Transcript The Environmental Effects of Organic Waste In Was+

The Environmental
Effects of Organic
Waste In Waste
Treatment Systems
Harrison Elba
SHWPCE Spring 2014
3 Systems
• Composting
• Aerobic decomposition
• Landfill Gas Energy
• Anaerobic decomposition
• Waste to Energy
• Combustion
Assumptions
•
•
•
•
•
1 metric ton MSW subject to all 3 systems
Contains 25% organic waste (560 lbs)
Composting reduces mass by 20%
Divert 100% organic matter from waste stream for USA
Average heating content of unsorted MSW is 4500 BTU/ dry lb
Composting
• 560 lbs organic waste
• Subjected to aerobic decomposition yields 448 lbs mature
compost and 1350 scf methane
• Diversion produces 103 billion lbs
• Application depth of 1 foot allows 18,000 acres of farmland to
be covered each year
Landfill Gas Energy
• Anaerobic decomposition yields 2,200 scf methane
• 2 MMBTU
• 10 days worth of gas energy for average home if captured, or
high emissions if not captured
• Diversion to compost prolongs landfill life by 25% but makes
LGE projects obsolete
Incineration
•
•
•
•
Combustion of 1 ton of unsorted MSW yields 10 MMTU
1 ton CO2 + fine particulate, heavy metals, dioxins, acid gasses
Cogen is best practice
Diversion to compost reduces combustion heat value potential
of waste stream by approx 50%
Conclusions
•
•
•
•
Lack of emissions data
One method is not superior to the other 2
Combination is necessary
Compost organic, combust the rest, landfill ash
Yucca Mountain
Controversy
Risks
•
•
•
•
Radiation emissions
Water infiltration
Seismic activity
Vulnerability to attack
Why Yucca?
• DOE estimated public dose of .24-.98 mrem/year over 1
million years is less than EPA acceptable dose of 350
mrem/year
• Would take thousands of years for water to infiltrate site
• All fault lines were out of critical zones
• Easy to defend location near military bases
Conclusions
• Public and political overreaction to slightly adverse
unanticipated discoveries disregarded the ability to engineer
solutions
• The ensuing political dance regarding “Precautionary
Principle” did not account for inherent risk in current
distributed storage methods
• Will not necessarily discover a more favorable storage site,
and the earth was not designed for this purpose