2.2 Solid waste
Solid waste means all types of waste in solid form. It includes organic waste such as paper and leftover food, and inorganic waste such as plastic bags, cans and condoms. (Organic waste includes anything that is derived from living organisms; it decomposes by natural processes. Inorganic waste does not decompose so easily.)
Urban households and businesses generate a significant amount of solid waste. Plastic materials are long-term threats to the environment as they do not decompose easily. Coloured plastics are of particular concern because the sources of their colour are heavy metals such as lead, copper and chromium that are toxic to the environment. Use of plastics, particularly coloured ones, is actively discouraged in some countries, as is the case in India (Pradhan, 2000). However, their intensive use continues in developing countries such as Ethiopia, which adds to environmental pollution.
In schools, waste paper is a major component of the solid waste and where adolescent girls are students, menstrual pads can be an additional waste.
Restaurants, cafeterias and hotels generate a substantial volume of waste on a daily basis, including vegetables and other surplus food. These organic wastes quickly start to decompose, creating a strong and unpleasant odour and encouraging the growth of microbial pathogens (disease-causing agents). In addition, organic waste attracts mosquitoes, flies and rats, which can be responsible for spreading diseases. Such animals and insects are referred to as vectors of disease.
Health centres and clinics create different kinds of solid waste including used needles, gloves and bandages contaminated with body fluids from patients. These are all hazardous wastes that can cause harm to people. Waste in healthcare facilities is considered critical because new infections can occur in people dealing with the waste if it is not handled safely. Healthcare facilities are usually provided with incinerators that burn the waste at high temperatures to kill pathogens and remove any risk of new infections. Some facilities may have special storage containers for ‘sharps’ (i.e. items such as needles and razor blades), covered placenta pits for anatomical waste (blood, body parts), and open pits for other medical waste.
Market centres and public gathering areas produce significant volumes of organic and inorganic solid waste, such as plastic bags and packaging materials (Figure 2.1). Not only does accumulated solid waste create favourable conditions for pathogens and vectors to breed, it is also unsightly and a source of unpleasant odours.
To protect urban communities from these health threats it is critically important to establish a waste management system. A waste management system includes the complete chain of service from waste collection, through transportation, to final disposal in appropriate locations. This may include informal waste collectors and waste pickers, who make a living from waste (Figure 2.2).
In ideal conditions, solid wastes are safely collected and transported to a designated dumpsite. In practice, a significant proportion of waste fails to reach the dumpsite quickly. The resulting waste accumulation from households, institutions and industries can be significant. Often, this accumulated waste is meant to be temporarily stored before being transported to the final dumpsite. However you may have noticed the condition of containers, skips or barrels near where you live and seen the threats posed by such transient waste. Figure 2.3 shows an overflowing skip and illustrates the unsightly result of an inefficient system that doesn’t move waste in a timely manner.
Final disposal sites should have adequate facilities and be well managed to avoid threats to the people working in them. However, in most towns designated disposal sites with necessary equipment and/or infrastructure are not yet established. Efficient systems are needed along the complete chain of service – from collection to disposal – in order to protect urban communities from health threats.
Where population density is very high and adequate latrine facilities are unavailable, communities may use buckets or plastic bags for handling excreta. Sometimes such excreta is thrown to solid waste collection spots in the hope that they will be removed along with other waste material, a practice sometimes known as flying toilets. Human excreta contains harmful pathogens that can cause disease and is a health risk if not buried or treated. Flying toilets are particularly dangerous if thrown into rivers or recreational areas. In slums, or where adequate latrines have not been built, it is always prudent to assume that solid waste may contain human excreta.
Sometimes anal cleansing materials are collected into waste bins and eventually removed from the facility along with other solid wastes. Such wastes are obviously contaminated by human excreta and may pose additional health risks.
So far you have been learning about the direct impact of solid wastes. Solid wastes can also block drainage canals and flood channels, causing them to fill up and overflow, leading to problems like the situation illustrated in Figure 2.4.
List the major solid waste contaminants of the environment.
The major contaminants in this category are:
- organic waste from households, cafeterias and restaurants
- medical wastes
- plastics – especially coloured ones
- paper, cardboard and packaging waste.
If left in the open, as in the case of ‘flying toilets’, then faeces are also in the solid waste category.
What kinds of solid waste are commonly produced by:
- a.a household
- b.a school
- c.a health centre?
The answers are:
- a.A household might produce food waste such as vegetable peelings, leftover food, plastic bottles, bags, condoms and used menstrual pads.
- b.A school might produce food waste, waste paper and also used menstrual pads.
- c.A health centre might produce food and plastic waste as well as medical waste such as used bandages, syringes, needles, etc.
Instead of just discarding solid waste, a better approach to waste management is to adopt the 3 Rs approach. The 3 Rs stand for reduce, reuse and recycle. These three options can all contribute to improvements in the problems of waste disposal in urban areas. In order of preference, they are:
- Reduce the amount of waste produced. For example, throw away less food and avoid heavily packaged items.
- Reuse items many times before throwing them away. Bottles, plastic containers and bags can all be reused (Figure 2.5).
- Recycle wastes by using them to make new items. For example, paper waste can be recycled to make fire briquettes.