Electrochemical Disinfection of Liquid Human Waste for Developing World Application
The ED system was tested with the expected daily output of urine and flush water from one person and the solids/liquids interaction with feces was simulated to obtain the desired fecal contamination. E. coli was chosen as the disinfection indicator with starting concentrations ranging from 2.5 x 104 – 1.4 x 107 MPN/mL. As shown in Figure 1, disinfection was achieved by 110 minutes of processing time at 12 V.
Effective treatment of pathogens is expected to be a function of the production of chlorine containing species and other reactive oxygen species. However, to maintain disinfection in the system after ED treatment, a residual chlorine concentration is desired. Figure 2 shows the total and free chlorine produced over long electrochemical cell run times. Large amounts of chlorine were shown to be produced, however; most is consumed within 24 hours after the cell is turned off.
The ED system has demonstrated effective disinfection of fecal-contaminated liquid waste in simulated field conditions. Continued research will include pilot testing and demonstration of the ED’s effectiveness at killing chlorine resistant pathogens.
Financial support for this work was provided by the Bill & Melinda Gates Foundation.
1. A. Raut, G.B. Cunningham, C.B. Parker, B.R. Stoner and J.T. Glass, in 223rd ECS Meeting (May 12-17, 2013).