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

Abstract

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 (ADzeo) as pre- or post-treatment for EC significantly increased the NH4+-N removal efficiency. The ADzeo-EC sequential treatment showed considerably higher color removal compared to the EC-ADzeo sequential treatment and was therefore determined to be the optimal sequential treatment. Integration of the AD process using palygorskite (ADpal) into the first or middle stage of the ADzeo-EC treatment system enhanced the overall NO3−-N removal efficiency. The hybrid ADzeo-ADpal-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 ADzeo-ADpal-EC hybrid system is a promising and efficient approach for treating raw landfill leachate.