Notice of RetractionEffect of Alkaline Fly Ash on Heavy Metal Speciation in Stabilized Sewage Sludge

Abstract

Mixing sewage sludge with coal fly ash could reduce the mobility of heavy metals in stabilized sewage sludge. In order to access the mobility and bioavailability of copper (Cu), zinc (Zn) and nickel (Ni) in stabilized sewage sludge, five-step sequential extraction method was performed according to the modified Tsessier method. The results showed that application of coal fly ash to sewage sludge increased the percentage of exchangeable Cu and Zn, but decreased the residual phases of Cu and Zn, indicating that mixed sewage sludge with coal fly ash may increase the mobility of Cu and Zn. However, compared with Cu and Zn, the effect of coal fly ash on the mobility of Ni in stabilized sewage sludge was inapparent. Moreover, the residual Ni accounted for 44.6 % to 56.3% of the total Ni in stabilized sewage sludge, indicating that land application of stabilized sewage sludge has the low Ni risk.