The properties and potential utilization in agriculture of fly ash from a typical biomass-fired power plant

The rapid expansion of biomass power plants has led to the generation of enormous amounts of ash, which urgently requires appropriate treatment.In this study, the fly ash from a typical actual biomass power plant was sampled and characterized.The major/trace element composition and leaching characteristics of fly ash were analyzed; the environmental risk was assessed by the risk assessment code (RAC), and the fertilizer availability of fly ash was discussed.The results showed that the fly ash was rich in nutrients and accumulation of harmful trace elements, which may be related to the volatility of elements during combustion.Sequential chemical extraction was employed to reveal the chemical speciation of trace elements.Except for residue fraction, Cd, Zn, and Pb in fly ash mainly exist in carbonate fraction, As was found in Fe-Mn oxide fraction, and Cr, Ni, and Cu were mainly in organic matter fraction.The result of RAC demonstrated that Cd in fly ash needs special attention during utilization.The samples have a high leaching amount of K, Na, and Ca but low leaching amounts of Cr, Ni, Cu, Zn, Cd, As, and Pb.This indicates that fly ash can be used as fertilizer.The concentrations of trace elements were far below the upper limit prescribed by the standard, which indicates that the fly ash was suitable for direct use in agriculture and forestry due to the low contents of toxic elements.The results can provide reference for the management and utilization of fly ash from biomass.