System Description

The GICOM Tunnel Composting System is based on composting organic material in an enclosed vessel: The Tunnel.

After the tunnel has been filled with compost feedstock the door is closed and the tunnel climate control program is initialized. The composting tunnels will be managed with respect to temperature, oxygen and moisture levels to optimize the process, attain pathogen reduction requirements, and meet process objectives.

After tunnel filling and program initialization, the variable speed blower associated with the tunnel starts operating and air is pushed into the aeration floor system within the tunnel. The recirculation route for the air is as follows:

• Air is blown into the concrete plenum located behind each tunnel in the technical area;
• Into the floor piping system;
• Into the composting matrix;
• From the head-space into external recirculation loop ductwork through the open recirculation damper;
• Back through the blower and then back into the plenum.

As the air enters the circulation route, several parameters are measured at several positions in what is referred to as the Input, Return and Total Airstream:

• Air temperature
• Air humidity
• Oxygen / carbon dioxide concentration
• Pressure

* temperature of the composting matrix is measured at several points within the tunnel.

The above parameters are continuously monitored by the process computer software. The software is programmed to control certain variables at certain pre-determined times or points in the course of the tunnel cycle. The speed of the blower and recirculation rate will be manipulated to maintain the desired conditions in the composting matrix.

When called for, the damper arrangement, controlled by a servomotor, permits the continuously variable introduction of the Fresh Airstream (0-100%). This allows for mixing of the recirculated air in the ductwork upstreams of the plenum. When this occurs, a volume of used air equivalent to that newly introduced is exhausted out of the system from the headspace by a damper arrangement.

The Fresh Airstream for the tunnels is drawn from the receiving hall via an overhead ductwork system with managed controls. This system takes the air out of the building on a variable basis. Air is drawn from building space by a dedicated variable speed blower and controls.

The process air exhausted from the tunnel is transported directly to the odour control system.

Brentwood Recycling Systems is Australia’s leading manufacturer of plant and machinery for the Recycling and Solid Waste Industries in Australia, providing everything from full turn-key plant installations to single recycling machines.