You are here:
Consequences and Reduction of Elevated Ammonia in Illinois Groundwaters: U.S. EPA Research Efforts
Citation:
LYTLE, D. A., D. Williams, C. MUHLEN, B. ALMASSALKHI, AND C. P. WHITE. Consequences and Reduction of Elevated Ammonia in Illinois Groundwaters: U.S. EPA Research Efforts. Presented at 2009 Illinois Section AWWA, Springfield, IL, March 16 - 19, 2009.
Impact/Purpose:
To inform the public
Description:
Nitrification in drinking water distribution systems is a concern of many drinking water systems. Although chloramination as a source of nitrification has drawn the most attention, many source waters contain significant levels of ammonia, particularly in Midwestern States such as Illinois. Aside from taste and odor complaints often accompanying nitrification, more potentially concerning is the formation of nitrite and nitrate in the distribution system, both of which have MCLs of 1 mg/L NO2-N and 10 mg/L NO3-N, respectively. These contaminants are only regulated at the point of entry into the distribution system, not at the consumer’s tap. Given the potential impacts of nitrification, a clear need to monitor ammonia, nitrate and nitrate in drinking water distribution systems exists. Furthermore, given the likelihood that nitrification problems do regularly exist in systems that use sources waters having elevated ammonia levels, simple treatment options for source water ammonia reduction are needed. The first objective of this work was to monitor and report ammonia, nitrite, and nitrate (and other water quality parameters) levels in drinking waters from the distribution systems of four drinking water utilities in Illinois that have elevated free ammonia entering their distribution systems. Secondly, U.S. EPA work conducted in Illinois and Ohio on biological treatment to reduce source water ammonia will be presented. The four Illinois test communities had free ammonia levels entering their distribution systems between 2.9 to 10.1 mg/L NH3-N. Distribution system nitrite levels were as high as 3.5 mg/L NO2-N, and many values were greater than 1 mg/L NO2-N. Nitrite levels generally increased with distance away from the treatment plant. Nitrate levels were observed between 0 to 2.8 mg/L NO3-N, and the highest values were noted at sites in the mid to far distance range of the distribution systems. Locations with greatest nitrite levels tended to have little to no total chlorine present. Community awareness of the nitrification problems prompted test sites to take action which included optimizing ion exchange softening regeneration frequency for ammonia removal, increasing chlorine addition and improving distribution system maintenance (e.g., flushing) programs and will be briefly discussed. Pilot scale testing at several locations has shown that the oxidation of source water ammonia by biological filtration can be used to reduce or eliminate free ammonia that enters the distribution system. The impact of water quality factors and operating parameters including oxygen, pH, TOC and filter loading rate on ammonia oxidation effectiveness will be discussed.
