Nutrient media was trickled from the sump to the top of the reactor using a peristaltic pump (Watson Marlow Qdos30 Universal Pump). A 125-micron mesh filter was installed in the media line connecting the peristaltic pump and the reactor. The filter stops the larger particle size solids from entering the reactor, which was the modification made after the clogging of the BTF reactor in an earlier study . The filter was cleaned regularly. A relief valve with a set point of 100 mbar was installed before the filter. The relief valve provided safety in case the peristaltic pump was running, and the filter got clogged. The pH in the nutrient media sump was measured using a digital pH meter with the probe (INTELLICAL PHC735, HACH Lange) mounted in the sump. The outlet flowrate of the gas was measured using a positive displacement type gas flowmeter (BPC ® µFlow, BPC Instruments AB, Sweden).