The purpose of the research was to test the feasibility of using immobilized proteins as highly specific adsorbers of pollutants in waste streams. The Escherichia coli periplasmic phosphate-binding protein served as both a model system for determining the feasibility of such an approach and at the same time was used to produce a cycling ligand adsorber capable of efficiently scrubbing phosphate from a feed stream. Three different procedures for the removal of cadmium from feed streams were developed in this project. A bioreactor for continuous protein production was developed to minimize the cost of protein production. The bioreactor contained immobilized, non-growing E. coli cells. The cell line had been mutagenized and selected for the direct secretion of periplasmic proteins into the medium. The cells contained the gene that encodes the phosphate-binding protein.