Solid and Hazardous Waste Management
Chapter 1: Introduction
1 By Dr. Sompop Sanongraj
Engineering Approach:
“In order to solve a problem, you must first be able to break it down into its basic elements, characterize it, describe it mathematically, formulate the physics, chemistry and biology, quantify it, and ultimately measure the results” (John H. Skinner, Executive Director and CEO the Solid Waste Association of North America quoted in Solid Waste Engineering, Vesilind et. al., 2002)
Preface:
Introduction
Figure 1-1 Ocean-dumping Barge: The New York Bight at the turn of the 20th century (Vesilind et. al., 2002)
2 By Dr. Sompop Sanongraj
Figure 1-2 Mobro Barge: The hapless voyage that cruised up and down the East coast in 1987 searching for a community that would let it dock and off-load its waste (Vesilind et. al., 2002).
Integrated Solid Waste Management
“All creatures, humans included, constantly make decisions about what to use and what to throw way”
“A chimpanzee knows that inside of the banana is good, and that the peel is not, and throws it away. And humans buy a can of soft drink with the full understanding that the can will become waste.”
“Waste is a consequence of everyday life”
3 By Dr. Sompop Sanongraj
Solid Waste in History
Figure1-3 Evolution of vehicles used for the collection of solid waste: (a) horse-drawn cart, circa 1900; (b) solid tire motor truck, circa 1925; and (c) modern collection vehicle equipped with container-unloading mechanism (Tchobanoglouset. al.1993)
Economics and Solid Waste“One (of many) possible potentially beneficial alternatives toward global stability is to eliminate solid wastes generated by our materialistic society that are now deposited on increasingly scarce land. The recovery of these resources from solid waste would be a positive step toward establishing a balanced world system where society is no longer dependent on extraction of scarce natural ores and fuels. It seems quite clear that society has to adapt, using less technology in some instances, more in others, to achieve this balance ”
4 By Dr. Sompop Sanongraj
Materials Flow
Figure 1-4 Materials Flow through Society (Vesilind et. al., 2002)
4Rs for achieving reduced material use and waste generation
1. Reduction
2. Reuse
3. Recycling
4. Recovery
5 By Dr. Sompop Sanongraj
Recycling vs. Recovery
Recycling is the collection and processing of the separated waste, ending up as new consumer product.
Recovery is the separation of mixed waste, also with the end result of producing new raw materials for industry.
Figure 1-5 Plastic Recycling Symbols (Vesilind et. al., 2002)(Vesilind et. al., 2002)
6 By Dr. Sompop Sanongraj
Recovery Defined as the process in which the refuse is collected without prior separation, and the desired materials are separated at a centralfacility; a materials recovery facility (MRF)
Figure 1-6 Typical Materials Recovery Facility (Vesilind et. al., 2002)
Recovery New topic: MRF produce refuse-derived fuel (RDF)
Pyrolysis produce fuel
Figure 1-7 Refuse-Derived Fuel (RDF) (Vesilind et. al., 2002)
7 By Dr. Sompop Sanongraj
Integrated Solid Waste Management (ISWM)
EPA has developed a national strtegy for the management of solid waste, called the integrated solid waste management:
- Reducing the quantity of waste generated
- Reusing the materials
- Recycling and recovering materials
- Combusting for energy recovery
- Landfilling
8 By Dr. Sompop Sanongraj
Chapter2: Municipal Solid Waste (MSW) Characteristics and
Quantities
2-
Solid and Hazardous Waste Management
9 By Dr. Sompop Sanongraj
Defined as having the following components:
- Mixed household waste
- Recyclables such as newspapers, aluminum cans, milk cartons, plastic soft drink bottles and other material collected by the community
- Household hazardous waste
- Commercial waste
- Yard (or green) waste originating with individual household
- Litter and waste from community trash cans
- Leaves and other green waste collected from community street and parks
-Bulky items (refrigerators, rugs, old cars etc.)
- Construction and demolition waste (C &D)
- Water and wastewater treatment plant sludges
refuse
2-
In summary:
MSW = (refuse) + (C &D) + (sludge) + (leaves) + (bulky items)
On the basis of MSW:(as generated MSW) = (as collected MSW) + (diverted MSW)
On the basis of refuse:(as generated refuse) = (as collected refuse) + (diverted refuse)
10 By Dr. Sompop Sanongraj
Example 2-1A community produces the following on an annual basis:
Fraction Tons per year
Mixed household waste 210
Recyclables 23
Commercial waste 45
C & D 120
Treatment plant sludge 32
Leaves and miscellaneous 4
Calculate the diversion base on MSW and refuse?
Solution:
Based on MSW,
The diversion is = [(23+120+32)/434]x100 = 40%
Based on refuse,The diversion is = [(23)/(210+23+45)]x100 = 8%
11 By Dr. Sompop Sanongraj
MSW Generation
Table 2-1 Generation of All Types of SW in the United States, 1998 (Franklin Associates, 1999)
Figure 2-1 Historical trends in MSW generation and composition in the United States (Franklin Associates, 1999).
12 By Dr. Sompop Sanongraj
Figure 2-2 Historical trends in MSW as per capita generation (Franklin Associates, 1999).
Refuse Generation- Varies throughout the year
- Varies throughout the season
- Varies throughout the week
- Varies throughout the day
etc.Remarks
- Collection frequency affects the production of refuse.
-Income and affluence tend to have a effect on refuse generation.
- Population density has an uncertain effect on refuse generation.
- Cost of disposal and retail sales seem significantly to affect the rate of solid waste production.
13 By Dr. Sompop Sanongraj
MSW Characteristics
- Composition by identifiable items (steel cans, office paper, etc.)
- Moisture content
- Particle size
- Chemical composition (C,H, etc.)
- Heat value
- Density
- Mechanical properties
- Biodegradability
Composition by identifiable itemsOn a nation level: used the data from published industry production statistics for estimating waste composition, called the input method of estimating solid waste production.
Table 2-2 : Generation of Municipal Solid Waste Components in the United State, 1998 (Vesilind et. al., 2002)
14 By Dr. Sompop Sanongraj
On a local level: used an output method of analysis and perform sampling studies.
Sampling Studies:
- Sample Size- Method of characterizing the refuse:
- Manual- Other techniques such as photogrammetry
Measuring Composition by Manual Sampling
“First, the waste has to be accurately represented through proper load selection”
The most frequently used methodology for determining the number of samples required in order to achieve statistical validity is “the American Society for Testing and Materials (ASTM): Standard Test for Determination of the Composition of Unprocessed Municipal Solid Waste (ASTM designation D 5231-92)
15 By Dr. Sompop Sanongraj
ASTM designation D 5231-92- Number of samples required to achieve the desired level of measurement precision.- A suggested sample mean and standard deviation for waste components (typically, 90% confidence)
As a crude first estimate, sorting and analyzing each 200-lb sample to get statistically confident in the results.
Figure 2-3: Approximate number of 200-lb samples required to achieve desired precision (Vesilind et. al., 2002)
16 By Dr. Sompop Sanongraj
To obtain representative 200-lb (90 kg) samples, ASTM recommends quartering and coning.
Quarteringafter well mixing
Coning
A 200-lb sample
Figure 2-4 การเก็บตัวอยางขยะ เทศบาลเมืองวารินชําราบ จังหวัดอุบลราชธานี (Envi-Expert, 2540)
17 By Dr. Sompop Sanongraj
List of components for samplingFor example,Paper: newsprint, corrugated cardboard, magazines, other paperMetal: aluminum cans, steel cans, other aluminum, other ferrous, other nonferrousGlass: clear, green, brownPlastic: HDPE, PETE, other plasticsYard wastes: wood (branches and lumber, leaves and clippingsFood wasteOther: rubber, ceramics, rocks, etc.
Table 2-3: Bulk Densities of Some Refuse Components (Vesilind et. al., 2002)
18 By Dr. Sompop Sanongraj
Moisture Content:
M = [(w-d)/w]x100%
where M = moisture content, wet basis, %w = initial (wet) weight of sampled = final (dry) weight of sample (in an
oven at 77oC (170oF) for 24 hr)Some engineers define moisture content on a dry weight basis,
Md = [(w-d)/d]x100%where Md = moisture content, dry basis, %
Table 2-4: Moisture Content of UncompactedRefuse Components (Vesilind et. al., 2002)
19 By Dr. Sompop Sanongraj
Solution:M = [(w-d)/w]x100% = [(100-76)/100]x100 = 24%
Particle Size
The average particle size, defined as that diameter where 50% of the particle (by weight) are smaller than --- and 50% are larger than --- this diameter.
(Vesilind et. al., 2002)Figure 2-5: Particle-size distribution curves for two mixtures of particles (Vesilind et. al., 2002)
20 By Dr. Sompop Sanongraj
For nonspherical particles, the diameter of a particle may be defined as any of the following:
3
3
2where particle diameter length width height
D lh w lD
D hwl
D hww lD
Dlwh
=+ +
=
=
=+
=
====
Example 2-3Consider nonspherical particles that are uniformly sized as length, l = 2, width, w = 0.5 and height, h = 0.5. Calculate the particle diameter by the various definitions mentioned previously.
3
2; 1.25; 1.02 3
1; 2.12Note that the "dismeter" varies from 1.0 to 2.12, dependingon the definition.When particle size is determined by sieving, the most reasonable
definition
w l h w lD l D D
D lw D hwl
+ + += = = = = =
= = = =
is D lw=
Solution:
21 By Dr. Sompop Sanongraj
When the mixture of particles is nonuniform, the particle size is often expressed in terms of the mean particle diameter.
1 2 3
1 2 3
1 1 2 2 3 3
1 2 3
the arithmetric mean:....
3the geometric mean:
....the weighted mean:
........
nA
nG n
n nw
n
D D D DD
D D D D D
WD W D W D W DDW W W W
+ + +=
= × × ×
+ + +=
+ + +
1 1 2 2
1 2
33 31 1 2 2
2 2 2 2 2 2 2 2 21 1 2 2 1 1 2 2 1 1 2 2
41 1 2
3 3 31 1 2 2
the number mean:...
...the surface area mean:
...... ... ...
the volume mean:
...
n nN
n
n nS
n n n n n n
Vn n
M D M D M DDM M M
M DM D M DDM D M D M D M D M D M D M D M D M D
M D M DDM D M D M D
+ +=
+ +
= + ++ + + + + +
= ++ +
442
3 3 3 3 3 31 1 2 2 1 1 2 2
...... ...
where number of discrete classifications (sieves) = weight in each classification = number of particles in each classificati
n n
n n n n
M DM D M D M D M D M D M D
nWM
++ + + +
=
on
22 By Dr. Sompop Sanongraj
Chemical Composition
-The proximate analysis: an attempt to define the fraction of volatile organics and fixed carbon in the sample.
- The ultimate analysis: an attempt to define the fraction of elemental compositions in the sample.
Table 2-5: Proximate and Ultimate Chemical Analyses of Refuse (Vesilind et. al., 2002)
23 By Dr. Sompop Sanongraj
Heat Value: calorimeterTable 2-6: Heat Value of Fuels (Vesilind et. al., 2002)
Usually, the heat value of the refuse is expressed in terms of all three components including organic materials, inorganic materials and water.
Sometimes the heat value is expressed as moisture-free (the water component is subtract from the denominator).
Or sometimes the heat value is expressed as moisture- and ash-free (the ash, being defined as the inorganics upon combustion, also need to be subtract from the denominator).
24 By Dr. Sompop Sanongraj
Example 2-4A sample of refuse is analyzed and found to contain 10% water (measured as weight loss on evaporation). The Btu of the entire mixture is measured in a calorimeter and is found to be 4000 Btu/lb. A 1.0-g sample is placed in the calorimeter, and 0.2 g ash remains in the sample cup after combustion. What is the comparable moisture-free, and the moisture- and ash-free heat value?
the moisture-free heat value:1g4000 Btu/lb 4444 Btu/lb
1g - 0.1g waterthe moisture- and ash-free heat value:
1g4000 Btu/lb 5714 Btu/lb1g - 0.1g water- 0.2g ash
× =
× =
Solution:
Table 2-7: Heat Values of Some Refuse Components (Vesilind et. al., 2002)
25 By Dr. Sompop Sanongraj
Bulk and Material Density- Homeowner: the bulk density of MSW might be between 150 and 250 lb/yd3 (90 and 150 kg/m3)- MSW in the can: the bulk density of MSW might be at 300 lb/yd3 (180 kg/m3)- MSW in a collection truck that has a compactor: the bulk density of MSW might be between 600 and 700 lb/yd3 (350 and 420 kg/m3)- MSW in a landfill with covering soil: the bulk density of MSW might be between 700 and 1700 lb/yd3 (350 and 1000 kg/m3)
Table 2-8: Material Densities Commonly Found in Refuse (Vesilind et. al., 2002)
26 By Dr. Sompop Sanongraj
Because of the highly variable density, MSW quantities are seldom expressed in volumes and are almost always expressed in mass terms as either pounds or tons in the American standard system (ton = 2000 lb), or kilograms or tonnes in the SI system (tonne = 1000 kg).
Mechanical Properties
Figure 2-9: Compressive characteristics of some components of solid waste (Vesilind et. al., 2002)
27 By Dr. Sompop Sanongraj
Figure 2-10: Tensile Strength of Some Municipal Solid Waste Component (Vesilind et. al., 2002)
BiodegradabilityTable 2-9: Calculation of Biodegradable Fraction of MSW (Vesilind et. al., 2002)
28 By Dr. Sompop Sanongraj
Chapter3: Collection
Solid and Hazardous Waste Management
29 By Dr. Sompop Sanongraj
(Vesilind et. al., 2002)
Phase 1: House to Can
- Volume-based fee system:
- 30-, 60-, or 90- gallon (110-, 230-, and 340– liter) cans
- Home compactor: 20 lb (9kg) with compaction ratio about 1:5
- Weight-based fee system
30 By Dr. Sompop Sanongraj
Phase 2: Can to Truck
- Backyard collection
- Expensive in dollar cost to the community
- Extremely high injury rate to the collectors
- Curbside collectionTrucks Used for Residential and Commercial Refuse Collection
- Rear-loading Packer Truck: 16- and 20-yd3 (12- and 15-m3): compress the refuse from a loose density of about 100 to 200 lb/yd3 (60 to 120 kg/m3) to about to 600 to 700 lb/yd3 (360 to 420 kg/m3)
- Side-loading Packer Truck
31 By Dr. Sompop Sanongraj
3-(Vesilind et. al., 2002)
(Vesilind et. al., 2002)Figure 3-2: A rear-loading packer truck for collecting residential solid waste (Vesilind et. al., 2002)
Figure 3-3: Compacting mechanism for a packer truck (Vesilind et. al., 2002)
Figure 3-4: Slide-loading packer truck (Vesilind et al., 2002)
32 By Dr. Sompop Sanongraj
Figure 3-5: Recyclables, yard waste, and mixed refuse at the curb (Vesilind et. al., 2002)
Two Revolutionary Changes (1990)
- Green-can-on-wheels idea:
- Semi-automated Collecting Truck
- Fully automated Collecting Truck
- Plastic Bags
33 By Dr. Sompop Sanongraj
Figure 3-6: Green plastic container used for solid waste collection (Vesilind et. al., 2002)
Figure 3-7: Collection with vehicles equipped with can snatchers (Vesilind et. al., 2002)
34 By Dr. Sompop Sanongraj
Phase 3: Truck from House to House
As a rough guideline, for residential curbside collections, a single truck should be able to service between 700 and 1000 customers per day if the truck does not have to travel to the land fill. Realistically, most trucks can service only about 200 customers before the truck is full and a trip to the landfill isnecessary.
35 By Dr. Sompop Sanongraj
The total time in a workday can be estimated as:
Y = a + b + c(d) + e + f + g
where Y = the total time in a workday
a = time from the garage to the route, including the marshaling time, or that time needed to get ready to get moving
b = actual time collecting a load of refuse
c = number of loads collected during the working day
d = time to drive the fully loaded truck to the disposal facility, deposit the refuse, and return to the collection route
e = time to take the final, not always full, load to the disposal facility and garage
f = official breaks including time to go to the toilet
g = other lost time such as traffic jams, breakdowns, etc.
If the number of customers that a single truck can service during the day is known, the number of collection vehicles needed for acommunity can be estimated by
N = SF/XW
where N = number of collection vehicles needed
S = total number of customers serviced
F = collection frequency, number of collections per week
X = number of customers a single truck can service per day
W = number of workdays per week
36 By Dr. Sompop Sanongraj
Phase 4: Truck Routing
The routing of a vehicle within its assigned collection zone is often called micro-routing to distinguish it from the large-scale problems (phase 5) of routing to the disposal site and the establishment of the individual route boundaries. The latter problem is commonly known as macro-routing or districting.
Question: how to route a truck through a series of one- or two- way streets so that the total distance traveled is minimized?
Objective: to minimize deadheading, traveling without picking up refuse.
37 By Dr. Sompop Sanongraj
Question in 1736 about designing a route so as to eliminate all deadheading: How to design a route for a parade across the seven bridges of KÖnigsberg, a city in eastern Prussia, such that the parade would not cross the same bridge twice but would end at the starting point?
(Vesilind et. al., 2002)
DD
DB
Leonard Euler (the brilliant mathematician) not only proved that the assignment was impossible, but he generalized the two conditionsthat must be fulfilled for any network to make it possible to traverse a route without traveling twice over any road.
1. All points must be connected (one must be able to get from one place to another).
2. The number of links to any node must be of an even number (called a unicoursal network or Euler’s tour)
(Vesilind et. al., 2002)
38 By Dr. Sompop Sanongraj
Kwan (1962) has provided a means of achieving the most efficient unicoursal network (and also provided the name for this procedure: the Chinese postman problem) by observing that networks are really a series of loops where each node appears exactly once.
(Vesilind et. al., 2002)
Once a unicoursal network has been designed, the route for the truck through thisnetwork can be applied using the method of heuristic (commonsensical) routing as shown in the following set of rules:
1. Routes should not overlap, but should be compact and not be fragmented.
2. The starting point should be as close to the truck garage as possible.
3. Heavily traveled street should be avoided during rush hours.
4. One-way streets that cannot be traversed in one line should be looped from the upper end of the street.
5. Dead-end streets should be collected when on the right side of the street
6. On hills, collection should proceed downhill so that the truck can coast.
7. Clockwise turns around blocks should be used whenever possible.
8. Long, straight paths should be routed before looping clockwise.
9. For certain block patterns, standard paths, as shown in Figure 3-11, should be used.
10. U-turns can be avoided by never leaving one two-way street as the only access and exit to the node.
39 By Dr. Sompop Sanongraj
(Vesilind et. al., 2002)
(Vesilind et. al., 2002)
40 By Dr. Sompop Sanongraj
Phase 5: Truck to Disposal
For smaller isolated communities, the macro-routing reduces to one of finding the most direct road from the end of the route to the disposal site.
For regional systems or large metropolitan areas, the macro-routing in terms of developing the optimum disposal and transport scheme can be found using the available techniques, called allocation models.
Commercial Wastes
Figure 3-13: A dumpster used for commercial collection (Vesilind et. al., 2002)
Figure 3-14: Dumpster collection truck being emptied at a landfill (Vesilind et. al., 2002)
41 By Dr. Sompop Sanongraj
Transfer Stations
(Vesilind et. al., 2002)
Figure 3-15
Figure 3-16: Several typical transfer stations (a) dump to container (b) dump to trailer (c) store and dump to truck trailer (d) dump to compactor (Vesilind et. al., 2002)
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Collection of Recyclable Materials
Table 3-1: Collection of Recyclables, 1997 (Vesilind et. al., 2002)
(Vesilind et. al., 2002)Figure 3-17
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Figure 3-18: Multicompartments truck for collecting separated recyclable materials (Vesilind et. al., 2002)
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Chapter4: Processing of Municipal Solid Waste
Solid and Hazardous Waste Management
45 By Dr. Sompop Sanongraj
Refuse Physical Characteristics
- Particle Size: sieving
- Bulk Density: see Fig 4-1
- Angle of Repose: the angle of repose is the angle, to the horizontal, that the material will stack without sliding. For the shredded refuse, it varies from 45oto greater than 90o!!.
- Material Abrasiveness
- Moisture Content
(Vesilind et. al., 2002)Figure 4-1
46 By Dr. Sompop Sanongraj
Storing MSWTwo major considerations:
- Public health
- Fire
“For a safety of fire from a storage of MSW, the rule of thumb is that two days of storage.”
All storage facilities should be constructed as first-in/first-out.
Common storage systems:
- A pit with an overhead bridge crane
- A large tipping floor
The design of better storage facilities requires a knowledge of theory of material flow and a means of experimentally evaluating the flow rate of solid material in a storage chamber. A number of potentially effective techniques are stereophotogrammetry, radio pills (transmitters that move with the solids) etc.
ConveyingSix basic types of conveyors:(1) rubber-belted conveyors(2) live bottom feeders(3) pneumatic conveyors(4) vibratory feeders(5) screw feeders(6) drag chains
The first three types are used primarily to move refuse; the last three are used to feed or meter refuse to a load sensitive device such as a combustor.
47 By Dr. Sompop Sanongraj
Figure 4-2: Typical feed conveyor (Vesilind et. al., 2002)
48 By Dr. Sompop Sanongraj
Figure 4-3: Conveyer commonly used for MSW. (Vesilind et. al., 2002)
Table 4-1: Rubber Conveyor Belt Capacities for Selected Materials, at a Belt Speed of 100 ft/min (Vesilind et. al., 2002)
Figure 4-4 Typical live bottom (walking floor)
(Vesilind et. al., 2002).
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Pneumatic conveyor
(Vesilind et. al., 2002)Table 4-2
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Vibrating Feeder
4-5.
Figure 4-5: Screw conveyer (Note: Top screw has N = 1, and bottom screw has N = 2 (Vesilind et. al., 2002)
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4-1
Compacting
Drag Chain Conveyor
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Compacting (cont.)
m
v
s
v
v
s
m
vsm
VVn
is (n)porosity theandVVe
as defines is (e) ratio voidThe voidsof volumeV
moisture) the(including solids of volumeV material of volumeV where
VVV
=
=
===
+=
m
mb
b
w
s
m
wsm
VW
as defined is )(density bulk Themoisture of weight W
soilds of weight W moisture including material, of weight Wwhere
WWWor moisture, plus soilds the
ofupmadeismaterial totaleweight thBy
=ρ
ρ===+=
Compacting (cont.)
53 By Dr. Sompop Sanongraj
Compacting (cont.)
Figure 4-6
Figure 4-6: Compression curve for a sample of MSW in a laboratory. The rebound curves occur the compressive pressure is released. (Vesilind et. al., 2002)
54 By Dr. Sompop Sanongraj
ShreddingShredding is the generic term for size reduction. Shredding
encompasses all the processes used for making little particles out of big particles.
The shredded MSW has a more uniform particle size, is fairly homogeneous, and is compacted more readily than unshredded waste, mainly because the larger voids has been eliminated.
Use of Shredders in Solid Waste Processing
The first application of shredders is to facilitate disposal, with little consideration for materials recovery.
The second application is in the production of refuse-derived fuel (RDF).
The third application is in the processing of yard waste as well as demolition debris, branches, and other organic material to produce a mulch that can then be composted or used as a ground cover.
The fourth application is in the processing of material recovery.
Shredding (cont.)
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Type of Shredders Used for Solid Waste Processing
Hammermill: used for solid waste processing.- Horizontal hammermill- Vertical hammermill
Hog: used to shed green waste.Shear Shredders: used to slice whole tires prior
disposal.Flail: used to beat at the plastic bags and bottles.
Shredding (cont.)
Figure 4-7 Horizontal Hammermill Shredder (Vesilind et. al., 2002)
56 By Dr. Sompop Sanongraj
Figure 4-8 Vertical Hammermill Shredder (Vesilind et. al., 2002)
Figure 4-9 Inside a Vertical HammermillShredder (Vesilind et. al., 2002)
Figure 4-10 Hog (Vesilind et. al., 2002)
Figure 4-11 Hog Feed Conveyor (Vesilind et. al., 2002)
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Figure 4-12 Shear Shredder (Vesilind et. al., 2002)
(Vesilind et. al., 2002)Figure 4-13
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Figure 4-14 Cumulative Particle-size Distribution Curve (Vesilind et. al., 2002)
Figure 4-14,
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(Vesilind et. al., 2002)
Figure 4-15
Figure 4-15Table 4-3
(Vesilind et. al., 2002)Table 4-3:
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Figure 4-15
4-2
4-3
Figure 4-15
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Figure 4-16 Rosin-Rammer Paper for Floating Particle-Size Distribution (Vesilind et. al., 2002)
PulpingThe raw refuse is
pulped and all pulpableand friable materials are reduced in size so as to fit through the holes immediately below the cutting blade.
Figure 4-17 Pulper Used for Processing MSW (Vesilind et. al., 2002)
62 By Dr. Sompop Sanongraj
Roll Crushing Roll crushers are used in resource
recovery operations for the purpose of crushing brittle materials such as glass while merely flattening ductile materials such as metal cans-hence allowing for subsequent separation by screening.
GranulatingGranulators are used for some
materials, such as plastic bottles.
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Chapter5: Materials Separation
Solid and Hazardous Waste Management
64 By Dr. Sompop Sanongraj
Material recovery facilities (MRFs, pronounced “murphs”)
- Dirty MRFs: process mixed waste
- Clean MRFs: process partially separated material
Separation devices based on a principle of coding and switching:
- Coding: to find a recognition code obtained from some property of the materials to differentiate the materials
- Switching: to physically separates the materials using a recognition code
General Expressions for Material Separation
- Binary (two output streams): such as a magnet capturing ferrous material
- Polynary (more than two output streams): such as a screen with a series of different sized holes
Technical Terms:
Product or extract: materials that are separated from the waste stream.
Reject: materials that are not separated from the waste stream.
65 By Dr. Sompop Sanongraj
Schematic of Binary Separator
Binary Separator
1
2x0 + y0
x2 + y2
x1 + y1
Binary Separator
Effective of Separation- Recovery (R)- Purity (P)
210210
22
2y
11
1X
0
2y
0
1X
yyy and xx x:Note
100 yx
yP ;100 yx
xP
100 yyR ;100
xxR
21
21
+=+=
+
=
+
=
=
=
Schematic of Polynary Separator
PolynarySeparator
12
x0 + y0x2 + y2x1 + y1
Polynary Separator
m xm + ym
PolynarySeparator
12
x10 + x20+ … + xm0 m
x11 + x21+ … + xn1x12 + x22+ … + xn2
x1m + x2m+ … + xnm
66 By Dr. Sompop Sanongraj
Effective of Separation- Recovery (R)- Purity (P)
1m121110
1n2111
11X
10
11X
m210
11
1X
0
1X
x ... xx x:Note
100 x...xx
xP
100 xxR
x ... xx x:Note
100 yx
xP
100 xxR
11
11
1
1
+++=
+++
=
=
+++=
+
=
=
Example 5-1A binary separator has a feed rate of 1 ton/h. It is operated so that during any 1 hour, 600 kg reports as output1 and 400 kg as output2. Of the 600 kg the x constituent is 550 kg, while 70 kg of x end up in output2. Calculate the recovery and purity.
Solution:
( )
( ) %92100600550100
yxxP
%8810070550
550100 xxR
11
1X
0
1X
1
1
==
+
=
=+
=
=
67 By Dr. Sompop Sanongraj
Methods for the Separation of Materials from Waste- Picking (hand sorting)
- Positive sorting: to recover any items of value that need not to be processed.- Negative sorting: to remove all those items that could cause damage to the rest of the processing system.
- Screens- Trommel Screens- Reciprocating and Disc Screens
- Float/Sink Separators- Jigs- Air classifiers- Heavy-media separators- Upflow separators
Methods for the Separation of Materials from Waste (cont.)
- Magnets- Eddy Current Separators- Electrostatic Separators- Other devices
- Stoners- Inclined tables- Shaking tables- Optical sorting- Bounce and adherence separators
68 By Dr. Sompop Sanongraj
(Vesilind et. al., 2002)Figure 5-1
(Vesilind et. al., 2002)Figure 5-2
69 By Dr. Sompop Sanongraj
(Vesilind et. al., 2002)Figure 5-3 A common plunger jig. (Vesilind et. al., 2002)
(Vesilind et. al., 2002)Figure 5-4
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Figure 5-5
(Vesilind et. al., 2002)
(Vesilind et. al., 2002)Figure 5-6
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Figure 5-7 Triboelectric charging progression. (Courtesy Steinert) (Vesilind et. al., 2002)
Figure 5-8 Separation of triboelectrically charge plastic.(Courtesy Steinert) (Vesilind et. al., 2002)
72 By Dr. Sompop Sanongraj
Figure 5-9 Optical sorting. (Vesilind et. al., 2002)
Materials Separation Systems
In summary, there are three levels of engineering responsibility:
- Engineers who must understand the overall nature of the system, including the nature of the feedstock and the markets for the products.
- Engineers who must understand the system and how each unit operation is to perform within the materials recovery system.
- Engineers who must understand each unit operation and who must be careful to apply such equipment appropriately.
73 By Dr. Sompop Sanongraj
Figure 5-10 A typical dirty materials recovery facility for mixed waste (Vesilind et. al., 2002)
(Vesilind et. al., 2002)Figure 5-11
74 By Dr. Sompop Sanongraj
Figure 5-12 An alternative materials recovery facility for previously separated waste (Vesilind et. al., 2002)
Performance of Materials Recovery FacilitiesFor the Hasselriis system, it is based on the idea that each unit operation rejects some fraction of the feed and extracts the remaining, and that these fractions of reject and extract are the same regardless of where the unit operation is placed in the process train.
For example,
Feed Air classifier Trommel Reject
ExtractExtract
Define f as the split, or fraction of material rejected by any unit operation, and thus (1-f) is the fraction of material extracted by the unit operation.
75 By Dr. Sompop Sanongraj
5-2
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77 By Dr. Sompop Sanongraj
Chapter 6: Combustion and Energy Recovery
Solid and Hazardous Waste Management
78 By Dr. Sompop Sanongraj
Heat Value of Refuse- British thermal unit (BTU): an amount of energy necessary to heat one pound of water one degree Fahrenheit.
- Kilocalorie: an amount of energy necessary to heat one kilogram of water one degree Celsius.
- Joule
- Kilowatt-hour (kWh)
The amount of energy or heat value in an unknown fuel can be estimated by ultimate analysis, compositional analysis, proximate analysis, and calorimetry.
(Vesilind et. al., 2002)Table 6-1
79 By Dr. Sompop Sanongraj
Ultimate AnalysisUltimate analysis uses the chemical makeup of the fuel to approximate its heat value.
DuLong Equation (originally developed for estimating the heat value of coal):
ly.respective sulfur, and oxygen, hydrogen, carbon,of basis)(dry spercentage weight theare S and O, H, C, where
S40O81H620C145lb/Btu +
−+=
Another equation for estimating the heat value of refuse:
ly.respectivenitrogen and sulfur, oxygen, hydrogen, carbon,of basis)(dry spercentage weight theare N and S, O, H, C, where
N8.10S4.41O2.6H672C144lb/Btu −+++=
(Vesilind et. al., 2002)Table 6-2
80 By Dr. Sompop Sanongraj
Compositional AnalysisFormulas based on compositional analyses are an improvement over formulas based on ultimate analyses.
Using regression analysis and comparing the results to actual measurement of heat value, a compositional model:
basisdry on by weight percent water,W basisdry on by weight percent wastes,food G
basisdry on by weight percent paper, P basisdry on by weight percent plastics, R where
W7.20G7.2P4.4R6.151238lb/Btu
====
−+++=
Figure 6-3 Typical Heat Values of MSW Components (Vesilind et. al., 2002)
81 By Dr. Sompop Sanongraj
Table 6-4 Typical Moisture Contents of MSW (Vesilind et. al., 2002)
6-1
6-3
6-2
6-2
Example 6-2
As shown in Table 6-4,
82 By Dr. Sompop Sanongraj
Proximate AnalysisIn proximate analysis it is assumed that the fuel is composed of two types of materials: volatiles and fixed carbon.
C950 and C600between lost matter dry all offraction carbon, fixed B C600at lost matter dry all offraction , volatilesA where
14,500B8000ABtu/lb:equation analysis proximate usedcommonly A
oo
o
=
=
+=
Table 6-5 Typical Proximate Analysis of MSW Component (Vesilind et. al., 2002)
CalorimetryCalorimetry is the referee method of determining heat value of mixed fuels using a bomb calorimeter.
Figure 6-1 Bomb calorimeter used to measure heat value of a fuel (Vesilind et. al., 2002)
83 By Dr. Sompop Sanongraj
For a bomb calorimeter, a plot of temperature (T) versus time (t), is called a thermogram.
Figure 6-2 Temperature/time trace from a bomb calorimeter (Vesilind et. al., 2002)
Each calorimeter is different and must be standardized using a material for which the heat of combustion is known precisely.
84 By Dr. Sompop Sanongraj
6-3
6-4
Calorimetric Heat Value- The higher heating value (HHV), or the gross calorific energy: including the contribution due the latent heat of vaporization of water that has occurred in the bomb calorimeter.
-The lower heating value (LHV), or the net calorific energy: excluding the contribution due the latent heat of vaporization of water that has occurred in the bomb calorimeter.There are at least two reasons why the HHV number overestimates the actual heat value in combustion:
- The presence of metals:
- The incomplete combustion of organics: the amount of unburned organics can vary from 2% to 25%, depending on the effectiveness of the operation.
( ) heatOAl2O3Al4 322 +→+
85 By Dr. Sompop Sanongraj
Because MSW is such a heterogeneous and unpredictable fuel, engineers often need to have “rules of thumb” for estimating the heat values.
For MSW, one rule of thumb is that one ton of MSW produces 5000lb of stream, and this steam produces 500 kilowatts of electricity. (Vesilind et. al., 2002)
Materials and Thermal BalancesCombustion Air
The energy from the sun is stored, using the process of photosynthesis, in organic molecules, and this energy is released as the organic materials decompose.
( )
( ) energy heatOHCOOHC:organicsenergy -high theofn degradatio The
ns.hydrocarbo of variety infinitean represents (HC) thewhereOHCOHnutrientssunlightCO
:process esisphotosynth The
222x
x
2x22
++→+
+→+++
Combustion of the organic fraction of refuse is simply a very rapid decomposition process.
86 By Dr. Sompop Sanongraj
6-5
6-6Since the stoichiometric oxygen, from Example 6-5, is 4 g O2/g CH4, the stoichiometric air requirement is 4/0.2315 = 17.3 g air/g methane.
Materials and Thermal BalancesEfficiency
(Vesilind et. al., 2002)Figure 6-3
87 By Dr. Sompop Sanongraj
100INEnergy
dEnergy Use(E) Efficiency
WASTEDenergy
of Rate
USEDenergy
of Rate
INenergy
of Rate
OUTenergy
of Rate
INenergy
of Ratecondition state-steadyat balance Energy
×=
+
=
=
6-7
Thermal Balance on a Waste-to-Energy Combustor
Figure 6-4 Black box showing energy flow in a combustor (Vesilind et. al., 2002)
88 By Dr. Sompop Sanongraj
6-7
Two criteria that can be easily monitored, ensure complete combustion of the solid waste and recovery:
(1) ash must not exceed a percent combustible level.
(2) exhaust gas in the stack must be within a predetermined temperature range.
89 By Dr. Sompop Sanongraj
- Incinerators: refuse is burned without recovering energy
- Waste-to-energy combustor:
-modern combustors combine solid waste combustion with energy recovery (see Fig. 6-5, most refuse combustors operate in the range of 980 to 1090oC).
- the combustor with a modification of the combustion chamber (rotary kiln, see Fig. 6-6) and a modificcationof a furnace wall (water wall, Fig. 6-7).
- Modular starved air combustor (Fig. 6-8).
- Pyrolysis (gasification): it is destructive distillation, or combustion in the absence of oxygen.
Combustion Hardware Used for MSW
OHCHCCOHCH energy heatOHC 2222245106 +++++→+
Figure 6-5 A typical municipal solid waste combustor. (Vesilind et. al., 2002)
90 By Dr. Sompop Sanongraj
Figure 6-6 Rotary kiln (Vesilind et. al., 2002)
Figure 6-7 Water-wall tubes lining the furnace of an MSW combustor(Vesilind et. al., 2002)
91 By Dr. Sompop Sanongraj
Figure 6-8 Modular combustor (Vesilind et. al., 2002)
Mass Burn versus RDF
- A mass burn unit has no preprocessing of solid waste prior to being fed into the combustion unit.
- In a RDF system the solid waste is processed prior to combustion to remove noncombustible item and to reduce the size of the combustible fraction, thus producing a more uniform fuel at a higher heat value.
92 By Dr. Sompop Sanongraj
“RDF-6 and -7, have been tried on a pilot basis but have not been found t o be successful at full-scale plants”.
Table 6-6 ASTM Refuse-Derived Fuel Designations (Vesilind et. al., 2002)
- Waste Heat
- Ash
- Air Pollutants
Undesirable Effects of Combustion
93 By Dr. Sompop Sanongraj
Ash
Table 6-7 Materials Found in Typical MSW Ash (Vesilind et. al., 2002)
Ash
(Vesilind et. al., 2002)
Table 6-8 Total Metal in Combined Ash (Vesilind et. al., 2002)
94 By Dr. Sompop Sanongraj
Air Pollutants- Particulates
- Gases: CO, SO2, HC, NOx, Mercury vapor, Dioxin
95 By Dr. Sompop Sanongraj
Chapter7: Biochemical Processes
Solid and Hazardous Waste Management
96 By Dr. Sompop Sanongraj
Three components of MSW of greatest interest in the bioconversion processes:
- Food waste (garbage)
- Paper products
- Yard waste
(Vesilind et. al., 2002)Table 7-1
Biological Methods:- Digestion
- Anaerobic digestion (in the absence of oxygen)
- Aerobic digestion (with oxygen)
- Composting
- Others
- Enzyme hydrolysis (cellulose glucose)
- Acid hydrolysis (cellulose glucose)
- Other fermentation processes (eg. fungus can be used to convert cellulose to protein, and the production of ethanol by the fermentation of glucose.)
97 By Dr. Sompop Sanongraj
Methane Generation by Anaerobic Digestion
Ideally, the production of methane and carbon dioxide can be calculated using the following equation:
7-1
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Anaerobic DecompositionTwo groups of microorganisms responsible for anaerobic decomposition:
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CompostingFundamentals of CompostingThe basic aerobic decay equation is shown below:
Eq. 7-1
7-2
Table 7-2(Vesilind et. al., 2002)
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Design and Operational Considerations
Table 7-3 Important Design Considerations for Aerobic Composting Process(Tchobanoglous et. al., 1993)
Figure 7-1 Typical Temperature and pH Ranges Observed in Windrow Composting (Tchobanoglous et. al., 1993)
101 By Dr. Sompop Sanongraj
Table 7-4 EPA Requirements for Pathogen Control in Compost Processesa
Two-Step Operations in Composting:- The decomposition of complex molecules of waste materials into simpler entities.
- The synthesis of the breakdown products into new cells (a sufficient nitrogen supply is necessary).
A C/N of 20:1 is the ratio at which nitrogen is not limiting the rate of decomposition. Some researchers recommend an optimal C/N ratio of 25:1.
102 By Dr. Sompop Sanongraj
Table 7-5 Carbon/Nitrogen Ratios for Various Materials (Vesilind et. al., 2002)
7-2
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Moisture Content in Composting
7-3
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Eq. (7-1).
Fig. 7-1.
7-2,
7-2,7-2.
7-4).
105 By Dr. Sompop Sanongraj
7-4Example 7-4 Air requirements for in-vessel composting.Determine the amount of air required to compost one ton of solid wastes using an in-vessel composting system with forced aeration. Assume that the composition of the organic fraction of the MSW to be composed is given by C60.0H94.3O37.8N. Assume that the following conditions and data apply:
Air Requirements. In processes with forced aeration, such as the aerated static pile and the in-vessel system, The total air requirement and air flow rate are essential design parameters. Computation of the total air requirements and air flow rate for an in-vessel composting system is illustrated in Example 7-4. The computations for an aerated static pile system are similar.
as given belowซ
106 By Dr. Sompop Sanongraj
pHSee Figure 14-5. The pH value in a range of 7-8 in the mature compose. If the degree of aeration is not adequate, anaerobic condition will occur, the pH will drop to about 4.5, and the composting process will be retarded. The pH also affects nitrogen loss, because ammonia escapes as ammonium hydroxide above a pH of 7.0.
Degree of compositionThe time required for a compost pile to mature depends on such factors as the putrescence of the feed, the insulation and aeration provided, the C/N ratio, the particle size, and other conditions as mentioned.
Usually, two weeks is considered the minimum time for the adequate composting of shredded municipal refuse in windrows. Mechanical composting plants, using inoculation of previously composted materials, can accomplish decomposition in 2 or 3 days.
The completion of composting is judged primarily on the basis of a slight drop in temperature and a dark brown color. A more accurate measure is the determination of starch concentration in the compost. Starch is readily decomposable, and thus its disappearance is a good indicator of mature compost. A more rigorous measure of the end point is the drop in the C/N ratio to perhaps 12:1.
107 By Dr. Sompop Sanongraj
Other proposed methods for the measurement of the degree of decomposition:
(a) Final drop in temperature
(b) Degree of self-heating cappacity
(c) Rise in the redox potential
(d) Oxygen uptake
(e) Growth of the fungus: Chaetomium gracilis
(f) Analysis of chemical oxygen demand (COD) and the lignin test: a low COD value and a high lignin content (greater than 30 %) is indicative of a stable compost.
108 By Dr. Sompop Sanongraj
Land Requirements. Land area requirements are another important element which must be considered in the aerobic composting processes. For example, in windrow composting for a plant with acapacity of 50 ton/d, about 2.5 acres of land would be required (see Fig 7-2). Of this total, 1.5 acres would be devoted to buildings, plant equipment, and roads. For each additional 50 tons, it is estimated that 1.0 acre would be required for the composting operation andthat 0.25 acre would be required for buildings and roads. The land requirement for highly mechanized systems varies with the process. An estimate of 1.5 to 2.0 acres for a plant with capacity of 50 ton/d is not unreasonable; for larger plants, the unit area requirements would be less. For example, the Portland, Oregan, METRO compost plant, based on the DANO process, was designed to process 185,000 ton/yr of commingled MSW on an 18-acre site.
(Tchobanoglous et. al., 1993)
Figure 7-2
109 By Dr. Sompop Sanongraj
(Vesilind et. al., 2002)Figure 7-3
(Vesilind et. al., 2002)Figure 7-4
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(Tchobanoglous et. al., 1993)
Figure 7-5
(Vesilind et. al., 2002)Figure 7-6
111 By Dr. Sompop Sanongraj
(Vesilind et. al., 2002)Figure 7-7
(Vesilind et. al., 2002)Figure 7-8
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Chapter8: Sanitary Landfill
Solid and Hazardous Waste Management
113 By Dr. Sompop Sanongraj
Sanitary landfill vs. Secure landfill
Landfill classification
Classification Type of SW
1 2 3
Hazardous Designated MSW
(monofills)
Following landfill classes in Europe:
Landfills for Hazardous WasteLandfills for Non-Hazardous Waste (MSW)Landfills for Inert Waste (f.e. C+D Waste)
With the exception of inert waste all different kinds of waste have to be pretreated, in order to respect the requirements for elution.
EU-Landfill Regulation from 16. July 1999
114 By Dr. Sompop Sanongraj
Landfill Emissions
Dust, Noise, Insects, Rats, Birds
WastePrecipitation
Landfill gas
Ground water
Water Gaspollutants
Evaporation
Surface runoff
Leachate
Fundamentals of planning
Estimation of necessary capacities and classification of suitable site locations on the basis of local waste economy plans.Long-term prognosis resp. contracts for incoming waste in order to achieve investment resp.
Disposal costs per ton of MSW
115 By Dr. Sompop Sanongraj
Calculation of the landfill volume& operation periodDecision criteria:investmentssize of the suitable areaamount of waste in the disposal area
Decision criteria:equipment / constructionoperationaftercaredepreciation time
Volume
Operation Period
Landfill Setup
Entrance area,Control room
Scalehouse
Gas utilisation
Re-cultivation
Ring street
Fence
Gas-collection manifold
Fence
Groundwater control wellSurface water
collecting ditch
Leachate collection pipes
Base liner
Leachate Treatment
Figure 8-1 Schematic Diagram of a Landfill Setup (Bilitewski et al., 1997)
116 By Dr. Sompop Sanongraj
Daily cover 6-12”
compacted SW
cell-width(variable)
Final lift
Final cover
Final cell Bench
cell
cellcell
LF liner system
liftcell
height
Daily cover 6-12”
Daily cover 6-12”
Leachate collection
Gas pipe
Landfill Section
Technical Terms
•Daily Cover
•Cell
•Cell height
•Lift: Lift = cell height + daily cover height
•Bench or terrace
•Landfill liner system
•Final Lift
•Final cover
117 By Dr. Sompop Sanongraj
Technical Terms (continued)
•Leachate
•Landfill gases: CH4, CO2, H2S, NH3 etc.
•Landfill liner
•Monitoring well
•Landfill closure
Landfill Method1. Trench(excavated) method
2. Area method
3. Canyon
118 By Dr. Sompop Sanongraj
water table
Ground level
a) Trench(excavated) LF> 1.0 m
Soil (for daily cover)
Berm (earth embankment)
water tableGround level> 1.0 m
b) Area LF
Landfill siting consideration• Haul distance
• Location restrictions
•Available Land Area
• Site Access
• Soil Conditions and Topography
• Climatologic Conditions
• Surface Water Hydrology
• Geologic and hydrogeologic Conditions
• Local Environmental Conditions
• Ultimate Use of Completed Landfills
119 By Dr. Sompop Sanongraj
Location identification: Space and land utilisation planning
disposal site
human environment
noise emissions
dust emissions
living
using of the surrounding
land use
damage of protected property like groundwater, soil, air
odour emissions
visual impairment
EU General Requirements for all Classes of Landfills1. The location of the landfill must take in account:
-the distance from urban sites, residential areas, waterways, water bodies, agricultural sites-groundwater, coastal water natural protection zones-geological and hydrogeological conditions of the area -the risk o flooding, subsidence, avalanches-the natural and cultural patrimony of the area
2. All but inert landfill designs must assure water and leachate control in order to:-control water from precipitation or from surface or from ground entering into the landfill body-collect and treat leachate and contaminate water
3. Soil and water must be protected:-Geological barrier and bottom liner must be designed in order to prevent soil and groundwater pollution-Landfill base and sides must show low permeability in relation to landfill class
4. Produced gas must be controlled in order to: -avoid gas accumulation and migration -collect and use gas for producing energy, or flare it
5. Measures shall be taken to minimise nuisance and hazards like:-odour emission-wind blown materials-noise and traffic-birds and insects-fires
120 By Dr. Sompop Sanongraj
Generally, when siting a new landfill, developers should:1. Obtain the public involvement;2. Establish goals and gather political support;3. Identify facility design basis and need;4. Identify potential sites within the region;5. Select and evaluate in detail the most desirable sites;6. Select best site for development;7. Obtain regulatory site approval.
Site Search Process (USA)
Example 8-1 Estimation of required LF area for a community with a population of 31000. Assume that the following conditions apply:
1. SW = 6.4 lb/cap.d2. Compacted sp.wt. of SW in LF = 800 lb/yd3
3. Average depth of Compacted SW = 20 ftSolution:1. Determine daily SW generation rate = (31000 p)(6.4 lb/cap.d)
2000 lb/ton= 99.2 ton/d (88994 kg/d)
2. Volume required/d
= (99.2 t/d)(2000 lb/t)/(800 lb/yd3)= 248 yd3 /dArea required/yr = (248 yd3/d)(365d/yr)(27ft3/ yd3)
(20 ft)(43560 ft2/acre)= 2.81 acre/yr
Comment: The actual site requirements will be 20-40% greater than the value computed because additional land is required for a daily cover, slope, buffer zone, office bld. etc.
121 By Dr. Sompop Sanongraj
Composition& characteristics, generation, movement, and control of LF gas
Component %(dry volume)MethaneCarbon dioxideNitrogenOxygenSulfides,AmmoniaHydrogenCarbon monoxide
45-6040-602-50.1-1.00-1.00.1-1.00-0.20-0.2
Biodegradable org. in MSWOrganic waste component
Rapidly biodegradable
Slowly biodegradable
Lignin content, % of VS
Biodegradable Fraction, ,of VS
Food W. Newspaper Office paper Cardboard Plastic Textiles Rubber Leather Yard W. Wood
Y Y Y Y
Y(leave&grass)
Y Y Y
Y(woody) Y
0.4 21.9 0.4
12.9
4.1
0.82 0.22 0.82 0.47
0.72
(Tchobanoglous et. al., 1993)
122 By Dr. Sompop Sanongraj
Landfill Simulation Reactor (LSR)
0
50
100
150
200
250
0 50 100 150 200 250 300 350 400
gas
prod
uctio
n [l/
kg d
ry m
atte
r ]
cumulative gas production
pH -
valu
e
0
5
10
15
20
25
30
Con
duct
ivity
[mS/
cm]
pH - valueconductivity
9.0
8.0
7.0
6.
5.0
0
10000
20000
30000
40000
50000
BO
D5
, CO
D [m
g/l]
COD
BOD 5
0
500
1000
1500
2000
0 50 100 150 200 250 300 350 400time [d]
N to
tal,
NH
4-N
[mg/
l]
N totalNH4-N
0
50
100
150
200
250
0 50 100 150 200 250 300 350 400
gas
prod
uctio
n [l/
kg d
ry m
atte
r ]
cumulative gas production
0
50
100
150
200
250
0 50 100 150 200 250 300 350 400
gas
prod
uctio
n [l/
kg d
ry m
atte
r ]
cumulative gas production
pH -
valu
e
0
5
10
15
20
25
30
Con
duct
ivity
[mS/
cm]
pH - valueconductivity
9.0
8.0
7.0
6.
5.0
pH -
valu
e
0
5
10
15
20
25
30
Con
duct
ivity
[mS/
cm]
pH - valueconductivity
9.0
8.0
7.0
6.
5.0
0
10000
20000
30000
40000
50000
BO
D5
, CO
D [m
g/l]
COD
BOD 5
0
500
1000
1500
2000
0 50 100 150 200 250 300 350 400time [d]
N to
tal,
NH
4-N
[mg/
l]
N totalNH4-N
BMBF Statusbericht „Deponiekörper“, 1995
Landfill Gas Phases
BMBF Statusbericht „Deponiekörper“, 1995
Vol.%
I II III IV V
aero
bicac
id
initia
l
metha
noge
nic
stable
metha
noge
nic
long t
erm2 – 5 years several decades
123 By Dr. Sompop Sanongraj
Leachate Composition - Phases
BMBF Statusbericht „Deponiekörper“, 1995
Phase I II III IVV
Reactions in differnt landfill phases (1)
124 By Dr. Sompop Sanongraj
Reactions in different landfill phases (2)
Reactions in different landfill phases (3)
125 By Dr. Sompop Sanongraj
Reactions in different landfill phases (4)
Example 8-2 Estimate the chemical composition and amount of gasthat can be derived from the organic constituents in MSW. Determine the chemical composition and amount of gas that can be derived from the rapid and slowly decomposable organic constituents in MSW as given below (Assume 60% of the yard waste will decompose rapidly).
1. Set up a computation table to determine % of major elements composing the waste
CompositionComponent Wet wt .,lb
Dry wt .,lb C H O N S Ash
Rapid decomposable organic constituentsFWPaperCard b.YW
9.034.06.0
11.1
2.732.05.74.4
1.3013.922.512.10
0.171.920.340.26
1.0214.082.541.67
0.070.100.020.15
0.010.060.010.01
0.141.920.290.20
Total 60.1 44.8 19.83 2.69 19.31 0.34 0.09 2.55
126 By Dr. Sompop Sanongraj
CompositionComponent Wet wt .,lb Dry wt .,lb C H O N S AshSlowly decomposable organic constituents
TextilesRubberLeatherYWwood
2.00.50.57.42.0
1.80.50.43.01.6
0.990.390.241.430.79
0.120.050.030.180.10
0.56-
0.051.140.69
0.080.010.040.10
-
---
0.01
0.050.050.040.130.02
Total 12.4 7.3 3.84 0.48 2.44 0.23 0.01 0.292. Compute the molar composition of the element neglecting the ash
C H O N S
Lb/mole Total moles Rapidly decom. Slowly decom.
12.01
1.6511 0.3197
1.01
2.6634 0.4752
16.00
1.2069 0.1525
14.01
0.0241 0.0164
32.06
0.00280.0003
19.83 lb/ 12.01 lb/mole = 1.6511 mole
3. Determine an approximate chemical formula without S. Set up acomputation table to determine normalized mole ratios.
Mol.ratio(nitrogen=1) Component Rapidly decom. Slowly decom.
C H O N
68.5 110.5
50.1 1.0
19.5 29.0 9.2 1.0
The chemical formulas without S. are
Rapidly decom.= C68.5H110.5O50.1N (use C68H111O50N)
Slowly decom.= C19.5H29O9.2N (use C20H29O9N)
127 By Dr. Sompop Sanongraj
4. Estimate the amount of gas that can be derived from the rapidly and slowly decomposable organic constituents in MSW.
A) using the given equation
I) rapidly decomposable
CaHbOcNd +
0.25(4a-b-2c+3d) H2O
0.125(4a+b-2c-3d) CH4 +
0.125(4a-b+2c+3d) CO2 + d NH3 .. (11-2)
C68H111O50N +16H2O
1741 288
[0.125(4x68+111-2x50-3)= 35]CH4 + 33CO2 + NH3
560 1452 17
11CH4 + 9CO2 + NH3
176 396 17
C20H29O9N +9H2O
427 162
II) Slowly decomposable
B) Determine V of methane & carbon dioxide produced. The sp.wt. Of methane & carbon dioxide are 0.0448 and 0.1235 lb/cu.ft, respectively
I. Rapidly decomposable
methane = (560)(44.8) / (1741)(0.0448)= 321.7 cu.ft at STP
carbon dioxide = (1452)(44.8) / (1741)(0.1235) = 302 cu.ft at STP
II. Slowly decomposable
methane = (176)(7.3)/(427)(0.0448)= 67.2 cu.ft at STP
carbon dioxide = (396)(7.3)/(427)(0.1235) = 54.8 cu.ft at STP
C) Determine the total theoretical amount of gas generated per unit dry weight of org. matter destroyed.
I) Rapidly decomposable
Vol/lb = (321.7+302.5) / 44.8 = 13.9 ft3/lb
II) Slowly decomposable
Vol/lb = (67.2+54.8) / 7.3= 16.7 ft3/lb
128 By Dr. Sompop Sanongraj
0 5 10 15 20 YEAR
Gas production, ft3/yr15
10
5
Gas from rapidly in yr 5
Gas from slowly in yr 5
Total
Figure 8-2 Gas Production from Rapidly& Slowly Decomposable Org. in a LF (Tchobanoglous et. al., 1993)
0 5 10 15 20 YEAR
Gas production, ft3/yr15
10
5 Gas from LF with inadequate moisture
Figure 8-3 Effect of reduced moisture content on gas production from decomposable org. in a LF (Tchobanoglous et. al., 1993)
Gas from LF with adequate moisture
129 By Dr. Sompop Sanongraj
Control of Landfill Gases
• Passive Gas Control• Active Gas Control
In passive gas control systems, the pressure of the gas that is generated within the landfill serves as the drivng forces for the movement of the gas. In active gas control systems, energy in the form of an induced vacuum is used to control the flow of gas.
Active control of LF gas
Gas flareGas collection well
LF gas recovery using vertical wells
Blower
130 By Dr. Sompop Sanongraj
Blower/ flared station
LF gas header
Extraction well
LF perimeter
Radius of influence
X= 2r cos 300
Equilateral triangular distribution for vertical gas extraction wells
Water Balance in Landfill
(Tchobanoglous et. al., 1993)
Figure 8-4
131 By Dr. Sompop Sanongraj
LeachateNew LF(10y)
BOD COD TSS Org-N NH4-N NO3 TP pH
2000-30000 3000-60000
200-2000 10-800 10-800 5-40 5-100 4.5-7.5
10000 18000
500 200 200
25 30 6
100-200 100-500 100-400 80-120 20-40 5-10 5-10
6.6-7.5 (unit-mg/L except pH)
132 By Dr. Sompop Sanongraj
Liner systems for MSWto minimize infiltration of leachate into subsurface soil below LF thus eliminating potential for GW contamination. Some of the many types of liner designs are illustrated in Figure 8-5.
Control of leachate in LF
SW
Protective soil 30 cm.
Compacted clay 60 cm. (k
Not less than 30 cm.
Not less than 1 m.
Figure 8-6 Geosynthetic membrane installation
Geosynthetic membrane
BermNot less than 60 cm.
SW
Landfill
Leakage Through Clay Liner
K = 1x10-9 m/sClay
60 cm
Water 30 cm
Darcy’s law
Q = -KAI
K = hydraulic conductivity or permeability coefficient = 1x10-9 m/s
I = hydraulics gradient (the rate at which head changes with the distance) = -(0.3+0.6)/0.6=1.5
A = area of flow = 1 Rai = 1600 m2
Q = -(1x10-9 m/s)(-1.5)(1600 m2) = 2.4 x10-6 m3/rai /s
= 0.21 m3/rai /d = 76 m3/rai /y
134 By Dr. Sompop Sanongraj
Leachate Collection System
GeotextileOverlap
Perforated PipeRoundedrock or gravel
Geotextile
Liner
Sand DrainageLayer
Protective soilLayer
Clay
SW SW
Leachate Management Options
1) Leachate recycling
2) Leachate evaporation
3) Treatment + disposal
4) Discharge to municipal wastewater collection systems
135 By Dr. Sompop Sanongraj
Surface Water ManagementSurface water control systems: manage all surface waters including rainfall, stormwater runoff, intermittent streams, and artesian springs.
Cell 1 :during fillingClay berm
leachate
To storm water basin
Cell 2Cell 3
Pipe end capped after finishing a cover.
Ex. 8-3 Determine waste to soil ratio(cover material) by volume as a function of the initial compacted sp.wt. For a SW stream of 70ton per day to be place in 10 ft lifts with a cell width of 15 ft. The slope of working face is 3:1. Assume the waste is compacted initially to an average sp.wt. Of 600, 800 and 1000 lb/yd3. The daily cover thickness is 6 in.Solution:1. Determine the daily volume of the deposited SWa) For 600 lb/yd3
Vd = 70 ton/d x 2000 lb/ton x 1 yd3/ 600 lb = 233.3 yd3/ db) For 800 lb/yd3
Vd = 70 ton/d x 2000 lb/ton x 1 yd3/ 800 lb = 175 yd3/ d
136 By Dr. Sompop Sanongraj
c) For 1000 lb/yd3
Vd = 70 ton/d x 2000 lb/ton x 1 yd3/ 1000 lb = 140 yd3/ d
2. Determine the length of each daily cella) For 600 lb/yd3
L = (233.3 yd3/ d)(27 ft3/ yd3) / (10 ft)(15ft)= 41.9 ftb) For 800 lb/yd3
L = (175 yd3/ d)(27 ft3/ yd3) / (10 ft)(15ft)= 31.5 ftc) For 1000 lb/yd3
L = (140 yd3/ d)(27 ft3/ yd3) / (10 ft)(15ft)= 25.2 ft
CELL4
CELL1 CELL2
CELL3
Lift = 10ft W=
15ft
L
At
As
Af
Schematic of SW Cells
137 By Dr. Sompop Sanongraj
3. Determine surface areas
For 600 lb/yd3
section area = (h)(W)= 10x15 = 150 ft2
L = vol. / section area
= 233.3 x 27 / 150 = 41.9 ft
a) Top area = (L)(W) = 41.9x15 = 628.5 ft2
b) True Face area = (L)(T) = 41.9x31.6 = 1325 ft2
c) True Side area = (W) (T) = 15 x31.6 = 474 ft2
4. Determine volume of soil for daily cover
Vc = 6 in x (1/12ft)(At+Af+As)
Vc600 = 6 in x (1/12ft)(628.5+1325+474ft2) = 1214 ft3
Vc800 = 971 ft3
Vc1000 = 825 ft3
5. Determine the ratio of waste to cover soil
a) For 600 lb/yd3
Rw:c = (233.3 yd3x 27 ft3/ yd3) / 1214 ft3 = 5.19: 1
b) For 800 lb/yd3
Rw:c = 4.87 : 1
c) For 600 lb/yd3
Rw:c = 4.58 : 1
138 By Dr. Sompop Sanongraj
Closure of Landfills
Development of a closure plan
• Final cover design
• Surface water & drainage control systems
• Control of LF gas
• Control & treatment of leachate
• Environmental monitoring systems
Final Cover Layers
1) minimize infiltration from rainfall after LF completed
2) limit the uncontrolled release of LF gas
3) suppress the proliferation of vectors
4) limit the potential for fires
5) provide a suitable surface for vegetation
6) serve as the central element in the reclamation of the site
139 By Dr. Sompop Sanongraj
45 cm. topsoil
45 cm. Compacted clay k < 10-7cm/s
30 cm. soil subbase
15 cm. daily cover
SW
Final Cover
Figure 8-7 Final Cover for Clay Liner LF
Figure 8-8 Final Cover for Geomembrane Liner LF
60 cm. topsoil
30 cm. soil subbase
15 cm. daily cover
SW
1 mm HDPE
Final Cover (cont.)
140 By Dr. Sompop Sanongraj
Layout & preliminary design of LFLayout & preliminary design of LF
Layout of LF site:Layout of LF site:1. Access roads1. Access roads2. Equipment shelter2. Equipment shelter3. Scale3. Scale4. Office space4. Office space5. Location of convenience TS5. Location of convenience TS6. Storage and/or disposal sites for special wastes6. Storage and/or disposal sites for special wastes7. Areas to be used for waste processing(e.g. composting)7. Areas to be used for waste processing(e.g. composting)8. Definition of the LF areas and areas for stockpiling cover m8. Definition of the LF areas and areas for stockpiling cover materialaterial9. Drainage facilities9. Drainage facilities10. Location of LF gas10. Location of LF gas11. Location of 11. Location of leachateleachate treatment facilitiestreatment facilities12. Location of monitoring well12. Location of monitoring well13. Planting13. Planting
Property line
Fence
discharge
Drainage ditch
Monitoring well
Road
Figure 8-9 Plan View of Completed LF (closure& postclosure care)
Gas flaring station
GW flow
LeachateTreatment
Facility
141 By Dr. Sompop Sanongraj
Entrance Area
Figure 8-10 Landfill Entrance Station (Germany)
Buffer zone
LF
1 4 14 5 1m
grass
Plant
property line
Ditch
road 6 m
Not less than 25 m. from a property line
142 By Dr. Sompop Sanongraj
Landfill Gas Monitoring
At least 4 samples outside building twice a yearAt least 1 sample inside building twice a yearUpper Explosive Limit (UEL)= 15% methaneLower Explosive Limit (LEL)= 5% methaneMay not exceed LEL at property boundaryMay not exceed 1.25% methane(25%LEL) in the building
Surface water and Groundwater Monitoring • Take surface water, groundwater, leachate, and effluent from wastewater treatment samples at least twice a year.
• For groundwater samples, there are at least 3 monitoring wells ( 2 wells for downgradient and 1 well for upgradient).
• For surface water samples, there is at least one sample for each stagnant, upstream and downstream.
143 By Dr. Sompop Sanongraj
Environmental monitoring system
Water
Air
Soil
- land surface settlement
- Soil slippage
- Land surface erosion
Recultivation ExampleAfter covering the waste with a HDPE-liner, the recultivation layer has to be constructed
First step: compacted subsoil layer
Second step: topsoil layer
Source: Quelle, Trinekens
144 By Dr. Sompop Sanongraj
Recultivation and Aftercare
Figure 8-11 Completed LF (Germany)
Figure 8-12 Golf Course on a Landfill (Los Angeles)
145 By Dr. Sompop Sanongraj
Figure 8-13 Landfill Turned into a Park (Berlin)
Concept for Closed Landfills
Reduction of emission potential– water addition/ re-circulation (only for lined landfills)– in-situ aeration
Reduction of emissions– surface capping for minimizing leachate production– passive aeration for avoiding methane emissions
Low long term maintenance– alternative surface cap– leachate treatment using “natural“ systems (f.e. lagoons,
wetlands) or co-treatment with sewage
146 By Dr. Sompop Sanongraj
Aftercare Phase Surface cappingpassive Aerobisation
Operation Phase
Reactor LandfillsLeachate treatment
Gasutilisation
MBP-Landfilling
incineration
Bottom AshLandfillinglow gasproduction
Post operation phase
In situ aeration / Water addition
Mech.- biol.Pretreatment
Sustainable Landfill
Sustainable Landfill Concept
147 By Dr. Sompop Sanongraj
Chapter9: Hazardous Waste
Solid and Hazardous Waste Management
148 By Dr. Sompop Sanongraj
Hazardous Waste“Any waste or combination of wastes that poses a substantial danger, now or in the future, to human, plant, or animal life and that therefore must be handled or disposed of with special precaution (Davis and Masten, 2004”
EPA designates a waste to be hazardous in two ways: (1) by its presence on EPA developed lists (40 CFR
260, 1989).(2) by evidence that the waste exhibits ignitable,
corrosive, reactive, toxic, or leachablecharacteristics.
The list of hazardous waste (EPA’S hazardous waste code, 40 CFR 260):Code F: specific types of wastes from nonspecific sources; examples include spent halogenated and nonhalogenated solvents, electroplating sludges, and cyanide solutions from plating batches.Code K: specific types of wastes from specific sources; examplesinclude brine purification muds from the mercury cell process in clorine production where separated.Code P: any commercial chemical product or intermediate, off-specification product, or residue that has been identified as an acute hazardous waste; examples include potassium silver cyanide, toxaphene, and arsenic oxide.Code U: any commercial chemical product or intermediate, off-specification product, or residue that has been identified ashazardous waste; examples include xylene, DDT, CCl4 etc.Code D: characteristic wastes, which are not specifically identified elsewhere, that exhibit properties of ignitability, corrosivity, reactivity, or toxicity. TCLP (Toxic Characteristic LeachableProcedure) test need to be run.
149 By Dr. Sompop Sanongraj
Cradle-to-Grave ConceptThe cradle-to-grave hazardous waste management system is an attempt to track hazardous waste from its generation point (the “cradle”) to its ultimate disposal point (the “grave”). The system requires:
Generator requirements
Transporter regulations
Treatment, storage, and disposal requirements
Figure 9-1 Hazardous Waste Management System (UNEP Technical Report No. 17)
150 By Dr. Sompop Sanongraj
Hazardous Waste ManagementWaste minimization
Waste audit (“why is this waste being generated?”)
Waste reduction
Waste exchange
Recycling
Typical Treatment TechnologiesPhysical/Chemical
FiltrationFlocculationFlotationSedimentationSolidificationNeutralizationOil/water separationOxidationPrecipitationReduction, etc.
BiologicalActivated sludgeCompostingDigestionEnzyme treatmentTrickling filter, etc.
Pretreatment of bulk solids of tarsCrushing/grindingCryogenics
Dissolution
151 By Dr. Sompop Sanongraj
Figure 9-2 Recommended Treatement and Disposal of Industrial Wastes (UNEP Technical Report No. 17)
Table 9-1 Disposal technologies for industrial wastes
152 By Dr. Sompop Sanongraj
Stabilization/solidification is a technology where a waste material is mixed with materials that tend to set into a solid, thus capturing or fixing the waste within the solid structure.
Objective of stabilization/solidification:
To convert toxic waste streams into an
inert, physically stable mass, having very low leachability and with sufficient mechanical strength
to allow for land reclamation or landfilling.
Stabilization/Solidification
Figure 9-3 Stabilization/Solidification of Hazardous Waste (Batstone, R.; Smith, J.E.; Wilson, D., 1989)
Stabilization/Solidification
153 By Dr. Sompop Sanongraj
Figure 9-4 Hazardous Waste Landfill with Roof (Hünxe, Germany)
Figure 9-5 Deep Mine Landfill Herfa-Neurode(Germany)
154 By Dr. Sompop Sanongraj
Figure 9-6 Landfill Herfa-Neurode (Germany)
Figure 9-7 Bringing Up Walls in the Underground Disposal Facility Herfa-Neurode (Germany)
155 By Dr. Sompop Sanongraj
ABB Umwelttechnik GmbH, Butzbach
1. Solid waste2. Barrels3. Front wall with burner an injection for
fuids and pasty substances4. Rotary kiln5. VORTEX-Afterburner with injection6. Slag removal7. Secondary air
8. Boiler9. Electrostatic precipitator10. Fly ash transportation11. Radial scrubber12. Absorber13. Compressor14. Stack
Figure 9-8 Cross Section of a Hazardous Waste Incineration Plant (ABB Umwelttechnik GmbH, Butzbach)
Figure 9-9 Hazardous Waste Incineration Plant AVG-Hamburg (Germany)
156 By Dr. Sompop Sanongraj
Treatment Technologies for Remediation of Contaminated Site
Thermal, Physical, and Chemical Technologies
Thermal desorption
Soil flushing and surfactant enhancement
Soil washing and solvent extraction
Chemical oxidation
Bioremediation Technologies
Solid-phase bioremediation
Bioslurping
Enhanced in situ groundwater remediation
Examples of EPA’s Innovative Treatment Technologies for Site Remediation
Monitored Natural Attenuation (MNA)
NAPL (nonaqueous phase liquid) Recovery
Dynamic underground stripping
Six-phase heating
Bioslurping
Gravity
Surfactant and cosolvent flushing
157 By Dr. Sompop Sanongraj
Examples of EPA’s Innovative Treatment Technologies (cont.)
Passive treatment walls
Soil vapor extraction (SVE) with enhancements
Bioventing
Phytoremediation
Soil washing
Solvent extraction
In-situ oxidation
Enhance in-situ bioremediation of groundwater
Figure 9-10 Bioslurping (EPA Technical Report)
1
2
3
4
5
6
7
Vapour, water, oil
Gas
Groundwater
Water, oil
AirThermal gas treatment
Oil tank
Pond
Activatedcarbon filter
Water
Oil
1. Liquid separator2. Drop separator3. Oil-Water-Separator
158 By Dr. Sompop Sanongraj
Figure 9-11 Passive Treatment Walls (EPA Technical Report)
4 Compressor 5 Air cleaning
1 Water separator 2 Dust collector3 Priming cock (water purification)
12
3
4
5
Air Injection
Insaturated area
Saturated Area
Pollutant
Vacuum well
Injection well
Sealing
Gravel filter
Figure 9-12 Injection of Compressed Air in Combinationwith Soil Vapor Extraction (EPA Technical Report)
159 By Dr. Sompop Sanongraj
Blower and pressure tank
Air extraction and activated carbon filter
Figure 9-13 Bioventing (EPA Technical Report)
Figure 9-14 Phytoremediation (EPA Technical Report)
160 By Dr. Sompop Sanongraj
Figure 9-15 Soil washing (EPA Technical Report)
Figure 9-16 High Pressure Soil Washing (Klöckner Umwelttechnik)
161 By Dr. Sompop Sanongraj
Figure 9-17 Example: Solvent Extraction of Actinides Using TODGA (www.jaeri.go.jp/english/ press/000808/fig01.html)
Figure 9-18 Solvent Extraction (EPA Technical Report)
162 By Dr. Sompop Sanongraj
Figure 9-19 Enhanced in Situ Groundwater Remediation(EPA Technical Report)
Figure 9-20 Pump & Treat Process (EPA Technical Report)
Grundwasserbehandlung
Schlämme
Sauerstoff Nähstoffe
Grundwasserstauer
Groundwater treatmentNutrientsOxygen
Sludges
Base of aquifer
163 By Dr. Sompop Sanongraj
Homework and Solutions
164 By Dr. Sompop Sanongraj
AdministratorRectangle
AdministratorNoteRejected set by Administrator
Home work 1
1.1. จงอธิบายหลักการของการจดัการแบบ Integrated Solid Waste Management ที่ทาง EPA แนะนํามาพอสังเขป 1.2. จงยกตวัอยางผลิตภัณฑที่ทาํดวยพลาสติก มาอยางนอย 5 อยาง พรอมทั้งบอกประเภทของพลาสติก 1.3. จงอธิบายหลักการและวัตถุประสงคของการทํา Quartering and Coning 1.4. จากขอมูลของขยะมูลฝอยของชุมชนแหงหนึ่งแสดงดังตารางขางลางดังตอไปนี ้
Composition % by weight Moisture % by weight
Loose Density, kg/m3
Energy, BTU/kg
Food 50 70 220 900paper 20 6 80 3100Plastic 20 2 50 6300Glass 10 2 190 30
ก. จงหาความหนาแนนรวม (bulk density) ของตัวอยางขยะนี ้ข. จงหาเปอรเซน็ตความชื้นรวม (%moisture content) ของตัวอยางขยะนี้ โดยคิดบน
พื้นฐานของน้าํหนักเปยก (based on wet basis) ค. จงหาคา the moisture-free heat value ของตัวอยางขยะนี ้ง. ถาชุมชนดังกลาวมีประชากร 10,000 คน และปริมาตรขยะที่เกดิขึ้นทั้งหมดตอวันเทากับ
80 ลบ.ม. จงหาอัตราการผลิตขยะตอคนตอวัน จ. ถาชุมชนดังกลาวมีรถเก็บขยะที่มีปริมาตรบรรจุขยะเทากับ 12 ลบ.ม. ดวยสัดสวนการบอัด
ขยะเทากับ 1:4 จํานวน 1 คัน จงหาจํานวนเที่ยวในการทํางานเก็บขยะตอวนั กําหนดใหรถเก็บขยะสามารถบรรจุขยะไดเต็มที่ตามปริมาตรที่รองรับได โดยไมตองคํานึงถึงภาระบรรทุกที่กําหนดของถนน
1.5. จากขอมูลการวิเคราะหขนาดเสนผาศูนยกลาง (Diameter) ของอนุภาค (Particle) สําหรับตัวอยางหนึ่งมีรายละเอียดดังตอไปนี้
Particle diameter, mm 60 40 20 5 Weight of each fraction, kg 2 10 5 4 Number of particles 140 300 1000 2000 จงคํานวณหา คาขนาดเสนผาศูนยกลางของอนุภาคสําหรบัตัวอยางดังกลาวแบบ Arithmetic mean, Geometric mean, Weighted mean, Number mean, Surface area mean, and Volume mean
165 By Dr. Sompop Sanongraj
Home work 2
2.1. จงอธิบายองคประกอบของเวลาสวนตางๆที่ใชประเมินเวลาทั้งหมดในการทํางานเก็บขยะในแตละวัน 2.2. จากรูปขางลาง จงรางเสนทางการเก็บขยะโดยใชหลักของ Heuristic (Commonsensical) Routing Method หมายเหต ุถนนเปนแบบสองเลนสวนกนัไมมีเกาะกลาง โดยขับรถชิดดานซาย (ระบบการขับรถที่ใชในประเทศไทย)
2.3. การเก็บรวบรวมขยะมูลฝอยแบงหลักๆ ออกเปน 5 สวน (5 phases) ไดแก อะไรบาง จงอธิบายพอสังเขป 2.4. ชุมชนแหงหนึง่ มีบานจํานวน 1,000 หลัง แตละหลังมกีารทิ้งขยะ 28 กิโลกรัมตอสัปดาห ซ่ึงมีการเก็บขยะดังกลาวสัปดาหละครั้ง กําหนดให ความหนาแนนเฉลี่ยของขยะ เทากับ 150 กิโลกรัมตอลบ. เมตร จงคํานวณหา:
a. ปริมาตรของถังขยะอยางนอยที่ควรมีสําหรับแตบาน b. จํานวนรถเก็บขยะที่ตองการ ถาใชรถเก็บขยะขนาดบรรจ ุ5 ลบ.ม. ประเภทที่มี
เครื่องบีบอัด (compactor) ซ่ึงมีอัตราสวนการบีบอัด (compaction ratio) เทากับ 1:4 โดยทํางานสัปดาหละ 5 วัน
170 By Dr. Sompop Sanongraj
Home work 3
3.1. จากขอมูลการเก็บตัวอยางขยะมูลฝอยปริมาตร 1 m3 ของชุมชน แหงหนึ่ง มีองคประกอบแสดงดังตารางขางลางดังตอไปนี ้
Composition Weight (including moisture),
kg
Density (including
moisture) , kg/m3 Food (mixed organic waste) 80 250 paper 20 200 Plastic 5 50 Glass 2 2000 Other 1 1000
a. จงหาความหนาแนนรวม (bulk density) ของตัวอยางขยะนี ้b. จงหา void ratio (e) c. จงหาคา porosity (n) d. ถามีการบดอัดขยะดังกลาว ทําใหคา void ratio ลดลง 80 เปอรเซ็นต อยากทราบวาความหนาแนนรวมของขยะเพิ่มขึน้กี่เปอรเซ็นต
3.2. จงบอกความหมาย ของ characteristic size คืออะไร จากรูปขางลาง characteristic size ของตัวอยางนี้มีขนาดเทาใด กําหนดใหแกน x มีหนวยเปน mm
3.3. จงยกตวัอยางกระบวนการจดัการขยะมูลฝอย (Processing of Municipal Solid Waste) โดยเลือกมา 2 กระบวนการ พรอมทั้งอธิบายความสําคัญของแตละกระบวนการมาพอสังเขป 3.4. การเลือกอุปกรณที่ใชสําหรบัแยกวัสดุ มห