Microbial characterization during aerobic biological treatment of landfill leachate (Tunisia)

Jebel Chekir landfill leachate (Tunisia) treatment was carried out using an aerobic pilot unit with three immersed and fixed biofilms reactors. A preliminary analyses indicate a high biodegradable fraction in the leachate (BOD5/COD = 0.4), which implies that biological treatment process can be applied. The treatment system and performance was investigated at different organic loading rate. Performance results obtained during this study indicate a significant organic matter reduction; between 60 and 90% of TOC reduction was obtained. The microbiological analyses indicate that four bacterial groups were responsible for the biological treatment — Actinomycetes, Bacillus, Pseudomonas and Burckholderia. The inoculation and treatment of raw leachate by bacterial isolates reduced TOC concentrations. The maximum TOC reduction by Pseudomonas isolates was of (70%), whereas Actinomycetes isolates, Bacillus isolates and Burkholderia isolates gave 69, 69 and 77% TOC reduction respectively. However, a consortium containing a mixture of the bacterial isolates inoculated in the raw leachate, reach TOC yield of about 84%.