Effects on Soil-Plant System in a Treated Wastewater Irrigated Sunflower Cultivation: Soil Chemical Characteristics, Bioaccumulation of Metals in Soil and Plants

Abstract

The use of wastewater in agriculture is a good way for countries where water resources are facing quantity and quality problems. The goal is to study the effect of treated wastewater irrigation on the physico-chemical characteristics and soil geochemistry amended and unamended on one hand, and to follow the bioaccumulation of heavy metals in soils and sunflowers on the other hand. Wastewater and by-products of Sfax wastewater treatment plants and Agareb wastewater treatment plants are widely used for irrigation. The geochemical analysis of these waters shows enrichment in nutrients (nitrogen and phosphorus) and reveals high levels of exchangeable bases. Compost and sewage sludge brought organic matter and nutrients to the substrates, these elements are essential for the growth and the conservation of plant life. Maximum sunflower development was found in the presence of sewage sludge and following irrigation with Agareb treated wastewater (82 cm in length and 479 lg\gMF soluble sugar in plant tissues). The experimental results also show that the addition of sludge, with small quantities of metals from treated wastewater, to the substrate resulted in a decrease of the exchangeable amounts of these metals. This reduction is probably due to their strong immobilization.