SWM and Climate Change
The waste sector is an important source of greenhouse gas emissions. According to recent national estimates this sector produces on average 2.4 per cent of national greenhouse gas emissions (UNFCCC, 2005). Solid waste disposal and wastewater are significant sources of methane (CH4). They are estimated to contribute about one fifth of global anthropogenic methane emissions (IEA, 2005).
Landfills and open dumps are the dominant waste disposal options worldwide. In managed and unmanaged landfills, anaerobic degradation of organic material occurs, causing CH4 emissions. Landfill gas (LFG) is about 50.60% methane with the remainder CO2 and traces of non-methane volatile organics, halogenated organics and other compounds (IPCC, 2006; IPCC, 2001b). Incineration and open burning of waste containing fossil carbon are the most important sources of CO2 emissions in the waste sector.
Integrated Waste Management, or IWM, is a tool to determine the most energy-efficient, least-polluting ways to deal with the various components and items of a community's solid waste stream. The IWM hierarchy is based upon the material and energy that is embodied in solid waste and that is associated with its recycling and disposal. The twin goals of IWM are to:
(1) retain as much as possible of that energy and those materials in a useful state , and
(2) avoid releasing that energy or matter into the environment as a pollutant .
Integrated waste management sets up a hierarchy of approaches and technologies for managing solid waste in order to meet these goals. Generally, the farther "up" the hierarchy from which the technology is chosen, the more benefits in efficiency and retained economic value. The very highest option in the hierarchy is, don't create the solid waste in the first place, and is termed “source reduction.” Source reduction can be done in several ways: • Manufacturing processes can be devised which create fewer or less toxic waste by- products; • Consumers can choose not to purchase products with excessive packaging; or • Consumers can choose not to purchase products which are unnecessary "luxuries," which require unjustifiably large amounts of energy or natural resources to manufacture, or which cause toxic waste problems in manufacture, use, or disposal.
The other higher level IWM options are (in order): Reuse -- The use of a product more than once in its same form for the same or similar purpose. Recycling -- The process by which materials otherwise destined for disposal are collected, processed, remanufactured into the same or different product, and purchased as new products. Composting -- The controlled process whereby organic materials are biologically broken down and converted into a stabilized humus material. Materials retain their value for longer periods of time if they are handled within these “top four” levels of the IWM hierarchy.