Ammonia What Every Operator Should Know Why should you look for ammonia? Additional Reading Ammonia is not commonly measured in drinking water despite potentially being problematic in your source Brandhuber, P.J. (2012). What’s your water, especially in groundwater. It can create a large chlorine demand, as the ammonia is converted ammonia IQ? Opflow, 38(4): 12-14. Blute, N., Ghosh, A., and Lytle, D. (2012). to nitrogen gas and the chlorine becomes chloride. Depending on the amount of chlorine added, it is Assess ammonia treatment options. possible for the combination of the two to form chloramines by accident which can then increase the risk Opflow, 38(5): 14-17. for nitrification and biofilm growth in the distribution system. Some systems have seen such a dramatic Henrie, T., Rezania, L.W., Nagy, D., and Lytle, D. (2012). Got ammonia? Opflow, pH drop due to nitrification that it has resulted in lead and copper corrosion. 38(6): 22-24. Guidelines for Canadian Drinking Water Quality: Guideline Technical Document— Testing for ammonia is recommended if you have any of the following Ammonia (2013) available at: http://www. hc-sc.gc.ca/ewh-semt/pubs/water-eau/ issues in groundwater or in your distribution system: ammonia-ammoni/index-eng.php#a4.1 ➤ ➤ Douglas, I., Guthmann, J., Muylwyk, Difficulty achieving or maintaining a free Drop in distribution system pH Q. and Snoeyink, V. (2004). Corrosion chlorine residual ➤ Copper or lead corrosion issues in control in the City of Ottawa—Comparison of alternatives and case study for lead ➤ Iron or manganese the distribution system reduction in drinking water. In: Robertson, W. and Brooks, T. (Ed.). 11th Canadian ➤ Color ➤ Nitrification-related symptoms in National Drinking Water Conference and ➤ the distribution system Second Policy Forum. Calgary, Alberta, Hydrogen sulfide (H2S—rotten egg odor) Canada. April 3–6. ➤ Difficulty achieving or maintaining a free Edwards, M. and Dudi, A. (2004). Role of chlorine residual chlorine and chloramine in corrosion of lead-bearing plumbing materials. J. Am. Water Works Assoc., 96(10): 69–81. You can send samples to a laboratory (Standard Method 4500 NH3), or you can use a portable test kit. Testing for total organic carbon and methane is also recommended, since these compounds frequently Zhang, Y., Groiffin, A. and Edwards, M. (2008). Nitrification in premise plumbing: co-occur. Keep in mind that methane can build up in the headspace of tanks and create an explosion risk. role of phosphate, pH, and pipe corrosion. Environ. Sci. Technol., 42(12): 4280–4284. Zhang, Y., Edwards, M., Pinto, A., Love, N., Ammonia Treatment Camper, A., Rahman, M. and Baribeau, H. Three of the most common options for treatment are discussed in the following table. In addition to those (2010). Effect of nitrification on corrosion in the distribution system. American Water options reverse osmosis, ion exchange and air stripping with pH adjustment may be appropriate in some Works Association Research Foundation applications. For air stripping to be viable the pH needs to be adjusted to 11, which may not be cost and American Water Works Association, Denver, Colorado. effective for hard water. Treatment Type Details Important Considerations BREAKPOINT The idea here is to add enough chlorine to convert all of It requires 8 to 12 mg/L of chlorine for every 1 mg/L of ammonia to CHLORINATION the ammonia to nitrogen gas. The chlorine is converted complete the reaction. Applying high doses of chlorine can lead to to chloride. Additional chlorine is added to maintain a disinfection byproduct formation. free chlorine residual in the distribution system. Competition from other chlorine demanding compounds (i.e. Fe, Mn, H2S, TOC) will drive up required chlorine dosage even higher. CHLORAMINATION If you have naturally occurring ammonia at about 0.5 If you have color due to organics (e.g. total organic carbon or TOC) or mg N/L or less, you may be able to add chlorine to hydrogen sulfide (H2S), then this may not be the best option. You will still form chloramines. have color and odor issues after chlorine addition. BIOLOGICAL Microbes use oxygen to convert ammonia to nitrite In order to achieve biological removal of ammonia, you need to have water OXIDATION and then into nitrate. This is called nitrification. While with adequate dissolved oxygen. The process can lower the pH, and does nitrification is typically discouraged in distribution use the dissolved oxygen. systems, this process encourages nitrification in Need a reactor vessel/pressure vessel for the biological growth to remain as the treatment plant to avoid subsequent impacts on an attached growth process. disinfection. www.awwa.org.