Fecal pollution indicators removal by a vertical Multi-Soil-Layering system in domestic wastewater in Morocco

Abstract

The aim of this study is to evaluate the ability of the vertical Multi-Soil-Layering filter (V-MSL) to remove indicators of fecal pollution from domestic wastewater under Moroccan conditions. To do this, a V-MSL filter measuring 20 cm deep, 60 cm wide, 78 cm high was installed near the guardian's house of the Razi’s middle school in Meknes to treat domestic wastewater. Three hydraulic loads (250 L/m2/day, 350 L/m2/day and 500 L/m2/day) were tested. This filter showed an average reduction of (97.5 ± 0.3)%, (97.7 ± 0.4)% and (96.0 ± 0.7)%, for total coliforms, fecal coliforms and fecal streptococci, respectively. The performance of the filter was not affected a lot when changing the hydraulic head from 250 L/m2/day to 500 L/m2/day. The bacterial load concentrations at the filter outlet are slightly higher than the WHO recommended standard (1000 CFU / 100mL) for reuse of wastewater in irrigation. To remedy this situation, we recommend the adoption of the principle of treatment of excreta at the source by the use of dry toilets and the treatment of gray water only by the V-MSL filter.