2.3. Influence of water volume on digestion
To determine the influence of water volume on biogas production in digesters, 50 g of feeds (rice husks from the four different rice mills) were placed in sixteen different IL conical flasks (i.e. each sample in quadruplicate).
The rice husk in the different digester flasks was moistened with varying volumes (200–500 mL) of water to give feedstock/water ratio of 1:4, 1:6, 1:8 and 1:10 (w/v), respectively.
The digester without water served as a control. To initiate fermentation, 50 mL of the inoculum was added and the sides of the rubber bungs on the flask neck were sealed with candle wax to create anaerobic condition.
Fermentation was carried out at room temperature (30 °C) for hydraulic retention time of 28 days.