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.
Denton was a top-5 finalist in the U.S. Conference of Mayors’ 2011 “Best Tasting City Water in America” contest, and the state of Texas recently awarded Denton with “superior” water status.
Denton has two separate water treatment facilities that meet the demands of almost 120,000 residents. The first stage of the treatment process begins with water drawn from both Lake Ray Roberts and Lake Lewisville. The water then goes through a coagulation and flocculation process, where the chemical compound ferric sulfate is used to clump up the “sludge” found in the water. The water then enters the second stage of the process, called sedimentation, where the sludge is given time to settle to the bottom nd given a minimal dose of chlorine with ammonia at the Lake Lewisville plant and Ozone at the Lake Ray Roberts plant.
The Lake Lewisville Treatment Plant will soon join the Lake Ray Roberts Water Treatment Plant in using the safer and more effective cleaning agent, Ozone. With the addition of Ozone, the two water treatment plants will give all Denton residents the same great-tasting water. Another stage of the process, called filtration, uses anthracite, sand, and gravel to rid the water of any leftover sediment and then gives it a final minimal dose of chlorine.
The city of Denton uses an estimated 18.5 million gallons a day (MGD), and both plants combined have a max output of about 50 MGD. The Lake Ray Roberts Plant, which is set to expand its 20 MGD capacity to 100 million MGD.
Denton is among a growing list of cities that are finding ozone treatment of their drinking water makes it safer and taste better, a winning combination all around.
Pesticides have been detected upstream of a reservoir that feeds Melbourne’s drinking water supply. On eight occasions in 2010-11, the levels of pesticides, including simazine, atrazine and DEET, at Sugarloaf reservoir, north-east of Melbourne, were recorded above safe European Union drinking water standards, according to Melbourne Water data obtained by Friends of the Earth through freedom of information. The pesticide levels were within Australian safety limits.
Friends of the Earth believes that this highlights problems with the Winneke treatment plant at Sugarloaf, which was not deigned treat for pesticides. They argue that as a precautionary principle the treatment process at Winneke should be upgraded to deal with these pesticides. Elsewhere in Australia, activated carbon has been used.
Australia limits are set at 20 parts per billion, compared with 0.1 parts per billion in Europe.
Advanced treatment technologies such as ozone, activated carbon, or reverse osmosis can be used remove the pesticides. Ozone has been shown to be particularly effective not just against pesticides but also other micro pollutants found in water. Besides removing these compounds ozone is a good primary disinfectant. This means it can do two jobs at once, remove organic compounds and harmful micro organisms. Unlike chlorine, it does not produce harmful disinfection by products such as chlorinated organic compounds in water such as trihalomethanes or haloacetic acids, both tightly controlled by many water regulatory agencies around the world.
The Los Angeles Metropolitan Board of Directors has authorized construction of $140.4 million of new ozone facilities at the district’s oldest treatment plant. The new facilities will use ozone to replace chlorine as the primary disinfectant at Metropolitan’s F.E. Weymouth Water Treatment Plant in La Verne.
20 years ago, Los Angeles identified ozone disinfection as a more effective treatment process. The board has a plan to convert all five Metropolitan treatment plants to ozone technology because it is the most beneficial and cost-effective way to improve and protect the quality of drinking water served to 19 million Southern Californians.
The Weymouth plant is among the largest water filtration facilities in the nation. The plant treats a blend of waters from the district’s Colorado River Aqueduct and the State Water Project for the central area of Metropolitan’s distribution system in Los Angeles and Orange counties.
Metropolitan will construct the initial phase of facilities at Weymouth, with a capacity to treat 260 million gallons a day with ozone, and up to 345 million gallons per day under certain conditions. The phasing of the ozone processes will allow the district to expand the plant’s ozone treatment capabilities in the future.
Metropolitan initiated the changeover to ozone treatment in 1994 to comply with anticipated federal regulations and to offer a greater margin of safety in its imported supplies. A colorless gas, ozone has been used as a water disinfectant in Europe and parts of the United States for more than a century.
The Metropolitan Water District of Southern California is a cooperative of 26 cities and water agencies serving nearly 19 million people in six counties. The district imports water from the Colorado River and Northern California to supplement local supplies, and helps its members to develop increased water conservation, recycling, storage and other resource-management programs.
A new fashion season results in a flood of new fabrics in a variety of colors. With the beauty comes the reality that producing these textiles comes at a cost to the environment as heavy polluting dyes find their way into the textile industry’s wastewater.
Anew water clean-up technology, developed as part of an EU-funded project, could help the fashion industry clean up its act. The new Sequencing Batch Biofiltration Granular Reactor (SBBGR) helps remove the most polluting textile dyes components – so-called recalcitrant organic compounds – by breaking them down using ozone treatment before applying an innovative wastewater bio-filtering technique.
Benefits of the SBBGR are that it integrates biological treatment with a chemical oxidation treatment, based on ozone, while physically separating these two steps.
Unlike traditional biological systems, this novel biological treatment filter relies on microorganisms growing in aggregates and is separated from the basin containing ozone and the waste. The wastewater is poured over the microorganisms, which process pollutants, and each aggregate holds up to 10 times more microorganisms than conventional technologies.
This new system produces 80% less sludge than traditional biological ones. Sludge is reduced because microorganisms only just survive in these conditions without being able to reproduce. However, there are some negative aspects to the new technology which need to be investigated further; it is expensive to run and consumes a lot of electricity. One of its main positive attributes when faced with competing available wastewater treatment technologies is its ability to be scaled up.
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.