Cascade bioreactor with submerged biofilm for aerobic treatment of Tunisian landfill leachate

► We determine main pollutants in Tunisian landfill leachate. ► We investigated the treatability of Tunisian leachate by a cascade bioreactor with submerged biofilm. ► We examine pH effect on bio-treatment performances. ► COD was efficiently removed with no significant pH effect while pH adjustment to 7.5 improved the nitrogen removal to 80%. ► Bacillus, Actinomyces, Pseudomonas and Burkholderia genera were isolated showing high carbon and nitrogen degradation.