Production of Nitric Acid Environmental Impact Assessment Erik TolonenNick Poulin Environmental Engineering Environmental Planning and Decision Making ENVE4104

Contents Introduction Risk Assessment Fault Tree Event Tree

Introduction Chemicals of Interest Ammonia (NH 3 ) Nitric Acid (HNO 3 ) Nitric Oxide (NO) Nitrogen Dioxide (NO 2 ) Nitrous Oxide (N 2 O) Ammonia was determined to be the most hazardous chemical present in the process

Hazard Identification All chemicals are non-carcinogenic ChemicalRfCToxicity Score Ammonia0.3 ppm (IRIS) Nitric Acidn/a Nitric Oxide n/a Nitrogen Dioxide mg/m3 (NAAQS)n/a Nitrous Oxide n/a

Human Health Effects Causes irritation of the eyes, skin and respiratory system No Observed Adverse Effect Level (NOAEL) – 6.4 mg/m 3 Lowest Observed Adverse Effect Level (LOAEL) – 17.4 mg/m 3 –Respiratory lesions increase the severity of pneumonia and rhinitis Environmental Effects Impact on certain types of plants and trees (reduced ability to retain water) Hazard Identification NH 3 Ammonia is considered to be toxic by the Canadian Environmental Protection Act

Exposure Assessment Nitric Acid Plant Wind Rain Groundwater Ingestion, Absorption Inhalation NH 3

Release of Ammonia Air RiverGround Water Advection/Dispersion AdvectionAdvection/Dispersion Inhalation Ingestion, Absorption Transport Media Transport Mechanism Exposure Mechanism Adults/Children Population at Risk Ingestion, Absorption Adults

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: kg/s (223.2 kg/hr) over 30 hours - Total Amount of Ammonia Released: 6696 kg - Inhalation Reference Exposure Level: 0.3 ppm

City

Air Transport Model: Results: - Ammonia levels in the city will reach 0.3 ppm when emission rate reaches kg/s (80.3 tonnes/s). - Amount required is much greater then current release at plant

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: wt % at 0 O C - Amount of Ammonia entering groundwater insignificant

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

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

Risk Characterization Hazard Index for Ammonia HI = CDI/RfC CDI = chronic daily intake = RfC = reference dose = 0.3 ppm

Fault Tree Release of Ammonia to Environment AND Faulty equipment OR Excessive concentration of NH3 in process OR Broken pipes Loose pipe connections Insufficient oxidation of ammonia Excess ammonia inputted into system by plant operators OR Insufficient air supplied to ammonia converter Improper operating temperature or pressure OR Miscalculation of required ammonia Improperly calibrated measuring instruments Improper upkeep or maintenance by plant operators OR Loose connection at ammonia input port Improper upkeep or maintenance by plant operators Excess pressure within pipes

Event Tree Source Transport Media Transfer Mech Exposure Mech Receptors Exposure Route Nitric Acid Production Process Air -Critical Water Soil Washout by rain Volatilization Uptake by plants Ambient air Drinking water wells Consumption of food Anyone breathing the air Users of well water Humans, animals that eat the plants Inhalation Ingestion, Absorption Ingestion

Conclusions