Anaerobic Digestion of Animal Manures: Understanding the Basic Processes
Organic Compounds Breaking Down into Biogas
The process of producing methane from manure is fairly straight forward – seal manure in an airtight container at a favorable temperature and it will break down into biogas: a mixture of Methane (CH4), Carbon dioxide (CO2), and trace amounts of other gases.…
When manure is anaerobically digested, the biogas produced is primarily composed of methane and carbon dioxide, with lesser amounts of hydrogen sulfide, ammonia, and other gases. Each of these gases has safety issues. Overall, biogas risks include explosion, asphyxiation, disease, and hydrogen sulfide poisoning.…
Biogas generated from anaerobic digestion processes is a clean and environmentally friendly renewable fuel. But it is important to clean, or upgrade, biogas before using it to increase its heating value and to make it useable in some gas appliances such as engines and boilers.
While most large farms use their biogas for heat and power, it is worthwhile to consider all the options before deciding which path to take, including direct sale of biogas to an off-farm buyer.…
Anaerobic Digestate Pile, Scenic View Dairy, MI. Photo: M.C. Gould, MSU Extension
Anaerobic digestion generates a wide range of byproducts that farmers can use in their farming operations or sell. Beyond biogas used to generate electricity or as fuel, and liquids used for fertilizer or soil amendments, there are solid byproducts, which have a wide range of applications.…
The manure handling system of any farm is made up of many different components, each with a different function and purpose. An anaerobic digester, although only one component of the system, can greatly improve the environmental performance and efficiency of the overall system. The main effect of anaerobic digestion is conversion of organic matter to biogas.…
Benefits of Anaerobic Digestion of Manure in Reducing Pathogens
Manure is a biologically active material that hosts and supports many microorganisms and thus can seldom be considered “pathogen free.” Certain manure handling techniques and methods, however, can limit the production and multiplication of such pathogens.…
All anaerobic digesters perform the same basic function. They hold manure in the absence of oxygen and maintain the proper conditions for methane forming microorganisms to grow. There is a wide variety of anaerobic digesters, each performing this basic function in a subtly different way.…
Anaerobic digestion of manure and other feedstocks produces biogas which can be burner to make energy on farms. Learn how to evaluate a feedstock and which ones to exclude for biogas production.
|Anaerobic Digester in Charlotte, VT. Photo: Caragh Fitzgerald, University of Maine.
A great variety of organic material can be used in anaerobic digesters as a feedstock for generating biogas.…
Harnessing energy from livestock waste.
Intro | Feedstocks | Processing | Utilization
On-farm biogas production has long been a topic of interest for farmers, with historical records of biogas production going back several hundreds of years. In modern livestock production systems, for example, the benefits of producing biogas are significant and include:
- provision of supplemental renewable energy
- odor reduction
- reduction of emissions of greenhouse gases
- pathogen control
- waste biostabilization
- nutrients are preserved and transformed into plant-available forms
The economics of biogas production, however, are sometimes difficult to justify unless the accompanying environmental benefits and other by-products are considered.…