Municipal Solid Waste Management In Developing Countries (Part V)

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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.

Municipal Solid Waste Management In Developing Countries (Part IV)

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Processes or Stages of Municipal Solid Waste Management

Municipal solid waste management comprises various stages from the generation of waste to its final disposal. Planning for proper management must consider all these stages. For a complete system of solid waste, all the stages need to be in place:

1.     Storage System

Keeping the waste in containers is hygienic, and minimises handling and loading times, but under some economic conditions it appears that less satisfactory collection systems, that deposit waste on the ground and then load it, cost less per ton. Containers can be a very significant part of the costs of a collection system, particularly if the containers quickly become corroded or damaged or need to be replaced frequently for other reasons. Solid waste storage facilities for domestic wastes may be classified as household (that is, household bins or bags, sometimes known as primary storage) and community (that is, containers or bunkers, each used by many households, known as secondary storage).

 2.     Collection of Municipal Solid Waste

The term “solid waste collection” is taken to include the initial storage of waste at the household, shop or business premises, the loading, unloading and transfer of waste, and all stages of transporting the waste until it reaches its final destination disposal site (the sweeping of streets and public places, the cleaning of open storm drains and the removal of these wastes are also included). This destination may be a material processing facility, a transfer station or a landfill, a treatment plant or disposal site. Collection of generated solid waste is the crucial part in MSW management                                                                                              
Stages of municipal solid waste collection include: collection from various non-point sources and point sources and transportation to disposal sites.

3.     Transfer System

The requirements of a vehicle for collecting wastes are very different from the requirements for transporting the wastes that it has collected to a transfer station, disposal site or processing plant. For collecting, the vehicle should be small, easy to maneuver along narrow streets. For transporting the wastes to the disposal site a large vehicle is required with a higher-powered engine for fast travel.
Conventional split level transfer stations normally have ramps which the primary collection vehicles drive up to discharge their loads, either directly into containers or secondary transport vehicles below  or into stationary compactors which compact the waste into hook lift containers or truck bodies.

4.     Recycling and Resource Recovery and Treatment of Solid Waste

The stages involved in recycling may include picking, transporting, trading, sorting, cleaning and processing. In some cases manufacturing may also be involved. Reuse of items for the same purpose as that for which they were originally used (such as drink bottles) is included. To these activities is added the recovery of energy from wastes for economic purposes. The term “resource recovery” is strictly more accurate, but less well-known. The treatment of solid wastes includes any processes that are implemented to reduce the costs of transporting or disposing of wastes, and any processes that reduce the risks posed by the wastes. There are clear overlaps with recycling.
Composting can be regarded as recycling when there is a market for the product and as treatment when the purpose is to reduce the pollution arising from the disposal stage. Incineration is generally regarded as treatment, but can be considered as a resource recovery process when energy from the burning of the waste is put to economic use.
• Composting: is the converting, by aerobic bacteria, of biodegradable wastes (such as food waste) into a good soil conditioner. Another benefit of composting is that it reduces the amount of biodegradable wastes in the waste stream, resulting in less pollution. In general, mechanised composting has not proved sustainable in developing countries due to the high costs and short life of the equipment, as well as the problems of finding a market for the compost large enough to justify a mechanised operation. However, small-scale manual composting of selected wastes (typically market and abattoir wastes) can be viable.
Composting and anaerobic digestion uses natural microbial organisms to decompose the organic fraction of MSW. These methods reduce the volume of waste that must be landfilled or incinerated, and end products can potentially be used as agricultural fertilizers, or processed into fuels for motor vehicles. However, like incineration, project implementation can be too expensive for poor communities.         
• Incineration: is the high-temperature combustion of wastes. Noncombustible must be sorted out before incineration. Benefits of incineration include reduction of volume of waste and production of energy in the form of electricity and heat. Inadequately designed and poorly operated incinerators can cause dangerous air pollution. Incinerators are used for municipal wastes and for selected hazardous wastes. However, construction and start-up costs of incineration facilities can be prohibitively expensive for developing nations.

5.     Final Disposal

Final disposal is the last stage in the waste management stream. This is the stage when all the collected waste requires a safe disposal. Despite all the efforts to reduce, recycle and reuse the waste, there are always certain quantities of waste requiring final disposal. At the final disposal stage we need to deal with the larger and accumulated quantities of waste.                                                                         
The two most common methods of municipal solid waste disposal are open dumping and sanitary landfilling. Incineration, composting and anaerobic digestion are volume reducing technologies; ultimately, residues from these methods must be landfilled. 

• Open or Crude Dumping: waste is dumped at a designated site without any environmental control measures. This is not a disposal option but a common practice in developing countries. It has high environmental health risks. Waste is unloaded wherever the driver of the collection truck finds a convenient space. Access to parts of the site may be blocked by piles of waste, accumulations of water or rough terrain. Usually there are many smoldering small fires. These fires may be started by waste pickers for various reasons or by municipal employees in an attempt to discourage fly breeding and reduce the volume of the waste. Neighbouring householders may light fires to control the insects and rats. Some fires may also start as the result of natural processes, scraps of glass focusing the sun’s rays, or the depositing of burning loads. 
• Sanitary Landfilling: landfilling is the only true “disposal” method of managing MSW. It is also the most economical, especially in developing countries where it typically involves pitching refuse into a depression or closed mining site. Landfills produce landfill gases and leachate which can harm human and natural systems. Landfill gases (LFGs), produced when methanogens decompose complex molecules, are primarily methane and carbon dioxide (up to 90%), but also include CO, N2, alcohols, hydrocarbons, organosulfur compounds, and heavy metals.

Leachate forms as water percolates intermittently through the refuse pile, and can contain high levels of nutrients (nitrogen, phosphorous, potassium), heavy metals, toxins such as cyanide, and dissolved organics.
The objective of sanitary landfilling is to dispose of solid waste in a way that causes minimum impact on the environment, and at minimum cost. In order for the operation to be economical, the site must be well managed so that the maximum amount of waste can be placed on the site. Sanitary landfills can be used to fill holes below ground level or form hills higher than the surrounding ground. Intermediate stages between crude dumping and full sanitary landfilling are called controlled dumping or managed (or engineered) landfilling.

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Municipal Solid Waste Management In Developing Countries (Part III)

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Municipal Solid Waste Management (MSWM) In Developing Countries      

Proper management of municipal solid waste is critical to the health and well-being of urban residents (World Bank 2003). Municipal solid waste (MSW) management is a major problem in most developing countries. In developing countries, several tons of municipal solid waste is left uncollected on the streets each day, clogging drains, creating feeding ground for pests that spread disease, causing water pollution, land contamination, environmental degradation and creating a myriad of related health and infrastructural problems. The primary target of MSWM is to protect the health of the population, promote environmental quality, develop sustainability, and provide support to economic productivity. Although in developing countries the quantity of solid waste generated in urban areas is low compared to industrialized countries, the MSWM still remains inadequate. 

Municipal Solid Waste Management (MSWM) problems in developing countries have become more pronounced in recent years, as a result of inadequate collection and disposal of wastes. In most cities, wastes are not properly collected and where proper collection is ensured, only a small fraction receives proper disposals (Ayininuola and Muibi 2008). As such, the need to develop alternative methods of managing municipal solid wastes (MSW) such as composting, separation, and recycling have been used adeptly to meet these growing concerns (Haque et al., 2000; Kanat et al., 2006; Nunan, 2000). Despite such alternative methods, however; situations within countries vary due to different parameters which may cause certain effects on such activities; thereby causing more difficulties or complexities which may expand the extent to which these concerns are to be addressed. 

Factors Affecting Proper Municipal Solid Waste Management in Developing Countries

Municipal solid waste management (MSWM) is an ‘important entry point for integrated urban management support (Schubeler 1996)’. More specifically, it refers to that part of the waste stream that is collected by, or on behalf of, local authorities. Factors affecting proper municipal solid waste management processes or stages include:

• Accelerated growth of urban population with unplanned urbanization.
• Increasing economic activities and lack of training in modern solid waste management practices in developing countries complicates the efforts to improve solid waste services.
• The changes in consumption patterns with alterations in the waste characteristics have also resulted in a quantum jump in solid waste generation. 
•  Recent studies has shown that a substantial part of the urban residents in the old city and suburban informal settlements of developing countries have little or no access to solid waste collection services. This is due to lack of proper land use planning which resulted in the creation of informal settlements with narrow streets that make it difficult for collection trucks to reach many areas. The result is that a large portion of the population is left without access to solid waste management making them particularly vulnerable.
•  In addition, solid waste management is hampered by a lack of data at all levels from the ward, district and municipality, and where available, is generally unreliable, scattered and unorganized. As a result, planning of solid waste management has remained a difficult task.

Municipal Solid Waste varies in composition (it may include paper, food, which may be influenced by many factors, such as culture affluence, consumption pattern, location etc. Municipal Solid Waste Management depends on the characteristic of the solid waste including the gross composition, moisture contents, average particle size, chemical composition and density, in which knowledge of these usually helps in disposal plans, selection of the most appropriate technology for a proper and sustainable MSWM. This has been discussed in PART I under the composition of municipal solid waste generation.

      

                                                                                 

          

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