Premium
A Different Approach for Predicting Reaeration Rates in Gravity Sewers and Completely Mixed Tanks
Author(s) -
Lahav Ori,
Binder Assaf,
Friedler Eran
Publication year - 2006
Publication title -
water environment research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.356
H-Index - 73
eISSN - 1554-7531
pISSN - 1061-4303
DOI - 10.2175/106143006x101764
Subject(s) - sanitary sewer , oxygen , mass transfer , mixing (physics) , mass transfer coefficient , chemistry , environmental engineering , volumetric flow rate , environmental science , hydrology (agriculture) , thermodynamics , geotechnical engineering , chromatography , engineering , physics , organic chemistry , quantum mechanics
A new semiempirical approach is presented for predicting air‐to‐water oxygen transfer rates in mixed tanks and gravity sewers, using methods adopted from mixing theory. First, a flocculation unit was used to impart selected mean velocity gradients ( G ) into a completely mixed tank, from which oxygen was first removed, and dissolved oxygen concentrations were measured with time. Regression analysis was used to fit the rate of oxygen transfer equation against G . The reaeration rate in completely mixed reactors was found to be proportional to G 2 ( R 2 = 0.987). Subsequently, G was linked to headloss in sewers, and the equation was calibrated using a slope‐adjustable, 27‐m‐long, gravity‐flow, experimental sewer (internal diameter, D = 0.16 m). Here, the reaeration rate was proportional to G 1 ( R 2 = 0.981). The equation was compared with existing oxygen transfer models and validated against experimental data from the literature, to which the overall mass transfer coefficient for oxygen, K L a , derived by the new approach, conformed well.