Date of Award
8-2025
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Environmental Engineering and Science
Committee Chair/Advisor
Sudeep Popat
Committee Member
David Freedman
Committee Member
David Ladner
Abstract
The practice of separating urine at a building scale, rather than mixing with domestic wastewater to be treated at water resource recovery facilities, allows for concentrated urine to be directly treated with the aim of resource recovery. However, source separation and treatment present challenges during separation, storage, and transport. This study evaluated the use of hydrogen peroxide-producing electrochemical cells, which represent a technology that uses electricity as an input, to stabilize urine through cathodically produced peroxide to enable downstream water and nutrient recovery. The electrochemical cells have been previously shown to stabilize urine with electrochemically produced peroxide as an effective biocide that ceases enzymatic and biological activity in source-separated urine at concentrations in a few hundred to thousands of mg/L. Electrochemically treated urine with residual peroxide may be stable for a longer duration, thus allowing for processes for both water and urea recovery to follow. The effectiveness of urease inactivation by the electrochemically produced peroxide is important to understand, as it will form the basis for scaling up the technology and determining process operational parameters. The concentration of peroxide collected in urine is affected by: 1) the retention time of urine within the cell, and 2) the magnitude of the current density applied to the cathode, where peroxide is produced. Thus, this research evaluates the effect of these two parameters via systematic use of operational conditions to determine the effectiveness of peroxide at inactivating urease. These two conditions can then be tuned for a given expected concentration of urease in the urine. The results presented confirm iv that the concentration of peroxide is directly related to the effectiveness of inactivating urease, where the amount of urease present corresponds with the concentration of peroxide needed for effective stabilization. Additionally, the higher the amount of current density applied through the electrochemical cell, the better the urea stabilization. The challenge of increased retention time in the urine processing system that comes with storage and transportation was further studied through introducing urease into stabilized urine after different storage times, and it was determined that the longer the urine is stored, the more the current density that will be necessary, since the electrochemically produced peroxide will start to degrade. These results thus provide further understanding of the process that will lead to the development of large-scale treatment processes.
Recommended Citation
Covert, Brooke E., "Effectiveness of Electrosynthesized Hydrogen Peroxide in Urease Inactivation for Stabilization of Source-separated Urine to Recover Urea" (2025). All Theses. 4576.
https://open.clemson.edu/all_theses/4576