Thesis-1978-Phanapavudhikul.pdf (21.6 MB)
The effect of temperature on activated sludge plant operation
thesis
posted on 2012-12-10, 15:53 authored by Suchint PhanapavudhikulThree laboratory and pilot scale, diffused air activated
sludge units were operated as continuous plug-flow tapered
aeration systems at constant temperatures of 10 C, 20 C and 30 C.
Dissolved oxygen was maintained at about 2 mg/l and the sludge was
recycled at the same rate as the sewage feed rate for all the three
units. Synthetic sewage was fed to each unit at four different
detention periods namely 5, 3, 1.5 and 1 hour in turn including
the return sludge. At each detention period the effect of four
different concentrations of mixed liquor suspended solids of 2,000,
3,000, 4,000 and 5,000 mg/l were investigated. Operational parameters
for each run measured included BOD
5
, COD, mixed liquor suspended
solids, suspended solids, dissolved oxygen, turbidity, pH,
free and saline ammonia, nitrite, nitrate, organic nitrogen, sludge
volume index, sludge production, specific resistance to filtration
of sludge, anionic surface active agent, air flow rates and total
phosphates. In addition microscopic examination of the activated
sludges vas,carried out occasionally.
The results obtained indicated that BOD5 and COD
removal efficiencies, air requirements, nitrification increase
with an increase in temperature from 10 C to 30 C. Nitrogen loss
is caused by aerobic denitr1fication. Complete removal of nitrogen
in sewage is possible by aerobic nitr1fication-denitrif1cation
process in the aeration tank of a single-stage activated sludge
unit at 30 C and at high loading. Specific resistance to filtration
of sludge, sludge production rate and phosphate removal decrease with an increase in temperature from 10 C to 30 C. The sludges·
possess better resistance to bulking at higher temperatures and
at low loadings. The average values of detergent removal efficiencies
are well over 88% for all the three units at 1O C, 20 C and
30 C . Metazoa such as rotifers, earth worms and water mites were
numerous at higher temperatures. There is only a marginal saving
in cost for plant operating in tropical country as compared to
that in developed country in spite of the better plant performance in tropical country.
History
School
- Architecture, Building and Civil Engineering
Publisher
© Suchint PhanaparudhikulPublication date
1978Notes
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.Language
- en