AWWA ACE63049

The effects of possible nutrient limitation and disinfectants on Legionella pneumophilaand Mycobacterium avium complex (MAC) regrowth in domestic water heaters are ofhigh interest. When an initial disinfectant residual of at least 0.25 mg/L chlorine or 0.40mg/L monochloramine is maintained, no detectable regrowth occurred in glass reactorswithout extensive sediment present at 37º C. In the nutrient concentration range typicallyencountered in domestic water supplies, high levels of microbes always grew onLegionella and frequently on Mycobacterium media. This points to inherent problems inmaintaining microbial purity of water in domestic water heaters without disinfectant, andpoints to the importance of other important physical control factors such as temperature.However, many nutrients markedly increased growth of microbes, including the freeammonia that forms after chloramine (chlorine combined with free ammonia) decays.Use of chloramine disinfectant can sometimes worsen regrowth of microbes in situationswhere chlorine has completely decayed relative to the situation when free chlorine hascompletely decayed. Includes 18 references, table, figures.

Product Details

Edition:

Vol. - No.

Published:

06/01/2006

Number of Pages:

7

File Size:

1 file , 290 KB