10.0 Waste Processing.ppt 9881KB Mar 29 2010 05:00:29 AM

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10.1 Overview and objectives of waste processing

techniques

10.2 Waste sorting

10.3 Composting

10.4 Reuse and recycling

10.5 Mechanical and Biological treatment

10.6 Incineration

10.7 Land filling

Outline Outline

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10.1 Overview and objectives of

waste processing techniques

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Objectives

• to reduce the hazardous nature of the waste

• to separate the waste into its individual components, some or all of which can then be put to further use/treatment

• to reduce the amount of waste which has to be finally sent for disposal

• to transform the waste into a useful material

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Waste

reception

reception _mediate_mediateInter-Inter- TreatmentTreatment

storage

Storage

Storage DisposalDisposal

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Waste processing techniques

• Biological treatments and some mechanical-biological treatments

• Physico-chemical treatments

• Treatments applied to waste in order to enable the recycling/regeneration of materials

• Treatments applied to turn a waste into a material that can be used as a fuel in different industrial sectors

• End-of-pipe techniques used in waste treatment installations for the abatement of emissions

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10.2 Waste sorting

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/44 • Manually at the household and collected through _{Manually at the household and collected through}

kerbside collection schemes kerbside collection schemes

• Automatically separated in materials recovery facilities _{Automatically separated in materials recovery facilities} • Mechanical - Biological treatment systems_{Mechanical - Biological treatment systems}

Process by which waste is separated into

different elements

10.2 Waste sorting

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Biodegradable waste components

• Green waste _{Green waste} • Kitchen waste _{Kitchen waste} • Paper_Paper

Other recyclable components

• Plastics_Plastics • Glass _Glass

• Metals (ferrous and non-ferrous) _{Metals (ferrous and non-ferrous)} • Co-mingled recyclables_{Co-mingled recyclables}

10.2 Waste sorting

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Kerbside collection of recyclable resources

Purer waste streams

Higher market value

10.2 Waste sorting

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Completely environmentally friendly

Global warming

through exhaust

emissions

Increased number of

waste collection

vehicles on the

road

Kerbside collection of recyclable resources

?

BUT BUT

10.2 Waste sorting

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10.3 Waste composting

10.3 Composting

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Atoms and molecules Atoms and molecules

Living systems consist of atoms and Living systems consist of atoms and

molecules (at the Angstrőm level): molecules (at the Angstrőm level): • Carbon (C), _{Carbon (C),}

• Hydrogen (H), _{Hydrogen (H),} • Oxygen (O), _{Oxygen (O),} • Nitrogen (N), _{Nitrogen (N),}

• Phosphorus (P), _{Phosphorus (P),} • Sulphur (S), ….._{Sulphur (S), …..}

Groups of atoms make up living and Groups of atoms make up living and

non-living materials non-living materials

10.3 Composting

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/44 Example living materials:

Example living materials:

human being, animals, plants, trees human being, animals, plants, trees

Example non-living materials: Example non-living materials:

bricks, metal, stone, oxygen, water bricks, metal, stone, oxygen, water

Photosynthetic systems obtain their energy from the sun Photosynthetic systems obtain their energy from the sun

CO

CO₂₂ + nutrients + sunlight energy + nutrients + sunlight energy  organic mater organic mater Non-photosynthetic systems degrade energy-rich Non-photosynthetic systems degrade energy-rich

molecules for their growth molecules for their growth

10.3 Composting

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Organic matter such as sugar: C

Organic matter such as sugar: C₆₆HH₁₂₁₂OO₆₆

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Aerobic decomposition of biodegradable

organic matter, producing compost

Performed primarily by facultative and obligate aerobic bacteria, yeasts and fungi, helped in the cooler initial and ending phases by a number of larger organisms, and other families representing ants, nematodes and oligochaete worms

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Compost pile

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10.3 Composting

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Organisms decomposing organic matter

10.3 Composting

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/44 • A _Abiodegradablebiodegradable material is capable of being broken material is capable of being broken

down completely under the action of microorganisms down completely under the action of microorganisms into carbon dioxide, water and biomass

into carbon dioxide, water and biomass

• A _Acompostablecompostable material biodegrades substantially material biodegrades substantially under composting conditions, into carbon dioxide, under composting conditions, into carbon dioxide, methane, water and compost biomass

methane, water and compost biomass

• A _Acompost-compatiblecompost-compatible material does not have to be material does not have to be compostable or even biodegradable, is generally inert compostable or even biodegradable, is generally inert and is present in compost at relatively low levels

and is present in compost at relatively low levels

10.3 Composting

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C : N ratio

Carbon

Carbon e.g.e.g. in the form of cellulose which the bacteria need in the form of cellulose which the bacteria need for their energy (dry, straw-type material, such as

for their energy (dry, straw-type material, such as cereal straws, leaves, sawdust, wood chips, paper, cereal straws, leaves, sawdust, wood chips, paper, cardboard)

cardboard)

Nitrogen in the form of protein, which provides nutrients for Nitrogen in the form of protein, which provides nutrients for

the energy exchanges (green plant material such as the energy exchanges (green plant material such as

crop residues, hay, grass clippings, weeds, manure of crop residues, hay, grass clippings, weeds, manure of

poultry, herbivorous animals such as horses, cows and poultry, herbivorous animals such as horses, cows and

llamas; fruit and vegetable trimmings) llamas; fruit and vegetable trimmings)

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Active

• exothermic action of the bacteria as they decompose _{exothermic action of the bacteria as they decompose} the organic matter

the organic matter

• close to ideal conditions _{close to ideal conditions}

Passive

• level of physical intervention is kept to a minimum_{level of physical intervention is kept to a minimum} • more common type of composting in most domestic _{more common type of composting in most domestic}

garden compost bins garden compost bins

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Home composting

range of techniques, from extremely passive (throw range of techniques, from extremely passive (throw everything in a pile and leave it for a year or two) to everything in a pile and leave it for a year or two) to

extremely active (monitor the temperature, turn the pile extremely active (monitor the temperature, turn the pile

regularly, adjust the ingredients over time). regularly, adjust the ingredients over time).

Industrial composting

waste management alternative to landfills, along with other waste management alternative to landfills, along with other advanced waste processing systems

advanced waste processing systems

combined with mechanical sorting of mixed waste streams combined with mechanical sorting of mixed waste streams is called mechanical biological treatment

is called mechanical biological treatment

10.3 Composting

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Materials Recovery Facility (MRF)

Specialized plant that receives, separates and prepares Specialized plant that receives, separates and prepares

recyclable materials for marketing to end-user recyclable materials for marketing to end-user manufacturers.

manufacturers.

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Clean

:

accepts recyclable materials that have been collected in comingled wastes from kerbside collection

separated at source from municipal solid waste generated by either residential or commercial sources

Dirty:

accepts a mixed solid waste stream and then proceeds to separate out designated recyclable materials

through a combination of manual and mechanical sorting

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Facts and figures Facts and figures

• Landfills are used for less than 10% of all waste. Dutch _{Landfills are used for less than 10% of all waste. Dutch} household waste recycling averages to 60% (2006).

household waste recycling averages to 60% (2006). • Compost (2003): _{Compost (2003):}The separately gathered organic The separately gathered organic

fraction is 50% of household waste, or 1500 fraction is 50% of household waste, or 1500

kilotonnes. This is processed to 600 kilotonnes of kilotonnes. This is processed to 600 kilotonnes of compost

compost

• Paper (2005): _{Paper (2005):}In the Netherlands the recycled amount In the Netherlands the recycled amount in 2005 was up to 2.5 million tonnes, which is 75% of in 2005 was up to 2.5 million tonnes, which is 75% of annual consumption.

annual consumption.

Recycling in The Netherlands

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10.5

Mechanical and Biological

Treatment

10.5 Mechanical and Biological Treatment

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uses living micro-organisms to decompose organic wastes uses living micro-organisms to decompose organic wastes

into water, CO

into water, CO22 and simple inorganics or into simpler and simple inorganics or into simpler

organics such as aldehydes and acids organics such as aldehydes and acids

Biological treatment

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Several biological treatments

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Activated sludge:

Decomposes organic wastes in water Decomposes organic wastes in water

by exposing waste to biological by exposing waste to biological

growth. Water is recycled and growth. Water is recycled and aerated to facilitate biological aerated to facilitate biological

action and a sludge is generated. action and a sludge is generated.

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Aerated lagoons:

Large lagoons containing high concentrations of Large lagoons containing high concentrations of

micro-organisms. The lagoon is aerated to encourage bacterial organisms. The lagoon is aerated to encourage bacterial

growth and decomposition of waste. growth and decomposition of waste.

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Composting:

‘

‘Engineered’ mounds of waste are built to encourage the Engineered’ mounds of waste are built to encourage the

biological breakdown of organic solids, producing a humic biological breakdown of organic solids, producing a humic

substance valuable as soil conditioner substance valuable as soil conditioner

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Aerobic digestion:

Reduction of the organic content of waste. Applied to solid Reduction of the organic content of waste. Applied to solid

waste, non-continuous waste waters, bioremediation waste, non-continuous waste waters, bioremediation

and to sludge and soil contaminated with oil and to sludge and soil contaminated with oil

Anaerobic digestion:

Decomposes organic matter in closed vessels in the Decomposes organic matter in closed vessels in the absence of air. Uses two forms of bacteria: absence of air. Uses two forms of bacteria:

acid-forming and methane- acid-forming. Applied to solid-liquid forming and methane- forming. Applied to solid-liquid

wastes, highly contaminated waste waters (e.g. wastes, highly contaminated waste waters (e.g.

chlorinated compounds), bioremediation and in the chlorinated compounds), bioremediation and in the

production of biogas to be used as a fuel. production of biogas to be used as a fuel.

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Form of waste processing facility that combines a sorting Form of waste processing facility that combines a sorting

facility with a form of biological treatment such as facility with a form of biological treatment such as composting or anaerobic digestion

composting or anaerobic digestion

Mechanical Biological Treatment

Typical mechanical elements: factory style conveyors, Typical mechanical elements: factory style conveyors,

industrial magnets, eddy current separators, trommels, industrial magnets, eddy current separators, trommels,

shredders and other tailor made systems shredders and other tailor made systems

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10.6

Incineration

10.6 Incineration

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Waste treatment technology that involves the combustion Waste treatment technology that involves the combustion

of organic materials and/or substances, "thermal of organic materials and/or substances, "thermal

treatment". treatment".

Converts the waste into ash, flue gases, particulates, and Converts the waste into ash, flue gases, particulates, and

heat, which can in turn be used to generate electricity. heat, which can in turn be used to generate electricity.

Flue gases are cleaned for pollutants (particulate matter, Flue gases are cleaned for pollutants (particulate matter,

heavy metals, dioxins, furans, sulphur dioxide, and heavy metals, dioxins, furans, sulphur dioxide, and

hydrochloric acid

hydrochloric acid) ) before they are dispersed in the before they are dispersed in the atmosphere

atmosphere

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•

moving grate

•

fixed grate

•

rotary-kiln

•

fluidised bed

Types of incinerator plant design

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• Dioxin and furans_{Dioxin and furans} • Carbon dioxide_{Carbon dioxide}

• Other emissions, including sulphur dioxide, _{Other emissions, including sulphur dioxide,}

hydrochloric acid, heavy metals and fine particles hydrochloric acid, heavy metals and fine particles

Gaseous emissions

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/44 • Electrostatic precipitators (ESP) and/or baghouse _{Electrostatic precipitators (ESP) and/or baghouse}

filters filters

• Acid gas / basic scrubbers_{Acid gas / basic scrubbers} • Dry desulfurisation_{Dry desulfurisation}

• Catalytic reduction (SCR) or selective non-catalytic _{Catalytic reduction (SCR) or selective non-catalytic} reduction (SNCR)

reduction (SNCR)

• Adsorbtion on active carbon powder_{Adsorbtion on active carbon powder}

Flue gas cleaning

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• Fly ash and bottom ash_{Fly ash and bottom ash}

• Fly ash constitutes more of a potential health hazard_{Fly ash constitutes more of a potential health hazard} • High concentrations of heavy metals such as lead, _{High concentrations of heavy metals such as lead,}

cadmium, copper and zinc as well as small amounts of cadmium, copper and zinc as well as small amounts of dioxins and furans

dioxins and furans

Solid outputs

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Flue gas cleaning

NEUTREC® flue gas cleaning process (from www.neutrec.com)

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10.7 Landfilling

The presentation on landfilling is

provided in chapters 18, 19 and 20