Organic Waste

Hazards

There are number of factors that make the management of organic waste difficult. Organic waste tends to attract pests and cause odor problems. Due to its high water content, organic waste is not suitable for storage or long transportation. The most notable characteristic of organic waste is that it undergoes a relatively active biodegradation process. This biodegradation results in pollution of the surrounding environment. When a large amount of organic waste is introduced into water, oxygen is depleted and fish may die. Organic waste can also be a source of air pollution. If the decomposition of organic waste takes place under anaerobic conditions, such as occurs within landfills, the decomposition [Page 636]process produces polluting by-products. The most prevalent of these is methane, a greenhouse gas 25 times more potent than carbon dioxide. Due to its origin, organic waste, especially human and animal waste, can contain pathogens, parasites, and other forms of pollutants. The direct disposal of organic waste to land and waterways has been a common practice throughout human history. This leads to the spread of commutable disease, which takes the life of a child every 20 seconds in the early 21st century. Some scholars are concerned that the repeated application of organic waste on land will lead to an accumulation of heavy metals in the soil and further contaminate agricultural products. Organic waste also contains high level of nutrients, such as phosphorous and nitrogen. The improper disposal of organic waste can cause the eutrophication of lakes and further impair water quality. The careful management and disposal of organic waste is necessary for protecting the health of the public and of ecosystems.

Definition

There is no set definition for organic waste, but a subset of organic wastes is defined by regulation. The European Union (EU) established the Landfill Directive in 1999 in order to reduce the content of biodegradables at landfills and to reduce landfill methane gas emissions, a major human-induced methane emissions source. The Landfill Directive defines biodegradable waste as “waste that is capable of undergoing anaerobic or aerobic decomposition, such as food and green waste, and paper and paperboard.” Biowaste is also a term used in regulations for solid waste management in Europe, which indicates the combination of food and yard waste.

Treatment

Source separated organics or organic fraction of municipal solid waste are operationally defined terms commonly used for municipal waste management. Alternative to direct disposal, organic waste can be treated by incineration, composting, anaerobic digestion, or by mechanical biological treatment both aerobically and anaerobically. Through these treatments, organic waste is stabilized. Such treatment also results in the reduction of volume and disinfection of the waste, making its final disposal easier and safer. Some treatment processes are more suitable for certain fractions of organic waste. For example, some paper waste cannot be handled by the composting process but does not impose any difficulties for incineration. Thus, the fractions of waste included in source separated organics or the organic fraction of municipal solid waste is highly dependent on which technologies and management schemes are adopted in a given location.

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