kg/cm2). The effect of EDTA addition on UCS was found to be trivial. Results of the Analysis of Variance (ANOVA) for UCS values also showed that the amount of EDTA added was not a controlling parameter in this work. It was found that solidification of MIFA by ordinary portland cement (OPC) alone is able to yield solidified monoliths of satisfactory properties. TCLP results of EDTA-added MIFA specimens also showed a limited effect due to EDTA addition. Whether an addition of other chelants would yield a significant effect on properties of solidified MIFA specimens needs further studies.