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Innovative Biological Water Treatment for the Removal of Elevated Ammonia
Lytle, D. A., C. White, D. Williams, L. Koch, AND E. Nauman. Innovative Biological Water Treatment for the Removal of Elevated Ammonia. Journal AWWA. American Water Works Association, Denver, CO, 105(9):E524-E539, (2013).
The objective of this work was to demonstrate the effectiveness of an innovative and simple biological water treatment approach to remove more than 3 mg N/L ammonia and iron from the water through a pilot study conducted at a water utility in Iowa. The study also identified operating parameters necessary to meet the desired goal of complete ammonia and iron removal, and discuss the design of a full-scale system with the same goals. Study results will benefit a range of systems across the United States by providing guidance on the design and operation of biological treatment systems for ammonia removal.
The objective of this work was to demonstrate the effectiveness of an innovative and simple biological water treatment approach for removing 3.3 mg N/L ammonia and iron from water using a pilot study conducted at a utility in Iowa. Biological water treatment can be an effective approach to addressing low ammonia levels, however, providing adequate oxygen to address source water ammonia levels greater than 1.5 mg N/L is challenging. The treatment consisted of a biological “contactor” combined with aeration, followed in series with a dual granular media. Orthophosphate was necessary to satisfy biological nutrient requirements and maintaining near-saturated dissolved oxygen levels throughout the contactor was important. The pilot demonstrated that a contactor and filter operated at loading rates of 2.2 gpm/ft2 and 2.0 gpm/ft2, respectively, met desired finished water quality objectives. The contactor alone was able to completely biologically oxidize all of the ammonia to nitrate. Contactor maintenance was minimal.