Ozonation of drinking waters containing algae sometimes has a beneficial effect on the process of coagulation. It is hypothesized that the extracellular organic matter (EOM) from the algae affects the flocculation process. The effects on algal particle stability and flocculation due to ozonation and the role of EOM were investigated. Four species of algae were cultivated and EOM from the algae extracted. Scanning electron micrographs (SEMs) of the algae indicated little cell lysing for ozone doses of 3 mg/L or less. Extensive cell wall alteration was observed. Lysis of algae cells was prominent at 8 mg/L ozone. Ozonation decreased the algae volume concentrations and cell sizes. Cyclotella and Scenedesmus produced ten times as much EOM per unit cell number than Chlorella. The EOM of Cyclotella and Scenedesmus was also of higher molecular size than that of Chlorella. Increasing the ozone dose to extracted EOM and alginic acid, a model EOM compound, resulted in decreasing molecular size, colloid charge and increasing hydrophilicity and functional group charge. Bench scale jar tests and flocculation kinetic experiments were performed. Ozonation was not effective in decreasing the polymer dose required to coagulate the algae. However, ozonation improved overall removals of Scenedesmus, Cyclotella and Synura. Ozonation also increased the flocculation rate of Scenedesmus and Cyclotella, but had a detrimental effect on the rate for Chlorella. Increasing calcium (up to 30 mg/L as CaCO$\sb3$) and ozone dosage increased the flocculation rate of Scenedesmus. Natural waters spiked with Cyclotella and Synura showed an increased flocculation rate upon ozonation.
About a week ago we posted about how ozone is made. That original post gave the fundamentals of how ozone is produced in nature and the basics of how ozone is produced within ozone generators, both UV ozone generators and corona discharge ozone generators. It was pointed out then that most (almost every) industrial ozone generator uses corona discharge to produce ozone. This 2nd installment is dedicated to informing you the reader about ozone generation from corona discharge.
The fundamentals are simple. A spark (corona discharge) is used to split the diatomic oxygen molecule into valant oxygen atoms. These oxygen atoms have a negative charge and will bond quickly with another oxygen molecule to produce ozone! For each split oxygen molecule 2 ozone molecules are produced.
Ozone Generation from Corona Discharge
A power supply is used to produce an electrical discharge across a dielectric, and an air gap. The dielectric is used to diffuse the discharge across a large area as opposed to single point like a normal spark. The oxygen molecules passing through the air gap are exposed to the electrical discharge and are split into ozone (at least that is the hope). A great deal of heat is generated from this process and is removed from the electrodes as shown.
Corona Discharge Tube
This image shows a more complete picture of a very typical ozone generation corona cell. The dielectric is a tube allowing the air gap to flow around the outside of the dielectric, with the electrode around the outside. This allows heat to be dissipated to the outside of the electrode efficiently.
This video shows a great example of ozone production from corona discharge.
There are three main factors when generating ozone from corona discharge:
Power supply
Operating voltage
Operating frequency
Dielectric
Glass
Ceramic
Mica
Quartz
Corona Cell
Tube – cylindrical style
Flat plate
When generating ozone from corona discharge there are a few factors that will affect performance that must be evaluated.
Cooling of the corona cell
Water cooled
Air cooled
Feed gas
Oxygen
Dry Air
I will try to cover some of these fundamentals and why one may be better than another for your specific application in future installments of “how ozone is made“
Study: Ozone From Rock Fracture Could Serve As Earthquake Early Warning
November 16, 2011 — Researchers the world over are seeking reliable ways to predict earthquakes, focusing on identifying seismic precursors that, if detected early enough, could serve as early warnings.
New research, published this week in the journal Applied Physics Letters, suggests that ozone gas emitted from fracturing rocks could serve as an indicator of impending earthquakes. Ozone is a natural gas, a byproduct of electrical discharges into the air from several sources, such as from lightning, or, according to the new research, from rocks breaking under pressure.
Scientists in the lab of Raúl A. Baragiola, a professor of engineering physics in the University of Virginia School of Engineering and Applied Science, set up experiments to measure ozone produced by crushing or drilling into different igneous and metamorphic rocks, including granite, basalt, gneiss, rhyolite and quartz. Different rocks produced different amounts of ozone, with rhyolite producing the strongest ozone emission.
Some time prior to an earthquake, pressures begin to build in underground faults. These pressures fracture rocks, and presumably, would produce detectable ozone.
To distinguish whether the ozone was coming from the rocks or from reactions in the atmosphere, the researchers conducted experiments in pure oxygen, nitrogen, helium and carbon dioxide. They found that ozone was produced by fracturing rocks only in conditions containing oxygen atoms, such as air, carbon dioxide and pure oxygen molecules, indicating that it came from reactions in the gas. This suggests that rock fractures may be detectable by measuring ozone.
Baragiola began the study by wondering if animals, which seem – at least anecdotally – to be capable of anticipating earthquakes, may be sensitive to changing levels of ozone, and therefore able to react in advance to an earthquake. It occurred to him that if fracturing rocks create ozone, then ozone detectors might be used as warning devices in the same way that animal behavioral changes might be indicators of seismic activity.
He said the research has several implications.
“If future research shows a positive correlation between ground-level ozone near geological faults and earthquakes, an array of interconnected ozone detectors could monitor anomalous patterns when rock fracture induces the release of ozone from underground and surface cracks,” he said.
“Such an array, located away from areas with high levels of ground ozone, could be useful for giving early warning to earthquakes.”
He added that detection of an increase of ground ozone might also be useful in anticipating disasters in tunnel excavation, landslides and underground mines.
Baragiola’s co-authors are U.Va. research scientist Catherine Dukes and visiting student Dawn Hedges.
Why buy new, when used will do? Here at Ozone Solutions we maintain a full line of used ozone equipment on our Ozone Classifieds page. Recently we received a few new items that are in great shape and common sellers.
We had a customer with 2 OZV-8S Ozone Generators and 2 V-20 Air Dryers with only a few months of use that decided to upgrade to different equipment. These pieces are in great shape, look almost like new, and are listed well below list price. Together these components will generate 4 g/hr of ozone from dry air. This is a great combination to be used with an existing ozone injection system, or a new project. These components would work great with an ozone injection system like the OSW-10.
New price for the V-20 Air Dryer is $1295. We are selling these used air dryers at a price of $550 each.
For more used ozone equipment, including used ozone generators, used oxygen concentrators, and used ozone monitors, see our entire classified site HERE.
Ozone Solutions sells the Chemetrics K-7402 Vacuvial kits. These are a great coloremetric kit to verity dissolved ozone levels in water.
The K-7402 test kit comes with everything necessary for 30 tests. After 30 tests a refill kit is necessary. This is part number R-7402.
We just lowered the price from $29.97 to $23.26. This lowers testing cost from $1.00 per test to $0.78 per test. If you are in need of a great reference standard for dissolved ozone, the K-7402 test kit may be the perfect tool for the job.
Ozone Solutions has just today created a new Ozone Monitors website. This is a new website dedicated to ozone monitors where we can showcase featured ozone monitors. Check out this new website by clicking either the link above or the following image!
Did you know that becoming a member of the IOA allows for free access to all the papers published by the Ozone: Science & Engineering Journal? To learn more about becoming a member of the IOA click HERE.
Ozone is produced naturally through sparks and UV-Light, ozone is also produced commercially for many uses. This will outline a few methods ozone is produced.
Ozone is Produced Naturally from Lightening During Thunderstorms.
Ozone is Produced Naturally from UV Light from the Sun
These same methods of ozone generations can be used commercially for industrial ozone applications. Great advancements have been made in the ozone industry to produce ozone more reliably and efficiently.
Ozone Production from Corona Discharge
Oxygen flowing between an electrode and cathode produces ozone from a spark, more commonly referred to as Corona Discharge.
Ozone Production from UV Light
Ozone can be produced from a UV light tuned to the proper wavelength inside an enclosed chamber.
Ozone can also be produced directly in water using an electrolytic cell. This method uses a current within the water to split the oxygen and hydrogen atoms, then converts the oxygen directly into ozone. This is a fairly new commercial ozone generation method that may show great promise in the future. At this time, this application has very limited application.
Commercial Ozone Generation
Corona Discharge (electrical discharge field)
High voltage spark at medium to high frequencies
Creates ozone at medium – high concentrations (up to 22%)
Most commonly used
UV Ozone Generation (photochemical)
Low concentration ( max 2% concentration)
Small ozone outputs
Electrolytic
Currently only small outputs
Ultra pure water is necessary
The most common method of ozone generation is corona discharge. Due to the low operation costs, and improved reliability this will be the main method of ozone generation for many years to come, for more information on ozone generation watch for future installments of “How Ozone is Made“
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