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Copper Ionization Is Safe, Effective and Affordable

Despite extensive measures by the industry to ensure a food supply free of microbial contaminants, foodborne outbreaks of gastroenteritis continue to occur. The outbreaks can be linked to contaminated fresh produce, which often is consumed raw. Also, the uneven surfaces generally found on fruits and vegetables make it difficult to remove or inactivate microbial pathogens on the surface.

Water used for irrigating fruits and vegetables can become contaminated with pathogenic bacteria, viruses, or parasites. So, in addition to protecting source water, it may be necessary to inactivate microbial pathogens in water used for crop irrigation. Copper ionization is an effective way to accomplish that.

Copper ionization electronically releases positively charged copper atoms by applying a low-voltage current to copper electrodes suspended in water. Copper ions in water can pierce the protective outer membrane of cells, disrupting the enzyme balance, which leads to cell death. Proven effective for inactivation of algae, copper ionization provides a disinfectant that is not harmful to human consumers, is relatively inexpensive, requires little maintenance and is available to plants as a micro-nutrient.

Investment costs for copper ionization are less than the costs of UV, ozone or the constant use of chemicals. Copper ionization also is less expensive to run than alternatives. After the initial purchase, the only costs are power and copper replacement, which usually is necessary every one to two years. Maintenance required is minimal as well. Copper rods and/or plates should be wiped off once every six months, if needed, and the paddle wheel on the flow meter should be cleaned once every three months.

Scientific Opinions

In an article on copper ionization, Ratus Fischer, a greenhouse expert who with Lars Marohn and Aksel De Lasson coauthored a Grower Talks Magazine article on the subject, has called copper ionization “a predictable means of pathogen, algae and bio-film control.” He declared it “valuable in treating recirculated or pond water” and said tests show that free copper can reduce both bacterial and viral indicators. “(G)iven the stability of copper in water,” he wrote, “this may be a suitable disinfectant that can be applied to irrigation water for control of microbial contaminants on farms.”

Tests also have determined copper ionization to be effective against bacterial fruit blotch in the transplant house. In a scientific article, University of Florida professor Donald L. Hopkins and biologist Constance M. Thompson wrote: “Ionized copper provided control at a copper concentration that was 800-fold lower than with the cupric hydroxide.  This was probably because of the high solubility of the ionized copper and the positive charge of the ion that attracted the bacteria. With the ionized copper, there also is much less copper applied, which should reduce run-off of copper onto the soil. Ionized copper easily could be incorporated into the overhead irrigation systems used by many transplant growers.”

In an abstract presented as a poster to the American Society for Microbiology, Dr. Otto D. Simmons III of N.C. State University found that “Copper provides a stable disinfectant residual in water and appears to be relatively effective for bacteria and viruses.”

Water Education Alliance