Application of Isotopic Analysis of Copper in an Engineered Water and Wastewater System

摘要

The Girdwood Water and Wastewater Treatment Facility (GWWTF) has regulatorily driven copper concentration limits on its effluent discharge. A change in the regulations could make it difficult for the GWWTF to achieve compliance with a new lower limit. This study was undertaken to attempt to identify the source copper using copper isotopes, and to represent the first step in determining if isotopic signature of copper can provide any additional insight into the understanding of copper in an engineered system. Total copper and copper isotopes were sampled within the wastewater collection basin, drinking water wells, natural water environment (creeks), influent, effluent, and recycled activated sludge (RAS) within the GWWTF. Mass balances using the diurnal flow of the collection system were calculated to determine the concentration of each isotope sample. These results showed that the total copper results and the corresponding isotope ratios follow the same general plot pattern. The GWWTF effluent has a heavier isotopic signature than the influent, and the RAS has an even lighter isotopic signature than the influent. This study was not able to conclude that higher copper concentrations correlate to heavier isotopes; however, this should be studied further. This study concluded that the lighter copper isotopes preferentially bind to ligands within the RAS due to biological respiration; therefore, yielding a heavier isotopic ratio for the effluent. This conclusion could lead to being able to identify wastewater contribution via its isotopic signature within the receiving water body.