Los retos en la gestión de residuos urbanos en una economía globalizada
Els reptes en la gestió de residus urbans en una economia globalitzada
Challenges in waste management in a globalized economy
ORGANIZADO POR: CON LA COLABORACIÓN DE:
VOC emissions from organics management: Measurement, speciation and mitigation
Robert HorowitzCalifornia Dept. of Resources, Recycling & Recovery
(CalRecycle)[email protected]
This Presentation1. Composting in California today2. Do compost emissions lead to harmful air
pollution?3. Composting emissions research4. Odor issues and research5. Climate change research
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California LawCities and counties must divert >50% of their
solid waste away from landfills or CalRecycle can issue fines
Composting IS recyclingNEW: CA recycling goal: 75% by 2020NEW: Businesses with >3 cubic meters of
garbage per week must recycleNEW: Apartment buildings with 5 or more units
must offer recycling to residents
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Open-windrow composting
20 hectare green waste facility near Modesto, CA
Composting in CaliforniaMost facilities compost source separated green waste in
open windrows115 facilities / 4 million tonnes processedMost compost sold to agriculture, but farmers do not
want to pay too muchNew air- and water-quality regulations will require facility
upgrades to capture volatile organic compounds and ammonia
Economics do not support highly engineered, aerated composting facilities
Tarped, aerated systems
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Micro-pore covers80%-plus VOC & NH3 captureScalable size and costNegative air/Biofilter or positive aeration
Do composting emissions lead to harmful air
pollution?Compost piles emit Volatile Organic
Compounds (VOCs)When reactive VOCs mix with oxides of
nitrogen (NOx), in the presence of sunlight, photochemical “smog” results
Smog includes ground-level ozoneOzone very harmful to human health, also
damaging to plants and agricultureUS Clean Air Act regulates ozone levels,
mandates action to cut precursors like VOCs7
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California &the United States
1996-2002 Emissions Studies
Southern California—AQMD & CalRecycleFirst attempts in CA to quantify emissions
factors for composting facilitiesCalRecycle helped with concurrent testing
using lasers, and studied process controlsEmissions factors in mg of pollutant per kg
of feedstock
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VOC CH4 NH3
Biosolids 1205 8930 1525
Greenwaste 1880 435 410
AQMD data, average of two studies
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2005-6 CalRecycle StudyModesto - Northern California
70-80% of total VOCs emitted during 1st two weeks 70-85% of total VOC emissions vent through top of windrow “Pseudo-biofilter” compost cap reduced VOC emissions up to
75% for first two weeks. Additives reduced VOC emissions 42% for first week; 14% for
first two weeks 15% food waste roughly doubled VOC emissions compared to
“straight” green waste Lifecycle VOC emissions from pure greenwaste windrow
@450 mg/kg of feedstock
Pseudo-biofilter compost cap
15 cm layer of unscreened finished compost or overs on top of actively composting pile
Takes advantage of natural pile convectionCap layer
Active compost pile
AirflowAirflowWarm
pile core
2009 San Joaquin APCD study
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Study: Irrigation system used within 3 hours before turning reduced emissions by 24% over first 3 weeks
New Rule 4566: Facilities between 10,000-200,000 tons/year must achieve 24% reduction
Study: Pseudo-biofilter compost cap reduced emissions by 53% over first three weeks.
New Rule 4566: Facilities over 200,000 tpy must achieve 53% emissions reduction
2009-2011 Compost Emissions Reactivity Studies
Not all VOCs are equal; focus on ozone formation potential (OFP)
Compare modeled ozone formation to ozone measured in portable chamber
Tested OFP of windrows, tip piles, “overs”Tested impact on OFP of a pseudo-biofilter
cap made of composting “overs”Chamber method proven at many
agricultural sites in San Joaquin Valley13
Mobile Ozone Chamber
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Holds 1000-liter teflon bag3-hour experimentsUsed at many ag sites
Results from 3 studies
Compost VOC emissions 80-95% low OFP light alcohols: ethanol, methanol, isopropyl alcohol (2 butanol)
More than 80 other compoundsOzone formation potential (POCP):
Greenwaste composting mix: LOWBiosolids co-composting mix: LOW
Pseudo-biofilter overs cap reducedobserved ozone formation by 27-36%
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Maximum Incremental Reactivity scale (MIR)*
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*Similar to POCP
Comprehensive Compost Odor Response Project,
2007CalRecycle study, available on lineLiterature review on odor impacts of
temperature, C:N, moisture, aerationLaboratory test of mitigation strategiesMisting, odor neutralizers, oxygenators,
hydrogen peroxide, compost capPseudo-biofilter compost cap out-
performed all commercial preparations
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Too hot?DMDS: strong garlic odor
Too much woody material (carbon)?Terpenes
Too much grass or food (nitrogen)?Amines: smells fishy, putrid or dead
Too dense?Mercaptans:
smells like rotten cabbage
Not enough oxygen?More odors of all kinds
Lots of food?Volatile Fatty Acids: smells fecal, sweaty,
vinegar
Composting GHG study
Funded by CalRecycleResearch conducted by Univ. Calif.Focus on N20 and CH4
Field work 2010-2013Final report May, 2014Concurrent with and complementary
to other ongoing ag GHG studies19
Related Web Pages My CalRecycle web page:
http://www.calrecycle.ca.gov/Organics/Air/default.htm CalRecycle Greenwaste Compost Reactivity Study:
http://www.calrecycle.ca.gov/Publications/Organics/2011006.pdf CASA Biosolids Co-compost Reactivity Study
http://casaweb.org/documents/2011/werf2c10_web.pdf CalRecycle/Modesto Compost Study
http://www.calrecycle.ca.gov/publications/Organics/44207009.pdf Composting: Feedstock control vs. Aeration study
http://www.calrecycle.ca.gov/Publications/Organics/2008016.pdf Comprehensive Composting Odor Response Project
http://www.calrecycle.ca.gov/Publications/Organics/44207001.pdf
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Summary• Composting gives off VOCs• Emissions rates are highly variable• MIR / POCP for emissions is LOW• Composting VOCs around 1/3 as potent as
average urban air for ozone formation• Pseudo-biofilter compost cap effective in reducing
emissions and odors• Greenhouse gas impacts of composting need
further research
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Thank You
Bob Horowitz(916) 341-6523
[email protected]://www.calrecycle.ca.gov/Organics/Air/default.htm