Full Description

This paper reports on pilot tests of nitrification control methods for Tucson Water (Tucson, Arizona),Mohawk Valley Water Authority (MVWA, Utica, New York) and Birmingham Water Works and SewageBoard (Birmingham, Alabama). Flow-through pilot units were used in each city to simulate plug flowconditions and the average detention time in each distribution system. The pilot units were highlyeffective in showcasing the development of nitrification and the effectiveness of different controlstrategies. Cultures of ammonia oxidizing bacteria (AOB) were acclimated in each utility's water andadded to each unit to encourage nitrification in the pilot tests. Chloramine degradation, ammonia release,and nitrification were quantified in each unit using a combination of traditional and innovative chemicaland microbiological methods. The onset of nitrification in each system varied significantly in thedifferent water qualities. All three systems, however, were shown to be susceptible to nitrification andwill require an effective nitrification control strategy.Nitrification control methods tested include higher chloramine ratios and doses, continuous application ofchlorite ion at various doses, and intermittent chlorite ion addition. Higher chloramine doses (2.5 mg/Land 4.0 mg/L total chloramines) and ratios (5:1 rather than 3:1 Cl2:NH3-N) delayed nitrification in Tucsonand MVWA but were not preventative, as these techniques proved to be in Birmingham. Continuousapplication of a low dose of chlorite ion (0.1 to 0.2 mg/L) prevented nitrification in all three pilot tests.Intermittent addition of chlorite ion was effective in all three systems, although pilot tests showed that thisstrategy would be most successful if used to prevent nitrification rather than control advancednitrification.Lessons learned and contrasts observed in the three parallel pilot tests are discussed, and the paper also addresses implications for full-scale systems, including new monitoring techniques and cost estimatesof nitrification control strategies. Includes 9 references, tables, figures.

Product Details

Edition: Vol. - No. Published: 11/01/2005 Number of Pages: 18File Size: 1 file , 640 KB