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EN361Solid Waste and Excreta Management

Numfon Eaktasang, Ph.D.

Thammasat University

Solid Waste Management

Waste generation

Waste reduction and separation at the

source

Collection

Transportation Separation, processing &

transformation

Disposal

3

Definition of “Collection”

Not only the gathering or picking up of solid wastes from the various sources

But also hauling of these wastes to the location where the contents of collection vehicles are emptied.

Unloading of the collection vehicle is also a part of collection operation.

Waste generation

Waste handling, separation, storage, and processing at the source

Collection

Transfer and

transport

Separation, processing and transformation

Disposal

4

Major issues in collection system

High personnel cost

Lack of equipmentLack of infrastructure (Road)

Residents’ awareness

Lack of institutional setup

Traffic congestion

Aesthetic problem

Hygiene problem

Developed

Developing

Labors safety

High fuel cost

Lack of fund

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Method for discharge

Using a bag Paper or plastic

Uncomfortable for wet wastes Resource consumption and potential of pollution

Using a plastic tank, container or bin Easiness of loading to the vehicle

Development of mechanical system

Dust chute and vacuum pump Aged society

Containers

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Containers

7

4,000-5,000 L50-60 L

120-150 L

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9

Vacuum pump discharge systemInput

Input

StorageDust chute

Input gateEmission gate

Truck with vacuum pump

Pipe line

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Place for collection

Each house In front of house, curbside

Stationary Mobile: who moves container to roadside and return?

Station Curbside, Apartment

Tank or storage Vacuum discharge Mobile container system

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Who collects?

Stakeholders in waste collection general collection

Local government Private company which is committed by municipality NGO cooperation

Recycle House (apartment) owner, supermarket cooperate to set

up collection station Company which has responsibility for waste materials

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How do they collect?

Vehicle Size, energy

truck (motor), rickshaw (manpower)

Hauled container or stationary container Hauled Container system

Large container is used: for large sources Reduce handling time and labor Special truck for hauling container

Stationary Container system Flexible for all types of waste Mechanically loading or manually loading Compactor?

boat, barge Vacuum pump collection

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Vehicle for Collection

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Analysis of collection systems

Necessity to know the vehicle and labor requirements Need unit time required for each task, picking up,

hauling, unloading,…. Required time for some task is not so different in

each city: picking up, unloading We can use the universal data.

Required time for other task might be different in each city: hauling or transporting Distance, traffic condition, vehicle speed, are different.

Type of Collection

CurbAlleySet out-Set backSet outBackyard Carry

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1. Curb

Point 1 Point 4Point 3Point 2

2. Alley

Point 3Point 1

Point 2 Point 4

Type of Collection

3. Set out-Set back

Type of Collection

4. Set out

Type of Collection

5. Backyard Carry

Type of Collection

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Important elements for analysis

Pick up: Required time and laborHaul:

Between collection points Between collection point to unloading station

At-site (Unloading): Required time and laborOff-Route

Necessary: checking, traffic congestion, equipment maintenance

Other: lunch, break, mobile phone….

Collection System

1. Stationary container system (SCS)Automatic systemManual system2. Hauled container system (HCS)Conventional modeExchange container mode

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Stationary container system (SCS)

1 2 3 n

Empty collection

vehicle from dispatch station-

beginning of daily route(s),

t1

Solid wastes pickup location

Drive loaded collection vehicle to

location where contents of vehicle

will be emptied

Load contents from container(s) at pickup location

into collection vehicle

Drive to next pickup location

Transfer station, MRF, or disposal

site

Drive empty collection vehicle to beginning of next collection route or return to dispatch

station-end of route

Hauled container system (HCS)

1. Conventional mode

1 2 3 n

Haul empty container to

original pickup location

Haul loaded container

Truck from dispatch station

beginning of daily route, t1

Container location

Pickup loaded container

Deposit empty container

Drive to next container

Truck to dispatch

station–end of daily route, t2

Transfer station, MRF, or disposal site (contents of

container are emptied)

2. Exchange container mode

1 2 3 n

Haul empty container to originally at location 1 to location 2

Haul loaded container from

location 1

Truck from dispatch station beginning of daily route, t1

Container location

Truck with empty

container to dispatch

station–end of daily route, t2

Transfer station, MRF, or disposal

site

Deposit empty container from

previous location and

pick up loaded container

Hauled container system (HCS)

Exchange container mode

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Collection Routes

Decision of collection routes Important to use both collectors and equipment

effectively No universal rule (series of trial) Field experience of collector-driver is also important

Route supervisor in large municipality

Schedules Should be prepared after deciding the collection

routes.

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Deciding Collection Routes

Key issues1. Existing policy and regulations. (frequency, point of collection)2. Existing system characteristics. (labor, vehicle)3. Routes begin and end near arterial streets.4. Routes should start at the top of the grade and proceed downhill.5. Last container should be located nearest to the disposal site.6. Sources at traffic-congested locations should be collected as

early.7. Sources at extremely large quantities of waste should be

collected during the first part of the day.8. Scattered sources with same collection frequency should be

served during one trip or on the same day.

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General steps for deciding routes

1. Preparation of location maps showing pertinent information on the sources

2. Data analysis and preparation of information summary table

3. Preliminary layout of routes4. Evaluation of the preliminary routes and

development of balanced routes by successive trials.

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Residential collection routes

Residential collection routes

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Alternative techniques for analysis

Analysis is largely based on experience and intuition

New tools has been developed, but have not been widely used. Systems approach, operations research, etc… Enormous cost with the collection and processing of

field data

Advanced approach Data base of collection information with GIS

(Geographical Information System)

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Transfer and Transport

Sources of solid waste

Collection

Treatment (processing, transformation)

Disposal

Reuse, Recycle

Transfer station or Transfer facilities (TF)

Materials Recovery Facility (MRF)

Collection

Transport

Transport

Transport

Transfer Station

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Need for transfer and transport operation

Small vehicle to Large transport equipment Saving cost and energy consumption

Factors which make the use of transfer operation attractive Processing or disposal site is remotely located. Decrease the occurrence of illegal dumping due to excessive

haul distance Encourage the use of small-capacity collection vehicles For Low-density residential area Encourage the use of small containers in a hauled container

system Encourage the use of other collection and transport medium

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Category of transfer stations

Conventional transfer station Remote location of final destination Change medium of transportation

Materials Recovery Facilities (MRFs) Usually include the function of transfer operation

Materials Recovery / Transfer Facilities (MR/TFs)

Transfer station at landfill Safety concerns Restrictions of landfill operation

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Type of transfer stations

Direct-load Wastes are emptied

directly into the equipment used for transportation

Storage-load Wastes are emptied into a

storage pit

Combined

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Direct-Load transfer stations

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Storage-load transfer stations (2)

Transfer Station

Drop-off Center

Recycling Center

Recycling Center

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Transfer station design requirements

1. Type of transfer station Direct or storage, MRF or no MRF

2. Capacity requirements Economic trade-off between

Collection vehicles have to wait for unloading Large capacity of transfer station

3. Equipment and accessory requirements4. Environmental requirements

Air treatment, wind screen, fire proof construction

5. Health and safety of workers

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Location of transfer stations

Requirements As near as possible to the weighted center of the

individual solid waste production areas Within easy access of major arterial road Minimum of public and environmental objection Construction and operation are most economical

Site selection based on Cost, Operational constraints

Waste allocation problem for several transfer station Transportation problem in the field of Operations

Research

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Transport means and methods

Motor vehicle transport Trailer, semi-trailer, compactor Requirements

At minimum cost, Wastes are covered, Highway traffic, Within allowable weight limit, Unloading operation is simple

Railroad transport Train

Water transport Barges, scows, and special boat

Hydraulic system Ex. Disposer in kitchen for food waste

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