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China: A Leader in Biogas Energy & Productive Peri-Urban Agriculture
The image above depicts pools of wastewater at an animal waste recycling facility one hour from Beijing at an agricultural cooperative in China. Beautiful? Perhaps not; but while it may not be much to look at, facilities like these can be used to produce renewable biogas, organic fertilizer, and reduce pollution. China is an emerging leader in the construction of environmentally efficient and economically practical waste-recycling systems. Animal waste products contain valuable nutrients that can be recycled back into the soil and contain methane gas that can be harvested as “biogas” for energy use. While animal wastes can be hazardous to the environment and can find their way into rivers and other fragile ecosystems, these same wastes can also be harvested and reused in an environmentally friendly fashion.
According to an article from ecotippingpoints.org, there are over 30 million households in China that have anaerobic “biogas digesters.” These digesters encourage the growth of anaerobic microorganisms in sealed pools to ferment organic waste, releasing combustible gases high in methane (biogas). These digesters often pay for themselves very quickly, and by some estimates can make back the cost of construction in just over a year of use. These digesters were first promoted on a large scale during the late 60s and early 70s, before the period of opening and reform. After a brief decline following the breakup of the collectivized system of agriculture, the small, affordable digesters have had a dramatic comeback in the last 15 years.
The biogas released by these digesters has many environmental benefits. Undigested manure compost releases methane gas that goes uncollected and unused. Using this renewable energy that would be wasted helps reduce the need to purchase more, likely nonrenewable fuels. Anaerobic digesters also release less methane gas than compost sitting in the field. Methane gas has 22 times the warming effect as CO2, and so reducing the release of this gas can have great benefits towards mitigating global warming.
While anaerobic digesters can be used to harvest energy from animal waste, systems in China are also implemented to manage and recycle waste nutrients. According to the Beijing Academy of Agricultural Sciences, Beijing releases an annual 1,396,000 tons of hazardous animal waste into the environment. This waste is filled with valuable nutrient resources that are productive when used as fertilizer but potentially hazardous if unfiltered and released into fragile ecosystems. The nutrients and water in the waste material can be recycled efficiently and simply by filtering out solids from wastewater in successive steps. At the end of the process, both the filtered water and recovered nutrient fertilizer can be used for growing crops. Ideally a drip irrigation system can be used to make this process as efficient as possible. The Beijing Academy of Sciences notes that if a drip irrigation system is not possible, it is relatively easy to build an alternate and simple piping system. Anaerobic digesters and waste nutrient recycling can be utilized to a much larger extent in China as well as other suitable locations worldwide to have economic and environmental benefits.