Taking wind into account in the design of waste stabilisation ponds

Abstract

Up to now, most investigations on the dependency of the fluid flow patterns and performance of waste stabilisation ponds (WSPs) on wind speed and direction and pond layout have been performed using 2D and 3D CFD steady state isothermal models. 3D non steady state models integrating thermal processes and boundary conditions taking into account the full influence of meteorological factors are likely to provide more realistic predictions of WSP performance. Such modelling was undertaken for 4 pond layouts, 2 without baffles and 2 with baffles. Wind speed and direction were kept constant throughout each simulation while other meteorological forcings were derived from field measurements. Twelve wind directions and 2, 4 and 6 m s(-1) wind speeds were considered for each WSP layout. Simulations allowed verifying that the pond performance is dependent on the wind direction and velocity, that baffles may improve WSP performance and that the addition of well-designed baffles has the advantage of reducing its sensitivity to the wind.

Oxidation pond for municipal wastewater treatment

“…The factors related to bacteria removal include the direction, speed of wind, and the presence of baffles, particularly L-shaped baffles, where winds blowing parallel to the inlet-outlet of the pond produce poorer results as compared to the orthogonal orientation of the pond. Nevertheless, the results may vary with increasing wind speeds (Badrot-Nico et al 2010). Wind coupled with pond geometry can likewise have an impact on treatment performance.…”

Removal improvement of bacteria (Escherichia coli and enterococci) in maturation ponds using baffles

“…Furthermore, they are consistent with studies carried by Pearson et al (1995) on a pilot scale. According to (Badrot-Nico et al 2010) the addition of baffies had a positive impact on the bacterial removal and on the sensitivity to wind direction. Before the introduction of the baffles, the outlet was already reached 1 h 40 after the injection.…”

On the hydrodynamics and treatment efficiency of waste stabilisation ponds: From a literature review to a strategic evaluation framework

“…However, an opposite direction of the wind will entail an 81% increase in the treatment efficiency. When the wind direction is normal to the water flow, the effluent E. coli count was not significantly different from the no-wind situation.Different conclusions were drawn byBadrot-Nico et al (2010) when investigating the effects combination with baffles on the treatment efficiency of WSPs. Instead of the…”