This article has been divided into parts to cover the need for sustainable management of municipal solid waste in developing countries
Waste was an early problem of mankind, and a growing one that is of major concern to every nation of the world (Allende 2009). In early pre-industrial times, waste generation was not an issue as populations were smaller. Waste was disposed of in the ground where it would turn to compost to improve soil fertility. Now are days, due to population growth and urbanization, the disposal of waste has proved to be a major public health issue and a vital factor affecting the quality of the environment. This, especially in developing countries has become one of the most intractable environmental problems today. Municipal Solid Waste disposal is now a particularly worrying issue that can be likened to a ‘monster’ staring the authorities in the face. Due to increase in population and illiteracy in developing countries, it is difficult to manage waste generation. Most of the manforce in the governing body is utilized in providing basic services like water, health etc. Waste management particularly generation becomes least priority issue. Unauthorized structures, small shops, construction activities, local markets generate huge solid waste. Local bodies most of the times does not have budgetary support to handle waste generation in better manner. Manforce dealing with waste generation is not equipped enough. Trained, motivated working staff always contributes better in minimizing waste generation.
Wastes: are substances, materials or objects discarded as worthless or unwanted, defective, of no further value for human economic production activities or process (Adegoke, 1990).
Solid wastes: are man’s unwanted materials which are non-liquid and non-gaseous and consist of organic matter (easily biodegradable) and inorganic (non-biodegradable which include metals, plastics, bottles and broken glasses).
Municipal Solid Wastes (MSW): include waste from households, businesses and institutions, construction and demolition waste in small quantities, general solid wastes from hospitals (excluding hazardous wastes), waste from smaller industries that is not classified as hazardous, and wastes from streets, public areas and open drains. It is not concerned with wastes from agriculture, larger industries or the mining industries which normally handle their own wastes. Such wastes are generated in huge quantities in many countries, but the systems for collecting, treating and disposing of them are separate from the systems used for municipal solid waste. They commonly called “trash” or “garbage”, include wastes such as durable goods, e.g., tires, furniture; nondurable goods, e.g., newspapers, plastic plates/cups; containers and packaging, e.g., milk cartons, plastic wrap; and other wastes, e.g.,yard waste, food.
Semisolid wastes such as sludge and nightsoil are considered to be the responsibility of liquid waste management systems. While hazardous industrial and medical wastes are, by definition, not components of municipal solid waste, they are normally quite difficult to separate from municipal solid waste, particularly when their sources are small and scattered. Municipal solid waste management systems should therefore include special measures for preventing hazardous materials from entering the waste stream and -to the extent that this cannot be ensured.
Influencing Municipal Solid Waste Generation
With rising urbanization and change in lifestyle and food habits, the amount of municipal solid waste has been increasing rapidly and its composition is also changing. The increasing population directly influences the municipal solid waste generated in the surrounding areas. Again industrialization affects level of urbanization and increases population levels there by increasing the overall waste generated. The rate of waste generation covers community activities such as commercial, institutional, industrial and markets. It is also related to the economic level of different sectors in the community such as squatters, low, medium and high class residential area. Thus, the rate varies according to the type of waste generators and land use.
municipal solid waste generation
Composition of municipal solid waste provides a description of the constituents of the waste and it differs widely from place to place. The most striking difference is the difference in organic contents which is much higher in the low income areas than the high income, while the paper and plastic content is much higher in high income areas than low income areas. This reflects the difference in consumption pattern, cultural and educational differences. In higher income areas disposable material and packaged food are used in higher quantities; this results in the waste having higher calorific value, lower specific density and lower moisture content. In the case of lower income areas, the usage of fresh vegetables to packaged food is much higher. This results in a waste composition that has high moisture content, high specific weight and low calorific value.
Identification of waste composition is thus, crucial for the selection of the most appropriate technology for treatment, taking essential health precautions and space needed for the treatment facilities. Moreover, technology that seems to work for developed countries may not work for developing countries since waste composition varies from countries to countries, differences between geographical regions, between nations, between cities and even within a city. The list of differences between one location and another can be very long. Despite this recognition, there has been no study on the analysis of municipal waste composition in most developing countries. The ‘blind technology transfer’ of machinery from developed countries to developing countries and its subsequent failure has brought attention to the need for appropriate technology to suit the conditions in developing countries (type of waste, composition, etc.).
The composition may be broadly categories in:
- Biodegradable waste: food and kitchen waste, green waste (vegetables, flowers, leaves, fruits), paper (can also be recycled).
- Recyclable material: paper, glass, bottles, cans, metals, certain plastics, etc.
- Inert waste: construction and demolition waste, dirt, rocks, debris.
- Composite wastes: waste clothing, Tetra Packs, waste plastics such as toys.
- Domestic hazardous waste (also called "household hazardous waste") & toxic waste: medication, e-waste, paints, chemicals, light bulbs, fluorescent tubes, spray cans, fertilizer and pesticide containers, batteries, shoe polish.
Municipal Solid Waste
- Household waste: is produced from daily household consumption, and includes food waste, paper, plastic, metal and glass containers from the packaging of domestic consumables, and used fabric from clothing, cleaning rags, and bedding, among others. In developing countries, up to two-third of this category consist of kitchen wastes. In poor neighbourhoods, traditional cooking can also produce ash, and where sanitation facilities are limited, the waste might also include faecal matter. In wealthy countries discarded furniture, used appliances and garden wastes are included.
- Commercial waste: In developing countries, markets are an important source of commercial waste, much of it biodegradable. Other sources include shops, offices, restaurants, warehouses and hotels.
- Institutional waste: Solid wastes from schools, governmental offices, hospitals, and religious buildings are included in this category. Paper is the predominant waste from most institutional sources except those containing residences, such as barracks and nurses’ hostels, where the proportion of food waste is significant. Wastes from hospitals and other healthcare establishments should be segregated into two main categories – hazardous and general. Only the non-hazardous (general) wastes are the responsibility of the municipal authorities.
- Street sweepings: Street sweepings consist of sand, stones, spilled loads and debris from traffic accidents, as well as paper and plastic litter dropped by pedestrians and from vehicles or blown by the wind. They may also include appreciable amounts of household refuse and human and animal faecal matter.
- Drain wastes: In some cities the cleaning of open storm drains and culverts is linked to street sweeping. Silt from drains can be difficult to dislodge and is usually wet and very dense.
- Bulky waste: This includes items that are too big to be collected by the normal system for collecting municipal waste, and are not generated on a regular basis. Examples are old and unwanted furniture, mattresses and household appliances, and sometimes the carcasses of large animals.
- Foliage: Residues from gardening and pruning often have a very low bulk density, (unless they are shredded) and so can occupy large volumes in storage containers.
- Industrial waste: includes all materials generated from industrial production processes, and may include scrap metals, shredded wood, paper, plastics or other fabrics.
- Construction and demolition waste: derives from the erection of new buildings, or the refurbishment of old structures. This type of waste usually includes broken concrete, scrap wood and wood products, particle board, glass, old electrical materials, tiling and related masonry, old metal, and paints. Like industrial waste, construction and demolition waste is increasingly being recycled, especially in more developed countries.
- Mining waste: is often bulky, and results from the removal and/or relocation of overburden material such as soil or vegetation, in order to access minerals.
- Agricultural waste: is material generated from agricultural production and harvesting activities. This may include faecal matter from livestock production, green organic matter from fruit and vegetable production, and dried matter from the remnants of grain production and harvests. Waste from the agricultural sector may also be produced from the decomposition of bulk food harvests or contaminated material culled from food-crop infestations.
Some components of industrial, agricultural and mining waste are together broadly classified as hazardous waste. Household and other institutional waste, such as that collected from public offices, schools, hospitals and business places in urban and residential areas are classified as municipal solid waste.