Support material selection for anaerobic fluidized bed reactors by phospholipid analysis

Many different types of support materials are used in anaerobic fluidized bed in order to obtain high levels of biomass in the reactors. A material is usually considered the most suitable in terms of physical–chemical parameters or reactor performance, but not in terms of microbial adhesion. In this work, two commercial materials were tested as support for anaerobic biomass: perlite and sepiolite. Biofilm accumulation was estimated by two methods, attached volatile solids and lipid phosphate concentration, both determined directly on attached biofilm. The biomass adhesion on sepiolite was higher than the perlite for all the tested initial total organic carbon concentration in the reactors. We have found that biomass measurement method developed directly on attached biofilm is relevant to the amount of living cells. We also discuss the suitability of estimating attached biomass by means of direct measures on biocovered particles rather than on enrichment cultures of free cells detached from the supports.