burning and burying solid waste

1. Burning and Burying SolidBurning and Burying Solid
WasteWaste

2. BURNING SOLID WASTEBURNING SOLID WASTE
 Waste-to-energy incineratorWaste-to-energy incinerator – burn waste– burn waste
to bto boil water to make steam for heating or foroil water to make steam for heating or for
production of electricityproduction of electricity

> 600 worldwide> 600 worldwide

Japan and a few European countries incinerateJapan and a few European countries incinerate
most of their MSWmost of their MSW

U.S. 9% - 115 incineratorsU.S. 9% - 115 incinerators

3. BURNING SOLID WASTEBURNING SOLID WASTE
 How a power plant worksHow a power plant works

4. Burning Solid WasteBurning Solid Waste
 Waste-to-energy incinerator with pollutionWaste-to-energy incinerator with pollution
controls that burns mixed solid wastecontrols that burns mixed solid waste

5. Fig. 22-11, p. 531
Reduces trash
volume
Can compete
with recycling
for burnable
materials such
as newspaper
Output approach
that encourages
waste production
Older or poorly
managed facilities
can release large
amounts of air
pollution
Some air pollution
Difficult to site
because of citizen
opposition
Costs more than
short-distance
hauling to
landfills
Expensive to build
Some facilities recover
and sell metals
Modern controls reduce
air pollution
Sale of energy
reduces cost
Concentrates
hazardous
substances
into ash for
burial or use
as landfill
cover
Low water
pollution
Less need
for landfills
Trade-Offs
Incineration
Advantages Disadvantages

6. Burying Solid WasteBurying Solid Waste
 Most of world’s MSW is buried (67% in U.S.)Most of world’s MSW is buried (67% in U.S.)
 Eventually expected to leakEventually expected to leak leachateleachate
(contaminated water) into soil and aquifers(contaminated water) into soil and aquifers
 Open dumpOpen dump – fields or holes in ground– fields or holes in ground
where MSW is deposited and sometimeswhere MSW is deposited and sometimes
covered with soil- historically in developedcovered with soil- historically in developed
and mostly in developing countriesand mostly in developing countries
 Sanitary landfillSanitary landfill – solid wastes are spread– solid wastes are spread
out in thin layers, compacted and coveredout in thin layers, compacted and covered
daily with a fresh layer of clay or plastic foamdaily with a fresh layer of clay or plastic foam

7. Burying Solid WasteBurying Solid Waste
 Sanitary landfillsSanitary landfills::

Reduce risk of fire, decrease odor, reduces pestsReduce risk of fire, decrease odor, reduces pests

Located in geologically suitable sitesLocated in geologically suitable sites

Bottom covered with linings – clay, plastic, sandBottom covered with linings – clay, plastic, sand
to channel and collect leachate – then treatedto channel and collect leachate – then treated
 Vented to collect gases methane (CHVented to collect gases methane (CH44) and CO) and CO22

Many older ones will have problems –Many older ones will have problems –
groundwater contamination, gases, firesgroundwater contamination, gases, fires

8. Fresh Kills Landfill, Staten IslandFresh Kills Landfill, Staten Island
 World’s largest landfillWorld’s largest landfill
 Closed in 2001 – reopened for 9/11 debrisClosed in 2001 – reopened for 9/11 debris
 Being turned into a parkBeing turned into a park

9. Fig. 22-12, p. 532
Sand
When landfill is full,
layers of soil and clay
seal in trash
Methane storage
and compressor
building
Leachate
storage
tank
Leachate
monitoring
well
Groundwater
monitoring
well
Electricity
generator
building Leachate
treatment system
Methane gas
recovery well
Compacted
solid waste
Leachate
pipes
Leachate pumped
up to storage tank
for safe disposal
GroundwaterClay and plastic lining
to prevent leaks; pipes
collect leachate from
bottom of landfill
Topsoil
Sand
Clay
Subsoil
Probes to
detect
methane
leaks
Garbage
Garbage
Synthetic
liner
Sand
Clay
Pipes collect explosive
methane as used as fuel
to generate electricity

10. How Does a Modern
Landfill Work?

11. Fig. 22-13, p. 533
No open burning
Trade-Offs
Sanitary Landfills
Advantages Disadvantages
Eventually leaks and can
contaminate groundwater
Discourages recycling,
reuse, and waste reduction
Slow decomposition
of wastes
Groundwater contamination
Releases greenhouse
gases (methane and CO2)
unless they are collected
Air pollution from toxic
gases and volatile organic
compounds
Dust
Noise and traffic
No shortage of landfill
space in many areas
Filled land can be used
for other purposes
Can handle large amounts
of waste
Can be built quickly
Low operating costs
Low groundwater
pollution if sited
properly
Little odor

12. Case Study: What Should We Do withCase Study: What Should We Do with
Used Tires?Used Tires?
 Dilemma – what toDilemma – what to
do with hundredsdo with hundreds
of millions ofof millions of
discarded tiresdiscarded tires
 Health hazard –Health hazard –
mosquitoesmosquitoes
 FiresFires
 Can be recycled,Can be recycled,
made into reefsmade into reefs