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Monday, December 17, 2012

Municipal Solid Waste Management In Developing Countries (Part V)

<<<Read Part IV

Health, Environmental Impact and Reasons for MSWM in Developing Countries

Assessing the impacts of municipal solid waste management involves consideration of a large number of components. Health impacts include exposure to toxic chemicals through air, water and soil media; exposure to infection and biological contaminants; stress related to odor, noise, vermin and visual amenity; risk of fires, explosions, and subsidence; spills, accidents and transport emissions.
  • Opening dumping:

Fires should not be tolerated because of the health impacts of inhaling smoke, particularly the toxic dioxin and furans gases generated by the burning of certain plastics. The decomposing wastes produce noxious liquid, known as leachate, especially during rainy seasons. This leachate flows into streams and groundwater resources, contaminating water supplies. Scavenging at the dumpsite is a hazardous occupation for the waste pickers, particularly where dangerous medical wastes (such as blades and items with needles) are mixed with the general municipal wastes.
  • Sanitary Landfilling

Health and social impacts include odor nuisance; ozone formation that can cause pulmonary and central nervous system damage; fire and explosion hazards from build-up of methane; an increase in the number of  disease vectors (birds, rodents and insects); and ground and air pollution from leachate and landfill gases. Water contamination by leachate can transmit bacteria and diseases. Typhoid fever is a common problem for the people of developing nations because many of them cannot afford to dig wells deep enough to reach fresh aquifers.    There are also many environmental impacts of landfills. Ozone formation can cause decreases in crop yield and plant growth rate. Methane and carbon dioxide are greenhouse gases that contribute to global warming.
  • Incineration:

Incineration impacts society by production of odors. The most important health and environmental impact is from air emissions, which include particulates, CO, NO2, acid gases (chlorides and sulfides), volatile organics and mercury. These compounds contribute to bioaccumulation of toxics and acid rain. Inhalation of particulate matter poses a health danger.
  • Composting/Anaerobic Digestion

Health and social impacts include noise, odor, and unsightliness. Additionally, many of the microorganisms found in compost are known respiratory sensitizers that can cause a range of respiratory symptoms including allergic rhinitis, asthma, and chronic bronchitis. Composting is aerobic and produces primarily carbon dioxide, while anaerobic digestion produces methane. Both gases contribute to global warming.
  • Other risks

Recycling can also pose health and environmental risks. Sorting facilities contain high concentrations of dust, bioaerosols and metals. Workers commonly experience itching eyes, sore throats, and respiratory disease. Environmentally speaking, recycling uses a large amount of energy resources. For people in developing countries, bodily wellbeing is a far more pressing concern than the facts that open burning of garbage contributes to acid rain or global warming. Outrage over health issues of poor waste management could therefore be a motivating factor towards more sustainable environmental practices.

Reasons for Municipal Solid Waste Management/ Problem of Municipal Solid Waste

Notwithstanding the many challenges associated with the above approaches to municipal waste management, a key question is why at all this is important. Solid waste management is critical in mitigating risks to public safety, as well as in the prevention of environmental degradation. Waste is a serious environmental and health hazard and lead to the spread of infectious diseases. These broad threats are deemed to be the key reasons for effective municipal solid waste management:
  • Disease vectors:

Municipal solid waste disposed improperly provides the perfect environment for the breeding of rodents, flies and other vermin. Although detritivores (organisms that feed on and break down dead plant or animal matter, returning essential nutrients to the ecosystem. They include micro-organisms such as bacteria, as well as larger organisms such as fungi, insects, and worms)  are essential organisms for breaking down complex organic materials in the decomposition process, it is important to manage their population since they contribute to the spread of several related diseases.
  • Explosive gases

As garbage in landfills undergoes microbial decay and other chemical reactions, landfill gas is produced. Depending on the waste composition and the structure of the landfill, this gas builds up pressure under the surface, thereby creating a high incidence of fires and release of toxic fumes. Landfill gas also has traces of nitrogen, oxygen, water vapour, sulphur and other contaminants. It is for this reason that solid waste management should be well designed, with adequate systems for the monitoring and control of the emission of landfill gases.
  • Air pollution and other environmental nuisances

Normally it is the wet waste that decomposes and releases a bad odour. This leads to unhygienic conditions and thereby causes rise in the health problems. Other than this, co-disposal of industrial/ residential hazardous waste with municipal waste can expose people to chemical and radioactive hazards. The generation of toxic emissions may also be a key contributor to public health risks, and should be controlled as part of the overall municipal waste management effort.
  • Landfill gas migration

Gases are extremely mobile once there is nothing to constrain their movement from an area of high concentration to an area of low concentration. Landfill gas may therefore migrate to areas in close proximity to landfill sites, thereby creating potential health hazards such as respiratory diseases, or even explosive conditions. Moreover, landfill gases are a significant contributor to greenhouse gas emissions with related implications for their contribution to global climate change. This issue is developed further below.
  • Leachate generation/ Surface and ground water pollution

Leachate is produced when rainwater percolates with liquids created from decomposing waste in an anaerobic environment. It has the potential to travel through the soil layers to the water table, ultimately contaminating groundwater resources which, in turn, contribute to land-based sources of pollution to the marine environment. Leachate consists of aromatic hydrocarbons (benzene and toluene), chlorinated benzenes, volatile halocarbons, phenols, and various carboxylic acids. These contaminants may cause major public health risks to exposed populations.
  • Global waste management and climate change

The approach to waste management around the globe also has a significant impact on global warming and climate change. This is because a number of waste disposal methods are themselves significant producers of greenhouse gases (GHGs) which have been identified as the cause of global warming. While contemporary thinking on global warming focuses on carbon dioxide (CO2) as the main offender, other GHGs such as methane (CH4), water vapour (H2O), and nitrous oxide (N2O) are certainly more important drivers of global warming from a waste management point of view. It has noted that global waste production was predicted to double over the next 20 years, driven by increased urbanization and greater waste generation per capita in emerging economies. This overall increase in the generation of municipal solid waste globally, along with evolving waste management strategies, particularly in developing countries, holds the potential to exacerbate the climate change challenge which confronts humanity over the medium to long term.

References

  1. Allende, R., 2009. Waste history in the Gambia. Thesis (MSC). University of the Gambia.
  2. Kanat G, Demir A, Ozkaya B, Bilgili MS (2006). Addressing the operational problems in a composting and recycling plant. Waste Manage., 26: 1384-1391.
  3. Haque A, Mujitaba IM, Bell JNB (2000). A simple model for complex waste recycling scenarios in developing economies. Waste Manage., 20: 625-631.
  4. Nunan F (2000). Urban organic waste markets: Responding to change in Hubli-Dharwad, India. Habitat Int., 24(3): 347-360.
  5. Schubeler, P., 1996. UNDP/UNCHS (Habitat)/World Bank/SDC Collaborative Programme on Municipal Solid Waste management in Low-Income Countries. Urban management and Infrastructure. Conceptual Framework for Municipal Solid Waste Management in Low-Income Countries. Working Paper No. 9. Available from http://science.jrank.org/pages/7297/Waste-Management.htm
  6. UN-HABITAT (United Nations Settlements Programme) (2010), “Urban Trends: Urbanization and Economic Growth” UNHABITAT, Kenya.

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