Abstract An immobilized microbial cell system was developed and tested for the treatment of industrial wastewater. A consortium of selected aerobic microorganisms was immobilized onto several different support matrices in a packed bed reactor configuration and operated in a continuous process mode. Comparison of the support matrices showed only small differences in treatment efficiency, but significant differences in sludge production and process stability. Porous polymer supports were highly resistant to feedstream upsets and produced 80% lower sludge solids as compared with non-porous supports. These results were seen at both the benchtop and pilot plant scale for treatment of complex industrial waste streams. This technology was applied, in preliminary experiments, to the treatment of a model waste stream simulating wastewater from a Controlled Ecological Life-Support System (CELSS).