Ultraviolet (UV) light is a potent technology that has been successfully deployed for decades in many diverse industries ranging from pharmaceutical, food & beverage, cosmetics, health care, aquaculture etc. Today, we will focus on the applications and benefits of UV technology to the food and beverage industry for the production of high purity water. Properly designed UV systems can be used for various applications such as disinfection of water, surface disinfection, ozone destruction and chlorine destruction.
The fundamental UV wavelength used for water treatment is 254 nm (= 2540 Å). UV light at this wavelength has the unique ability to destroy microorganisms and therefore can be effectively used for disinfection. It works by penetrating the outer cell-wall of the microorganism and altering the genetic material (DNA) thereby killing it. At higher doses, this same UV radiation can be used for chlorine and ozone destruction.
The use of UV technology for water treatment has many advantages. UV radiation does not add anything to the water (such as unwanted color, odor, chemicals, taste), nor does it generate harmful byproducts. At the same time it is fast, effective, and efficient. In the case of disinfection of fresh produce, UV will leave no residue as compared to chlorine or irradiation treatment with gamma rays.
Where can UV be used?
Disinfection of water used in process
As already established, UV is an effective method for achieving reduction of microbial contaminants from water. The degree of reduction is dependant on the applied UV dosage (measured in uW-sec/cm2). For most typical applications, UV systems can achieve microbe inactivation rates up to 99.99% with a dose of 30,000 uW-sec/cm2, rendering your water safe and clean in a reliable and cost-effective manner.
Disinfection is the most common application of UV radiation in water treatment. There are several locations within a food / beverage water system where UV equipment could be installed for disinfection. The typical locations are post-carbon filter, pre / post-storage tank, pre-RO, within the polishing loop, etc.
In recent times, the use of a UV system just before the RO has become very popular as this greatly reduces the bio-film build up on the membrane resulting in increased membrane life of more then 50%.
Liquid Sweetener Disinfection
Concentrated syrups have a high osmotic pressure which prevents micro-organisms growing and reproducing. However they will survive in spore form and grow once the syrup is diluted into the food product or beverage. This microbial growth can cause food discoloration, affect the flavors, and shorten shelf life.
For the beverage industry in particular, the disinfection of liquid sweetener is very crucial. Since the UV transmission characteristic of such liquids is very low, specially designed UV systems are required for treating such streams. These systems use high output UV lamps which are packed much closer together to ensure proper UV dose distribution.
Chlorine Destruction
UV radiation has successfully been proven to destroy residual chlorine present in water. It has been found that up to 1.0 ppm of chlorine can be completely destroyed by using high doses of UV. The exact UV dosage will depend on the chlorine concentration and the feed water quality.
Conventionally, either activated carbon beds or chemicals such as sodium meta-bisulfite have been used to remove the residual chlorine. However, such methods have drawbacks. For instance, the activated carbon beds act as a hotbed for bacterial growth and can cause serious microbial problems downstream. Further, there is a significant running cost involved with recharging/replacing these beds. UV on the other hand can be used to destroy the chlorine and eliminate the need for chemical handling, bacteria problems, etc.
Ozone Destruction
Ozone is a commonly used as an in-line sanitizing agent in the Beverage Industry. It ensures that the storage tanks, piping, pumps, valves, etc. remain bacteria free. However, this residual ozone needs to be completely destroyed before this water can be used in the end product. In such cases, UV technology is the proven method of choice as it is an instant reaction and does not involve using any chemicals.
Again, it is important that the UV system be well designed as a very high UV dose is required. The size of the UV system required depends on the operating flowrate, ozone concentration, quality of feed water and the temperature of the stream. In general, a UV dose of 90,000 uWs/cm2 is required to destroy 1.0 ppm of residual ozone.
Surface Disinfection
From disinfection of water, we now talk about surface disinfection of meat, fish, poultry, fruits and vegetables. Let’s take the case of fresh fruits and vegetables that are cleaned, packed and sold by importers and packagers for supermarket chains. The objective here would be to destroy microbial contaminants such as bacteria and fungi that occur naturally on fruits and vegetables and which are responsible for premature spoiling. In such a case, UV disinfection systems can play an important role in destroying surface contamination and extending the shelf life of the raw produce. Only a few seconds of exposure can achieve up to 99.999% destruction of common microbiological contaminants which are problematic in the food industry. This predetermined time and dosage will be adjusted to sterilize the pathogens depending on the nature of the produce.
Conclusion
Based on the above, you will agree that UV is a very useful, effective and reliable tool for the food and beverage industry. It can be used for purposes such as disinfection, ozone destruction and chlorine destruction. However it is a specialized subject requiring specialists to handle it and get the maximum mileage from it.
One important point to remember with UV systems is that they are effective and reliable only when carefully sized, maintained and monitored. The company supplying the UV systems should have in-house expertise in design, engineering, supply, installation, and commissioning of the unit. They should also be able to provide dependable after sales service and be able to troubleshoot at sight. Further, it is very important that the systems be validated because without this, there is no way to prove that the given UV system is able to meet disinfection requirements under a variety of conditions.
