Questions and Answers
What are the three general options in air emissions abatement?
Waste minimization, Recovery and recycling, Destruction or disposal
Which properties are important to characterize a stream for equipment selection in air emissions abatement?
Electrostatic precipitators are used to remove liquid particles from a gas stream.
False
A filter comprises a solid porous media which allows only gas and very small particles to pass through it. Gas filters normally consist of either bags or cartridges through which the gas passes. The performance of a filter is characterized by two parameters: ______ and Pressure drop.
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What percentage of the world's FGD systems are non-regenerable?
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Which of the following are considered pollutants from agriculture?
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Controlling agricultural pollution requires an interdisciplinary approach.
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What are the two major oxides implied by the term NOx?
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What is the purpose of a site investigation for animal waste lagoons?
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What type of soils pose special challenges for a safe design of agricultural facilities?
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What is the underlying purpose of agricultural point source pollution control facilities?
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The design capacities of agricultural point source pollution control facilities are determined by the rate at which the pollutants are generated and the required ______________________ period.
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The characteristics of agricultural wastes are similar to those of wastewater treatment facilities.
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What is the primary objective of agricultural non-point source pollution control practices?
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What is the most economical, practical, and environmentally sustainable method for managing agricultural wastes?
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The rate of application of organic wastes to land is dependent on the ______________________ assimilative capacity of the soil system.
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What is the primary factor that determines the long-term assimilative capacity of a waste application site?
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What is the primary consideration for designing land application systems?
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What is the difference between organic and inorganic compounds?
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Classify the following compounds as either organic, inorganic, or particulate: Dry cleaning agents, Petrol, Ammonia, Boiler flue gases.
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Under what circumstances should incineration be considered as a method of air emissions control?
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Why would urea be preferable to ammonia as a method of controlling NOx emissions?
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Explain why sulphur and NOx are present and are harmful pollutants in industrial air emissions.
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Discuss the obstacles to agricultural pollution control.
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An activated sludge effluent treatment plant is experiencing complaints from surrounding area. Discuss the possible sources of odors and the ways to control them.
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Study Notes
Industrial Air Emissions Control
- Industrial air emissions are regulated to maintain air quality standards
- Various air emission abatement technologies are used to achieve these standards
- Waste stream characteristics include:
- Gaseous and particulate contaminants
- Density, particle size, and volatility
- Chemical and physical properties (e.g., solubility, adsorptive properties)
- Three general options for air emissions abatement:
- Waste minimization
- Recovery and recycling
- Destruction or disposal
Characterizing the Air Stream
- Wastewater treatment manipulates the chemistry of the liquid waste stream to purify it
- Air pollution control manipulates the physical, chemical, and biological properties of the gas stream
- Important measurable properties of the stream:
- Composition
- Flowrate
- Temperature
- Pressure
- Additional information required for equipment selection:
- Variability in stream characteristics
- Explosivity of the stream
- Corrosiveness of the stream
Equipment Selection
- Equipment selection depends on the type of compounds to be removed:
- VOCs (defined as organic substances with potential to cause environmental effects)
- Inorganic compounds
- Particulate matter
- Major types of equipment used:
- Incinerators
- Adsorbers
- Condensers
- Filters
- Scrubbers
- Absorbers
- Particle collection devices
Equipment Design
- Condensation:
- Transfers heat from a vapor stream to a cooling stream
- Can be direct or indirect contact type
- Shell and tube design is commonly used
- Absorption:
- Selectively absorbs compounds from a gas stream
- Generates a liquid waste stream
- Adsorption:
- Used to recover compounds from dilute streams
- Can be used in various ways (e.g., fluidizing, rotating, or fixed bed)
- Filtration:
- Uses a solid porous media to remove particles
- Gas filters typically consist of bags or cartridges
- Performance characterized by particle collection efficiency and pressure drop
Special Topics
- Flue gas desulphurization (FGD):
- Two main types: non-regenerable and regenerable
- Non-regenerable systems generate a residue that must be disposed of
- Regenerable systems convert sulphur dioxide to a marketable product
- NOx removal:
- Three main mechanisms of NOx production: reaction of N2 with oxygen, nitrogen existing in the fuel, and reactions of fuel-derived radicals with N2
- Effective control of NOx emissions requires knowledge of the dominant formation mechanism
Agricultural Pollution Control
- Primary objective of agricultural enterprise is to optimize profit
- Modifications to agricultural practices have increased pollution potential
- Need to control pollution from agriculture is more obvious, especially with regard to water pollution
- Obstacles to agricultural pollution control:
- Unique characteristics of the agricultural industry
- Non-homogeneous biological system (soil)
- Large land areas involved
- Unpredictable climatic events
- Low profit margins
- Agricultural pollution control principles:
- Interdisciplinary approach combining expertise of engineers, agronomists, soil scientists, and biologists
- Controlling pollutants such as nutrients, organic matter, pathogens, synthetic organic chemicals, and eroded soil
- Point and non-point sources of pollution
- Total quality management (TQM) approach or systems approach required for success### Point Sources of Agricultural Pollution
- Key sources of pollution in agricultural systems:
- Farmyard (uncovered exercise or feeding areas, soiled water storage tanks)
- Facilities for storing animal wastes (slurry pits and tanks, dungsteads)
- Facilities for collecting and storing silage effluent (pads and tanks)
- Facilities for storing and handling pesticides (storage sheds, filling and rinseate collection areas)
- These sources pose environmental threats due to concentrating large amounts of potential pollutants in a compact area
- Minimizing pollution risks depends on properly designing, constructing, and managing facilities
Designing and Managing Facilities
- Design principles:
- Contain pollutants and prevent uncontrolled release to the environment
- Provide adequate waste storage capacities
- Ensure structural integrity
- Consider site location and soil conditions
- Construction practices:
- Follow accepted engineering standards and procedures
- Select resistant construction materials
- Ensure proper supervision and inspection
- Government agencies provide design guidelines and specifications for facilities
Non-Point Sources of Agricultural Pollution
- Non-point sources of pollution:
- Land areas where agricultural production takes place
- Diffuse nature of pollution makes it difficult to identify precise origins
- Transportation agents:
- Precipitation excess and snowmelt (surface runoff and interflow)
- Wind (minor contribution)
- Drainage water through the soil profile (groundwater)
- Controlling non-point source pollution:
- Preventing pollutants from leaving the production system (soil)
- Keeping pollutants within the confines of the root zone and field edge
Point Source Controls
- Site selection:
- Locate facilities away from surface waters and down gradient from nearby groundwater wells
- Consider soil conditions (low organic matter, low shrink-swell potential, good compactability, etc.)
- Sizing of structural facilities:
- Determine design capacities based on pollutant generation rates and storage periods
- Consider biochemical principles for facilities with treatment capabilities
Non-Point Source (NPS) Controls
- Agricultural NPS pollution controls:
- Managerial, structural, or vegetative practices
- Objective: prevent or reduce the availability, release, or transport of pollutants to receiving waters
- Best Management Practices (BMPs):
- Most effective and practicable control techniques for specific farm characteristics and pollution problems
- Consider climate, soils, and topography
Land Application of Wastes
- Land application of wastes:
- Economical, practical, and environmentally sustainable method for managing agricultural wastes
- Recycles valuable nutrients and organic matter
- Design and management principles:
- Apply wastes at correct rates and times
- Use correct methodology
- Consider hydrologic and agronomic principles
- Limiting factors: hydraulic loading, organic loading, nutrient loading, or metal loadings
Codes of Practice for Land Application of Animal and Other Wastes
- Typical code of good practice:
- Apply wastes at rates that take account of crop nutrient requirements and soil fertility levels
- Use regular soil and slurry testing to determine nutrient needs and supplies
- Avoid applying wastes on wet or waterlogged soils, frozen or snow-covered soils, or areas near surface waters and groundwater wells
- Check weather forecasts before applying wastes
- Use calibrated application equipment and operate it according to specification
- Minimize odor emissions
Agricultural Air Pollution Control
-
Major air pollutants from agriculture:
- Odorous emissions related to storage and handling of animal wastes
-
Three main areas with which odors are associated:
- Housing/yard area
- Waste treatment/holding area
- Waste utilization area
-
Controlling odors:
- Practices associated with good animal husbandry
- Maintenance of mechanical apparatus for waste removal
- Ventilation and temperature control in buildings
- Keeping yards clean of animal wastes and spilled feeds
- Minimizing odor generation and dispersing odors at non-objectionable levels### Air Emissions Control
-
Incineration should be considered as a method of air emissions control under certain circumstances, such as avoiding spreading on weekends and holidays, and avoiding the use of application techniques that tend to atomize wastes or disperse them into the atmosphere.
Compounds Classification
- Organic compounds: petrol, dry cleaning agents
- Inorganic compounds: ammonia
- Particulate compounds: boiler flue gases
NOx Emissions Control
- Urea is preferable to ammonia as a method of controlling NOx emissions.
- Sulphur and NOx are present and are harmful pollutants in industrial air emissions because they can cause acid rain and respiratory problems.
Agricultural Pollution Control
- Obstacles to agricultural pollution control include:
- Incineration and its potential to spread pollutants on weekends and holidays
- Prevailing winds directing pollutants towards neighboring housing and population centers
- Application techniques that atomize wastes or disperse them into the atmosphere
Odor Control in Activated Sludge Effluent Treatment Plants
- Possible sources of odors in activated sludge effluent treatment plants:
- Wastewater treatment process
- Sludge handling and disposal
- Plant operations and maintenance
- Ways to control odors:
- Implementing odor control measures such as covering treatment units and using odor-reducing technologies
- Improving plant operations and maintenance practices
- Optimizing wastewater treatment processes
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Description
This quiz covers guidelines for minimizing environmental impact when applying waste, including proper equipment use, buffer zones, and odor emission minimization.