| Author | Soydoa Vinitnantharat |
| Call Number | AIT Diss. no.EV-99-7 |
| Subject(s) | Sewage--Purification--Phenol removal
|
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of
Technical Science, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Abstract | Tluee tasks were carried out to study the capability of the BAC process for the
removal of phenol and 2,4-DCP as a sole carbon source. A lignite based GAC 20 x 30 mesh
size was used in this study.
The first task was conducted to identify the comparative roles of the major reactions
to remove phenol and 2,4-DCP in the BAC system. The major reactions considered were
activated carbon adsorption-desorption, biosorption and biodegradation. Freundlich isotherm
analysis was used to compare the performance of each reaction. Removal of phenol by
biodegradation and adsorption predominated over biosorption. Removal of 2,4-DCP by
activated carbon adsorption was much higher than by biodegradation and biosorption. The
adsorption capacity (Kads) of phenol and 2,4-DCP decreased from 25.04 and 43.75 mg/g in
single solute to 18.95 and 22.18 mg/g in bisolute. In the presence of by-product, Kads of
phenol and 2,4-DCP in single solute decreased whereas in bisolute, only Kads of phenol
decreased. In the desorption experiment, a small fraction of sorbed compounds was
reversible particularly, this was conspicuous in the case of 2,4-DCP. Desorption of sorbed
compounds increased in the presence of by-product with which about 90 % of phenol could
desorbed.
As the second task, the treatability of a mixture of phenol and 2,4-DCP in the BACSBR system was investigated and compared with the conventional SBR system.
Experiments were conducted by increasing the influent concentration, varying SRTs,
varying GAC dosages, and changing the operation schedule of the SBR process. The
difference in effluent concentrations between BAC-SBR and SBR was high at short SRTs
and enlarged by increasing influent organic strength. Among different GAC dosages, there
was no obvious change in the specific removal rate but the removal efficiency increased as
the GAC dosage increased. The removal of phenol and COD reached 94%, and it reached
96% for 2,4-DCP in the BAC-SBR with 0.7 g/l GAC and SRT of 3 days. Only 86% for
phenol and 84% for 2,4-DCP as well as COD were removed in the SBR. The removal
efficiency of phenols in the BAC-SBR and SBR systems were improved when the idle time
increased. However, the effluent concentration of phenols from SBR was about two times
higher than that from the BAC-SBR.
As the third task, bioregeneration of GAC loaded with phenol and 2,4-DCP was
investigated in a batch and the BAC-SBR system. Bioregeneration of 1 g/l of GAC showed
that the sequential assimilation of desorbed compounds in the bulk solution could induce the
successive desorption of sorbed compounds from GAC. From SEM observation, the
microorganisms were seen to be mainly colonized on the outer surface of GAC and some of
them were scattered on the inner parts of GAC. The Freundlich adsorption model was
applied to predict the amount of adsorbate remaining after bioregeneration in the batch
experiment and in the BAC-SBR. The Freundlich parameters obtained from the adsorption
isotherm taking into account the by-product effect on the adsorption could predict the
amount of phenols remaining on GAC with high consistency. In the BAC-SBR,
lll bioregeneration increased as SRT increased. During the BAC-SBR operation, GAC could
adsorb phenols in the fill period and bioregeneration started in the react period. Extending
the idle period could enhance the bioregeneration and buffer capacity consequently to
decrease the irreversible adsorption part on the GAC in the BAC-SBR. |
| Year | 1999 |
| 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 and Management (EV) |
| Chairperson(s) | Preeda Parkpian; |
| Examination Committee(s) | Ha, Sung-Ryong ;Ozaki, Hiroaki ;Chongrak Polprasert ;Rakshit, Sudip K. ;Ishibashi, Yoshinobu ;Shin, Hang-Sik; |
| Scholarship Donor(s) | Government of Japan ; |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 1999 |