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Fate of Siloxanes: Precombustion removal vs. post combustion removal

Evaluating precombustion vs post-combustion removal of siloxanes, their release mechanisms, persistence, and oxidation risks. Analyzing cyclic volatile siloxanes in landfill and wastewater systems. Investigating multiphase partitioning and hazard potential. Assessing cost implications and adsorptive capacity of activated carbon gas samplers.

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Fate of Siloxanes: Precombustion removal vs. post combustion removal

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  1. Fate of Siloxanes: Precombustion removal vs. post combustion removal Sharon Surita, PhD Candidate Department of Civil &Environmental Engineering April 22, 2015

  2. Project Website https://siloxane.fiu.edu/

  3. Conferences • World Environmental & Water Resources Congress 2014 (EWRI 2014) - Emerging siloxanes and Environmental Implications in Wastewater Treatment Systems • Global Waste Management Symposium (GWMS 2014) - Concentration and comparison of siloxanes found in urban landfill • Odors and Air Pollutants 2014 Conference (WEF 2014) - Release and Partitioning of Siloxanes during Biosolids Decomposition in Anaerobic Digesters • Solid Waste Association of North America Florida Sunshine Chapter (SWANA 2014) - Contribution of siloxanes from WWTP to codisposallandfills • 8th Intercontinental Landfill Research Symposium (ICLRS 2014) - Emergence and Fate of Siloxanes in Landfills • World Environmental & Water Resources Congress 2015 (EWRI 2015) - Loading, persistence, and fate of siloxanes in wastewater treatment plants:  Levels in influent, effluent, biosolids, and digester gas

  4. Emergence of cyclic volatile siloxanes (D4 and D5) Objectives: Evaluate release mechanisms Estimate persistence times Projected release quantities

  5. Emergence of cyclic volatile siloxanes (D4 and D5) – cont.

  6. Characterization of deposits forming during combustion Objectives: Compare composition and morphological characteristics of ADG and LFG

  7. Characterization of deposits forming during combustion – cont. > 5C:7O:1Si Biogas from AD 2:3.5:1 LFG

  8. Oxidation and nanotoxicity Objectives: Estimate quantities of SiO2 formation and release during combustion Analyze exposure risks in relation to particle size, release rate and availability

  9. Oxidation and nanotoxicity – cont.

  10. Multiphase partitioning and hazard index in biosolids Objectives: Investigate release of siloxanes in aqueous, gas and biosolids. Estimate hazard potential based on partitioning and reaction rates

  11. Multiphase partitioning and hazard index in biosolids – cont.

  12. Multiphase partitioning and hazard index in biosolids – cont. Monitoring at South Dade Monitoring at South Dade Not significant removal of predominant siloxanes

  13. Multiphase partitioning and hazard index in biosolids – cont. Monitoring at South Dade

  14. Contribution of Siloxanes to COD loading Objectives: estimate the phase transfer (water, solids, gas), fate, and contribution to COD loading of selected siloxanes (D4, D5 and D6) in the wastewater systems.

  15. Contribution of Siloxanes to COD loading – cont.

  16. Contribution of Siloxanes to COD loading – cont.

  17. OBJECTIVES • Compare the economic feasibility of pre-combustion removal to post-combustion removal of siloxane deposits • Evaluate adsorptive capacity and suitability of activated carbon-type gas samplers for qualitative analysis

  18. Where are siloxanes used?

  19. Estimated Siloxane Removal

  20. Adsorption vs. manual maintenance

  21. Estimated annual maintenance costs for siloxane removal

  22. Equations to estimate installation costs of adsorption system

  23. Estimated capital cost of fixed-bed carbon adsorption system (FBCAS).

  24. Estimated capital costs of FBCAS in dollars per cubic foot of LFG utilized.

  25. Assumptions

  26. Comparison of costs

  27. Siloxane sampling methods

  28. SEM/EDS analysis

  29. Elemental Composition

  30. Manufacturer Specifications

  31. Activated carbon

  32. Landfill Gas Sampling Results

  33. Digester Gas Sampling Results

  34. Removal

  35. Questions?

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