solid and hazardous waste management202.28.49.89/f20091106sompop46.pdf · 2015. 8. 13. · solid...

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)


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”


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 ”


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


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)


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)


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


Chapter2: Municipal Solid Waste (MSW) Characteristics and

Quantities

2-



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)


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%


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).


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.


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)


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)


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)


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)


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)


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)


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)


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:


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


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)


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).


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)


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)


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)


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)


Chapter3: Collection



(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


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


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)


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


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)


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.


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


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.


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?


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)



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.


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.


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)


Transfer Stations


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)


Collection of Recyclable Materials

Table 3-1: Collection of Recyclables, 1997 (Vesilind et. al., 2002)

(Vesilind et. al., 2002)Figure 3-17


Figure 3-18: Multicompartments truck for collecting separated recyclable materials (Vesilind et. al., 2002)


Chapter4: Processing of Municipal Solid Waste



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



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.


Figure 4-2: Typical feed conveyor (Vesilind et. al., 2002)


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).


Pneumatic conveyor

(Vesilind et. al., 2002)Table 4-2


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)


4-1

Compacting

Drag Chain Conveyor


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.)


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)


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.)


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)


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)


Figure 4-12 Shear Shredder (Vesilind et. al., 2002)



Figure 4-14 Cumulative Particle-size Distribution Curve (Vesilind et. al., 2002)

Figure 4-14,



Figure 4-15

Figure 4-15Table 4-3

(Vesilind et. al., 2002)Table 4-3:


Figure 4-15

4-2

4-3

Figure 4-15


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)


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.


Chapter5: Materials Separation



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.


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


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

==

+

=

=+

=

=


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


(Vesilind et. al., 2002)Figure 5-3 A common plunger jig. (Vesilind et. al., 2002)



Figure 5-5




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)


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.


Figure 5-10 A typical dirty materials recovery facility for mixed waste (Vesilind et. al., 2002)



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.


5-2


Chapter 6: Combustion and Energy Recovery



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.



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 −+++=



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)


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,


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)


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.


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 +→+


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.


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



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)


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.


- 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)


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)


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.


“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


Ash

Table 6-7 Materials Found in Typical MSW Ash (Vesilind et. al., 2002)

Ash


Table 6-8 Total Metal in Combined Ash (Vesilind et. al., 2002)


Air Pollutants- Particulates

- Gases: CO, SO2, HC, NOx, Mercury vapor, Dioxin


Chapter7: Biochemical Processes



Three components of MSW of greatest interest in the bioconversion processes:

- Food waste (garbage)

- Paper products

- Yard waste


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.)


Methane Generation by Anaerobic Digestion

Ideally, the production of methane and carbon dioxide can be calculated using the following equation:

7-1


Anaerobic DecompositionTwo groups of microorganisms responsible for anaerobic decomposition:


CompostingFundamentals of CompostingThe basic aerobic decay equation is shown below:

Eq. 7-1

7-2

Table 7-2(Vesilind et. al., 2002)


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)


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.


Table 7-5 Carbon/Nitrogen Ratios for Various Materials (Vesilind et. al., 2002)

7-2


Moisture Content in Composting

7-3


Eq. (7-1).

Fig. 7-1.

7-2,

7-2,7-2.

7-4).


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


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.


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.


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



Figure 7-5



Chapter8: Sanitary Landfill



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


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


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)


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


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


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


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


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.


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



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 ]


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 ]


pH -

valu

e

0

5

10

15

20

25

30

Con

duct

ivity

[mS/

cm]


9.0

8.0

7.0

6.

5.0

pH -

valu

e

0

5

10

15

20

25

30

Con

duct

ivity

[mS/

cm]


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


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


Leachate Composition - Phases


Phase I II III IVV

Reactions in differnt landfill phases (1)


Reactions in different landfill phases (2)




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


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)


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


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


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


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


Figure 8-4


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)


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


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


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


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


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


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


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.)


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


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


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.


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


Recultivation and Aftercare

Figure 8-11 Completed LF (Germany)

Figure 8-12 Golf Course on a Landfill (Los Angeles)


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


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


Chapter9: Hazardous Waste



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.


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)


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


Figure 9-2 Recommended Treatement and Disposal of Industrial Wastes (UNEP Technical Report No. 17)

Table 9-1 Disposal technologies for industrial wastes


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


Figure 9-4 Hazardous Waste Landfill with Roof (Hünxe, Germany)

Figure 9-5 Deep Mine Landfill Herfa-Neurode(Germany)


Figure 9-6 Landfill Herfa-Neurode (Germany)

Figure 9-7 Bringing Up Walls in the Underground Disposal Facility Herfa-Neurode (Germany)


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)


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


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


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)


Blower and pressure tank

Air extraction and activated carbon filter

Figure 9-13 Bioventing (EPA Technical Report)

Figure 9-14 Phytoremediation (EPA Technical Report)


Figure 9-15 Soil washing (EPA Technical Report)

Figure 9-16 High Pressure Soil Washing (Klöckner Umwelttechnik)


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)


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


Homework and Solutions


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


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


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

solid and hazardous waste management202.28.49.89/f20091106sompop46.pdf · 2015. 8. 13. · solid...

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