Electrolytic destruction of urea in dilute chloride solution using DSA electrodes in a recycled batch cell

The destruction of urea, its fate and influence on levels of active chlorine as well as formation of byproducts during electrolytic treatment of urea solutions was studied. Treated solutions designed to simulate typical concentrations in dairy manure lagoon water, contained initial concentrations of urea up to 750 ppm (mg L-1), chloride from 100 to 400 ppm, and 2000 ppm NaHCO3. Current from 0.6 to 2.5 A (34–141 A m-2) was applied using oxide-coated titanium electrodes in a bench scale electrolysis device. Current and energy efficiencies of urea destruction increased with temperature and initial concentrations of chloride and urea. These parameters also affected the concentrations of oxidized chlorine species during treatment. Residual nitrogen was comprised of a constant fraction (0.07) of urea nitrogen oxidized to nitrate over the temperature range studied (16–34.5 C). Chlorate was also formed as a byproduct of electrolysis.