Development of equations for calculating the head loss in effluent filtration in microirrigation systems using dimensional analysis

Several equations for calculating the head loss in disc, screen and sand filters when using effluents have been developed by means of dimensional analysis. The variables considered in the equations, other than head loss, were filtration level, filtration area, water density and viscosity, mean diameter of the particle size distribution of the effluent, volume and flow rate across the filter and concentration of suspended solids in the effluent. These nine variables were incorporated into six dimensionless groups obtained through Buckingham's method. Experiments to analyse head losses across filters were carried out using five effluents with 115, 130 and 200 mu m disc filters, 98, 115, 130 and 178 mu m screen filters and a sand filter with an effective grain size of 0(.)65 mm. The equations were satisfactorily adjusted with experimental data. However, both effluent and type of filter influenced the adjustments. (c) 2005 Silsoe Research Institute. All rights reserved Published by Elsevier Ltd