- Created on Tuesday, 03 September 2002 02:41
- Written by Jack J. Reiff
Applying ozone (O3) to the wash formula, the waste water stream and the pre-treatment system, can reduce operating hours, chemical, water and energy costs. In part two of this three-part series we’ll be taking a look at how ozone works.
We have all seen and heard about the pie chart that refers to washroom practices. The pie chart that is often referred to states that “Washing is a Function of Mechanical action, Time, Temperature and Chemistry ". Chemical companies have been stating that if we increase one function we can decrease the others. When we look at the pie chart it appears to be true.We all know though, the function of dilution is always referred to throughout this process. Dilution is the process of diminishing the chemical strength or concentration by admixture of water.
I would like to suggest that the function of dilution be added to the pie chart. Dilution, the fifth parameter of good washroom technology, now presents a balanced approach to washing. The problem is, under standard washroom formulation practices, when the chemistry is increased it usually requires more time to be dissolved in the wash liquor and more time, water and operations to dilute down for the sour or finishing baths. Therefore another wash parameter must be added to balance out the wash formula.
When ozone is applied to the wash formula we accomplish both aspects of this process. The ozone, chemically O3, is added to the wash liquor increasing the chemical activity of the operation. This increased chemistry activates other chemicals while oxidizing soils that are being carried by the wash liquor. The oxidized soil is broken down to air, water, carbon dioxide and reduced solids.
Throughout the wash program, when ozone is part of the formula, the oxidation process is continually diluting the bath by flocculation and coagulation among other chemical processes. Each bath of the wash process can be injected with ozone through a closed loop side arm injection system.
This system pumps a specific amount of wash liquor out of the wash basket and through a closed loop. While the wash liquor is moving through the loop, ozone is injected into the water stream through a venturi fitting. The low pressure in the venturi is a boost to the ozone inlet and enhances the ozone in its attack of the water contaminants. I liken this to a bleach operation in the wash process. If you were to attempt to bleach in a turbid bleach bath, the bleach would attack the soil in suspension rather than remove the stains on the fabric. The bleach takes the path of least resistance. To maximize stain removal the bleach bath should be clear.
Applying Ozone to the Wash Liquor
When ozone is applied to the wash liquor, I have found that it attacks the soil first before going after the surfactants in the wash liquor. In this process, the soil is removed allowing the break chemistry to re-enter the wash wheel in a rejuvenated state. Newly activated wash chemicals provide for reduced wash chemistry in the formula. The same process also reduces the soil contamination so you are effecting a dilution phase during the wash cycle and all other cycles, except the bleach, throughout the total process. By cleaning up the wash water in each cycle you then can reduce the number of cycles required for the total operation. The closed loop is designed at a specific length so that the ozone is consumed outside the wash basket within the closed loop which eliminates off gassing during the wash cycle.
The enhanced oxygen from the ozone application re-activates the chemistry of the wash process making the use of high temperatures an unnecessary part of the procedure. Wash temperatures of 120º F to 135º F, a point at which fabric swells or softens, makes soil removal easier. These are the temperatures I normally use in critical operations of the wash. Extremely cold water is counter productive to proper soil removal. Take for example a cut on your finger. You wouldn’t think of putting it under hot water to stop the bleeding, you would put it under cold water to stop the bleeding. Body fluid (soil) flows at body temperatures (98º F). Heavy soil, like aprons, bar mops and kitchen apparel usually require a higher temperature in any case.
Ozone, as stated above, destroys chlorine bleach through some chemical changes. This is another reason why the saturated water system is not practical. If the wash water was saturated with ozone in a supply tank and was then transferred to the wash wheel for a bleach operation, the chlorine would be made ineffective for stain removal. Bleaching with ozone during the wash cycle is easier when you control the application of ozone by cycle, time and amounts for the best wash.
The use of hydrogen peroxide bleach in conjunction with ozone can be a very effective stain removal tool when used properly as stated earlier. There is a synergy between these two chemicals, hydrogen peroxide and ozone that multiplies the individual benefits.
Jack J. Reiff is president of J. Reiff Consulting, Inc., doing business as WET - TECH, The Ozone People. A Washroom Technology Company specializing in washroom chemistry, water, water Reuse, Waste water & OZONE Treatment Systems, WET-TECH is based in Worcester Ma. He can be reached at www.wet-tech.com or # 508-831-4229.
Next Month we’ll take a look at some ozone success stories and the benefits of using ozone in the waste stream and water reuse system.
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