A pilot-scale electrocoagulation-treatment wetland system for the treatment of landfill leachate

In the present study, the technical feasibility of an electrocoagulation-treatment wetland continuous flow system, for the removal of organic matter from landfill leachate (LL), was evaluated. The response surface methodology (MSR) was used to assess the individual and combined effects of the applied potential and distance between electrodes, on the removal efficiency and optimization of the electrocoagulation process. The hybrid treatment wetland system consisted of a vertical flow system coupled to a horizontal subsurface flow system, both planted with Canna indica. For a chemical oxygen demand (COD) concentration -without pretreatment of 5142.8 +/- 2.5 mg L-1, the removal percentage for the electrocoagulation system was 79.4 +/- 0.16%, under the optimal working conditions (Potential: 20 V; Distance: 2.0 cm). The COD removal efficiency in the treatment wetland with Canna indica showed a dependence with the hydraulic retention time, reaching 59.2 +/- 0.2 % over 15 days. The overall efficiency of the system was about 91.5 +/- 0.02 % removal of COD. In addition, a decrease in the biochemical oxygen demand (94.8 +/- 0.14%) and total suspended solids (88.2 +/- 0.22%), also related to the contamination levels of the LL, were obtained. This study, for the first time, shows that the coupling of electrocoagulation together with a treatment wetland system is a good alternative for the removal of organic contaminants present in LL.