Assessment of waste waters quality for irrigation purposes

Reuse of wastewaters for irrigation purposes represents an additional source of those available to overcome the gap in quantity of irrigation water in Egypt. Such a gap is expected to increase after construction of Renaissance Dam in Ethiopia. However, evaluation of suitability of these waste waters for irrigation should be a matter of concern and should be carried out periodically owing to the variations of amounts and types of contaminants disposed in these waters. Therefore, the current investigation is a case study on waste water samples taken from inlets and outlets of Arab Abo-Saed, El-Gabal El-Asfer, Abo-Rawash and El-Berka treatment plants. These waters were analyzed for pH, total suspended solids (TSS), electrical conductivity (EC), soluble ion contents, heavy metal contents (Cd, Ni and Pb), boron content (B),.Also, NH₄-N and NO₃-N,  biological oxygen demand (BOD₅) and chemical oxygen demand (COD) beside of total coliform were determined. Evaluation of the investigated waste waters was executed through determining of the hydrogen ion activity, salinity hazards, sodium hazards and miscellaneous hazards.  All the investigated waste waters were of high salinity, low sodicity  and very minute contents of the heavy metals and boron and hence can be used for irrigation after taking into account the leaching requirements and type of the crop to be irrigated. However, total coliform bacteria exceeded the permissible limits and more efficient treatment should be followed to protect human health against these bacterial contaminants.