AWWA WQTC62531

The District of Columbia Water and Sewer Authority (DCWASA) purchases anddistributes chloraminated water to over 120,000 residences, businesses, and governmentalbuildings. Nitrification, the conversion of ammonia to nitrite and nitrate, is a concernfor chloraminated systems. This paper describes relationships between multiple waterquality parameters and nitrite formation in the WASA distribution system.In November 2000, the disinfection changed from free chlorine to chloramines. In 2003,DCWASA experienced increased lead levels due to the change in water chemistry,particularly the oxidation potential of the water. In 2004, orthophosphate was added atthe treatment plants for corrosion control. Since the disinfectant change in 2000, theAqueduct (DCWASA's wholesaler) switched disinfection from chloramines to freechlorine, or "chlorine burn," in the spring each year. Concerned for the effects on leadcorrosion, the Aqueduct, DCWASA, and other purchasing utilities agreed to not performa chlorine burn in 2005.Nitrification is a concern for chloraminated systems and without a chlorine burn, itbecame a primary concern for the summer months. DCWASA analyzed water qualitydata to identify indicators for nitrification and develop operational control levels.DCWASA was also aware of a school where nitrification occurred the previousNovember. DCWASA closely monitored this site and once nitrification started,researched the effects of flushing. This paper describes the data analysis conducted toidentify nitrification indicators and their warning and action levels. Includes 3 references, figures.

Product Details

Edition:

Vol. - No.

Published:

11/01/2005

Number of Pages:

9

File Size:

1 file , 280 KB