Bulk Handling Systems (BHS) of Eugene, Oregon — a leading manufacturer of recycling processing equipment — has signed an exclusive licensing agreement with the European company Eggersmann Anlagenbau to design and build high-solids biogas facilities in North America. The Kompoferm® system utilizes a unique anaerobic digestion system that creates energy from organic waste.
The Kompoferm system uses a highly efficient dry fermentation process, with low investment costs and high biogas yields. The system meets the growing demand for more economy and ecology in the burgeoning waste-to-energy industry, says BHS President Steve Miller, adding that the agreement is a perfect complement to BHS’ lineup of recovery systems.
“As we continue to move forward in our efforts to extract more value out of the waste stream, we could not ignore the renewable energy potential available from the organic portion of solid waste,” Miller says. “The Kompoferm system is the leading technology of its type in the world and enables BHS to provide its customers with systems that extract high-value recyclable materials from the waste stream, to make these systems energy neutral, and to provide additional renewable power to the communities where the waste is generated.”
Utilizing a well-controlled, biologically-stable, and proven design, the system’s percolate cycle ensures the production of biogas at a uniformly high level. The special layout shortens the percolate path to a minimum and significantly reduces the area required for the system. Production is continuous, simple, safe and highly-automated.
Several biogas plants in Europe have used the process with excellent success, Miller says, adding that although there are biogas plants operating in North America, the standard technology currently used is not as advanced or efficient as the Kompoferm system. Several projects using the design are already in the planning stages in North America, with the first Kompoferm plant slated to begin operation in 2011 in San Jose, California.
Total system solution
The Kompoferm anaerobic digestion process can be used on its own or combined with the BHS system to create a complete zero waste solution.
In a combined system, municipal waste is brought to a facility where the BHS Bag Breaker releases the contents of bagged material without damaging the commodities and eliminates the need for manual labour to open bags. The Nihot Single Drum Separator further processes the waste using the latest in air technologies to separate by material density. The BHS Polishing Screen has the unique ability to create three material fractions: mixed fibre, containers and organic fines.
Unders from the Polishing Screen are conveyed to a container line for further separation. A cross belt magnet effectively removes ferrous metals from the container stream. Optical sorters use high-speed infrared detection technology and precise colour sensing technology to rapidly identify and separate containers with high efficiency and low product loss.
The BHS Eddy Current Separator uses a strong magnetic field to efficiently and accurately repel aluminum from incoming materials. The patented Debris Roll Screen uses unique disc design and configuration for optimum material agitation and separation and accurately sizes organic material for further processing.
The organic material is prepared for the Kompoferm dry fermentation system and loaded into the digester tunnels and processed in a batch system. At the beginning of the process, oxygen is added to the organic waste to bring the material up to the temperature necessary to begin the dry fermentation process. The exhaust from this initial phase is sent to a bio filter.
Conditioned water, or percolate, is added to the organic material during the fermentation period. Percolate is drained from the digester tunnels and returned to the percolate tank. The percolate goes through a sediment trap for removal of any solids before the liquid continues on to the tank.
The percolate is heated within the tank, creating a methane rich gas. Percolate continues to be added to the biomass in the digester tunnels at specific intervals during the process period of about 21 days. Methane gas is produced during the methanogenic process and is transferred to the percolate tank where it is then combined with the methane gas already in the tank. The mixed methane gas is transported to a storage tank.
The methane gas is transferred from the storage tank to the combined heat and power station to create energy. As the anaerobic digestion process continues, the biomass is reduced in volume and methane production tapers off. Air is added at the end of the process to terminate the methanogenic phase. The exhaust from the termination stage is sent to the bio filter.
At the end of the anaerobic digestion the resulting digestate is ready for further processing. The digestate is transferred into in-vessel composting tunnels where it’s mixed with fresh biomass to further the composting process. Air is added to the digestate mix to initiate the composting process.
The exhaust from the composting tunnels is transferred to an oxidizer where heavy particles are captured before the air continues to the bio filter. The secondary waste is taken to the composting or storage area for maturation.