Landfill leachate production and management are identified as one of the greatest problems of sanitary landfill. In this research paper, the effect of the use of bactofugate (B) and the expired fermented milk ‘Lben’ (L) in the biological treatment of Jebel Chakir leachate was studied. Leachate samples were separately inoculated with both raw and reactivated (B) and (L) samples and incubated at 37 °C over 15 days. Both raw (L) and (B) inoculums ensure better results in terms of organic matter removal than the reactivated samples. However, the best removal performances were obtained with (L) inoculum. The chemical oxygen demand (COD) removal reached 50% with an initial COD concentration of 20.8 g L−1, whereas 80% of ammonia nitrogen (NH3-N) removal was recorded. Furthermore, heavy metal concentrations, especially of Cr3+ and Fe2+, were reduced during the treatment with average removal rates of about 90%. Then, further kinetic investigations were performed using the (L) inoculum with an equipped bioreactor with air incorporation. Important COD removal efficiency (46%) was recorded within only 24 h. Heavy metal concentrations were also reduced during this process. The findings indicate that expired fermented milk could be a promising alternative for the biological pre-treatment of landfill leachate.