Reuse possibility of the Izmir wastewater treatment plant effluent in Menemen Plain irrigation - A case study of Turkey

Abstract

Agricultural reuse of treated and raw wastewaters offers an additional resource of irrigation water and high soil fertilizing potential. With the industrial development and urban construction in Izmir City, Turkey, which has mostly semi-arid region, the water potential is low; on the other hand, rapidly growing population causes an increase in water demand. The present work reports of one year of Izmir municipal wastewater effluents constituents and evaluates the potential use of the effluent wastewater for the Menemen Plain. A significant variability of the effluent quality exists in the wastewater treatment plant along the year due to the rainfall and creeks, flowing into the sewerage system. Total average concentrations of nitrogen and phosphorous in the effluent water were about 7.2 mg N/L (5.02-11.0 mg N/L) and 3.5 mg P/L (2.85-4.8 mg P/L), respectively, through the irrigation season. If the treated water is used for irrigation, totally, about 20 kg N, 9.45 Kg P, and 0.2 kg Zn, 4x10(3-) Kg Cd, and 0.015 Kg Fe/ha will be applied in the Menemen Plain during, the irrigation season. The effluent water can be used for irrigation of moderately sensitive and tolerant crops considering boron concentration. The total chloride and sodium concentrations of the effluent were higher (between 150-627 mg Na/L and 310-2469 mg Cl/L) than that of the water supply. The electrical conductivity (EC) values of the effluent ranged between 1000-7000 mu S/cm (average 2966 mu S/cm), which was higher than 2000 mu S/cm (2 dS/m) recommended for treated wastewater to be used for agricultural purposes. Sodium adsorption ratio (SAR) (about 9.5) and EC values (2966 mu s/cm), indicate the highest restriction in use of the treated water for irrigation.