Alexander Szabo and Oscar Engle - Svenskt Vatten

5. Previous studies on WSP systems
5.1 Example of computer simulation of WSP geometry
In a test which was executed at Alexandria University, Egypt by Abbas et al. (2006), different
length/width ratios for a WSP were tested in a computer program in order to determine the
degradation of BOD and the amount of dissolved oxygen. In reality, there are always a lot of
parameters affecting the treatment pond which the engineers cannot control, for example
temperature variations, amount of sunlight and wind speed. In the computer model these
parameters were set to a constant value. The hydraulic model was assumed to be of dispersed
flow characteristics.
The influent waste water had the following characteristics: BOD concentration 300 mg/l, DO
concentration 0.0 mg/l and 150 kg/(ha*day) in surface organic loading rate of BOD. The
retention time was set to 31 days, the inflow was set to 0.18 m 3 /s and the pond depth to 1.5 meter.
The water is assumed to move through the pond as completely mixed (Abbas et al., 2006) (see
chapter 3.2). The simulation was executed for the four different length/width ratios which can be
seen in Figure 5.1 below.
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