Municipal landfill leachate treatment using a periodic biofilter with granular biomass

The paper reports the results of a laboratory scale investigation aimed at evaluating the performance of a periodic biofilter with granular biomass (SBBGR) for treating leachate coming from a mature municipal landfill located in the Apulia region of southern Italy. The results show that the SBBGR was able to remove roughly 80% of COD in leachate, up to an organic loading value of 1.1 kgCOD/(m3od). No further increase in COD removal efficiency was recorded when the high ammonia content (i.e. about 3,200 mg/L) of the investigated leachate was removed by magnesium ammonium phosphate precipitation and the organic loading reduced. The remaining 20% of COD were therefore presumably due to the presence in the leachate of recalcitrant compounds. A reduction of only 10% in COD removal efficiency was recorded when the organic loading value was increased from 1.1 to 4.5 kgCOD/(m3od). Ammonia removal efficiency was very low (lower than 20%) because of the presence of high salinity and inhibitory compounds in the investigated leachate. The process was characterised by very low sludge production (lower than 0.02 kg TSS/kgCODremoved).