Assessment of Pulverised Fly Ash (PFA) as an Ameliorant of Lead Contaminated Soils
Titel:
Assessment of Pulverised Fly Ash (PFA) as an Ameliorant of Lead Contaminated Soils
Auteur:
Edmond Gatima, Mwinyikione Mwinyihija and Ken Killham
Verschenen in:
American journal of environmental sciences
Paginering:
Jaargang 1 (2005) nr. 3 pagina's 230-238
Jaar:
2005
Inhoud:
Fly Ash (FA) is obtained by electrostatic or mechanical precipitation of dust-like particlesfrom the flue gases of furnace fired with coal or lignite at 1100 to 1400°C. About 95-99% of Fly Ashconsists of oxides of Si, Al, Fe and Ca, about 0.5 to 3.5% consists of Na, P, K and S and the remainderis composed of trace elements. PFA has also been used as an adsorbing material when applied intreatment effluents. The use of Fly Ash as a chemical conditioner has previously been investigatedwith results indicating that Fly Ash does facilitate the filtering process since it decreases both specificresistance and capillary suction time. Therefore, the aim of this paper was to assess the potential ofPFA as an ameliorant for soil artificially spiked with various Lead compounds (PbSO4, PbCO3, PbNO3and PbS). Additions of quicklime and Fly Ash to the contaminated soils effectively reduced heavymetal leachability well below the regulatory limits for hazardous wastes. The results showed the effectof PFA on leaching of lead was significant for all the samples. A high interaction value depictingsampling effect over the use of the PFA as an ameliorant was observed. The order of the differencebetween 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 PFAas an ameliorant had a significant effect in reducing toxicity. However, it is important to consider thesource of PFA, as certain sources could in essence impart certain toxic elements, defeating the primarypurpose of amelioration.
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