Tokyo Treats Drinking Water with Ozone Biofiltration to Ultra High Quality

Not surprisingly, Tokyo has high quality water available from every faucet in the city. Japan is known for cleanliness and technology, and they combine these passions to treat their drinking water in their capital city.

There are many people who don’t like drinking from the tap and are instead willing to pay for bottles of water. The reality is that many drinking water plants produce water that is equal to or superior to bottled water. This is the case in Tokyo.

The basic quality of Tokyo drinking water is protected by 51 strict quality standards set by the Ministry of Health, Labor, and Welfare, including checks for toxicity and harmful contaminants, along with tests to ensure a palatable tint, clarity, and smell. Japan’s regulations for public water supplies are more stringent than those governing bottled spring water. What takes Tokyo’s water a step higher, though, is the metropolitan waterworks’ strict treatment regimen that includes roughly 200 parameters for safety and quality.

Five treatment plants run by the Tokyo Waterworks supply the city. The Misono plant is one of the five and has a daily treatment capacity of 300,000 cubic meters (about 80 MGD) and utilizes conventional treatment along ozone and biological activated carbon. This additional step removes virtually all remaining contaminants from the water.

Ozone is a strong oxidizing agent that reacts with various contaminants, including carcinogenic compounds, along with microorganisms such as bacteria and protozoa, eliminating potential health risks and improving the taste and odor.

In the second step of the process, water flows from the ozone contact chamber to the bio filtration ponds containing different grades of biological activated carbon. In addition to filtering out organic contaminants, much like a home water purifier, the microporous carbon also supports microorganisms that break down impurities and other byproducts of ozone treatment. If left behind, these contaminants can degrade the taste and smell of water.

The quality of source water determines the level of water treatment. Tokyo currently gets 80% of its water from the Tonegawa and Arakawa Rivers, drawing the remaining 20% from the Tamagawa River. The Tamagawa is pure enough that it only needs standard treatment to make it drinkable. Tonegawa and Arakawa Rivers require the advanced treatment explained above.

In the US and Canada many large drinking water plants have adopted the ozone biofiltration treatment process. In fact, in the US over 1.6 billion gallons of water a day are treated with ozone. Many of these plants have held contests where customer try to determine which is better in a blind taste test, tap water or bottled water. In many of the cities using advanced ozone water treatment, tap water wins.

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North Texas Municipal Water District Begins Operating Nations Largest Ozone Drinking Water Facility

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.

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Valdosta Water Plant with Ozone Primary Disinfection wins State Award

The City of Valdosta Water Treatment Plant has been recognized as the 2013 Water Treatment Plant of the Year by the Georgia Association of Water Professionals (GAWP).

The plant was recently evaluated by GAWP inspectors on its well field operations, chemical processes and documentation, and scored 90% or better in all areas.

The water treatment plant processes over 3.5 billion gallons of drinking water for its residential, business and industrial customers annually. The state-of-the-art facility obtains the city’s water supply from 7 wells that are drilled into an underground layer of porous, water-bearing limestone known as the Upper Floridan Aquifer.

Originally built in 1992, the plant’s major treatment systems were upgraded in 2007 to maintain quality water services while keeping up with city growth. The plant uses ozone as the primary treatment process and was the first municipal plant in Georgia to use this technology. It has many innovative features, including on-site generation of sodium hypochlorite for secondary disinfection and computer monitoring and control of treatment processes.

The Georgia Association of Water Professionals (GAWP) is a not-for-profit association founded in 1932 with membership of over 4,000 water and wastewater treatment professionals. The organization’s main purpose is to educate and assist those who have an interest in the proper management and protection of Georgia’s water resources.

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