Long-term effects of wastewater reuse on hydro physicals characteristics of grassland grown soil in semi-arid Algeria

Abstract

The raw and treated wastewaters are often evacuated downstream of settlements and widely reused in pre-urban agricultural irrigation. Our study highlights the impact of wastewaters on the soil hydro-physical properties as well as biological activity.Our study was conducted in eastern part of Algeria, on long-term (>60 years) wastewater irrigated grassland to determine the biological component and hydrodynamic soil behavior under these practices. Effects of three wastewater types (raw urban, treated and agricultural effluents) on soil were studied and water was characterized both physically and chemically. Assessment of the effects involved soil porosity, soil hydraulic conductivity and earthworms’ abundance.The results revealed that waters contain high concentrations of organics (BOD 5&COD) and suspended solids (SS). Hydro-physical properties and biological activity showed that irrigation with raw urban wastewater enhances soil earthworm density, porosity and higher water transfer via hydraulic conductivity. Biological activity resulted in ideal pore architecture for materials and solutes transfer, induced a variety of micro morphological transformations in relation to the abundance of earthworm communities mostly endogeic and anecic. Keywords: Wastewater reuse, Earthworms, Hydraulic conductivity, Porosity, Grasslands, Semi-arid