The electrolytic treatment of synthetic urine using DSA electrodes

• Urine can be efficiently treated using electrolysis with DSA.
• Low current densities lead to efficient process and prevents formation of chlorates.
• Carbon dioxide and oxalic acids are the main carbon final products.
• Nitrogen is effectively removed through the formation of chloramines and its further oxidation.

In this work, the electrochemical treatment of synthetic urine by anodic oxidation using dimensionally stable anode (DSA) was studied. The influence of current density and temperature on the kinetics and efficiency of anodic oxidation was examined. The intermediates and the evolution of products were also monitored by HPLC and IC. Anodic oxidation achieves the almost total removal of COD, which is mainly transformed into carbon dioxide and oxalic acid. This latter compound explains the occurrence of residual TOC at large current densities. The electrochemical technology also attains a very significant removal of nitrogen, which is transformed into gaseous nitrogen through the formation of chloramines. The increase of current density leads to a decrease in the efficiency of the electrochemical process. Furthermore, the increase of the temperature has no significant influence on the oxidation rate but it contributes to a higher mineralization. The most efficient conditions were found to be low current densities (20 Ah dm−3) and low temperatures (25 °C), which in addition prevents the formation of chlorate and perchlorate ions in the reaction system.