SOME NOTES ON HYDRAULICS AND A MATHEMATICAL DESCRIPTION OF SLOW SAND FILTRATION

Reliable mathematical models that can describe the mechanisms in Slow Sand Filters, SSF, represented by different filter parameters are yet absent. The extremely complicated interactions between physical, chemical, biological and hydraulic conditions are shown in a simplified model. An attempt to apply the rapid filtration empirical formulas for SSF is described in detail. The need for further research and empirical surveys is obvious to determine fundamental filter parameters. The negative effect on the head loss caused by hydraulic negative pressure, “vacuum”, is presented.