| Author | Bui Cach Tuyen |
| Call Number | AIT Diss. no. EV-92-2 |
| Subject(s) | Sewage--Purification--Heavy metals removal
|
| Note | A doctoral dissertation in partial fulfillment of the
requirement for the Degree of Doctor of Technical Science, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Abstract | The ultimate purpose of this study was focussed on the
finding of a technically feasible and economically viable use of
ABC-PBSS process (Airlift Bioreactor Contactor coupled with
Polyurethane Biomass Support System) to remove heavy metals in the
anaerobically digested sludge before final landspreading as
fertilizer and soil conditioner. ABC-PBSS coupled with Thiobacillus
ferrooxidans is a newly designed combination which exploits the
superior performance of the iron bacteria and the advantages of the
ABC and PBSS for heavy metal removal.
The study was conducted following various batch and continous
runs in which several parameters affecting the operation of ABCPBSS were tested: HRT, feed sludge pH, feed sludge concentration,
DO, ORP . ABC itself can remove heavy metals from anaerobically
digested sludge at high starting pH values of feed sludge and short
HRTs: At feed sludge pH=5.5, 5.75 and 6, Zn, Cd, Ni and Mn were
removed greater than 80% at all HRTs . At the same time, Pb and Cr
were removed less than 20% at all HRTs . Optimum copper removal is
at HRT=0.75 d. At HRT=0 . 5 and 0.65 d copper removal drops
considerably. For all heavy metals analysed at four feed sludge
solids concentrations(l.2, 1.8, 2.4 and 3%), the higher the
concentration of feed sludge, the lower the heavy metal removal
percentage.
Regarding the PBSS design, the vertical plug flow model is
proven most appropriate for the unit operation in terms of
sludge movement and sludge handling. There is a relation between
the bacteria adaptation period of the acclimatised sludge with the
effectiveness of inoculum in various batch runs. Within 60 days,
the longer the adaptation period, the more vigorous the bacterial
activities in terms of heavy metal removal. Over 60 days, the
differences in heavy metal removal were recognised negligible.
PBSS can effectively maintain, or somewhat increase, the
identical level of heavy metal removal while increases the
operation volume of the whole process, thus reduces the unit
operation cost. The treatment cost per cubic meter of sludge in
ABC-PBSS system is evaluated to be about half of that of ABC alone. |
| Year | 1992 |
| Type | Dissertation |
| 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 (EV) |
| Chairperson(s) | Tran, F. T. |
| Examination Committee(s) | Visvanathan, C. ;Harada, H. ;Zhuang, Ya-Hui ;Huynh, Ngoc Phien ;Tyagi, R. D.
|
| Scholarship Donor(s) | ADB-Japan.; |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 1992 |