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Published on: December 29, 2013
Microbial characterization and population changes in nonpotable reclaimed water distribution systems
Hodon Ryu1, Absar Alum, Morteza Abbaszadegan
1National Science Foundation Water Quality Center, Department of Civil and Environmental Engineering, Arizona State University, P.O. Box 875306, Tempe, Arizona 85287-5306, USA.
Environmental Science & Technology
|December 6, 2005
Summary
Microbial quality of nonpotable reclaimed water in the southwestern US showed Cryptosporidium and Giardia presence. Disinfection methods like UV light improved microbial indicator levels, but bacterial regrowth was linked to decreasing organic carbon.
Area of Science:
- Environmental Microbiology
- Water Quality Management
- Public Health
Background:
- Nonpotable reclaimed water is increasingly used in urban areas.
- Assessing microbial quality in distribution systems is crucial for public health.
- Pathogen and indicator organism monitoring informs treatment efficacy.
Purpose of the Study:
- To investigate microbial quality changes in nonpotable reclaimed water distribution systems.
- To evaluate the effectiveness of disinfection methods on microbial indicators.
- To understand factors influencing bacterial regrowth in reclaimed water.
Main Methods:
- Pathogen monitoring (Cryptosporidium, Giardia, enteroviruses).
- Microbial indicator analysis (total coliforms, fecal coliforms, coliphages).
- Assimilable Organic Carbon (AOC) measurement.
Main Results:
- Cryptosporidium (16%) and Giardia (43%) were detected; no infectious pathogens found.
- Coliform levels increased in distribution systems; UV disinfection reduced microbial indicators.
- AOC decreased by 3-fold, correlating inversely with bacterial regrowth.
Conclusions:
- Reclaimed water distribution systems can harbor protozoa.
- Chlorination alone may be insufficient; supplemental UV disinfection is beneficial.
- Reducing AOC is key to controlling bacterial regrowth in reclaimed water.
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