Air Emissions from Composting 10 YEARS OF RESEARCH AND REGULATORY ACTION IN CALIFORNIA Robert Horowitz California Dept. of Resources, Recycling & Recovery.

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

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Open-windrow composting

20 hectare green waste facility near Modesto, CA

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

Mobile Ozone Chamber

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Holds 1000-liter teflon bag3-hour experimentsUsed at many ag sites

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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Maximum Incremental Reactivity scale (MIR)*

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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

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Increasing compost use…

…may decrease use of less sustainable methods.

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