Anaerobic Digestion

Anaerobic digestion may be a viable manure treatment and handling method for dairy farms. This process produces renewable energy, helps to control water pollution, reduces odors, and reduces the emissions of greenhouse gases. Methane production and then the irrigation of the odorless effluent through irrigation systems during the growing season is a method of manure handling that has a beneficial impact on the environment. These systems combined with a nutrient management plan (NMP) will also improve neighbor relations and will help provide for sustainable development of the dairy industry.

Anaerobic Digestion Basics

  • Anaerobic digestion is the breakdown of complex organic material by microorganisms in the absence of oxygen. The end products are methane, carbon dioxide, some trace gases, and stabilized organic matter.
  • Dairy Manure
  • Food Waste
  • Digestate
  • Methane Gas
  • Benefits of Anaerobic Digestion on Farms
    • Reduction of Greenhouse Gas Emissions
    • Odor Reduction
    • Improvement of Water Quality
    • Generation of Renewable Fuel/Energy
    • Conservation and Utilization of Crop Nutrients
    • Revenue Potential
    • Pathogen Reduction
    • Pre-treatment
    • Co-digestion
  • Successful operation of the system on-farm
  • The economic value of generated power

Anaerobic Digestion General Resources

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Feasibility of Anaerobic Digestion Systems

Before constructing and operating an anaerobic digester, it is best to first ensure that the process is feasible for the farm.

Feasibility Resources

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Centralized Anaerobic Digestion

Centralized Digester Resources

High capital costs are one of the greatest obstacles to installing an anaerobic digester, which this Cornell report found may require at least 850 cows to be financially viable. For farms with fewer cows, it may be possible for two or more farms to share the costs of a “centralized” or community digester. A centralized facility could also be built and operated by an independent party, releasing the dairy operation from the duties of managing the system.

Co-Digestion Resources

Anaerobic digestion (AD) is a biochemical degradation process that converts complex organic materials into biogas in the absence of oxygen. Biogas is composed of methane, carbon dioxide and trace amounts of hydrogen sulfide. Animal wastes, especially dairy manure, have proven to be ideal feedstocks for anaerobic digesters. Food wastes, mostly generated from food processing, food service, and retail establishments, also can be excellent feedstocks for AD. Food wastes typically have high ratios of volatile solids/total solids (VS/TS), which indicate high energy content.

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