Leaching Characteristics of Fly Ash Generated From Suratgarh Thermal Power Plant

Abstract

This paper presents the results of short-term leach tests conducted on slightly alkaline fly ash collected from Suratgarh Super Thermal Power Plant (SSTPP), Sri Ganganagar, Rajasthan, India. ASTM D3987-85 (ASTM) and toxicity characteristic leaching procedure (TCLP) test methods were applied on fresh fly ash (FA-1) and weathered fly ash (FA-2), to understand the leaching characteristics of the elements Cu, Zn, Mn, Fe, Ba, Ca, Co, Cr, Ni, Si, Pb, Sr, Cd, Al, Mg, V, Ti, and As inherent in the SSTPP fly ash. Morphological, quantitative and qualitative elemental as well as mineralogical analyses of fly ash samples were done using XRD, FEG-SEM and ICP-AES techniques. The results showed that both the fly ashes comprise mainly of Bavenite, Silicon Oxide Quartz and Berlinite minerals. The concentration of V (in both FA-1 and FA-2) and Cr (only in FA-1) exceeded the acceptable limit prescribed by New-Zealand waste acceptance criteria for class-A landfill. The TCLP test rendered more mobility to almost all the elements. The concentrations of As (in FA-1), Fe, Cr (not in ASTM FA-2), Mn, Pd and Se (not in ASTM FA-2) in the leachates exceeded the WHO drinking water standards for both TCLP and ASTM tests whereas Ni and Ba surpassed only in TCLP test. The high elemental concentrations of various elements in the leachates thereby suggest a fair amount of pollution potential of SSTPP fly ash.