Organic matter and nutrients removal from landfill leachate by airlift aerobic three-phase fluidized bed reactor

The treatment of leachate from the Antanas Landfill in the municipality of Pasto, Colombia, was evaluated by means of aerobic three-phase airlift fluidized bed reactors with internal circulation (ATPAFBRWIC) with an external and internal diameter ratio of 2 and an individual effective volume of 53 L. Silica sand was used as a carrier at a concentration of 104 g L⁻¹, and the reactors were operated with hydraulic retention times (HRT) of 1, 2 and 4 h. For a period of 45 days, the following parameters were monitored at the influent and effluent of the reactors: biochemical oxygen demand (BOD), chemical oxygen demand (COD), total phosphorus (TP), total ammonia nitrogen (TAN), total Kjeldahl nitrogen, nitrites and nitrates, where the respective average concentrations recorded in the influent were 4225.9, 7115.2, 14.1, 1664.1, 1591.1, 0.41, and 31.8 mg L⁻¹. The best performance in the removal of organic matter and nutrients was recorded for a 2-h HRT, with average removal efficiency of 52.9% for BOD and 26.8% for COD, and 52.5, 5.6, and 56.2% for TP, TAN, and nitrates, respectively. The low volumes required for ATPAFBRWIC suggest their potential use as compact leachate treatment units.