(EP752909-A1)      A method of reducing the concn. of gaseous or vapour phase organic cpd(s) present in a gaseous stream comprises causing the stream to flow in contact with an interior surface of a water-insoluble, selectively permeable sheet, tubular or envelope-type polymeric membrane, whose permeability to the organic cpd. exceeds its permeability to chloride ion, whilst simultaneously maintaining in contact with an external surface of the membrane an aq. reaction medium contg. biologically active reaction means such as biomass bacteria or algae or other microorganism or immobilised cells capable of reacting with the organic cpd after if permeates from the gaseous stream through the membrane from the interior to the external surface.    USE -   Volatile organic cpds. such as chlorinated solvents and aromatics (dichloromethane, benzene, toluene etc) or opt. substd. alkanes can be treated. The gaseous stream comprises waste gas from an industrial or municipal process and contains several pollutant organic cpds., at least one of which is volatile.    ADVANTAGE -   Large gas-liquid interface and high gas velocities can be obtd. without significant pressure drops observed in biofilters and bioscrubbers. The membrane acts as a barrier between the biomedium and the contaminated gas stream, thus avoiding the entry into the biomedium of cpds. which would hinder biological degradation. Ready control of pH and removal of biooxidation prods is possible. The solutes may be transferred at a higher rate than in conventional systems and microorganisms maintained in a favourable growth environment. The ageing and required renewal of packaging material is avoided. Treatment of cpds with low water solubility is possible. The dimensions of the equipment are more compact and no disposal of sludge is necessary.    (JP9510917-W)      A method of reducing the concn. of gaseous or vapour phase organic cpd(s) present in a gaseous stream comprises causing the stream to flow in contact with an interior surface of a water-insoluble, selectively permeable sheet, tubular or envelope-type polymeric membrane, whose permeability to the organic cpd. exceeds its permeability to chloride ion, whilst simultaneously maintaining in contact with an external surface of the membrane an aq. reaction medium contg. biologically active reaction means such as biomass bacteria or algae or other microorganism or immobilised cells capable of reacting with the organic cpd after if permeates from the gaseous stream through the membrane from the interior to the external surface.    USE -   Volatile organic cpds. such as chlorinated solvents and aromatics (dichloromethane, benzene, toluene etc) or opt. substd. alkanes can be treated. The gaseous stream comprises waste gas from an industrial or municipal process and contains several pollutant organic cpds., at least one of which is volatile.    ADVANTAGE -   Large gas-liquid interface and high gas velocities can be obtd. without significant pressure drops observed in biofilters and bioscrubbers. The membrane acts as a barrier between the biomedium and the contaminated gas stream, thus avoiding the entry into the biomedium of cpds. which would hinder biological degradation. Ready control of pH and removal of biooxidation prods is possible. The solutes may be transferred at a higher rate than in conventional systems and microorganisms maintained in a favourable growth environment. The ageing and required renewal of packaging material is avoided. Treatment of cpds with low water solubility is possible. The dimensions of the equipment are more compact and no disposal of sludge is necessary.