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)robert.horowitz@CalRecycle.ca.gov

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

Robert.Horowitz@CalRecycle.ca.govhttp://www.calrecycle.ca.gov/Organics/Air/default.htm