Greenhouse Gas Emission Reduction through Composting

by

Kirstin Castro-Wunsch, P.Eng., Principal of KC Environmental Group Ltd.

 Cassandra Ng-Grondin, P.Eng., M.Eng., KC Environmental Group Ltd.

 

ABSTRACT

 

 

 

 

Climate change is one of the most challenging environmental, economic and social issues facing the world today. Increased man-made greenhouse gases that have increased substantially over the past century due to industrialization have contributed greatly to this issue. In Canada, methane emissions account for about 12.6 % of Canada's CO2 equivalent greenhouse gas emissions. Of these emissions 23.5 % come from landfills.  As such, landfills are Canada's fifth largest source of CO2 equivalent greenhouse gas emissions. In an effort to reduce the risk of future climate change and its voluntary commitment to improve the environment, KC Environmental Group Ltd. (KC) has identify an alternative method of waste processing for industrial and municipal organic wastes - Composting. KC undertook a two-year IRAP (Industry Research Assistance Program) project in 1998 that looked at composting of pulp sludge, wood waste and wood ash from the forest industry. In the same year, KC started a composting operation in West Edmonton - Cleanit   Greenit  (CG)  Composting  System. Germination test results from the IRAP Projects have shown that compost products used as soil amendments are comparable to peat. Growth trials with compost from CG also show that matured finished compost is slightly beneficial to growth and does not hinder plant growth. CG recognizes the potential value of its organic waste composting system to reduce GHG emissions (primarily methane) resulting from current landfilling of organic wastes. Operating at full capacity (20,000 tonnes per year) the CG Composting System at the current facility can reduce CO2 equivalent emissions by approximately 24,000 tonnes over the next 10 years, based on a first order decay model from IPCC Guidelines for National Greenhouse Gas Inventories. Composting not only transforms organic wastes which are otherwise considered wastes, into nutrient rich soil amendments, but also diverts the organic wastes from landfill. Although no verified measures for GHG reduction through composting are available to date, collaborative research is being carried out with University of Alberta researchers at CG Facility one beginning in January, 2001. Once a standard measurement for GHG emission reductions arising from the use of composting is established, other composters will be encouraged to claim emissions reduction. From this there may be the potential for the sale of credits for GHG emission reductions arising from the use of composting. Emission trading provides a market incentive to reduce emissions and it gives emitters more options to meet environmental objectives. Emission trading can help composting gain in popularity and promote other related waste minimization options. In order to address the global climate change issue, a mix of voluntary, regulatory and fiscal initiatives are necessary and emission trading could be a key element of Canada's efforts to address this issue. 

 

 

1. INTRODUCTION

 

Greenhouse Effect

 

The atmosphere contains greenhouse gases including carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), chlorofluorocarbons (CFCs) as well as water vapour (H2O) and ozone (O3). Not all greenhouse gases are produced by human activities. Some of these greenhouse gases (CO2, H2O and O3) occur naturally in our environment and trap heat near the Earth's surface and prevent it from escaping into space. These greenhouse gases provide insulation to the planet and make the earth's surface about 35oC warmer than it otherwise would be. These gases have the effect of making the escape of energy to space more difficult than it would be in a clear, dry atmosphere1.

 

Without these greenhouse gases, the world would be a very cold place to live. However, there is a growing concern about increasing greenhouse gas emissions caused by human activities and the impact on the Earth's climate.  These gases trap and absorb the energy that warms the atmosphere. An increase in the greenhouse gases causes an increase in absorption of energy and a net increase in the earth's temperature, creating the greenhouse effect.

 

Canada's Energy Outlook estimates that Canada emitted 599 CO2 equivalent megatonnes in 1990 and predicts that emissions will rise to 703 megatonnes by 2010. Ontario and Alberta are Canada's largest contributors to greenhouse gas emissions. The primary cause of Ontario's emissions is consumption of energy, while Alberta's is the production of energy. The NAPCC (National Action Program on Climate Change) in 1995 projected a 13% growth in Canada's GHG emissions from 1990 to 2000 unless there  are  new initiates undertaken 2.

 

Kyoto Protocol

 

In December of 1997, Canada and more than 150 countries reached agreement on the Kyoto Protocol, in Kyoto, Japan which sets binding limits on greenhouse gas (GHG) emissions from industrialized countries. Under its commitment made in Kyoto, Japan, the Canadian federal government has promised that by year 2012 it will reduce emissions by six per cent below year 1990's level.  The countries will meet to discuss further issues related to GHG emissions in the  summer of year 2001.

 

 

2. BACKGROUND

 

Greenhouse Emissions From Landfill

 

The solid waste source category produces significant GHG emissions; the most important of which is methane (CH4).  About 10% of global methane emissions from human-related sources are emitted from landfills and open dumps annually3. The IPCC (Intergovernmental Panel on Climate Change) states that overall emissions from solid waste are projected to grow significantly in the future. In Canada, methane emissions account for about 12.6 % of Canada's CO2 equivalent GHG emissions.  Of these emissions 23.5 % come from landfills. As such, landfills are Canada's fifth largest source of CO2 equivalent GHG emissions4. 

 

KC 's Cleanit Greenit (CG) Composting System

 

KC  Environmental     Group   Ltd. (KC)   is an Alberta-based environmental engineering firm that has as its prime objective the development of projects that promote both business and environment.   In an effort to reduce the risk of future climate change and its voluntary commitment in improving the environment, KC has identified an alternative method of waste processing for industrial and municipal organic wastes-Composting. KC's Cleanit Greenit (CG) Composting System is a technology that reduces greenhouse gas emissions and is at the same time economically viable. According to IPCC, emissions may be reduced by 30 to 50% through solid waste source reduction methods such as composting and through methane recovery methods.

 

3. DEVELOPMENT OF CLEANIT   GREENIT  COMPOSTING SYSTEM

 

Industrial Research Assistance Project (IRAP) Pilot Project

 

KC undertook a two-year Industry Research Assistance Program (IRAP)  pilot project in July of 1998 that looked at composting of pulp and paper sludge, wood residuals and wood ash from the forest industry.   Pulp and paper sludge is a significant by-product in the paper making industry worldwide. Traditionally, pulp and paper sludges are either landfilled or land applied as soil amendments or conditioners. However, land applications of the untreated pulp and paper has been a concern due to the odour, potential phytotoxicity5,6 (introduction of toxic materials into the plant that results in the death or impaired growth of the plant), and can only be applied seasonally.

 

The key objective of the IRAP pilot project is to develop processes that will best utilize the properties of a chemi-thermochemical pulp sludge and the wood residuals to produce an "A" grade compost defined by Canadian Council of Ministers of the Environment, Guidelines for Compost Quality (CCME, 1996). Grade A compost is virtually suitable for any use, according to the CCME guidelines.

 

In addition to transforming the above wastes into an "A" grade compost, the pilot project also provided useful information about the composting processes under seasonal and weather variations at the field scale. The data collected was used in the development of the CG Composting System.

 

Finished Product

 

The compost piles for the IRAP field pilot project were constructed by mixing one portion of a chemi-thermochemical pulp sludge with one and a half portion of wood residuals by volume. The compost piles had a length of 21m, a width of 5m, and a height of 2m. The compost piles were composted for about nine  months  with  occasional  turnings ( four times during the nine months) by a front-end loader. Wood chips of size ranging from 2 to 1.5 inches were used as porosity for aeration.

 

After nine months of composting, it was concluded that it is possible to compost the pulp sludge in extreme cold winter and the finished compost met the Grade "A " compost criteria defined by CCME guideline, as shown in Table 1. Oxygen uptake test showed that the finished compost with an oxygen uptake rate of 26 mg O2/kg was stabilized, when compared to the CCME criteria (oxygen uptake, shall be <150 mg O2/kg volatile organic solid per hour).

 

Table 1. Comparison of trace element concentrations in the finished compost with CCME criteria for grade " A" compost.

 

 

 

 

 

Category A

Category B

IRAP compost

Trace elements

 

mg per kg dry weight

 

Arsenic (As)

13

75

1.1

Cadmium (Cd)

3

20

0.672

Cobalt (Co)

34

150

2.15

Chromium (Cr)

210

1060

8.25

Copper (Cu)

100

757

12.2

Mercury (Hg)

0.8

5

0.01

Molybdenum (Mo)

5

20

0.69

Nickel (Ni)

62

180

5.23

Lead (Pb)

150

500

2.8

Selenium (Se)

2

14

0.42

Zinc (Zn)

500

1850

81

Growth Performance of Finished Compost (IRAP) Versus Peat

 

In September of 1999, a greenhouse experiment was conducted to determine the performance of various compost/peat/perlite mixes relative to a standard peat/perlite (75%/peat/25% perlite) mix. The different mix ratios are shown in Table 2.

 

Table 2. Different mix ratios for the growth trials

Treatment

Compost

Peat

Perlite

1

75%

0%

25%

2

50%

25%

25%

3

37.5%

37.5%

25%

4

25%

50%

25%

5 (control  sample )

0%

75%

25%

 

 

Performance was assessed through (1) germination; and (2) growth measured as above ground dry biomass of Phaseolus vulgaris var. "Tendergreen". The results for the germination and the above ground growth with the finished compost from the IRAP pilot project had the following conclusions:

 

(a)    There is no significant difference in timing of germination for all treatments after day eleven between the compost/peat/pertlite mixes and the 75% peat/25% perlite mix.

 

(b)   There are no significant differences for growth between mix ratios.

 

(c)    There are no significant differences for growth between the compost/peat/perlite  mix and the 75% peat/25% perlite mix, and the finished compost did not hinder the plant growth.

 

 

4. START UP OF CLEANIT GREENIT COMPOSTING SYSTEM

 

In November of 1998, KC started a composting operation in West Edmonton - CG Composting System facility one. The CG site is registered with Alberta Environmental Protection as a Class I composting facility to compost non-hazardous organic wastes and meets the standards required by the Alberta Energy and Utilities Board to treat suitable hydrocarbon contaminated materials.  Industrial wastes come from many sources including breweries, refineries, pulp mills, grocery stores, restaurants and landscapers. Municipal wastes come from leaf/yard collection, food residuals from residents, wood residuals and bio-solids from wastewater treatment plants.

 

CG Composting System is actively converting these organic wastes into high-grade compost.  Applications for the compost still continue to be developed and all compost manufactured has been sold under the Organic Soil trademark held by KC.

 

Growth Trials of CG Finished Compost

 

Incorporation into plant growth media is a good potential niche for entry of finished compost into the marketplace7.  In December of 1999, some of the first batches of CG compost blends were tested to determine their suitability for plant growth as a general purpose lawn and garden mix.  Six blends, as listed in Table 3, containing different proportions of compost, soil, and in some cases sand and wood ash, were compared to soil alone as well as a typical peat-based garden mix. The growth trial was done in three plant species: bean (Phaseolus vulgaris), marigold (Tagetes sp.) and Kentucky bluegrass (Poa sp.).

 

Table 3.  Different compost based blends

 

Treatment

Top soil

compost

sand

peat

Wood ash

1

100%

 

 

 

 

2

60%

 

20%

20%

 

3

60%

20%

20%

 

 

4

75%

25%

 

 

 

5

66.6%

33.3%

 

 

 

6

57%

20%

20%

 

3%

7

72%

25%

 

 

3%

8

63.6%

33.3%

 

 

3%

Note: All components except the wood ash were sieved using a 1/4" screen prior to blending.

 

 

Germination, height, flower initiation and production (for bean and marigold) as well as fresh and dry weights of above ground plant matter were parameters recorded. The followings were the conclusions of the study:

 

(a)    Plants of all three species fared equally well or slightly better in compost-based mixes as compared to treatments of soil alone or the peat-based garden mix, as shown in Figures 1, 2 and 3.

 

(b)   Few statistically significant differences could be seen in the experiments.

 

(c)    enerally, fresh and dry weights of marigold were notably lower in the peat-based mixture than the other treatments included in the experiment.

 

(d)   Among the six compost-based blends, there was no single one standing above the rest. 

 

(e)    All of them supported vigorous, healthy, dark green growth in bean,      marigold and Kentucky bluegrass.

(f)     The matured finished compost is slightly beneficial to growth and does not hinder plant growth.

 

This data has been used as a basis for improving product recipes and in development of CG’s current organic soil product line such as Nature Made Compost as well as Lawn and Garden Mix.

 

 

 

5. REDUCTION OF GHG AS A RESULT OF THE CG COMPOSTING SYSTEM PROJECT

 

In order to measure the reductions in GHG that would occur as a result of the CG Composting System Project, it is necessary to compare the Emission Reduction Case (CG Composting Systems Project) with the Reference case (the emissions that would occur if the project is not implemented).

 

RE = RC - ER

 

where

RE   =   Reductions in Emissions

RC = Emissions occurring in        Reference Case

ER = Emissions occurring in Emission Reductions Case

 

Emissions Reduction Case

 

The process of active, aerobic composting generates heat, carbon dioxide (CO2) and water vapour8. It is assumed that of the three major greenhouse gases, only CO2 is produced during composting. This would be true if aerobic conditions could be maintained throughout the entire composting process. In reality, this is very difficult to achieve unless the process is under the most closely controlled conditions.

 

The carbon dioxide that is emitted through composting is not included in the IPCC greenhouse gas emissions inventories. The CO2 that is produced in composting is derived from the decomposition of biomass sources (e.g. crops, forests). Since these biomass sources are regrown on an annual basis these CO2 emissions are not treated as net emissions from waste in IPCC Methodology 9.

 

Based on the above major assumptions and methodology, the GHG emissions resulting from the CG project are close to zero or negligent  (ER=0).

 

Reference Case

 

The Reference Case for this project is the emissions that would result without its development. The waste that is not composted through this project would be sent to a landfill. These landfills are typically small where methane gas recovery projects are not viable.

 

The primary GHG resulting from landfill is mostly methane, as a result of anaerobic (without air) decomposition of the organic fraction of waste in landfills. Therefore, RC=methane emissions from landfills .

 

Reduction Emissions from CG Composting System Facility One

 

CG Composting System Inc. in Edmonton, Alberta currently has the capacity of diverting about 20,000 tonnes of these organic wastes from landfills. Operating at full capacity the CG Composting System at the current facility can reduce CO2 equivalent emissions by approximately 24,000 tonnes over the next 10 years. CG Composting System Inc. blends different types of organic industrial and municipal wastes under specific controlled conditions. This process diverts these organic wastes which would normally be sent for landfilling where the anaerobic decomposition would lead to GHG releases mainly in the form of methane, a potent greenhouse gas.

The 24,000 tonnes reduction of CO2  equivalent emissions over the next 10 years is based on the first order decay model, QT,X=KRXLo exp-k(T-X), from the revised 1996, IPCC Guidelines for National Greenhouse Gas Inventories.

 

where:

 

QT,X      = the amount of methane CH4        generated in the current year (T) by the waste Rx

X         =   the year of waste input

Rx        =  the amount of waste disposed  in  year x (Mg)

T          =   the current year

K         =   methane generation

            rate constant (l/y): 0.006

Lo        = methane generation potential (m3/Mg of refuse): 200 (ranged from 100 to over 200)

 

The use of composting has the apparent advantage of reducing greenhouse gas emissions because the CO2 produced during composting has a much lower global warming potential than the CH4 that would be produced if material was put in landfill10. The CG System reduces GHG in three ways:

 

(a)    reduces methane emissions by diverting waste from landfills.

 

(b)   compost use minimizes the need for fertilizer thereby reducing N2O emissions.

 

(c)    compost use increases soil moisture retention which reduces the amount of energy needed for irrigation thereby reducing CO2 emissions.

 

 

 

Verification of GHG reductions through composting

 

KC Environmental Group is committed to verifying the actual emissions reduced through the CG System. Although no verified measures for GHG reduction through composting are available to date, collaborative research is being carried out with University of Alberta researchers at CG site beginning in January, 2001.

 

Compost piles built in the normal course of operations at CG in Edmonton will be monitored for GHG emissions.  At least three piles will be monitored so that the monitoring periods include both warm weather and cold weather conditions for similar substrate materials. Monitoring will be carried out using a static chamber technique. Gas samples taken using this technique will be analyzed using gas chromatography at the University of Alberta. Temperature and oxygen content in the piles will be monitored daily using a hand-held probe.

 

Once a standard measurement for GHG emission reductions arising from the use of composting is established, other composters will be encouraged to claim emissions reduction.

 

 

EMISSION REDUCTION TRADING

 

Emission trading is an initiative that can successfully reduce GHG without seriously affecting the economy. Emission reduction trading provides GHG emitters the flexibility to seek out lower-cost emission reductions in other operations.

 

A typical GHG emission reduction trade occurs when a buyer with high cost options for emission reduction purchases a lower cost option from a seller and enters into a contract to transfer ownership of the emission reduction. This causes emission reductions to occur where they are least costly, thereby lowering the cost of reducing GHG emissions generally or meeting a given target. Subsequently there is a potential for the sale of credits for (GHG) emission reductions arising from the use of composting.

 

Emission trading provides a market incentive to reduce emissions and it gives emitters more options to meet environmental objectives. Emission trading can help composting gain in popularity and promotes other related waste minimization.

 

In order to address the global climate change issue, a mix of voluntary, regulatory and fiscal initiatives is necessary and emission trading could be a key element of Canada's efforts to address this issue.

 

Though technological control of the CO2 buildup seems difficult, every effort should be made to do so if there is a need to slow down carbon accumulation in the atmosphere. In fact, composting not only reduces methane emissions, the compost product can reverse the loss of soil humus that is affecting some agricultural areas.

 

 

 

ACKNOWLEDGEMENT

 

The author would like to give thanks to IRAP for the financial support, to Mrs. Karen Castro (MSc. in Conservation Biology) for her growth trial and analysis information and to Mrs. Kirstin Castro-Wunsch, P.Eng., Principal of KC Environmental Group Ltd, for the review of this paper.

 

REFERENCES

 

1.      Henry, J.G. and G.W.Heinke. 1989. Environmental Science and Engineering, Prentice-Hall, Inc. Englewood Cliffs, New Jersey. Pg. 212-220.

 

2.      Alberta Economic Development Authority, Climate Change Round Table - Workbook.

 

3.      IPCC: Technologies, Policies, and Measures for Mitigating Climate Change, November, 1996.

 

4.      Canada's Second National Report on Climate Change, "Actions to meet commitments under the United Nations Framework Convention on Climate Change", Environment Canada Report En21-125/1997E, November, 1997.

 

5.      Jackson, M.J. and M.A.Line. 1997. Composting Pulp and Paper Mill Sludge - Effect of Temperature and Nutrient Addition Method. Compost Science and Utilization 5(1): 74-81.

 

6.      Campbell, A.G., X.Zhang and R.R. Tripepe. 1995. Composting and evaluating a pulp and paper sludge for use as a soil amendment/mulch. Compost Science and Utilization 3(1): 84-95.

 

7.      Mathur, S.P. and B. Voisin. 1996. The Use of Compost as a Greenhouse Growth Media. Final Report of a Study Conducted for Waste Reduction Branch, Ontario Ministry of Environment and Energy at the Composting Council of Canada.

 

8.      On-Farm Composting Handbook. 1992. Edited by R.Rynk. Northeast Regional Agricultural Engineering Service, Ithaca, New York.

 

9.      Revised 1996, IPCC Guidelines for National Greenhouse Gas Inventories: Reference Manual, Chapter 6. 6.1.

 

10.  Janzen, H.H., R.L. Desjardins, J.M.R. Asselin and B. Grace. 1999.  The Health of Our Air - Toward sustainable Agriculture in Canada. Agriculture and Agri-Food Canada, Ottawa, Ontario.