03846cas|a2200409 i 4500 20260817172545.0 230399s1994 th uzm rtt 00| a1eng d .b10136113 AIT Thesis no. EV-94-01 Ali, Syed Murtuza Chemical and biological heavy metal dissolution process of sewage sludge Bangkok : Asian Institute of Technology, 1994 64 leaves Thesis ; no. EV-94-01 A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Environment, Resources & Development Thesis (M.Eng.) - Asian Institute of Technology, 1994 Sequential extraction was performed to find out exchangeable, adsorbed, organic, carbonate and residual forms of the metals in the sludge under consideration. Each metal showed binding characteristics of its own. Zn had distinct affinity to the organic ligands present in the sludge, whereas for Cd, Cr, Cu and Ni, dominant form was residual. Pb and Mn were associated mainly with the organic and carbonate forms. Chemical leaching experiments were carried out for five days by varying the pH to 1.5, 2.5 and 3.5. Chemical leaching of different forms were also dependent on metal characteristics. In general; metals in adsorbed, organic and carbonate forms were solubilized more easily than that of residual form. Exchangeable form increased to a considerable extent after leaching. Different forms of metals remained after leaching for the specified period of time was found out and compared to investigate the chemical leaching process. Formation of stable complexes with humic substances, mineral constituents and buffer action due to release of ligands by H+ from metal-ligand complexes were considered responsible for the remaining of different metal forms even after leaching for 5 days at a very low pH 1.5. Solubilization rate of different heavy metals by the bacterium Thiobacillus ferrooxidans was found very fast compared to chemical leaching at the same pH. Other than sulfides; metals in adsorbed, organic and carbonate forms also were found solubilized due to bacterial activity. This solubilization however, was considered either the result of production of excess H2S04 during bacterial leaching process or due to dissociation of metal-ligand complex by bacteria. Metals in residual form, which was mainly sulfides were not leached completely by bacteria which indicated the presence of very stable metal-mineral complex in this form. Sewage Purification Heavy metals removal Umita, Teruyuki, Chairperson Reutergardh, Lars, Examination Committee Stoll, Uwe, Examination Committee Swedish International Development Authority (SIDA), Government of Sweden., Scholarship Donor Asian Institute of Technology. Thesis ; no. EV-94-01 Full-Text http://203.159.5.9/ait-thesis/detail.php?q=B15600 .b10136113 mnait x 240411 2 951012 m a x 0 mnait mnait mnarc 20 40 Barcode : 30050003047544 CREATED : 1994-05-16 RECORD # : i10154838 LPATRON : 0 LCHKIN : - # RENEWALS : 0 # OVERDUE : 0 IUSE3 : 0 TOT CHKOUT : 0 TOT RENEW : 0 Barcode : 30050003047551 CREATED : 1992-12-17 RECORD # : i1015484x LPATRON : 1011379 LCHKIN : 2001-12-19 # RENEWALS : 0 # OVERDUE : 0 IUSE3 : 0 TOT CHKOUT : 14 TOT RENEW : 9 Barcode : 30050160055595 CREATED : 2016-11-05 RECORD # : i12975291 LPATRON : 0 LCHKIN : - # RENEWALS : 0 # OVERDUE : 0 IUSE3 : 0 TOT CHKOUT : 0 TOT RENEW : 0 16537 16537 0 0 0 0 MAIN MAIN mnait 2026-08-17 0 AIT Thesis no. EV-94-01 30050003047544 2026-08-17 17:25:45 1 2026-08-17 20 0 0 0 0 MAIN MAIN mnait 2026-08-17 0 AIT Thesis no. EV-94-01 30050003047551 2026-08-17 17:25:45 2 2026-08-17 20 0 0 0 0 MAIN MAIN mnarc 2026-08-17 0 AIT Thesis no. EV-94-01 30050160055595 2026-08-17 17:25:45 2026-08-17 40