| Author | Pandey, Janardan Raj |
| Call Number | AIT Diss. no. EV-90-1 |
| Subject(s) | Sewage--Purification--Activated sludge process
|
| Note | A dissertation submitted in partial fulfillment of the
requirements for the degree of Doctor of Engineering, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Abstract | The increasing dependence on biological treatment to treat
toxic and hazardous wastes emphasize the need for continuing
improvement of treatment methods. Phenol is presently the most
widely used model compound for the study of toxic and inhibitory
organics. In this research , aerobic treatment of phenolic
wastewater by immobilized mixed microbial cells is proposed.
Microbial cell immobilization is defined as the physical
confinement or localization of intact cells to a certain defined
region of space with the preservation of some desired catalytic
activities and offers several advantages for the treatment of
wastewater. These include extremely high cell concentrations, the
protection of cells from the effects of inhibitory substrates and
the possibility of continuous operation and higher stability.
Experiments on immobilized mixed microbial eel 1 ( IMMC)
reactors were conducted to investigate their efficiencies on
phenol removal. Four laboratory - scale IMMC reactors each with a
volume of 1 L, were fed with a synthetic phenolic wastewater
under aerobic condition at the phenol loading rates of 1 - 16
g/(L.d) , based on the initial phenol concentration of 250 mg/L.
The IMMC reactors could reach the steady state, based on phenol
removal , in about 10 days and could remove phenol about 90 % when
the phenol loading rates were equal to or below 8 g/ (L.d) . The
IMMC reactors could maintain high biomass in the reactor (about
13000 - 54000 mg VSS/L), and were able to tolerate organic and
hydraulic shock loadings under the experimental conditions
employed in this study.
(iii)
Data from the laboratory - scale experiments indicate that
at the low phenol loading rates of about 4 g/(L.d), the
contribution from the biofilms adsorbed on the outer surface of
the carrier for phenol treatment was significant and could be
higher than that of the immobilized cells. However, at the phenol
loading rates higher than 4 g/ (L.d), the beneficial effects of
the immobilized cells on phenol removal could be distinctly
observed.
Th e food to microorganisms (F/M) ratios for the IMMC
reactors at the phenol loading rates of 1- 8 g/(L .d ) were 0 . 08 -
0 . 15 mg phenol/(mg VSS.d) in which the observed growth yield for
substrate was found to be in the range of 0.26 - 0.31 mg VSS/mg
COD. These rather low values of growth yield was probably due to
the single step conversion of phenol directly into low energy by products such as C02 a nd H20.
A mathematical mode l was proposed to predict the effluent
substrate concentrations in the IMMC reactor . The substrate
utilization rates due to immobilized microorganisms in the
carrier and due to the suspended microorganisms in the reactor
were also predicted from the mod el. It was found that the
contribution from the suspended growth microorganisms for the
phenol removal in IMMC reactor was negligible when compared to
with those from the immobilized microorganisms in the carrier. |
| Year | 1990 |
| Type | Dissertation |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Other Field of Studies (No Department) |
| Academic Program/FoS | Environmental Engineering (EV) |
| Chairperson(s) | Chongrak Polprasert
|
| Examination Committee(s) | Vigneswaran, Saravanamuthu ;Yamamoto, Kazuo ;Suphat Vongvisessomjai ;Yang, P. Y.
|
| Scholarship Donor(s) | Government of Japan |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 1990 |