ANAEROBIC TREATMENT OF PIGGERY SLURRY

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ANAEROBIC TREATMENT OF PIGGERY SLURRY

• D. P. Chynoweth
• A. C. Wilkie
• J. M. Owens

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SCOPE OF PRESENTATION

• production of swine wastes
• characteristics of swine wastes
• environment impact
• anaerobic processing options
• residue use
• biogas use
• future trends

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WORLD SWINE POPULATION BY REGION
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GEOGRAPHIC PRODUCTION OF SWINE IN THE U.S.
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WORLD SWINE WASTE PRODUCTION BY REGION
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FUTURE TRENDS IN SWINE AND SWINE WASTE PRODUCTION

• pork consumption is increasing in developing
  countries (especially in China and India)
• piggeries are larger and more centralized, often
  gt1,000 -10,000
• wastes exceed capacity for land disposal without
  several environmental impact

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OVERVIEW OF SWINE PRODUCTION FACILITIES
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OVERVIEW OF SWINE PRODUCTION FACILITIES
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GLOBAL SWINE WASTE MANAGEMENT SYSTEMS
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TYPICAL BODY MASS AND WASTE PRODUCTION (per day
per 1000 kg)
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ENVIRONMENTAL IMPACT OF SWINE WASTES

• organic matter
• inorganic nutrients
• gases, dusts, and aerosols (health effects)
• greenhouse gases
• odors

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ENVIRONMENTAL IMPACT OF ORGANIC MATTER

• oxygen demand in receiving waters
• untreated wastes attract pests when land applied
• imbalanced anaerobic decomposition produces odors
• decomposition releases greenhouse gases (CH4,
  CO2, NOx)

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LAWS, REGULATION, AND POLICY (Clean Water Act)

• addresses national air quality
• concerned with point sources pollution
• e.g., Category 1 applies to 2500 sine confined
  for 45 days per year requires NDPES permit
• smaller systems may be required to use Best
  Available Technology (BAT) and Best Conventional
  Pollutant Control Technology (BCPCT)

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LAWS, REGULATION, AND POLICY (Clean Air Act)

• national air quality
• methane, ammonia, dust

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LAWS, REGULATION, AND POLICY (Coastal Zone Act
Reauthorization Amendments)

• regulates animal operations in 35 coastal states
• requires storage and treatment of wastewater and
  stormwater, waste treatment, and nutrient
  management
• existing swine facilities under this act have
  100-200 head

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ENVIRONMENTAL IMPACT OF NITROGEN AND PHOSPHORUS

• eutrophication of receiving waters
• nitrates in groundwater (USEPA std. Is 10 mg/L)
• ammonia may be toxic to aquatic organisms (USEPA
  std. is 0.02 mg/L)
• N and P stimulate toxic algae blooms (e.g.
  Pfiesteria)
• oxides of nitrogen cause acid rain and contribute
  to global warming

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TOXIC ALGAE PFIESTERIA

• toxic diatom
• leathal to aquatic organisms
• toxic to humans and other animals
• caused by inorganic nutrients in brackish waters

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HEALTH EFFECTS OF AEROSOLS

• ammonia causes eye irritation, respiratory
  problems, and other illness (recommended level is
  10- ppm)
• hydrogen sulfide odor is detectable at 0.005 ppm,
  causes nausea at 50-500 ppm, and is lethal at
  1000 ppm
• pathogens include organisms that cause
  salmonellosis, Q fever, Newcastle disease,
  histoplasmosis, cryptosporidiosis, and gardiasis
• allergies related to particulates in air

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ODORS

• a major problem with piggeries
• affects animals, workers, and is a nuisance to
  nearby dwellings
• causes by hydrogen sulfide, ammonia, and numerous
  organic compounds produced by imbalance anaerobic
  decomposition

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ADVANTAGES OF ANAEROBIC DIGESTION

• low energy requirements
• less sludge production
• low nutrient requirements
• can handle loading variations (hydraulic and
  organic)
• reduces pathogens
• survives dormant periods
• produces methane

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POTENTIAL APPLICATIONS OF ANAEROBIC PROCESSING
FOR SWINE WASTES

• flushed slurries
• scraped solids
• separated solids and slurries
• biological nutrient removal
• denitrification
• phosphorus

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PRINCIPAL REACTIONS OF BALANCED BIOMETHANOGENESIS
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PRINCIPAL REACTIONS OF IMBALANCED METHANOGENESIS
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SWINE WASTE CHARACTERISTICS FROM STORAGE TANKS
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SWINE WASTE CHARACTERISTICS FROM
STORAGE/TREATMENT FACILITIES
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ANAEROBIC DIGESTIBILITY OF SWINE WASTE
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ENVIRONMENTAL BENEFITS OF ANAEROBIC DIGESTION

• significantly reduces carbon dioxide and methane
  emissions
• eliminates odors
• produces sanitized compost and nutrient-rich
  fertilizer
• maximizes recycling benefits

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ENERGY BENEFITS OF ANAEROBIC DIGESTION

• net energy producing process
• generates high quality renewable fuel
• biogas proven in numerous end-use applications

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FACTORS INFLUENCING REACTOR DESIGN

• chemical characteristics of feed
• concentration of biodegradable matter
• concentration of feed particulate solids
• scale of application
• continuity of feed availability
• desired products
• site

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ANAEROBIC DIGESTER DESIGNS FOR DIFFERENT
FEEDSTOCKS
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OPERATING PARAMETERS

• loading rate
• start-up
• temperature
• nutrients
• mixing
• inhibition

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PERFORMANCE PARAMETERS

• gas and methane yields and production rates
• organic matter reduction (VS, COD)
• organic acids, pH, alkalinity

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PERFORMANCE PARAMETERS
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ANAEROBIC DIGESTER DESIGNS
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ANAEROBIC DIGESTER DESIGNS
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ANAEROBIC DIGESTER DESIGNS (SBR)
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ANAEROBIC LAGOON
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BULK VOLUME FERMENTOR
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CRITICAL CONCENTRATIONS OF INHIBITORS
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EFFECT OF AMMONIA NITROGEN ON ANAEROBIC DIGESTION
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RESIDUE USE CONSIDERATIONS

• use as compost
• high in inorganic nutrients
• improves water retention
• low odor levels
• pathogens
• mesophilic digestion gives poor reduction
• thermophilic digestion give good reduction
• best to maintain at 70oC for one hour
• should cure prior to use as compost
• removes volatile acids and sulfides
• use for refeeding (solids contain 14 protein)

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EFFLUENT TREATMENT (Goals)

• organics (BOD)
• odor
• nutrients
• pathogens

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EFFLUENT TREATMENT (Methods 1)

• aerobic treatment
• polishing of organics
• nitrification
• phosphorus uptake
• anaerobic treatment
• denitrification
• enrichment of volatiles acids to enhance
  phosphorus removal

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EFFLUENT TREATMENT (Methods 2)

• Plant Systems
• oxidation ponds
• constructed wetlands
• Physical Treatment
• sedimentation, screening, centrifuging
• Chemical Treatment
• phosphorus precipitation
• disinfection

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IMPROVING NET ENERGY

• components in order of importance are feed
  heating, heat losses, and mixing
• large feed heating requirement is a strong
  incentive for operation of dilute feed systems at
  ambient temperatures
• range from 10-100 of methane product
• high-solids systems conserve energy (may be self
  heating)

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ODORS (1)

• gt75 compounds formed under imbalanced anaerobic
  conditions
• major contributors are hydrogen sulfide, volatile
  organic acids, and ammonia
• not formed under totally aerobic conditions
  (impossible to achieve with concentrated wastes)
• related to rapidly biodegradable waste components

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ODORS (2)

• less of a problem in high-solids wastes (gt25 TS)
• most effectively reduced by balanced anaerobic
  digestion
• hydrogen sulfide can be easily controlled and
  removed from biogas
• can also be managed using biofilters

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FACTORS INFLUENCING ECONOMICS

• highly site specific
• dependent upon several factors
• land and labor costs
• effluent discharge regulations
• energy prices
• herd size
• larger piggeries justify more complex treatment
  systems

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SUMMARY OF ECONOMIC STUDIES (1)

• Sweeten et al. (1981)
• construction costs, 22-36 per 68 kg hog
• 214-357 per m3 digester volume
• Chandler (1983)
• 1000 head, 89,000, 75kw covered lagoon
• paypack period was 3 years
• Yang (1995)
• treatment costs per year per head is 3.73 for
  herd of 300 3.01 for herd of 1000

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SUMMARY OF ECONOMIC STUDIES (2)

• Oleszkiewicz compared 12 systems for herds of
  gt10,000
• traditional systems using extended aeration,
  coagulation, lagoons, and land disposal were not
  cost effective
• cost effective systems used high-rate anaerobic
  and aerobic operations (1/3 to 1/2 cost of
  traditional systems)
• anaerobic treatment used for secondary treatment,
  treatment of sludges, and denitrification
• aerobic treatment was used to polish digester
  effluent and biological nutrient removal

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DEMOGRAPHIC TRENDS THAT WILL INFLUENCE SWINE
WASTE MANAGEMENT

• increase in human population
• increase in worldwide swine consumption
• increase in swine consumption in developing
  countries
• decrease in swine consumption in developed
  countries
• centralization of swine production
• stricter environmental regulations
• stricter public and animal health regulations

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FUTURE TRENDS IN SWINE WASTE MANAGEMENT
(developed countries)

• piggeries will be treated like other point-source
  industries
• wastes will be rapidly removed from source and
  treated to prevent harm to animals and workers
• wastes will be treated much like human wastes
  with solids separation, organic removal, nutrient
  removal, and disinfection

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FUTURE TRENDS IN SWINE WASTE MANAGEMENT
(developing countries)

• piggeries will be smaller (except those involved
  in export)
• pollution control will be slower
• high level of treatment will coincide with high
  level treatment of human wastes

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TRENDS THAT MAY LEAD TO SUSTAINABLE SWINE WASTE
MANAGEMENT

• anaerobic treatment because of less sludge and
  odors
• high-solids systems may to reduce water
  management problems
• location of piggeries in the vicinity of feed
  production to facilitate cycling of nutrients
• life cycle assessment for selection of waste
  management systems

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LIFE CYCLE ASSESSMENT OF WASTE MANAGEMENT

• feed production and processing
• waste collection and storage
• waste transport
• air emissions
• water emissions, net energy consumption
• fate of solids (e.g. use as compost)

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INTEGRATED WASTE TREATMENT SYSTEM (Standardized
Taiwan Design)

• mechanical bar screen
• aerated grit chamber
• solid/liquid separator
• composting
• preliminary settling
• sludge drying bed
• control system
• primary settling

• anaerobic digesters (RMP)
• equalization basin
• aeration tank
• sedimentation
• 2 sludge thickeners
• 2 sludge drying beds
• belt filter press