Chapter Solid Waste

7/28/2019 Chapter Solid Waste

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SOLID WASTE

MANAGEMENT


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SECTION 1 SOLID WASTE: TYPES, SOURCES AND

PROPERTIES

Learning Objectives;At the end of this lesson, students should be able to;

1. define solid waste

2. describe different types of solid wastes

3. recognize different sources of solid wastes

4. understand and state the three physical, chemical

and biological properties of solid waste


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WHY THIS HAPPENS?


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Sol id wastesare the wastes arising from human activities and are

normally solid as opposed to liquid or gaseous and are discarded as

useless or unwanted. Focused on urban waste (MSW) as opposed to

agricultural, mining and industrial wastes.

Integrated Solid Waste Management (ISWM)is the term applied to all

the activities associated with the management of society's wastes.

In medieval times, wastes discarded in the streets led to the breeding

of rats and the associated fleas which carried the plague.

22 human diseases are associated to improper solid wastemanagement.

Solid wastes also have a great potential to pollute the air, soil and water.

Materials Flow - The best way to reduce solid wastes is not to create

them in the first place. Others methods include: decrease consumption

of raw material and increase the rate of recovery of waste materials.

Technological advances - Increased use of recycle materials.

INTRODUCTION


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SOLID WASTE MANAGEMENT

Solid waste management is the control of :

all the wastes arising from human and animal activities that

are normally solid and that are discarded as useless andunwanted.

storage, management of wastes until they are put into a

container

collection, gathering of solid wastes and recyclable materials

and the transport of these materials where the collection

vehicle is emptied. 50% or higher of the total cost.

processing, source separated (at the home) vs. commingled

(everything together) is a big issue. Includes: physical

processes such as shredding and screening, removal of bulky

material, and chemical and biological processes such as

incineration and composting.

transfer and transport, small trucks to the biggest trucks

allowable

disposal of solid waste, landfilling with or without attempting

to recover resources.


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CLASSIFICATION OF SOLID WASTE


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DEFINITION OF SOLID WASTE


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TYPES/SOURCES OF SOLID WASTE

The sources of SW in a community are

generally related to land use and zoning. These

wastes can be group or classified in several

ways, but classifications are necessary to

address effectively the complex challenges ofsolid waste management.


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COMPOSITION OF SOLID WASTE


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COMPONENTS OF SOLID WASTE


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PHYSICAL, CHEMICAL AND BIOLOGICAL PROPERTIES OF

SOLID WASTE

Information on the properties of solid wastesis important in evaluating alternativeequipment needs, systems and managementprograms and plans, especially with respect

to the implementation of disposal andresource and recovery options.


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PHYSICAL PROPERTIES OF SOLID WASTE

Physical composition of SW including : identification of theindividual components that make SW, analysis of particle size,moisture content and density of SW.

Individual Components

Components that are typically make up most SW listed belowhave been selected because they are readily identifiable,consistent with component categories reported in the literatureand are adequate for the characterization of solid wastes formost applications.


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MOISTURE CONTENT

The moisture content of solid wastes usually is expressed in one of

two ways. In the wet weight method of measurement, the moisturein a sample is expresses as a percentage of the wet weight of thematerial ; in the dry weight method, it is expressed as a percentageof the dry weight of the material.

WET WEIGHT MOISTURE CONTENT

In equation form, the weight moisture content is expressed asfollows

M = (w-d)100

w

Where M= moisture content, %

w= initial weight of sample as delivered, kg

d=weight of sample after drying at 1050C, kg


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Table 1 Typical data on moisture content of solid waste

componentsMoisture (%) Moisture (%)

Component Range Typical

Food wastes

Paper

Cardboard

Plastics

Textiles

Rubber

Leather

Garden trimmings

Wood

Misc. Organics

GlassTin cans

Nonferrous metals

Ferrous metals

Dirt, ashes, brick

Municipal solid waste

50-80

4-10

4-8

1-4

6-15

1-4

8-12

30-80

15-40

10-60

1-42-4

2-6

2-6

6-12

15-40

70

6

5

2

10

2

10

60

20

25

23

2

3

8

20


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EXAMPLE 1

Estimate the moisture content of 100kg

solid waste sample with the following

composition:

Component Percent by mass

Food waste 15

Cardboard 10

Plastics 10

Garden trimmings 10

Wood 5

Tin cans 5

Paper 45


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Solution:

1. Set up a table to determine the dry mass of the solid

waste sample using data given in Table 1

2. Determine the moisture contentMoisture content =

Component Percent by

mass

Moisture

content (%)

Dry mass, kg

(based on 100kg)

Food waste 15 70

Paper 45 6

Cardboard 10 5

Plastics 10 2

Garden

trimmings

10 60

Wood 5 20

Tin cans 5 3


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Solution:

1. Set up a table to determine the dry mass of the solidwaste sample using data given in Table 1

2. Determine the moisture contentMoisture content =

Component Percent by

mass

Moisture

content (%)

Dry mass, kg

(based on 100kg)

Food waste 15 70 4.5

Paper 45 6 42.3

Cardboard 10 5 9.5

Plastics 10 2 9.8

Garden

trimmings

10 60 4.0

Wood 5 20 4.0

Tin cans 5 3 4.9

79.0


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DENSITY

Densities of solid wastes vary markedly with geographiclocation, season of the year and length of time in storage.

Density (kg/m3) Density (kg/m3)

Component Typical Range

Food wastesPaper

Cardboard

Plastics

Textiles

Rubber

LeatherGarden trimmings

Wood

Misc. Organics

Glass

Tin cans

120-48030-130

30-80

30-130

30-100

90-200

90-26060-225

120-320

90-360

160-480

45-160

29085

50

65

65

130

160105

240

240

195

90

Table 2 Typical densities for solid wastes componentsand mixtures


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Typical densities for solid wastes components and mixtures

Density (kg/m3) Density (kg/m3)

Component Typical Range

Nonferrous metals

Ferrous metals

Dirt, ashes, brick

Municipal solid waste

Uncompacted

Compacted

(in compactor truck)

In landfill(compacted normally)

In landfill

60-240

120-1200

320-960

90-180

180-450

350-550

600-750

160

320

480

130

300

475

600


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EXAMPLE 2

Estimate the density of a solid waste sample with the

composition given in Example 1


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Solution:1. Set up a table to determine the discarded volume of solid

waste sample using the data reported in Table 2

2. Determine the density of a waste sampleDensity =

Component Percent by mass Typical density

Kg/m3Volume*, m3

Food waste 15 290

Paper 45 85

Cardboard 10 50

Plastics 10 65

Garden

trimmings

10 105

Wood 5 240

Tin cans 5 90

*Based on a 1000kg sample of waste


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Solution:1. Set up a table to determine the discarded volume of solid

waste sample using the data reported in Table 2

2. Determine the density of a waste sampleDensity =

Component Percent by mass Typical density

Kg/m3Volume*, m3

Food waste 15 290 0.52

Paper 45 85 5.29

Cardboard 10 50 2.00

Plastics 10 65 1.54

Garden

trimmings

10 105 0.95

Wood 5 240 0.21

Tin cans 5 90 0.56

*Based on a 1000kg sample of waste 11.07


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CHEMICAL PROPERTIES OF SOLID WASTE

Information on the chemical composition of thecomponents that constitute SW is important inevaluating alternate processing and recovery

options. For example, the feasibility ofcombustion depends on the chemicalcomposition of the solid wastes. 3 mostimportant properties to be known are

Proximate analysis

Energy content

Ultimate analysis (major element)


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PROXIMATE ANALYSIS

Proximate analysis for the combustiblecomponents of SW includes the following tests:

Moisture (loss of moisture when heated to 1050C

for 1h) Volatile combustible matter (additional loss of

weight on ignition at 9500C in a covered crucible)

Fixed carbon(combustible residue left after volatile

matter is removed) Ash (weight of residue after combustion in an

open crucible)


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ENERGY CONTENT OF SOLID

WASTE COMPONENTS

Energy values may be converted to a dry basis by using

kJ/kg (dry basis)= kJ/kg x100

100-% moisture

kJ/kg (ash free dry basis)= kJ/kg x100

100-% ash -% moisture


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EXAMPLE 3

Estimate the energy content of a solid

waste sample with the composition

given in Example 1. What is the contentof dry basis and ash-free dry basis?


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SOLUTION :

1. Set up a table to determine the energy content of the SW

sample using the data reported in Table 3.6 (Based on a 100 kg

sample of waste)

Components Percent by

mass

Total energy

kJ

Food wastes

Paper

Cardboard

PlasticsGarden

trimmings

Wood

Tin cans

15

45

10

1010

5

5

69,750

753,750

163,000

326,00065,000

93,000

3,500

1,474,000


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2. Compute the unit energy content

Energy content (kJ/kg) =

3.Determine the energy content on dry basis

a. From Example 1, the moisture content of the waste is 21.0%.

4.Determine the energy content on ash free dry basis

a. Assume the ash content of the waste is equal to 5.0%.


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ULTIMATE ANALYSIS

Ultimate analysis of a waste component typically involves the

determination of the percent C, H, O, N, S and ash. Because of

the concern over the emission of the chlorinated compounds

during combustion, the determination of halogens is often

included in an ultimate analysis.

The results of the UA are use to characterize the chemical

composition of the organic matter in SW. They are also use to

define the proper mix of waste materials to achieve suitable C/N

ratios for biological processes.


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Chemical content

If energy values are not availableapproximate values may be determine

kJ/kg =337C + 1428 (H-O/8) + 9SWhere

C= carbon, %

H = hydrogen, %

O = oxygen, %

S = sulfur, %


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EXAMPLE 4Derive an approximate chemical formula for the organic portion of a

solid waste sample with the composition given. Use the

resulting chemical composition to estimate the energy contentSolution:

1. Set up a table to determine the overall composition of the wastebased on 100kg sample.Moisture content given is 20.9 kg

Component Composition

C H O N S Ash

Food waste 2.16 0.29 1.69 0.12 0.02 0.23

Paper 18.4 2.54 18.6 0.13 0.08 2.54

Cardboard 4.18 0.56 4.24 0.03 0.02 0.48

Plastics 5.88 0.71 2.23 - - 0.98

Garden trimmings 1.91 0.24 1.52 0.14 0.01 0.18

Wood 1.98 0.24 1.71 0.01 - 0.06

Total 34.51 4.58 30 0.43 0.13 4.47


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EXAMPLE 4

2. Prepare a summary table of the above data

Component Mass,kg

Carbon 34.51

Hydrogen 4.58

Oxygen 30

Nitrogen 0.43

Sulfur 0.13

Ash 4.47


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Solution:

3. Calculate percentage by mass

Component Mass,kg Percentage by mass

Carbon 34.51 36.3

Hydrogen 4.58 + 2.32= 6.9 7.3

Oxygen 30 +18.58 = 48.58 51.1Nitrogen 0.43 0.5

Sulfur 0.13 0.1

Ash 4.47 4.7

Total 95.02 100


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Moisture content given is 20.9.Convert

the moisture content (given 20.9kg) to

H and Oa. H = 2/18(20.9) kg = 2.32 kg

b. O = 16/18(20.9) kg = 18.58 kg


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Solution:

Estimate the energy content of the waste kJ/kg =337C + 1428 (H-O/8) + 9S

Where

C= carbon, %

H = hydrogen, %

O = oxygen, %

S = sulfur, %


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Solution:

Estimate the energy content of the waste kJ/kg = 337 (36.3) + 1428 (7.3-51.1/8) + 9 (0.1)

= 12, 223 + 1,303 + 9.5

= 13,546

Computations such as above are especially important

where the recovery of energy from solid waste is beingconsidered


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Biological Properties

VS, volatile solids, ignition at 550 C is often used as a measureof the biodegradability of the organic fraction.

An alternative is the lignin content can be used to determine

biodegradability:

BF = 0.83 - 0.028 LC

BF is the biodegradable fraction and LC is the lignin content.

Odors typically result from the anaerobic decomposition of the

organic fraction.

- Sulfate is reduced to sulfides and the to H2S.


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ODORS The production of odors and the generation of flies are related to the

putrescible nature of the organic materials found in MSW (eg food waste)

Odors can develop when solid waste are stored for long periods of time onsite between collections, in transfer stations and in landfill. Typically the

formation of odors results from the anaerobic decomposition of the readily

decomposable organic components found in MSW.

In the summertime and during all season in warm climate, fly breeding is an

important consideration in the on-site storage of wastes. Flies can develop

in less than 2 weeks after the eggs are laid. The life history of the common

house fly from egg to adult can be described as follows:

Egg develop 8-12 hrs

First stage of larval period 20 hrs

Second stage of larval period 24 hrs Third stage of larval period 3 days

Pupal stage 4-5 days

Total 9-11 days


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COMMON FLY BREEDING

House and stable flies breed in areas where moist organic

matter is present. Common fly breeding sites on livestockoperations include locations in and around

(1) leak and spill areas;

(2) animal stalls and pens, feed preparation, storage areas, near

water sources;

(3) hospital and maternity areas;

(4) water tanks;

(5) feed troughs;

(6) inside and outside manure handling areas

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Chapter Solid Waste