Production of Nitric Acid

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Production of Nitric Acid Environmental Impact
Assessment
Erik Tolonen
Nick Poulin
Environmental Engineering Environmental Planning
and Decision Making ENVE4104
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Contents
Introduction Risk Assessment Fault Tree Event Tree
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Introduction

• Chemicals of Interest
• Ammonia (NH3)
• Nitric Acid (HNO3)
• Nitric Oxide (NO)
• Nitrogen Dioxide (NO2)
• Nitrous Oxide (N2O)

Ammonia was determined to be the most hazardous
chemical present in the process
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Hazard Identification
All chemicals are non-carcinogenic
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Hazard IdentificationNH3
Ammonia is considered to be toxic by the Canadian
Environmental Protection Act

• Human Health Effects
• Causes irritation of the eyes, skin and
  respiratory system
• No Observed Adverse Effect Level (NOAEL) 6.4
  mg/m3
• Lowest Observed Adverse Effect Level (LOAEL)
  17.4 mg/m3
• Respiratory lesions increase the severity of
  pneumonia and rhinitis
• Environmental Effects
• Impact on certain types of plants and trees
  (reduced ability to retain water)

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Exposure Assessment
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Transport Media
Transport Mechanism
Exposure Mechanism
Population at Risk
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Air Transport Model
Assumptions - Transport by advection and
dispersion only - Ammonia is released from a 20 m
height stack with a 10 m plumb rise - Wind
direction is directly towards the city (Worst
Case Scenario) - No density or buoyancy effects
Gaussian Model Parameters - Atmosphere Stability
Class D - Rate of Emission 0.062 kg/s (223.2
kg/hr) over 30 hours - Total Amount of Ammonia
Released 6696 kg - Inhalation Reference Exposure
Level 0.3 ppm
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City
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Air Transport Model
Results - Ammonia levels in the city will reach
0.3 ppm when emission rate reaches 80311.7 kg/s
(80.3 tonnes/s). - Amount required is much
greater then current release at plant
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Water/Ground Water Transport Model
Assumptions -Transport by advection
only -Thoroughly mixed with river water -No
retardation or attenuation present in soil
Advection -Flow time to reach city 84.3
yrs -Flow time to reach river 28.2 yrs

• Solubility
• 42.8 wt at 0 OC
• - Amount of Ammonia entering groundwater
  insignificant

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Exposure Assessment

• Intake Dose
• I CxCRxEFxED/BWxAT
• C Conc. at exposure point 0.00008 ppm
  (0.00011mg/m3)
• CR Contact Rate 289.5 m3/hr 6947 m3/day
• EF Exposure Frequency 1.25 days/year
• ED Exposure Duration 30 hrs 0.003 year
• BW Body Weight 70 kg
• AT 1.25 days
• I 0.00003 mg/kg-day

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Toxicity Assessment

• Case Studies
• (1) Soda Ash Facility Workers Exposed to Ammonia
• No Observed Adverse Effect Level (NOAEL) 9.2
  ppm (6.4 mg/m3)
• (2) 344 Rats Exposed to Ammonia
• Lowest Observed Adverse Effect Level (LOAEL)
  17.4 mg/m3

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Risk Characterization

• Hazard Index for Ammonia
• HI CDI/RfC
• CDI chronic daily intake
• RfC reference dose 0.3 ppm

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Fault Tree
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Event Tree
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Conclusions

• Conclusions