Copper ion generator cons outweigh pros
Copper ion generators were originally developed decades ago to control biofouling in sea water. Since then, they have been adapted for control of zebra mussels and quagga mussels in fresh water. These invasive mussels breed in massive numbers and attach themselves to hard surfaces. Left unchecked, they can quickly overwhelm intake structures and clog pipelines.
Low concentrations of copper ions added to the water can control invasive mussels. Although copper ion generators are capable of intermittently delivering doses as low as 10 ppb, the Reclamation study found that the copper concentration actually delivered by the generator was highly unstable, bouncing around between 15–50 ppb without manual adjustment. The researchers also found that those higher doses – 150% to 500% the dose recommended by the generator manufacturer – were necessary to achieve significant adult mussel mortality and to inhibit settlement of juvenile mussels, called veligers. Higher doses draw more electricity and deplete a generator’s anodes more rapidly. This can lead to more frequent and costly replacements.
At the end of the experiment, the copper ion concentration in the discharge stream from the generator had deteriorated by 45%. The generator initially averaged 145 ppb but fell to a low of 80 ppb after seven months. The study concluded that, even at the higher concentration, the generator was only capable of treating a flow stream of no more than 200 gallons per minute (gpm), far less than the 2000 gpm suggested by the manufacturer’s manual.
The results of the study were presented by Renata Claudi M.Sc at the 19th International Conference on Aquatic Invasive Species (ICAIS) in Winnipeg, Manitoba on Wednesday, April 13, 2016. The presentation is republished here with permission.