Phosphorous Recovery From Sewage Sludge Using Aqua Critox Super Critical Water Oxidation

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This presentation describes how the Aquacritox process can be used to generate renewable energy from wastewater sludge and enable phosphorus recovery. The Aquacritox supercritical water oxidation proces leads to complete sludge destruction. The presentation was presented at the European Biosolids Conference

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Phosphorous Recovery From Sewage Sludge Using Aqua Critox Super Critical Water Oxidation

  1. 1. <ul><li>Phosphorus recovery from sewage sludge using the Aqua Critox® supercritical water oxidation process </li></ul>
  2. 2. <ul><li>Phosphorous is a non renewable limited resource. </li></ul>
  3. 3. Estimates of Timeline for Peak in Phosphorus Production
  4. 4. Quantity of Phosphorous in sewage <ul><li>1.2 kg of Phosphorous per person per year </li></ul><ul><li>72,000 tonnes per year of Phosphorous across the UK. </li></ul><ul><li>Equivalent to 336,000 tonnes of P2O5 each year. </li></ul>
  5. 5. Value of Phosphorous in sewage <ul><li>Phosphate Rock offers a realistic bench mark for the market value of phosphorous. </li></ul><ul><li>336,000 tonnes of P 2 O 5 equates to 1.68 million tonnes of phosphate rock. </li></ul>
  6. 6. Value of Phosphorous in sludge
  7. 7. <ul><ul><li>At a value of $100 per tonne phosphate rock, the unrefined phosphorous in sewage sludge at 20% P 2 O 5 in the UK has a value of: </li></ul></ul><ul><li>$168,000,000 . </li></ul>
  8. 8. <ul><li>The value is linked to: </li></ul><ul><li>market demand </li></ul><ul><li>Cost of energy </li></ul>
  9. 9. Aqua Critox® <ul><li>This paper examines how the Aqua Critox® sludge to energy process can be used in combination with Biological phosphorus removal & a fluidised bed phosphorus recovery process to recover 70% of the total influent phosphorus load to the treatment plant. </li></ul><ul><li>The paper provides a simulated case study at a 500,000 PE Biological phosphorous removal plant illustrating how this can be implemented . </li></ul>
  10. 10. sludge is reduced to inert solid residue
  11. 11. Aqua Critox ® SEPARATOR BOILER WATER FEED PUMP STEAM SLUDGE FEED COOLER PRESSURE REDUCTION REACTOR HIGH PRESSURE PUMP HEATER ECONOMISER OXYGEN CO 2 ,N 2 ,0 2 Treated sludge STEAM GENERATOR GRINDER PUMP THICKENER CLEAN WATER RECYCLING PROCESS INERT RESIDUE Coagulant Phosphate
  12. 12. <ul><li>Two scenarios are examined. </li></ul><ul><li>The first is Biological phosphorus removal with anaerobic digestion, followed by sludge dewatering and sludge haulage off-site. </li></ul><ul><li>The second is the same Biological phosphorus removal plant, but with an Aqua Critox ® system in place of the Anaerobic digestion and sludge dewatering system. </li></ul><ul><li>Typical values for influent phosphorus loading have been used and a phosphorus removal efficiency of 85% is assumed. </li></ul><ul><li>Influent Parameters: </li></ul><ul><li>Flow: 125,000m 3 /day </li></ul><ul><li>Raw Influent Phosphorus Concentration: 6mg/l </li></ul><ul><li>Final Effluent Phosphorus Concentration: <1mg/l </li></ul>
  13. 13. Scenario A: P Mass Balance – Bio-P with AD (500K PE ) 1,125 kg/d DAFT Bio P Removal Secondary Clarifiers Filters Primary Clarifiers UV Digesters Centrifuge 112 kg/d Treated Wastewater 1,013 kg/d 750 kg/d 638 kg/d Waste Sludge 375 kg/d – Return P Load
  14. 14. Scenario B: Mass balance – Bio P with Aqua Critox® (500K PE) 530kg/d Recovered P from the recovery step. DAFT Bio P Removal Secondary Clarifiers Filters Primary Clarifiers UV Aquacritox Ash 805 kg/d 115 kg/d Treated Wastewater 690 kg/d 750 kg/d 585 kg/d 55 kg/d – Return P Load Supernatant 105 kg/d
  15. 15. Aqua Critox ® <ul><li>Recovered Phosphorous can be sold directly into the phosphate industry thus breaking the dependence on agriculture as a customer/ disposal route. </li></ul><ul><li>Recovered phosphorous can be utilised as a fertiliser if so required. </li></ul>
  16. 16. Aqua Critox ® <ul><li>530Kg of P </li></ul><ul><li>Recovered </li></ul><ul><li>1,992kg of slow release fertiliser . </li></ul>
  17. 17. Aqua Critox ® <ul><li>A sustainable approach to handling sludge </li></ul><ul><li>No hazardous by products </li></ul><ul><li>Net generator of renewable electricity </li></ul><ul><li>Very significant carbon foot print reduction </li></ul><ul><li>Recovery of Phosphorous </li></ul>
  18. 18. For more information <ul><li>Contact </li></ul><ul><li>John O’Regan [email_address] </li></ul><ul><li>Tel: +353 21 4928900 </li></ul>

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