Stabilization ponds are an economical and efficient method of waste
water treatment in small communities. This form of wastewater treatment
relies upon the natural ability of a body of water to achieve
self-purification. Self-purification means reduction of fecal coliform bacteria,
biochemical oxygen demand, and organic content, and returning the dissolved
oxygen level to desirable levels. Overall efficiency of waste stabilization
ponds is a function of many interacting processes. To gain a better
understanding of the important factors and for insight into methods of
stabilization pond management, a study of the physical, chemical and
biological processes has been initiated. In an earlier report (Luck and
Stefan, 1990) field observations on water temperature and dissolved oxygen
stratification in the Harris, Minnesota, wastewater stabilization ponds were
reported. The alternating mixing and restratification of these ponds over
periods of hours or days were documented. These physical processes which
are in response to time-variable weather underlie the water chemistry and
The ultimate goal of the study is to develop a water quality model for
wastewater stabilization ponds, in order to predict the effluent water quality
at the time of release. As a first step a water temperature model, including
stratification is developed herein. This report describes that model and its
ability to predict observed temperature distributions and stratification periods
in the ponds. Intermittent stratification, sometimes lasting several days, has
a strong effect on sediment/water interaction and vertical transport of
dissolved oxygen, nutrients and phytoplankton in the pond. It is therefore
considered necessary to first develop a model to simulate stratification and
mixing as a basis for a dynamic water quality model.
Gu, Ruochaun; Stefan, Heinz G..
Numerical Simulation of Stratification Dynamics and Mixing in Wastewater Stabilization Ponds.
St. Anthony Falls Hydraulic Laboratory.
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