air emissions from composting 10 years of research and regulatory action in california robert...
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Air Emissions from Composting
10 YEARS OF RESEARCHAND REGULATORY ACTION
IN CALIFORNIARobert Horowitz
California Dept. of Resources, Recycling & Recovery (CalRecycle)[email protected]
This Presentation1. California law and composting2. Do compost emissions lead to harmful air
pollution?3. Air Pollution Control Districts4. Composting emissions 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 >4 cubic meters of
garbage per week must recycleNEW: Apartment buildings with 5 or more units
must offer recycling to residents
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Composting in California
Most facilities compost source separated green waste in open windrows
115 facilities / @4 million tons processedMost compost sold to agriculture, but farmers do
not want to pay too muchNew air- and water-quality regulations will
require major facility upgradesEconomics do not support engineered facilities
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 is very harmful to human health, as
well as plants and agricultural cropsUS Clean Air Act regulates ozone levels,
mandates action to cut precursors like VOCs6
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Ozone non-attainment areas in the USA
Source: USEPA
8-hour ozone (1997 standard) As of April, 2011
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California Air
Pollution Control
Districts
Districts enforce federal and state laws, includingthe Clean Air Act
The association of topair district officials is calledCAPCOA
APCDs and Composting
Two largest districts adopted rules in 2011At least one other has a compost rule on its
calendar for 2012 (Ventura)CAPCOA survey asking all districts if they don’t
regulate composting-why not?San Joaquin now enforcing New Source Review
for new/expanded compost sitesNew interpretation of rules regarding portable
equipment9
Common features of APCD rules
Enhanced record keeping: materials in & out and materials into windrows
Feedstock holding time limitsWet top of windrow before turningPseudo-biofilter compost cap on active windrows.
Replace the cap if you turn Aerated systems with emissions capture for the
largest facilitiesAnnual inspections
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New Source Review in the SJV
Best Available Control Technology (BACT) required for :Any new facility with VOC emissions greater than 10
tons per yearAny expanded facility with VOC increase greater than 2
pounds per daySJV emissions factor 5.71 lbs of VOC per ton of
greenwaste feedstock = 3500 tpy compostingYou must purchase offsets for each ton of
emissions over 10 tons per year11
Yolo – Solano AQMDFacilities grandfathered in at existing
emissions set in baseline studyYou can increase throughput but you cannot
increase emissionsSource testing of new system to ensure
emissions are reduced overall
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Portable equipment permitting
Equipment essential to operation of composting facility is NOT portable
ARB tightened emissions standards for portable diesel equipment
Hundreds of grinders and trommels registered with ARB as portable, some incorrectly
CAPCOA seeking consistent application of stringent portability standard
APCDs can and will issue violations13
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 controlsEstablished emissions factors in pounds of pollutant per ton of
feedstockEmissions factors allow APCDs
to estimate emissions from afacility based on throughput
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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 1 lb
per ton 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 for 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, oversTested impact on OFP of a pseudo-biofilter
cap made of composting oversProven method used at many agricultural
sites in San Joaquin Valley18
What kinds of emissions?80-95% light alcohols: ethanol, methanol,
isopropyl alcoholMore than 80 other compounds1-3% highly reactive terpenes, aldehydes
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TOP COMPOUNDS IN COMPOSTING EMISSIONS•Isopropyl alcohol•Ethanol•Methanol•Acetic Acid•Limonene
•Camphor•Alpha Pinene•3 hydroxy 2 butanone•Butanoic acid
•Eucalyptol•Methylthymyl ether•Bornyl acetate•Pinene isomer
More 2010-2011 results
Reactivity of greenwaste and biosolids composting emissions: LOW
Overs cap effective in reducingobserved ozone formation by 27-36%
Composting similar to other agricultural sources, such as manure
Typical urban air @3x more reactive than composting emissions
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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 studies23
Dual approach
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1. Measure CH4 and N20 from composting windrows of green waste and food waste
2. Measure N20 and CH4 emissions from compost amended and conventionally fertilized croplands
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• Air pollution regulators are increasingly aware of
composting sites as emissions sources• Both pile emissions and equipment will face
increasingly stringent limits• 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 compost production and
use need further research
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Thank You
Bob Horowitz(916) 341-6523
[email protected]://www.calrecycle.ca.gov/Organics/Air/default.htm