Removal of nitrogen and phosphorus compounds in biological treatment of municipal wastewater in Israel

In Israel, the water shortage, on the one hand, and the concern for wa ter resource quality on the other, have led to the awareness that a national wastewater reclamation program must be developed. Such a program could cover a major part of the agricultural water demand, and may enable disposal of effluents without any health hazard or environmental nuisance. Recent regulations issued by the Ministry of the Environment and by The Water Commission require stringent quality standards for treated wastewater destined for agricultural irrigation or for disposal into rivers. These include the requirement to apply processes for nitrogen removal (nitrification- denitrification) and for phosphorus removal. In Israel, there is only limited experience in the application of biological wastewater treatment processes for nitrification and denitrification. Treatment plants designed for nitrogen removal (such as the Shafdan and Netanya treatment plants) have demonstrated partial success only. Moreover, the requirement for phosphorus removal has not been studied or applied in Israel. It is therefore necessary to study and develop proper guidelines for nitrogen and phosphorus removal for municipal wastewater treatment in Israel. Pioneering results supported by a sophisticated mathematical model were obtained in this study. It has been shown that N and P removal can be easily achieved in Activated Sludge systems if designed and operated properly. Interpretation of results and their analysis for design purposes require the use of a mathematical model.