TECHNOLOGY FOCUS - BIOLOGY - Preferred Components: The microorganisms in the bio-layer/biopores comprise a mono-culture or a co-culture of at least one of Clostridium ragsdalei, Butyribacterium methylotrophicum, Clostridium Ljungdahlii or Clostridium carboxidivorans.    TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Process: The laved liquid remains within the biopores during the laving cycle. The substrate comprises an asymmetric hydrophilic membrane that defines several bio-pores having effective diameters of at least 1 mu m over at least a portion of the pore length for retaining microorganisms on it as the biolayer and a porous surface on the gas contacting side that presents open ends of the bio-pores to the feed gas. The process (P1) involves a purge cycle where the pressure on the liquid side of the membrane exceeds the pressure on the gas side of the membrane by a sufficient amount such that liquid flows from the liquid contacting side and out of the biopores onto the gas contacting side to flush microorganisms and/or extra cellular material from the bio-pores. The feed gas contains at least one of carbon monoxide (CO) or a mixture of carbon dioxide (CO2) and hydrogen (H2) and the microorganisms convert the feed gas to a liquid product under anaerobic conditions. The microorganisms produce a liquid product comprising at least one of ethanol, n-butanol, hexanol, acetic acid, or butyric acid. The feed gas is synthesis gas having an oxygen concentration of less than 1000 parts per million (ppm), the liquid retention chamber retains a liquid having a redox potential of less than -200 mV, the bio-pores of the membrane retain a microorganism that produces ethanol and a liquid recovery conduit recovers an ethanol containing liquid as the product containing liquid. The asymmetric membrane comprises several hollow fiber membranes. The hollow fiber members extend vertically, the liquid product passes through the lumens of the asymmetric membrane and the feed gas passes across the outside of the asymmetric membrane. The laving cycle occurs at a frequency of 10 seconds to 20 minutes and the duration of the laving cycle lasts from 0.5 seconds to 10 minutes. The substrates are in form of modules containing the asymmetric hydrophilic membrane, where each module sequentially undergoes a laving cycle at frequency of 2-15 minutes, and for duration of 1 second to 10 minutes, and each module sequentially undergoes a purge cycle at frequency of 24 to 1000 hours and for duration of 10 seconds to 10 minutes. The module is subjected to a laving cycle and at least one module undergoes a purge cycle where the pressure on the liquid side of the membrane exceeds the pressure on the gas side of the membrane by a sufficient amount such that liquid flows from the liquid contacting side and out of the biopores onto the gas contacting side to flush microorganisms and/or extra cellular material from the bio-pores. The process (P1) involves regularly maintaining sufficient pressure on the gas contacting side of the modules to transport the feed gas and the liquid products in co-directional flow from the gas contacting side to the liquid contacting side; periodically laving the bio-layer in a portion of the modules with a laving cycle by decreasing the pressure of the gas contacting side relative to the liquid contacting side so that liquid from the liquid contacting side laves into the biopores; periodically purging the biolayer in at least one of the modules with a purge cycle where the pressure on the liquid side of the membrane exceeds the pressure on the gas side of the membrane by a sufficient amount such that liquid flows from the liquid contacting side and out of the biopores onto the gas contacting side to flush microorganisms and/or extra cellular material from the bio-pores; and alternating the modules that are subjected to the laving cycle and the purge cycle so that all of the modules periodically undergo laving and purging. The process (P1) involves sequentially changing the modules that are subjected to the laving cycle.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The asymmetric membrane comprises a hydration layer in the form of a semi-permeable skin on a porous polymer that provides the bio-layer, the semi-permeable skin having a thickness of less than 10 mu m and a porous polymer defines the gas contact side of the member, the porous polymer layer having a thickness of at least 50 mu m and defining the gas contact side of the membrane. The semi-permeable skin is rated at a nominal MWCO of less than 300 kDa and the porous polymer defines bio-pores with effective diameters that do not exceed 100 mu m. The asymmetric membrane is a composite membrane comprising a semi-permeable skin layer of one material as the hydration layer over a porous substrate of another material to provide the biopore layer, the two layers may be joined by thermally fusing or any other method that will maintain the integrity of the composite structure. The bio-layer and hydration layer comprise the same material. The asymmetric membrane consists of a semi-permeable skin and porous polymer both comprising polysulfone, polyethersulfone or polyvinyl chloride. EXAMPLE - No suitable example given.