Deaerated Water (DAW) in Breweries – Uses and Contamination Prevention
Deaerated water systems are an important component within the brewing process. Common applications include mash water, dilution water and chase water. In these critical applications, it’s important to ensure that all of the dissolved gases in the water source are removed. If the dissolved gases are not removed, off flavours can develop, beer haze forms and shelf life can suffer. In addition, unremoved dissolved gases that are present in boilers will contribute to fouling such as corrosion and pipe degradation. For DAW systems in brewery applications, dissolved oxygen levels should be <0.02ppm and <0.01ppm for boiler applications.
Once these dissolved gases are removed, the resulting deaerated water is highly susceptible to microbial contamination and spoilage. It’s critical than any DAW system includes a microbial treatment technique such as pasteurization or UV to mitigate this risk. UV tends to be the preferred technology over pasteurization due to footprint, reduced energy usage, lower capital cost, and on-demand treatment through the use of an inline UV treatment system. The two technologies attack organisms in different ways (thermal treatment via pasteurization and irradiation via UV). If thermophillic organisms are expected to be in the source water, UV may be the better solution since thermophiles could survive the heat treatment and pasteurization process.
When selecting a UV system for this application, it’s important to work with an organization that has experience with DAW systems. Understanding the UV dose requirement and properly sizing the UV system for this critical application will ensure that the microbial risk of contamination is alleviated.
More information on DAW systems can be found on the Master Brewers Association of Americas conference site. John Kyle Dorton from Alfa Laval put together an excellent presentation for the 2013 conference which can be accessed at the link below: