Development of Hybrid Systems by Integrating an Adsorption Process with Natural Zeolite and/or Palygorskite into the Electrocoagulation Treatment of Sanitary Landfill Leachate

The effectiveness of a hybrid approach comprising electrocoagulation (EC) and adsorption (AD) (using natural zeolite and/or palygorskite) processes to treat raw sanitary landfill leachate (SLL) was investigated in terms of color, dissolved chemical oxygen demand (d-COD), nitrate nitrogen (NO3--N) and ammonium nitrogen (NH4+-N) removal. Optimal EC conditions were found with a current density of 30 mA cm(-2), Fe electrode material and pH 8. Implementation of the AD process using zeolite (AD(zeo)) as pre- or post-treatment for EC significantly increased the NH4+-N removal efficiency. The AD(zeo)-EC sequential treatment showed considerably higher color removal compared to the EC-AD(zeo) sequential treatment and was therefore determined to be the optimal sequential treatment. Integration of the AD process using palygorskite (AD(pal)) into the first or middle stage of the AD(zeo)-EC treatment system enhanced the overall NO3--N removal efficiency. The hybrid AD(zeo)-AD(pal)-EC treatment system exhibited the highest simultaneous removal efficiencies of color, d-COD, NO3--N and NH4+-N, corresponding to 95.06 +/- 0.19%, 48.89 +/- 0.89%, 68.38 +/- 0.93% and 78.25 +/- 0.61%, respectively. The results of this study indicate that the AD(zeo)-AD(pal)-EC hybrid system is a promising and efficient approach for treating raw landfill leachate.