TECHNOLOGY FOCUS - ENVIRONMENT - Preferred Process: The ground water flows through the housing via an inlet and a gradient flow of the ground water is maintained through the matrix and in the direction of an outlet. The bacterium is capable of degrading trichloroethylene (TCE). Several biocarrier complexes are placed with their outlets adjacent to the screen zone of a well so that water flowing into the well passes through the biocarrier complexes. Contaminated waste water from an above-ground reaction vessel is passed through the biocarrier complex. Two biocarrier complexes with different bacterial strains capable of degrading different pollutants can be used. The matrix comprises microspheres. The bacteria are multiplied at least until log growth phase is attained and are contacted with the ground water before they occupy the whole surface area of the matrix. WIDER DISCLOSURE - The process can also be used to treat polluted soil or industrial waste streams.    EXAMPLE - A culture of trichloroethylene (TCE) degrading bacteria (Pseudomonas) was isolated and cultivated on liquid mineral medium and enriched with 0.2 ml unleaded gas and 20 microliter TCE. Polyclonal antibodies directed against the bacteria were raised in rabbits and used to coat polystyrene or glass microspheres with a variety of binding agents suitable for affinity columns used to prepare the matrix material for binding the antibody. The antibody bound microspheres were then washed and incubated with a log phase suspension culture of bacteria in a culture vessel. A rotary shaker was used to maintain mixing and movement of the bacteria culture relative to the microspheres. The microsphere/antibody/bacterium structure was then introduced into a sterile housing which had at least one inlet and one outlet sealed with glass wool to prevent loss of the beads but permit passage of the liquids. Sterile liquid bacteria culture media was used to incubate the microsphere/bacteria units and encourage growth and colonization of the bacteria onto the microspheres. The resulting functional unit of the housing with active bacterial growth was referred to as the biocarrier complex.    Several biocarrier complexes were positioned in situ adjacent to and in communication with a screen zone of an extraction well. Groundwater contaminated with TCE was drawn into one or more biocarrier complex inlets and exposed to the active bacteria. The efficiency of degradation was controlled by concentration of other hydrocarbons, temperature, pH and available nutrients and efficiency was verified by chromatographic techniques or other measurements for determining TCE levels in the treated groundwater.