Waste to Energy Initiatives

• National importance

• Shall be very popular soon

MSW

Mass Burning

Steam / Power

landfill Gas recovery Burn in Boiler

RDF Burning

Anaerobic digestion

Thermochemical Decomposition

Incineration of Municipal Solid Waste

(MSW)

Waste /CoalPreparation

Waste /CoalFeeding FURNACE

Bottom Ash Heat Recovery

Particle Removal

Acidic Gas Removal

STACK

Waste/Coal Aux Fuel

ID Fan

FD Fan

Heat

Flue Gas

For treatment & disposal

Gas out

TYPES FURNACES

• Stocker / Grates Type• Rotary Kiln Type• Fixed Hearth• Multiple Hearth• Cyclonic• Fluidized Bed

• MSW Mass Burning• Any type of waste• Biomedical wastes• Sewage Sludge• High heat content• Any kind of waste

Fluidized BedA bed of fine solids(usually sand)suspended in air

The gas from thebottom of thecolumn via a gasdistributor causesthe particles tofluidize

Ways of Heat Recovery

• Use a boiler to produce steam / hot water• Use a heat exchanger to pre-heat the

ambient air which can be used for combustion

• Use a heat exchanger for drying solid wastes/ concentrating liquid waste

• Use water-wall to generate steam / hot water

Heat Exchangers• To exchange heat from one fluid to another• Heat flow higher temperature side to lower

temperature• Usually no mixing up of fluids (sometimes,

they get mixed up)• Enough heat transfer area to be provided for

the heat to transfer• There are different designs / types available

Counter Current

EMISSIONS FROM INCINERATION,The emission from incineration are as follows:

1. PARTICULATE MATTERS

2. OXIDES OF NITROGEN

3. OXIDES OF SULPHUR

4. Heavy Metals

5. HCl, HF

6. CHLORINATED HYDROCARBONS (Dioxins & Furans)

7. PAH (Poly Aromatic Hydrocarbons)

8. CO

9. CO2

14

Equipment Pollutant Removed % Removal Pressure DropInches of Water Column

Settling Chamber Large particles 0 to 30 % 0.5 to 1

Multiple Cyclones Particles 30 to 80 % 3 to 4 (single cyclone: about 1)

Venturi Scrubber Particles & acidic gases like HCl, SO2

80 to 96 % 10 to 50

Packed scrubber Aerosols & acidic gases

80 to 96 % 6 to 8

ESP Fine particles 90 to 97 % 0.5 to 1

Fabric Filter bag House

Fine particles 97 to 99.9 % 1 to 8

15

Air Pollution Control

• Normally air pollution control involves more than one unit depending upon the flue gas and the requirements of the law

Removal ofcoarse particles

Removal ofFine Particles

Removal ofAcidic Gases

16

17

18

Basic Principle of Electrostatic Precipitator (ESP)19

Bag Filter House

20

21

Venturi Scrubber

22

Packed Scrubber

23

TIMARPR PLANT - MASS BURNING OF MSW - 1987

• Danish Design (Mukund-Volund)• Rs. 25 Crores• To generate 3.56 MW power from 300tones

MSW /day

• It was a failure

TIMARPUR INCINERATION FACILITY

Reasons for Failure

Wrong assumption of the heat contentHeat content assumed: 1462 Kcal/kgActual heat content: 700-900 kcal/kg

Wrong assumption of the inert contentInert content assumed: 10% by wtActual inert content: 30-50%

MSW Characteristic Vs time

• Heat content increases (avg. now 1200-1300 kCal/kg)– More paper / cardboard– More plastics– More cloths– More rubber / leather

Moisture & Inert content decreases: Less glass / metals / C&D waste

New Incineration Initiatives for MSW

• The Okhla MSW Mass Firing Incineration facility

• The Ghazipur MSW RDF-Incineration facility

Okhla MSW Mass Firing Incineration facility

• Burning raw MSW• Private –Public Partnership initiation• Jindal Urban Infrastructure Ltd

• Average calorific value 1200kcal / kg

• 1350 tons of raw MSW 14 MW

Ghazipur RDF-Incineration Facility

• 1300 tones of raw MSW / day 12 MW

• Based on DST-TIFAC technology

• First RDF (Refuse Derived Fuel) generated

• Then burning of RDF to generate Power

RDF Initiatives

• DST RDF Plant in Deonar, Bombay in 1990’s

• SELCO RDF Plant near Hyderabad, Andhra Pradesh in 2000’s – not in operation now ???

• Bangalore plant

REFUSE DERIVED FUEL

• Dry the MSW• The burnable fraction of the waste

is separated, shredded• then made pellets (using die) or

briquettes by pressing. • The pellets are made with or

without a binding agent

• Heat content of RDF is more or less uniform.– For Fluff – 3500kCal /kg– for pellets – 4000 kCal/kg

• RDF can be burnt to produce power or can be used along with conventional fuels

• In India, there are a few RDF plants at present

Co-Incineration

Co-incineration

• Co-incineration of MSW with ????• Co-incineration with Biomedical waste• Co-incineration with agro-wastes• Co-incineration with Hazardous wastes• Co-incineration in cement kilns

Co-Processing

Co-processing in cement industry refers to thesubstitution of primary fuel and raw material bywaste, recovering energy and material from waste.

Waste materials used for co-processing are referredto as alternative fuels and raw materials (AFR).

Cement Kiln Suitability

High temperatures (1400 O C) and residence time of 4 – 5seconds in an oxygen–rich atmosphere ensure the destructionof organic compounds.

Any acid gases formed during combustion are neutralized bythe alkaline raw material and are incorporated into the cementclinker.

Interaction of the flue gases and the raw material present inthe kiln ensures that the non–combustible part of the residueis held back in the process and is incorporated into the clinkerin a practically irreversible manner.

No waste is generated that requires subsequent processing.

Benefits of Co-processing

Reduction in Green House gases emission& related benefit of carbon trading

Conversion of waste into energy / as araw mix component

Conservation of fossil fuel resource

Reduction in energy / cement productioncosts

Final Disposal

• Land-dumps

• Engineered Landfills (Dry Tomb)

• Bioreactor landfills

DRY TOMB CONCEPT OF LANDFILLS

• As per the MSW (Management and Handling) Rules of 2000– No biodegradable waste ban be land-filled– Biodegradable waste should be processed for

some recovery• Composting - compost• Vermi-composting - vermi-compost• Incineration - steam / hot water / power• Biomethanation - fuel gas

– Wastes good for nothing goes to a landfill

‘Dry tomb’ engineered landfills for wastes

Landfill Construction

Final cover

Daily cover

Intermediate cover

Liner For MSW Landfill (India)

Leachate is then sent to Treatment and/or Storage Facility

Landfill

PumpStation

Gravity Drainage

LeachateStorage

Treatment

Landfill Gas is Typically Extracted to a Blower-Flare Station

Landfill

Note:Must DrainCondensate

BlowerFlare

Station

Gas Wells

MSW Landfill (India)

Economics / Cost involved

• Cost of geo-membrane: 50 cents to 1$ per square feet

• Cost of geo-textiles: 50 cents per square feet• Cost of geo-nets: 1$ per square feet• Tipping fee in US: 20$ to 50$ per tonne of

MSW• Landfilling cost in India: Rs. 200 to 500per

tonne of MSW, Rs. 2000 per tonne of Hazardous Wastes

Are you happy with Dry Tomb Landfills ???

• MSW is to be processed first for recovery• Composting or vermi-composting

• Long time for stabilization of waste• Landfill area is blocked for about a century• Leachate is to be treated and managed

• Any alternative ?? Yes…………. Go for another concept

BIOREACTOR LANDFILLS

• Landfill is considered to be a big bioreactor• No processing of biodegradables• Leachate is collected; but circulated back to

the landfill• Waste stabilization is much faster

• Aerobic – 5 to 8 years• Anaerobic – 8 to 12 years

• Landfill area is available for re-use quickly• Landfill becomes ‘sustainable’

Against the rules ?

• YES. Bioreactor landfills are not allowed in India now

• But there are on-going attempts to make bioreactor landfills in India

• Research is on in this area:• University of Florida• Anna University• IIT Delhi

Waste+ Water

+ Microorganisms

ExhaustGas

Vertical Injection Cluster Wells

Use multiple smalldiameter wells.

Subsurface Application of LeachateVertical Systems

Essential Needs for a Bioreactor

• Composite liner• Appropriate density of MSW• Appropriate daily cover• Leachate recirculation system• Active gas collection system• Appropriate final cover system• Competent landfill operator

Benefit: Leachate Management

• Important factors:

– Storm water management

– Leachate storage

Benefit: More Feasible Gas-to-Energy

• Increased gas production during a shorter time frame may make the economics of landfill gas to energy more attractive

0 10 20 30 40Time (Years)

Gas

Vol

ume Bioreactor Landfill

Traditional Landfill

Time (Years)

Concern: Uncontrolled Liquids Addition

• If leachate is added at too great of a rate, leachate breakouts and seeps can occur.

• Even under normal operating conditions, seeps can occur because of nature of waste and cover soil in a landfill

Concern: Uncontrolled Liquids Addition

• Problems with seeps:– Off-site leachate

migration

– Odors

– Vectors

– Path for gas emission

Landfill Seeps

High PermeabilityCover Soil

Leachate Seep(Outbreak)

Interception of leachate by highpermeability cover layers and subsequent transmission of leachateto the side slopeof the landfill can resultin seeps

Lesson 9, Slide 63

Landfill Seeps

Low PermeabilityCover Soil

Leachate Seep(Outbreak)

Interception of leachate by lowpermeability cover layers and subsequenttransmission of leachate to the side slopeof the landfill can result in seeps

Concern: Slope Stability

• Excessive pore water pressures in a landfill can lead to instability problems.

• Strength of waste may become reduced following decomposition.

Concern: Increased Gas Emissions• If uncontrolled, increased gas

production from bioreactor operation

• Bioreactor landfills may require different types of gas collection systems compared to traditional landfills (wells can become flooded).

• When methane is mixed with the right amount of oxygen, an ignited flame can be sustained.

• Most landfill gas as it exists in the landfill, a gas well or an extraction pipe (≈ 50% CH4, 50% CO2), does not contain enough oxygen to support a flame. It is not explosive.

• Only when the gas is mixed with the appropriate amount of air can a flame occur (5 to 15 % by Volume)

Flammability of Landfill Gases

• Initial capital costs and operation costs may be greater for bioreactor landfills compared to those of traditional landfills

• At most operations this can be offset by the gains as described previously

Concern Costs

Bioreactor Challenges• Long-term sustainability• Liquids management• Airspace recovery• Aerobic vs. anaerobic• Heterogeneity of waste• Geotechnical Stability

Public Acceptability

• Very difficult• Mostly there is much truth in the public

allegations• What is the solution ???

To sum up...................

• Technological innovations and infrastructure development in the area of solid waste management have been remarkable in the recent past

• These are mostly aimed at coping up with the rapid urbanisation and population growth

• Biological treatment techniques like composting has been getting the priority

• Innovations in composting have been mostly to reduce the time required.

• Still has not achieved the required speed

• Waste to energy initiatives are always welcome in India

• Thermal techniques will come only after biological techniques

• There are scenarios where thermal techniques are a must or preferred

• Go for them only if sufficient funds are available

• Incineration is the most popular of the thermal techniques at present

• As a technology, there is nothing wrong with incineration

• In fact incineration is very helpful to dispose of different wastes in a rapid way

• Also, this technology becomes useful in the situations where other techniques fail

• This is relatively fool proof and needs less space

• On the other hand, it is a costly technique

• Power generation is not the primary objective of incineration

• Safe waste destruction is the primary objective

• Choose the technology based on the type of waste and the destruction requirements

• Never burn chlorinated plastics (like PVC)

• Ensure enough funds for operating the facilities

• Make it economically and environmentally sustainable

• Choose the appropriate technology based on:-

• the type and characteristics of waste• destruction requirements• suitability to the locality• Long term viability

• More waste to energy plants are expected to come up in India

Thanks to

Dr. Dinesh KumarMunicipal Corporation of Delhi

Prof. Manoj DattaIndian Institute of Technology, Delhi

Prof. Timothy G. TownsendUniversity of Florida

Dr. Kurian JosephAnna University, Madras