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. Disposal Technologies
Landfill
Thermal treatment
Biological conversion

4. Dumping on Land

5. Burial

6. Hog Feeding

7. Thermal Treatment
Solid waste Ash + Gases + Vapor Smoke + Soot + Energy
(1°pollutant) (2°pollutant)
“conversion of solid waste into gaseous, liquid, and solid conversion products, with the concurrent or subsequent release of heat energy”

8. Thermal Treatment Open burning Air pollution Smoke Dust Health risk
Respiratory system
Eye irritation
GHGs

9. Thermal Treatment
Agricultural waste

10. Thermal Treatment Incineration Air pollution control system
Dust collection system
Ash

11. Categorization of thermal processing
Combustion
Stoichiometric: with exactly the amount of oxygen (or air) needed for complete combustion
excess-air: with oxygen in excess of the stoichiometoric requirements
Gasification
partial combustion of solid waste under substoichiometric conditions to generate a combustible gas containing carbon monoxide, hydrogen, and gaseous hydrocarbons.
Pyrolysis
thermal processing of waste in the complete absence of oxygen

12. What is incineration? Basic reaction of stoichiometric combustion
For carbon C+O2 CO2
For hydrogen 2H2+O22H2O
For sulfur S+O2 SO2
However, difficult to achieve complete combustion in stoichiometric condition practically.
Excess air must be used to promote mixing and turbulence
The use of excess air affects the temperature and composition of combustion products (called flue gases)
Excess air increase: oxygen contents increase and temperature of combustion decrease
Temperature of flue gas is important for odor control.
Less than 800 OC -> may occur odor problem
greater than 1,000 OC -> may minimize the emission of dioxins, furans, VOCs

13. Complete Combustion
3T’s of combustion
Time
Temperature
Turbulence

14. Complete Combustion C6H10O5 + 6O2 6CO2 + 5H2O + (Energy 5,000 Btu/Ib)
Theoretical combustion air (TA)
C6H10O5 1 Ib  oxygen requirement (6 × 32)/162 = 1.2 Ib
Theoretical air = 1.2 × (100/23) = 5.2 Ib
Excess air (EA) = excess air to complete combustion
Actual combustion air (AA) = total air to complete combustion
AA = TA + EA

15. Complete Combustion
Ex: Excess air 50% AA = 5.2 Ib + (0.5 x 5.2) AA = AA = 7.8 Ib
AA = TA + EA

16. Why is the SW incinerated?
To reduce the volume and weight of SW
1/4 by weight, 1/15 by volume
To remove the bad smell
To decompose the hazardous materials
heat of high temperature decompose the smelling and hazardous components

17. Where incinerated? Hikarigaoka Incineration plant Tokyo, Japan
maishima/01_kankyo.html

18. How incinerated?

19. Incineration plant platform Incinerator NOx remover Baghouse Ash pit
Gas cleaner
(HCl, SOx, HM)
Waste pit

20. Types of combustion systems
Waste type or combustion system
Commingled wastes: Mass-fired combustion systems
Processed wastes: Refuse derived fuel (RDF) fired combustion system

21. Types of combustion systems
Mass-Fired Combustion Systems

22. Types of combustion systems
Refuse derived fuel (RDF) fired combustion system

23. Types of Incinerators
Single chamber incinerator

24. Types of Incinerators
Multiple chamber incinerator

25. Types of Incinerators Incinerator type Stoker grate combustion
Fluidized bed combustion
Rotary Kiln
Small incinerator

26. Stoker grate combustion
Most common in mass-fired combustion system
Movement of waste through the grate system, mixing of the waste, and injection of combustion air. (RT=2hrs)
Air comes from below thorough the grate.
Ash falls down to the collection hopper to conveyer.
Temp ,200 0 C
Many variations of grates: travelling, rotating, reciprocating and rocking grates

27. Stoker grate combustion

28. Traveling Grates

29. Reciprocating Grates

30. Rocking Grates

31. Roller Grates

32. Stoker grate combustion
Advantages-Disadvantages
Temp ,200 o C
Commingled wastes
Various composition of wastes
Efficiency – 85%
1,200 ton/day
High investment and maintenance costs

33. Fluidized bed combustion (FBC)
Consists of a vertical steel cylinder with a sand bed, a supporting grid plate, and air injection nozzle.
When air is forced up, the bed fluidizes and expands up to twice its resting volume.
FBC are quite versatile and can be operated on a wide variety of fuels.
The bed material: plain sand, silica or limestone (CaCO3)
Limestone can contribute to decrease SO2 emission

34. Fluidized bed combustion (FBC)

35. Fluidized bed combustion (FBC)
Advantages-Disadvantages
Temp ,000 o C
Complete combustion
Processed wastes
Efficiency – 90%
ton/day
Low investment and maintenance costs

36. Rotary kiln
Rotary kiln is widely used for cement production and also used for industrial waste incineration, especially oily mud, tar, pitch, paint mud, dye waste, or plastics.

37. Rotary kiln

38. Rotary kiln Advantages-Disadvantages
Two-chamber incinerator (Temp. 700 and 1,200°C)
480 ton/day
Used for hazardous waste
Commingled wastes
Various composition of wastes
Efficiency – 80%
High investment and maintenance costs

39. Small incinerator
There are many kinds of anti-dioxins emission incinerators invented in Japan.
They are suitable for small scale waste treatment, not like uncontrolled combustion in open space.
Typical small incinerator
Dioxin-emission prevention type

40. Environmental Control Systems
Gaseous and particulate emissions
Solid residuals
Liquid effluents

41. Air emissions Nitrogen oxides (NOx) Sulfur oxides (SOx)
include NO and NO2
Source of NOx: Thermal NOx and fuel NOx
Precursors of the phtochemical oxidants, acid rain and fog
Sulfur oxides (SOx)
formed by the combustion of fuel containing sulfur
an eye, nose and throat irritant.
Asthma, bronchitis, acid rain
Carbon mono oxide (CO)
formed when insufficient oxygen is present
Headache, nausea, sudden death
Particle matter (PM)
Visibility reduction and effect to human lung
Metals
MSW usually has a higher metal concentration than coal or oil.

42. Air emissions Acid gases Dioxins (PCDDs) and Furans (PCDFs)
Not only NOx and SOx, but also Hydrogen chloride (HCl), Hydrogen fluoride (HF)
Iron corrosion, acid rain
Dioxins (PCDDs) and Furans (PCDFs)
75 PCDD isomers and 135 PCDF isomers
Some of them have been found to be among the most toxic substances in existence. (e.g. 2,3,7,8-TCDD)
Polychlorinated dibenzodioxin
Polychlorinated dibenzofuran
2,3,7,8-TCDD

43. Pollution control systems
Particulate
Electrostatic precipitators
fabric filters
NOx
Source separation
combustion controls
flue gas treatment
SOx and acid gas
wet or dry scrubbing
CO and HC control
Combustion controls

44. Electrostatic precipitator
first particle control device for MSW incinerators removing fine (<10mm) and very fine (<2mm) particles.
Mechanism
-20,000 to -100,000 V, applied to the discharge electrodes, produces a strong electric field between the electrodes.
The negatively charged particles in the flue gas attract to grounded collector electrode.
The collected particles are removed by mechanical vibration.
Typical performance
93% removal for fine, and 99.8% for very fine particles
does not meet the emission control requirement in some strict areas (countries) like Japan, California.

45. Electrostatic precipitator

46. Fabric filter
technology of choice on most recently constructed combustion systems.
Mechanism
Filter bags are connected in parallel in a housing.
Particles (>0.1mm) in the gas are trapped on a dust bed on the filter surface.
The particles are removed from the filter bags by mechanical shaking, reverse air flow, and pulse-jet.
Felted glass, woven glass, and Teflon have been used as fabric filters.

47. Fabric filter

49. NOx control Source (food and yard wastes) separation
for avoiding fuel NOx
Combustion control
for avoiding thermal NOx
Low excess air operation and staging of combustion
First stage; gasification with low-excess air, Second stage; combustion with excess air
Flue gas recirculation
Flue gas treatment
Catalytic reduction
Ammonia injection followed by a catalyst bed reaction (metals; copper, iron, chromium, nickel, molybdenum, cobalt, and vanadium).
NO + NH3 + 1/4O2  N2 + 3/2H2O (at 275 – 425 oC)
up to 90% removal for coal- and oil- burning applications

50. Acid gases control
Source separation of chlorine and sulfur containing wastes
Wet scrubbing of flue gases
liquid solutions are used to scrub and neutralize
Ca(OH)2 or NaOH solution added in venturi scrubber
Cooling before wetting and re-heating after wetting
Dry scrubbing
neutralizing slurries are injected
Na2CO3 or Ca(OH)2 added just before the baghouse

51. Dioxins, furans (DXNs) and metals control
Source separation is difficult for DXNs reduction, however, is working properly for metals reduction
Combustion control is the principal reducing strategy for DXNs
Minimum temperature in thermal system of oC with a minimum residence time of 1 sec
Minimization CO emission also minimize DXNs
Particulate control is also important for DXNs and metals
DXNs and most metals except mercury tend to condense on flyash particles <250oC and can be removed by filters
Temp of flue gas must not be kept around 300 oC (avoid De-novo)

52. Flow diagram of gas treatment
Dry scrubbing
(Acid gas)
Boiler
<850Co
<2 sec
Lime AC
Re-heater AC
Baghouse
PM removal
Na(OH)
Cooler
Re-heater
Cooling tower
Avoid De-novo
Baghouse protect
NH3
Wet scrubbing
(Acid gas)
Incinerator
Combustion control
NOx catalytic
reduction

53. Ash management Solid residuals Bottom ash Fly ash Scrubber product
Bottom ash, fly ash and scrubber product
Bottom ash
contains considerable amount of metals and glass as well as unburned organics.
Amount of unburned organic material in the ash is a measure of performance. (Ash Burnout Index, ABI)
sometimes used as a construction material
Fly ash
particulates removed from the flue gases
contains trace pollutants with fine particles, so careful handling is necessary.
Scrubber product
sludge produced by a wet scrubber

54. Ash management Heavy metals and trace organics, e.g. DXNs
Leaching potential in a landfill
EP toxicity test, Toxicity Characteristic Leaching Procedure (TCLP) test
Recommended ash-handling
Handling; Ash should be properly wetted or covered.
Transport; Ash should be covered and leak-resistant.
Disposal of flyash only; Disposal should be in a monofill (ash only) equipped with double liners and a leachate collection system.
Combined or bottom ash only; Disposal should be in a monofill equipped with a composite or clay liner, or by codisposal in an MSW landfill equipped with a double liner.

55. Wastewater Wastewater discharges
cooling and wash water from wet ash removal systems
wet scrubber effluents
wastewater from sealing, flushing and housekeeping
wastewater from boiler feedwater production
cooling tower blowdown
Quantities of wastewater produced are relatively minor, but may require pretreatment before discharge into a sewer system

56. Energy recovery systems
Recovered energy
electricity
steam (heat) using industrial processes or building heating
Principal components
boilers for steam production
steam or gas turbines and reciprocating engines as prime movers for mechanical energy
electric generator
Cogeneration systems
both thermal and electricity production

57. Energy recovery systems
Efficiency of electricity production
Average: 10% (overall efficiency, Japan, 2000)
many efforts to improve it
bigger facilities
improve electricity generation system
combined turbine
RDF
use more heat

58. Disposal method in Asia

59. Electricity production in major developed countries
Total capacity of electricity production by SW incineration (MW)
Number of SW incineration plants which produce electricity US UK
Germany
France
Sweden
Switzerland
The Netherlands
Japan
2,820
230
1,000
160
100
180
1,058
102 11 50 90 3 30 5
210
Source:

60. Thank You for Your Attention