Livestock Manure Treatment Technologies: Environmental Impacts
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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?
IF managed properly…
Valuable recycled nutrient source
Excellent soil conditioner (biological)
IF managed poorly…
Nuisance waste
Environmental liability
Some History
Manure issues have challenged farmers for
well over a century
What has changed?
Technology has advanced a lot … however …
Same old issues …
Odour
Impacts on Water quality
What are the Major Issues?
Odour intensity
Pathogen levels
Nutrient excesses
Large water volumes
Greenhouse gas emissions
Traditionally
Manure has not been actively treated
Exception – composting
Solid manure piles
Accidental curing – less odour, pathogens
The Current Situation
Liquid systems - more popular since 1970’s
labour-saving – OK for moderate-size operations
Recent trends in livestock operations
Great increase in herd size
Geographic concentration
Problem issues
Increased odour
Excess water volumes – land application
Nutrient accumulations – P & N
Manure Treatment Technologies
Constructed wetlands / filter strips
Solid-liquid separation
Composting
Digestion (anaerobic, aerobic)
Nutrient recovery/recycling
Value-added processing
Other Treatments
Constructed Wetlands / Filter Strips
Benefits
Polishing run-off waste water from barn/milkhouse
Reducing water volumes (evaporation)
Drawbacks
Possible ghg emissions
Sediment buildup
Nutrient accumulations (P)
Significant area at farm site
Can’t handle high solids content
Solid-Liquid Separation
Variety of screens, filters, presses, settling beds
Benefits
Reducing water volumes – reduced storage
Opportunities for nutrient partitioning
Flexibility of use - transportation
Drawbacks
Possible problems if low solids content
Cost – both liquid & solid handling equipment
Solid-Liquid Separation
Composting
Benefits
Reduce water volumes
Eliminate odour & pathogens, kill weed seeds
Mature compost - low risk for water contamination
Soil conditioner
Drawbacks
More Labour-intensive
Considerable ammonia losses (open composting)
Possible GHG emissions (open composting)
Composting
Anaerobic Digestion
Odour
Pathogens
GHGs
Closed vessel - greatly reduce odours
Ammonia emissions minimized
Surface application of digested manure?
Suitable for No-till operations?
Greatly reduced or eliminated
Minimal GHG losses during treatment
Methane captured and utilized
Anaerobic Digestion
Nutrients
Closed vessel, nutrients conserved
Increased N content; better N:P ratio
Neutral pH to reduce ammonia losses
Nutrients more available for plant use
EcoEfficiency
Methane captured - heat or electricity
50% of carbon methane
Recycled energy
“Green power”; distributed generation
Energy independence, revenue source
(power generation being privatized)
Anaerobic Digestion
Other Treatments
Lagoon Additives (odour control)
Generally not (cost)-effective at claimed rates
Ozonation
Reduce odours in air & in manure slurries
Reduce pathogens in manure slurries
Nutrient Recovery / Recycling
Phosphorus – “non-renewal” resource
Re-cycle nutrients – sustainability issue
150 M t/yr P extracted & processed (85% Ag)
Flexibility for nutrient utilization
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
Blending manure-based amendments
Supplementing with mineral fertilizers
Fertilizer vs amendment (guaranteed analysis)
Pasteurizing
Adding back specific microbes (disease control)
Pelletizing
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
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/