Transcript Livestock Manure Treatment Technologies: Environmental Impacts

Livestock Manure
Treatment Technologies:
Environmental Impacts
Dr. Bruce T. Bowman
Chair, CARC Expert Committee on
Manure Management
April 30, 2002
Waterloo, Ontario
ManureNet
http://www.agr.gc.ca/science/initiatives/manurenet/
What is the Value of Manure?
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IF managed properly…
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Valuable recycled nutrient source
Excellent soil conditioner (biological)
IF managed poorly…
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Nuisance waste
 Environmental liability
Some History
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Manure issues have challenged farmers for
well over a century
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What has changed?
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Technology has advanced a lot … however …
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Same old issues …
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Odour
 Impacts on Water quality
What are the Major Issues?
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Odour intensity
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Pathogen levels
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Nutrient excesses
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Large water volumes
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Greenhouse gas emissions
Traditionally
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Manure has not been actively treated
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Exception – composting
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Solid manure piles
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Accidental curing – less odour, pathogens
The Current Situation
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Liquid systems - more popular since 1970’s
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labour-saving – OK for moderate-size operations
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Recent trends in livestock operations
 Great increase in herd size
 Geographic concentration
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Problem issues
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Increased odour
 Excess water volumes – land application
 Nutrient accumulations – P & N
Manure Treatment Technologies
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Constructed wetlands / filter strips
Solid-liquid separation
Composting
Digestion (anaerobic, aerobic)
Nutrient recovery/recycling
Value-added processing
Other Treatments
Constructed Wetlands / Filter Strips
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Benefits
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Polishing run-off waste water from barn/milkhouse
Reducing water volumes (evaporation)
Drawbacks
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Possible ghg emissions
Sediment buildup
Nutrient accumulations (P)
Significant area at farm site
Can’t handle high solids content
Solid-Liquid Separation
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Variety of screens, filters, presses, settling beds
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Benefits
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Reducing water volumes – reduced storage
Opportunities for nutrient partitioning
Flexibility of use - transportation
Drawbacks
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Possible problems if low solids content
 Cost – both liquid & solid handling equipment
Solid-Liquid Separation
Composting
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Benefits
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Reduce water volumes
Eliminate odour & pathogens, kill weed seeds
Mature compost - low risk for water contamination
Soil conditioner
Drawbacks
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More Labour-intensive
 Considerable ammonia losses (open composting)
 Possible GHG emissions (open composting)
Composting
Anaerobic Digestion
Odour
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Pathogens
GHGs
Closed vessel - greatly reduce odours
Ammonia emissions minimized
Surface application of digested manure?
 Suitable for No-till operations?
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Greatly reduced or eliminated
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Minimal GHG losses during treatment
Methane captured and utilized
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Anaerobic Digestion
Nutrients
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Closed vessel, nutrients conserved
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Increased N content; better N:P ratio
Neutral pH to reduce ammonia losses
Nutrients more available for plant use
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EcoEfficiency
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Methane captured - heat or electricity
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50% of carbon  methane
Recycled energy
“Green power”; distributed generation
Energy independence, revenue source
(power generation being privatized)
Anaerobic Digestion
Other Treatments
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Lagoon Additives (odour control)
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Generally not (cost)-effective at claimed rates
Ozonation
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Reduce odours in air & in manure slurries
Reduce pathogens in manure slurries
Nutrient Recovery / Recycling
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Phosphorus – “non-renewal” resource
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Re-cycle nutrients – sustainability issue
150 M t/yr P extracted & processed (85% Ag)
Flexibility for nutrient utilization
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On-farm – limited by land base, NMP (P, N)
Diverting off-farm, amendments/fertilizer
Nutrient Recovery / Recycling
Integrated Waste Management System
Integrated Farm Energy System (IFES)
Value-Added Processing
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Blending manure-based amendments
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Supplementing with mineral fertilizers
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Fertilizer vs amendment (guaranteed analysis)
Pasteurizing
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Adding back specific microbes (disease control)
Pelletizing
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Easier storage, transportation, application
Looking Ahead
Need to manage manure for:
 Soil conditioning value
 Nutrient value
 Energy content
 Value-added products
 Minimize negative environmental impacts
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Innovative partnerships for waste management
 Other Ag (food processors, rendering, deadstock)
 Municipal (residential wastes, sewage)
 Industrial (energy producers, commercial alcohol)
Conference Announcement
A National Conference and Exhibition on
Integrated Solutions to Manure Management:
Working Together on Challenges and Opportunities
Location: Convention Centre
London, Ontario
September 11-13, 2002
http://res2.agr.ca/initiatives/manurenet/ismm/