Post on 28-Mar-2015
AIR
The Clean Air Act and Controlling Air Pollution
History of Legislation
• Original CAA of 1955 predates the EPA by 15 years
• It authorized technical and financial assistance to states
• Amendments were made in the 60’s, in 1970, 1977, and most recently in 1990
1960’s Amendments
• Amendments in the 60’s granted federal authority over vehicle emissions
• In 1970 requirements for national standards of ambient air quality were established NAAQS – w/ separate standards for new cars & stationary sources
1970 Amendments
• In 1970 air toxics were added as a new category of pollutants not covered under the original standards
• The National Emissions Standards for Hazardous Air Pollutants or NESHAP
• Substances included arsenic, asbestos, benzene, beryllium, mercury, radionuclides, radon 222, and vinyl chloride
State Requirements – 1970, Title I
• States were required to draw up state implementation plans – SIPs
• SIPs or State Implementation Plans are a collection of regulations a state will put into place to achieve the goals of the CAA
• These detail how ambient air standards would be met in each “air quality control region”
• The plan must include an inventory of all present sources and operating standards for all new development
• The EPA oversees the individual states’ plans and will take over enforcement if the state’s plan is unacceptable
1977 & 1990 Amendments
• The 1977 amendment stated that new facilities could be built in an area that was not meeting standards if existing sources could reduce their pollution
• The original act was just 50 pages long
• The 1990 amendments are close to 800 pages!
• The 1990 amendments addressed new issues such as acid rain emissions and moves to preserve the stratospheric ozone layer
• It established a system of tradable emission credits
Criteria Air Pollutants
• Primary standards – maximum ambient concentrations for the protection of the public health
• Secondary standards – levels acceptable to protect the public welfare
Nonattainment
• Not meeting the EPA’s primary standards
• 90 million Americans, 35% of the population live in nonattainment areas (mostly in urban areas)
Levels of Nonattainment
• Range from marginal to extreme
• Set for each of the criteria air pollutants
• The EPA tailors cleanup plans to the severity of the problem and sets goals that must be met or even stricter requirements will be enforced
Offsets
• When a company wants to expand
• The effect of new pollution sources must be offset by reductions elsewhere within the company or somewhere in the nonattainment area
Title IIMobile Sources
• Cars produce 60-80% less pollution than they did in the 1960’s
• However, automobiles still release over half of the smog-forming VOC’s and nitrogen oxides
• Motor vehicles emit 90% of the CO found in urban air
More Cars on the Road
• In 1970 Americans traveled 1 trillion miles
• Today we drive 4 trillion miles a year
• Public transportation and car pooling have not been embraced by the general population
• Removing lead from gasoline actually increased the amount of VOC’s released
• Pollution control devices, added to cars in 1970, were only designed to function for 50,000 miles
New Solutions in 1990
• Cleaner fuels
• Auto inspection requirements
• Removing sulfur from diesel fuel
• Reformulated fuels with less VOC’s such as benzene
• Oxygenated fuels in cold areas to aid in more complete combustion
• Detergents in gasoline prevents build-up of engine deposits which hamper efficient operation
• Development of alternative fuel sources such as alcohol, liquefied petroleum gas and natural gas
• Vapor recovery nozzles at gas stations
Title IIIAir toxics or hazardous pollutants• Benzene is released by motor vehicles
• Area emitter - Many small stationary sources include gas stations, paint shops and dry cleaners
• Major emitter - Chemical factories and coal-burning power plants are considered large stationary sources
Title IVAcid Rain
• Coal burning power plants in the Midwest and the Northeast are the primary source
• Coal from these regions has a much higher sulfur content
• Under Title IV, plants must have continuous emissions monitoring systems
• A system of emission allowances has been imposed
• These allowances can be traded or sold nationwide
• Bonus allowances are given to companies installing clean coal technology or using renewable energy sources
Title VPermit Program
• Permits are required by all major sources of air pollution and some smaller polluters, both for operating plants & new plants
• They include information on the type of pollutants emitted, how they’re controlled and how they will be monitored
• The EPA has the authority to fine violators
Title VIStratospheric Ozone
• 1978 – propellants in aerosol can were banned
• 1990 – schedule set for the phasing out of ozone-destroying chemicals
• The EPA has issued allowances for these substances in the mean time
• Recycling and labeling of these materials is required
• Service and maintenance of car air conditioners is strictly regulated
• New substitute products are being tested before being put into use
Title VII
• Covers enforcement provisions
Title VIII - IX
• Miscellaneous topics
• Greenhouse gases
• International issues
• Disadvantaged business concerns
End Legislation/Begin Sampling & Remediation Techniques
Sampling and Analysis of Emissions
• Ambient monitoring data allows us to see trends in air quality over time
• Provides baseline information
• Helps in developing computer models
• Help predict potential episodes
• Source emissions data is used to evaluate compliance
• Determines whether equipment is efficient and effective
• Hazardous pollutants are monitored at their source under the provisions of the NESHAPs standards
Monitoring Process
• Two parts – sampling and data management
• Sampling methods depend on the pollutant, its physical state and its expected concentration
• Concentrations are measured in mass per unit volume, usually micrograms per cubic meter or ug/m3
Calibration
• Checking and adjusting of instruments to insure quality control
• Comparing readings with a known standard
Quality Assurance
• Specific guidelines for analysis, calibration and calculation are listed as appendices of CFR 40 Part 50
• The EPA publishes a three volume Quality Assurance Handbook
• Agencies are required to provide a daily air quality index report in all urban areas with at least 500,000 people
The Gravimetric Approach
• Manual method used to measure particulate matter
• High volume method - catches material in a filter as it is drawn in by a blower
• The filter is weighed before and after
• Lead is collected in a similar fashion
• But must be separated from other particulates by dissolving it from the other particulates using acid
• The lead content of the solution is determined using an atomic absorption spectrometer
Carbon Monoxide Measurement
• An automated method involving a infrared spectrometric principle
• CO absorbs infrared radiation at characteristic wavelengths
• A sealed reference cell is compared to a sample cell through which the air passes
• When CO is present, it absorbs the radiation and the change is detected electronically
Ozone
• An automated method which involves gas phase chemiluminescence, chemical reactions that produce light
• Air is drawn through a tube containing ethylene which reacts with ozone emitting light that can be detected by a photomultiplier tube
Nitrogen oxide
• Detected in the same way as ozone
• But a different gas, ozone is used to create the reaction
Where Samples are Taken
• Is not specified in the Federal Reference Methods
• Downwind – upwind
• Proximity to trees, buildings and roadways
New Sources
• Where construction begins after the EPA publishes standards in the Federal Register
• The New Source Performance Standards, or NSPS, apply to specific sources
• The type of pollutants to be monitored, the allowable concentrations, kinds of monitoring required and the reference method used
Isokinetic Sampling
• Velocity of the gas at the sampling probe nozzle is the same as the velocity of the gas stream in the stack
Grab Technique
• Measures the volume of a sample by taking it at only one location, during one short continuous period of time
Integrated Sampling
• Takes samples from different locations over an extended period of time that is not necessarily continuous
Continuous Sampling
• Measuring a sample continuously using a source emission monitor
Air Pollution Control Techniques
• Equipment, processes or actions to reduce air pollution
• In serious nonattainment areas the Best Available Control Technology, BACT, will be required
• The Maximum Achievable Control Technologies, MACT, are required for sources emitting hazardous pollutants
Process Change
• Changing to low sulfur fuel
• Reformulated gasoline
• Alternative energy sources
• Housekeeping and maintenance
Emission Allowances
• An allowance is the limited authorization to emit one ton of SO2
• They can be traded or banked for future use
• Traded on the Chicago Board of Trade
• They are not a license to violate federal or state standards
• Companies without sufficient allowances are fined $2000 per ton for their excess emissions and will lose one allowance for each during the next year
• The bubble policy allow sources to be grouped to determine compliance
Control Equipment for Gaseous Emissions
• Adsorption
• Absorption
• Condensation
• Combustion
Adsorption
• Allowing the pollutant molecules to become attached to a solid surface like activated charcoal
• Can be regenerative or non-regenerative
Absorption
• Dissolving of a gaseous pollutant in a liquid solvent
• Spray towers, spray chambers, Venturi scrubbers and packed columns all maximize the opportunity for gas-liquid mixing
Condensation
• Gas or vapor is changed into a liquid by cooling or an increase in pressure
• Temperature reduction is the most cost effective
Combustion
• Combining a combustible material with oxygen producing heat and light
• Equipment includes flares, thermal incinerators and catalytic incinerators
Removing Particulates
• Efficiency of devices is calculated by taking the difference in the weight of particles in the air before and after, divided by the weight of particles when entering
• Control devices include settling chambers, cyclones, wet scrubbers, electrostatic precipitators, and fabric filters installed in a bag-house