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

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Presentation on theme: "Air Emissions from Composting 10 YEARS OF RESEARCH AND REGULATORY ACTION IN CALIFORNIA Robert Horowitz California Dept. of Resources, Recycling & Recovery."— Presentation transcript:

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

2 This Presentation 1.California law and composting 2.Do compost emissions lead to harmful air pollution? 3.Air Pollution Control Districts 4.Composting emissions research 5.Climate change research 2

3 California Law  Cities and counties must divert >50% of their solid waste away from landfills or CalRecycle can issue fines  Composting IS recycling  NEW: CA recycling goal: 75% by 2020  NEW: Businesses with >4 cubic meters of garbage per week must recycle  NEW: Apartment buildings with 5 or more units must offer recycling to residents 3

4 Composting in California  Most facilities compost source separated green waste in open windrows  115 facilities / @4 million tons processed  Most compost sold to agriculture, but farmers do not want to pay too much  New air- and water-quality regulations will require major facility upgrades  Economics do not support engineered facilities

5 5 Open-windrow composting 20 hectare green waste facility near Modesto, CA

6 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 ozone  Ozone is very harmful to human health, as well as plants and agricultural crops  US Clean Air Act regulates ozone levels, mandates action to cut precursors like VOCs 6

7 7 Ozone non-attainment areas in the USA Source: USEPA 8-hour ozone (1997 standard) As of April, 2011

8 8 California Air Pollution Control Districts Districts enforce federal and state laws, including the Clean Air Act The association of top air district officials is called CAPCOA

9 APCDs and Composting  Two largest districts adopted rules in 2011  At 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 sites  New interpretation of rules regarding portable equipment 9

10 Common features of APCD rules  Enhanced record keeping: materials in & out and materials into windrows  Feedstock holding time limits  Wet top of windrow before turning  Pseudo-biofilter compost cap on active windrows. Replace the cap if you turn  Aerated systems with emissions capture for the largest facilities  Annual inspections 10

11 New Source Review in the SJV  Best Available Control Technology (BACT) required for :  Any new facility with VOC emissions greater than 10 tons per year  Any expanded facility with VOC increase greater than 2 pounds per day  SJV emissions factor 5.71 lbs of VOC per ton of greenwaste feedstock = 3500 tpy composting  You must purchase offsets for each ton of emissions over 10 tons per year 11

12 Yolo – Solano AQMD  Facilities grandfathered in at existing emissions set in baseline study  You can increase throughput but you cannot increase emissions  Source testing of new system to ensure emissions are reduced overall 12

13 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 violations 13

14 1996-2002 Emissions Studies Southern California—AQMD & CalRecycle  First attempts in CA to quantify emissions factors for composting facilities  CalRecycle helped with concurrent testing using lasers, and studied process controls  Established emissions factors in pounds of pollutant per ton of feedstock  Emissions factors allow APCDs to estimate emissions from a facility based on throughput 14

15 15 2005-6 CalRecycle Study Modesto - Northern California  70-80% of total VOCs emitted during 1 st 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

16 Pseudo-biofilter compost cap  15 cm layer of unscreened finished compost or overs on top of actively composting pile  Takes advantage of natural pile convection Cap layer Active compost pile Airflow Warm pile core

17 2009 San Joaquin APCD study 17 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

18 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  Proven method used at many agricultural sites in San Joaquin Valley 18

19 Mobile Ozone Chamber 19  Holds 1000-liter teflon bag  3-hour experiments  Used at many ag sites

20 What kinds of emissions?  80-95% light alcohols: ethanol, methanol, isopropyl alcohol  More than 80 other compounds  1-3% highly reactive terpenes, aldehydes 20 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

21 More 2010-2011 results  Reactivity of greenwaste and biosolids composting emissions: LOW  Overs cap effective in reducing observed ozone formation by 27-36%  Composting similar to other agricultural sources, such as manure  Typical urban air @3x more reactive than composting emissions 21

22 Maximum Incremental Reactivity scale (MIR)* 22

23 Composting GHG study  Funded by CalRecycle  Research conducted by Univ. Calif.  Focus on N 2 0 and CH 4  Field work 2010-2013  Final report May, 2014  Concurrent with and complementary to other ongoing ag GHG studies 23

24 Dual approach 24 1. Measure CH 4 and N 2 0 from composting windrows of green waste and food waste 2. Measure N 2 0 and CH 4 emissions from compost amended and conventionally fertilized croplands

25 25 Increasing compost use… …may decrease use of less sustainable methods.

26 Related Web Pages  My CalRecycle web page:  CalRecycle Greenwaste Compost Reactivity Study:  CASA Biosolids Co-compost Reactivity Study  CalRecycle/Modesto Compost Study  Composting: Feedstock control vs. Aeration study  Comprehensive Composting Odor Response Project 26

27 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 27

28 Thank You Bob Horowitz (916) 341-6523

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