Assessment of an Onsite Grey Water Treatment Wetland for Agricultural Irrigation

Grey water reuse in agriculture may significantly reduce the pressure on freshwater resources. However, inappropriate techniques of grey water treatment may result in contamination of plants, soils and water table. In this research, a horizontal sub-surface flow constructed mini-wetland reactor (HSSFCW) was used to treat the bathroom and laundry grey water of an experimental area located in the central west of Tunisia. Physico-chemical and microbial characteristics of raw and treated grey water were evaluated. We aimed to assess the usefulness of the HSSFCW, in treating grey water for agricultural irrigation purposes. The results indicated that the HSSFCW reduced significantly the organic pollution load of grey water. Indeed, the mini-wetland model showed 83% removal of BOD5, 52% COD, 74% TSS and 71% reduction of grey water turbidity. Moreover, the treated grey water had fewer amounts of mineral pollutants such as nitrate, nickel and lead. Microbial analysis also showed a significant decrease in Escherichia coli count after treatment with the HSSFCW. These results suggest that the constructed mini-wetland reactor has a promising potential to treat grey water for reuse in irrigation.