Leachability of heavy metals from solidified sludge

Abstract

Solidified sludge undergoes progressive depletion of the alkalinity materials under natural weathering condition and releases out of heavy metals. The leaching of heavy metals from solidified sewage sludge was studied by acid neutralization capacity (ANC) test and flow-through leaching test. The results of ANC test showed that heavy metals release at high concentration when the pH of extract lowers than 6. The disintegration of solidified sludge and the transformation of heavy metals are the main reasons for the resolubilisation of contaminants. Flow-through leaching test indicated that leaching of heavy metals from solidified sludge occurs in a slow way. A mathematical model has been developed to predict the stabilization time of heavy metals in solidified sludge. The research results showed that decreasing hydraulic conductivity is more important than cement addition for controlling the release of heavy metals from solidified sludge.sludge, heavy metal, leaching model, stabilization time

Review of Chromium Residue and Chromium-containing Waste Water Treatment

“…50678075) funded by the national natural science foundation of China (NSFC), was completed in January 2007-December 2009. Prof. Zhang's existing research results show that compaction sludge with low permeability can intercept metal pollutants transfer by reducing the seepage flow [28]; and that sludge can fix the metal ion without the exogenous nutrients by the microbial anaerobic breath [29,30]; and that sludge is a promising reaction barrier material [31][32][33]; and that in the aspect of heavy metals environmental risk, sludge barrier is feasible [34]. From those research work, the basic scientific principles of "Reducing barriers" is confirmed.…”