Anoxic digestion based on the endogenous biomass activities has been studied in batch reactor (V = 150 L) for the treatment of landfill leachate of Jebel Chekir landfill (Tunisia). With a retention time of 90 days, the anoxic digestion reactor has shown reductions in BOD5, COD, TOC, NH4-N and TKN respectively by 91%, 46%, 65%, 45% and 63%. Later, the effluent was further treated in down flow cascade in three aerated submerged biological reactors, with 7 days of total retention time. Further reductions in these parameters were achieved in the aerobic reactors and the overall removal efficiencies achieved by the coupled system of anoxic and aerobic reactors were 95% for BOD5, 94% for COD and 92% for NH4+-N. Moreover, post treatment aimed at the removal of heavy metals by adsorption on powdered activated carbon (PAC) was also studied in this work and was found affective to enhance the removal of COD up to a total reduction level of 99.7%.