Characteristic improvement of metal‐contaminated sludge using mineralization technology

Abstract

This study focuses on improving crystalline characteristics of metal-contaminated sludge. The mineralization behavior of Cu/Al or Cu/Fe coexisting in solution is surveyed, and the characteristics of residue and suspension settling are discussed in the context of water content of residue and settling/specific filtration resistance of suspensions. Experimental data show that the hydrate of Cu 4 SO 4 (OH) 6 forms during mineralization of copper sulfate solution when hydroxide ion concentration, reaction time, and temperature are not controlled appropriately. Mineral characteristics of the residue are usually poor when the Cu 4 SO 4 (OH) 6 forms in Cu/Al or Cu/Fe solution. However, Cu 4 SO 4 (OH) 6 can be further transformed into CuO with wet oxidation or ferrite method, respectively (i.e., mineralization treatment). Water reduction of the residue is from 96.8% to 72.8% in the Cu/Al case or 95.6% to 66.6% in the Cu/Fe case, and the mineralized residue volume is only 1/10 of the hydrate sediment. This is particularly beneficial for sludge disposal.

Biosolids and Sludge Management

“…However, copper results were inconclusive. Hu et al (2009) conducted research on the use of mineralization as an innovative method to treat metalcontaminated sludge. By improving the crystalline characteristics of the sludge containing metals through the wet oxidation (ferrite method) of Cu 4 SO 4 (OH) 6 to CuO the percent solids of the sludge were significantly increased and resulted in a residue volume 1/10 of the hydrate sediment.…”