Electrochemical treatability of refractory pollutants in landfill leachate

Landfill leachate treatment is the most troublesome aspect of the landfill management. Investigation of leachate characteristics at two landfill sites in Taiwan showed that the biological processes were inefficient for the treatment of leachate, regardless of whether an anaerobic or aerobic process was used. In addition, conventional flocculation/sedimentation processes were also ineffective for post-treatment of leachate effluents from biological treatment processes. The discharged leachate still contained lots of refractory pollutants and it failed to meet the effluent quality standards of the R.O.C. (COD < 500 mg/L NH sub(4) super(+)-N < 20 mg/L). In an attempt to improve leachate effluent quality, in this study, an electrochemical oxidation process was applied to treat the landfill leachate after biodegradation. Results from both batch and continuous experiments indicate that over 90% of COD and NH sub(4) super(+)-N in the landfill leachate are removed by the electrochemical oxidation process. In addition, the electrochemical oxidation process also demonstrated a good efficacy for the removal of refractory compounds. After electrolysis, the chlorinated organic matters (as TOX) in the landfill leachate was reduced from 19.4 to less than 2 mg C1/L and the BOD/COD ratio of the landfill leachate was also improved from 0.05 to 0.71. These results indicate that the electrochemical oxidation process is a promising process for the treatment of landfill leachate.