Over the last decade there has been an increased demand for water in bottles, cans, etc. This demand, or trend, has drawn manufacturers’ attention to the need for specialized filling techniques, proper sanitation practices and water disinfection or sterilization, typically by ozonation and occasionally with ultraviolet (UV) light. For maximum flexibility and ease of implementation, complete skid mounted ozone systems for large or small bottling plants are readily available.
Beverage filling plants can be complex, often made up of a variety of unit processes including, but not limited to, influent treatment, product water make-up, syrup/concentrate addition, carbonization, bottle washing, bottle filling, PET blow molding, crating, storage, distribution and more.
Because of the relatively large investment involved, operators are compelled to arrange their facilities so they can fill as many different beverage products as possible. Operators must make the most of the bottling equipment, as well as comply with stringent regulations.
Cleanliness is an important factor to enhance product quality. Most bottling companies rely on the use of ozone to meet the ever-increasing legislative and consumer demands.
There are three reasons to use ozone when bottling drinking water:
- Ozonation of the wash water used to clean the bottles prior to filling;
- Ozonation of the actual bottling water;
- Ozone for Clean In Place (CIP) system sanitation
It is obvious that the purpose of washing is to clean the bottles before filling. There are two basic types of bottles used extensively today:
- PET type bottles, which are freshly blown immediately prior to filling. Although these bottles are new, operators must subject the bottles to washing in order to remove any possible mechanical debris.
- Reusable glass bottles, which need to be intensively cleaned so that all debris and any possible residues from the filling are completely removed.
Typically, the washing process for these bottles involves the insertion of a nozzle into the inverted bottle through which a high pressure jet of water thoroughly cleans the inside surface of the bottle of all mechanical debris, deposits, etc. In addition to the mechanical cleaning, filling companies require that this cleaning also disinfects the bottles in order to avoid microbial contamination after the filling and capping of the product.
As with all ozone applications, special measures must be taken to prevent unacceptable levels of ozone build-up in the ambient surroundings.
Experience has indicated that a small dose of ozone from a high concentration ozone generator in the region of 0.3 mg/l to 0.5 mg/l is sufficient to sanitize the product and the product packaging. After filling the ozonated product, the crated or palleted bottles are placed on stock for several days to allow the ozone to decompose.
After this period, the ozone will have oxidized the organic substances in the product water; the microbial activity will have been reduced to a minimum (or even) sterility; and the remaining unreacted ozone will have decayed to form diatomic oxygen.
There are several ways to introduce the ozone to the water, each of which has its own merits depending on the type of filling plant.
This method has shown excellent results and is particularly suited to smaller applications with fewer plant components. Attention must be given to the fact that the ozone mass transfer takes place in a virtually pressureless chamber that allows inexpensive porous diffusers to be used.
However, it does mean that any pressure in the system before the contacting volume will be reduced and that a contact chamber (approximately 6m high) must be incorporated into the design, followed by pumping to the bottle filler.
A second alternative is ozone injection with a venturi eductor. This system requires a motive water pump, venturi gas injector (eductor) and automatic degassing valve on the contact chamber.
An advantage of this system is the fact that the high contact chamber mentioned in the previous example can be replaced by a unit only 2m to 3m high, which is of particular interest where height is limited.
Complete skid mounted ozone systems including the venturi/pump apparatus for large or small bottling plants are readily available.
Regardless of the method of ozone addition selected, the final bottled product will be dramatically improved with consumer safety and confidence increased.
Ozone gas can be injected in water in different ways. The two most used techniques are:
· Static Mixer
A venturi injects the ozone gas in the water via a vacuum. The advantages of a venturi are: the compact installation, possible high yield (up to 90%). In the picture below an example of a venturi system can be found. A side stream injection with pump is used.
A diffuser works under pressure. A diffuser creates a bubble column. The advantages are high yield, simple construction and advantagous for high flow rates (i.e drinking water systems). Disadvantages are the required surface area and the need of tall buildings to increase the efficiency