Landfilling is a technique for the final disposal of solid waste into soil, which causes neither nuisance nor public health or safety hazards; it is not environmentally harmful either during operation or after close-out. Landfills use engineering techniques to confine solid waste in the smallest area possible, covering them with soil and compacting them regularly to reduce the volume. Additionally, potential problems that could emerge from fluids and gases produced in the landfill from the decomposition of organic matter are anticipated (IBAM, 2006).
Although the estimated mean coverage of USW in Latin America and the Caribbean is 85%, with marked differences between countries, there is no infrastructure for the safe and proper disposal of a large amount of USW (OPS, 2005; IBAM, 2006). In this region, the coverage of USW final disposal in landfills is only 23%, evidencing a serious environmental and health issue resulting from the proliferation of open dumps or USW disposal in water bodies (OPS, 2005). This means that some 236 000 tons are being indiscriminately dumped into the environment, or, in the best cases, in poorly controlled dump sites (OPS, 2005; IBAM, 2006).
The indicator Landfills shows the response of local governments to address USW management. This indicator is not found in other initiatives; the EU splits it into the amount of waste that is disposed of in landfills, incinerated or recycled. The OECD and the UN Commission on Sustainable Development use the expenditure on waste management or disposal; however, adequate information for including this indicator for Mexico is not yet available.
Urban Solid Waste recycling
Recycling involves the physical, chemical or biological processing of waste for using it as raw material in the manufacture of new products. Environmental benefits of recycling include the reduction of municipal waste, lower contamination levels and a reduced use of natural resources (OPS, 2005). Moreover, benefits derived from urban solid waste minimization by the recycling and reuse of materials (that is, the use of waste materials without major modification for their use in the same products as originally intended) directly affect the duration and efficiency of landfills, mainly by reducing the volume of waste that require disposal.
Discrimination of urban solid waste into its organic (food, mainly) and inorganic components (paper, cardboard, textiles, plastics, glass and metal) facilitates its reuse and recycling, reducing both, the pressure to have suitable disposal sites, and the environmental and health impacts associated with inadequate disposal sites (EPA, 1999; Semarnat-INE, 2001; IBAM, 2006). The indicator USW recycling shows the social response and allows the assessment of strategies in this area. Indicators related to reuse and recycling are common in lists of environmental and sustainable development indicators, particularly in those on Sustainable Development of the UN Commission on Sustainable Development, the OECD and the EU.