Comparing Chlorination and Chloramination for Controlling Bacterial Regrowth

Abstract

The Greater Vancouver (B.C.) Water District compared chlorine and chloramine as secondary disinfectants and their effects on bacterial regrowth in a distribution system supplied with disinfected, unfiltered surface water. The selected section of the distribution system was divided into three areas: a control area that received no secondary disinfectant, an area that received free chlorine as the secondary disinfectant, and an area that received chloramine. Water samples were analyzed for chlorine residual, coliform bacteria, heterotrophic plate count (HPC) bacteria, and turbidity. Although both chlorine and chloramine were effective in reducing bacterial growth in the distribution system, chloraminated water had a lower HPC, less taste and odor, fewer positive coliforms, and a more stable residual.

Influencing factors in the occurrence of injured coliforms in the drinking water distribution system in the city of La Plata, Argentina

“…These results are in agreement with those obtained by Neden et al (1992) and LeChevallier et al (1996), who also correlated the occurrence of coliforms with high temperatures. The highest number of coliforms was obtained in summer for both systems, suggesting that temperature is clearly a factor related to bacterial regrowth.…”

Selection Criteria for Water Disinfection Techniques in Agricultural Practices

“…This is especially the case with UV, as many microorganisms possess the ability to repair DNA damage by light-independent (i.e., dark repair) as well as light-dependent enzymatic mechanisms (Sanz et al, 2007;Locas et al, 2008). Regarding fresh produce practices, this is of particular concern when disinfected water is stored before use and can be avoided by maintaining a small disinfectant residual of a relatively stable disinfectant like monochloramine, or the less stable chlorine and chlorine dioxide (Neden et al, 1992;Momba et al, 1998Momba et al, , 2003USEPA, 1999a).…”

Redox gradients in distribution systems influence water quality, corrosion, and microbial ecology

“…These disinfectants can dissipate (i.e., decay) with increasing water age, resulting in lower residual disinfectant in distal parts of the distribution system (Lu et al, 1995;DiGiano et al, 2005). However, compared to chlorine, chloramines form fewer regulated disinfectant by-products and are generally more persistent in the distribution system (Neden et al, 1992;Norton and LeChevallier, 1997). Chloramines have also been reported to be more effective than free chlorine at reducing heterotrophic plate counts (HPC) in drinking water systems (Neden et al, 1992).…”

“…However, compared to chlorine, chloramines form fewer regulated disinfectant by-products and are generally more persistent in the distribution system (Neden et al, 1992;Norton and LeChevallier, 1997). Chloramines have also been reported to be more effective than free chlorine at reducing heterotrophic plate counts (HPC) in drinking water systems (Neden et al, 1992). For all of these reasons the use of chloramines as a disinfectant has increased in recent years at U.S. water utilities (Seidel et al, 2005;Nguyen et al, 2011).…”