Abstract
The use of electrochemical processes and technology has been a focus for the energy conversion and storage fields, as technologies ranging from batteries to fuel cells and electrolyzers have received significant attention as cutting-edge and advanced next-generation technologies. To date, the application and development of electrochemical technologies for water and wastewater treatment needs have been limited to specific niches; for example, electrochemical technology has been a focus for non-membrane-based desalination (e.g., electrodialysis or capacitive deionization) and for electrocoagulation of metals and organics, as a replacement for chemically-driven coagulation. However, electrochemical processes and technologies offer a much greater range of possibilities for wastewater treatment needs and goals. From chemical-free disinfection to electrocatalytic conversion of contaminants to recovery of critical nutrients, electrode engineering, control of operational voltage and current windows, and optimization of device design can all be used to address key problems in wastewater treatment. In our research group, we focus the use of electrochemical approaches to address the removal of key contaminants and enable a chemical-free disinfection step for remote and rural wastewater treatment needs in the agriculture and aquaculture sectors. In this talk, I will discuss our ongoing work and recent results on electrochemical approach, electrode engineering, electrochemistry experiments, and device development for the off-grid treatment of aquaculture wastewater for the goals of ammonia removal and disinfection, as well as the off-grid treatment of surface water for irrigation uses, where the goal is on-demand disinfection. Electrochemistry studies for aquaculture wastewater treatment using graphite and graphite-supported PtRu films as the anode demonstrate that the presence of PtRu reduces the voltage required for ammonia oxidation. When graphite is used as the cathode, the disinfectant molecule hydrogen peroxide is produced, suggesting electrochemical disinfection is possible in parallel with ammonia oxidation. In addition, the electrode configuration can be used to generate chlorine on demand, providing an alternate route for disinfection. For both water scenarios, we investigate the roles of electrode type, electrochemical operating parameters, and water chemistry parameters. In addition, our research has included several field site studies to demonstrate performance of our flow electrochemical cells for natural water samples.