| Author | Teerawat Luangurai |
| Call Number | AIT Thesis no.EV-90-8 |
| Subject(s) | Sewage--Purification--Activated sludge process
|
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Abstract | This study aimed to investigate the use of sand-drying beds
in dewatering sludges generated from the Bangkhen Water Treatment
Plant of the Metropolitan Waterworks Authority(MWA) ,Thailand. The
combined sludges from the clarifiers and filter backwashing
were collected and transported to the Asian Institute of
Technology (AIT) for analysis and experiments.
The Buchner funnel tests revealed the optimum dosages of
lime, Magnafloc LT26 and ferric chloride to be 16, 0.06 and 8 %
TS, respectively. With these dosages, the above conditioners
yielded the maximum sludge solids of 11.81, 14.81 and 4.31
kg/(m2 .h) respectively, while the ·nonconditioned sludges had the
maximum sludge solids yield of 2.83 kg/(m2 .h).
Rainfalls did not appear to significantly affect the
performance of the sand-drying beds in dewatering the non-conditioned and conditioned sludges. This was due to the rapid
development of cracks in the sludge cakes within one day of
dewatering, where the rai~ water could pass through and became
the filtrate.
The experiments on sand-drying beds suggested that Magnafloc
LT26 was a better conditioner than lime and ferric chloride in
dewatering this sludge on sand-drying beds. The optimum sludge
loading rate for the Magnafloc LT26 conditioned sludge was found
to be 3. 27 kg/ (m2 . d), while for the non-conditioned , lime conditioned and ferric chloride conditioned sludge, the optimum
solid loading rates were 2.73, 2.14 and 2.57 kg/(m2 .d),
respectively.
A comparison between the cost of using sand-drying beds and
sludge lagoons (which are presently employed at the Bangkhen
Water Treatment Plant) for dewatering indicated that it was more
expensive to use sludge lagoons than sand-drying beds. For a
comparison between the cost of non-conditioned and Magnafloc conditioned sludges on sand-drying beds, the Magnafloc LT26-
conditioned sludge required less capital cost but more operation
and maintenance cost than that of the non-conditioned sludge. |
| Year | 1990 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Other Field of Studies (No Department) |
| Academic Program/FoS | Environmental Engineering and Management (EV) |
| Chairperson(s) | Chongrak Polprasert |
| Examination Committee(s) | Vigneswaran, Saravanamuthu ;Kiran Bhattarai
|
| Scholarship Donor(s) | Government of Australia |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 1990 |