Algae Control Using Ultrasound

Normally, this blog focuses on ozone and advanced oxidation technologies for water and air treatment. An interesting non chemical water treatment for algae control might be of interest to the readership of the blog.

Algae blooms can create both aesthetic and other problems for tanks, ponds and lakes. Chemical treatments are routinely used, but require adding toxic chemicals to the water and in safe doses might not always be effective. An alternative is the use of ultrasound.

The complex pattern of ultrasonic vibrations through the water causes the algae vacuole cell wall to resonate and break, much like a glass breaking from a high pitched sound. The broken vacuole wall eliminates algae’s ability to grow and reproduce, while the same vibrations are harmless to humans, animals, fish and other aquatic plants. The discovery that ultrasound waves in water kill algae was made over sixty years ago in submarine sonar experiments. the Navy discovered that surfaces impacted by the sonar waves did not accumulate algae as other areas not covered by algae did. This eventually led to the study of the phenomenon for algae control.

It is important to note that ultra sound alone might not be enough to solve all of the problems associated with a pond or lake. Even if the algae is killed, the pond might not contain enough bacteria or oxygen to break down the organic matter found in the water, including the algae killed by the ultra sound system. So, proper control of algae requires a balanced ecosystem which has sufficient oxygen and proper bacteria present in conjunction with the ultrasound.

Another issue is that some algae do not have the same physical structure as other algae and thus are not affected by ultrasound. Prior to applying ultrasound, the algae in a given body of water should be tested to make sure that it does not contain these algae species.

Although the method has some limitations, ultrasound algae control offers an economical treatment option for small bodies of water that has been used in a wide range of ponds, lakes and water treatment facilities.

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Ontario Studies Advanced Oxidation for Wastewater Treatment

Ontario is investing in innovative solutions to help protect Great Lakes water quality. The Keswick Water Pollution Control Plant is testing an advanced oxidation process to reduce the amount of phosphorus and micro pollutants such as pharmaceuticals and personal care products entering Lake Simcoe.

Advanced oxidation processes have been demonstrated to remove pharmaceutical and personal care products from water and wastewater and several municipalities have initiated treatment systems based on this technology already.
The Keswick project is part of Showcasing Water Innovation, a program that supports projects that demonstrate innovative and cost effective approaches to improve drinking water, wastewater treatment, and storm water systems that can be used by communities across the province.

The program is helping communities find innovative wastewater treatment solutions to keep Great Lakes healthy. 80 percent of Ontarians get their drinking water from the Great Lakes. Water and wastewater is the largest sub-sector of Ontario’s environment industry employing 22,000 people and generating and $1.8 billion in sales.

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Poughkeepsie Looks to Ozone To Treat Drinking Water

New federal drinking water standards could require the Poughkeepsie water plant to make $16 million in upgrades. The U.S. Environmental Protection Agency is requiring municipal water plants to do more to restrict disinfectant byproducts (DBP) in drinking water that could pose health hazards.

Poughkeepsies’ Water Treatment Facility is looking at injecting ozone into the drinking water for treatment. Ozone is used by other municipalities for control of disinfection byproducts. Chlorine in the water reacts with organics to form the DBP, which are potential carcinogens. Using ozone as the primary disinfectant signifincatly reduces the amount of chlorine used and thus reduces the formation of the DBP.

Other methods would cost more. The plant which provides water for the town and city of Poughkeepsie is seeking help in making the project as affordable as possible. Federal and state assistance with borrowing the money would help. Expanding the customer base of the plant, including interesting a major company or two to locate in Poughkeepsie, would also help in making the upgrade more affordable. The plant treats 9 million gallons of Hudson River a day, but has a capacity to treat 19.3 million.

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Singapore’s River Safari Uses Ozone Water Treatment

Singapore operates a number of parks under its Wildlife Reserve brand. These include the Singapore Zoo, Night Safari, and the Jurong Bird Park. The newest park is River Safari, the first river themed park in Asia. It will include eight major rivers from around the world including the Mississippi, Congo, Nile, Ganges, Murray, Mekong, Yangtze and Amazon rivers. The exhibit allows visitors to learn more about the various freshwater habitats supported by these river systems.

Such an exhibit requires a sophisticated aquatic life support system to maintain over 1 MM gallons of water. Each exhibit within the park will have its own treatment system to prevent cross contamination between species, keep the animals healthy and make the experience safe and pleasant for the visitors.

The extensive water treatment system will include course screens, drum filters, high rate sand filters, ozone, UV, chlorination, bio filtration and aeration. All of these treatment methods are coordinated to control turbidity, color, bacteria, nitrate, phosphates, dissolved oxygen, pH and other important water quality factors.

The water treatment system recycles water used in the park as part of the facilities overall conservation efforts. The main use for make up water will be for filter back wash and will come from the existing potable water system in Singapore.

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Upcoming Ozone Related Meetings and Conferences 2012

The following ozone related conferences are being held this year:

September 1-2 Mexican Ozone Congress in Mexico City, Mexico (www.rubiopharma.com/seminarios.asp)
Spetember 16-21 IWA World Water Congress and Exhibition in Busan, Korea (www.iwa2012busan.org)
September 24-26 International Ozone Association Meeting in Milwaukee, WI USA (www.io3a.org)
September 29-October 3 WEFTEC2012 in New Orleans, LA USA (www.weftec.org)
October 22-23 Japan Ozone Association Seminar on Ozone Technology in Tokyo, Japan (www.j-ozone.org)
November 4-8 2012 Water Quality Technical Conference in Toronto, ON Canada (www.awwa.org)
November 21-22 IWRM Karlsruhe 2012 in Karlsruhe, Germany (www.messe-karlsruhe.de)

Spartan will be attending and blogging from the international ozone association meeting in Milwaukee, WI.

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Ozone for Disinfection By Products Control in Drinking Water

Disinfection of drinking water often involves a trade off between inactivating pathogens and creating undesirable disinfection by products in water. Because chlorination is still the most widely used method of disinfection, problems with the formation of chlorinated byproducts due to the interaction of chlorine with organic compounds found in water is a major issue. Two basic classes of compounds are formed: trihalomethanes and haloacetic acids. Both are tightly regulated by the EPA to values under 80 ppb since they are considered suspected carcinogens.

One of the reasons ozone is used as a primary disinfectant in drinking water is that it does not form these compounds. Ozone water treatment can be used as a method of disinfection byproduct control. Chlorine is often used as a secondary disinfectant with ozone to protect the distribution system. In this arrangement, the use of ozone reduces the amount of chlorine required. So, less chlorine results in fewer chlorinated byproducts while maintaining the positive benefits of chlorine.

Ozone is not without the potential to form disinfection byproducts. The most notable is bromate which can be formed if bromide ion is present in the drinking water. Approximately 25% of drinking water sources contain bromide ion, so ozone may not always be indicated for disinfection. In cases where bromide is present, it is still possible to use it by modifying the treatment conditions, a simple method is to limit the amount of ozone used or to adjust the pH to a lower value where possible. More sophisticated methods are also available where the benefits of ozonation are important.

Virtually all disinfection methods have the potential to form disinfection byproducts, but by combining methods and anticipating potential problems, these issues can be minimized.

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Olympics Threaten By Ozone

Normally, in this blog we focus on the application of ozone in the treatment of water. Given that the Olympics are taking place in London the following news item caught our eye.

During the week leading up to the Olympic Games, London experienced its worst ozone episode for six years. Fortunately fresh westerly winds began to clear London’s air pollution just before the opening ceremony.

On 21 July high pressure moved over the UK and air began to slowly circulate over southern England and the near continent, one of the most densely populated and industrial areas of Europe. Ground-level ozone slowly built up due to the action of sunlight and high temperatures on pollution emitted from vehicles and industry.

Ground level ozone peaked in London on 25 July reaching high levels according to the UK air quality index: they exceeded the World Health Organisation Guidelines by around 80% and resulted in an emergency pollution alert. Ozone concentrations remained above WHO guidelines for most of the following night.

So, it might be interesting to know what type of ozone the people in London were worried about.

In the Earth’s lower atmosphere, near ground level, ozone is formed when pollutants emitted by cars, power plants,chemical plants, and other sources react chemically in the presence of sunlight. Ozone pollution is a concern during the summer months when the weather conditions needed to form ground-level ozone; lots of sun, hot temperatures normally occur.

Ozone can irritate your respiratory system, causing you to start coughing, feel an irritation in your throat and/or experience an uncomfortable sensation in your chest. Ozone can reduce lung function and make it more difficult for you to breathe as deeply and vigorously as you normally would. When this happens, you may notice that breathing starts to feel uncomfortable. If you are exercising or working outdoors, you may notice that you are taking more rapid and shallow breaths than normal. Ozone can aggravate asthma. When ozone levels are high, more people with asthma have attacks that require a doctors attention or the use of additional medication. One reason this happens is that ozone makes people more sensitive to allergens, which are the most common triggers for asthma attacks. Also, asthmatics are more severely affected by the reduced lung function and irritation that ozone causes in the respiratory system. Ozone can inflame and damage cells that line your lungs. Within a few days, the damaged cells are replaced and the old cells are shed much in the way your skin peels after a sunburn. Ozone may aggravate chronic lung diseases such as emphysema and bronchitis and reduce the immune systems ability to fight off bacterial infections in the respiratory system.

So, thankfully, the athletes of the 30th Olympiad did not have to face high levels of ozone and can be faster, higher and stronger.

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