Heavy metal extraction from PCB wastewater treatment sludge by sulfuric acid

• Published in: Journal of hazardous materials Vol. 177; no. 1; pp. 881 - 886
• Main Authors: Kuan, Yu-Chung, Lee, I-Hsien, Chern, Jia-Ming
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 15.05.2010; Elsevier
• Subjects: Applied sciences; Cations; Chemical engineering; Electronics; Exact sciences and technology; Extraction; General purification processes; Heavy metal; Industrial Waste - prevention & control; Metals, Heavy - isolation & purification; Other industrial wastes. Sewage sludge; Pollution; Reactors; Sewage - chemistry; Sludge; Sulfuric acid; Sulfuric Acids - chemistry; Waste Management - methods; Wastes; Wastewaters; Water Pollutants, Chemical - isolation & purification; Water treatment and pollution; Extraction; Sludge; Heavy metal; Sulfuric acid; Metal ion; Polychlorobiphenyls; Sewage sludge; Waste water; Pollution; Batchwise; Solid waste; Manufacturing; Waste water purification; Mathematical model; Reactor
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2009.12.115

Heavy metals contaminated wastewater sludge is classified as hazardous solid waste and needs to be properly treated to prevent releasing heavy metals to the environment. In this study, the wastewater treatment sludge from a printed circuit board manufacturing plant was treated in a batch reactor by sulfuric acid to remove the contained heavy metals. The effects of sulfuric acid concentration and solid to liquid ratio on the heavy metal removal efficiencies were investigated. The experimental results showed that the total and individual heavy metal removal efficiencies increased with increasing sulfuric acid concentration, but decreased with increasing solid to liquid ratio. A mathematical model was developed to predict the residual sludge weights at varying sulfuric concentrations and solid to liquid ratios. The trivalent heavy metal ions, iron and chromium were more difficult to be removed than the divalent ions, copper, zinc, nickel, and cadmium. For 5 g/L solid to liquid ratio, more than 99.9% of heavy metals can be removed from the sludge by treating with 0.5 M sulfuric acid in 2 h.