Several on-site greywater treatment systems are under development including biofiltration, whose efficiency is influenced by the filter media. Therefore, the main objective of this study was to evaluate the influence of the type of filter media and their grain size in the removal of organic and microbial pollutants from greywater. Hence, three types of local filter media of different grain size were used for the pre-treatment of greywater. Their removal potential and clogging time were evaluated and compared. The results indicated that the type of filter media and the grain size have an influence on the elimination of organic and microbial pollution from greywater. Indeed, sand of 1 - 2 mm in size obtained the highest removal efficiencies of organic pollutants (67.35% and 78.04% for COD and BOD5 respectively) and microbial indicators (2.07, 1.77 and 2.27 log. units for E. coli, fecal coliforms and enterococci respective ly). Although media of fine texture enhanced the removal efficiencies, they experienced significant clogging problems. To overcome these limitations while enhancing the removal efficiency, 1) pre-treatment stage with coarse materials followed by a treatment with finer materials or 2) the use of a com bination of fine and coarse materials should be considered.

Biofiltration, Fecal Indicators, Granitic Gravel, Greywater, Lateritic Gravel