Ultra-violet systems ensure quality water

For manufacturers seeking to improve product quality of the end product, UV is an economic, realistic option widely used for high purity applications where water of the highest quality is essential.

In an increasingly regulated and safety-conscious market, the food and beverage industries have to meet ever more stringent standards of quality.

Microbial growth due to contaminated water or ingredients can cause discolouration, off flavours and shortened shelf-life.

The threat of contamination is further increased as manufacturers respond to demands for less chemical additives and preservatives.

Effective microbial disinfection of the whole process is therefore essential.

A non-chemical disinfection method which is gaining increasing acceptance is ultraviolet (UV) disinfection.

UV kills all known spoilage microorganisms, including bacteria, viruses, yeasts and moulds (and their spores).

It is a low maintenance, environmentally friendly technology which eliminates the need for chemical treatment while ensuring high levels of disinfection.

* How UV disinfection works - UV is the part of the electromagnetic spectrum between visible light and X-rays.

The specific portion of the UV spectrum between 185-400nm (known as UV-C) has a strong germicidal effect, with peak effectiveness at 265nm.

At these wavelengths UV kills microorganisms by penetrating their cell membranes and damaging the DNA, making them unable to reproduce and effectively killing them.

A typical UV disinfection system for process water or liquid ingredient consists of a UV lamp housed in a protective quartz sleeve and mounted within a cylindrical stainless steel chamber.

The liquid to be treated enters at one end and passes along the entire length of the chamber before exiting at the other end.

Virtually any liquid can be effectively treated with UV, including raw mains water, filtered process water, viscous sugar syrups, beverages and effluent.

There are two main types of UV technology, based on the type of UV lamps used: low pressure (LP) and medium pressure (MP).

LP lamps have a monochromatic UV output (limited to a single wavelength at 254nm), whereas MP lamps have a polychromatic UV output (with an output between 185-400nm).

* Benefits of UV Disinfection - UV disinfection has many advantages over alternative methods.

Unlike chemical treatment, UV does not introduce toxins or residues into process water and does not alter the chemical composition, taste, odour or pH of the fluid being disinfected.

UV treatment can be used for primary water disinfection or as a back-up for other water purification methods such as carbon filtration, reverse osmosis or pasteurisation.

As UV has no residual effect, the best position for a treatment system is immediately prior to the point of use.

This ensures incoming microbiological contaminants are destroyed and there is a minimal chance of post-treatment contamination.

* UV applications in the food and beverage industries - direct contact water - although municipal water supplies are normally free from harmful or pathogenic microorganisms, this should not be assumed.

In addition, water from private sources such as natural springs or boreholes could also be contaminated.

Any water used as an ingredient in food or beverage products, or coming in direct contact with the product, can therefore be a source of contamination.

UV disinfects this water without chemicals or pasteurisation.

It also allows the re-use of process water, saving money and improving productivity without risking the quality of the product.

* CIP (Clean-in-Place) rinse water - it is essential that the CIP final rinse water used to flush out foreign matter and disinfecting solutions is microbiologically safe.

Fully automated UV disinfection systems can be integrated with CIP rinse cycles to ensure final rinse water does not reintroduce microbiological contaminants.

Because of their mechanical strength, MP lamps are not affected by any sudden changes in the temperature of the CIP water.

* Filter disinfection - stored reverse osmosis (RO) and granular activated carbon (GAC) filtrate is often used to filter process water, but can be a breeding ground for bacteria.

UV is an effective way of disinfecting both stored RO and GAC filtered water and has been used in the process industries for many years.

* Dechlorination - GAC filters are also often used to dechlorinate process water, removing the 'off' flavours often associated with chlorine disinfection, meaning the flavour of the final product remains untainted and free from unwanted flavours or odours.

Placing UV systems ahead of GAC filters used for dechlorination improves the performance of the filters and results in longer carbon runs, so decreasing operating costs.

* Sugar syrups - sugar syrups can be a prime breeding ground for microorganisms.

Although syrups with a very high sugar content do not support microbial growth, any dormant spores may become active after the syrup has been diluted.

Treating the syrup and dilution water with UV prior to use will ensure any dormant microorganisms are deactivated.

* Tank head space disinfection - UV systems can be used to disinfect displacement air for pressuring tanks or pipelines holding perishable fluids.

Storage tanks are particularly susceptible to bacterial colonisation and contamination by air-borne spores.

To prevent this, immersible UV treatment systems have been designed to fit in the tank head air space and disinfect the air present.

* Waste water - effluent from beverage manufacturing facilities can be treated without the use of environmentally hazardous chemicals.

This ensures all discharges meet with local environmental regulations.

As already mentioned, because process water can be treated and re-used with UV, this also leads to a significant reduction in the amount of waste water produced.

* Conclusion - meeting the increasingly rigorous hygiene standards required in the production of food and beverage products is a real challenge.

If improvements need to be made to plant and equipment, they need to bring quick returns on the investment and measurable improvements in product quality.

For manufacturers seeking to improve the quality of the end product, UV is an economic, realistic option.

It is an established method of disinfecting drinking water throughout the world, and is also widely used for high purity applications such as pharmaceutical processing and microchip manufacturing, where water of the highest quality is essential.

UV disinfection systems are easy to install, with minimum disruption to the plant.

They need very little maintenance, the only requirement being replacement of the UV lamps every 9-12 months, depending on use.

This is a simple operation that takes only a few minutes and can be carried out by general maintenance staff.

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