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  1. 1. 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 Horowitz California Dept. of Resources, Recycling & Recovery (CalRecycle)
  2. 2. This Presentation 1. Composting in California today 2. Do compost emissions lead to harmful air pollution? 3. Composting emissions research 4. Odor issues and research 5. Climate change research 2
  3. 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 >3 cubic meters of garbage per week must recycle NEW: Apartment buildings with 5 or more units must offer recycling to residents 3
  4. 4. 4 Open-windrow composting 20 hectare green waste facility near Modesto, CA
  5. 5. Composting in California Most facilities compost source separated green waste in open windrows 115 facilities / 4 million tonnes processed Most compost sold to agriculture, but farmers do not want to pay too much New air- and water-quality regulations will require facility upgrades better windrow management and engineered systems to capture volatile organic compounds and ammonia Economics do not support engineered facilities
  6. 6. $35 million Biosolids and bulking agents Indoor tipping and mixing areas Negative aeration; biofilter Synagro-Southern Kern County Outdoor ASP 85% VOC/ 99% NH3 Capture 455 tonnes/day
  7. 7. 7 Indoor ASP 95% VOC capture 99% NH3 capture 380 tonnes/day $80 million Biosolids and bulking agents Converted IKEA warehouse 8-12 air changes per hour  Negative aeration; 1.2 ha biofilter Inland Empire Utilities District - Rancho Cucamonga
  8. 8. Tarped, aerated systems 8 Micro-pore covers 80%-plus VOC & NH3 capture Scalable size and cost Negative air/Biofilter or positive aeration
  9. 9. 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 9
  10. 10. 10 Ozone non-attainment areas in the USA Source: USEPA 8-hour ozone (1997 standard) As of April, 2011
  11. 11. 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 Emissions factors in mg of pollutant per kg of feedstock 11 VOC CH4 NH3 Biosolids 1205 8930 1525 Greenwaste 1880 435 410 AQMD data, average of two studies
  12. 12. 12 2005-6 CalRecycle Study Modesto - 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
  13. 13. 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 AirflowAirflow Warm pile core
  14. 14. 2009 San Joaquin APCD study 14 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
  15. 15. 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 15
  16. 16. Mobile Ozone Chamber 16 Holds 1000-liter teflon bag 3-hour experiments Used at many ag sites
  17. 17. 17 Inside the MOChA chamber: UV light similar to summer day
  18. 18. Phase 1 study results Compost VOC emissions 80-95% light alcohols: ethanol, methanol, isopropyl alcohol (2 butanol) Light alcohols have low OFP More than 80 other compounds 1-3% highly reactive terpenes, aldehydes 18 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
  19. 19. 19
  20. 20. More 2010-2011 results Alcohols more than 90% of emissions MIR of greenwaste composting emissions mix:.9 - 1.5 - LOW MIR of biosolids co-composting emissions mix @1 - LOW Overs cap effective in reducing observed ozone formation by 27-36% 20
  21. 21. Maximum Incremental Reactivity scale (MIR)* 21 *Similar to POCP
  22. 22. VOCs and Odors Not all VOCs are odorous and not all composting odors are VOCs A lot of research but still subjective when it comes to what is offensive Odors issues are the single biggest threat to any composting operation California currently looking at its regulations to see whether there is a more objective way to handle odor complaints 22
  23. 23. Emissions & their odors Compounds Odors Aldehydes Sweet, pungent, green Amines Fishy, putrid, dead animals, ammonia, fertilizer Sulfur compounds Rotten eggs, cabbage, skunk, garlic Terpenes Fruity, pine, citrus, eucalyptus, menthol Volatile Fatty Acids Fecal, vomit, sweat, vinegar 23
  24. 24. Comprehensive Compost Odor Response Project, 2007 CalRecycle study, available on line Literature review on odor impacts of temperature, C:N, moisture, aeration Laboratory test of mitigation strategies Misting, odor neutralizers, oxygenators, hydrogen peroxide, compost cap Pseudo-biofilter compost cap out- performed all commercial preparations 24
  25. 25. 25 Too hot? DMDS Too much woody material (carbon)? Terpenes Too much grass or food (nitrogen)? Amines Too dense? Mercaptans Not enough oxygen? More odors of all kinds
  26. 26. Composting GHG study Funded by CalRecycle Research conducted by Univ. Calif. Focus on N20 and CH4 Field work 2010-2013 Final report May, 2014 Concurrent with and complementary to other ongoing ag GHG studies 26
  27. 27. Dual approach 27 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
  28. 28. 28 Increasing compost use… …may decrease use of less sustainable methods.
  29. 29. 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 29
  30. 30. 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 compost production and use need further research 30
  31. 31. Thank You Bob Horowitz (916) 341-6523