The bioavailability of sludge-borne heavy metals as influenced by acidity and salinity gradients | |
| Author | Torotoro, Josephine L. |
| Call Number | AIT Thesis no. EV-98-13 |
| Subject(s) | Sewage sludge Bioavailability Heavy metals |
| Note | A thesis submitted in pa11ial fulfillment of the requirements for the degree of Master of Engineering, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Abstract | The use of sewage sludge as soil amendment has raised concerns regarding the toxic accumulation of its heavy metals component in the environment. The objective of this study was to evaluate the bioavailability of heavy metals in sewage sludge at six levels of salinity (with EC= 2, 4, 8, 19, 31and42 dS/m) and two levels of acidity (with pH= 5 and 6). The effect of salt and metal on seed germination of some test seeds was also evaluated. The mobility and concentration of heavy metals were evaluated with the use of some extraction techniques such as DTPA and sequential extraction by Forstner and Patchineelam. DTPA (diethylenetriamine pentaacetic acid) was successfully used as a single extractant for characterizing bioavailability of heavy metals in sewage sludge (Minnich et al., 1987). Sequential extraction was used to characterize the heavy metals in the sludge into six operationally defined phases: exchangeable, carbonate, easily reducible, moderately reducible, organic and residual. The mobility and bioavailabilty of the heavy metals are related to their solubility and geochemical forms. The sum of metals in exchangeable and carbonate fractions of the sequential extraction scheme was assumed to be the potential plant available form (Xian, 1989) and this was compared with the values resulting from extractions in the presence of DTP A. Significant correlations of bioavailable metals resulting from DTPA and sequential extraction were obtained. |
| Year | 1998 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Energy and Climate Change (Former title: Department of Energy, Environment, and Climate Change (DEECC)) |
| Academic Program/FoS | Environmental Engineering and Management (EV) |
| Chairperson(s) | Preeda Parkpian ;Eckhardt, Ing. Heinz |
| Examination Committee(s) | Apisit Eiumnoh |
| Scholarship Donor(s) | Spanish Government |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 1998 |