Treatment of landfill leachate with aerated and non-aerated submerged biofilters.

A submerged biological filter packed with clayey schists from brick industrial waste as support material was used to treat landfill leachate. The pilot-scale plant consisted of two separated reactors, running in aerated and non-aerated conditions respectively. The leachate was taken from a landfill in Granada (southeast Spain) and was considered as partially stabilized with average chemical oxygen demand (COD) concentrations of 18,683.3 mg COD/L. The efficiency of the system at reducing COD, biological oxygen demand (BOD(5)), total suspended solids (TSS), total volatile solids (TVS), total solids (TS), cations and anions concentrations was tested comparing aerating and non-aerating conditions under several volumic organic loadings (15.7, 25.1 and 31.1 kg COD/m(3)d), a hydraulic loading of 0.7 m(3)/m(2)d and an internal recirculation of 250%. Results obtained showed that the aerated reactor was more effective than the non-aerated reactor in the removal of COD, BOD5 and TS, with maximum efficiencies of 66.7%, 91.2% and 21.7%, respectively. The volumic organic loading of 25.1 COD/m(3)d obtained best results. However, for the removal of TSS and TVS the non-aerated reactor showed better results (42%). The behaviour of different cations (Na(+), K(+), and Mg(2+)) and anions (F(-), Cl(-), Br(-)) was also monitored and a reduction in their concentration in the effluent was detected, in the order of 61% for Ca(2+) and 100% for F(-).