Immobilisation of Anaerobic Microorganisms

This project was devoted to studies in laboratory scale on immobilisation in anaerobic environment. The overall aim was to get knowledge of factors that influence the anaerobic colonisation on supports in a complex industrial effluent as well as practical laboratory methods for making investigations of this kind. Different polymeric supports were tested. The properties of the surfaces were characterised by their wettability and surface roughness. Screening tests have been done for the evaluation of the initial adhesion and long-term biofilm development on small polymeric plates in a continuous, specially designed, anaerobic reactor. The substrate used, was complex effluent water from the wood pulp industry. The analyses of the development of biofilms were performed by fluorescence microscopy and viability tests with ATP measurements. After reactor incubation and biofilm analysis, subsequent tube tests were performed to get information of degrading capability as a function of support material and age. Experiments with packing modules of different kinds were made in somewhat bigger scale for some polymeric materials. Measurements of suspended and attached biomass were made for quantitative comparison. Luminometric method with ATP measurement as a method for estimation of biomass accumulation has shown to be usable. No simple correlations have been found between factors like hydrophobicity characteristics and surface roughness in relation to the development of biofilms. Initial differences in colonisation velocity depending on surface qualities seem to be levelled out in the long run (months). The choice of carrier material, at least if a polymeric one, is more a matter of economical and material strength considerations. From a general point of view, small scale laboratory test methods used here, are practicable to evaluate differences in the start up phase depending on choice of material and the influence of the form of packing modules. This may a tool to decide the carrier material that is most suitable in specific full scale applications. An introductory literature study, covering actual issues of the project, is found in the appendix