MICROBIAL COLONIZATION OF POLYURETHANE FOAM MATRICES IN HORIZONTAL-FLOW ANAEROBIC IMMOBILIZED-SLUDGE REACTOR

This paper presents the anaerobic biomass characterization and the bac terial framework inside polyurethane foam matrices taken from a horizo ntal-flow anaerobic immobilized-sludge (HAIS) reactor treating a gluco se-based substrate. Ultrastructure polyurethane foam analyses carried out using scanning electron microscopy (SEM) in samples treated with h examethyldisylazane showed three different patterns of biomass retenti on inside the polyurethane foam matrices: micro-granules ranging from 270 mu m to 470 mu m were entrapped in the porous medium thin multi-ce llular films were attached to the inner surface, and individual cells adhered to the support. The use of SEM and epifluorescence microscopy permitted inferences to be made on the bacteriological composition of the immobilized sludge formed by different morphotypes (rods, cocci an d filaments) and on the ecological significance of their framework ins ide the matrices. Polyurethane matrices were found to offer excellent conditions for anaerobic growth and retention. favoring the flux of su bstrate and products. Such outstanding characteristics were confirmed by the short start-up period observed during the operation of the HAIS reactor.