Monitoring of biogas production from fermentation of rice straw using a bubble counting sensor

A bubble counting sensor with an on-line monitoring system was applied to biogas production from fermentation of rice straw. This simple and low-cost sensor was capable of measuring bubble diameter and counts by a photointerrupter and a clock cycle (2441Hz). The detectable range of gas production rate was 0.067 - 10 mL/min. The on-line monitoring system built with a one-chip microcomputer was operated for over 100 days and demonstrated to be promising in monitoring gas production during fermentation processes.