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Different Post-treatments September 15, 2016 Funding provided by - - PowerPoint PPT Presentation
Different Post-treatments September 15, 2016 Funding provided by - - PowerPoint PPT Presentation
Transformations of Organic Carbon in three Greywater Recycling Systems employing Different Post-treatments September 15, 2016 Funding provided by The Bill and Melinda Chris Ziemba Gates Foundation Odile Lariv Eberhard Morgenroth Three
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5,9 l GAC
Post- Treatment Storage
Use Use Biologically- Activated Membrane Bioreactor (BAMBi) Storage Post- Treatment
Water recycling system overview
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Goals for Post-Treatment 1. Remove color 2. Prevent pathogen regrowth Transformations and removals of
- rganic carbon
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Non-selective Post-treatment Selective Post-treatment
Transformations and removals of
- rganic carbon
Goals for Post-Treatment 1. Remove color 2. Prevent pathogen regrowth
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Three Post-Treatments to test
Ozone Electrolysis GAC
Oxidation: Hydroxyl radical:
- 2.7 eV
- xidation potential
- lifetime in H20 < sec.
Non-Selective Oxidation: Ozone:
- 2.07 eV
- xidation potential
- lifetime in H20~20 min.
Selective for aromatics and double bonds Sorption/ Biodegradation: Selective for non-polar/ biodegradable compounds
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Experimental approach
Ozone Electrolysis GAC
Batch experiments with real permeate
- Targeting maximum carbon removal
- Monitor
DOC Color Liquid chromatography profiles (size) Assimilable Organic Carbon (AOC)
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DOC batch profile
Exposure Exposure Exposure
Energy (kWhr L-1) 0 0.4 0.8 1.2 0 0.2 0.4 0.6 Energy (kWhr L-1) Energy (kWhr L-1) 0 67 133 200 0 0.005 0.009 0.014 Times passed through GAC
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Color removal and DOC concentrations
Color Good enough Cannot see any color
Exposure
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AOC and DOC
AOC DOC
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Liquid Chromatography – Organic Carbon Detector
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Ozone – size chromatography
1 2 3 4 4 5
# indicated peak order ( # means size)
AOC generation may be linked to increases in Building Blocks, Low Mol.
- Wt. Humics and Neutrals
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Electrolysis – size chromatography
1 2 3 4 4 5
# indicated peak order ( # means size)
AOC production is not clearly linked to increases in LC-OCD fractions
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Biological stability through AOC
Biological stability AOC threshold
?
Exposure Exposure Exposure
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Combining color removal and biological stability
Exposure Exposure Exposure
Biological stability AOC threshold
?
Color Good enough Cannot see any color
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Conclusions
- Ozone, Electrolysis and GAC are able to remove color
- Only GAC is able to demonstrate reliable biological stability
by AOC measurement
- Ozone and Electrolysis may be able to achieve biological
stability through antimicrobial residual (ozone and chlorine)
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END
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Conclusions
- Ozone (more strongly) and Electrolysis demonstrate preferences for
removal of color relative to DOC, and target the humic substance fraction of the LC-OCD profile. GAC treatment is non-selective.
- Both Ozone and Electrolysis demonstrate AOC production at different
points in the batch DOC removal profile.
- The production of AOC by electrolysis may be linked to increases in
Building Blocks, Low Mol. Wt. Humics and Neutrals.
- Biological stability (by AOC) requires more treatment than color removal.
- Ozone may be able to achieve biological stability.
- Electrolysis failed to achieve biological stability.
- GAC is able to achieve biological stability.
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Experimental approach
Ozone Electrolysis GAC
- Boron-doped diamond
- 14 V 2.4 A
- 5 min. polarity reversal
(with 1 min. off)
- 0.7 L/min recirculation
- temperature controlled
- Corona-discharge
- zone generator
- 300 mg/hr at generator
- bubbled (2 L/min air)
- 3-4 mm ø bubbles
- 2 meter tall column
- Repeated pouring
through GAC column
- 1-1.4 mm grain size
- 0.3L GAC (170 dry g)
1 Batch experiments with real permeate
- Targeting maximum carbon mineralization / removal
- Monitor DOC, Color, Chromatography (size), Assimilable Organic Carbon
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Current Prototype uses Electrolysis
5,9 l GAC Mineralization of Carbon Production of Chloride
- H2O
HO*
+
B
+
B
+
H+ HO* RO+H+ R H+ H+ H2 H2 e- Cathode Anode e- R= organics B= Boron dopant HO*= hydroxyl rad
Oxidation potential 2.7 eV =
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Color loss by spectrophotometer
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Size exclusion chromatography
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Many System Iterations
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Liquid Chromatography – Organic Carbon Detector
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DOC Color DOC Color DOC Color
Summary
- Ozone produces delayed AOC increase
- Maybe linked to increases in specific LC-OCD fractions
- Electrolysis immediately produces AOC increase
- not clearly linked to a LC-OCD fraction
- GAC does not produce Ozone
Ozone Electrolysis GAC Removal preference Sufficient Color Removal YES YES YES Biological Stability (AOC) ??? NO YES
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5,9 l GAC
1250 mg/L TOC 45-50 mg/L TOC ~8 mg/L TOC 1212 mg/L TOC 1202 mg/L TOC ~2 mg/L TOC ~12 mg/L TOC ~18 mg/L TOC Activated Carbon Electrolysis No Post- treatment
Impacts on full-scale bioreactor operation
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