Molecular microbial diversity and technological features of a packed-bed biofilm digestor capable of olive mill wastewater anaerobic bioremediation and valorization

The stability, bioremediation efficiency and methane productivity along with the biology of a granular activated carbon (GAC) packed-bed biofilm reactor capable of olive mill wastewater (OMWs) anaerobic digestion were investigated. The GAC-reactor was found to be an effective, reproducible and stable OMW digestor. We observed temporal shifts in the microbial community composition, based on 16S rDNA sequence diversity, when the biofilm community structure was compared with that of the inoculum after 9 months of operation. In particular, specific microbial populations were enriched during the course of the study and they mainly consisted of Proteobacteria, Flexibacter-Cytophaga-Bacteroides, and sulphate-reducing bacteria. The dominant sequence among Archaea (70% of clones) was closely related to Methanobacterium formicicum.