VOORHEES, N.J.--(BUSINESS WIRE)-- American Water Works Company, Inc. (NYSE:AWK), the largest publicly traded U.S. water and wastewater utility company, today presented the results of a study regarding pretreatment for desalination of seawater. Dr. Mark LeChevallier, Director of Innovation and Environmental Stewardship, reported the results at the 26th Annual WateReuse Symposium in Phoenix, Ariz.
Funded by the Water Research Foundation and the subsidiary companies of American Water, the study specifically concerned the removal of assimilable organic carbon (AOC) and total organic carbon during desalination pretreatment. Pretreatment for seawater desalination typically focuses on removal of particles but many of the problems with membrane fouling are due to natural organic matter in water. Some of the key findings of the study found that:
- Particles in seawater contained both positive and negative charges, which was unusual and doesn't occur in freshwater. These charges were due to the presence of certain minerals (calcium and magnesium) naturally present in seawater, which interferes with the removal of particles in water and explains why removal of natural organic matter in seawater is so difficult.
- Some common practices in seawater treatment (e.g., the addition of chlorine, or antifouling chemicals) can increase the levels of AOC and actually accelerate problems due to bacterial growth on the membranes.
American Water developed a novel method to measure the AOC that bacteria feed upon in order to grow on the desalination membrane filters. The test uses a naturally bioluminescent marine organism for the assessment and monitors its growth by tracking the increase in light produced by the bacterium.
“The results of these studies, suggest that when terrestrial organic matter enters highly saline water, it undergoes complexation by manganese and/or calcium to form soluble complexes that control its subsequent surface chemistry,” stated LeChevallier. “When absorbed onto silts, these complexes become difficult to remove by charge neutralization and may require separation by enmeshment requiring high coagulant doses or coagulation at extremes of pH that impact the surface charge and allow for removal.”
Along with LeChevallier, American Water’s Dr. Orren Schneider, senior environmental engineer, and Lauren Weinrich, senior research analyst, are co-authors of the paper highlighting the study. The presentation will be available on the WateReuse Association’s Web site, www.watereuse.org/association.
Presented by the WateReuse Association and cosponsored by the American Water Works Association and the Water Environment Federation, the WateReuse Symposium features more than 100 technical presentations, technical tours, a national legislative and water policy outlook session, receptions, an awards luncheon, and an exhibition.
The WateReuse Association is a nonprofit organization whose mission is to advance the beneficial and efficient uses of high-quality, locally produced, sustainable water sources for the betterment of society and the environment through advocacy, education and outreach, research, and membership.
About American Water
Founded in 1886, American Water is the largest publicly traded U.S. water and wastewater utility company. With headquarters in Voorhees, N.J., the company employs more than 7,000 dedicated professionals who provide drinking water, wastewater and other related services to approximately 15 million people in more than 30 states as well as parts of Canada. More information can be found at www.amwater.com.
In 2011, American Water is celebrating its 125th anniversary with a yearlong campaign to promote water efficiency and the importance of protecting water from source to tap. To learn more, visit www.amwater125.com.