A very small portion of the water on the surface of the earth is classed as fresh and usable for consumption by people and livestock. This same water is also used for our food processing plants, recreational facilities, agricultural production and a host of other uses. In the past it was customary to locate a processing plant on the edge of a river or stream with the water being used for all for all processes. If the water was not really satisfactory, it was purified and used. After suing the water, it was discharged back into the river or stream and used by the next person downstream. If the water was used for cooling there was usually very little effect on the stream. If the water was used for washing very dirty products or rinsing processing chemicals such as lye from processed vegetables, the water going back to the river or stream often
became very polluted.
Today there are laws in effect that basically state that discharge water into a stream cannot be of lower quality that the water in the stream. In many cases, discharge water must be of higher quality that the stream it flows into. These rulings, public disgust and the desire of many corporations to be good corporate citizens have led to research for technologies that can purify water without further polluting the environment. Common Oxidation and heat technologies are common technologies that can provide this purification. The heat technologies consist of evaporation, freeze concentration and freeze drying. Oxidation technologies consist of ozone, UV (ultraviolet light), and advanced oxidation. Today all of these technologies are used to treat water either before using it or to treat water so that it can be recycled and used again. The use of these technologies not only saves the environment by also fit well into business models through cost savings for water plus reduced wastewater treatment fees.
The use of evaporation and condensation are very old technologies that can be used to provide very pure water. Depending on the heat source for evaporation this technology is dependable by expensive. A much less costly technology is freeze concentration. Under the proper temperatures, ice crystals will grow and can be removed from water solutions. These crystals are pure water and the process is much less expensive than evaporation. Many of the modern desalination plants that supply water to cities in the Middle East use freeze concentration for salt removal. Freeze drying is a process where water is removed from product surfaces by going directly from gaseous phase to a solid. Hydrogen and oxygen go directly from the gaseous phase to ice. This process is used in food processing by is not usually employed to purify water.
The major oxidation technologies consist of treating water with ozone and UV light. Advanced oxidation technologies are becoming common and are being used extensively in Europe. Ozone or triatomic oxygen (O 3 ) can be formed by UV light, electrolysis, or more commonly by corona discharge (the reaction of passing diatomic oxygen (O 2 ) through an electrical discharge). This last reaction is the same event that happens in nature during a lightning storm. When ozone is formed it is quite unstable and quickly returns to O 2 . The energy released when ozone returns to oxygen is capable of oxidizing organic components. This oxidation removes the organic compounds from water and is capable of oxidizing microorganisms. Thus, a simple ozone treatment of wash water can purify the water and allow for reuse several times. This simple purification technique is now being used in food processing, laundries and other processes that use water for washing. Once the wash water is ready for disposal it can be land irrigated or placed in a wastewater treatment facility. The environmental impact of the ozone treatment is negligible as excess ozone has long returned to oxygen and the waste water contains only materials that connote be readily oxidized.
UV light can also be utilized as an antimicrobial agent that can be used as a water purification technology. Like ozone, the environmental impact of the UV is again negligible as it is dissipates quickly.
Advanced oxidation technologies are the newest of the low environmental impact technologies used in food processing. Although very complicated, the reaction of this technology consists of free hydroxyl radicals reacting to reduce microbial activity. Watch for the incorporation of this technology in future food safety techniques.
Not only are ozone, UV light and advanced oxidation exciting technologies, they are
technologies that can be used together to give provide even more antimicrobial protection in food safety. In the future we will embrace these technologies as very safe and environmental friendly methods of conserving our water sources and enhancing the safety of our food processes.
