Electrochemical Disinfection of Liquid Human Waste Using Potentiodynamic Methods and Controlled Electrode Surface Chemistry

Abstract

Roughly 40% of the world does not have access to appropriate sanitation of human generated waste water. Lack of infrastructure and poverty in developing nations has stymied the deployment of conventional sewage treatment practices. In helping to solve this global issue requires the development of an energy efficient, cost-effective, low-maintenance, and decentralized toilet system that can remediate human liquid waste, or, blackwater. Herein, electrochemical disinfection as a means of treating blackwater is investigated using degenerately boron-doped diamond and Magnéli-phase titanium sub-oxide electrodes. It is found that both can be operated in potentiodynamic modes to control surface chemistry and improve generation of biocidal oxidants such as hydrogen peroxide and chlorinein blackwater containing solutions. Use of a packed-bed electrochemical reactor is also studied in the treatment of blackwater using Magnéli-phase titanium sub-oxide granular electrodes. It is found that bed-height, flow-rate, and blackwater chemistrycan greatly affect the effectiveness of electrochemical disinfection and stability of a packed-bed electrochemical reactor. Overall, these results highlight how existing electrode materials can be modified or controlled in-situ to inhibit fouling, generateoxidants using less energy, and therefore disinfect blackwater pathogens more effectively.