1. PB389 Integrated Solid Waste Management
Numfon Eaktasang, Ph.D.
Thammasat University

2. Solid Waste Management
generation
Waste reduction
and separation at the source
Collection
Transportation
Separation, processing & transformation
Disposal

3. Target of this chapter Material Recovery Facility (MRF) Reuse
Commingled wastes
Processing for recycle
Separated wastes
Source separation
Thermal treatment
Biological treatment
Landfill disposal

4. Waste minimization & the waste hierarchy
Prevent the creation of waste
or reduce the amount generated
Reduce the toxicity or negative impact
of the waste that is generated
Reuse in their current forms the materials recovered
from the waste stream
Recycle, compost, or recover materials for use as direct
or indirect inputs to new products
Recovery energy by incineration, anaerobic digestion or similar processes
Dispose of waste in an environmentally sound manner, generally in sanitary landfills

5. Waste minimization & the waste hierarchy
Past
Present

6. Terms in recycling Reuse Recycle Energy recovery
Products are recovered as they are and are reused for the same purpose without much treatment or change to the product.
For example: bottles, containers, plastic bags.
Recycle
The recovered waste material is treated and reprocessed to a new product whereby a new purpose could also result.
For example: plastics, organic waste
Energy recovery
The product is processed and the thereby resulting energy is used.
For example: incineration

7. Refuse-derived fuel: RDF

8. Waste Recycling 1. Inorganic fraction 2. Organic fraction Animal feed
Large dealers
Industry
Waste Recycling
Household
Recyclers
1. Inorganic fraction
2. Organic fraction
Collection
Composting
Transfer point
Collection
Agriculture
Disposal

9. What is recycled ? Anything that has value! Inorganics Metal Glass
Paper
Plastics
Aluminium
Organics
Food waste
Sometimes also batteries, oils etc.)

10. Who are the actors in recycling?
Household members
separating at source
Individuals
collection from house to house
on the road, at transfer stations (collection points)
on the disposal site
as employees in primary or secondary collection
Municipality/Government
if some recycling schemes are implemented
Small enterprises and dealers
as waste pickers or middle men, sometimes with treatment and/or processing steps
Large dealers
as middle men, often with storage, treatment, and/or processing steps
Industry
as buyer and final processing

11. The advantages of recycling
Advantages for solid waste management
Reduction of waste volume (example of Jakarta, Japan)
Cost savings for collection, transport and disposal
Longer life span for landfills
Less environmental impact of landfills
Advantages for the economy
Reducing imports for fertilizers or soil amendments (less foreign currency needed)
Job opportunities and income for the people
Cheap products (made from recycled materials) for the poor
Advantages for the environment
Sustainable use of natural resources (e.g. less energy consumption aluminium (-96%) and paper (-60%)

12. The main problems of informal recycling
Working conditions
Health risk due to contact with the waste (cuts, infections)
Inhaling of toxic gases (burning) and direct contact with infectious or toxic wastes
Contact with vermin or other vectors carrying diseases
Environmental aspects
Containers with paint residues or solvents are often burnt, polluting the air
Insulation plastics around wiring are burnt.
Cleaning of the products in open waters
Strongly fluctuating prices for the products
This makes it difficult to plan (business plan)
Imported cheap wastes undermine the local market

13. How can the situation be improved ?
It needs commitment of national and local governments
Recognise the importance of the informal sector.
Integrate them into the solid waste management system.
Give opportunities to recycle on household level or at transfer stations.
Promote and support the use of recycled products
Support programmes for social integration of ECO-HELPERS (refrain using terms like scavengers or waste pickers).
Support and try organising alternative organisation structure (partly formalised), e.g. co-operatives, if possible as close to the waste generation source as possible.

14. Planning a resource recovery center ?
Centralised
 "Economy of scale"
controlled work conditions
 high transport costs, as you need to transport your materials to the site and then transport the products back to the buyers.
Strong tendency to mechanize, making the center capital and maintenance intensive.
Decentralised Community-scale
 Products are nearer to the buyers
Less transport costs
As mostly small scale, then often adapted technology based on manual labour.
 Problems of space in densely populated areas.

15. Recycling organic material
As animal feed
As soil amendment or fertilizer
Composting (aerobic)
Vermicomposting
Co-Composting (solid waste together with faecal matter)
Digestion (anaerobic)
As fuel
Digestion (using the methane produced)
Pelletisation

16. Recycle and reuse opportunities
Important points in recycle and reuse
Available options for separation and processing
Economics of materials recovery
Materials specification

17. Use of materials recovered from MSW
Direct reuse
Furniture, bicycle, electrical appliance, bottle to bottle, …
Raw materials for remanufacturing and reprocessing
Aluminum, Paper and cardboard, Plastics, Glass, Ferrous metals, non ferrous metals, rubber, textile
Feedstock for production of biological and chemical conversion products
Compost (Aerobic), methane production (Anaerobic)

18. Use of materials recovered from MSW
Fuel Source
Combustion of wastes and recovering heat
Sometimes used for electricity generation
Converting some type of fuel that can be stored and used locally or transported distant energy market. (RDF = Refuse Derived Fuel)
Land Reclamation
Clean or processed demolition wastes

19. Typical materials specification
To consider quantity, shipment means, storage, and delivery point is important for all type of material recovery.
Direct reuse
Must be usable for original or related function.
Degree of cleanliness
Raw materials for remanufacturing and reprocessing
Aluminum: particle size, degree of cleanliness, and density
Paper and cardboard: grade, no magazines, no adhesives, and moisture content

20. Typical materials specification
Raw materials for remanufacturing and reprocessing
Plastics: type (PETE, PE, PVC, PP, PS, and so on…), degree of cleanliness, and moisture content
Glass: color, no labels or metal, degree of cleanliness, free from metallic contamination, no broken crockery
Ferrous metals: source, specific weight, degree of cleanliness, degree of contamination with tin, aluminum and lead
Non ferrous metals: vary with local needs and markets

21. Typical materials specification
Raw materials for remanufacturing and reprocessing
Rubber (cf. waste tires): recapping standard
Textile: type of materials, and degree of cleanliness
Feedstock for bioconversion product
Yard wastes: composition of material, particle size, particle size distribution, degree of contamination
Organic fraction of MSW: composition of material, degree of contamination

22. Typical materials specification
Fuel source
Yard wastes: composition of material, particle size, moisture content
Organic fraction of MSW: composition of material, calorific value, moisture content, storage limits
Plastics, waste oil, tires: depends on design of combustion equipment
Papers: up to local needs and markets
Wood: Composition, degree of contamination
Land reclamation
Construction and demolition wastes: composition, degree of contamination, local regulation, final land-use design

23. Important point for recycle materials
Storage, shipment means and delivery point
Transportation issue
Degree of cleanliness, degree of contamination
How we achieve good quality of materials for recycle.
Product design: material choice to separate easily and less contamination, easiness to disassemble
Design for Environment (DfE) in ISO14000s
Efficiency of separation process
Residents cooperation
Cooperation for separation
Choice of recyclable products

24. Source separation and collection
How to separate at source
Collected by different containers in a collection station
Discharge each separated waste for assigned day
How to collect separate wastes
By collectors: Each home, curbside or collection station in residential area
By homeowner (residents and businesses): Drop-off center, buy-back center

25. Drop-off and buy-back center
Homeowners bring the separated material to center
Low participation can be a problem
Require homeowners to store the materials until sufficient material is collected
How to encourage the participation
Make drop-off center at convenient place: shopping center, supermarket, station
Buy-back center provides a monetary incentive to participate
Residents are paid directly or indirectly through a reduction of collection fee.
Deposit refund system
Contest or lottery
Eco-station for shopping center in Japan
Lottery for discount ticket of shopping center

26. Cleaning packages and reuse
Deposit refund system
Manufacturer
Manufacturer
Cleaning packages and reuse
Product with package
Package
After
consumption
Retailer
Retailer
Product with package
Price + deposit
Refund
Package
Consumer
Consumer

27. Eco-station activity in Iiyama, Japan
Opening of eco-station
Collecting and lottery machine

28. Waste separation at MRFs
MRF (Material recovery facility)
Function as a centralized facility for the separation, cleaning, packaging, and shipping of large volumes of materials recovered from MSW.
Further processing of source-separated wastes
Separation and Recovery of reusable and recyclable materials from commingled MSW
Improvements in the quality (specifications) of the recovered waste materials.

29. Manual and mechanical separation
Manual separation
Flexible
Need more labors
Easy at source
Mechanical separation
Not flexible: need frequent maintenance
Less labors
Current trend
Integration of manual and mechanical separation

30. Unit operations in MRFs are designed
Unit operation in MRFs
Unit operations in MRFs are designed
To modify the physical characteristics of the waste
To remove specific components and contaminants from the waste stream
To process and prepare the separated materials for subsequent use
Category of operations in MRFs
Size reduction
Size separation
Density separation
Electric and magnetic field separation
Densification (compaction)

31. Size Reduction – type of equipment
Hammer-mill
effective with brittle materials
Shear shredders:
two opposing counter-rotating blades
Cut ductile materials
Tub grinder
Widely used for yard wastes processing

32. Hammer-mill shredder
Inner shaft is rotated at high speed, rev/min
Solid waste can not adhere to the hammer
Cutting action continues to until the material falls out of the bottom.
Either horizontal-shaft or vertical-shaft configuration
Horizontal-shaft is more reliable

34. Shear shredder Scissor-like action Low-speed devices
With two counterrotating knives or blades
Low-speed devices
rev/min
Need reversed action in the event of jam

35. Tub Grinder Essentially mobile hammer-mill shredder
Used for wide variety of materials
It consists of
tub with grinder for shredding
Engine for grinder
Loading equipment
Discharging equipment

36. Size reduction – selection of equipment
Factors to be considered
Materials to be shredded: Mechanical characteristics: shear strength and ductility
Size requirements: uniform or non-uniform
Method of feeding: capacity
Operational characteristics: energy requirements, maintenance requirement, simplicity of operation, reliability, noise, air and water pollution control requirements
Site considerations: floor space and height, access
Materials storage and conveyance requirements: for shredded materials
Safety issues: Explosion and fire
Potentially explosive: VOCs, spray cans
Explosive atmosphere: dust, high-speed impact of metal

37. Size separation Size separation = screening Reciprocating screen
Can be accomplished dry or wet.
Reciprocating screen
Vibrating screen
Trommel screen
Rotary drum screen
Disc screen

38. Solid Waste Management: Chapter 5
Vibrating screen
Application
Dry materials such as glass or metals
Wood chip for composting
Solid Waste Management: Chapter 5

39. Solid Waste Management: Chapter 5
Trommel screen
Versatile type of screen
Large-diameter screen
Rotating on a horizontal axis
Application
Protect shredder in RDF production (removing oversized materials)
Separate cardboard and paper
Solid Waste Management: Chapter 5

41. Disc screen An alternative to reciprocating screen Advantages
Self-cleaning
Capability of adjustment by varying the spacing of the discs on the drive shafts

43. Size separation – Selection of equipment
Factors to be considered
Waste characteristics: particle size, shape, bulk specific weight, moisture content, particle size distribution, clumping tendency, rheological properties
Materials specifications for screened components
Design parameters: size of opening, percentage of open space, total surface area, oscillation rate for reciprocating screens, rotational speed for trommel, elevation angle for trommel, loading rates and length
Separation efficiency: recovery, purity and efficiency
Operational characteristics: energy requirements, maintenance requirement, simplicity of operation, reliability, noise, air and water pollution control requirements
Site considerations: floor space and height, access

44. Thank You for Your Attention