Municipal solid waste incineration (MSWI) fly ash washing pretreatment by biochemical effluent of landfill leachate: a potential substitute for water.

Sulfate-rich biochemical effluent of landfill leachate (BEL) resulting from aged refuse bioreactor was employed to wash municipal solid waste incineration (MSWI) fly ash. The dechlorination ability of BEL was found to be nearly equivalent to redistilled water (RW), and the concentrations of lead (Pb) and zinc (Zn) in the washing solution resulting from the BEL washing process were lower than that of the RW washing process. Fourier transform infrared (FTIR) analysis indicated that the formation of calcium sulfate and hydroxides in fly ash after BEL washing and their entrapping function could significantly inhibit the leaching of Pb and Zn. Besides, toxicity characteristic leaching procedure (TCLP) tests showed that the BEL washing treatment did not increase the risk of heavy metals leaching from fly ash, and the leaching concentrations of Pb, Zn, copper (Cu) and cadmium (Cd) of BEL washed fly ash were lower than that of RW washed fly ash, which suggested BEL washing treatment could slightly immobilize heavy metals in fly ash. For MSWI fly ash dechlorination, our present results indicated that BEL used in this batch experiment could be a potential substitute for water.