Maximizing Environmental Risk Assessment in Chemical Processes

1. Chapter 11 Environmental Performance of a Flowsheet

2. Tier 3 Metrics How to combine • emissions estimation, • environmental fate and transport information, and • environmental impact data to obtain an assessment of the potential risk posed by releases from a chemical process?

3. Indexing Methods • Abiotic impacts: global warming; stratospheric ozone depletion; acidification; eutrification; smog formation. • Biotic impacts: human health; plant, animal and other organism health. • Environmental and economic sustainability issues: resource depletion.

4. global local regional

5. Environmental Risk Index

6. Global Warming Potential It is defined as the cumulative infrared energy capture from the release of 1kg of a greenhouse gas relative to that from 1 kg of carbon dioxide.

8. GWP for the Entire Process The equivalent process emissions of greenhouse chemicals in the form of the benchmark compound, CO2.

9. Indirect Global Warming Effects Organic chemicals of fossil-fuel origin will have an indirect global warming effect because of the CO2 released upon oxidization within the atmosphere and within other compartments of the environment. Organic chemicals whose origin is in renewable biomass (plant materials) have no global warming impact because the CO2 released upon environmental oxidization of these compounds is, in principle, recycled into biomass within the natural carbon cycle.

10. Indirect GWP To account for indirect GW effect for organic compounds with atmospheric reaction residence time less than ½ year,

12. Solution

13. Ozone Depletion Potential The ODP of a chemical is the predicted time- and height-integrated change in stratospheric ozone caused by the release of a specific quantity of the chemical relative to that caused by the same quantity of a benchmark compound, trichlorofluoromethane (CFC-11, CCl3F), i.e.,

15. ODP for the Entire Process

16. Acid Rain Potential The potential for acidification for any compound is related to the number of moles of H+ created per mole of the compound emitted.

17. Acid Rain Potential

19. Incremental Reactivity It is define as the change in moles of ozone formed as a result of emission into an air shed of one mole (on a carbon atom basis) of VOC. In general, predicted VOC incremental reactivities are greatest when NOx levels are high relative to reactive organic gases (ROG).

20. Smog Formation Potential

25. Solution • A commercial process simulator HYSYS was used to generate M&E balances and to calculate VOC emission rate from absorber. • VOC emission rates from distillation column, storage tank and fugitive sources were calculated with EPA emission factors and correlations from Environmental Fate and Risk Assessment Tool, i.e., EFRAT (see appendix F). • CO2, CO, TOC, NOx and SOx emission rates were also calculated within EFRAT based on energy requirements and an assumed fuel type, i.e., fuel oil no. 4.

26. decrease increase unchanged

27. 99.5% 50

28. 50

30. 50

31. Non-Carcinogenic Toxicity

32. Non-Carcinogenic Toxicity

33. Non-Carcinogenic Toxicity Indices for the Entire Process

34. Carcinogenic Toxicity

35. Carcinogenic Toxicity

36. Carcinogenic Toxicity Indices for the Entire Process

37. Weight of Evidence (WOE) • Lists of SF values can be found in • US EPA, Health Effects Assessment Summary Tables (HEAST), 1994. • US EPA, Integrated Risk Information System (IRIS), 1997. • If SF is not available, WOE classifications have been tabulated for many industrial chemicals by consideration of evidence by a panel of experts. • The definitions of each WOE classification is sown in Table 11.3-3 along with a numerical hazard value (HV). • The HV values can be used to replace SF in the above equations for carcinogenic potentials.