NOVELTY - Recovering volatile and non-volatile products from a substrate-laden influent stream using microorganisms growing in a rotating bioreactor contactor, where the bioreactor includes a vessel, a shaft, many axially spaced-apart, growth plates, and means, comprises: operating the bioreactor as an aerobic, facultative or anaerobic reactor; feeding the stream past the plates so that the plates are partially submerged within the stream, where, as they grow, the microorganisms convert the substrate to volatile products and accumulate biomass; and passing a stripping gas past the plates.    USE - The process (p1) is useful for recovering volatile and non-volatile products from a substrate-laden influent stream using microorganisms growing in a rotating bioreactor contactor.    ADVANTAGE - The process: utilizes large retained biomass population as a fixed film; removes inhibitory end products while they are produced; provides ease of harvesting the biomass; is economical; and exhibits low energy inputs.    DETAILED DESCRIPTION - Process (p1) for recovering volatile and non-volatile products from a substrate-laden influent stream using microorganisms growing in a rotating bioreactor contactor, where the bioreactor includes a vessel, a shaft mounted for rotation within the vessel about a shaft axis, many axially spaced-apart, growth plates attached to the shaft, where each of the plates has surfaces to which a fixed film of the microorganisms are attached, and means for rotating the shaft and plates about the axis, comprises the simultaneous steps of: (a) operating the rotating bioreactor as an aerobic, facultative or anaerobic reactor; (b) feeding the influent stream past the growth plates so that the growth plates are partially submerged within the stream, where, as they grow, the microorganisms convert the substrate to volatile products and accumulate biomass; and (c) passing a stripping gas past the growth plates to harvest the volatile products as stripped gas. An INDEPENDENT CLAIM is also included for a process (p2) for concentrating the chemical constituents of a stripping gas stream, however the stripping gas stream may have been produced, comprising (a1) conveying the stripped gas to an upstream side of a membrane disposed within a plenum, where the membrane has a high permeability rate for water and a lower permeability rate for the stripping gas, and the stripping gas stream comprises stripping gas, water vapor, and ammonia stripped gas, (b1) applying a differential pressure between the upstream side of the membrane and an opposite downstream side of the membrane, where the water vapor passes through the membrane to the downstream side of the membrane as water vapor permeate within plenum gas, and the gas on the upstream side of the membrane becomes depleted of water vapor as plenum retentate gas, and (c1) combining the plenum gas formed in step (b1) with the retentate gas that is deficient in condensate product to form a combined stripping gas.