High Solids Digester: Dry Fermentation

BIOFerm™ Dry Fermentation Digester

BIOFerm™ Dry Fermentation technology differs from traditional “wet digester” tank systems that utilize liquid feedstock and physically stir and agitate materials with moving parts.

Our BIOFerm™ Dry Fermentation (aka high-solids) technology uses a batch-style approach where waste material remains stationary during anaerobic digestion, requiring no internal moving parts. These attributes allow our Dry Fermentation digester to recover energy from almost any kind of organic waste.

BIOFerm Dry FermentationThe system is comprised of individual rectangular fermentation chambers (each with 114’ x 23’ x 17’ dimensions) where the biomass is loaded by a front-end loader and remains for ~28 days. Modular construction design allows the system to be scaled according to the amount of organic material available at the particular operation, with annual waste streams starting at ~8,000 tons and up.

BIOFerm™ Dry Fermentation is best suited for operations that process organic waste with a total solids content greater than 25%, including:

  • Food waste
  • Yard clippings
  • Dry manure on bedding
  • Other high-solids waste

Biogas produced is collected inside a flexible gas storage bag and is then continuously fed to the biogas utilization source. Biogas can be either used in a combined heat and power (CHP) unit to generate electricity and heat, or upgraded to renewable natural gas (RNG) for gas grid injection and vehicle fuel as compressed natural gas (CNG).

A case study of the BIOFerm Dry Fermentation system processing food and yard waste at the University of Wisconsin – Oshkosh can be accessed here.

Advantages of BIOFerm™ Dry Fermentation

  • Well suited to process municipal organic waste
  • Integrates well into composting operations
  • Virtually immune to physical contaminants as the input material remains stationary and does not come into contact with any moving equipment inside fermentation chambers
  • Batch process is more stable than a continuously fed complete mix system; if  bacteria in one fermentation chamber are out of balance/underperforming, it is less devastating to the system as a whole than other anaerobic digestion systems and the affected chamber can be quickly remediated by exchanging the substrate

Safety and Plant Monitoring

All BIOFerm™ biogas systems are constructed with the highest degree of safety in mind. Standard safety installments include: fire and explosion protection, pollution control, ventilation, biofilters, noise prevention, ground water certification, and lightning deterrents.

All functions of the plant are monitored through the automated plant control system. The software continuously keeps a log of all data points and displays an easy-to-read plant schematic. This allows the operator to oversee the plant operation, biogas production and possible malfunctions.

Continuous monitoring of conditions inside each fermenter is an integral safety measure. By checking and evaluating aspects such as methane, carbon dioxide and hydrogen sulfide levels, a plant operator is instantly alerted if a problem arises. Plants can be shut down via automated controls so that any irregularity can be fixed.

 

 

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