The rotating trommels are installed upstream of installations of selection municipal solid waste and maintain the screening of MSW exploiting the different size from they possess. They have the function of separating the feed stream into two streams. The separation of the individual parts placed in a current of fall, properly fed, takes place according to the different particle sizes.
In this phase, the individual parts behave seperately parts having sizes lower than the diameter of the holes of the network sieving fall to the bottom of the machine, the parts having size greater than the diameter of the holes network sieving advancing upwards of the machine, following the rotational movement, in the direction of exit and fall into the discharge hopper arranged to the surroundings great.
They thus generate two flows: the undersize flow and the oversize fraction flow