7 Waste collection – Storage containers and collection vehicles

Dr. Yogalakshmi K. N

Objectives:

To study in detail about

1.      Characteristics of storage containers used in waste collection

2.      Types of collection containers used in waste collection

3.      Location of collection containers

4.      Types of Collection vehicles used in waste collection

1.0 Introduction

Management of solid waste is crucial to avoid environmental and health hazards. Solid waste management is highly complex as it involves different steps, technologies and public participation. The steps involved in solid waste management include reduction in waste generation, handling, storage, collection, segregation, transfer, transport, processing, treatment and disposal. The success of waste management depends on the public and the government. Both share equal responsibilities and they should work hand in hand to achieve proper waste management.

Waste collection is the major and crucial step in waste management process. It is defined as the collection or gathering of waste from the source of generation and haul them to the transfer stations, processing sites, disposal site or landfills. Hence, waste collection does not mean the gathering of waste alone. Waste collection differs for comingled and source separated wastes. Source separated wastes (i.e) biodegradables, recyclables and non-recyclables are collected separately from different collection centres or containers and taken for further processing. Likewise, the comingled waste is carried to transfer station for further separation and processing. Waste collection is most difficult and complex in an urban environment because the generation of residential, commercial-industrial solid waste including recyclables takes place in every home, apartment building, commercial and industrial facility, and in the streets, parks, and even vacant areas. Henceforth, the waste collection becomes complex with increasing waste quantity and diffused waste generation pattern. More diffuse is the waste collection, more is waste generation and more complex is waste collection. Waste collection is costly component of waste management. Around 50 to 70 percent of the total waste management cost is utilized for waste collection. The cost can be reduced if the waste collection is properly planned and managed. Waste collection depends on number of containers, collection vehicles, routes and collection frequency. In the previous module, the various elements in waste management was outlined with a special emphasis on waste collection and its components. In this module we shall discuss about the waste storage containers, its types, characteristics and location of the containers. The various collection vehicle used for collecting the waste and transferring/transporting them to treatment and disposal site will also be discussed.

2.0 Waste collection containers

Waste collection containers play an important role in waste collection system. Their type, size and location determine the efficiency of waste collection. The size and type of the containers vary with the location and source of generation, example; residential colonies with the single family households require small containers unlike commercial, institutional and industries which require large containers. The size of the containers determines the handling of the containers (i.e.) small containers can be handled manually while the larger ones require mechanical handling.

2.1 Characteristics of Storage containers: The size and characteristics of storage container plays an essential role in waste collection. Selection of good container can save collection energy, increase the speed of collection and reduce the crew size. The characteristics to be considered while selecting a container include

• Low cost: The containers chosen for waste collection should be cheap and economical so as to minimize the cost of collection.
• Size and weight: Any collection containers should be of appropriate size to avoid occupational health hazard. A container should not weigh more than 20 kg. The containers that weigh more than 20 kg require more collection members as it would be difficult them manually. Further, if they are handled manually, it will cause muscular strain and ligament tear of waste collector. As mentioned earlier, single household families can use small sized containers unlike other residential, commercial and institutional sources. Smaller size containers can be unloaded manually where as large size containers require mechanical lifting.
• Containers should not be rough: Rough surface facilitates easy attachment of wastes there by leading to decomposition at the rough surfaces. Further containers with rough surface are difficult to clean. Example, containers made of wood.
• Containers should not have sharp edges: Sharp edges may cause injury to the waste collector crew.
• Containers should be inert: The containers should be made of inert materials to avoid the reactivity of waste with the container materials. Example, iron containers should be avoided because the moisture in the waste will corrode them and lead to rusting.
• Containers should be covered: Covered containers will prevent the entry of rain waste into the wastes. The rain water will accelerate the rate of decomposition leading to obnoxious odour. It will also increase the weight of solid waste stored within the container. Covered containers will prevent the entry of stray animals into the containers.
• Strength and durability: The containers should be strong and durable to avoid frequent breakage. It should withstand the rough handling by the crew members during manual and mechanical unloading of wastes. Strong and durable containers will last long and minimize the cost of collection.
• Containers should be provided with wheels to facilitate movement, handle for easy carrying and hoist and tail for lifting.
• The containers should not absorb moisture: Retention of moisture in bacterial and fungal growth, thereby accelerating the decomposition wooden containers, bamboo baskets should be avoided.
• the container will lead to rate of wastes. Example,
• The container material should be light, smooth, corrosion resistant, inert and recyclable.
• Containers that lack above mentioned characteristics should be avoided in waste collection as they would create menace, increase the collection cost and decrease collection efficiency.

2.2 Types of storage containers

Broadly, there are two principle types of collection containers: stationary and hauled/ movable containers.

Stationary containers: These are immovable and fixed at the site of storage. The waste stored in these containers is manually transferred by the waste collection crew. at certain times the stationary containers are emptied directly into the collection vehicle by mechanical means.

Hauled/ movable containers: These types of containers are fixed with wheels to facilitate its movement to waste processing site, transfer station or directly to the disposal site. These containers are used for special type of wastes (i.e.) when the wastes need separate treatment and processing.

Generally, there is third type of containers called communal or public containers. It is conventional type of containers that is in use for almost 3 to 4 decades. Communal containers are those which are fixed in public places such as parks, residential colonies, shopping streets, office buildings and institutions. They can be stationary (i.e.) fixed on the ground and movable. In India, these are cemented structure which is used by public to dump their wastes. These containers are open and hence face problems during rain. It also attracts flies, insects, rodents and other stray animals. Communal containers require manual cleaning which further increases the cost of collection. In containers built below the vehicle level requires swiping, cleaning and loading of solid wastes into the transfer containers before loading into the collection vehicle. This increases the collection time. In recent times these communal containers are provided with hoists and tails compatible with collection vehicles lifting mechanisms. Such movable communal containers are generally of capacity, 1 to 4 m3. However in places of high rate waste generation (large commercial centers, wet markets and other business establishments) the capacity of communal containers ranges from 12 to 20 m3. The major disadvantage of these communal containers is, they emit foul odour due to limited maintenance. High rate of failure is .observed in fixed communal containers.

Source: http://www.wastecontainer.co/en/products/waste-container/four-wheeled
Figure 1 Hauled containers

Figure 2 Stationary containers

2.3 Location of containers

A container should be placed in an appropriate location to ease waste collection. The container should be placed at a distance of 100 to 200 meters. Larger distance between the container and the source of generation will discourage people from dumping the wastes into the container. The location of the container will depend on

• The width and length of the lane/ road.
• Ease of collection vehicle to reach the containers
• The amount of waste generation and type of source generation example, commercial, residential, institutional etc.
• Traffic congestion

In narrow roads, the collection containers can be placed equidistantly at a distance of 100 meters. The containers can be placed alternatively on either side of lane. Example, on one side the distance between two collection containers can be 200 meters while on the other side of the lane, the distance can be 100 meters. In case of narrow streets with low traffic congestion, the containers can be placed at a longer distance. A resident will fail to walk 50 meters to dispose the waste into the containers. Another disadvantage of placing the container at short distance would be increased fuel consumption of collection vehicle. Stoppage at every 50 meters will increase the fuel consumption of the collection vehicle. It is always better to place the collection container at the end of the street, this would minimize the collection and the transportation cost.

Figure 4 Location of containers

3.0 Waste collection vehicles

The collection vehicles are of different types, classified based on their size, and compaction. Three types of collection vehicles viz. small scale collection and muscle powered vehicles, non compactor trucks and compactor trucks. The selection of collection vehicle depends upon the nature and density of wastes, terrain or location of the area, density of population, strength and capability of collection crew. The different types of collection vehicle used in municipal solid waste collection is described below

3.1 Small scale collection and muscle powered vehicles

These vehicles are commonly used in rural and hilly terrain. Vehicles such as rickshaw, bullock carts and tricycles manually are usually used for this purpose. These vehicles are comparatively low cost and easy to construct and maintain. These vehicles are appropriate for areas with dense population having narrow streets with comparatively less quantity of waste generation. Restricted travel range of these vehicles and exposure of weather which influence humans and animals are some of the disadvantage associated with these waste collection vehicles.

3.2 Non compactor trucks

Non compactor trucks are known to be relatively more efficient and affordable. These vehicles are generally utilized in small cities. These are used for dense waste that has minimum potential for compaction. These compactor trucks have capacity of in the range of 10-12 m3 and are generally used to cover small distances of less than 15 km. The non compactor trucks are usually covered to avoid flying of waste material and entry of rain water into the waste. These trucks are preferred when labour cost is high. Similar to muscle power vehicles non compactor trucks are also operated by single person.

Source: http://www.brainkart.com/article/Solid-Waste-Management–Vehicle-storage-method_4034/

Figure 7 Non compactor trucks

3.3 Compactor trucks

These vehicles are provided with compaction system to hydraulically compact the waste. Compaction increases the capacity of these trucks by 2-2.5 times. The capacity of these vehicles range between 12 to 15m3. The compactor trucks are suitable for narrow roads. However, small collection vehicles such as tricycles and bullock carts can discharge their waste into these compactor trucks. The vehicles are provided with lifting mechanism to discharge the waste from stationary containers located at the source of generation. The empting of the containers can be done from the rear, front or sides of the vehicles. The compactor trucks can carry waste directly from the source of generation to waste processing site.

The major advantages of compactor trucks include large size, higher capacity, covered and safe for waste handlers due to minimum exposure. The compactors trucks cannot be used for waste that are dense, wet, gritty, dusty and abrasive waste.

3.4 Specialized collection vehicle

The specialized collection vehicles such as closed body recycling trucks, recycling trailers, modified flat bed trucks, flat bed trucks, open bin recycling trucks and compartmentalize trucks are mainly used for collection of wastes segregated at the source. In developed countries large wastes storage containers are located outdoors or basement for collection of recyclables. The recyclables are further transported to the processing site through specialized collection vehicles.

3.4.1 Standard packer trucks: It is a specialized collection vehicle used for the collection of recyclables. Vehicles with rear loading have been used for newspaper, cardboard and magazine collection. Special trailers attached to the rear loading packers are used for can and gas collection. While collection glass and cans, compacting mechanism is not used as glasses are highly abrasive and would damage the packer plate also unbroken glass would facilitate easy sorting at the processing site. Similar to rare loading packers, front- end loaders are used to collect newspapers, glass and can from apartment buildings.

3.4.2 Closed body recycling trucks: The trucks consists of an enclosed steel body installed on a lowered truck chassis, low entry walk in cab fitted with left and right driving control. The body of these trucks is provided with adjustable hinged dividers to create 2 to 4 compartments. The overall capacity of these trucks range from 24.6 to 28 meter cube. The trucks can be loaded manually by opening one or both sides of the compartment and mechanically with front mounted telescopic hoist.

3.4.3 Mobile container system: It consists of a steel frame with a set of hydraulic fork used to transport large winds. Around 3 to 6 winds can be transported by this system. The waste is loaded into the system by lowering the fork-lifts to the ground, through which the bins are lifted over and slided into channels on the under side of the bins. The empty bins are hydraulically raised and secured to the trailer frame and replaced in its original position.

3.4.4 Modified flatbed trucks: The standard flatbed truck is used for the curbside collection. In these types of vehicles, there is hydraulic dumping box fitted on the top of the truck bed. The dumping box has 3 or 4 compartments which have the standard volume of around 14.7 m3.

3.4.5 Open bin recycling truck: This type of specialized collection vehicle have 2 or 3 self dumping bin with exposed top. The waste is emptied mechanically into the bins through low mounted truffs. The capacity of front bins is around 5.4 m3 to 7.3 m3 and back bins are 9.1 m3 to 11 m3. The wastes from the back bins are discharged from the rear side of the vehicle.

4.0 Types of collection system

The waste collection systems are classified based on the mode of operation, equipment used and type of waste collected. Based on the mode of operation, the collection system is characterized into two types, hauled container system and stationary container system.

4.1 Hauled containers

In this type of collection system, the waste containers are hauled to discharge the waste directly to the transfer station, material recovery facility or disposal site. This system is commonly used in places where the size of the containers is large and rate of waste generation is relatively high. Large containers will avoid waste accumulation, unsanitary condition and improper use of small containers. The major advantage of hauled container system is their flexibility to use containers of different size and shape. They are also available for the collection of any type of waste. Hauled container system also minimizes the size of collection crew as it requires one truck and a driver for a round trip to the waste processing or disposal site. Highly compressible waste can also be transported to the hauled container system. This system always requires one collector driver for collection and emptying the containers. In rare cases a helper is attached. There are three main types of hauled container system, mainly hoist truck, tilt frame container and trash trailer.

Hoist truck systems: Hoist truck system previously were used at military setting up but after the arrival of self loading waste collection vehicles, its usage has been restricted to few pick up points where huge waste is generated where newer and efficient system would incur high cost.

Tilt frame container system: Tilt frame loaded vehicles are used for collection of rubbish and other solid waste. Tilt frame loaded vehicles along with the large containers are called as drop boxes or roll of containers. Large volume of waste can be hauled with the tilt frame loaded vehicles due to which they are popular among private collection services.

Trash trailer system: It is similar to that of tilt frame container system. They are best suited for carrying heavy rubbish such as metal, timber and sand. They are often used in construction sites, to collect demolishing waste.

4.2 Stationary container system:

Stationary container system is used to collect all type of waste. In the stationary collection system, the storage containers remain at the source of generation. According to the type and quality of waste to be handled, the stationary container system are classified into two types

1. Systems in which the collection vehicles are loaded manually: This system is commonly used for collecting residential source separated waste, litter and co-mingled waste. Manual loading is done at places where the waste generation is small and the accessibility to pick up points is difficult for mechanically loaded vehicles.

2. Systems in which the collection vehicles are loaded mechanically: The capacity of these containers used in mechanical containers is 0.9 m3. It facilitates ease of loading and provides greater flexibility. In some cases large containers are also used as a substitute for number of small containers. This system is not suitable for the collection of heavy waste. Example, industrial waste and rubbish.

The stationary container system involves worker fatigue and increased capital and maintenance cost. The personnel requirement for the stationary collection system varies from one to three depending upon the type of service and collection equipment.

5.0 Summary

• To summarize, in this module we have familiarized about
• Storage containers and its characteristics
• types of storage containers and their location criteria Collection vehicle and their types
• types of collection systems

References

• George Tchobanoglous, Frank Kreith (2002) Handbook of Solid Waste Management, Second Edition, Mc Graw-Hill publication.
• TV Ramachandran (2009), ‘Management of Municipal Solid Waste’. Centre for Ecological Sciences, IISc Karnataka research foundation.
• www.nptel/Municipal solid waste management.com