Physico-chemical characterization of water extracts of different coal fly ashes and fly ash-amended composts

The pH, conductivity and the concentration of 15 selected elements were measured in the water extracts of five coal fly ash samples collected from Savannah River Site (SRS) and one from South Carolina Electric and Gas (SCE & G) power plant. This work was intended to study the differences in the physico-chemical properties of SRS fly ash samples relative to those of a reference sample (SCE & G) and to make fly ash-amended composts for agricultural use. Similar analyses were also performed in water extracts of a commercial organic manure, ‘Gotta Grow’, that was composted with one of the fly ash samples (SRS 484-D) in different proportions. Our results show that fly ash samples used in this study differ considerably in pH, conductivity, and elemental composition and that transition metals appear to bind more tightly on smaller particles than on larger ones. The elementally rich manure, ‘Gotta Grow’, is not suitable to study the effects of fly ash on the elemental release from fly ash-amended composts. Low grade or home-made organic composts are being investigated as possible choice for making ly ash-amended composts.