Three factors-the type and age of the barrel, its microbial health, and the concentration of ozone in the treatment water-affect how long your ozone treatments should last. Higher concentrations of ozone in the treatment water will destroy a given level of microbes faster. And the larger quantities of microbes in problem barrels require longer treatments than the smaller quantities in healthy barrels. Says John McClain of McClain Ozone, "You just don't throw SO 2 at your barrels. You just don't throw ozone at them either. Determining barrel rinse times is based primarily on the concentration of ozone in the water, and the age and the degree of contamination of the barrel. The more ozone you can get into saturation in the water, the faster your rinse time. For example, at10ppm ( achieved easily by AE15MC generator),  the rinse time for healthy barrel son a 4-head barrel washer is 30seconds. At 5ppm it would be one minute.

Ozone in Wineries

Because it’s highly reactive and unstable, ozone doesn’t persist—any ozone not instantly consumed by contact oxidation of organics quickly reverts to oxygen. This makes ozone perfect as a final, no-rinse sanitizer. With no persistence, ozone requires no special disposal system. Ozonated water going down your cellar’s drains won’t kill the bugs in your biomass, pollute your pond or destroy beneficial bacteria in your septic system or wastewater treatment plant.

Ozone has other useful qualities. Ozone is just as reactive when dissolved in water, where it is pH neutral and non-corrosive. Ozone reacts with dissolved iron and manganese, precipitating those ions for easy removal. And compared to hot water or steam, its chief rival sanitizers in wineries, ozone is dramatically less expensive to produce and safer to use. Switching to ozone sanitation can cut a winery’s hot water usage in half.

There’s more. Ozone won’t harm stainless steel, most plastics or fitting and sealant materials like Teflon®, Kinar®, and EPDM. Handled correctly, ozone can be safer than SO2 or steam. There are no storage, handling or reporting requirements for ozone. And  ozone can maintain and improve the microbial health of oak barrels. All in all, ozone offers a number of benefits to wineries as a fast, effective, environmentally friendly sanitizer, with no residue and no residual.
 

Misconceptions and Concerns
But ozone isn’t without its drawbacks. And despite what some overzealous advocates have said, ozone absolutely is not the panacea, cure-all, or single solution to every problem in the winery. As we examine some potentially negative aspects of using ozone in wineries, we'll explode some myths and highlight some basic but crucial facts about ozone use.

Any wineries which have used ozone inappropriately, and have been disappointed in the results. For example, ozonated water is not a cleaner. It's a sanitizer. Ozone doesn't attack tartrates, minerals, scale, or corrosion. It's no more effective than cold water rinses for cleaning the lees, dirt, solids and crud from the surfaces of tanks, floors, barrels or anything else. Hot water is much more effective at cleaning, with added scrubbing and possibly caustics included for tough cleaning jobs. Ozonated water may be great for killing any bugs remaining on the surface after cleaning, but until the crud is gone using ozone is a waste of time and money. Sums up Joe Mendez of Piper Environmental Group, "Regardless of what anybody tries to sell, ozone is not a silver bullet. Ozone is not always the right answer, especially for cleaning. Ozone is a lousy cleaner. If you want to clean, go to Costco, buy yourself a powerwasher, and clean. Use the ozone after you've cleaned."

Similarly, ozone is not a sterilizer, just a sanitizer. Sanitizing means controlling microbial populations by dramatically reducing their numbers. Ozone will do that. But sterility is a much more difficult state to attain- complete destruction of absolutely almicrobes. In the lab, microbial kilrates are expressed in log numbers, where each log is a reduction in about 10%. A 1-log reduction kills 10% of the bugs, leaving 90% alive. A 4-log reduction kills 99.99% of the microbes, leaving 0.01% alive. (One test of ozonated water treatments indeed shows that Brettanomyces organisms are killed at the 4-log level. See chart above.)

But leaving alive only one ten-thousandth of the organisms on the surface of a barrel does not mean that the barrels completely sterile. Microbes are small and exist in large numbers. If there were a million Brett cells before the ozone treatment, a 4-log reduction means that about 100 are still alive and kicking. That isn't sterility, but it may be good enough microbial control for a working winery. We'll come back to this sterility-versus-control issue in Part 2 when we talk about treatment times for problem barrels and bottling lines. etc.