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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
5
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
6
Containers
7
4,000-5,000 L50-60 L
120-150 L
8
9
Vacuum pump discharge systemInput
Input
StorageDust chute
Input gateEmission gate
Truck with vacuum pump
Pipe line
10
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
11
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
12
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
13
Vehicle for Collection
14
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
15
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
20
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
21
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
26
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.
27
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.
28
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.
29
Residential collection routes
Residential collection routes
30
31
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)
32
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
33
34
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
35
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
36
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
37
Direct-Load transfer stations
38
Storage-load transfer stations (2)
Transfer Station
Drop-off Center
Recycling Center
Recycling Center
43
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
44
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
45
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
46