The DAD (Dry Anaerobic Digestion) is also suitable for organic waste. Although this technique produces less biogas than the typical wet or semi-dry systems the initial investment and running costs are lower. The process takes place in several gas-tight boxes maintained at a constant 30-35°C through floor heating systems using excess heat from the gas engines. The anaerobisation process is activated by the sprinkling of bacteria- rich leachate water onto incoming screened MSW (<60 mm) or other organic solid waste. The produced biogas consists of a constant ratio of ~ 50-60% CH4 and ~40-50% CO2. After 26 days of anaerobic treatment and biogas production, the anaerobic process is paused for 2 days to render the anaerobic microorganisms inactive. Once inactive, treated materials can be safely removed for further degradation and stabilisation.
Click
here to watch the video for the DAD plant in Naga, Cebu.
