AWWA WQTC64029

The Township of Sparta, New Jersey has detected uranium at concentrations above the Maximum Containment Level (MCL) in their Autumn Hill Well Nos.1 and 2. The wells have a combined capacity of 130 gpm. The initial uranium concentration at the wells was 122 µg/L. The wells have moderate hardness with an average of 300 mg/L as CaCO3. The wells contain radon at 50,000 pCi/L and under a previous project a packed tower aeration system was installed that removes the radon to less than 100 pCi/L. The combined radium 226/228 level is approximately 1.5 pCi/L, which is well under the 5.0 pCi/L MCL. This water source is a valuable asset and treatment for uranium is necessary in order to continue using these wells. The Township prepared a treatability study to investigate feasible, cost effective options. A critical factor in the evaluation was residuals minimization as there are no sewers in the vicinity of the site. The space available for uranium treatment is limited by the site conditions and at most, a 300 square foot addition to the existing facilities would be allowed. Three treatment processes were evaluated: reverse osmosis (RO); conventional anion exchange with onsite regeneration; and, a proprietary anion exchange based adsorptive media supplied by WRT. RO and conventional anion exchange were rejected due to the large volume of residuals that are generated and the lack of space is available for reduction of residuals through additional treatment. The WRT system was selected as the best option as it does not generate residuals on a daily basis. The WRT system is not backwashed or regenerated on site. The WRT system is operated until the treated water uranium level reaches approximately 15 ppb (1/2 the MCL) at which time the media is removed and disposed of by WRT at a licensed facility, and new media is installed. There are no operating uranium removal systems on drinking water in New Jersey and a pilot test was needed to verify the performance of the WRT system and to determine the media changeout frequency. A pilot test was performed for 117 days beginning in July 2005. The pilot unit consisted of two columns in series. The raw water uranium varied between 81 and 106 ppb. The uranium concentration remained less than 20 ppb at the effluent from the 1st column for 90 days. The uranium concentration from the 2nd column, which is the treated water outlet, began at 0.7 ppb, and at the end of the 117 period the uranium concentration was 5.5 ppb. Gross alpha was also measured during the study and similar removals were achieved. Based on the pilot results, the predicted media replacement frequency will be approximately once every two years. The Township will commence design of the system in 2006. This paper focuses on the pilot study and includes a discussion of the operator requirements during the testing, the cost of the pilot including laboratory services, and the involvement of the state regulatory authority. Includes tables, figures.