The drum is the heart of the entire GREENDRUM system. Our model 512 has a 5’ wide by 12’ long drum, with a capacity of 6 cubic yards. It is made of steel and is encased in 2” foam insulation. The foam helps to retain heat in the winter and isolate the compost from the heat of the sun in the summer. The chemical breakdown of compost provides all the heat needed to raise the temperature to 131 º F, the required temperature for pathogen reduction. The foam is painted with a white elastomeric coating that protects it from UV rays and other physical damage. The drum is turned by a motor, which turns a large chain (similar to a motorcycle chain), which clings to teeth fixed to the drum. This motor is turned on and off by a Torque Panel. The Torque Panel has a timer function and can be set up to turn with out supervision. The drum is designed to rotate at a rate of four revolutions per hour. Two saddles support the drum; the part of the drum resting on the saddles does not have foam on it. The entire apparatus is mounted to a trailer.
The GREENDRUM composting system consists of five main pieces of equipment: (1) the mixer, (2) the auger, (3) the fan, (4) the control panel, and (5) the drum:
The mixer has two horizontally oriented augers, which mix food with the amendment: sawdust and woodchips. The mixer is equipped with a lid and a safety lockout switch that turns the mixer off when opened. It is also equipped with a guard on the discharge chute of the mixer.
After the food/woodchip/sawdust mixture leaves the mixer, it drops onto the auger and travels up a gradual incline into the drum.
The Control Panel
The control panel has switches to control the motors of the mixer and the conveyor. There is a separate start and stop button for both. The panel also has an emergency stop for the entire system. There is also a main power switch for all of the equipment. This switch allows the user to turn off and lock out power to the system when doing repairs, cleaning the equipment, etc.
The fan is one of the most important parts of the GREENDRUM system. Oxygen is the most important ingredient in compost, because it is oxygen that allows our system to be both aerobic (uses oxygen) and thermophilic (high temperature). The fan is designed to blow 120 CFM at 0 inches static pressure. The fan needs to be running at all times, except for when unloading or during maintenance.