Impacts of Wastewater Irrigation on Soil and Alfalfa Crop: Case Study from Gaza Strip

摘要

This study was conducted between 2008 and 2009 to investigate the impacts of treated wastewater irrigation on soil and alfalfa crop after 7 years of wastewater irrigation. Beit-Lahia Pilot Project (BLPP) was initiated in 2003 where alfalfa crop was irrigated with partially treated wastewater form Beit-Lahia wastewater treatment plant. A control unit irrigated with well water was initiated in parallel for comparison. Soil and alfalfa samples were collected and analyzed for the main physiochemical, fecal coliform (PC), and heavy metals level through the field trial and the applied wastewater quality was also tested. These results were compared with the available data from 2003 to 2007. Results revealed that there is a concern in using treated wastewater under current quality as it negatively impacted the soil physico-chemical properties. Sodium adsorption ratio and electrical conductivity increased significantly by about 160% and 130%, respectively, due to wastewater irrigation (WWI) in both soil layers compared with well water irrigation. WWI caused slight decrease in soil pH in both surface and subsurface soil layers while it increased the soil organic matter content which varied seasonally due to climatic conditions and alfalfa uptake. Slight metal built up was noticed due to wastewater irrigation while metals level remained in the allowable range for soil by the time of this study. Alfalfa metals uptake was within the permissible range. Occasional high FC (900 and 2100 CFU/ml) level was noticed in the applied wastewater did not cause soil biological contamination as the PC level in the soil at BLPP due to wastewater irrigation was almost 260 CFU/g.