The North Texas Municipal Water District (NTMWD) began using ozone as the primary disinfectant at its Wylie Water Treatment Plants in 2014. As a result of the $123 million ozone project, a significant improvement in the taste and odor of the drinking water produced is expected. The NTMWD selected ozone in the treatment process because of changes in US Environmental Protection Agency’s Safe Drinking Water Act.
Now operating the nation’s largest water treatment facility using ozone, the NTMWD implemented extensive planning efforts, modifications, construction and project management at the four Wylie Water Treatment Plants. In addition to the Wylie location, the Bonham and Tawakoni Water Treatment Plants also produce ozonated water. Cumulatively, NTMWD has the capability to treat and deliver 806 million gallons per day of high- quality, safe drinking water to the region served.
Ozone is a good choice for municipal drinking water treatment because it offers multiple benefits to the plant operators. In the case of NTMWD, it allowed them to meet more stringent US EPA regulations for disinfecting drinking water while also improving the waters taste and odor profile. Using another primary disinfectant would have required a second process or chemical to deal with the taste and odor.
Burleson, TX residents are having taste and odor problems with their drinking water which is purchased from Fort Worth. While the water has been determined to be safe to drink, officials have acknowledged that it does have an “earthy smell and taste”.
Tests indicated an increase in the levels of a substance called geosmin in Lake.
Geosmin is a type of bicyclic alcohol produced by actinobacteria and released when those organisms die. City officials have said that colder-than-usual temperatures in December and January killed off the actinobacteria and released the geosmin into Lake Benbrook. Geosmin levels there are the highest seen in years.
Fort Worth uses ozone as a primary disinfectant which has the side benefit of removing taste and odor compounds like geosmin from the water. To combat the increased level of geosmin, the water department has increased the dose of ozone injected into the water. In addition city has also started blending the water from Lake Benbrook with water from Cedar Creek Lake.
Many factors such as seasonal variations and weather can result in changes in the level of taste and odor compounds in surface water sources such as lakes an reservoirs. It is difficult to predict these changes and develop counter measures. Ozone has been found to be one of the more effective and economical agents for this purpose since it not only removes the taste and odor compounds, but also disinfects the water.
The Fort Worth Business Press reports that Water from Fort Worth’s Rolling Hills and Westside water treatment plants is safe to drink despite changes in taste and odor, according to city officials. Both water departments assure their customers the water is safe for drinking, cooking, bathing and all other purposes, though it has what Fort Worth officials call an “earthy smell and taste.”
Water quality data from the district indicated that levels of geosmin have been steadily rising in recent months, according to a Fort Worth news release. Geosmin can produce taste and odor issues in the part per billion range, so the amounts found in the water are incredibly small. Fort Worth water officials describe that as a normal occurrence for this time of year. Geosmin is a naturally occurring compound produced by bacteria in soil and algae found in surface water. Cold temperatures kill off algae in surface water, and the dead algae release the geosmin.
Fort Worth and Arlington have increased the dosage of ozone at their treatment plants. Ozone is used to disinfect the drinking water, and it can help with resolving taste and odor issues, but not in all cases. The key parameter is the ozone dose. Since the amount of geosmin varies from year to year, adjusting the ozone dose to match the amount of geosmin in the water requires time. The ozone react with the molecule to change its characteristics such that it does not affect the taste of the water.
MONROE — Monroe is updating it ozone system to control potential taste-and-odor problems with replacement one of two ozone generators for a cost of nearly $1,000,000. The new ozone generator is to become operational by Aug. 15. The ozone generators were installed in 1997 and 2001, but the 1997 ozone generator has failed and is being replaced with a larger generator. Design modifications will allow the Monroe to eventually install a third ozone generator to help increase the plant’s treatment capacity.
Monroe is Michigan’s only city to draw its water from Western Lake Erie. The main part of the water plant opened on March 1, 1924. Toledo and Port Clinton also draw their water from the shallow western basin.
Injecting ozone into the water after it’s been pulled from the lake is part of Monroe’s first-treatment process to improve taste and remove odors. The plant’s ozone capacity also is being increased to help fend off toxins found in western Lake Erie’s most prevalent form of harmful blue-green algae, microcystis. The main toxin in that algae is called microcystin.
One of Lake Erie’s worst algae outbreaks occurred this summer. It wasn’t as large as the record 2011 bloom. But the toxin was so concentrated in the Oak Harbor area that it overwhelmed a water-treatment system that serves 2,000 residents of Ottawa County’s Carroll Township. That event was the first in Ohio history to cause an emergency closure of a water plant because of algae toxins. Residents were provided bottled water until the township was able to get uncontaminated tap water from Port Clinton. The township flushed out its system and put its plant back into service after the threat subsided.
Big Bend Water District (BBWD) is the supplier of potable water to the community of Laughlin, the sole source of which is the Colorado River. “The BBWD has over 15,000 acre feet per year as an allotment, but historically Laughlin rarely uses more than 5,000 acre feet of that allotment. BBWD can treat a maximum of 15 million gallons per day. Over a 12-month period, the average per-day flow through the treatment plant is three to four million gallons a day. Intake for the BBWD is located in the Colorado River just north of the Laughlin Bridge; most of the water in the river is a result of snow melt in the Rocky Mountains.
The job of the treatment plant is to remove impurities from the water and make it safe for drinking. The BBWD uses ozone as a disinfectant at the facility. Ozone is generated on-site and prevents the formation TTHMs, which the EPA limits in water.
Trihalomethane – or TTHM – is a by-product of chlorine, when it is used to disinfect drinking water. Ozone can remove some of the precursor compounds that form TTHM and reduces the total amount of chlorine that can form them. While more expensive to generate than other oxidants the tradeoff is a lot less taste and odor issues and much lower TTHMs. BBWD treats with chlorine, the EPA requires the district to maintain a disinfectant residual in the system because it is a surface water system.
During the 64th Annual U.P. Water Treatment System Operator’s Training, which is associated with the American Water Works Association. Manistique competed against 11 other communities in a drinking water taste off. Manistique’s water supply is drawn from the Indian River – something which sets Manistique apart form many of the other communities in the taste competition. It’s very hard for a surface water treatment plant to compete against groundwater systems. Manistique is the first surface water plant to win the competition in the U.P.
Last year the city upgraded it’s water treatment plant to use ozone and granular activated carbon filtration in order to meet new drinking water quality rules making it the first in the U.P. One of the primary uses for ozone water treatment is taste and odor improvement. What makes ozone especially attractive for this application is that it can simultaneously improve water taste while also imrpoving disinfection and removing other water impurities. This is the case in Manistique.
Salt lake City uses ozone at two of its facilities: Little Cottonwood (LCW) and Point of the Mountain (POM). LCW has Utah’s first and largest ozone drinking water treatment system, two ozone generators each sized at 3,750 lb/day of ozone. The facility can treat 143 MGD of water. The plant can dose ozone at 3.5 ppm during times when taste and odor control are required or as low as 1 ppm during normal operation. The ozone provide a 0.5 log reduction of Giardia. the system became operational in 2009.
The new POM plant can produce up to 950 lbs/day of ozone delivering an ozone dose of 3 ppm. It is capable of treating 70 MGD. This system also employs a UV disinfection system down stream of the ozone to allow achievement of the LC2ESWT rule as well as stage 2 disinfectants/disinfection byproducts rule. POM thus has a multi-barrier treatment system with complementary technologies.
Both of the improvement projects were part of a $250 MM capital program. The improvements now allow Salt Lake City to meet future regulations while providing its customers with high quality good tasting water. The large financial commitment illustrates the foresight of the water districts leadership.
The city of Lawrence is researching new treatment methods to deal with a taste and odor problem associated with its drinking water which recently have become a more serious issue.
The city’s Utility Department said there is a solution in the works that would use “advanced oxidation” to combat taste and odor issues that are being caused by a by-product of algae. The new process essentially would produce ozone oxidize the by product of algae decomposition, e.g. MIB or geosmin.
The master plan estimates it would cost about $18 million to add the oxidation process to the city’s two water treatment plants. Currently, the city uses carbon powder to treat the water, but it hasn’t been very effective in controlling taste and odor issues related to the most recent geosmin outbreak. Geosmin, a by-product of dead algae, doesn’t pose a health risk to humans or pets, but city officials concede the taste and odor are unpleasant.
Norman water treatment plant improvements enter Phase II: The city council, acting as the Norman Utilities Authority, will consider approving a $1.5 million contract with Carollo Engineers for Phase II improvements at the water treatment plant located in northeast Norman. The improvements follow studies conducted in 2006 and 2007. Carollo performed a chlorine pilot study, an ozone pilot study and a detailed electrical evaluation, according to city staff reports.
The first phase rehabilitated the electrical infrastructure “to allow the future installation of an ozone unit to be used as a primary disinfectant and to control taste and odor,” according to staff reports. Capacity was increased from 14 to 17 million gallons per day, and other equipment was upgraded, including the installation of a new solids contact clarifier, replacement of the filter media and replacement of lime feed and carbon dioxide systems.
Phase II will include an eight-month ozone pilot test, a Hydrologic Engineering Center River Analysis System study of the creek located on site and design services. This water treatment plant project addresses the city’s drinking water needs at the plant located in north east Norman.
The Otter Lake Water Commission has submitted is plan, as well as a loan application for nearly $2 million, to the Illinois Environmental Protection Agency (IEPA) public water supply loan program. The Otter Lake commission is responsible for water treatment and for the distribution systems that transmit water to 467 individual and nine wholesale customers in an area that includes Auburn, Divernon, Girard, Pawnee, Thayer, Nilwood, Glenarm, Tovey, South Palmyra Rural Water District, Henderson Rural Water District and rural customers.
The commission in 2010 completed a $6 million expansion to the water treatment plant on the east side of Otter Lake just west of Girard, IL. The additional money will allow the plant to meet a new requirement for the cryptosporidium parasite that will require additional treatment. The microscopic parasite can cause diarrhea and more severe complications, particularly in children or people with immune-system disorders.
The commission had engineering studies done to determine the most cost-effective way of removing the parasite, as well as controlling taste and odor. Based on those evaluations, an ultraviolet light system with advanced oxidation process was selected.
The project is scheduled for completion by October 2013.