The Effects of Aeration and pH Adjustment on Copper Corrosion

Generally, ground water contains high levels of dissolved CO2 due to the decay of organic matter and the respiration of plant roots (Freeze and Cherry, 1979). Ground water containing high levels of CO2 can be correlated to significant corrosion of the piping material in water distribution systems. The research objectives were to investigate the relationships between CO2, pH, and copper corrosion as well as project the effects of aeration (CO2 stripping) on copper corrosion in ground water sources. Electrochemical techniques and by-product release were utilized to obtain experimental evidence. The addition of CO2 and HCl to Brookings tap water decreased the pH and consequently increased the by-product release when compared to unaltered Brookings tap water (control). However, electrochemical corrosion rates indicated that CO2 addition tap water (pH~7.7) acted similar to the control tap water (pH~8.6), while HCI addition tap water (pH~7.7) was substantially different when compared to the tap water (pH~8.6). Research on eight eastern South Dakota small water treatment systems indicated that increasing the pH by aeration or NaOH addition substantially decreased the by-product release concentrations. However, by-product release concentrations increased as the initial alkalinity increased, which indicated the method utilized to 1ncrease the pH becomes important