DISSOLVED COPPER REMOVAL BY ELECTROWINNING PROCESS FROM WASTE BRINE SOLUTION
Open Access
- Author:
- Tang, Linlin
- Graduate Program:
- Environmental Pollution Control
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- March 13, 2018
- Committee Members:
- Yuefeng F Xie, Thesis Advisor/Co-Advisor
- Keywords:
- Copper Removal
Electrowinning
Waste Brine - Abstract:
- Copper in sewage sludge is regulated under the land application regulations by the United States Environmental Protection Agency (USEPA) in 1994. To comply with EPA regulations, Penn State University has been sending their sewage sludge to a landfill due to high copper concentrations for the past 30 years. A previous study indicates that the main source of copper was the corrosion of copper in the University’s steam heating systems. The copper in condensates were captured by the ion exchange softening process and released into the university sanitary sewer systems through the waste brine solution. This study focused on removing dissolved copper from synthetic water samples and actual waste brine solutions which generated from Penn State University’s Steam Plant. To aid in copper removal, a lab scale electrowinning process was constructed. At first, synthetic water samples were prepared for the test had similar copper concentration as the actual waste brine solution. Various levels (0 – 4 M) of sodium chloride were evaluated in this study. The results indicated that the concentration of sodium chloride plays a major role in copper removal. More than 90% of copper reduction could be achieved after three hours of reaction at an appropriate salt concentration (0.04 – 1.5 M). Several electrochemical parameters, distance between electrodes and the voltage applied into the system, were studied and verified. Both of them play important roles in copper removal. A significant positive correlation existed between voltage and maximum copper reduction. Current efficiency decreases with increasing time of electrowinning, and it is low, only 14 – 23%. Two types of internal circulation reactors were constructed for copper electrowinning test. One has three square plate electrodes, two for anodes, one for cathode. Another use aluminum or titanium/platinum alloy basket electrode as cathode, anode still use graphite rod electrode. The copper remove efficiency for both reactors lower than 55% and some blue flocs were precipitated out. A bench scale test using batch reactor was conducted using actual waste brine solutions collected at University East Steam Plant. Around 50% of copper reduction achieved after three hours of reaction, which is much lower than the remove efficiency of synthetic water. 85% of copper reduction achieved after three hours of reaction, with high initial copper concentration (221 mg/L). High salt concentration (2.0 – 2.5M) and low copper concentration of actual waste brine water (6.5 – 63.5 mg/L) are likely the reasons. The extracted copper did not stick to the electrode very well, but those copper can be removed completely using a bag filter. This research will provide us with a better understanding of the process of copper removal by electrowinning process in wastewater treatment and assist Penn State University in complying with the rules of land application.