Solid Waste Management: Storage: Containers/Collection Vehicles

STORAGE:  CONTAINERS/COLLECTION VEHICLES

Containers/storage bins

The design of an efficient waste collection system requires careful consideration of the type, size and location of containers at the point of generation for storage of wastes until they are collected. While single-family households generally use small containers, residential units, commercial units, institutio and industries require large containers. Smaller containers are usually handled manually whereas the larger, heavier ones require mechanical handling. The containers may fall under either of the following two categories:

(i)      Stationary containers: These are used for contents to be transferred to collection vehicles at the site of storage.

(ii)   Hauled containers: These are used for contents to be directly transferred to a  processing plant,  transfer station  or disposal site  for  emptying  before being returned to the storage site.    

The  desirable characteristics of  a well-designed container  are low cost,  size, weight,  shape, resistance to corrosion, water tightness, strength and durability (Phelps, et  al.,  1995).  For example,  a container  for  manual handling by  one person should not weigh more than 20 kg, lest it may lead to occupational health hazards such as muscular strain, etc. Containers that weigh more than 20 kg, when full, require two or more crew members to manually load and unload the wastes, and which result in low collection efficiency.

Containers should not have rough or sharp edges, and preferably have a handle and a wheel  to facilitate mobility. They should be covered to prevent rainwater from entering (which increases the weight and rate of decomposition of organic materials) into the solid wastes. The container body must be strong  enough  to  resist  and  discourage  stray animals and scavengers from  ripping  it  as  well  as withstand  rough  handling by  the  collection crew  and  mechanical loading equipment. Containers should  be provided  with a lifting bar, compatible  with the hoisting  mechanism  of  the  vehicle.  The material used should be light, recyclable, easily moulded and the surface must be smooth and resistant to corrosion. On the  one hand,  steel  and  ferrous  containers  are heavy  and subject  to  corrosion; the rust  peels off  exposing  sharp  edges,  which  could  be  hazardous to  the collection  crew.

Communal containers

TYPICAL COMMUNAL CONTAINER

The use of communal containers is largely dependent on local culture, tradition and attitudes towards waste. Communal containers may be fixed on the ground (stationary) or movable (hauled). Movable containers are provided with hoists and tails compatible with lifting mechanism of collection vehicles and such containers have capacities of 1 - 4 m³. The waste management authority must monitor, maintain and upgrade the communal containers.  Note that in residential and commercial areas  in  India,  the  communal  containers  are  often made of concrete.  

 In  areas  with  very  high  waste  generation rates, i.e.,  rates exceeding  two truckloads daily, such  as  wet  markets,  large  commercial  centres  and large business establishments,   roll-on-roll  or hoisted communal containers with capacities of 12 - 20  m3   and a strong  superstructure with wheels are  used.         

 Normally,  the collection vehicle  keeps an empty container as a replacement before it hauls the filled container. When a truck is used as a collection vehicle, the use of communal containers may be appropriate.

This means that the farthest distance the householder will have to walk is 50 meters. However, in narrow streets with low traffic, where the house owner can readily cross the street, a longer distance is advisable. If the collection vehic le has to stop frequently, say, at every 50 m or so, fuel consumption increases, and this must be avoided.

Disadvantag es

The major disadvantage of communal containers is the potential lack of maintenance and upgrading. The residuals and scattered solid wastes emit foul odours, which discourage residents from using the containers properly.   In addition, if fixed containers  are built below the vehicle level, the collection  crew may be held responsible for sweeping and loading the solid  wastes  into  transfer  containers  before  being  loaded  into  the  collection  vehicle. Sweeping and cleaning the communal containers of residuals obviously impinge on the time of the crew members and take a longer time than if the wastes are placed in smaller containers. As fixed communal containers have higher rates of failure, their use is not advisable.

To overcome  the problem of   maintaining communal containers,individual residents should maintain  their  own containers  and locate  them in designated areas.  The communal area must have water and drains to facilitate the cleaning of the containers.  This practice has the advantage of reducing the number of collection   stops and   at   the same time   maintaining the   householder's responsibility for cleaning them. The residents must also be properly educated on the importance of good housekeeping  as the containers in the

          communal area are subject to vandalism. In the main, if communal containers are to be successful, the design of the containers, loading and unloading areas, and collection vehicle accessories should be co-ordinated.