Efficient Cu removal from CuEDTA complex-containing wastewater using electrochemically controlled sacrificial iron anode

Abstract

In this study, an electro-replacement/precipitation/deposition/direct reduction (ERPDD) process with scrap iron packed in a Ti mesh cage as a sacrificial anode was investigated for the treatment of wastewater containing CuEDTA complexes. The ERPDD mechanisms were responsible for the removal of Cu from CuEDTA complexes and were verified by a series of experiments using either iron or carbon plates as anodes for the Cu-containing solutions with and without EDTA. A complete Cu removal was achieved with electrical current density applied (1.18–2.36 mA/cm2), whereas only 60% of the Cu was removed without electricity. Dissolved oxygen (DO) was found to have a significant impact on Cu removal. Aeration reduced Cu removal (i.e., only 60% of the Cu was removed), whereas complete Cu removal was achieved with negligible DO concentration under mechanical mixing and N2 purging conditions. Compared to chemical replacement/precipitation (CRP) process, the ERPDD was able to save approximately 60–75% of the total operational costs during the treatment of CuEDTA-containing wastewater, due to the electrochemically controlled dosing of inexpensive sacrificial scrap iron and additional removal mechanisms not found in the CRP process.