1. Solid and Hazardous waste Engineering
ENVE 521

2. INTRODUCTION Definition i) Solid wastes
Solid waste are any solid object, (not liquid) that has no value to its processor and wants to dispose of them.
ii) Solid waste management system
A Management system to utilize solid waste in the most-effective combination of management options to handle waste or wastestreams within the confines of applicable regulations.

3. GENERATION OF SOLID WASTES
Source - fixed, permanent
-Residential, commercial, industrial, open area, treatment plant, agricultural,demolition
Source - non-specific, diffuse
-This is in contrast to residential, industrial and commercial sources which are also diffuse but specific in that the generation of the wastes is a recurring event.
-Wastes from hospital, veterinary, condemned goods, unfit food, abattoir.

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2. Sources of Solid Wastes (7 Major Sources)
Typical solid waste generating facilities, activities and locations associated with various source classification

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7. GENERATION OF SOLID WASTES
Residential
Solid matter originated from household units such as, food waste, paper, paper item, plastic container, glass, bottle, dust, ceramic product, yard waste (grass, branches, wood) and unwanted household items such as chairs, bed, electric goods and etc.

8. GENERATION OF SOLID WASTES
Commercial
Solid waste originated from office, bank, retail shop, eating house, school, hospital. Most waste originated from packaging works.

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Industrial
Waste originated from product processing activities or wasted end product. Example: sludge from WWTP, chemical waste and packaging boxes.

10. GENERATION OF SOLID WASTES
Special Wastes (Open area)
a. Special wastes include street sweepings, roadside litter, litter from municipal litter containers, catch-basin debris, dead animals, an abandoned vehicles, waste oil etc.

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Treatment Plant Wastes
The solid and semisolid wastes from water, wastewater, and industrial waste treatment facilities. The specific characteristics of these materials vary, depending on the nature of the nature of the treatment process. The trend is that disposal from treatment plant will become a major factor in any solid waste management plan.

12. GENERATION OF SOLID WASTES
Agricultural Wastes
Wastes and residues from diverse agricultural activities, such as the planting and harvesting of row, field, and tree and vine crops, the production of milk, the production of animals for slaughter, and preparation of feedlots.
Characteristics - mainly organic and easily degradable. The disposal of these waste is not the responsibility of most municipal and country solid waste management agencies.

13. GENERATION OF SOLID WASTES
Demolition and construction wastes
Demolition wastes from razed buildings and other structures.
Construction wastes from construction, remodeling and repairing of individual residences, commercial buildings and other structures.
Including stones, concrete, bricks, plaster, lumber, shingles and plumbing heating and electrical parts.
Difficult to estimate and variable in composition.

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Characteristics - mainly non-combustible such as stones, loose concrete, bricks, plaster, plumbing, heating and electrical parts. Combustible such as wood.

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3. Types of Solid Wastes (Waste Characteristic)
i) Food wastes (Garbage)
Material such as meat, fats, fruit, or vegetable residue from handling, preparation, cooking and eating of foods.
Characteristic - can be easily rotten (putrescible) and will decompose rapidly which will lead to the development of offensive odours.
[Apart from those generated at residences, considerable amounts are generated at fast-food shop, cafeterias, restaurant, large institution, markets (wholesale & retail)]

16. GENERATION OF SOLID WASTES
ii. Rubbish
Wastes other than food from house holds, institutions, commercial activities, etc., which consists of combustible and noncombustible solid wastes.
Combustible rubbish includes (mainly organic)
* paper *cardboard *plastics *textiles *rubber
* Leather *wood *furniture * garden trimmings

17. GENERATION OF SOLID WASTES
Noncombustible rubbish includes (mainly inorganic)
*Glass
* tin cans
*aluminum
*ferrous and other nonferrous metals
* dirt

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iii) Ashes and residues
Materials remaining from the burning wood, coat, and other combustible wastes.
From homes, stores, institutions, industrial and municipal facilities for purposes of heating, cooking, power generation and disposing of combustible wastes.
Characteristics - Ashes and residues are normally composed of fine, powdery material cinders, clinkers, and small amounts of burned and partially burn materials.

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4. Physical Composition of Solid Wastes
i) Individual component

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ii) Particle size
Screens
- 160 mm
- 80 mm
- 40 mm
- 20 mm below is “fines”
- 10 mm
- 5 mm

21. GENERATION OF SOLID WASTES
iii) Moisture content
The moisture content of solid wastes usually is expressed as the mass of moisture per unit mass of wet or dry material.
Wet Weight
Moisture Content (%) = [ (a-b) / a ] x 100
where a = initial mass of sample as delivered
b = mass of sample after drying

22. GENERATION OF SOLID WASTES
*Drying condition is in a over at 77oC(170oF) for 24 hours. This temperature is used to dehydrate the material completely and to limit to vaporization of volatile materials.
Dry Weight
Moisture Content (%) = [(a-b) / a ] x 100
where a = initial mass of sample as delivered
b = mass of sample after drying

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For most industrial waste, the moisture content will be in the range of 10% to 35%

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Question 1:
Estimate the moisture content of a solid waste sample with the following composition:

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Solution Steps
(1) Set up a computation table
GENERATION OF SOLID WASTES
(2) Determine the dry mass of the solid wastes sampling using the data given in the Table.
(3) Determine the moisture content using Equation and the data from above table

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iv) Density
The density of solid wastes usually is expressed as the mass of material per unit volume of waste
Density = mass / volume (kg/m3)

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Because the densities of solid wastes vary markedly with geographical location, season of the year, and length of time in storage, great care should be used in selecting typical values.

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Question 2:
Estimate the “as-discarded: density of a solid waste sample with the composition given in the example.

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Solution Steps
(1) Set up a computation table
(2) Determine the as-discarded volume of the solid waste sample using the data reported in Table
(3) Compute the density of a waste sample using the data from above table

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Solutions 1 & 2: Estimating the moisture content and density of a solid-waste sample
Composition of Mass for a solid-waste sample

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Solution 1 & 2
(1) Set up a computation table to determine the dry mass and the as-discarded volume if the solid-waste sample using the data given in the above table.( Assume waste weight= 1000kg) a b

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(2) Determine the moisture content using the following equation.
Moisture Content (%) = [ (a-b) / a ] x 100
where a = initial mass of sample as delivered
b = mass of sample after drying
(3) Determine the density of a solid-waste sample using the following equation
Density = T. mass / T. volume (kg/m3)

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5. Chemical Composition of Solid Wastes
Use - To evaluate alternative processing, recycling and recovery options
Essential properties to be known are:
(1) Proximate analysis
a. Moisture (loss at 105oC for 1 hour)
b. Volatile matter (additional loss on ignition at 950oC)
c. Ash (residue after burning)
d. Fixed carbon (remainder)
(2) Fusing point of ash

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(3) Ultimate analysis (Elemental analysis), percent of C (carbon), H (hydrogen), O (oxygen), N (nitrogen), S (sulfur), and ash (chlorine, fluorine, metals) 5g sample.
(4) Heating value (energy value) - Calorific value

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Heating value
Typical data on the energy content and inert residue for solid waste are shown below.

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Energy values may be converted to a dry basis by using the following equations:
kJ/kg (dry basis) = kJ/kg (as discarded) x
100 - % moisture
The corresponding equation of an ash-free dry basis is:
kJ/kg (ash-free dry basis)= kJ/kg (as discarded) x
100 - % moisture - % Ash

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The example to illustrate the application of the data in above Table.

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Compute the unit energy content
Energy content = 1,474,000kJ/100kg = 14,740kJ/Kg
Determine the energy content on a dry basis
kJ/kg (dry basis) = 14, x 100 = 18,658kJ/Kg
( )
Determine the energy content on an ash-free dry basis assume the ash content is equal to 5%
kJ/kg (ash-free dry basis) = 19,919.0kJ/kg

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If the average heating value (CV) of industrial coal is 28,000 kJ/kg, what percentage of the heating value of coal is the heating value of the waste.
% of CV of coal is the CV of the waste
= (14,740 / 28,000) x 100 %
= 53%
This result can interpret that burning 2 ton of municipal waste can generate the same heating value of burning 1 ton of coal.

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If energy value are not available,
Modified Dulong formula
Estimation of energy value (kJ/kg) = 337C (H-O/8) + 9S
where C = carbon percent
H = hydrogen percent
O = oxygen percent
S = sulfur percent

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Solution
1) Calculate the dry weight of the waste

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2) Set up a computation table to determine the overall composition of the waste based on a 100 kg sample.
4.47

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3) Prepare a summary table of the above data.
4) Convert the moisture content (H2O)reported in step 2 to hydrogen and oxygen.
a. Hydrogen = (2/18) x 20.9 = 2.32 kg
b. Oxygen = (16/18) x 20.9 = kg
20.90
34.51
4.58
30.00
0.43
0.13
4.47

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5) Prepare a revised summary table similar to the one prepared in step 2 using the data from step 3. = =

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6) Compute molar composition of the elements

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7) Determine an approximate chemical formula with and without sulfur.
- Chemical formula with sulfur: C H O N S
- Chemical formula without sulfur: C H O N