Seventh Grader Demonstrates the Danger of Ozone for Home Air Purification

In a previous post, we noted that the EPA found that air purifiers that emit ozone either did not work or if they did emitted dangerous levels of ozone in the air. This area was not very well regulated, but recently California has taken steps to regulate ozone generators for home use.

Seventh grader Otana Jakpor was also concerned about this type of ozone generators after reading an article in Consumer Reports. The article indicated the potential dangers of these devices. While most seventh graders would have left it at that, Otana designed experiments to confirm the issues brought up in the Consumer Reports article.

Her work spanned a period of two years. Some purifiers, she found, emitted ozone levels equal to Stage 3 smog alerts. She provided her findings to the California Air Resources Board at the board’s invitation. Her testimony contributed to the regulations that were put into place to regulate ozone generators for home use.

Otana went on to be awarded the President’s Environmental Youth Award and the Action For Nature’s 2009 International Young Eco-Hero Award in the ages 8 to 16 category. She has met with senators and the head of the U.S. Environmental Protection Agency. She is now a volunteer spokesperson for the American Lung Association and will have her study published in the journal of the American Thoracic Society.

Besides the significant personal accomplishment, Otana research confirms work done by others and provides a warning to homeowners in states that do not regulate ozone generators for home use that they need to be very careful in the purchase decisions and use of these devices.

Spartan Environmental Technologies does not sell ozone generators for residential use.

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Spartan Environmental Announces High Output – High Efficiency Ozone Generators

Spartan Environmental Technologies and Ozono Elettronica Internazionale (Milan) announce two new lines of ozone generators, the TPF XT and MCP XT. These new ozone generators offer both high output and energy efficiency.

The TPF XT can produce ozone from either air or oxygen. Configured for air feed, TPF XT series can produce ozone at 2-3 weight percent from 42 to 480 lbs/day. Using oxygen feed, ozone can be produced at 6-10 weight percent from 69-913 lbs/day. Power consumption is 9.5 kWh/kg of ozone produced. These systems, designed primarily for water treatment applications, can treat up to 50 million gallons per day of water for applications such as drinking water treatment.

The smaller MCP XT series can also produce ozone from air or oxygen. Configured for air feed, the MCP XT series can produce ozone at 2-3 weight percent from 2 to 37 lbs/day. Using oxygen feed, ozone can be produced at 6-10 weight percent from 4-69 lbs/day.

Both series employ IGBT electronics with PLC based controls. Components in contact with ozone are made of 316 L stainless or flouropolymers. The electrical components conform to CE, with UL rating available upon request. Air fed systems come with on board air dryers capable of achieving -70 degree C dew point feed gas.

Anthony Sacco, Marketing Director for Spartan, said: “Spartan is pleased to offer these high performance systems to our customers in the United States and Canada. With increasing interest in alternative water treatment technologies, these high efficiency ozone generators should offer water treatment companies additional options for water purification.”

Spartan Environmental Technologies is a supplier of ozone generators and integrated ozone and advanced oxidation systems for industrial and municipal water and wastewater treatment applications.

Ozono Elettronica Internazionale is a Milan (Italy) based manufacturer of ozone generators with over 35 years of experience in supply ozone generators and related equipment to the water treatment industry around the world.

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Technical & Educational Council of the AWWA

We have been asked by the American Water Works Association (AWWA) to distribute the following information on the Technical & Educational Council (TEC). As a member of the AWWA and the disinfection committee of the TEC, we are pleased to share information on the TEC mission.

The TEC is responsible for many AWWA activities involving the design, construction, operation, and management of water utilities; water quality research and science; and providing training opportunities to our membership.

TEC includes over 1,100 active volunteer members comprising eight divisions:
• Distribution &
• Plant Operations
• Engineering
• & Construction
• Management
• Small Systems
• Water Conservation
• Water Science
• & Research
• Water Resources
• Water Quality

TEC provides leadership to AWWA through:
• Technical direction for AWWA Conference organization and technical program development
• AWWA Manuals of Practice
• AWWA Policy Statements
• Technical White Papers
• Member Recognition
• Management Forums
• E-learning Opportunities

Conferences and Symposium Sponsored by TEC include:
• AWWA Annual Conference & Exposition technical program
• Distribution Systems Symposium & Exposition
• Customer Service Conference & Exposition
• Information Management & Technology Conference & Exposition
• Water Quality Technology Conference® & Exposition (WQTC)
• Water Security Congress
• Utility Management Conference
• Membrane Technology Conference & Exposition
• Sustainable Water Sources Conference & Exposition
• Inorganics Workshop Research Symposium
• Water Conservation Workshop
• Water Resources Symposium
• International Symposium on Waterbourne Pathogens
• WateReuse Symposium
• Leading Edge Conf. on Strategic Asset Management

If you are a member of the AWWA, you have benefited by the activities of the TEC. If you are not a member, you may want to consider joining. Please visit www.awwa.org.

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Protecting Ozone Generators – Gas Preparation

In the last couple of posts we have been talking about protecting ozone generators from damage. Today we will cover preparing the feed gas for the generator. The most important parameter in gas preparation, whether it is an air fed or oxygen fed system, is moisture control. Virtually all ozone generator manufacturers insist on dry gas being fed to their units. Typical dew points are -100 degrees F.

For air fed systems, refrigeration units on the compressors and desiccant dryers were used in the past. More recently pressure swing absorption (PSA) systems have been adopted. the latter have fewer moving parts and are easier to maintain. They do require higher pressure compressed air, in range of 100 psi to work efficiently. In any event, the goal is to remove the water to the -100 degree F dew point level.

For oxygen systems, PSA systems can also be used. In this case, oxygen is concentrated from air to 90-93% in the system. Water is also captured in this process, so dry oxygen gas is prepared. Alternatively, liquid oxygen can be evaporated as the feed gas. This material is inherently dry.

To insure effective drying, moisture sensors should be employed, especially in larger system. These monitors can directly provide the dew point value. Alarms can alert operators, or computer systems, to take action before moisture levels reach values that can result in damage to the equipment. For smaller system, silica gel moisture indicators are a low cost option to follow moisture changes as a change in color of the gel.

PSA systems can be a source of particulate contamination in the gas stream due to the attrition of the molecular sieves used to absorb nitrogen or water. So the use of particulate filters is important. these filters should be in the range of 0.5 to 1.0 micron in size.

For PSA systems, oxygen sensors can provide the oxygen concentration in the gas feed. an alternative is to follow the pressure of the concentrator since a drop of pressure below the recommended level is also an indication the the output concentration has been compromised.

Both ozone generators and PSA systems can be adversely affected by oil and other hydrocarbons. This can be a severe problem with oil lubricated compressors, but hydrocarbons from the environment can also pass through oil free compressors. In the case of oil lubricated compressors, coalescing filters must be used. It is also recommended to use activated carbon filters to polish the gas stream to remove any remaining hydrocarbon. Such filters cna lower hydrocarbon levels to less than 3 ppm.

The cost of a good gas preparation system is well below the potential damage cost by contaminated gas reaching the generator or explain why the generator is not producing ozone at the design vale.

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Protecting Ozone Generators – Back Flow Prevention

In our last post, we discussed ozone generator protection in general. In this post we will cover protecting the ozone generator from back flow of water. When ozone is being injected into a pressurized water line, it is possible under certain conditions for the water to back flow into the generator causing sever damage to the system.

In order to prevent this catastrophic failure, back flow prevention systems must be used. Given the potential damage possible, multiple protection devices are employed. The simplest is a check valve. While check valves are simple and inexpensive, they are not particularly reliable. Check valves are almost always used, but not as the sole method of protection. A new type of check valve using the hydrophobic properties of flouropolymers are being tested as a solid state check valve, but these devices have seen limited use to date.

Typically, ozone is introduced into pressurized lines by means of a venturi injector. The venturi creates a vacuum that draws the ozone gas into the liquid. If this vacuum is lost, it is possible that water could back flow. So, one protection method employed is a vacuum switch. When vacuum is lost a signal can be sent to a solenoid valve to close before water has a chance to flow towards the ozone generator. Alternatively, a pressure switch could be used if it is set below the pressure of the generator.

A third level of protection employed is a liquid trap. This device has a float that opens when water back flows into it. The float opens a line to drain to divert the back flowing water to the drain instead of the ozone generator. It is important to make sure that the materials in the liquid trap are compatible with ozone exposure.

A fourth level of protection is a sensor that detects liquid somewhere in the gas line between the venturi and the ozone generator. One such device employs ultra sonics. It has a forked sensor that can detect a difference between air and a liquid in the gap of the fork. This signal can be used to shut the solenoid valve protecting the ozone generator.

A well designed ozone water treatment system with ozone feed into a pressurized line should have at least two and probably three of these devices in place to protect the ozone generator. Spartan Environmental Technologies employs a three way protection system in its SPARTOX ozone water treatment system.

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Protecting Ozone Generators

We often hear potential ozone users worry about the reliability of ozone generators for ozone water treatment applications. The reality is that well made ozone generators can last 10-20 years with good preventative maintenance programs. The fact that many systems don’t last this long is a result of either poor gas preparation or back flow of water into the generator.

In terms of gas preparation, the main issues are moisture, hydrocarbons and particulates. Moisture lowers efficiency and can cause corrosion due to the formation of nitric acid in the generator. A good system for drying the gas is critical. For larger systems, it is wise to invest in dew point monitors to measure the level of moisture in the gas. Particulates and hydrocarbons can deposit on the electrodes in the generator impacting efficiency. They can also lead to heating of the electrodes with potential damage to the dielectrics.

If water enters the ozone generator catastrophic damage will be done to the system. So, it is critical that water be prevented from entering the unit during operation or during periods when the unit is not active.

In coming posts we will cover each of these factors impacting reliability in detail.

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United Water Upgrades Ozone Equipment

United Water completed a $100 million rehabilitation of the Haworth Water Treatment Plant including ozonation equipment. The improvements were the largest single capital investment for United Water during its 140-years of operation.

The project was driven by drinking water regulatory compliance issues. These were caused by pollution of the source water. Better protection of the reservoir would have probably resulted in a less costly solution, but the process improvements at the plant will bring the drinking water into compliance.

The upgrade included a new ozone system, which will reduce the energy needed to disinfect and remove unwanted tastes and odors from the water. Ozone is widely used in situations where both disinfection and taste/odor problems are present. The facility previously used ozone, so the investment shows that this method of water treatment worked well.

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