Technical Articles

by Jack Reiff

About the Author


Jack Reiff is president of Wet Tech, a laundry and wastewater treatment consulting firm based in Worcester, Mass. 01602 
Ph - 508-831-4229 Jackreiff@wet-tech.com

Table of Contents
  1. Ozone Science & Technology Minus the Myths
  2. Ozone Applications & Benefits of Ozone in Tunnel Washers
  3. Ozone Puts The Washroom On a Diet
  4. Ozone: A Natural Way to Purifiy Air and Water
  5. Cell Lysing – Destruction of Bacteria cell with Ozone
Ozone Science & Technology Minus the Myths

With the crack of lightening and the roar of thunder, Mother Nature goes about her job of cleaning up our environment. Step outside after a thunderstorm and smell the sharp, clean crispness in the air. This is carona discharge of an enormous degree in a natural setting. A walk in the sun, protected by the ozone layer in our atmosphere using some of the sun's light waves (UV) to protect us from other more harmful sun rays is another natural way mother nature works with ozone to benefit humankind along with other living species.

Ozone Applications & Benefits of Ozone in Tunnel Washers

The pace of change in design and advances in technology in the development of tunnel washers have, in my opinion, been as fast and furious as those of flight in the aircraft industry. Flight has "taken off," as have the design and development of tunnel washers.
My fond memories of and relationship with tunnel washers began in the mid-'70s when I was a chemical sales technician for Diamond Alkali Co. I was asked to set up the new Poensgen continuous wash system being installed in New Jersey at a joint hospital laundering facility. This was the first time I or most people I knew in the industry had ever heard of such a machine.

Ozone Puts The Washroom On a Diet

Adding O3 to the wash wheel can reduce operating hours, chemicals, water, and energy, consultant says. 
Reprinted with permission of Textile Rental magazine, the official publication of the Textile Rental Services Association of America.

Ozone: A Natural Way to Purifiy Air and Water

Ozone, a new ingredient in washroom technology, also can help improve washroom efficiency. A quick and effective oxidizer, ozone is part of the chemistry added to the break/wash cycle to remove the soil that is held by the alkali and detergents. In effect, ozone cleans up the water by cleaning the detergent chemicals so that they can be reintroduced into the wash wheel and continues to remove soil from the fabric. Ozone accomplishes
this by:

Cell Lysing – Destruction of Bacteria cell with Ozone
 

Ozone Science & Technology Minus the Myths - Ozone options, capabilities

There are several methods that can produce ozone. The natural way (as stated above) is carona discharge. There also is UV (ultraviolet) light, which happens naturally. This process (UV) is also known as the photochemical process of generating ozone.
Both methods can be reproduced by man in a mechanical/electrical manner. Another method is with electrolysis or electromechanical oxidation of water. Place electrodes in a tank of water and add an electric charge to excite the molecules. This releases ozone and oxygen at the anode terminal. No feed gas is required. A third process for generating ozone is with a cold plasma system. This process involves a glass tube filled with a mixture of inert gases and a small amount of mercury. An energy tube similar to a fluorescent light runs through the tube of inert gases and causes the gases to ionize at a low energy level and low temperatures.
There are various adaptations, combinations and arrangements of these generators that can enhance their applications in laundry and wastewater treatment, as well as keeping them within an efficient and economical operation. Some of these systems have some inher- ent design and operational restrictions that do not make them as desirable for use in laundry and wastewater treatment as the Carona discharge and UV methods.
All of these systems use a method of aggressive agitation to break up the oxygen molecules (O2) so that these molecules temporarily attach themselves to other oxygen molecules (O1), becoming (O3) ozone. One method of aggravation, carona discharge, is more aggressive than the UV light wave of ozone generation. These two systems, by design, almost establish the parameters for the present-day systems of ozone generation for our industry.
The history and facts of the benefits that the use of ozone offers humanity, especially in the healthcare, water treatment, waste treat- ment and the laundering of textiles have been discussed in previous articles. Documented data establishes the benefits of ozone in oxi- dation and sterilization, resulting in a quick return on investment (ROI) for ozone equipment.
Some pollutants can only be oxidized by ozone. For example, Cryptosporidium Parvum, a drinking water pollutant, is resistant to most chemical disinfectants, but is effectively destroyed by ozone. Some disinfectants act as a barrier to cysts but do not destroy them. Ozone eliminates them.
Flocculation is greatly enhanced; BOD, COD, FOG and other benefits abound with the use of ozone. It is important, then, to understand the manufacturing processes of ozone and making the application fit the product. This two-part series on the science and technology of ozone will deal primarily with the manufacture of ozone through the use of the UV light (photochemical process) and the Carona discharge methodology.

 

UV light (photochemical) process

Light comes in various colors based on the specific wavelength we can see. When atoms are exposed to high energy from any source, they tend to become excited and give off energy in the form of radi- ation. The nature of the radiation depends on the source, the excitation energy used and the media through which the radiation is travum UV is below 200 nm. Vacuum UV is strongly absorbed by air; the UV-C is primarily used to destroy organisms. The level of nm's in the UV-C range that inactivates organisms is in the range of 253.7. It is interesting to note that the ozone-forming and the ozone-destroying wavelengths of UV light coexist at approximately 254 nanometers. It is for this reason that UV generators also are used as ozone destruct units. UV generators are rated by their capacity to treat water at specific flow rates. The UV dosage is the major consideration and is the product of the radiation intensity and the exposure time as is expressed in microwatts per square cen- timeter. It is this dosage that determines the unit's effectiveness and not the watt input or the radiated output of the UV lamps. The dwell Mechanical Operation of an Ultraviolet System.
FDA and other agencies specify I-Line UV intensity meters for output verification. A UV sterilization/ozone generator can lose its intensity when sleeves used for pro- tection get cloudy from mineral content or particulate material in the water.
eling. The wavelength is measured as the distance between the peaks of a wave (angstroms) and the amplitude (height) of the wave. Light waves are measured with a nanometer and read in nm units.
The generation of UV radiation is through the use of discharge lamps placed in a glass tube with an inert gas. In this way, the UV process works much like cold plasma generation. The construction of the unit and its performance depends on several factors. The type of glass has one such effect on the wave. The glass can restrict the flow and intensity or distort the wave in some other way as it trav- els through the glass. The inert gases are another factor and are selected for the job at hand as well as the metallic substance, usual- ly mercury, to achieve a specific wave of light.
Visible light is at a wave length of above 400 nm's. UV radia- tion, which for practical purposes, can be divided into four general intensities, is below 400 nm's. The categories of the UV light are UV-A, which is between 400 and 315 nm. UV-B is between 315 and 280 nm. UV-C runs between 280 and 200 nm, while the vacume UV is below 200 nm. Vacuum UV is strongly absorbed by air; the UV-C is primarily used to destroy organisms. The level of nm's in the UV-C range that inactivates organisms is in the range of 253.7. It is interesting to note that the ozone-forming and the ozone-destroying wavelengths of UV light coexist at approximate- ly 254 nanometers. It is for this reason that UV generators also are used as ozone destruct units. UV generators are rated by their capacity to treat water at specific flow rates. The UV dosage is the major consideration and is the product of the radiation intensity and the exposure time as is expressed in microwatts per square cen- timeter. It is this dosage that determines the unit's effectiveness and not the watt input or the radiated output of the UV lamps. The dwell time (exposure time) of the contaminants in the reactor determines the elimination of the organisms. General exposure alone is not enough. The dwell time can vary based on water flow in volume and/or velocity. The organisms to be eliminated must be in the con- veying fluid and reside in the radiation zone long enough to absorb a lethal dose of UV light. For this reason most UV ozone systems must have a treatment chamber so that exposure to the UV is con- trolled. The UV lights are housed in a sleeve or jacket that is trans- parent to the UV radiation but acts as protection for the light source, as well as an insulator for the light to control the heat buildup.
The life span of the light source (the bulb) varies with age and the film buildup on the shell of the lamp. These two factors impede the proper generation of the UV light and interfere with the destruction of organisms. It is quite possible for a UV sterilizer/ozone genera- tor to lose its intensity when the sleeves used for protection get cloudy from the mineral content or particulate matter in the water. For these reasons, the FDA and other agencies are specifying I-line UV intensity meters for output verification. There are various lamp sizes, intensities, internal pressure levels and outputs that can be matched to the design demand of a particular situation. Energy in is energy out, so check the design specifications to determine if they fit your needs

Wastewater processing benefits

UV light works quite differently than Carona discharge generation of ozone. The method of operation with a UV light is to continu- ously expose the medium to be processed, whether it is air or water, through the high intensity light contained in the reactor tube. The light permeates through the medium and shines through any organ- isms that are in the air or water stream. The intense UV rays impact the sensitive RNA and/or DNA of bacteria, thus preventing the organism from reproducing. Bacteria, having a short life span, rely on rapid reproduction to flourish. UV rays essentially halt further growth or activity in these organisms. Unfortunately, since the UV light is only used within the small contact area, it does not provide residual disinfection in the water or air. One can see that the use of UV light is an effective tool, but one that does not prevent growth of bacteria unless it provides constant exposure. The ozone that is generated oxidizes the bacteria and particulate soil, thus destroying bacteria cells and preventing their reproduction. The ozone also oxidizes the soil or particulate matter, changing or destroying the chemistry of the soiling materials such as organic compounds. It is for these reasons and others that steps should be taken to ensure the purity of the UV generators, thereby ensuring the desired results.
Some real-world uses of UV technology as written about in High Purity Water Preparation by Theodore H. Meltzer and Water
Quality Products by Adam Donnellan of Sunlight Systems are well established. The use of UV in destroying water-borne diseases is well established. Its use in the pharmaceutical, food, beverage, cosmetic, healthcare, manufacturing, high-tech manufacturing, waste- water treatment, cooling towers and laundry processing also is well documented.
Although UV is used to generate ozone, it is also used as on off- gas control and ozone destruct unit, controlling the ozone use to those areas of need.
Food and beverage manufacturers use the ozone to destroy the organisms that grow around these products. TOC (Total Organic Carbon) reduction is quite popular, along with dye stuff removal, chlorine neutralization, the processing of fresh food, drinking water, air conditioning, cooling towers and heat exchangers. Most of all, the wastewater generated by laundries through wash processing is altered in so many ways that the benefits to the industry are significant.

The second part of this series on the science and technology of ozone will discuss the Carona discharge process in ozone generation. TR

PART 2 Carona Discharge
An overview of how ozone is created and harnessed for use in commercial laundries

What Mother Nature performs, science tries to duplicate and then works to improve upon. Ozone, created by a natural phenomenon rain, thunder and lightning provides so many benefits to mankind that science had to harness the energy and recreate the process. This seemingly simple process that takes place naturally in the environment has taken the industrial society a long time to perfect. When it comes to ozone you could say, "Agitation leads to aggres- sion and harnessed aggression leads to positive results." We recre- ate the process so that we can harness and apply ozone wherever possible.
Christian Friedrich Schonbein discovered ozone in 1840; in 1857 Werner Von Siemans developed a process for its general and industrial use. Experimentation and development continued in the search to improve on the generation of this fragile molecule that does so much, but readily decomposes back to oxygen.
Unhappy molecules
When stimulated (agitated) by either an electric charge or ultravio- let light (specific wavelength) the oxygen molecule (O2) breaks up and temporarily joins other oxygen molecules forming O3 (ozone), or other levels of ozone depending on the charge and feed source. These outside oxygen molecules are not happy in this new arrangement and seek to disengage themselves, creating an abundance of oxidizing power.
As stated in Part I of this series, there are several ways to produce ozone. The natural phenomenon of carona discharge, UV (ultravio- let light), photochemical or cold plasma have all been improved upon by science and technology so that the process now is relative- ly inexpensive.
Ozone, unlike most other chemicals, has no natural resource or method of storage. Ozone is generated on site and due to its rapid decomposition, it can't be stored for extended periods.
Carona discharge, one of the generation methods cited above, requires the energetic excitement of molecular oxygen to redistribute itself into atomic oxygen in the form of O3. The silent arc discharge, also known as carona discharge or brush discharge, has become the preferred method of ozone generation when outputs 
 

above 1 gram/hour are required. (See exhibit 1) A carona discharge generator can take on many forms, shapes, sizes and ozone outputs. The required components of a basic silent arc carona discharge ozone generator are:
a) two electrodes separated by a gap b) a dielectric material inserted into the gap c) a feed-gas flow containing oxygen inserted into the gap d) sufficient voltage potential between the two electrodes to cause a current flow through the gas.

The electrodes can be flat, tubular or in any other shape to provide a parallel position for energizing.
A typical ozone generator may take the form as shown in exhibit 2
This is a simplistic design that exhibits all of the attributes of a basic ozone generator.
In exhibit 3 (next page) there is an ozone cell that has been con- structed from laboratory glass and formed to provide the proper design for ozone generation and to be able to direct the ozone con- centration for specific uses. This is an early design that has been improved upon and simplified for today's ozone generators. The reliability, performance and efficiency of the ozone generator depend on several factors. Since more than 80% of the applied electrical energy is converted to heat, the materials used in con- structing the generator must be heat resistant. The heat generated must also be removed quickly and efficiently from the area or else the heat will accelerate the decomposition of the ozone generated. Some ozone generators are water cooled. This method for small ozone generators can be costly, and in a laundry setting it can reduce the utility savings that are part of the rationale for using ozone.
 

 

Another method of cooling is through an airflow and/or refrigeration. With the proper use of airflow, heat is reduced and utility costs are not increased. Many manufacturers use heat sink devices in their design around the ozone components to direct heat away from the unit.

A process of balance

The generation of ozone is a process of balance and equilibrium. It is a process where ozone is being generated and yet destroyed con- currently. Feed gas decontamination is critical for good ozone generation. Heat, particulate matter, moisture, feed-gas flow (volume), pressure, vacuum, water conditions and other variables will affect the ozone quality and percentage of concentration.
This is one of many reasons that clean dry air or oxygen should be used in the generation of ozone. The U.S. Environmental Protection Agency (EPA) suggests that minimum moisture content below 60 dew point (frost point) should be maintained with the feed source.
Clean air, free of particulate matter, provides for maximum oxygen content in the volume of air being supplied as a feed gas. Dry air, again to maximize volume flow, also eliminates the potential for nitrous oxide development when the carona arc energizes the feed gas. Nitrogen oxide, converted to nitric acid, is detrimental to the operating equipment and catalytically destroys the ozone.
The selection of the dielectric material is critical in the performance, output and life of the generator. When considering the dielectric, it should be rated based on the continuous electron bombard- ment necessary to generate the desired ozone output. This same concern must be applied when selecting the electrodes.
To provide a sufficient volage potential between the electrodes to generate the ozone, a transformer is incorporated into the system to step up the voltage and operate between 10,000- 25,000 volts at low amperage. This voltage can vary based on the design characteristics for the ozone application. Some trans- formers are of the dry type where others can be encased in oil or be filled with silicone or other heat- control material to maintain low operating temperatures. The line voltage to the transformers can
be 120 VAC, 230 VAC or 440 VAC in single phase or 3 phase at 50- 60 hz.

Better than chlorine

Ozone is a gas that is virtually colorless and has an acidic odor. (That's ozone that you smell at the back end of your photocopier.) The gas has an electrochemical oxidation potential that is quite high and is superior to chlorine or other sanitizing products as shown in exhibit 4
The high oxidizing potential allows ozone to break down organic compounds that chlorine cannot. The pungent odor makes the presence of ozone immediately noticeable but not necessarily harmful. Most people can detect about 0.01 ppm in the air. This is well within the general comfort level of individuals. Symptoms that are experienced with concentrations at .01 to 1 ppm are headaches, irri- tation, burning of the eyes or respiratory discomfort.
When compared to the same exposure to chlorine, you will find that an exposure to 1,000 ppm of ozone for 30 seconds would be mildly irritating but the same exposure to chlorine is often fatal.
Ozone will attack and decompose organic and inorganic materials. Ozone attacks the molecules that bond many soils to the fabrics that we wash so it enhances the removal of these soils from the fab- ric. The oxidation of inorganic material helps in the process of treat- ing soluble soil, making it insoluble so that it can be precipitated out of solution. This attribute is the basis for top-end wastewater treatment.
The potential applications, at present, seem unlimited. The untold advantages of ozone include environmental, economic and health benefits.

 

 

 

 

 

 

 

 

 

 

 

 

 



 

Harnessing and applying ozone

Now that we have produced the ozone, how can we harness and apply it for practical benefits? One of the simplest ways would be to use a venturi injector. This device, set into the stream of the water that is in use and to be infused with the ozone, creates a pressure differential from the inlet to the outlet side of the device. This pressure differential creates a low pressure (vacuum) in the outlet flow of the water. This low pressure or vacuum is the suction for the ozone feed line into the water flow. This type of application should be designed properly so that the loss of ozone in the vacuum does not inhibit the designed function of the ozone. The venturi system requires a water flow under pressure.
Another method would be with the use of a sparger, which allows the ozone to bubble into the water, under pressure, for dispersion in the water. This method provides for large and small bubbles of ozone to be applied and allows for off gassing unless destroyed.
Specifically designed diffusers, in my opinion, would be the most effective and efficient method of applying ozone in the wash liquor.
The ozone bubble size is controlled and will minimize off gassing. Bubble-size control is more effective when considerations are given as to the designat- ed task of the ozone. Controlling bubble size also aids in the efficient dispersion of the ozone into the water. It is smart to remember that one size does not fit all applications.
Ozone is a chemical that when used properly can greatly enhance washroom technology and produce sound environmental and economic results.

 

 

 

Applications & Benefits of Ozone in Tunnel Washers

The pace of change in design and advances in tech- nology in the development of tunnel washers have, in my opinion, been as fast and furious as those of flight in the aircraft industry. Flight has "taken off," as have the design and development of tunnel washers.
My fond memories of and relationship with tunnel washers began in the mid-'70s when I was a chemical sales technician for Diamond Alkali Co. I was asked to set up the new Poensgen continuous wash system being installed in New Jersey at a joint hospital laundering facility. This was the first time I or most people I knew in the industry had ever heard of such a machine.

Then-new technology heralded new era

Arriving on the scene with my titration kit and the confidence of knowing washroom technology, I approached this task with a lot of enthusiasm. What I saw when I entered the laundry was six long pipes with large, aircraft-type inner tubes at the outlet of each pipe. The inner tubes were the extractors or press modules for the processed linen. The tunnel washer was designed as a tube (pipe) into which the linen was fed in a rope-like fashion. In this way, the leading piece of linen pulled the linen behind it, forming a rope-like continuous source. The unit was able to wash items that could be linked together like threads. One can sense the problem that would be caused if the feed line parted. The feed process had to be restart- ed to get the line going again.
The linen passed through several treatment baths in the wash process, which was similar to what we see in modern tunnel systems. Sheets, towels and pillowcases moved along nicely and this proved to be a perfect match for the central hospital laundry, with many pounds of like items.
The water moved in a counterflow arrangement to the linen and chemicals were added through a hollow tube with a cup on the dip end. The feed water was interrupted at certain locations so that soil could be drained off or water could be introduced to optimize the wash, bleach, rinse and finishing of linen.
The hollow tube that delivered chemicals in this system was attached to a rotating cam with a measuring cup at the end. The measuring cup and arm moved to allow the cup to move into and out of the chemical supply tank. The range of dip and lift deter- mined the amount of chemical used. The cup lifted to allow chem- icals to flow through the hollow tube in to the specified area. Chemical concentrations were adjusted during the mixing process, where they were converted from powder to liquid.
We established a titration system for almost all chemicals, including for the sour, to guarantee performance (the sour titration was a reversal of the break titration, which used a known standard concentration of alkali solution). Based on the cam-to-arm configuration, which was changeable, the dip and amount of chemical being used was adjusted for the wash formula.
As stated earlier, there was a large, rotating inner tube configura- tion at the finishing end of the tunnel washer similar to that of an airplane inner tube. This tube rotated, pressing and pulling the linen feed line through the Poensgen tunnel, pressing out water so the linen could be collected in baskets and brought to ironers for fin- ishing.
This was the dawn of a new day for me and for the laundry indus- try. The next phase of tunnel development I was exposed to was in the form of the Voss Archimedia, a bottom-transfer tunnel installed at the Consolidated Laundry facility on Eagle Street in Brooklyn, NY, followed by one that went into the laundry plant in Norwalk Hospital, Norwalk, CT.

Designs and vendors multiply

These units, based on the Archimedia screw, had chemical supply tanks with dosers to get the chemicals, which were under pressure, into the washer. The chemicals were injected into a central hub that served several supply tubes and ran the length of the tunnel to an opening at the proper location for that chemical's use. The chemcal volume and strength could both be adjusted at the doser. The feed location could be changed within specified parameters so that chemicals could be added per the supplier's requirements.
The Voss Archimedia washer had a control card that moved up and down to regulate the formula. Chemical technicians cut the cards to regulate the wash formula. When formulas were to be changed, such as when going from sheets to OR linens, a new card had to be installed, much like the programs of earlier conventional washing machines. It was at the Norwalk Hospital, with the consent of laundry manager Jim Bauman, that I designed an electrical switching device that could activate different control tracks so that the program could be changed without removing the program card. This sped things up for Jim and opened a door for Voss.
As the technology matured, so did equipment design. The basic counterflow remained the same but wash transfer concepts changed. The bottom-transfer screw led to the top transfer and many other designs.
As time passed, greater technological sophistication improved wash times and quality, press performance and load transfers. Efficiencies improved and the tunnel washer came to be seen as an industry fixture. Designers incorporated double shells, zoned com- partments, full compartments, splitter tanks, boosting systems and quick water drain/replacement transfers. So much has been done to improve each approach and technique that the customer can now choose from a vast array of tunnel washers.
It is not my intent to endorse or recommend a particular tunnel washer. There are many manufacturers that have a tradition and history of excellent design, manufacturing and performance that speak for themselves.

Ozone breaks Sinner's Circle paradigm

Tunnel washers have come a long way. What is lacking now is the proper application of ozone in the wash process to improve the efficiency, performance and quality of tunnel washers.

 

 

 

 

 

 

 





The application of ozone as a chemical enhancer encompasses many critical aspects of washroom formulas. An understanding of washroom technology is needed to facilitate good washroom pro- cedures. Anyone can wash lightly soiled items quite effectively and somewhat efficiently with low levels of ozone. The challenge is to take full advantage of the synergy developed when ozone is used to enhance washroom chemistry for all levels of soil.
Consider a scenario in which ozone is used with cold water when hot water is turned off. What effect does this have on the removal of body soil, food, beverage or other soils that flow at body tem- peratures of at least 98°F? Would the use of cold water require the use of more chemicals or more time?
Ozone, described chemically as O3, is the triatomic form of oxygen. It is very unstable and highly corrosive. Ozone has a short life cycle and decomposes to oxygen (O2) without leaving a residue. This high oxidation power with a chemical valence slightly on the acid side is the basis for various applications in the wash. This super oxygen enhancer does special things for washroom chemistry. However, an enhancement is not a replacement for chemical applications.
To date, ozone is the one product that can be utilized in a wash formula that will reduce but not eliminate all other factors in washing. A chemist by the name of Sinner developed the Sinner's Circle theory of washing in which time, temperature, mechanical action and chemicals controlled the wash formula. It was thought that if you increased one factor, you could decrease the others, as depicted by a simplified pie chart.
We know from experience that this is not true. We need dilution in the wash formula to rinse down and eliminate soil from the fab- ric. We need the same dilution to reduce residual chemicals in the many critical aspects of washroom formulas. An understanding of washroom technology is needed to facilitate good washroom procedures. Anyone can wash lightly soiled items quite effectively and somewhat efficiently with low levels of ozone. The challenge is to take full advantage of the synergy developed when ozone is used to enhance washroom chemistry for all levels of soil.
Consider a scenario in which ozone is used with cold water when hot water is turned off. What effect does this have on the removal of body soil, food, beverage or other soils that flow at body tem- peratures of at least 98°F? Would the use of cold water require the use of more chemicals or more time?
Ozone, described chemically as O3, is the triatomic form of oxygen. It is very unstable and highly corrosive. Ozone has a short life cycle and decomposes to oxygen (O2) without leaving a residue. This high oxidation power with a chemical valence slightly on the acid side is the basis for various applications in the wash. This super oxygen enhancer does special things for washroom chemistry. However, an enhancement is not a replacement for chemical applications.
To date, ozone is the one product that can be utilized in a wash formula that will reduce—but not eliminate all other factors in washing. A chemist by the name of Sinner developed the Sinner's Circle theory of washing in which time, temperature, mechanical action and chemicals controlled the wash formula. It was thought that if you increased one factor, you could decrease the others, as depicted by a simplified pie chart.
We know from experience that this is not true. We need dilution in the wash formula to rinse down and eliminate soil from the fabric. We need the same dilution to reduce residual chemicals in the fabric. We know that if we increase chemical use, we must increase dilution to reach the desired effect on the fabric without increasing the neutralized salts that might be left after treatment. This all must be taken into consideration when working with a counterflow sys- tem as well as with a conventional washer.

Corona discharge more popular than UV

Ozone, the super oxygen enhancer, is the chemical enhancer that accomplishes the tasks noted above and reduces all aspects of the wash criteria as depicted in the Sinner's Circle pie chart. Ozone is unique in another way. Through a process called cell lysing, ozone molecularly ruptures and disperses microorganisms.
In this way, microorganisms such as bacteria, viruses, mold, fungi, and algae are dealt with more effectively than by other bio- cides such as chlorine. They are not just dead; they are destroyed, preventing reactivation or the development of a resistant strain of the microorganism. The sanitizing ability of ozone, 3,000 times more effective than chlorine, makes it the chemical of choice in water treatment.
Not all ozones are the same. The percentage of concentration, the flow rate, the air source, the application and many other aspects of ozone use will yield different results. It is important to remember that ozone is highly corrosive and is an aggressive oxidizer that attacks most materials. Steel, brass, bronze, petroleum hydrocar- bons, plastics, cotton, polyester, chlorine and many other materials will break down in the presence of ozone. It is therefore important to know the levels of ozone being used, the concentration, the makeup
of the air source and the life cycle of the ozone because these are crit- ical to its performance (Note that EPA Bulletin #832-F-99-063 states that the dew point of the feed gas must be -60°C [-76° F] or lower to manufacture ozone without a by-product of nitrogen oxides such as nitric acid.).
The two methods I know of for creating ozone are ultraviolet (UV) light or corona discharge. These methods excite oxygen mol- ecules so that they jump around and attach themselves to other oxy- gen molecules, making O3. The O3 is not too happy and looks to go back to its more stable form of O2, so its life cycle is very short. The ozone life cycle is dependent on the concentration of the ozone, the temperature of its surroundings, whether there is a vacuum, where it is to be used and the level of soil.
It appears that the life cycle of ozone is very short when exposed to high temperatures because the gas becomes excited. The ozone life cycle is extended for a brief time in cold water but when used in a vacuum, ozone dissipates rather quickly because it expands to fill the vacuum. How one answers the questions of how and where to use ozone are critical to developing an efficient and effective wash formula.
Most laundry applications utilize corona discharge technology because it is easier to control, has a smaller footprint and starts when electric current crosses the feed air system. This is much like a bolt of lightning passing through the atmosphere in a rainstorm, generating ozone. You can sense a crispness in the air and a clean, fresh smell. 
Cold-water rinse sustains O3 levels
When developing a wash procedure for cleaning soiled fabrics in a tunnel washer, one must consider the operating conditions of the tunnel. All the tunnels I have come across operate with the main water flow coming through the rinse chamber. This flow determines the speed and fullness of the rinse and starts to reduce the wash bath temperature for treatment. Most units have two or three compart- ments for the rinse operation and an incoming flow of about 55 gal- lons per minute.
A basic wash formula will start with a transfer cycle of about 1.5 minutes, comprised of one minute for washing and 30 seconds for transfer to the next chamber. This process is variable and can be adjusted to deal with high soil levels. All equipment fits this format in the introduction of the main supply of water.
Most tunnel washers are broken into sections or operation zones. Starting at the soiled linen inlet, there is usually a pre-wash zone, which drains to the sewer. The next section would be a wash zone made up of several chambers that transfer to the bleaching zone. The water counterflows from the last bleach section, down through the wash zone and into the drain.
The wash is then transferred to the rinse zone, which is also made up of several chambers. This water drains into a split or redirect supply tank. From the rinse zone, linen is transferred to treatment compartments for final chemical finishing before going to the press.
To summarize, we have a prewash area, a wash area, a bleach area, a rinse area and a final treatment area before going to the press. The uniqueness of the counterflow system in making full use of water starts in the rinse zone. This is the point at which fresh water is introduced into the tunnel to rinse linen. This is the clean- est that the water will be. This rinse water is usually drained into a transfer area where the water is then divided between the bleach zone and the pre-wash area.
In the bleach zone, where ozone use is eliminated, the process is similar to bleaching in the clear due to the counterflow characteris- tics of the wash. The prewash area is usually where rinsing and chemistry begin removing soil from the fabric. Steam is typically injected to raise the temperature for the desired soil removal. Although dirty water drains from this section, a good portion of the water is transferred with the linen into the next compartment, where the washing begins in earnest. More chemicals are added and tem- peratures are increased for effective soil removal. This load is trans- ferred along from several wash pockets through several bleach pockets. In the wash zone, ozone helps reduce the soil level of the wash liquor by oxidation, thus improving wash quality.

Ozone cuts post-bleaching chlorine levels

After going through the rinse cycle, the load is transferred to the treatment zone, which can also be made of one or more compart- ments. At this point the sour, bacteria treatment, starch or other desired finishing agents may be added. This last compartment drains to a small tank around the press or to other collection areas.
With this brief description and understanding of tunnel-washing concepts, you can see that the application of ozone raises many questions. The use of standard or other chemicals does not keep ozone from providing its many beneficial properties, but raises the bar on chemical applications. 

 

 

Ozone Puts The Washroom On A Diet

Adding O3 to the wash wheel can reduce operating hours, chemicals, water, and energy, consultant says. By Jack Reiff 
Reprinted with permission of Textile Rental magazine, the official publication of the Textile Rental Services Association of America.

Dilution is the solution to pollution" was acommon saying in textile rental and other industries that depend on water for processing. The statement may be true, but it is a costly solution considering the price and/or scarcity of water and the expense of sewage disposal in many areas.

Dilution does, however, play an important role in washroom chemistry that is often ignored in wash formula discussions. But a common test process, chemical titration, explains the dilution process and provides an opportunity to understand how a new ingredient ozone can put the entire wash process on a diet.
 

 

t wouldn't be washing without dilution 
 
The chemical industry has developed a number of products and laundering techniques to remove soils from all types of fabrics that are safe and effective in cleansing the fabric without causing excessive fabric degradation. Current methods of chemical soil removal in the wash formula are emulsification, saponification, lubrication, flocculation, neutralization, oxidation, and color alteration. The general theory of washroom soil removal promoted by the chemical industry includes four processes time, temperature, mechanical action, and chemical action. The theory states that changing one process affects all of the other processes. This is true. And taking the theory at face value should mean that increasing chemistry allows for the reduction of time, temperature, and mechanical action. This, however, isn't true because the theory ignores the process of dilution, which is necessary to rinse away soil that has been dislodged by the chemicals and to remove chemicals from the wash liquor to prepare it for the next chemical phase of the wash formula. In a wash formula, chemicals (alkali and detergent) are added based on soil
level and wash wheel capacity. The resulting alkali activity establishes the parameters to bring the alkalinity of the wash liquor to specific levels for different activities: Removing soil, leaching or removing stains, neutralizing, or adding fabric treatments. The pH of the wash liquor, which is based on the amount of alkali added, is measured by titration. This analytical process uses amounts of acid of a known strength to neutralize and measure alkalinity of an unknown quantity. For example, if alkali added to the wash for medium soil creates a titration of 18 drops of normal acid in the wash process, the titration sequence might be as shown in Exhibit 1 (page 67). As the exhibit indicates, water levels (dilution) affect the titration arithmetically because of the water and chemicals retained by the fabric. High-water operations reduce the titration by about one-half from the previous step; low- level operations reduce titrations by about one-third. If, according to the theory, more chemistry is used to remove and suspend increasingly heavier soils, then time, temperature, and mechanical action should be reduced. However, the situation is just the opposite—the more chemicals used, the more water operations that are needed to reduce chemical and soil levels. And more operations require more mechanical action, which leads to more electrical use, longer operating hours, and more wear and tear on equipment and textiles.
This negatively affects the bottom line. An equally unacceptable solution is to rely on chemistry to neutralize the alkalinity of the wash formula. This produces neutral salts that stay in the fabric, creating wash formula problems and user discomfort. But by including dilution in the traditional

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

washroom technology pie, operators can develop formulas that achieve the most efficient use of time, temperature, mechanical action, and chemical action. Employing high-level rinses allows for the greatest dilution of dissolved materials, which means more soil can be separated from the load and drained away. High- level rinses also create a higher ratio of water removed by draining water retained in the textiles, allowing for a higher percentage of materials, including Alkali, to be removed at each rinse step. By progressive dilution, high level rinses eliminates all but a very small amount of dissolved and suspended materials from the load (see What You Should Know About Laundering and Textiles
by Eugene Smith, Ph.D. and Pauline Mack , Ph.D.;77-79).

 

 

How ozone can improve the process

Ozone, a new ingredient in washroom technology, also can help improve washroom efficiency. A quick and effective oxidizer, ozone is part of the chemistry added to the break/wash cycle to remove the soil that is held by the alkali and detergents. In effect, ozone cleans up the water by cleaning the detergent chemicals so that they can be reintroduced into the wash wheel and continues to remove soil from the fabric. Ozone accomplishes
this by:
• replenishing oxygen in the wash water;
• decomposing fats, oil, and grease; 
• preventing redeposition of soil; 
• softening the wash water; 
• purifying the wash water; 
• working like an oxygen bleach; 
• requiring lower wash temperatures; 
• removing soil attached to the wash chemicals;
• deodorizing the wash liquor and vapor.
Ozone is added to all of the operations of a wash formula to continually clean the wash liquor, putting dilution on a diet. Ozone chemistry is simple: The three oxygen atoms that bind together by an electrical input to form O3 are unstable and have an affinity for almost any atoms other than a pair of oxygen atoms.
n the wash wheel, the third oxygen atom jumps ship and joins with a carbon atom to form carbon dioxide (CO2) or with other nonorganic atoms to form oxides. This process makes wash water cleaner by reducing soil levels and making chemicals become more effective. Cleaner water allows for formulas that use:
land peroxide instead of chlorine for bleaching (this enhanced oxygen technology has a synergy with peroxide; ozone and oxygen bleaches provide superior results with less color degradation than chlorine bleach). An added benefit is that ozone improves the quality of the wastewater going to the sewer; both because it helps reduce the concentration of wash chemicals and because it acts as a pretreatment for the wastewater. Ozone technology still is in refinement of development but has proven to be an effective additive to the wash process. Used correctly, it can be one tool in the ROI
arsenal for the laundry industry. TRess chemicals fewer water operations,shorter wash time, lower water temperatures 

 


 

 

 

 

 

 

 

 

 

 

 

 

 

 

REDUCE, REUSE, RECYCLE, and TREAT; these have been some of the major tenets of our envi- ronmental survival plan. When looked at closely, we can see that REDUCE, REUSE AND RECY- CLE (R3), combined with the proper applications of ozone (O ), offer a balanced formula in wash-
Every businessperson is interested in operating efficiently, effec- tively and profitably. Labor leader Samuel Gompers (1850-1924) once said, "The worst crime against working people is a company which fails to operate at a profit." What you do in a positive way to affect the bottom line will impact profitability.
We have heard many war stories about the benefits and short- comings of ozone in treating laundry wash water. It's known and accepted that all swimming pools used for the Olympics are treated with ozone, rather than chlorine. Most of our bottled drinking water and that of major communities, like San Francisco, treat drinking water with ozone. Air conditioning systems use ozone for chemical reduction and prevention of Legionnaires' disease. Hot tubs, auto- claves and even an experimental process in Europe to stabilize AIDS (HIV) make use of ozone. Ozone destroys bacteria and virus- es through a process called "Lysing." Bacteria is not simply weak- ened or dead, they are gone. Most airborne bacteria are actually destroyed, thus removing odor and improving the environment.
We can all appreciate the reluctance of many people in our indus- try to replace other chemistry with that of ozone. We hear about mass transfer, having the proper pH and temperature much like enzyme applications affecting the proper results of these prod- ucts. Many of those stories may be circulated by those who benefit from not using and economical chemistry system in the washroom or in the wastewater treatment system.
The laundry industry is reluctant to use ozone in its operations. Whatever the reason, perhaps the problem is not with ozone but with the application of ozone in the washroom. It could be a case of the right tool with the wrong mechanic.

Ozone in action

Let's look at the facts about ozone. Conventional secondary wastetreatment methods do not remove all dissolved and suspended con- taminants. To improve the COD (Chemical Oxygen Demand) and destroy organic contaminants, surfactants and bacteria, an oxidation purification treatment with ozone offers many advantages. Ozone's high reactivity permits oxidation in a continuous process breaking down many compounds while removing color and odor. This tech- nique has roughly doubled the rate of reduction of COD or total organic carbon in the water medium.
1)The high oxidation power of ozone (disinfection, control of DBP's, taste, and odor) also enhances the downstream coagulation, flocculation and filtration process. This process is sometimes referred to as micro flocculation. When this process occurs, there may be benefits in lower chemical dosage, longer filter runs, high- er filtration rates and or lower filtered water turbidity. 2) This process also reduces or eliminates the VOC's in the water.

An eco-friendly chlorine alternative

Our rapid population and economic growth have placed increased demands on our water utilities. In some areas of California, people are selling off their water rights because of industries' growing demand for water. Increasing water production requirements coupled with rigorous quality standards for the finished treated water present more challenges. Disinfection requirements set forth in the SurfaceWater Treatment Rule along with other criteria prompted a major shift to ozone and other strong non-halogenated oxidants to replace chlorine. Ozone and like processes offer additional benefits including complete or partial oxidation of color, manganese, synthetic organic chemicals along with taste and odor-causing compounds. Enhanced flocculation, coagulation and sedimentation are some additional benefits.3, 4

NASA, Army success stories

The results of work accomplished at the John F. Kennedy Space Center, Cape Canaveral, FL, indicate many benefits from ozone applications as a water treatment replacing conventional chemical treatment for Cooling Towers. The results at the Jet Propulsion Laboratory in California considered most reliable for a three-year period test are most favorable in the use of ozone in place of con- ventional chemical treatment. The various sizes of the towers were 75, 250 and 350 tons. The conclusions were:
• Ozone was an effective treatment.
• Cooling Tower drift was environmentally acceptable.
• Chemicals eliminated that caused environmental contamination.
• Removed & prevented scaling deposition. Precipitated out calcium and other metallic ions as a fine sandy deposit.
• Metal surfaces were passivated to inhibit corrosion.

The ozone treatment was not considered as a dangerous poison because it could be easily detected by smell at very low concentrations.5, 6, 7
The U.S. Army at the Rocky Mountain Arsenal is decontaminat- ing this 17,000-acre facility of munitions chemicals, pesticides and a variety of volatile organic compounds (VOC's), as well as di-iso- propylmethylphosphonate (DIMP), an intermediate product of chemical manufacturing. This process at a much lower cost than the usual procedures utilizes a combination of ozone and hydro-gen peroxide as a variation of advanced chemical oxidation to gen- erate hydroxyl radicals that degrade contaminants. Iron, man- ganese, cyanide, and other soluble soils are either broken down to nitrogen, oxygen, carbon dioxide or other components and dissi- pated. Contaminants are also made insoluble for easy removal by other methods.8, 9

Effective wash liquor treatment

The laboratory study of ozone washing by Jack A. Turner con- firmed other aspects of washing that have been professed for many years. I am a firm believer in a process of washing the fabric clean, and then treating the wash liquor as a separate entity. When ozone is used in the wash wheel, whether it is from an ozone-saturated water supply, or by injecting the ozone directly into the wash wheel to effect soil removal, you run the risk of fabric damage, equipment damage and off gassing of the ozone. Ozone in direct contact with the fabric, whether it is natural or synthetic, has a detrimental impact on the break strength of the fiber.10 This process was used in the 1980s to get a stone washed effect on blue jeans without the use of stones.
A good wash formula using regular wash techniques of saponifi- cation, lubrication, emulsification, suspension, flocculation and bleaching will remove the soil from the fabric resulting in good stain removal. The wash chemistry, after accomplishing the above tasks, keeps the soil in suspension for removal by dilution. The ozone takes care of disinfection while assisting in the normal wash chemistry.

Dilution: new pie chart parameter

We have all seen and heard about the pie chart that refers to wash- room practices. This pie chart 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, that throughout this process, there are always references to the function of dilution. Dilution is the process of diminishing the chemical strength or concentration by admixture of water.
I suggest adding the function of dilution 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 dissolve 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 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 formu- la, 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 quality and enhances the ozone in its attack on 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.

Better waste water management

When ozone is applied to the wash liquor, I've 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 reenter 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 effect- ing 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 that eliminates off gassing during the wash cycle.
The enhanced oxygen from the ozone application reactivates the chemistry of the wash process making the use of high temperatures an unnecessary part of the procedure. Wash temperatures of 120oF to 135oF, 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 counterproductive 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 (98oF). 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 bene- fits.
The benefit of ozone in the wash does not stop at the drain. Ozone can be very beneficial in the waste stream and water reuse system. The high oxidation capacity of ozone aids in the process of coagulation, flocculation and filtration. It attacks soil and decom- poses much of it to air, water and carbon dioxide. Ozone bleaches out color and removes odor. It makes some soil insoluble for easy removal, drops out some metals, reduces BOD, COD, TSS and total organic carbon along with many other compounds found in the waste stream or equalization tank.

An environmentally sound, competitive edge

The mechanics of installation of an ozone system appears to be quite simple. Many people are fooled by the process. An under- standing of ozone and how it works in the washroom is very impor- tant to having a successful operation. The balance of ozone volume and concentration or intensity applied properly to the wash formu- la is critical. The total operation and understanding of soil classifi- cation, wash formula, wash chemistry and the effects that all of this has on the wash and effluent system of the plant determines the pay- back and level of aid in complying with environmental regulations. The right tool in the wrong hands doesn't help the bottom line.
Ozone, though it's been around since the 1870s, is still in its infancy. A lot of research is presently going on with ozone applica- tions in many differing fields of service.
Ozone, as one of the building blocks of a comprehensive treat- ment system enhances your laundry operation, provides air and drinking water purification along with other multiple benefits that do not require continuous operator monitoring.
To stay competitive in today's market, you must work within the environmental laws. You must remain flexible in your approach to meet changing demands, while providing a good quality product and reliable service from a profitable operation. Ozone, when applied properly, can serve as a helpful tool in meeting these commitments. TR 

 

 

Cell Lysing – Destruction of Bacteria cell with Ozone
 

 

 

 

 

 

 

 

 

 



 

 

 

 

Bacteria Pathogen Reduction 

1 - Computer generated image of a bacteria cell
2 - Close-up of ozone molecule coming into contact with bacterial wall
3 - Ozone penetrating and creating hole in bacterial wall
4 - Close-up effect of ozone on cell wall
5 - Bacterial cell after a few ozone molecules come into contact
6 – Destruction of Cell Molecular structure from Ozone exposure.

 

Note-

When based on 99.99% of bacterial concentration being killedand time of destruction

ozone is:

  • 25 times more effective than HOCI (Hypochlorous Acid)

  • 2,500 times more effective than OCI (Hypochlorite)

  • 5,000 time more effective than NH2CL (Chloramine)

  • At least ten times more effective than Chlorine & safer with chemical reactions or by-products

 
 

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