Ozone is rapidly becoming the ‘oxidant of choice’ in commercial laundry facilities. Many benefits await organizations that adopt this new ‘green’ approach to the age-old chore of washing linens.
The reasons to make the switch from traditional oxidizers (and persistent contaminants) such as chlorine include the following:
- drastic reduction in energy cost by elimination of hot water
(ozone cleansing works best in cold water)
- substantial reduction in the amount of water used
(due to need for fewer rinse cycles to remove chemicals)
- ability to recover and easily reuse a large percentage of water
- operators report fabrics washed in ozonated water feel better and wear longer
These are but a few of the compelling reasons that enterprises with commercial laundry facilities, such as hotels, resorts and hospitals are moving to this new technology.
Improving Ozone Wash Effectiveness
Our research indicates that precise, consistent and reliable control over the amount of dissolved ozone in the wash mix produces the most consistent finished product. Several factors must be addressed to maintain a consistent amount of dissolved ozone, including:
- Contact time between the ozone gas and the water
- Pressure exerted upon the ozone gas as it comes in contact with the water
- Thorough mixing of the ozone and the water
- Water temperature
- Bubble size and concentration of ozone inside the gas bubbles
Because water conditions tend to vary with location, an understanding of each factor’s interaction with the others is imperative in formulating an approach that maximizes the efficiency of the system / location relationship. Therefore we use a proprietary formula in calculating the ratio of variables to apply for each installation to assure quality and reliability.
Choose the Right Ozone Technology
Once you have made the decision to investigate ozone for your application, you should become familiar with the technology used to generate the gas. Several different processes for generating ozone are available on the market today — each system approaches the process differently.
The key thing to remember when specifying a system is that for the ozone to work, it must be dissolved in the water. Only ozone thoroughly dissolved in water is capable of oxidizing contaminates (dirt, oils, odors, bacteria, viruses, etc.) found on the submerged fabrics. The higher the concentration of dissolved ozone in the water, the better it is able to clean the fabrics thoroughly and completely.
Reservoir Supply Tank and Superior Mass Transfer Technology: Recommended
To consistently and reliably deliver a superior finished product with an ozone laundry system, all of the factors outlined above and others we prefer not to reveal here must be carefully addressed in the construction and installation of each system.
Successful ozone laundry systems are completely ‘non-invasive’ to your washing equipment. You want creation, mixing, storage and delivery of dissolved ozone to occur independently of your washers. Our patented reservoir system described here has many advantages including keeping the ozone mixing process independent of existing equipment. Variables such as age and condition or variations of makes and models of your existing washing equipment (and their various components, such as water pumps) do not affect the delivery of proper ozone concentrations to the wash wheel.
It is imperative to use a mass transfer (ozone dissolving) technology that has been designed to address each factor of proper and efficient transfer of gaseous ozone to a fluid state. Our proprietary method employs patented contact columns that insure all factors are addressed: bubble size, ozone concentration, proper mixing, contact time, temperature, pressure and timely recirculation through the column. Ozone lasts for only a short while after it has been created in an ozone generator. Therefore you must continuously reinforce dissolved ozone concentrations or levels will drop below a minimum acceptable level to achieve a superior finished product. This irrefutable fact requires that a reservoir supply tank is also part of a successful ozone laundry system. The reservoir tank is used to continuously circulate available water through the contact columns while awaiting delivery to individual washers. This assures the desired level of ozone concentration will always be supplied to washers. The reservoir tank also assures that makeup water coming into the system will not dilute ozone concentrations below minimum acceptable levels. We have found that levels of 2.5 to 3.5ppm of dissolved ozone are fundamental in achieving the results everyone strives to obtain. Your reservoir tank should be large enough to store a volume of ozonated water capable of handling the demand from all associated washers connected to the ozone laundry system.
An integrated dissolved ozone sensor is also required in a successful ozone laundry system. This piece of equipment constantly monitors the concentration of dissolved ozone in the water and sends exacting data to the computer controls which make decisions on how the system operates. This precise data allows the system to correctly decide when to circulate the water in the reservoir back through the contact columns in order to maintain the prescribed levels of dissolved ozone. The sensor gives operators extremely accurate information about dissolved ozone concentrations available to the washing machines.
ORP Meter vs. Dissolved Ozone Sensor: A dissolved ozone sensor is infinitely preferable to an ‘ORP’ (oxidation/reduction potential) meter. A dissolved ozone sensor gives EXACT values of dissolved ozone whereas an ORP meter gives a consolidated reading of the oxidative properties of elements present in water. The values from an ORP meter may be a combination or Chlorine, Bromine, Ozone and other oxidizing factors within the water. You are not assured that your reading is the result of available dissolved ozone. These meters also only give a reading of 1.0 or lower. If your ozone concentration is above 1ppm, you will never be able to show this with a traditional ORP meter. Our systems deliver concentrations of 2.5ppm and up.
All Water Energy systems use this advanced approach to deliver a superior finished ozone laundry product. Our design was developed by a team of chemists, chemical engineers, environmental engineers, mechanical engineers and biologists who collectively hold over 30 patents. We recommend this technology to everyone looking at ozone laundry.
Bubbling Technology: Not Recommended
Bubbling technology is the simplest method for adding ozone to water. Ozone gas is simply injected directly into the washer drum. However, with this method there is no precise way to control the amount of dissolved ozone in the wash mix. There is also no way to measure the concentration of dissolved ozone.
Several factors work against this approach. In the bubbling method, the wash drum is first filled with water, then ozone gas is pumped directly into the wash drum during the cleaning cycle. This approach does not provide enough contact time for the ozone to dissolve — the contact time is limited to the time it takes the bubble of ozone to travel from the bottom of the drum to the top.
Another problem is that since the wash drum is not pressurized, there is no effective tool to mix the water and ozone gas together. Some minute quantities of gas will be dissolved in the water where contact is made through agitation of the washer, however most of the ozone gas will be wasted without cleaning the laundry.
Therefore, we recommend customers avoid using a bubbling technology.
Side-Arm Injection: Not Recommended
Side-arm injection systems employ an eductor (or injector) to pull ozone gases into the delivery stream of water being continuously circulated to and from the washer drums. Even though this is a step up from bubbling ozone into the washer, it presents other problems.
First, the contact time of the water and the ozone gas is inadequate because of the short amount of time the water travels in the loop. If enough time is not given for the ozone to dissolve into the water, it will simply gas out into the surrounding environment.
Second, it is difficult to estimate how much pressure will be present to aid in dissolving the ozone into the water while the water is traveling through the loop, as this varies widely depending upon the size of the water recirculation pump.
Also in this scenario there is no process at work to properly mix the two elements after they are introduced to each other to make sure that the water and gas are not traveling through the loop in two separate streams.
Because of the limited contact time, mixing inefficiency, and the possible absence of sufficient pressure, the dissolved ozone levels are not consistent. Therefore, we do not recommend the side-arm injection approach for our customers.
Direct Injection: Not Recommended
Direct injection is similar to the closed-loop side-arm injection system in that it simply injects ozone gas through a venturi into washer water. Where these two methods differ is that direct injection places the injection point of the ozone gas on the supply line of the washer.
This means that a venturi is installed on the city water supply line to the washer. The venturi feeds ozone gas through the supply line which in turn goes into to the washer drum.
This approach suffers from the same performance shortfalls as Side-Arm Injection. Even though this system can utilize the pressure provided from the city water source, the actual levels of ozone dissolved into the water are extremely low due to the lack of adequate contact time. Any chemicals present in the city water, such as residual chlorine, will also act to deplete the ozone levels further.
These factors, in conjunction with the absence of a mechanism to promote mixing of the water and ozone after passing the venturi, add up to lower concentration levels and less cleaning efficiency. Therefore we do not recommend the Direct Injection approach for our customers.
About Water Energy
Water Energy was established in 1996 to promote the conservation of scarce natural resources. We deliver practical solutions to solve today's problems, utilizing the latest high technology solutions in the fields of physics, chemistry and bio-technology. We offer products and services, as well as education designed to help industry improve the environment while saving money in the process. Our ozone water treatment systems can help businesses, such as restaurants, hotels, and hospitals save tremendous amounts of money by eliminating the need for hot water when washing laundry and linens.
We invite you to join us and be part of the Water Energy revolution. Welcome aboard.
