Process for chemical modification of reactants by microbes

A process for chemical modification of a reactant by microbes, said process comprising:

• providing a particulate material dispersed in a dispersing fluid wherein the particulate material has a specific gravity less than the specific gravity of the dispersing fluid and wherein the particulate material comprises a polymeric carrier and microbes attached to the carrier;
• and
• establishing a flow of the reactant through the particulate material,
• wherein the flow is effective to contact the reactant with the microbes for a time sufficient to chemically modify the reactant,
• provided that, when said process is carried out under conditions conducive to anaerobic microbe viability, the particulate material has an operating interfacial surface area of from about 2,000 to about 240,000 square meters per cubic meter of particulate material volume and
• provided that, when said process is carried out under conditions conducive to aerobic microbe viability, the particulate material has an operating interfacial surface area of from about 1,000 to about 30,000 square meters per cubic meter of reactor volume.