Disinfection of urine by conductive-diamond electrochemical oxidation

This work focuses on the application of electrolysis with diamond anodes for the disinfection of urine. To do this, a synthetic human urine was polluted with Escherichia coli and Pseudomonas aeruginosa and then, it was electrolyzed at current densities within the range 0–100 A m−2. Results show that it is possible to disinfect completely the effluent even at applied electric charges lower than 2 kAh m−3, regardless the current density applied. This good performance is related to the production of powerful oxidants from the oxidation of the ions present in synthetic urine. Likewise, these species also react with the organics contained in urine (urea, creatinine and uric acid), favoring their degradation. The process efficiency for both microorganisms and organics is higher when working at low current densities. The removal of organics leads to the release of significant amounts of nitrogen in the form of nitrate which are later electroreduced to ammonium, that, in turn, reacts with the electrogenerated hypochlorite, favoring the production of chloramines (which can also contribute to the disinfection process). Regarding the mineralization, TOC removal higher than 90% can be achieved but higher applied electric charges than those required for disinfection have to be applied (around 30 kAh m−3).