soild waste management: collection and Transportaion of soild waste

 collection of soild waste:

Solid waste can be collected using a variety of methods, including curbside collection, door-to-door collection, and block collection. The method used depends on the type of waste, the size of the community, and the local infrastructure. 

Curbside collection 

·         Waste containers are placed at the curb on a scheduled day

·         Waste collectors empty the containers or collect the waste from the curb

·         This method is popular because it minimizes labor costs

 

Door-to-door collection 

·         Waste containers are placed outside the door when the waste collector arrives

·         This method is used in narrow streets where collection trucks can't reach individual houses

Block collection 

·         Waste containers are brought to a designated location at a set time and day

·         Waste is emptied directly into the collection vehicle

 

Community bins 

Waste is thrown into storage bins placed at convenient locations in the community

Other collection methods Alley collection and Set out set back service. 

When designing a solid waste collection system, it's important to consider the following: 

·         Collection frequency: How often waste should be collected

·         Route adjustments: How to adjust routes based on seasonal changes or population growth

·         Special waste needs: How to handle special events that generate large amounts of waste

·         Vehicle selection: What type of vehicle is best for the local conditions

Transportation of Solid waste:

The refuse collected at the roadside dust bins has to be collected and transported to the processing and disposal site by using a variety of vehicles. In general, these vehicles can be grouped into two types:

i) Vehicles which move through narrow streets and by lanes and do not travel a long distance before unloading their contents at a transfer station, processing or disposal facility.

ii) Vehicles which move through wider roads and travel long distances before discharging their contents at processing or disposal site.

In developed countries, both types of vehicles are used together. The vehicles collecting refuse from individual premises go to a transfer station where the load is discharged into another set of vehicles to be taken to the processing or disposal facility.

However, in India and other developing countries, transfer stations (except in a few cases as in Madras and Mumbai) are not used and the same vehicle which collects refuse from individual dust bins take it to the processing or disposal site. It is often seen that only one type (long haul type or short-haul type) of vehicles are used; whereas a combination of the two would have given better results.

The transportation of the wastes collected in the various community bins accounts for about 60-80% of the total expenditure incurred in solid waste management. The vehicles make a number of trips every day to the disposal site on routes.

 

II) Types of Transport vehicles used:

• Animal carts
• Short range diesel vehicles
• Tractor trailer
• Three wheeler autorickshaws
• Electric vehicles
• Dumper placer
• Container carrier system
• Special municipal vehicle
• Trucks
• Compaction vehicles
• Rail Transport

 

III) Planning of Vehicle Routes

If the routes of refuse vehicles are properly planned, the expenditure can be reduced and better service can be provided. In smaller towns where a single processing and/or disposal facility is in operation, planning of the routes is simple as it involves grouping of collection points into such routes which would require least transportation distance. In larger towns and cities, with more than one processing and disposal facility, the rational allocation is necessary. The points can then be grouped together to obtain routes with the least transportation distance.

Following approaches are helpful in planning vehicle routes:

• a) Heuristic
• b) Deterministic
• c) Deterministic-Heuristic

 

Heuristic Method

The old system of assigning routes based on experience and intuition is systemised by the formulation of some simple rules. However, their efficiency depends upon the experience of the user. The macro routing is to be done first followed by route balancing and micro routing.

The factors to be considered in micro routing are:

• i) Existing policies regarding the collection and its frequency must be identified.
• ii) Routes should not be fragmented or overlapping.
• iii) Collection and transport time should be reasonably constant for each route so as to equalise the workload.
• iv) The collection route should start as close to the garage as possible taking into consideration heavily travelled routes.
• v) Routes having heavy traffic should be served before or after rush hours only.
• vi) Sources where large waste quantities are generated should be serviced during the first part of the day.
• vii) Collection routes should be so arranged that the last bin emptied is nearest to the disposal site in that route.
• viii) In the case of one-way streets, it is best to start the route near the upper end of the street working down it through the looping process.

Deterministic Method

These methods use advanced mathematical techniques. In the existing system, much of the information regarding the location of collection bins, processing and disposal sites and quantities collected at individual collection bins would be available. In planning a new system, this data will have to be estimated for which simulation techniques have to be used.

Macro-scale attempts to study and plan the system was made to evaluate alternate solutions to the entire solid waste problem involving the generation, collection, treatment and economic planning of the whole system.

Models are prepared for

• i) uniform and continuous generation of waste along the streets,
• ii) house-to-house collection of refuse
• iii) use of transfer stations

Heuristic-Deterministic Method

In the heuristic-deterministic approach, a computer programme is used to examine many possible alternatives, out of which the best possible is chosen.

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