Technology

Ozone Facts

Why use Ozone (O3)?

Ozone’s benefits are numerous. The following are some examples of these benefits:

  • The strongest single oxidizing agent available – 152% stronger than chlorine over a broad pH range
  • On-site generation – no transportation, handling or storage of hazardous compounds
  • Environmentally compatible operation
  • No added taste or odor
  • No irritation to skin, ears and nose when dissolved in water
  • Simplified water chemistry by reverting to oxygen
  • The pH neutral chemical makeup does not affect the pH balance of water like traditional chemicals
  • Reduction of chlorine or bromine consumption to a minimum, saving money on maintenance and material handling
  • No THM (Trihalomethane) formation
  • Bacteria free water
  • Potential extension of food products’ life
  • Improved product quality
  • Possible prevention in the need for Risk Management Plans
  • Possible prevention in the need to report for Title III

For more information about the benefits of ozone in regards to a specific application, check out the information in each business unit listed under Products/Services.

Application Experience with Ozone (O3)

Piper Environmental Group, Inc. designs and builds integrated ozone systems for a multitude of different industries and processes. An example of our industry and application expertise follows:

  • Aquaculture
  • Barrel Washing (Wineries)
  • Clean-in-place (Food processing & Wineries)
  • Color Removal
  • Cooling Towers
  • De-ionized Water
  • Etchant Rejuvenation
  • Flume Treatment (Food)
  • Fume Scrubbers
  • Hydroponics
  • Groundwater Remediation
  • Industrial Processes
  • Mammal Water Disinfection
  • Microbiological Control
  • Odor Control
  • Phenol Reduction
  • Process Waters
  • Recreational Water
  • Sanitation
  • Soil Remediation
  • Spray Washing (Food)
  • Taste Control

What is Ozone (O3)?
Background
Ozone is triatomic oxygen. It is distinguishable by a characteristic odor, first reported by Dutch chemist Martinus Van Marum in 1785, in the vicinity of an electrical discharge. In 1840, Christian Shonbein identified this characteristic odor as a previously unidentified compound. He named it ozone after the Greek word ozein, meaning “to smell.” The identity and structure of this compound was confirmed in 1867 as triatomic oxygen.

Chemical Properties
The three atoms of oxygen that make up one molecule of ozone are nearly the shape of an equilateral triangle. The electrical bonding between each oxygen molecule is achieved by sharing six electrons, two of which resonate between all three atoms. It is these electrons, which participate in the electrophillic attack on many substances during the oxidation process.

Ozone is the most powerful known oxidizing agent that can be used on a practical scale for treatment applications. For example, the comparative oxidizing strengths of ozone, chlorine, and chlorine dioxide are 2.07, 1.36, and 1.275 volts versus hydrogen, respectively.

Ozone is fairly stable in cool, dry air and has a half-life of several hours to several days at low concentration based on a variety of factors such as temperature, pressure and pH.   In water, however, ozone’s half-life is instantaneous to several hours in soil, due to low temperature.   Because ozone is very reactive, ozone can oxidize material between 10 to 1000 times faster than most oxidants used.   In some instances of organic oxidation, the material can be completely oxidized to carbon dioxide and water.

Pure ozone is approximately 12.5 times more soluble in water than oxygen.  Ozone treatment systems traditionally inject air containing 1-6% ozone concentrations by weight into water.  At these levels the maximum solubility of ozone is between 2 and 6 ppm, respectively, depending primarily on temperature and pressure.

Ozone Production
Because ozone has such a short half-life, it cannot be stored.  Instead, it must be generated on site and used immediately.  Electrical generation utilizes the most practical and safe method for large scale applications of ozone.  The most widely used electrical generation technology is the corona discharge method.  A corona discharge generator accelerates electrons, providing sufficient energy to split the oxygen-oxygen double bond upon impact with another oxygen molecule.  The two oxygen atoms produced by the collision react with other diatomic oxygen molecules to form ozone.

When enough high energy electrons bombard gas molecules so they are ionized, a light emitting gaseous plasma is formed.  This is commonly referred to as a corona.  In practice, corona discharge generators can produce ozone concentrations of 1-2% using air and 3-12% using oxygen.

Properly designed corona discharge generators utilize higher frequencies (typically 300-1000 Hz) are favored because greater ozone production can be achieved with less electrode surface area and less electrical consumption.

The corona discharge device can be fabricated and configured in many different ways. The basic purpose is to maximize ozone production and concentration by generating a corona between two electrode surfaces. Corona discharge units properly designed and containing modern safety features can produce ozone reliably, efficiently, and safely for many years.

 

Ozone – Environmental Health & Safety

 

Toxicology

Ozone is a toxic gas.

Ozone gas has a distinct odor – described as sweet and pungent or as “melon rind” by winemakers, which is detectable at low levels. People in the vicinity will be aware if a leak is present. Piper Environmental Group believes strongly in utilizing ambient ozone monitors interlocked with ozone generators to shut down ozone production in case of a leak.

The human detection level of ozone is approximately 0.03 to 0.07 ppm, depending upon the individual’s sensitivity and health. Therefore, personnel will generally smell ozone long before it becomes a concern to health.

Ozone is neither carcinogenic nor persistent.

OSHA has specific limits for worker exposure. For more details, please refer to OSHA link following this section. The OSHA PEL-TWA is 0.1 ppm for an 8 hour period. “PEL” indicates “Personal Exposure Limits” and “TWA” refers to “Time Weighted Average” for an 8-hour period with two 10-minute breaks and 30 minutes for lunch.

The OSHA PEL-STEL is 0.3 ppm for 15 minutes.  “STEL” is short term exposure limit. NIOSH (National Institute for Occupational Safety and Health) has taken a position that less exposure is acceptable.  If a worker has been exposed to ozone, specific symptoms will occur.  In the event of acute exposure, the following symptoms have been reported:

  • Dryness of mucous membranes, specifically the nose and throat
  • Headache
  • Eye irritation
  • Nausea
  • Vomiting
  • Difficulty breathing

In severe or chronic exposure, pulmonary edema will result. Even after pulmonary edema, the lungs will clear within a month. There have been no reports of death associated with ozone. Researchers estimate exposure to ozone at 50 ppm for 60 minutes can be fatal to humans.

Safety

Safety is a primary concern for Piper Environmental Group’s employees and customers. Ensuring proper design and application of the ozone systems will greatly increase worker safety. Most problems we have seen are a result of incompatible materials, inadequate mixing and degassing, and a lack of destruct systems.

We design our systems to be as safe as possible with ambient ozone monitors to shut down the ozone generator at multiple points. In addition, our systems utilize remote off and external shut down systems.

Personnel can also utilize hand held ozone monitors to ensure that any leaks are identified and fixed in a timely manner. Ambient ozone monitors that shut down the ozone generators in case of a leak are the most reliable means to ensure personnel safety.

Safety & Environmental Links
OSHA homepage
www.osha.gov

Ozone in the workplace, OSHA standards
www.osha.gov/dts/sltc/methods/inorganic/id214/id214.html

State of California site for ozone
http://www.arb.ca.gov/research/aaqs/caaqs/ozone/ozone.htm

Federal site for ozone and other air pollutants
www.epa.gov/airnow