Aquazone Ozone Systems

Introduction

Since the early 1900s, ozone has been widely used for water treatment, including disinfection of municipal water supplies, swimming pools, spas, cooling towers, and sewage treatment plants. Increasingly now ozone is been used in food processing for sanitizing raw materials and irrigation waters, sanitizing packaging materials and storage facilities, sanitizing water for recycling and process water.

Prior to 1997, ozone could only be used for sanitation and purification of bottled drinking water in the U.S., and it is widely used around the world for this purpose today. In May 1997, an expert panel assembled by the Electric Power Research Institute (EPRI) declared ozone to be Generally Recognized as Safe (GRAS) for use in food processing in the U.S.

Since then, bottling plant operations, wineries and breweries have embraced the use of ozone. Its use has been generally accepted and documented to be effective for barrel cleaning and sanitation, tank cleaning and sanitation, clean-in-place systems, and for general surface sanitation.

This same trend of acceptance has been noted in many other industries, such as fresh-cut produce processing; produce storage facilities; food processing, including meat processing facilities; and, as noted above, in the bottled water and beverage industries. In these industries, the ozone systems are generally permanently mounted or fixed in place, which makes management of off-gas and ozone monitoring for safety and efficacy relatively easy.

Drinking Water

Ozone has long been recognized as an effective method of treating drinking water to improve taste and safety for municipalities, small communities and residences.

In comparison ozone does not have any chlorinated compounds or other unpleasant by-products, odours or flavours and does in fact eliminate any carcinogenic compounds and also the tastes and odours indigenous to a particular body of water.

Chlorine is currently being replaced in water treatment plants with ozone in the pre and mid treatment phases. Various tests have been carried out for a number of years in order to estimate the reactive power of chlorine and ozone in the destruction of bacteria and viruses. It has been clearly demonstrated that ozone is much more efficient than chlorine as a disinfectant.

Perhaps the clearest example of the superiority of ozone against chlorine is that given to us by R N Kinman using distilled water with a pH of 7 at 25 degrees in which there was a 106/mg of E.Coli; .01 mg/l of ozone was enough to destroy all the micro-organisms in fifteen seconds, while an amount similar to this using chlorine is ineffective and an amount sixty times this with double the time is needed to disinfect the water.

Therefore, ozone disinfects 600 to 3000 times faster than chlorine.

Wastewater

Ozone is presently used in the treatment of industrialized wastewater processes. It is commonly used for the following processes:

• Algae removal
• Bacterial disinfection
• Color removal
• Decomplexing organically bound manganese
• Increase biodegradability of dissolved organics
• Odour control
• Oxidation of soluble iron and/or manganese
• Preparation of granular activated carbon for biological removal of ammonia and dissolved organics
• Destruction of Cyanides
• Destruction of organics
• Suspended solids breakdown
• Viral inactivation

Ozonated water as a detergent or sanitiser

Even though ozone is the second most effective oxidiser known, it has no harmful derivatives and has a non-obnoxious odour. The short half life properties of ozone are a disadvantage where residual protection is required such as in storage reservoirs or pipe reticulation systems but are an advantage where there are no residual harmful chemicals left behind, such as with chlorine, and the ozone works faster and is stronger than chlorine.

Ozone Versus Chlorine

The concentrations of disinfectants, in mg/l needed to kill or inactivate 99% of the organisms are tabulated below after ten minutes at 5ºC.

Ozone as a detergent rinse

Ozone is effective in destroying surface-attached bacteria, even at high cell densities and in the presence of high organic material. Ozone requires no heat and, consequently, uses less energy than sanitizing systems that use steam or hot water. Costs of chemical sanitizers would be reduced or possibly eliminated by use of ozone as a sanitizing agent. Furthermore, release of chlorinated chemical residues to the environment would be reduced.

Rinsing of fresh food

Packaging plants have used ozone in the USA since the mid 90's to improve the quality of the fruit and vegetables shipped to customers and at the same time reduce the use of water and the amount of BOD discharged to treatment works.

To get away from chlorine use and to extend the use of the water, ozone treatment systems in the flume water can be used. For the flume water gaseous ozone is injected into a side stream after filtration. The ozone is generated in corona discharge unit, which is fed with dried air. After about 10 minutes of exposure to the ozonated water, the product is conveyed to a size grader and inspection belt.

To ensure that the maximum amount of ozone in the air does not exceed the OSHA limit of 0.08 to 0.1 ppm, an ozone detection unit can be used to continuously monitor the amount of ozone in the environment adjacent to the flume.

With this treatment flume water does not have to be replaced daily. The plant can reuse the same water for a whole week resulting in considerable savings in water costs.

The ozonation system can be run for 24 hours a day which will enable reduction of the BOD load in the flume water, particularly during the night when the products are not being washed. The ozone treatment will reduce the yeast and mould count in the water, resulting in cleaner product and a longer shelf life.

An example is the fresh market carrot industry which use large amounts of water for washing, transporting and cooling and for which the historic technology for microbial control has been chlorination. Chlorine treatment is now banned because of the chlorination by- products formation and their potential toxicity. This has created the need for more environmentally friendly water sanitizing approaches. The application of ozonation can be used as a sanitizing method for micro-organisms in process waters.

Bottled water treatment

In the early 1980s, the International Bottled Water Association petitioned the FDA to affirm that the application of ozone to disinfect bottled water under specified conditions is GRAS. The conditions included a maximum dosage of ozone of 0.4 mg/L over 4 minutes contact time, and that the water to be treated must meet the potable water requirements of the U.S. Environmental Protecting Agency. The FDA approved the application for bottled water, and in 1982 published in the Code of Federal Regulations a formal FDA regulation affirming GRAS Status for use of ozone (FDA, 1982). Later, the FDA also approved the use of ozone as a sanitizing agent for bottled water treatment lines, under a similar GRAS petition.

The 1997 EPRI GRAS Declaration
In June 1997, an Expert Panel of Food Scientists convened by the EPRI (EPRI, 1997) concluded the following:
“The available information supports the safety of ozone when used as a food disinfectant or sanitizer, and further, that the available information supports a GRAS classification of ozone as a disinfectant or sanitizer for foods when used at levels and by methods of application consistent with good manufacturing practices.

Ozone treatment is the most frequently used disinfection process in water bottling today. With the application of a single ozone treatment step, the water bottler can disinfect the water, the bottling equipment, the bottle, the air above the water and the sealed cap of the bottle, thereby provide a most effective barrier to microbiological contamination for the protection and benefit of the consumer. These are the reasons why most water bottlers rely on ozone treatment to provide a safe, good tasting, aesthetically pleasing and storage stable product. As the ozone treatment became a well accepted, routine part of the water bottling process, many of its other benefits beyond the disinfection have become taken for granted and nearly forgotten. Some water bottlers may not even realize today that the use of ozone also provides benefits, such as, improved taste, elimination of odour, and long 2 years storage stability. These benefits have improved their product substantially making it a good tasting and safe. These are the product quality features that the costumers have grown to expect and enjoy.

Because it’s highly reactive and unstable, ozone doesn’t persist—any ozone not instantly consumed by contact oxidation of organics quickly reverts to oxygen. This makes ozone perfect as a final, no-rinse sanitizer. With no persistence, ozone requires no special disposal system. Ozonated water going down cellar drains won’t kill the bugs in your biomass, pollute your pond or destroy beneficial bacteria in your septic system or wastewater treatment plant.

Ozone is just as reactive when dissolved in water, where it is pH neutral and non-corrosive. Ozone reacts with dissolved iron and manganese, precipitating those ions for easy removal. And compared to hot water or steam, its chief rival sanitizers in wineries, ozone is dramatically less expensive to produce and safer to use. Switching to ozone sanitation can cut a winery’s hot water usage in half.

Ozone won’t harm stainless steel, most plastics or fitting and sealant materials like viton, silicone, Teflon, kinar, and epdm. Handled correctly, ozone can be safer than SO2 or steam. There are no storage, handling or reporting requirements for ozone. Ozone can also maintain and improve the microbial health of oak barrels. All in all, ozone offers a number of benefits to wineries as a fast, effective, environmentally friendly sanitizer, with no residue and no residual.

Ozone Surface Sanitation

Many wineries sanitize surfaces with ozonated water. It can be sprayed directly on floors, drains, walls, destemmer-crushers, tanks (inside and outside), fruit bins and any other wet- table, non-rubber, non-fiberglass equipment or surface in a winery. Typically, the equipment is first cleaned, then ozonated water is used as a final sanitizing rinse. This very effectively reduces microbial loads on the surfaces.

With repeated use, surface applications of ozonated water will remove biofilms. These are tough, resilient layers of microbes which adhere tenaciously to surfaces. Biofilms can be invisible or they can create a foggy haze on tank walls and cellar floors. First-time users of ozone sometimes measure post-treatment surface bacteria counts higher than pre-treatment counts. This is due to the destruction of the upper part of the biofilm by the initial ozone treatment, exposing the microbes below. Subsequent treatments quickly destroy those microbes, leaving the surface microbiologically sanitized as well as clean to sight and touch.

CIP (Clean In Place solutions)

Wineries have all kinds of equipment which cannot be taken apart to be cleaned. To sterilize these tanks, runs of pipe, hoses, bottling lines, fillers, etc., they must be cleaned in place (CIP). First, the CIP equipment is cleaned with soap and/or surfactants and thoroughly rinsed. For the sanitizing step, ozonated water is recirculated through the equipment using a closed loop of pipe or hose. The circulated ozone reacts with organic material in the CIP equipment. When there are no organics left to destroy, dissolved ozone will be detectable in water leaving the equipment. To ensure that sterility has been achieved, ozonated water is left to recirculate a few additional minutes after the effluent concentration of ozone matches the output of the generator.

Without ozone, CIP sanitation must be done either by chemicals (usually chlorine or iodaphore solutions), requiring multiple rinses afterwards to remove noxious residues, or by heat (usually high-temperature water or steam), which is very expensive to produce and creates a danger for cellar workers. In contrast, ozone achieves CIP sanitation at low cost, at ambient cellar temperatures, and without chemical residues. Further, hot water or steam causes the expansion and contraction of welds, one of the biggest causes of line degradation and repair. Heat also can bake on materials inside the lines, making them more difficult to clean. Since ozone is used in cold water, it avoids these and other problems of heat-based CIP sanitation.

ULTRA VIOLET TECHNOLOGY

Ultra Violet rays achieve disinfection with complete elimination of viruses when the rays are applied to a thin layer of water. The lamps must be strong enough and may require renewing before there is a notable decrease in the UV radiation output. The water should be transparent, without cloudiness or colour, iron free and clear of organic colloids or plank tonic micro organisms. Water contaminated in this way will lead to sediments being formed on the tubes reducing the penetration of the rays.

If the above steps are applied to all living cells, in active or spore form, they will be destroyed or at least be unable to reproduce.

Comprehensive treatment is only obtained with an installation with wide dimensions, which are properly controlled and maintained and used with water, which has a consistent quality. Difficulties will be encountered in treating large volumes of water.

UV irradiation systems disinfect by inactivating pathogenic micro- organisms, such as viruses, bacteria’s and parasites. In the UV-C light spectrum (200-280 nm), the wavelength 254 nm has been proven to be the most efficient wavelength to inactivate micro-organisms by damaging the nucleic acids (DNA and RNA), which disrupts the organism’s ability to replicate.

The normal applications, UV has the advantage that no chemicals are added to the process and that no disinfection by-product are formed. Owing to the small footprint, the UV equipment can be easily integrated in to most existing installations