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Types of Solid Wastes

3 General Categories

Municipal Wastes

Food wastes the animal, fruit, or vegetable residues resulting from thehandling, preparation, cooking and eating of foods

Rubbish combustible and noncombustible solid wastes, excludingfood wastes or other putrescible materials

Ashes and residues materials remaining from the burning of wood,coal, coke and other combustible wastes

Demolition and construction wastes wastes from razed buildings and

other structuresSpecial wastes wastes such as street sweepings, roadside litter,catch-basin debris, dead animals, and abandoned vehicles

Treatment-plant wastes the solid and semisolid wastes from water,Wastewater, and industrial-waste treatment facilities

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Industrial Wastes

Hazardous Wastes

- wastes arising form industrial activities and typically include rubbish, ashes,demolition and construction wastes, special wastes, and hazardous wastes

- wastes that poses a substantial danger to human, plant, or animal life

- exhibits any of the following characteristics: ignitability; corrosively; reactivity

or toxicity

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Sources of Solid Wastes

Municipal Wastes

Treatment-plant wastes,principally composed of residualsludges

Water, wastewater, and industrial treatmentprocesses, etc.

Treatment plantSites

Special wastes, rubbishStreets, alleys, park, vacant lots, playgrounds,beaches, highways, recreational areas, etc.

Open Areas

Food wastes, rubbish, ashes,demolition and constructionwastes, special wastes,occasionally hazardous wastes

Stores, restaurants, markets, office buildings,hotels, motels, prints shops, auto repair shops,medical facilities and institutions, etc.

Commercial

Food wastes, rubbish, ashes,special wastes

Single family and multifamily dwellings, low-,medium-, and high-rise apartments, etc.

Residential

Types of solids wastesTypical facilities, activities, or Locations where wastes are generated

Source

Table 1. General Sources of Municipal Solid Wastes

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Properties of Solid Wastes

Physical Composition

Individual Components

Food wastes, paper, cardboard, plastics, textiles, rubber, leather, wood,garden trimmings, glass, tin cans, nonferrous metals, ferrous metals, dirt,ashes brick, etc.

Particle Size

Moisture Content

Important in the recovery of the materials

Express as the mass of moisture per unit mass of wet or dry material

Density

Vary with geographic location, season of the year, and length of time in storage

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i n e e r i n g Chemical Composition

1. Proximate Analysis(a) Moisture (loss at 105 0C for 1 hr)(b) Volatile Matter (additional loss on ignition at 950 0C)(c) Ash (residue after burning)

(d) Fixed Carbon (remainder)6. Fusing Point of Ash7. Ultimate Analysis8. Heating Value (Energy Value)

4 Important Properties for Solid waste to be used as Fuel

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Solid-Waste Management: An Overview

Materials Flow in Society

Manufacturing

Raw Material

Final Disposal

Consumer

SecondaryManufacturing

Processingand

Recovery

Residual debris

Residual waste material

Raw materials, products and recovered materialsRaw materials, products and recovered materials

Waste materials

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Reduction in Raw Materials Usage

Reduction in Solid-Waste Quantities

Reuse of Solid-Waste Materials

Materials Recovery

Energy Recovery

Day-To-Day Solid-Waste Management

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SEPARATION

The wastes that are desirably separated at source are:

Food wastes Paper and cardboard Plastic Metals ferrous Metals non-ferrous Glass

All other household waste that can be delivered to drop-off centers include:

Bulky waste Yard waste Hazardous household waste

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Requirements for Source Separation

Infrastructure required:

Community drop-off centers Public drop-off centers ( civic amenity centers) Environmental advertising programmes

Manual and Mechanical Sorting

Manual sorting can only be recommended for clean, dry and more or less pre-sorted waste

Mechanical sorting more commonly used for all fractions can be sorted

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Storage and Transport of Solid Waste

The type of storage used depends on the collection

facility, which may be: Doorstep Collection Regular kerb collection Civic amenity drop-off Haulier for skip collection of bulky items Community recycle bins Vacuum trucks

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Biological Solid Waste Treatment

Three options for biological solid waste treatment:

Aerobic or composting Anaerobic or biogas Combined anaerobic and aerobic

Composting 43222 SO NH O H COcellsnewOmatter organic

bacteriaaerobic ++++ +

Process Requirements

Temperature Moisture Content Oxygen C/N ratio pH Biochemical composition and texture

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Temperature

Psychrophilic 15 to 20 0C Mesophilic 25 to 35 0C

Thermophilic 50 to 600

CMoisture Content

Optimum moisture content 50 to 60%

Oxygen

Optimum oxygen levels 15 to 20%

C/N ratio

Optimum ratio 30

pH

Optimum pH 6 to 8

Biochemical Composition and texture

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Environmental Parameters

Heavy metals Odor Sterilization Inert Contaminants

Anaerobic DigestionS H NH CH COcellsnewO H matter organic bacteriaanaerobic 23422 ++++ +

Processes Involved

Hydrolysis Acidogenis Methanogenesis

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Process Requirements

Be oxygen free Not to contain inhibiting salts Have a 6.5 < pH < 7.5 Be of adequate alkalinity, 1500 to 7500 mg/L

Have sufficient nutrients Be temperature steady at either mesophilic or thermophilic conditions Have constant solids loading rate

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i n e e r i n g Two-Stage Anaerobic and Aerobic Methods

No external water is needed for producing a slurry feedstock

to the anaerobic digester. No effluent water is produced. There are high rates of biogas production. A stabilized humus product is produced. A refuse derived fuel is produced.

High solidsanaerobic

digester

Aerobiccomposter

Dryer

Digestedsludge

OrganicSolid Waste

Mixer Thermal EnergyBiogas

Air

Humus

SoilAmendment

RefuseDerivedFuel

Plug flowreactor

Aerobicreactor

Blendtank

Flow diagram for combined treatment or organic solid waste and municipal sludge.

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Thermal Treatment Combustion/Incineration

Gasification degradation takes place with a deficit of oxygen

Pyrolysis if the gasification is dry distillation

Combustion thermal degradation with excess oxygen

Incineration chemical oxidation at high temperatures

1870s in United Kingdom - first waste incineration plant was built

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Incinerator

Design Principles for Waste Incinerators

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The combustion Process in Waste Incinerators

Drying Gas pyrolysis and gas combustion Combustion or carbon residue

Design Principles for Waste Incinerators

Unloading and storage of waste

CraneHopper and feeding systemGrates

FurnaceAir Supply

Boiler systemSlag and ash removal

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Air Emission and Flue Gas Cleaning

REACTOR

Bag Filter

Flue Gas

Water

ChimneyStack

Residue

Container Hydrated lime

Silo

Layout for a dry flue gas cleaning process.

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Solid Waste Landfill

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Hazardous Wastes

Ignitable - the substance causes or enhances fire

Reactive - the substance reacts with others and may explode

Corrosive - the substance destroys tissues or metals

Toxic - the substance is a danger to health, water, food and air

Task of an Environmental Engineer....

- identify the hazardous waste streams- for each stream, quantify the waste

- for each stream, characterizing the waste according to whether its form is physical, chemical or biological

- recommending waste minimization measures- identifying hazardous waste treatment options- specifying safe disposal routes for waste residues of treated waste

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Hazardous Wastes

A solid waste that may cause or significantly contribute to an increase inmortality or an increase in serious irreversible or incapacitating reversible illness;

or pose a substantial present or potential hazard to human health or the environment when it is improperly treated, stored, transported, dispose of or otherwise manage;

and the characteristic can be measured by a standardized test or reasonabledetected

by generators of solid waste through their knowledge of their waste. (USEPA)

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Hazard Category Directive 91/689H1 ExplosiveH2 Oxidizer H3A Highly flammableH3B FlammableH4 IrritantH5 Harmful

H6 ToxicH7 CarcinogenicH8 CorrosiveH9 InfectiousH10 Teratogenic

H11 MutagenicH12 Water contact liberates toxic gasH13 Source of hazardous substanceH14 Ecotoxic

Table 2. EU hazard categories of hazardous waste

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Hazardous waste generated around your house...Hazardous waste generated around your house...

antifreeze herbicides insect repellent batteries insecticides brake fluid kerosenechemical strippers lawn chemicalschlorine bleach lighter fluidscontact cement lyedrain cleaners moth ballsfire extinguisher nail polish remover flea collars and sprays old propane tank

prescription drugs spot remover toilet cleaners used motor oil

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Medical Hazardous WasteMedical Hazardous Waste

- Obsolete medicines past the expiry date- Cytostatica with a special demand for careful handling

- Infectious material- Pathological waste- Sharp and pointed items- Waste from dental clinics

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Hazard Symbols for Chemicals

Explosive (E) Oxidizing agent (O) Highly Flammable (F) Extremely Flammable (F+)

Toxic (T) Very Toxic (T+) Harmful (Xn) Irritant (Xi)

Corrosive (C) Dangerous for theenvironment (N)

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Warning Labels for Transport of Dangerous Goods

Explosives Gases

Flammable Solids

Flammable Liquids

Oxidizing substance Toxic substance

Radioactive Material CorrosiveMiscellaneous

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Cryogenics This Way Up

Magnetic Material Cargo Aircraft Only

Warning Labels for Transport of Dangerous Goods

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