AwwaRF Target Topics
An AwwaRF e-newsletter on selected research topics
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AwwaRF on Water Quality
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VOLUME 4
ISSUE 6
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June 29, 2006
Five-Minute Interview: Paul Westerhoff on Organic Nitrogen
AwwaRF asked Paul Westerhoff, Ph.D, PE, of Arizona State University to discuss Organic Nitrogen in Drinking Water and Reclaimed Wastewater (order # 91116, project #2900). Westerhoff was principal investigator on this project, which sought to develop accurate dissolved organic nitrogen (DON) quantification methods and measure DON concentrations in raw and finished drinking waters and reclaimed wastewaters.
AwwaRF: Who should read this report and why?
Westerhoff: Utilities that have algae in their source water, or are influenced by upstream wastewater discharges would find the most interest in this report.
AwwaRF: Why is it so important that utilities be able to accurately measure DON?
Westerhoff: There have historically been techniques to measure organic carbon. While there is less organic nitrogen than organic carbon, the traditional Total Kjeldahl Nitrogen (TKN) method doesn’t have detection limits suitable for drinking water. TKN has been developed primarily for wastewater. So if you want to accurately understand the precursor material for nitrogenous disinfection by-products (DBPs), like nitrosamines and haloacetonitriles, they are all based on the amount of organic nitrogen you have. Traditionally, people have looked at organic carbon because of its relationship to trihalomethanes (THMs) and haloacetic acids (HAAs), but the organic nitrogen in influent has nitrogenous DBPs that are a potentially greater health concern.
AwwaRF: Based on your research, what steps can utilities take to properly remove DON?
Westerhoff: Processes that remove organic carbon do a pretty good job of removing organic nitrogen. Coagulation removes organic nitrogen. But biofiltration can actually produce some organic nitrogen, as inorganic nitrogen in the water gets converted to organic nitrogen. So utilities with biofiltration need to think about whether they’re actually producing organic nitrogen.
AwwaRF: In your view, what is the next logical step in organic nitrogen-related research?
Westerhoff: AwwaRF has already started taking the next steps. This was an unsolicited project, and it was followed up by two other AwwaRF projects: A draft report has already been submitted for "Contribution of Wastewater to DBP Formation" (project #2948), and "Occurrence and Formation of Nitrogenous Disinfection By-Products" (project #3014) started up about nine months ago.
In 2006, another unsolicited project ["Organic Chloramine Formation in Water Distribution Systems and Influence on Disinfection Efficiacy and Nitrification" (project #4065)] was selected for funding to investigate the formation of organic chloramines, a topic initially investigated under project 2900.
AwwaRF: What is the single, most important point that you would like readers to take away from this report?
Westerhoff: Utilities need to know that pretty much all waters have organic nitrogen, and the ratio of organic carbon to organic nitrogen is 10:1.
AwwaRF: What else do you think readers might want to know about the report?
Westerhoff: The project was intended to focus on how to measure organic nitrogen and initiate studies on its removal at 28 full-scale water treatment plants and in laboratory jar tests with alum or nitrogen-containing cationic polymers. We also started to investigate reactions between organic nitrogen and disinfectants to form nitrogenous disinfection by-products and organic chloramines.
As an unsolicited project, our focus wasn’t necessarily on utilities, but we did survey 28 water treatment plants and found that organic nitrogen was removed during water treatment. We also found that there are seasonal variations in organic nitrogen concentrations as a function of factors like algae growth.
[PRINTER FRIENDLY VERSION]
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Awwa Research Foundation
Copyright © 2006 Awwa Research Foundation . All rights reserved.
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The Awwa Research Foundation is a member-supported, international, nonprofit organization that sponsors research to enable water utilities, public health agencies, and other professionals to provide safe and affordable drinking water to consumers.
Awwa Research Foundation, 6666 W. Quincy Ave., Denver, CO 80235, USA. Telephone: 303.347.6100, Web: www.awwarf.org, E-mail: info@awwarf.org.
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