Composting Tunnel Siderno
TM.E. SpA - Termomeccanica EcologiaSiderno | Reggio Calabria - Italy
- System description: Tunnel composting
- Waste processed: Mixed and source separated organic
- Plant capacity: 32,000 t/year
Tunnel composting technology is used to process organics from mixed and source-separated municipal waste. The biological process takes place inside closed reactors, consisting of tunnels made of reinforced concrete with an aeration system integrated into the fl oor. The plant uses biotunnel composting technology for the biological treatment of or-ganic waste deriving from screened mixed municipal waste, as well as organic material deriving from source separation. The process takes place in six closed reactors, consisting of reinforced concrete tunnels with an aeration system integrated in the floor. The air blown into the material through the floor is in part re-circulated inside the tunnel and in part sent to the odour control system. Air coming from the wastesorting areas is used as fresh process air in the tunnels, so the total volume of waste air is lowered without negatively affecting the ventilation of the buildings. A sophisticated collection and treatment system for leachates ensures correct tunnel drainage and allows the liquid to be re-used for moisturizing the processed material by means of nozzles set up under the ceiling of each tunnel. Once the tunnel has been loaded with the wheel loader, its special door is closed and the process begins. At the end of the treatment the tunnel is emptied and a new cycle begins. A computerized control system, including visualization on PC with colour graphics, monitors the process and keeps its parameters within preset ranges, which differ according to each stage of the process. Many process parameters are measured by sensors set up in various parts of the system. For instance, material temperature, air temperature, oxygen content in the air, air pressure and air flow are continuously monitored and recorded.
To control odours, the air exhausted from the tunnels, mixed with the air flow coming from the areas where waste is mechanically processed, is treated in a largebiofilter. Biofiltration controls odours very efficiently because malodorous gases, absorbed by the superficial moisture of the filter media, are quickly digested through a biological process. The centralized control system also monitors the biofiltration process, which takes place after the air flow has gone through a scrubber. Due to the lack of space in this facility, the biofilter was installed on top of the roof of the composting tunnels.