Bioleaching of heavy metals from sewage sludge by Acidithiobacillus thiooxidans—a comparative study

• Published in: Journal of soils and sediments 2012-06, Vol.12 (6), p.900-908
• Main Authors: Wen, Ye-Ming, Wang, Qing-Ping, Tang, Caixian, Chen, Zu-Liang
• Format: Article
• Language: English
• Subjects: Acidithiobacillus thiooxidans; Bacteria; Comparative studies; Earth and Environmental Science; Environment; Environmental Physics; Heavy metals; Leaching; Metal concentrations; Nutrient removal; Oxidation-reduction potential; Sec 3 · Remediation and Management of Contaminated or Degraded Lands · Research Article; Sewage sludge; Sewage treatment; Sewage treatment plants; Sludge; Soil Science & Conservation; Soils; Spectral analysis; Sulfur; Wastewater treatment plants; Zinc
• ISSN: 1439-0108; 1614-7480
• DOI: 10.1007/s11368-012-0520-2

Purpose To understand the bioleaching of metals from sludge by Acidithiobacillus thiooxidans , the aims of this study were to evaluate the experimental conditions affecting the efficiency of removal of the metals, including solids concentration, initial pH, sulfur concentration and inoculum level were examined, and following the bioleaching mechanism was proposed. Materials and methods A. thiooxidans were isolated from collected sludge samples containing bacteria from Fuzhou Jingshan sewage treatment plant, and identification of bacteria by sequencing the 16 s rDNA gene sequences. Conditions affecting the bioleaching and application were conducted by batch experiments. The analysis of Cr, Cu, Pb, and Zn was carried out using an atomic absorption spectrophotometer, and the pH and oxidation–reduction potential (ORP) were measured using a pH meter and an ORP meter. Results and discussion The results show that a high metal leaching efficiency was achieved at low solid concentrations due to decreases in buffering capacity. In addition, the best conditions of the bioleaching included 2 % ( w / v ) solid concentration, 5.0 gL −1 sulfur concentration, and 10 % ( v / v ) inoculum concentration, where the removal efficiencies of Cr, Cu, Pb, and Zn in sewage sludge was 43.6 %, 96.2 %, 41.6 %, and 96.5 %, respectively. Conclusions We found that the bioleaching of Zn was governed by direct and indirect mechanisms, while the bioleaching of Cu, Pb, and Cr was mainly dominated by the bioleaching indirect mechanism. After processing with the proposed techniques, the heavy metals in the sewage sludge did meet the requirement of the national standards.