Improving F&B Production Safety With UV Water Treatment
Thursday, December 7th, 2017
Ultraviolet (UV) disinfection technology has become an accepted alternative to chemical disinfection in the water treatment process. Hanovia’s sales and marketing director, Tim Mcdougle, explains why UV is an ideal choice for helping increase production safety across a wide range of food and beverage industry applications.
As water can often be a source for harmful microbial contamination, the correct treatment of this critical resource is essential in improving production safety in food and beverage industry applications. Bacteria problems can originate from the municipal water supply, stagnant ‘dead leg’ zones in pipework design, or water being stored for long times or at high temperatures.
To help ensure the highest safety standards, it is therefore crucial for manufacturers to implement validated and proven water treatment technology, which is properly monitored and maintained.
Ultraviolet (UV) disinfection technology has become accepted as an alternative to chemical disinfection, and its performance meets the increasingly stringent water quality demands of global food and beverage companies.
UV systems have previously been used successfully in the highly regulated municipal drinking water sector. However, they are now also regarded as an ideal choice for improving safety in food and beverage applications, and their use has become more widespread.
How Does UV Light Disinfect?
UV is a chemical-free method of disinfecting process water and sugar syrup with varying levels of bio-security. UV disinfection systems incorporate powerful lamps that emit UV radiation, which efficiently eliminates bacteria, viruses, spores and moulds. There is no need for chemical handling, dosing equipment or waste management.
The disinfection process begins with process water travelling into the system’s chamber and being exposed to UV light. The UV lamps deliver a defined amount of power that produces UV at the effective dose for the target microorganisms. Every microbe has a different sensitivity level to UV light, with some needing more exposure than others. This is very much like human skin, where it takes different lengths of exposure to the sun for different individuals to become burnt.
The UV light penetrates the DNA of the microbes, destroying the bond between the adenine and thymine bases and preventing reproduction and DNA repair. This process takes only seconds and is very effective, but the length of the chamber and the power of the lamps are important design factors in achieving the required results.
Depending on the application and the required power usage, systems can be supplied with either low-pressure or medium-pressure lamps. Low-pressure lamps use less power and emit a monochromatic wavelength of 254 nm, which is effective against microbes that are sensitive to this wavelength of light. Medium-pressure lamps emit roughly ten times more energy, with a polychromatic wavelength output of 200-400 nm.
Although medium-pressure UV consumes more power, it is more effective against stubborn microbes travelling at high flow rates. A single medium-pressure UV lamp system has the same effectiveness as a multi-lamp low-pressure system.
How Does UV Light Stack Up Against More Traditional Methods?
For over a century, chlorine has been the most common disinfectant for water processes. It is easy to produce, inexpensive, and aggressively disinfects most microorganisms. The most common use for chlorine is as a residual disinfectant in the municipal water industry, to maintain hygienic conditions within the public water supply piping network feeding both domestic and industrial consumers.
Many industrial users also dose chlorine within their manufacturing processes, either to secure the water supply or as a Clean-in-Place (CIP) chemical for process equipment.
Producing water suitable for use within manufacturing processes requires a multitude of treatment technologies to be applied to ensure that specific water conditions are maintained. The use of reverse osmosis (RO) as the primary treatment technology is common practice and offers the user an effective treatment for most water impurities.
Where inorganic quality needs to be of the highest standard, RO is combined with electro-deionisation (EDI) to guarantee sub-ppm (parts per million) levels of salts as measured by the resistivity of the water.
While RO and EDI are stable technologies which require minimal maintenance compared to traditional cation/anion ion-exchange beds, they do need protection from oxidising species which will affect both performance and lifespan. For this reason, the removal of free chlorine prior to RO and EDI is crucial.
There have been two traditional methods for eliminating chlorine prior to RO and EDI: Activated Carbon Filtration (ACF) and Sodium Meta-Bisulphite (SMB) dosing. Both methods are well proven but, while offering secure chlorine removal, they also have certain limitations.
ACF provides a breeding ground for bacteria and requires regular heat or chemical sanitisation to maintain microbial control. It also requires media replacement, incurring significant cost. SMB requires regular chemical handling, and both ACF and SMB have a significant footprint, occupying valuable factory space.
UV systems provide a range of benefits which make them an attractive alternative to ACF and SMB. They not only provide the breakdown of residual chlorine but also deliver disinfection of the process water, resulting in minimal pretreatment bio-fouling. They have a small footprint, and because UV technology is non-chemical, it does not affect the final product in terms of taste or colour.
The following table outlines the key benefits UV systems can provide for food and beverage manufacturers, compared to ACF and SMB:
How Can I Be Assured The System Is Fit For Purpose?
Reputable manufacturers of UV technology can guarantee absolute bio-security by offering systems that have been performance-validated by an independent third-party institution. This process involves laboratory-based target bacteria UV dose responses being replicated in field-based system tests to calculate a validated performance envelope, checked and verified by an independent expert.
Although this is an expensive process, such validation reassures customers that their system will perform as required, and guarantees post-UV water quality that will ensure product safety.
Furthermore, the latest UV systems offer an online UV dosage reading, so that users can continuously monitor their performance. This reading can be logged regularly on a user’s building management system to offer traceability of water quality.
What Are The Key Features Of A UV System?
A typical UV system consists of the following key elements:
- UV lamp inside quartz sleeve: the UV lamp is protected by the quartz sleeve from any solids in the process water.
- UV intensity sensor: this instrument measures the intensity of UV light passing through the water. This is then used to calculate how much dose is being delivered.
- Auto-wiper: like a wiper on a car that cleans its windscreen to enable better visibility, the auto-wiper cleans the quartz so that UV light is not being blocked. This can be done without having to interrupt the treatment process.
- Cabinet and control: this provides the user with information on the performance of the UV system, and controls power to the system.
Routine maintenance is essential for optimum performance and can be carried out by a trained service engineer. UV lamps do wear out over time, dependant on starts and stops, and general use. A low-pressure lamp will give you around 12,000 to 16,000 hours, and a medium-pressure lamp around 4,000 to 8,000 hours.
The quartz sleeve that covers the lamp slowly solarises over time. It also requires cleaning after 12 months and it is recommended that the quartz sleeve is replaced after two years. The auto wiper keeps the quartz surface clean and every 12 months the wiper ring needs to be replaced. In terms of critical sensors, the UV intensity sensor needs to be calibrated every 12 months using a certified UV source.
How Are UV Systems Sized For Applications?
UV systems are very simple to use, but they must be correctly sized for the application they are intended for. This requires understanding of the transmittance (UVT percentage) of the water quality and any target micro-organisms. Once these are known, along with the flow rate of the process water in cubic metres per hour, qualified engineers can correctly size the system.
UV systems are now providing non-chemical treatment for product waters and sugar syrups in a wide range of food and beverage industry applications. These include:
1 Bottled water: While mineral and natural spring water are bottled untreated at source, the production of bottled purified water requires stringent process control, and UV disinfection is a proven treatment for guaranteeing bio-security and protection. UV presents a low-cost and safe choice for bottled water manufacturers, and because it is chemical-free, there is no impact on product taste or colour.
2 Carbonated soft drinks: The production of soft drink relies on a good supply of clean, bacteria-free water. UV provides the ideal choice for treating process and CIP water with proven disinfection performance, without using chemicals or impacting on final product integrity. For drinks with added sugar, UV treats the liquid sugar to prevent the growth of yeasts, moulds and thermophilic bacteria which can affect final product quality and shelf-life.
UV is proven to deliver significant log reduction of all micro-organisms, and bio-security is guaranteed with third party validated UV systems which deliver confirmed doses. Final UV treatment before concentrate dilution and bottling ensures consumer protection.
3 Dairy: The dairy industry relies on water as a critical utility in the production process for all dairy products. With a focus on bio-security and reducing the use of chemicals and energy, UV is the ideal solution for guaranteed disinfection, water treatment process protection, pasteurisation equivalence and reduced CIP frequency.
Whether extracting water from a borehole or using a municipal supply, UV provides bacterial control for all water entering the dairy site, reducing the risk of contamination and protecting the final product integrity. The use of UV disinfection enables CIP frequency to be reduced, and biofilm formation in pre-treatment (softeners, filtration and activated carbon) and RO units to be minimised.
Replacing ACF with UV enables the elimination of chlorine prior to RO without increased bacterial contamination. It is also a viable treatment alternative to conventional heat pasteurisation for producing pasteurised equivalent water for Grade A milk production, providing up to 95 percent energy saving and reduced capital investment.
4 Breweries: Brewing beer relies on water as a critical utility throughout the production process, from feed water through to deaeration and final product dilution before bottling. UV is incorporated through the production process to minimise bacterial contamination, reduce the requirement for chemicals, and protect the final product quality and shelf-life.
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