Fig 3 shows the commercial plant process diagram, which implements a closed loop system principle. It can be
seen that condensed water from the condenser entering the water treatment plant is being fed back to the boiler for
steam supply. At the beginning of the batch, waste is being fed into the reactor to undergo a hydrothermal reaction
with saturated steam supplied from the boiler, while being stirred by a rotor unit to obtain a homogeneous product.
After reaching intended temperature, the boiler is set to maintain the temperature for a certain holding period. The
hydrothermal treatment is finished by bleeding the pressurized steam to the condenser until the reactor reaches
atmospheric pressure. The product can then be pushed outside by rotating the rotor blades acting as a screw
conveyor.
III. Experimental Method
A. Hydrothermal Treatment Experiment
The MSW hydrothermal treatment experiments were performed in Hokkaido, Japan. The raw MSW was
supplied by a local town, visually contained much plastics since most of the local organic wastes were separated for
composting. The sampling was then performed based on the Japanese standard JIS K0060.
Three main parameters of processing – (1) the pressure and its related steam temperature, (2) the holding period,
and (3) the amount of MSW – were varied as shown in Table 1 to understand the characteristic of the system against
MSW.