Studies on the dynamics of immobilization of anaerobic bacteria on a plastic support

The paper presents a comparative study of the immobilization dynamics of mesophilic and thermophilic anaerobic bacteria. The support used was fine polyethylene particles and the immobilization system was a down flow fluidized bed. The maximum acetoclastic specific activity of the mesophilic bioparticles was of 0.0083 mmol acetate/mg VSS/h while for the thermophilic bioparticles was near zero. The final immobilized VSS content for both system was around 45 mg/g dry support. The substrate affinity determined only for mesophilic bioparticles was of 68 mg COD/1; for the thermophilic bioparticles could not be determined due to the low acetoclastic rates presented. The SEM studies showed that predominantly the bacterial group attached was Methanothrix-like bacilli, and the mesophilic was structurally different from the thermophilic one.