Fly Ash (FA) is obtained by electrostatic or mechanical precipitation of dust-like particles from the flue gases of furnace fired with coal or lignite at 1100 to 1400°C. About 95-99% of Fly Ash consists of oxides of Si, Al, Fe and Ca, about 0.5 to 3.5% consists of Na, P, K and S and the remainder is composed of trace elements. PFA has also been used as an adsorbing material when applied in treatment effluents. The use of Fly Ash as a chemical conditioner has previously been investigated with results indicating that Fly Ash does facilitate the filtering process since it decreases both specific resistance and capillary suction time. Therefore, the aim of this paper was to assess the potential of PFA as an ameliorant for soil artificially spiked with various Lead compounds (PbSO₄, PbCO₃, PbNO₃ and PbS). Additions of quicklime and Fly Ash to the contaminated soils effectively reduced heavy metal leachability well below the regulatory limits for hazardous wastes. The results showed the effect of PFA on leaching of lead was significant for all the samples. A high interaction value depicting sampling effect over the use of the PFA as an ameliorant was observed. The order of the difference between samples treated with PFA and without PFA was PbNO₃ > PbSO₄ > PbCO₃ > PbS (17 mg L^-1) when compared to that of the control. The results also demonstrated that, effect of filtration and PFA as an ameliorant had a significant effect in reducing toxicity. However, it is important to consider the source of PFA, as certain sources could in essence impart certain toxic elements, defeating the primary purpose of amelioration

Efficient treatment strategies to reduce the toxicity of metal contaminated soil using cost effective techniques such as naturally available ameliorants and industrial waste have emerged. Three easily available amendments were determined: Bone meal, red earth/mud and pulverised fly ash (PFA). The application of ameliorants offered a possible alternative in situ remediation of contaminated sites without disruption to the ecosystem profile. In comparison to other ameliorants Red earth/mud was found to be efficient in intercepting lead leaching from soil amended with different lead compounds based on CEC (Cmol/g). This was associated with the heterogeneous adsorbency principle in red mud which is associated with its ability to bind metal ions (M 2+ ) onto one or two types of surface sites at pH< 6.0. However areas that need to be studied and assessed (for public health concerns) critically for wide spread application of all the ameliorants include off-site effects of the ameliorants.