Type of Document Master's Thesis Author Nair, Arthur William URN etd-121698-120457 Title Investigation of the Effects of Sequential Anaerobic, Anoxic and Aerobic Zones on Dissolved Oxygen Transfer Parameters in a biological Nutrient Removal Pilot Plant Degree Master of Science Department Environmental Engineering Advisory Committee
Advisor Name Title Randall, Clifford W. Committee Chair Little, John C. Committee Member Love, Nancy G. Committee Member Keywords
- biological nutrient removal
- dissolved oxygen transport
Date of Defense 1998-12-01 Availability restricted Abstractii
INVESTIGATION OF THE EFFECTS OF SEQUENTIAL
ANAEROBIC, ANOXIC AND AEROBIC ZONES ON THE
DISSOLVED OXYGEN TRANSFER PARAMETERS IN A
BIOLOGICAL NUTRIENT REMOVAL PILOT PLANT
Arthur William Nair
C. W. Randall, Chairman
Bench and pilot scale determinations of the volumetric oxygen transfer coefficient, KLa,
were performed on an improved A2/O biological nutrient removal (BNR) pilot plant.
Effluent from a full scale primary clarifier, used as pilot plant influent, was found to have
an alpha (ratio of process to clean water KLa) of 0.71 as determined in a 21 liter bench
scale reactor and an alpha of 0.332 as determined in a 0.45 m 3 aeration basin of the 2.4 m 3
pilot plant. Alpha of a 1:1 mixture of primary clarifier effluent with pilot plant return
activated sludge was determined to be 0.94 at bench scale and 0.71 at pilot scale. An
assay of alphas through the initial non aerated treatment zones of the pilot plant using the
bench scale reactor indicated that alphas peaked in the effluent of the first anaerobic zone
(alpha equal to 1.01) and were lower in the second anaerobic zone and first anoxic zone.
An assay of alphas in the three pilot plant series sideline aeration basins indicated that
alpha was maximum in the first aeration basin (alpha equal to 0.905) and were lower in the
second and third aeration basins (0.716 and 0.661 respectively). A consistent increase in
average surface tension was noted from the first to second to third aeration basins,
however the differences were not statistically significant. A comparison of pilot plant
alphas determined in the first aeration basin following anaerobic nominal hydraulic
retention times of 0.0, 0.21, 0.43, and 0.64 hours yielded alpha values of 0.71, 0.94,
0.64, and 0.74 respectively. Like the assay using the bench scale reactor, the alpha values
at pilot scale peaked following treatment in only one anaerobic zone (nominal HRT of
0.21 hours). The study concludes that short exposures in an initial anaerobic reactor as
required for biological phosphorus removal may benefit oxygen transfer efficiency through
increased alphas, however the benefits of long periods of anaerobic reaction time (over 0.43
hours) are uncertain.
Keywords: Volumetric oxygen mass transfer coefficient, KLa, alpha, BNR, anaerobic
Filename Size Approximate Download Time (Hours:Minutes:Seconds)
28.8 Modem 56K Modem ISDN (64 Kb) ISDN (128 Kb) Higher-speed Access NAIRTHESIS.PDF 288.57 Kb 00:01:20 00:00:41 00:00:36 00:00:18 00:00:01indicates that a file or directory is accessible from the Virginia Tech campus network only.
If you have questions or technical problems, please Contact DLA.