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Newsletter and Technical Publications
<Municipal Solid Waste Management>

Sound Practices
Collection and transfer

1.3.2 Sound technical options - collection

Collection vehicles

Almost all forms of collection are based on a collector or collection crew which moves through the collection service area with a vehicle for collecting the waste or materials. This vehicle may be small and simple assmall as a two-wheeled cart pulled by an individual or large, complex, and energy intensive, such as the rear-loading compactor trucks used in many industrialized cities.

The collection vehicle selected must be appropriate to the terrain, the type and density of generation points, the roads and ways it must travel, the type of waste or the kinds of materials it will be used to collect; the strength, stature, and capability of the crew that will work with it; and the point and manner of discharge of its load. If the vehicle is to be used for multiple purposes, it must be suited to all of these.

 

Muscle-powered or micro-mechanical vehicles work well:
  • in densely populated areas with little street access or unpaved streets;
  • in squatter settlements;
  • on hilly, wet, or rough terrain; and
  • where there is relatively small volume of waste from a relatively large number of densely settled housing units.
The disadvantages of muscle-powered vehicles include:
  • the perception by some that the use of animals or human power is old-fashioned or shameful;
  • the fact that the vehicles have limited traveling range and are generally slower than fuel-powered vehicles;
  • the fact that animals pulling such vehicles leave waste, which must be cleaned up;
  • the fact that weather exposure has a greater effect on humans and animals when they are not in motorized vehicles; and
  • the problems of animal temperament, health, etc.

Small-scale collection and muscle-powered vehicles
Muscle-powered carts or wagons and relatively small rickshaws pulled, pushed, or pedaled by people, bicycles, or animals are an important sound practice for MSW collection in many developing countries, as well as in rural hilly areas of transition countries. Such vehicles are inexpensive and easy to build and maintain, compared with other vehicles. In many cases muscle-powered vehicles represent the soundest mix of capital, labor, and available resources for waste or materials collection.

Small-scale collection can also be accomplished with use of electric or propane-powered vehicles servicing a small or inaccessible area in conjunction with a larger "host" vehicle. Muscle-powered primary collection (or micro-collection) may be coupled with transfer into a larger "host" vehicle at the edge of the neighborhood; this is sometimes done with street sweeping or materials recovery in industrialized countries.

Non-compactor trucks
Non-compactor trucks are more efficient and cost-effective than compactor trucks in small cities and in areas where wastes tend to be very dense and have little potential for compaction. The use of lighter, more energy- efficient box-trucks, vans, and dump trucks can be appropriate for sparsely populated areas, where the main constraint on collection efficiency is distance.

 

Advantages of non-compactor trucks
Non-compactor trucks are a sound technical practice for solid waste collection under the following conditions:
  • the waste is generally very wet or dense;
  • labor is relatively inexpensive, compared to capital;
  • there is limited access to highly skilled maintenance;
  • collection routes are long and relatively sparsely populated;
  • controlling capital and operating costs is very important; and
  • downtime for maintenance must be minimized.
Disadvantages of non-compactor trucks
The main problem with the use of non-compactor trucks is not technical, but political:
  • government officials tend to see compactors as a means to modernize their waste collection system; they view non-compactor trucks as having low status;
  • equipment salesmen recommend compactor trucks as the only method for proper waste transport. This may be true in most industrialized countries but is not true in most developing countries; and
  • donor agencies from industrialized countries tend to recommend equipment that is associated with efficient collection in their own countries, and tend to assume that compactor trucks represent an appropriate use of their aid monies.

 

"Love Bandung, Love Cleanliness"
"Love Bandung, Love Cleanliness." Public education can be built into collection vehicles. This collection vehicle uses locally made parts.
(credit: Antonio Fernandez)

When non-compactor trucks are used for waste collection they usually need to have a dumping system to easily discharge the wastes. Nevertheless, dump trucks, which have a high loading height, may not represent the best choice for a non-compactor truck. Non-compactor trucks generally need to be covered in order to prevent residues flying off the truck and/or rain soaking the wastes.

Compactor trucks
In industrialized countries and cities, the use of compacting vehicles of some type has become the standard of sound practice for waste collection. A compactor truck:

  • allows waste containers to be emptied into the vehicle from the rear, the front, or the side;
  • compacts the waste to a high density using hydraulic or mechanical pressure;
  • removes the waste from view quickly; and
  • inhibits vectors and insects from reaching the waste during collection and transport.

Compactor trucks have the following characteristics:

  • high capital cost;
  • sensitive hydraulic mechanisms which must be well maintained in order to function; these can break when an attempt is made to compact waste that is already dense.
  • high fuel usage and operating cost;
  • moderate skill level to operate;
  • at least two persons needed to operate under most conditions.

The best practice in terms of compacted collection in industrialized countries is European semi-automated collection with 120-liter or 240-liter rolling carts, a practice which is rapidly becoming the norm in Western Europe.
Operationally, these trucks:

  • require a driver and one or two crew members;
  • are usually equipped with two separately cycling lifts that dump into discrete containers, and therefore have the capability to subject two separate waste streams to differing compaction pressures; and
  • can have two separate compartments which can be dumped separately or in different locations.

 

Compactor trucks work well where:
  • there are paved streets wide enough to allow passage and turning;
  • the waste is set out in containers or bags, so that crews can pick them up quickly; and
  • the density and moisture content of the waste are low.
Compactors work poorly where:
  • the waste stream is either very dense or very wet, such as mixed waste in developing countries, or newspapers in developed countries;
  • the materials collected are source separated organics or materials with septic content; compaction tends to squeeze out the moisture and discharge it as leachate;
  • collected materials are gritty or abrasive; or
  • the roads are very dusty.

The central characteristics of a collection system based on dual collection compactors is:

  • the containers are uniform, large, covered, and relatively visually inoffensive;
  • health risks to the collectors and odor on the streets are minimized;
  • the waste is relatively inaccessible to waste picking; and
  • monitoring compliance with source separation protocols is difficult.

Selection of set-out containers

Most collection systems depend on some kind of set-out container. In industrialized countries, this is usually a paper or plastic bag, or a metal or plastic garbage can. Scandinavian countries tend to use 120-liter kraft paper bags in a metal or wooden frame. In developing countries or rural areas, set-out containers include bags, pots, plastic or paper bags, cane or reed baskets, concrete or brick vats, urns, boxes, clay jars, or any kind of container available.

In some places, waste is stored in a pit in front of houses while awaiting collection. In other places, any container at all can be used to store or organize waste. In many places, storage containers are insufficient and waste is simply piled or heaped on the street or on the ground to await collection.

In places with community transfer, residents use bags or baskets for carrying waste to the containers. Plastic bags, which are increasingly available, are becoming a problem for composting.

For certain recyclable materials, industrialized countries have developed special containers. These include blue boxes for recyclables in Canada and the US, and 120-liter rolling carts in much of Europe.

Container materials, size, and volume. The choice of set-out container has an important effect on collection effectiveness. Containers like baskets or paper bags allow wastes to have contact with air, which promotes decomposition while discouraging formation of anaerobic odors.

In developing countries (as well as in transition and to some extent industrialized countries) theft of containers is a major problem. Sometimes even large plastic bags are stolen. This must be factored into all decisions about set-out.

Larger containers encourage generators to keep wastes for longer before setting them out. In locations with cold winters, for example, the use of a larger container allows generators to comfortably accumulate several weeks' waste before setting it out. This efficiently dovetails with less frequent collection.

Container color. Brightly colored containers that contrast with the surrounding environment increase the speed and ease with which the crew can dump the waste into the vehicle. If collection occurs at dawn or dusk, or in the dark, the visibility of the set-out container is also a factor in determining how quickly collection can proceed, and in preventing missed containers. On the other hand, collection containers should not be too attractive or they may be stolen for other domestic uses.

Container design and materials recovery from waste set-outs. The waste collection container has a large effect on the feasibility of recovering materials from the waste prior to collection. In systems where the goals are to facilitate waste picking prior to collection (to reduce, among other things, the volume of waste to be collected), the container should be low to the ground, wide mouthed, not too large for an individual to manipulate, and stable. Where the goal is to discourage waste picking, use of a taller container can be beneficial.

Special recycling containers. Providing a separate container for recyclable materials has been associated with formal recycling systems in the US and Canada, and with composting in Europe. This approach can also facilitate orderly and efficient waste picking by giving the residents an opportunity to separate materials designated for the waste pickers.

Wheeled carts for automated collection. In places where automated collection systems are in use, the container must be compatible with the lift and dumping system on the collection vehicle, and usually must have wheels.

Route design and operation

Collection service areas and routes
Collection of waste or recyclables tends to be organized into service areas. A service area is the region or area which falls under the responsibility of a government, public authority, or private company. Within the service area, collection is organized into routes. A route is the path followed by a single collection vehicle for waste collection on a single day.

Collection efficiency
Collection efficiency is critical to sound practice as it is the main determinant of collection cost in all types of collection systems. While cost control is increasingly important all over the world, in some cases authorities place a higher priority on employing people or arranging collection at a particular time of day, thus raising collection costs. The savings realized from moving toward efficient collection methods can be used for other social needs.

An efficient collection system aims to collect as much waste as possible with a given amount of labor, capital, and time. If collection takes place at a time when streets are crowded with bicycles or market booths, the ability of the vehicle to travel its appointed route will be diminished. If the vehicle has too small a volume to handle the waste that is generated on the route, and must make several trips to dump the accumulated waste or materials, the amount of time available for collection decreases. If the points of generation, such as households, are too far apart, as they are in rural areas of North America or Scandinavia, the vehicle can spend too much of its time traveling.

Sound practice in collection route design
The design of an optimal collection system, therefore, involves far more than the choice of vehicle alone. There is a complex interaction of factors, and ignoring any one of them can result in a collection system which is inefficient or does not successfully meet the policy or technical objectives of the collection program.

Curbside, alley, or backyard collection. A common point of collection in both developing and industrialized countries is at the curbside or the alley; the resident places full waste containers at the curb or in the alley behind the residence and retrieves them empty. This represents sound practice in many situations. Backyard collection is much less common, but is used in wealthier areas of some industrialized countries where there is a strong wish to keep waste out of the public eye, backed up by a willingness to pay for the added cost of such service.

Collection frequency. Sound practice depends on well-chosen collection frequency and timing. In developing or tropical cities, collection occurs as often as once per day, but there is disagreement regarding optimal collection frequency. In most industrialized cities, collection occurs once or twice per week, and even more frequently in urban areas where storage space is limited. Areas with a high density of small retail shops, hotels, and restaurants usually require daily collection.

Sound practice in setting collection frequency should include analysis of the appropriate volume for containers, the needs and desires of the area or neighborhood, the public health risks that would arise from infrequent collection, avoidance of odors from uncollected waste, and the necessity of scheduling collection at times when streets are not crowded.

"Just-in-time" collection. Some cities use "just-in-time" collection systems, where residents bring out their wastes at the time the collection vehicle reaches a certain spot and signals its presence. This system reduces the health hazards associated with wastes on streets and roadsides, and prevents unauthorized waste picking.

Just-in-time collection only works when households typically have someone at home to carry out the waste at the proper time. To enhance reliability, the collectors can ring a bell or announce their presence from a loudspeaker upon arrival in an area. In squatter settlements in Bombay, an adaptation of the bell system is that the crew have hand carts to fit into narrow lanes and walk along ringing a bell; then they take the carts back to the vehicle on the road.

A Dutch adaptation is to have a truck collecting hazardous wastes move through the neighborhood during the day, and then take up a stationary position at a centrally located point (such as a shopping center) in the neighborhood for several hours at the end of the working day, to allow those who were not at home to deposit their materials.

Special collections. Special materials, such as bulky items, white and brown goods (old appliances and electronics), furniture, leaves, construction materials and tree stumps, must often be collected separately, due to their size and the fact that they are generated irregularly. Sound practice in this area includes:

  • making the rules of collection clear to all residences and businesses;
  • collecting with adequate frequency to prevent build-up on the streets; and
  • coordinating collection with the industries and individuals who would like to have these materials for repair, salvage, dismantling, or materials recovery.

Crew size and makeup. The size, capability, and motivation of the crew is a basic factor in determining efficiency of collection Some variations on sound practice are described below.

Single driver-collector. All vehicles, whether muscle-driven or mechanical, require a driver, and one crew model is that the driver does the collection as well. This is the case in small-scale neighborhood collection in developing countries, but also in Canadian blue-box recycling collection or in rural collection routes in the US, Canada, and Scandinavia. Single driver-collector models represent sound practice where:

  • the size and volume of the set-outs is small;
  • not every stop has set-out materials; and
  • the distance to be traveled is relatively long in relation to the quantity of materials to be collected.

Driver separate from collection crew. A second model of sound practice is that the driver remains in the cab, on the bicycle seat, or at the head of the animal and does no collection. A crew of one or more people walks or rides between set-outs and does all the work of picking up the material. This model represents sound practice:

  • in relatively dense areas;
  • where the distance from one stop to the next is too short for the driver to get out, load the material, and get back in, but easy for the crew to walk;
  • where the volume of waste is high in relation to the distance to be traveled;
    or
  • where the drivers are in a separate union category that does not permit them to handle waste, although it can be useful to renegotiate such rules.

Interchangeable driver and crew. A third model, the most common and a generally sound practice, involves a revolving crew, where more than one member can drive, and the drivers also assist with the loading.

Individual operators who collect fees. In cases where the collectors pay for material, there is more interaction with the generators during collection, and handling the money is a significant part of the work of collection. These cases frequently involve a single individual with his or her own vehicle or carrying pack, and usually depend on nearby middlemen to buy the collected materials.

Equipment repair and maintenance
Sound practice requires preventive maintenance of equipment, including vehicles, containers, transfer points, and tools. Maintenance includes periodic preventive equipment repair, worn parts replacement, lubrication, and replenishing fluids. For waste-related equipment, daily or periodic cleaning or washing is also highly recommended.

Poor maintenance of collection equipment is a well-documented problem in most developing countries. It is not uncommon for one-third or more of the municipal fleet to be out of service at any one time. However, industrialized countries also suffer from this problem. A 1996 report documented that nearly 40% of the collection vehicles in Washington, DC were not functioning properly. This situation has in some instances been an impetus toward privatization of collection services or at least of vehicle maintenance. For developing countries, the use of imported or high-technology collection vehicles that cannot be procured or repaired locally makes this problem still worse, and can stimulate the "cannibalizing" of parts from vehicles which could be repaired.

Improvement in maintenance, together with the selection of collection systems that are available locally, is a key element of sound practice in collection systems.

Promising innovations
The increased emphasis on recycling in many industrialized countries has produced a generation of dual, or divided, compacting vehicles in Europe, and a large number of divided recycling trucks in the US and Canada. Dual collection vehicles are used for co-collection of waste and recyclables, or for organics and recyclables, or for organics and waste. This represents a promising direction for all areas suited for compactors in the first place. Divided vehicles of all types have the advantage of allowing separate collection in a single collection pass, thus saving energy and labor on collection.

 

Communal Collection Point in New Delhi
At this communal collection point in New Delhi, recyclables are usually sorted out and not sent for disposal.
(credit: Chris Furedy)

Communal collection

Communal collection, which is very common in developing countries, involves individuals bringing their waste directly to the collection point, usually a container that can be accessed by foot. In a somewhat similar vein, some European cities require residents to take their wheeled containers to the corner on the day of collection and retrieve them when empty. Industrialized countries also use communal collection in rural areas, where most of the waste is brought by car, or for separate collection of recyclables, household hazardous waste, or special materials such as leaves in the autumn.

Communal collection is a particularly appropriate means of organizing collection where household collection is impossible or marginally feasible, where inadequate resources are devoted to poor areas, or where local customs promote it. The solid waste authority may choose to provide containers on each street corner, at several places on a densely populated street, or at a point on the edge of a neighborhood that is accessible both to generators and collection vehicles.

An advantage of communal collection points for drop-off of household waste is that these facilities provide more or less continuous access to disposal or materials recovery facilities. Disadvantages of communal collection arise from the fact that such facilities may receive little attention from municipal authorities. Additionally, residents may deposit dangerous materials in or near the container.

Sound practice in communal collection design requires recognition of the inherent conflict between the physical demands imposed by public convenience in disposal and the strategies required to maintain cleanliness and control waste pickers, odors, vectors, animals, and flies and other insects.

Sound practice also involves ensuring that there are an adequate number of containers that are easy to use, even for children. The responsible authority must carry out very frequent collection (often daily) and must be committed to cleaning up overflows.

Ideally, communal containers should be designed to prevent animals from getting access to the contents. While tall containers or those with small openings or heavy lids may accomplish this purpose, they are also difficult to use, especially for children.

Summary of principles for designing collection systems

The principles outlined below represent sound practice, with special reference to the needs of developing countries.

Principles for selection of collection vehicles
Selection of a collection vehicle as the basis for a collection system involves the following guidelines:

  • Select vehicles which use the minimum amount of energy and technical complexity necessary to collect the targeted materials efficiently. High energy prices and vehicles that are difficult to repair both raise the cost of collection. The trade-offs here depend significantly on the relative cost of capital and labor.
  • Choose locally made equipment, traditional vehicle design, and local expertise whenever possible, supplemented if necessary by assistance from national or international experts. This is the core of sound practice for developing countries, where there is a long history of internationally provided vehicles that are not appropriate for the waste stream, do not work well in the climate, and break down after only a few months of service.
  • Select equipment that can be locally serviced and repaired, and for which parts are available locally. This is especially true for developing and transition countries, where half of the collection vehicles are often out of service due to lack of parts (sometimes due to foreign exchange constraints) or limited repair capabilities. Selection of local equipment is less important in industrialized countries, as long as replacement parts are readily available.
  • Choose muscle- and animal-powered or light mechanical vehicles in crowded or hilly areas or informal settlements in developing countries.
  • Choose non-compactor trucks, wagons, dump trucks, or vans where population is dispersed, or waste is already dense. These trucks are lighter, more fuel-efficient, and easier to maintain. In addition, these trucks generally offer lower capital and operating costs in return for higher labor requirements. In developing and transition countries, in particular, this may be an advantage.
  • Consider the advantages of hybrid systems where appropriate: satellite muscle-, electric-,or propane-powered small vehicles feeding a larger slow-moving or stationary compactor truck or container. Many cities combine an old city center with a modern commercial center, wealthy outskirts, and poor neighborhoods. The appropriate collection vehicles for each of these areas differ greatly.
  • Consider compactor trucks in industrialized urban areas where roads are paved, collection routes serve many generators, and waste is not dense or too wet.
  • Choose European-style automated collection vehicles in industrialized countries when automated collection is desired, and when sidewalks and streets are suitable for containers to be wheeled from the household to the curb or the corner. These allow for the use of the relatively large 120- to 240-liter rolling carts, which in turn make it possible to collect less frequently.
  • Select dual collection vehicles in industrialized areas where separate collection of organics or other recyclables is a priority. The use of dual vehicles allows for the efficient collection of two material streams.
  • Select specialized recycling collection vehicles for collection of commingled recyclables in industrialized countries or in highly industrialized cities in developing countries. The last ten years have seen rapid development of these specialized vehicles, which may provide compaction for plastics, dry storage of paper, and a provision for collection of separate colors or grades of glass, metal, and plastic.

Principles for selection of set-out containers
A similarly conceived set of principles constitutes sound practice when choosing or designing a new system of set-out containers:

  • Choose containers made of local, recycled, or readily available materials. Sometimes designing an attractive and uniform container can significantly alter public waste practices and effect a change in behavior. The use of recycling blue boxes in North America successfully stimulated an enhanced perception of recycling and increased the capture rate from 20% to 75% in some areas.
  • Choose containers which are easy to identify, either due to shape, color, or special markings. There is some advantage to specifying a set of uniform containers when introducing a new collection system, as this communicates the official nature of the collection and adds to perception of importance.
  • Choose containers which are sturdy and/or easy to repair or replace. This is essential to sustainability of a collection system over the long term.
  • Consider identification of containers with generators by address or name or code number. Sometimes having a name or address on a container introduces a greater sense of responsibility and a tendency to keep the container clean and/or retrieve it promptly after emptying from the point of set-out.
  • Choose containers that are matched to the collection objectives: easy to open and empty to facilitate waste picking; large enough for storage of materials between collection days; small enough for manual loading if necessary; etc.
  • Choose containers that are appropriate to the terrain: on wheels where there are regular paved streets; waterproof where it rains a lot; heavy where there are strong winds, etc.

 

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