Chlorine Dioxide

GUARDIAN CSC has worked with chlorine dioxide and its various generation methods for over 20 years. Guardian CSC offers engineered, installed, and continuously monitored systems for many use applications. Some of the more common applications as well as benefits are listed below.

Of the oxidizing biocides, chlorine dioxide is the most selective oxidant. Both ozone and chlorine are much more reactive than chlorine dioxide, and they will be consumed by most organic compounds. Chlorine dioxide, however, is more selective and is not wasted on peripheral compounds, allowing it to go directly to the application. This allows much lower dosages of chlorine dioxide to achieve a more stable residual than either chlorine or ozone. Chlorine dioxide can be effectively used in much higher organic loading than either ozone or chlorine because of its selectivity.

  • Effective Biocide At Low Concentrations
  • Removes Biofilm
  • No THM Or HAA’s Formation
  • No Chlorophenols
  • Effective Legionella And Other Bacterial Control
  • Not pH Dependent, 2-10
  • Environmentally Friendly, Green Technology
  • Low CT Values
  • Approved By EPA For Potable Water, < 0.80 PPM Max
  • CFR Approved For F&B
  • 5-10 PPM Sanitizing Without Potable Rinse Per The Brewery Industry

LEGIONELLA PREVENTION AND CONTROL

In the prevention and control of Legionnaire’s Disease-causing microbes, chlorine dioxide has taken an eminent role. The specific characteristics of the disinfectant make sure ClO2 gets the job done where others fail.

Biofilm in the piping can protect Legionella from most of the disinfectants.

Chlorine dioxide, however, removes the biofilm and kills the bacteria, spores, and viruses.

Other advantages are:

  1. The bactericidal efficiency is relatively unaffected by pH values between 4 and 10
  2. The required contact time for chlorine dioxide is lower
  3. Chlorine dioxide has better solubility
  4. Chlorine dioxide does not react with ammonia or ammonium
  5. It destroys THM precursors and increases coagulation
  6. ClO2 destroys phenols and has no distinct smell

BIOFILM REMOVAL AND CONTROL

A biofilm is a layer of microorganisms contained in a matrix (slime layer), which forms on surfaces in contact with water. Incorporation of pathogens in biofilms can protect the pathogens from concentrations of biocides that would otherwise kill or inhibit those organisms freely suspended in water.

Biofilms provide a safe haven for organisms like Listeria, E. coli and Legionella, where they can reproduce to levels where contamination of products passing through that water becomes inevitable.

It has been proven beyond doubt that chlorine dioxide removes biofilm from water systems and prevents it from forming when dosed at a continuous low level. Hypochlorite, on the other hand, has been proven to have little effect on biofilms.

COOLING TOWER TREATMENT

Cleaning and disinfecting cooling towers is essential for several reasons, most of which are well known. Clean pipes mean higher heat exchange efficiency, pump lifetime improvement, and lower maintenance costs.

Most people, however, are unfamiliar with the fact that cooling towers pose a possible health risk. The high temperature condition is ideal for the growth of several pathogen organisms (such as Legionella).

The usage of chlorine dioxide comes with several advantages:

  • It is a very powerful disinfectant and biocide;
  • It prevents and removes biofilm;
  • Unlike chlorine, chlorine dioxide is effective at pH between 4 and 10. No dumping and filling with fresh water required;
  • The corrosive effects of chlorine dioxide are minimal compared to the corrosive effects of plain tap water;
  • The bactericidal efficiency is relatively unaffected by pH values between 4 and 10. Acidisation, therefore, is not required;
  • Chlorine dioxide can be used as a spray. All parts, therefore, can easily be reached;
  • And, last but not least: less environmental impact.

POTABLE WATER DISINFECTION

Chlorine dioxide has been used for years in potable water disinfection (in the US since 1944). The need arose when it was discovered that chlorine and similar products formed some dangerous DBP’s (disinfection by-products) like THM (trihalomethanes).

Since then, many UK- and US-based water companies have started using chlorine dioxide. There are, however, more reasons to use chlorine dioxide:

  1. The bactericidal efficiency is relatively unaffected by pH values between 4 and 10.
  2. Chlorine dioxide is clearly superior to chlorine in the destruction of spores, bacterias, viruses, and other pathogen organisms on an equal residual base.
  3. The required contact time for chlorine dioxide is lower.
  4. Chlorine dioxide has better solubility.
  5. No corrosion associated with high chlorine concentrations. Reduces long term maintenance costs.
  6. Chlorine dioxide does not react with ammonia or ammonium.
  7. It destroys THM precursors and increases coagulation.
  8. Chlorine dioxide destroys phenols and has no distinct smell.
  9. It is better at removing iron and magnesia compounds than chlorine, especially complex bounds.

VEGETABLE WASHING

Chlorine dioxide is an excellent product for washing vegetables. The ability to kill spores, viruses, and fungi at low concentrations is essential.

Chlorine dioxide is a proven product that can be used to solve several food-related problems. It does not affect taste, odor, or appearance. It is safe to use and complies with food regulations. Below are some examples where chlorine dioxide has been applied:

  • Apples: Control of E.Coli and Listeria bacterias
  • Potatoes: Protection against “late blight” and “silver scurf”
  • Lettuce, Celeries, and Onions: Compared to hypochlorite, the vitamin C content resulted higher and the potassium content lower
  • Citrus Fruits: Protection against “green mould” and “sour rot” proved to be successful at several pH values, low concentrations and limited contact time

HOT AND COLD WATER SYSTEMS

The advantages of using chlorine dioxide with hot and cold water systems have already been shown above within the Biofilm and Legionella descriptions. There are, however, more advantages:

  1. The bactericidal efficiency is relatively unaffected by pH values between 4 and 10.
  2. Chlorine dioxide is clearly superior to chlorine in the destruction of spores, bacterias, viruses, and other pathogen organisms on an equal residual base (even cryptosporidium and giardia).
  3. The required contact time for chlorine dioxide is lower.
  4. Chlorine dioxide has better solubility.
  5. No corrosion associated with high chlorine concentrations. Reduces long term maintenance costs.
  6. Chlorine dioxide does not react with ammonia or ammonium.
  7. It destroys THM precursors and increases coagulation.
  8. Chlorine dioxide destroys phenols and has no distinct smell.
  9. It is better at removing iron and magnesia compounds than chlorine, especially complex bounds.

SCRUBBERS

Scrubbers are similar in design to cooling towers. The primary difference between the two is that scrubbers are pressurized systems, while cooling towers are vacuum systems. Scrubbers re-circulate water and spray it across the top of the system, counter-currently to the airflow. The function of re-circulating water is to absorb odor-causing species from the air.

Chlorine dioxide added to the re-circulated water reacts rapidly with odor-causing species that have been absorbed in the water, as well as those species that remain in the air. Usually, a very low chlorine dioxide residual, around 0.2 ppm, is sufficient to ensure odor control.