NOVELTY - Two auxiliary electrodes (4) with main electrode (3) in between, are equipped in processing tank (15). Ground electrode (24) is provided in tank at specified distance from main electrode. Water component detection signal is output based on time lag of threshold fall of square wave voltage in main electrode and square wave voltage of specified phase, frequency applied to auxiliary electrodes, respectively.    USE - For processing organic refuse disposed from home, restaurant.    ADVANTAGE - Processing of refuse is carried out efficiently, since the water component detection signal is output based on based on time lag of threshold fall of square wave voltage in main electrode and square wave voltage of specified phase, frequency applied to auxiliary electrodes, respectively. Water component is detected accurately using high frequency current flowing through RC circuit which passes via the material to be processed, main electrode. The material in the tank is maintained at controlled atmosphere and durability of main electrode for detection of water component is improved. Staining and due formation is prevented since the partition layer and the tank wall are made of non-conductive material. Since the moisture content of the material accommodated in the tank is adjusted based on the obtained result, favorable fermentation is ensured.    DETAILED DESCRIPTION - The processing tank wall is made of non-conductive material. The ground electrode also serves as stir unit for the material to be processed and is made of metal. RC circuit passing via dielectrics, water film along the partition (2), is interrupted with potential of auxiliary electrode. The standard square wave voltage is supplied to the comparator circuit for judging the time lag of threshold fall of the square wave voltage through the resistor. A control unit regulates the temperature and air quantity inside the processing tank and maintains the moisture content of material in the tank to be constant.    DESCRIPTION OF DRAWING(S) - The figure shows the sectional view of processing tank.    Partition (2)    Main electrode (3)    Auxiliary electrode (4)    Processing tank (15)    Ground electrode (24)