Solid waste management can be thought of as a chain of linked stages, as shown in Figure 9.1. The chain begins with the generation of waste by individual households, institutions and workplaces. This is Stage 1, which you learned about in Study Session 7. Stage 2, covered in Study Session 8, is where the ‘3 Rs’ should be practised by separating the waste at source. This study session focuses on Stage 3. Waste treatment and disposal, the final stage, is covered in Study Session 10.
In this study session you will be guided through the principles and strategies for storing, collecting, transferring and transporting solid waste.
When you have studied this session, you should be able to:
9.1 Define and use correctly each of the terms printed in bold. (SAQ 9.1)
9.2 Explain the difference between primary and secondary waste collection arrangements. (SAQ 9.1)
9.3 Explain the need for solid waste transfer stations. (SAQ 9.2)
9.4 List possible solid waste collection equipment needed for small- and medium-sized towns. (SAQ 9.3)
9.5 Identify ways of involving private collectors to increase the efficiency of solid waste collection. (SAQ 9.4)
Solid waste is a major problem for cities in developing countries. It is considered to be a big challenge because it needs commitment, time and effort from businesses and householders to practise reduction, reuse and recycling. It also requires major financial investment as well as infrastructure development. A well-planned collection and transfer process can lead to significant reductions in the overall cost of waste management.
The national Solid Waste Management Proclamation sets out the regulations for waste management in Ethiopia. Its overall aim is to ‘… prevent the possible adverse impacts while creating economically and socially beneficial assets out of solid waste.’ (FDRE, 2007).
Among its clauses, the Proclamation makes urban administrations responsible for producing and implementing solid waste management plans. At the practical level, administrations are required to install waste bins in streets and public places, and to collect waste from these bins often enough to prevent them overflowing.
Ethiopia has a long way to go to achieve adequate waste collection systems in all its towns and cities. For example, in Addis Ababa, only 65% of the city’s solid waste was collected in 2003 (Regassa et al., 2011). More recent data indicates that this figure has since increased to 80% (Tessema, 2010; PPIAF, 2011). Even so, the city still has considerable progress to make. In other towns, the situation is worse. In Dessie, 48% of residents practise ‘open dumping’ of their waste (Sharma et al., 2012). In other words they deposit it on the roadside, on abandoned land, in open sewers or river banks, or around their yard. In Bahir Dar the collection rate was estimated in 2010 to be 67% and in Mekelle, until recently, only a third of total waste generated was collected by the municipality (Tefera and Negussie, 2015).
You read about some of the negative effects of poor solid waste management in Study Session 2. Make a list of the benefits to everyone of having a good waste collection system.
Your list will probably include the following. A good waste collection system can:
In Ethiopia and many other developing countries, collection is the most expensive stage of the waste management process chain – one estimate suggests that it demands 50–70% of the total budget (Tchobanogous and Kreith, 2002). So it is important that an effective collection system is in place.
The third stage of the waste management chain (Figure 9.1) begins when a householder or business employee puts their waste in a container. The choice of container will depend on several factors, including the wealth of the household and the amount of waste to be collected. It will also depend on the collection system – is it collected from outside the house or does the householder have to empty it into a communal container?
The simplest and cheapest storage containers for individual households are old lidded food containers, similar to Figure 9.2(a). You saw some other examples of simple domestic waste containers in Figure 7.4 in Study Session 7. It is easy for a householder to empty these containers into a communal bin for collection. At the other extreme are wheeled bins that can hold up to 240 litres of waste (Figure 9.2(c)). These need to be emptied into a vehicle fitted with lifting equipment. Any system using this type of bin needs well-maintained wide roads within 10 m or so of each property served.
Communal bins need to be larger than domestic containers and they should also be more robust. Often they need to be emptied by a specialised vehicle fitted with lifting equipment (described in the next section). Some examples are shown in Figure 9.3.
Effective waste management in needs commitment from both the local people and the kebele authorities. The people should use the communal waste containers in the correct way and avoid littering. In return, the kebele or town administration (or its contractors) should empty the containers at regular, predetermined times (for example, every Tuesday and Thursday morning) and keep the containers and immediate area clean.
After on-site storage, the next step is collection. Primary collection is the collection of waste from the point where it is placed by the person or organisation that has produced it. These collection points could be located outside each individual household and business, communal containers serving a number of households, or waste skips taking waste from households and businesses in the surrounding area. Depending on the collection vehicle and the distance to the waste treatment/disposal site, the waste at this stage may be taken to the final disposal site or to a transfer station, as described in Section 9.4.
Primary collection can be done in many ways. Table 9.1 summarises the lower-technology options that are suitable for collecting waste from households and transporting it to a transfer station or local disposal site. These all have the benefit of being able to serve narrow streets in crowded areas.
Secondary collections are where the waste from a number of primary collections is taken from the transfer station to the final disposal site. Table 9.2 shows some options for secondary waste collection vehicles, but note that some of these are also used for primary collections in certain situations.
|Only suitable for taking waste from households to a communal collection point. Good for narrow streets, but needs a well-maintained street surface.|
The additional wheels mean that this is more stable than the wheelbarrow (especially on poor road surfaces) and it is easier to move over longer distances. It can also carry a larger volume (1–2 m3).
Suitable for door-to-door collections in crowded areas and for transporting waste to communal containers at the ends of streets or to local transfer stations.
Can collect up to 3 m3 and transport the waste to a communal bin or transfer station. The cart has drop-down sides to make loading and unloading easier.
It needs a reasonable road surface and is not suitable for steep hills.
|Similar uses to the cycle cart. It has a drop-down end and, like the cycle cart, needs reasonable road surfaces and is not suitable for steep gradients.|
|A tractor has much higher costs than the above options, but can transport up to 4 m3 of waste for distances up to around 20 km to disposal sites or transfer stations.|
Truck fitted with bin lifter
A robust vehicle that can travel on rough roads. Suitable for transferring or collecting communal bins from residential and commercial areas.
Note that dump trucks without bin lifters are not recommended due to need for manual loading.
Enclosed light truck
|A waste collection tipper box fitted to a conventional vehicle chassis. Useful for emptying street-side litter and communal residential waste bins. Can serve narrower streets than most motorised collection vehicles but needs better roads than truck-based vehicles.|
Flatbed crane truck
Useful for collecting skips from transfer stations, markets and industrial areas.
Fitted with its own crane for loading and unloading.
The most expensive collection/transfer vehicle, costing around US$250,000. Hydraulic compaction equipment not suitable for residential waste (which already has a high density) and hydraulics need specialist maintenance.
Only suitable for collecting low-density waste in large quantities where road conditions are good.
Of little use outside major cities.
Most of the collection vehicles shown in Table 9.1 can only really transport the waste a short distance – a few kilometres at most. On the other hand, most of those shown in Table 9.2 are too large to collect waste from crowded urban areas and/or too expensive for most of Ethiopia. So unless the disposal site is less than around 3 km from the urban centre, the waste needs to be taken off the primary collection vehicle and loaded onto secondary collection vehicles. This is done at a transfer station. Waste can also be stored at a transfer station for a short time period where, in some cases, recyclable material is extracted from the mixed waste.
Transfer stations should be located conveniently close to all the communities they serve, but not too close to people’s homes or factories, schools, hospitals, etc. so that they cause a nuisance. They should also have access to major roads leading to the treatment or disposal sites.
Transfer stations have many advantages:
The simplest transfer stations consist of an area of hardstanding where skips are situated. The contents of primary collection carts are transferred to the containers manually (Figure 9.4).
In more complex transfer stations, the collection carts tip their waste onto a concrete floor and a mechanical loading shovel is used to transfer the waste to the skips (Figure 9.5). This allows the use of larger containers, so this type of station is more economical where distances to the waste disposal site are greater.
Looking at Figure 9.5, what are the measures being taken to protect the health and safety of workers and the general public?
The site is enclosed with walls, so only authorised people can gain entry to areas where machinery is being operated. Enclosure also keeps out scavenging animals and reduces wind-blown littering.
The site has a roof, so the rain is kept out and the waste cannot pollute surface run-off. The roof also reduces wind-blown litter.
Loading using a machine rather than people doing this work with shovels reduces human contact with the waste, which in turn lessens the risk of injury from sharp items (broken glass, metal edges) and the transmission of infections. (In areas with poor sanitation, the waste will contain human faeces.)
Transfer stations can be environmentally damaging, as shown in Figure 9.6. In contrast, a high-quality site with good fencing, hardstanding, lighting and an office/amenity building (Figure 9.7). will have little environmental impact. Of course, all waste transfer stations smell to some extent, but even this can be minimised by ensuring that waste is not stored for long periods.
Consideration also needs to be given to the transfer station staff, who will be exposed to all the waste hazards (including physical damage from sharp items, human faecal and other pathogens, heavy metals and dust and other chemicals). They should be provided with, and required to use, protective equipment (boots, gloves, hard hats, dust masks, high visibility jackets and safety glasses). An amenity room should also be provided for meal breaks and other breaks and handwashing facilities provided.
For any urban location, there is likely to be a number of transfer stations distributed around the town. The waste will need collecting from all these stations as well as directly from businesses, institutions and some households. In most locations, there is only one site for final treatment and disposal, to which the waste must be transported, and this is usually situated at the edge of the town. It is important to plan the routes for the waste collection vehicle (or vehicles) to make the best use of the resources available. This keeps costs down and gives people the best-possible service. Route planning is a complex operation, but the basic process consists of three stages:
One of the causes of a poor solid waste collection and treatment/disposal programme is a weak cost recovery system. This means there is no effective mechanism for collecting payments to cover the costs of the waste collection system. If the users of a service (the householders and businesses) do not pay for the waste collection and disposal service – either directly or through the kebele local authority – then there will be no funds available to pay wages, maintain the equipment or invest in new equipment and facilities. This leads to a decline in the service offered, which in turn leads to reduced income for the service providers, and so on. Private sector organisations can be better equipped than governmental organisations to collect payments and manage the finances. If they become involved in providing the waste management services, this spiral of declining services can be reversed.
Private companies may also have more experience of waste collection and access to better equipment than local government, resulting in better service provision. This arrangement, where the public and private sectors work together, is called a public–private partnership (PPP) or private sector participation (PSP). For example, a private sector company may be paid to collect a kebele’s waste and to collect payments from individual businesses and residents. If several companies are competing for the same PPP contract this should result in lower costs to the kebele.
Private sector operators became eligible to obtain permits to take part in waste collection, transport and treatment when the Solid Waste Management Proclamation was published in 2007 (FDRE, 2007). By April 2011, 524 firms in Addis Ababa had been permitted to collect solid wastes, employing 5800 people (PPIAF, 2011). Over the four years, the proportion of the city’s waste collected had risen from 60% to 80%, providing waste collection services to an additional 600,000 people.
Many of these private sector operators are ‘micro-enterprises’ (see Box 9.1). Under these PPP schemes, the planning and administration is the responsibility of the kebele authorities, who remain owners of the service (Tilaye and van Dijk, 2013). These micro-enterprises are responsible for operating the schemes. They collect waste from individual households, taking a fee from each household served and also receiving a fee from the kebele based on the amount of waste deposited at the central collection points/transfer stations. This helped to raise the proportion of waste collected, but the scheme was only semi-regulated, resulting in several collectors working in the same (well-off) areas and no collectors working in areas where residents could not afford to pay the collection fees.
You may come across several terms and abbreviations used to describe small businesses of different sizes. The various terms depend on the number of employees and the financial status of the firm. Precise definitions can vary, but one frequently used classification is:
Various abbreviations are used, of which SME, meaning small and medium-sized enterprises, and MSE are the most common. MSEs are micro- and small enterprises comprising businesses with fewer than 50 employees.
In 2008 the local government of Bahir Dar contracted a newly formed private company to collect, transport and dispose of the city’s waste. The company claimed that it could provide a better service at a lower cost. The scheme was assessed by Lohri et al. (2014). Waste is collected from outside houses and businesses by 270 collectors which carry or use hand-carts to take the waste to a network of around 100 collection points. At these collection points the collectors load the waste onto open trucks which are driven to an open dumpsite 7 km outside the city. The money to set up the scheme was provided by the government (56%), the United Nations (34%) and the company (10%), and the only income stream was from fees paid by the householders for the collections. The scheme was successful in that the proportion of waste collected rose from 50% to 67%. However, the fee income was only half the level expected, so the company had to use grants provided for capital equipment (vehicles, etc.) to pay staff wages. This meant that the scheme could not continue in the long term. According to Tefera and Negussie (2015), the municipality subsequently organised four additional MSEs to extend the system and improve waste collection rates across the city.
Solid waste management systems are developing in many Ethiopian towns and cities, but there is still considerable scope for improvement. Based on a study of Addis Ababa, Desta et al.(2014) identified several ways of increasing efficiency including:
To make significant and sustainable progress in solid waste management, an integrated approach that used a combination of these methods.
In Study Session 9, you have learned that:
Now that you have completed this study session, you can assess how well you have achieved its Learning Outcomes by answering these questions.
Explain whether the following waste collection vehicles would be better suited to primary or secondary collections:
Give four reasons why transfer stations are needed.
There are a number of reasons. The main ones are to:
Assume that you are a solid waste collection manager for a small town. What equipment would you need to run an effective solid waste management system?
This system would need:
How could you encourage private sector waste collection enterprises to serve households that cannot afford to pay for the service?
The private sector waste collection enterprises could be paid a fee directly from the kebele based on the total volume of waste that they deliver to the transfer station.