Anaerobic Digestion
The foundation of BioStar's technology is anaerobic digestion (AD); the decomposition of organic materials as a product of bacterial metabolism in an environment absent of oxygen. Almost any organic material can be processed with anaerobic digestion. This includes biodegradable waste materials such as waste paper, grass clippings, food, sewage and animal waste. AD reduces the emission of greenhouse gas es into the atmosphere and is widely used as a renewable energy source. The process produces methane -rich biogas suitable for energy production to offset the use of fossil fuel energy power. Additionally, the nutrient-rich digestate (stabilized solids) recovered from the process can be used to produce environmentally-friendly organic fertilizer.
AD dates back as far as the 10th century when the Assyrians used it to heat bath water. It was historically insignificant before reappearing in 17th century Europe , when it was determined that decaying organic matter produced flammable gases; again it used to heat water. The first large scale application was in the 1890's when the city of Exeter , UK used AD to treat wastewater and produce biogas for fueling city streetlamps. From there it continued to be used as a way to stabilize sewage sludge. The first AD systems were large, unheated and unmixed tanks with significant operational problems which limited widespread adoption of the technology until the twentieth century.
The development of the field of microbiology in the 1930's allowed scientists to determine that the mechanism of gas production depended on anaerobic bacteria. Subsequent experiments were carried out to determine the optimal environmental conditions for gas production. As a result, heated and mixed digesters of increasing complexity came to the market in the middle of the twentieth century in Europe . The first commercial applications were on farms where manure was digested to produce heat and electricity. As the knowledge base expanded, AD was employed to treat other farm wastes, wastewater, industrial organics, and Municipal Solid Waste ( MSW ). The energy crises in the 1970s prompted American research into alternative energy strategies, and AD was one such option. This push resulted in the first farm digester built in America in 1970 where the biogas could be used for heat and power. At present, development continues on farms as well as wastewater treatment plants, where anaerobic processes and subsequent gas recovery are an industrially-mature technology.
Recent developments in AD technology worldwide are in the treatment of industrial wastes and wastewater. Companies benefit by using the biogas produced, reducing odor and the volume of sludge produced, as well as sanitizing the wastes. Germany and Denmark , where environmental legislation concerning waste disposal is stringent, lead the way. Although some private industrial facilities in the United States do choose to treat industrial effluent using AD, its application is not as widespread as in most other developed world countries.
The use of anaerobic digestion is widespread in Europe with over 3,000 facilities currently in operation. The use of anaerobic digestion in the United States is in the beginning stages. Anaerobic digestion is particularly suited to wet organic material and is used for effluent and sewage treatment. Anaerobic digestion is a simple process that can greatly reduce the amount of organic matter which might otherwise be destined to be land filled, or burnt in an incinerator, or worse yet, flow into the watershed and into our lakes and streams
Methane and power produced in anaerobic digestion facilities can be used to replace energy derived from fossil fuels, and hence reduce emissions of greenhouse gases. This is due to the fact that the carbon in biodegradable material is part of a carbon cycle. The carbon released into the atmosphere from the combustion of biogas has been removed by plants in order for them to grow in the recent past. This can have occurred within the last decade, but more typically within the last growing season. If the plants are re-grown, taking the carbon out of the atmosphere once more, the system will be carbon neutral. This contrasts to carbon in fossil fuels that have been sequestered in the earth for many millions of years, the combustion of which increases the overall levels of carbon dioxide in the atmosphere.