A Short History of Anaerobic Digestion

Jan Baptita Van Helmont first determined in the 17th century that flammable gases could evolve from decaying organic matter. Count Alessandro Volta concluded in 1776 that there was a direct correlation between the amount of decaying organic matter and the amount of flammable gas produced. In 1808, Sir Humphry Davy determined that methane was present in the gases produced during the anaerobic digestion (AD) of cattle manure.

The first digestion plant was built at a leper colony in Bombay, India, in 1859.¹ AD reached England in 1895 when biogas was recovered from a "carefully designed" sewage treatment facility and used to fuel street lamps in Exeter.² The development of microbiology as a science led to research by Buswell³ and others in the 1930s to identify anaerobic bacteria and the conditions that promote methane production.

In the world of AD technology, farm-based facilities are perhaps the most common. Six to eight million family-sized, low-technology digesters are used to provide biogas for cooking and lighting fuels with varying degrees of success. In China and India, there is a trend toward using larger, more sophisticated systems with better process control that generate electricity.

In Europe, AD facilities generally have had a good record in treating the spectrum of suitable farm, industrial, and municipal wastes. The process was used quite extensively when energy supplies were reduced during and after World War II. Some AD facilities in Europe have been in operation for decades or even generations. Dramatic growth in the farm digester sector has occurred over the 2000 - 2025 period in countries with favorable rules and incentives. For example, Germany has nearly 10,000 anaerobic digesters, with many of those located on farms.

One of the most dramatic examples of successful large-scale anaerobic digestion facilities has been Denmark, where over 100 large centralized plants are now in operation. In many cases, these facilities co-digest manure, clean organic industrial wastes, and source-separated municipal solid waste (MSW).

Denmark's commitment to AD has resulted in consistent incentives and rules that encourage biogas production.  While the initial focus was on electricity from biogas, the industry has shifted to producing "Renewable Natural Gas" that is pumped into the nation's natural gas pipeline grid.  As of 2026, over 40% of the nation's natural gas use comes from biogas.  One of the key policy tools used to encourage technology deployment is "green pricing," i.e., allowing manufacturers of biogas-generated electricity to sell their product at a premium. Interestingly, the sales of co-generated hot water to specially-built district heating systems are becoming an important source of revenue for project developers.

In the United States, on-farm anaerobic digestion has been in use for over half a century, with some early examples being the McCabe Farm in Iowa and the Mason-Dixon Farm in Pennsylvania, both of which began operation in the 1970s. Odor control was an early driving force behind digester projects, but as electricity generation technology developed and regulations became more favorable, farmers began to experience income from their digesters when the biogas was used to generate electricity and heat. In the 2020s, incentives for "Renewable Natural Gas" led to a rapid build-out of very large farm digesters that purified their biogas and injected it into the natural gas pipeline network. Biogas management companies have also emerged, where the digesters are operated on behalf of the farmer, thus reducing the labor and management tasks associated with anaerobic digestion.

Design simplicity has been identified as a key factor in successful facilities. Other factors influencing success have been local environmental regulations and other policies governing land use and waste disposal. Because of these environmental pressures, many nations have implemented or are considering methods to reduce the environmental impacts of waste disposal.

The use of the AD process for treating industrial wastewater has grown tremendously during the past decade. Worldwide, more than 1,000 vendor-supplied systems now operate or are under construction. It is estimated that European plants comprise 44% of the installed base. Only 14% of the systems are located in North America. A considerable number of the systems are located in South America, primarily Brazil, where they are used to treat the vinasse coproduct from sugarcane-based ethanol production.⁵

Many industries use digesters to treat their waste materials, including processors of chemicals, fiber, food, meat, milk, and pharmaceuticals. Often, they are used as a pretreatment step that lowers sludge disposal costs, controls odors, and reduces the costs of final treatment at a municipal wastewater treatment facility. From the perspective of the municipal facility, pretreatment effectively expands treatment capacity.

Although the first digester to use MSW as a feedstock operated in the United States from 1939 to 1974, it is receiving renewed interest. MSW processing facilities have made significant progress towards commercial use in recent years, with several in operation for more than 15 years. A number of types of systems have been developed; each has its own special benefits.

Processes such as AD and composting offer the only biological route for recycling matter and nutrients from the organic fraction of MSW. Composting is an energy-consuming process, requiring 50–75 kWh of electricity per ton of MSW input. Composting technology for MSW is commercially available and in use, but its further application is limited mainly by environmental aspects and process economics. AD is a net energy-producing process, with around 75–150 kWh of electricity created per ton of MSW input. MSW digestion technology is now being demonstrated and fully commercialized.

MSW digestion poses many technical problems, including an increase in HRT. High-solid digestion (HSD) systems have been developed with the potential to improve the economic performance of MSW systems by reducing digester volume and the parasitic energy required for the AD process. Several alternative HSD designs have been developed that operate with total solids (TS) concentrations greater than 30%. These designs employ either external or internal mixing, using biogas or mechanical stirrers; in general, all HSD systems have equivalent performance.

1. Meynell, P-J. (1976). Methane: Planning a Digester. New York: Schocken Books. pp. 3.
2. McCabe, J.; Eckenfelder, W., eds. (1957). Biological Treatment of Sewage and Industrial Wastes. Two volumes. New York: Reinbold Publishing.
3. Buswell, A.M.; Hatfield, W.D. (1936). Bulletin 32, Anaerobic Fermentations. Urbana, IL: State of Illinois Department of Registration and Education.
4. Danish Ministry of Energy and Environment (1996). Energy 21; The Danish Government's Action Plan for Energy 1996. Copenhagen, Denmark.
5. Lettinga, G.; Van Haandel, A. (1992). "Anaerobic Digestion for Energy Production and Environmental Protection." Chapter 19 in Renewable Energy: Sources for Fuels and Electricity. Covelo, CA: Island Press. pp. 817-839.

Reproduced with permission from Methane Recovery from Animal Manures: The Current Opportunities Casebook(PDF).  Revised and updated 2026.