Landfill leachate treatment using combined fish scales based activated carbon and solar advanced oxidation processes

Abstract

The depuration of landfill leachate (LL) was evaluated by solar advanced oxidation processes (AOPs) (photo-Fenton + O3 and photo-Fenton + O2) and adsorption processes, using activated carbon made from fish scales, as either post-treatment or pre-treatment of advanced oxidation process. Also, the effect in the reduction of toxicity of LL depurated under these methods was evaluated. The activated carbon Brunauer-Emmett-Teller (BET) surface area is 1.8329 m2/g and the adsorption average pore width is 12.79833 nm, considered as a mesoporous material. When AOPs were used as treatment and adsorption was used as post-treatment of the LL, a removal of 67%, 98%, 98.9%, 83.3% and 99.6% of chemical oxygen demand (COD), colour, copper, iron and ABS254, respectively, was obtained. When the adsorption process was applied as AOP pre-treatment, the removal of organic matter was better in comparison to the results of the adsorption process as AOPs post-treatment. This resulted in a removal of COD, colour, copper, iron and ABS254 of 75.4%, 99.4%, 94.4%, 68.3% and 98.1%, respectively.When the AOPs were followed the adsorption process, a germination index (GI) of 126%, 122% and 116% was obtained. This was higher than the results obtained by LL treated with PF + O2 in a solution concentration of 1%, 3% and 10%, respectively. When PF + O3 was used at a concentration solution of 1%, 3% and 10%, similar GI values were obtained (122%, 113% and 114%, respectively). The EC50 is very low for raw LL, but this value increases as the LL is treated. A very high EC50 is obtained for the adsorption process and for AOPs following the adsorption process, going from 1.8 to 21.0 V/V.Adsorption as pre-treatment helps removing colour and metals from LL, thus enhancing the performance of solar AOPs.