UV-assisted Electrochemical Treatment of Landfill Leachate in a Continuous Flow Reactor

A magnified continuous-flow integrated reactor was developed and UV-assisted electrochemical (UAE) oxidation was adopted to treat leachate from a municipal sanitary landfill after biological process. The effects of hydraulic retention time and applied electric current density on the removal of COD_Cr and NH₃-N were investigated, and UAE process and single electrochemical process compared to observe the synergetic effect. Based on analysis of UV-vis spectra (200~500 nm) and GC/MS, it was found that many small organic molecules such as organic carboxylic acids were generated in the process, which could be responsible for the improvement of biodegradability. The results showed that UAE process could treat landfill leachate effectively. Without pH adjustment and electrolyte addition, 74.3% of COD_Cr and 94.9% of NH₃-N could be degraded in the UAE process at a retention time of 85 min and electric current density of 21.2 mA/cm². Simultaneously, the BOD₅/COD_Cr of leachate could reach at about 0.6, and its biodegradability increased by about 12 times.