电化学氧化对尿液处理过程中消毒副产物的生成控制和去除

Reduction and removal of disinfection by-products (DBPs) residues in the effluents of electrochemical oxidation of urine are the key points to eliminate the potential risk of this technique. In this study, the experiments on electrochemical oxidation of urine were conducted to regulation and control of DBPs production and their post-treatment. The results demonstrated at the current density of 25~100 mA·cm⁻² and power consumption of 40 Ah·L⁻¹, the inflection point of free chlorine concentration from almost invariable to rapid increase (i.e., the chlorination breakpoint) occurred when treating synthetic urine (SU). Before the breakpoint, the competitive inhibition occurred between the ammonia ions and urea chlorination reaction and free chlorine, the concentration of produced DBPs kept at relative low level. After breakpoint, the concentrations of organic chlorination by-products (OCBPs) increased rapidly to the peak value. Thereafter, OCBPs concentrations declined slightly, but most free chlorine transformed into inorganic chlorination by-products (ICBPs) with the main species of chlorate. Overall, at higher current density, electrolysis at the end of chlorination breakpoint could control DBPs production at low level, completely remove ammonia nitrogen and inactivate microorganisms. The residues of DBPs in urine subjected to electrochemical oxidation were further post-treated by adsorption. The results showed that at the activated carbon dosage of 30 g·L⁻¹, the removal efficiencies of the major DBPs dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) were 71.6% and 96.5%, respectively. Therefore, electrolysis process optimization coupled with the activated carbon post-treatment can effectively reduce the DBPs residues in urine treated by electrochemical oxidation.