| 摘要 |
<p>Provided are a method and system which use circulation-type hydrothermal reactions to process sludge by methane fermentation in an energy-efficient manner and stably over a long period of time. In this methane fermentation processing method, after the moisture content of the sludge (S) is adjusted to a prescribed level, the sludge (Sa) with the adjusted moisture content level is pumped into a circulation path (14a, 14b) connecting a hydrothermal reactor (11) and a gas-liquid separator (12) and is reduced in molecular weight by circulation for a prescribed period of time at a prescribed temperature and pressure, and the low molecular weight sludge (Sc) outputted from the circulation path (14a, 14b) is retained in a fermentation tank (20). The scale deposit state in the circulation path (14a, 14b) is continuously detected and the prescribed moisture ratio of the sludge (Sa) pumped into the circulation path (14a, 14b) is adjusted in response to the variation of the scale deposit state. Ideally, a flowmeter (31) and a flow rate control valve (32) are provided to control the circulation flow rate of the sludge (Sa) in the circulation path (14a, 14b) to the prescribed flow rate, the scale deposit state is detected from the opening degree of the flow rate control valve (32), or the scale deposit state is detected from the surface temperature of the circulation path (14a, 14b).</p> |
