In this work we processed a considerate leachate from the landfill of DjebelChekir in Tunisia by the membrane bioreactor technology. Raw leachate analysis shows a high concentration organic as well as a very high concentration in salts especially chlorides and ammonium, controlled parameters are in the order of pH 8.4; 50.5 mS/cm for the conductivity; 14.000mg/lforCOD; 502mg/l forNH4+ and13.800mg/lfor chloride. The treatment system studies is ÂBIOMEMBRAT® technology Âwhich consists of biological reactors associated with a unit of ultrafiltration for the retention of the biomass followed by a reverse osmosis filtration step in order to achieve the Tunisian discharge limits. We conclude fromour study that the performance of the biological treatment reactor can achieve the reduction inCODof the order of79%and ammonium 99.6%. Analysis of reverse osmosis permeatesin the outlet of the plant shows that the controlled parameters are below legal standards Tunisian of direct discharge in the nature. Values and the measured concentrations are in the range of pH6.5, 1.4mS/cmfor conductivity,COD<15mg/l andNH4 +< 2mg/ l correspond to the reduction rate of about 99,5 %. Chloride (Cl-) is of the order of 270mg/l in the outletwith the reduction rate of about 99,5%about 98 %for chloride.