A team of researchers, led by Dr Xiying Hao, Agriculture and Agri-Food Canada, Lethbridge Research and Development Centre, AB Canada, demonstrated the feasibility of co-composting construction and demolition (C&D) waste with cattle feedlot manure, and measured the related greenhouse gas (GHG) emissions.
Results are published in a scientific journal, Journal of Environmental Quality [1] and will be presented at the upcoming Livestock Waste Conference (August 10 to 12, Galway) [2].
Increased sustainable agricultural production is a priority for future food security. The North American livestock industry is increasingly replacing barley grain in cattle finishing diets with dried distillers’ grain with solubles (DDGS), an ethanol energy industry co-product. This practice derives more value for the bioenergy industry, while recycling nutrients in DDGS and reducing the land pressure for barley grain production.
Enteric CH4 emissions have been reduced or left unchanged following this use of DDGS [3, 4]. Increased N2O, but not CO2 and CH4, emission, during cattle manure composting has been reported when replacing 60% barley grain with wheat-based DDGS [5]. However, there were no changes in CO2, CH4 and N2O emissions when composting manure from cattle on diets with or without corn-based DDGS replacing 40% barley grain [6].
[caption id="attachment_31392" align="alignright" width="300"]
Figure 1. (a) Construction of straw-bale compost bin[/caption]
Landfills accounted for approximately 25.7% of total U.S. anthropogenic methane (CH4) emissions in 2014 [7] and 20% of Canadian CH4 emissions [8]. As much as one-third of the 20-million tonnes of solid waste in municipal waste streams is generated by construction, renovation and demolition activities in Canada [9]; thus, any diversion of construction and demolition (C&D) waste can potentially reduce CH4 emissions from landfills.
Recently, C&D waste, particularly the wood and drywall fractions, has been diverted to bed cattle feedlot pens in winter months instead of cereal straw or co-composted with livestock manure or paunch waste.
Availability of DDGS and need to recycle organic waste
With the increased availability of DDGS as cattle feed and the need to recycle organic waste, particularly C&D waste, Dr Hao and her colleagues conducted a field scale 99-day composting and manure storage experiment using two types of beef cattle feedlot manure (CK: typical western finishing diet containing 860g rolled barley grain, 100g barley silage,and 40g supplement kg-1 dry matter and DG: similar to CK, but with 300g kg-1 DM barley grain being replaced by corn DDGS).
The CK and DG manures were co-composted with (4:1) or without (5:0) C&D waste (treatments: CK_CD, DG_CD, CK and DG) in bins or stockpiled (treatments CK_st and DG_st) for 99 days.
Compost bins, each 13 m3 (2.50 m long × 2.22 m wide × 2.35 m high), were constructed by stacking rectangular shaped cereal straw bales (Fig 1a). Straw bales were used to construct relatively small bins in order to retain heat since limited DG manure was produced from the feeding trial. About 7 tonne (wet weight) of materials (averaging 1.75 m in height) were placed into each compost bin.
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Figure 1. (b) Foreground manure stockpile and background small bin composting[/caption]
Compost materials were turned using a front-end loader by flipping materials from one bin to an adjacent empty bin on Days 14, 37, and 64. The compost experiment was terminated on Day 99. For comparison, both CK and DG manure were also stockpiled for the same length of time as the composting treatments (Fig. 1b).
Adding C&D waste increased compost temperatures (0.4 to 16.3°C, average 7.2°C) over manure alone [1]. The final composts all had similar total C, total N, C/N ratio, and water-extractable K, Mg, and NO3- content. However, adding C&D waste increased water-extractable SO42- and Ca+ contents and decreased pH, total P (TP), water-extractable C, N, and P and most volatile fatty acids (VFA).
The GHG emissions over the 99-day composting were not affected by manure type (CK vs. DG manure). Composting with C&D waste produced similar CO2 emissions as without C&D, and both were higher than manure stockpiling. In contrast, CH4 emissions were reduced by the inclusion of C&D waste while the manure stockpile emitted the greatest amount of CH4. The N2O emissions were similar across all treatments [2].
The higher C&D compost temperatures should reduce pathogens while reduced VFA content should reduce odors. The lower CH4 emission with C&D waste is beneficial in reducing overall GHG emissions from manure composting.
When using the final compost product, the increased SO42- and reduced TP and available N and P content in C&D waste compost should be taken into consideration. Increased S content in C&D compost may be beneficial for some crops (e.g., canola) grown on S deficient soils.
The 2nd International Conference on Pollution Control and Resource Recovery for the Livestock Sector takes place in NUI Galway next month, providing a forum to present, discuss and develop innovative technologies and practices for managing livestock waste and recovering resources. Dr Xiying Hao will present on 'Impact of Nitrapyrin, N-(N-Butyl)-Thiophosphoric Triamide (NBPT) and Dicyandiamide (DCD) on N2O and CH4 emission from cow urine on a tame pasture' and also on 'Greenhouse gas emissions during co-composting of cattle feedlot manure with construction and demolition (C&D) waste'. For further information on Livestock 2016, click here or email Prof Xinmin Zhan at xinmin.zhan@nuigalway.ie.
References
1. Hao X, Hill B, Caffyn P, Travis G, Olson AF, Larney FJ, McAllister TA, Alexander T. Co-composting of beef cattle feedlot manure with construction and demolition waste.
Journal of Environmental Quality, 2014, 43:1799-1808.
2. Hao X, Larney FJ. Greenhouse gas emissions during co-composting of cattle feedlot manure with construction and demolition (C&D) waste. 2016 - Livestock Waste Conference, August 10 to 12, 2016, Galway, Ireland
3. Hünerberg M, Beauchemin KA, McGinn SM, Okine EK, Harstad OM, McAllister TA. Effect of dried distillers' grains with solubles on enteric methane emissions and nitrogen excretion from finishing beef cattle,
Canadian Journal of Animal Science, 2013, 93:373-385
4. Hünerberg M, Beauchemin KA, McGinn SM, Okine EK, Harstad OM, McAllister TA. Effect of dried distillers grains plus solubles on enteric methane emissions and nitrogen excretion from growing beef cattle.
Journal of Animal Science, 2013, 91: 2846-2857
5. Hao X, Benke, MB, Gibbs D, Stonge A, Travis G, and McAllister TA. Effects of dried distillers’ grains with solubles (wheat-based) in feedlot cattle diets on feces and manure composition.
Journal of Environmental Quality, 2009, 38:1709-1718.
6. Hao X, Benke MB, Li C, Larney FJ, Beauchemin KA, McAllister TA. Nitrogen transformations and greenhouse gas emissions during composting of manure from cattle fed diets containing corn dried distillers grains with soluble and condensed tannins.
Animal Feed Science and Technology, 2011, 166-167:539-549.
7. U.S. Environmental Protection Agency.
DRAFT Inventory of U.S. Greenhouse Gas 7 Emissions and Sinks: 1994-2014. Available online at
http://www3.epa.gov/climatechange/Downloads/ghgemissions/US-GHG-Inventory-2016-Main-Text.pdf
8. Environment Canada. Municipal Solid Waste and Greenhouse Gases. 2014, Available online at
http://www.ec.gc.ca/gdd-mw/default.asp?lang=En&n=6f92e701-1
9. Public Works and Government Services Canada. Chapter 8 - Construction, Renovation and Demolition Waste. In
The Environmentally Responsible Construction and Renovation Handbook. 2014,
available online here.
Contributing author:
Dr. Xiying Hao
Senior Research Scientist
Agriculture and Agri-Food Canada
Lethbridge Research and Development Centre
Lethbridge, AB Canada
Email: Xiying.hao@agr.gc.ca