UV Treatment of Water in the Food and Beverage Industries

The pharmaceutical and food & beverage industries are unique in that their products are either consumed directly or are used in products that are actively consumed by people. In an increasingly regulated and safety-conscious market, these industries have to meet ever more stringent standards on water quality and bio-security.

It is vital to treat the water used in the manufacturing process to remove toxins, biohazards and any unwanted organic materials, while at the same time not incurring any residual taste, colour or reagents that could affect another part of the downstream process. In these industries  the  ‘raw’  potable  water  they  source  at  the  start of the process may not be completely free of bio-challenges, as needed for their individual processes, resulting in active growth of microorganisms to harmful levels.

UV is ideal for these applications as it is both effective and chemical-free. It eliminates all known pathogenic and spoilage microorganisms, including bacteria, viruses, yeasts and moulds (and their spores) and is low maintenance and environmentally friendly.There are no microorganisms known to be resistant to UV; this includes pathogenic bacteria such as Listeria, Legionella and Cryptosporidium (and its spores, which are resistant to chlorination).

The importance of bio-security

Bio-security is very important to understand from both the supplier and customer perspective. It is a fine balancing act between providing an appropriately-sized treatment system on the one hand while ensuring viable cost of ownership on the other.

Where a UV system is required to target a specific bacteria, virus or other bio-hazard, the precise minimum dose needed to achieve the required reduction of that hazard must be well characterised and monitored in delivery. Three general types of system can be used for this task:

• Very cost-effective systems monitored for a minimum lamp intensity that achieve a minimum delivered dose which is not defined 
• Cost-effective systems that have been referenced to known validations and therefore offer an assured bio-security, but without the absolute cost of a full validation 
• Costly systems that have been fully validated to monitor the precise dose delivered and the power of the system controlled to continually deliver that required dose 

UV dose

The UV dose necessary for microbial deactivation varies from one species to another and is measured in millijoules per square centimetre (mJ/cm2). Values for specific microorganisms have been experimentally established and are used to determine the type and size of UV system required.

The dose received by an organism in a UV treatment system is dependent on four main factors:

1. The energy output of the UV source 
2. The flow rate of the fluid through the treatment chamber 
3. The transmission value (ability to transmit UV light) of the fluid being treated 
4. The geometry of the treatment chamber 

By optimising these criteria, a UV system can be tailored to effectively treat large or small flows, as well as viscous fluids or those containing dissolved solids and high levels of starch or sugar compounds. 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.