Nitrogen and Phosphorus Removal from Saline Wastewater Using Up-flow Sludge Blanket Filtration Process

There is recent trend of providing additional treatment of wastewater beyond tertiary level. The purpose is to refine water to a quality that is safe for reuse for unrestricted irrigation and other non potable uses. For this purpose Kuwait has built and operated an advanced wastewater treatment plant with present capacity of 500,000 m/d. This plant providing treatment beyond tertiary utilizes the process of ultra filtration (UF) and reverse osmosis (RO). The reject water of this unit contains high concentration of total nitrogen and total phosphate. Safe disposal of this water into the environment or possible reuse needs substantial reduction of these chemicals. In this study, a bench scale up-flow sludge blanket filtration system was investigated to treat a synthetic saline wastewater rich in nitrogen and phosphorus compounds. The system operated with an average hydraulic-retention time (HRT) of 19 h whereas, sludge age varied within the range of 14 to 16.5 d. The results show that the average removal efficiencies of the system for biological oxygen demand (BOD), chemical oxygen demand (COD) were over 86%, and 82%, respectively. The phosphate and nitrogen average removal were found to be 50% and 45% respectively.