These waters are usually semi closed loop systems, which are essentially open to the atmosphere and readily undergo contamination. Further, through the process of spills and broken bottles/containers, they possess a significant organic load, thus creating a high potential for biological load. Slime and odour causing micro-organisms can not just survive, but can flourish in these waters. There are considerable economic, aesthetic and health reasons for keeping these waters in a sanitary condition. Except for the “hot” section of the pasteuriser, the systems that hold these waters are susceptible to biofilm build up. This effect will produce a condition called heat transfer resistance in the heat exchanger elements of these systems, resulting in wasted energy and money. In addition, biofilms will cause clogging and restriction of lines, orifices and pumps, again causing inefficiencies and wasted money on down time and repairs. In a summary report on the last two years of biofilm research, Chlorine dioxide has been listed as one of the most effective compounds for the destruction of biofilms. Our experience conforms completely with their findings. Chlorine dioxide is highly effective in removing biofilms from these systems.

Another costly factor with these waters is their ultimate discharge to the drain. The longer these waters can be retained in a sanitary condition, the more money is saved in water costs, water discharge, and energy required to heat up the replacement water. The final and best reason for sanitary water is that the consumer expects their food containers to be processed in a sanitary environment, and will not tolerate otherwise. Typically halogen based (chlorine, bromine) compounds display a high degree of corrosivity over time, in some cases relatively short times. The Chlorine dioxide chemistry is compatible with phosphate based anti-corrosion water treatment products commonly in use with these systems.

Depending on the configuration of the systems, Chlorine dioxide can be periodically batch loaded into the water system at a final concentration of 5 ppm, or can be metered in on a timed basis during the process day. In many plants this application has extended pasteuriser waters 4-6 times their previous discharge cycle and has been highly economical in overall costs associated with these systems. Chlorine dioxide holds all the necessary government approvals globally.

These water systems have been considered closed systems and therefore immune to contamination, particularly since residual chlorine or another water disinfectant is applied to these systems routinely. Weekly micro sampling of water samples often reveals quite the opposite. While most of us would consider the nutrient level in plain water not enough to support microbial growth, again, this is not the case. Published work indicates that biofilms can and do establish themselves in such water systems that trace elements and the pipe itself can support microbial growth, usually in the form of a biofilm. Once a biofilm is established within a distribution line, it can serve to seed the rest of the system. From time to time back pressures may occur within most distribution systems which can literally draw product into these water lines. This influx of nutrients can cause a population explosion of biomass, and thereby extend the area of contamination far beyond its original location. Because planktonic (free floating) cells are much easier to destroy than those rooted in a protective biofilm, a disinfection procedure often produces excellent results initially, but within 7 – 10 days the counts return. Ordinary disinfectants are unable to destroy the sessile cells of the biofilm. This is where Chlorine dioxide is the difference between a solution and a temporary fix. Chlorine dioxide is able to penetrate, disrupt and destroy the biofilm where chlorine is completely ineffective.

Disinfection of the water distributor network within a large brewery is an involved process with the most difficult factor being to identify and isolate specific runs or circuits of waterline. Each line should be walked and potential sources of continual contamination (dead legs, corroded valves, old sample ports, leaks) should be identified and corrected. This should be done in a systematic fashion, beginning at the central most location and working outward. A fairly accurate estimation of the volume of the line should be calculated, and a like volume of activated ClO2 solution at 100 – 200 ppm, depending on the severity of contamination, should be prepared. Existing water from the isolated line should be discharged and replaced with the disinfecting solution, making sure that all areas of the circuit have contact with the solution. After a minimum of one hour holding time (not to exceed 2 hours) the line should be drained, then flushed with clean potable water. Chlorine dioxide may be used as a primary water disinfectant in municipal water  and in stored potable water. If feasible, Chlorine dioxide treated water should be used to refill these lines, otherwise normally treated water may be used. Once the first circuit is disinfected and samples taken, the same procedure should be employed sequentially with the remainder of the waterlines.