WASTEWATER REUSE FOR IRRIGATION ON THE DESERT SANDY SOIL OF EGYPT: LONG-TERM EFFECT

In Egypt, the reuse of sewage water on the sandy soil of El-Gabal El-Asfar Farm took place since 1923. The present work discusses the physical and chemical characteristic of this water. Different soil samples that were irrigated by sewage for different increasing periods were collected to investigate the changes in the soil texture as well as accumulation of heavy metals by the soils according to the period of irrigation (7, 12, 23, 40, 50 and 75 years). The overall results revealed that the longer period of irrigation demonstrated higher level of metal accumulation in the soil. The progressive increase of metals in the soil represents serious risk to the cultivated plant (as a food cycle). It is; therefore; recommended to decrease the level of heavy metals in sewage water via further simple wastewater treatment. For this purpose, a laboratory attempts were carried out to decrease the level of metals in the sewage water. Lime, as coagulant, and/or the dried leaves of Water Hyacinth plant were examined. Remarkable elimination of metals was demonstrated. It was also recommended to use the given sewage water for cultivating the woody or Lumber trees (for high economic revenue) to reduce any expected metal hazard in the food chain.