By injecting ozone (O3) into wash and rinse water, laundry gets cleaner and is completely disinfected with cold water, potentially reducing chemical use and number of cycles needed.  Ozone works best in cold water so there is less hot water required as for standard laundry applications.  The savings associated with ozone laundering include water/sewer; chemical, hot water fuel, electrical energy, and labor (due to shorter wash cycles and drier fabric emerging to the washers) resulting in reduced drying times.  There is some limited savings in chemical usage.

The system works because of the extremely high oxidation potential of ozone.  The ozone molecule is composed of three oxygen atoms that are very unstable (very reactive).  Oxygen normally prefers to be in its stable diatomic state of two oxygen atoms, so the third atom breaks away very quickly.  The half-life of ozone is usually less than 10 minutes.  Ozone is an extremely powerful oxidant that works 3,000 times faster and is 130% more effective than chlorine but without chlorine’s dangerous properties.  It is also excellent for destroying bacteria and controlling odors.  In ozone laundering there is between 99.5% to 99.7% bacterial and viral kill count.  Ozone decomposes fats, oil, and grease (FOG) in addition to purifying and disinfecting the water however, we do not include savings associated with heavy soil fabric contaminated with FOG and recommend that this type of laundry is done in high temperature and with standard chemistry.

Since ozone is so unstable and cannot be shipped or stored it must be made at the point of use.  The unit takes in ambient air to produce the ozone through a corona discharge process.  The ozone gas is transferred to the water supply through a small bubble diffuser in the base of the wash machine when the wash formula calls for ozone in the washing cycles.  The equipment is not extremely large or bulky and easily fits in a corner of a room.

Because fewer chemicals are used in the laundry process, softeners are reduced, drying times are usually shorter, and fabrics tend to last longer. Ozone often reduces the need for chlorine bleach and 140º F wash temperatures.

Ozone is much less harsh on fabric when compared with high temperature washing with chorine bleach – resulting in a significant reduction in purchases of replacement fabrics.  We have found in laundries that customers often realized an average of 25% to 40% reduction in linen costs.
In summary, the following are the savings that will be realized with an Ozone System:

• Labor.  Labor savings are not applicable to this project although there may be a slight reduction in washing time and some reduction in drying time.  In some commercial laundries this can have an impact on labor as a reduction in operational hours.  We have not included any of these potential these savings in our analysis.

• Water & Sewer.  Water savings will be realized due to a reduction in rinse water requirement.  Since fewer chemicals are needed, less water is needed to remove them from the laundry.

• Energy.  Ozone works best in cold water. Therefore, hot water is significantly reduced when compared with standard laundry practices.  In addition, energy savings are realized from reduced drying times partially due to the effects of ozone.  We have not included any reduction in drying times in our savings (approximately 12% - 15%).

• Chemicals.  Ozone will replace the need for a portion of the present chemical usage.  We have not accounted for any chemical savings in this measure (approximately 20% to 30%).

• Linen.  Ozone does not degrade linen as much as conventional chemical/high temperature washing does.  We have not accounted for any reduction in linen or uniform costs for this application although some may be realized.

Commercial laundries are an excellent place to consider recycling water used in the laundry process.  Several systems and approaches are available to achieve water and energy savings in this area.  Reusing final rinse water, approximately 20% of the water in a cycle, carries a lower initial investment cost.  A comprehensive reuse system can recycle approximately 80% of total wash/rinse cycle water.  This approach carries a large initial investment but also carries the greatest potential for long-term savings. 

The system that we recommend can recycle 75% –85% of the water for reuse and approximately 50% of the energy is also recovered.  The system does require space for holding and filtration tanks which will vary depending upon the size of the system required.  However, no other system approach will deliver the combination of water and energy savings.   

The system operation is straight forward - wastewater recovered from the “trench” is pumped into a holding tank where ozone is injected to disinfect the water.  Ozone acts as a micro-coagulant which emulsifies fats, oils and grease (FOG) and other hydrocarbons causing them to oxidize and float to the top of the tank. 

The water is then sent to a lint shaker table where the water is “screened” of lint and large solids in the process water.  Solids larger than 70 microns are removed.  Next, the water is sent to filtration tanks with 7 layers of filtration media including anthracite, garnet, gravel, sand, zeolite to trap remaining solids still in the water circuit.  Each successive bed along the path has a higher level of filtration which enables an increasing amount of filtration.  When complete, particles larger than 3 microns have been removed by this filtration method. 

Granular activated carbon (GAC) filtration is next in the sequence.  GAC removes all free fats, oils and grease (FOG) in the water as well as organic compounds, remaining hydrocarbons, surfactants, toxins, and other chemicals accumulated in the wash process.  Most chlorides and odors are removed via the GAC as well.  GAC is the single most important component in the system.
A final holding tank is then utilized to store all of the process water until it is needed for the next wash or rinse cycle.  Additional ozone can be sent to this tank for additional disinfection if required.  Ultraviolet (UV) disinfection is also utilized as the final method of disinfection to kill any remaining bacteria and viruses in the water before sending it back to the washers.  Water from the final holding tank is also used as the backwash water for the filter vessels.

Space requirements vary from 100 square feet on the smallest system to approximately 260 square feet on the largest system which can process 225 gallons per minute.  If space is at a premium, as it usually is in most laundries, only the core components such as the pumps, control panel, and UV unit need be located inside the building.  The filtration and storage tanks are made of weather resistant plastic and fiberglass and can be located outside the building if necessary.  Space requirements vary from 100 square feet on the smallest system to approximately 260 square feet on the largest system which can process 225 gallons per minute.  If space is at a premium, as it usually is in most laundries, only the core components such as the pumps, control panel, and UV unit need be located inside the building.  The filtration and storage tanks are made of weather resistant plastic and fiberglass and can be located outside the building if necessary.  Electrical requirements are 100 amps at 230 volts (or 460 volts if absolutely necessary).