AWWA WQTC64029

The Township of Sparta, New Jersey has detected uranium at concentrations above the Maximum ContainmentLevel (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 anaverage of 300 mg/L as CaCO3. The wells contain radon at 50,000 pCi/L and under a previous project apacked tower aeration system was installed that removes the radon to less than 100 pCi/L. The combinedradium 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 usingthese wells. The Township prepared a treatability study to investigate feasible, cost effective options. Acritical factor in the evaluation was residuals minimization as there are no sewers in the vicinity of thesite. The space available for uranium treatment is limited by the site conditions and at most, a 300 squarefoot addition to the existing facilities would be allowed.Three treatment processes were evaluated: reverse osmosis (RO); conventional anion exchange with onsiteregeneration; and, a proprietary anion exchange based adsorptive media supplied by WRT. ROand conventional anion exchange were rejected due to the large volume of residuals that are generatedand the lack of space is available for reduction of residuals through additional treatment. The WRTsystem was selected as the best option as it does not generate residuals on a daily basis. The WRT systemis not backwashed or regenerated on site. The WRT system is operated until the treated water uraniumlevel reaches approximately 15 ppb (1/2 the MCL) at which time the media is removed and disposed ofby 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 wasneeded to verify the performance of the WRT system and to determine the media changeout frequency. Apilot test was performed for 117 days beginning in July 2005. The pilot unit consisted of two columns inseries. The raw water uranium varied between 81 and 106 ppb. The uranium concentration remained lessthan 20 ppb at the effluent from the 1st column for 90 days. The uranium concentration from the 2ndcolumn, which is the treated water outlet, began at 0.7 ppb, and at the end of the 117 period the uraniumconcentration was 5.5 ppb. Gross alpha was also measured during the study and similar removals wereachieved. Based on the pilot results, the predicted media replacement frequency will be approximatelyonce 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 operatorrequirements during the testing, the cost of the pilot including laboratory services, and the involvement ofthe state regulatory authority. Includes tables, figures.

Product Details

Edition:

Vol. - No.

Published:

11/01/2006

Number of Pages:

19

File Size:

1 file , 410 KB