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New Nuclear Power and Climate Change: Issues and Opportunities. Student Presentation Ashish K Sahu and Sarina J. Ergas University of Massachusetts - Amherst. Perchlorate Reduction in a Packed Bed Bioreactor Using Elemental Sulfur. Ashish K Sahu and Sarina J. Ergas. Background.
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New Nuclear Power and Climate Change: Issues and Opportunities Student Presentation Ashish K Sahu and Sarina J. Ergas University of Massachusetts - Amherst
Perchlorate Reduction in a Packed Bed Bioreactor Using Elemental Sulfur Ashish K Sahu and Sarina J. Ergas
Background • Perchlorate (ClO4-) • Stable • Non reactive • Trace levels of Perchlorate • Disruption of hormone uptake in thyroid glands
Geographic Contamination • No National Standards • MCL set by the Commonwealth of Massachusetts (2 mg/L) • California advisory levels (6 mg/L) • Other states (NY, NV, AZ, CO, TX) 18 mg/L Ref: ewg.org
Sources of Perchlorate • Natural • Atmospheric Sources • Chilean nitrate fertilizer • Anthropogenic • Missiles, Rockets • Fireworks • Leather Tannery Industries • Fertilizers
Treatment Processes • Physical Processes • Chemical Processes • Biological Processes • Combination of the above
Perchlorate Treatment Processes Physical Destructive Process Hybrid Technologies Chemical Biological GAC Bioreactors Others RO/NF CC-ISEP Phytoremediation Reducing metals IX Electrodialysis Others (MBR) CSTR PFR Bio-remediation
Outline • Biological Perchlorate Reduction • Use of Elemental Sulfur • Experimental Protocol • Results • Conclusions
Heterotrophic microorganisms Use organic carbon as their carbon source Electron donors are methanol, lactate, ethanol, wastewater Autotrophic microorganisms Use inorganic carbon as their carbon source eg: NaHCO3 Electron donors are S, Fe0, H2 Biological Perchlorate ReductionPrinciple: Microorganisms convert perchlorate to chloride
Use of Elemental Sulfur 2.87 S + 3.32 H2O + ClO4- + 1.85 CO2 + 0.46 HCO3- + 0.46 NH4+→ 5.69 H+ + 2.87 SO42- + Cl- + 0.462 C5H7O2N • Electron Donor: Elemental Sulfur • Electron Acceptor: Perchlorate • Carbon Source: Bi-carbonate • Low biomass production • Low nutrient requirements • Anoxic conditions • Alkalinity destroyed
Advantages of Elemental Sulfur • Waste byproduct of oil refineries • Excellent packing media • Relatively inexpensive and easily available • Applications in packed bed reactors and permeable reactive barriers
Objectives • Enrich a culture of Sulfur Utilizing Perchlorate Reducing Bacteria (SUPeRB) • Investigate the use of packed bed bioreactors to treat perchlorate contaminated waters by SUPeRB • Test the bioreactor for varying operating conditions
Batch Culture Enrichments • Denitrification zone of Berkshire wastewater treatment plant, Lanesboro, MA • 5mg/L ClO4-, So and oyster shell, nutrients in groundwater • Analytical Techniques • pH • ClO4- concentration using IC (EPA method 314.0)
Packed Bed Reactor • Reactor inoculated with SUPeRB • Media: Elemental Sulfur pellets (4 mm), oyster shell (3:1 v/v) • Volume: 1 liter • Ports: 5 ports
Bioreactor Performance-Phase II(Effect of Empty Bed Contact Time (hrs))
Bioreactor Performance-Phase II(Effect of Empty Bed Contact Time)
Bioreactor Performance-Phase II(Effect of sulfur size particles)
Bioreactor Performance-Phase II(Effect of Nitrate on Perchlorate Removal)
Summary • SUPeRB reduced ClO4- from 5 mg/L to <0.5 mg/L in 15 days using S0 and OS • High levels of perchlorate (5-8 mg/L) were successfully reduced to < 0.5 mg/L in the bioreactor at an EBCT of 13 hours • Low levels of perchlorate (80-120 mg/L) were reduced to < 4 mg/L at an EBCT of 8 hours
Summary… • Presence of nitrate did not inhibit perchlorate reduction • Perchlorate reduction was somewhat independent of media particle size
Applications and Future Work • Pilot scale of system for perchlorate remediation • Ex-situ remediation • In-situ remediation by Permeable Reactive Barriers (PRBs)
Acknowledgements • Water Resources Research Center (WRRC), TEI at UMass-Amherst • Massachusetts Technology Transfer Center (MTTC) for commercial potential • Advisor: Dr. Sarina Ergas • Teresa Conneely, Department of Microbiology for FISH and microbiology analysis • Tach Chu and Charlie Moe (High School) for culture and bioreactor maintenance
Thank you for your kind attention Email: aksahu@acad.umass.edu SUPeRB is SUPERB!!!