integrated passive biological selenium treatment
TRANSCRIPT
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7th International WETPOL Symposium Big Sky, Montana, USA August 21-25, 2017
Integrated Passive Biological Selenium Treatment System: Results of a 1-year Pilot Study
August 2?, 2017
James S. Bays1
Chelsea Ransom1
Robert BT Thomas1
Sarah Foster1
Patrick Mulhern2
Luis Tovar2
1 CH2M
2 Cottonwood Water & Sanitation District
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Biological Treatment Converts Oxidized Se to Reduced Insoluble Forms
CH2MHILL 2012
Org-Se
(CH3) 2Se
SeO42-
SeO32-
Se0
HSe-1
• Organics + Selenite/Selenate + N + P -> New Cells + CO2 + H2O + Se0
• Order of reduction: DO → NO2- → NO3
- → SeO32- → SeO4
2- → ClO42- → SO4
2-
• Volatilization as outcome of organic selenium formation
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Passive Biological Treatment Systems Configured to Reduce Se and Remove “By-products”
Wood Chips & Compost
Peat Gravel
Rip-rap & Cobble
Aerobic Cascade Aeration
Aerobic Filter (APC)
BOD, S- Polishing
Vertical Downflow Biochemical Reactor (BCR)
NO3, SeO4 Reduction
Vertical Upflow Anaerobic Filter Se0 Particulate
Capture
Flow 409 m3/d [Se] in 12 µg/L HRT 1 day (BCR) CAPEX $765,000 OPEX $15,000/A
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Joint Water Purification Plant (2010) to Replace Non-renewable Deep Groundwater Supply
Joint Water Purification Plant
Reverse Osmosis
Microfiltration
Colorado USA Parker CO
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Despite Supply of Renewable Best Quality Water, JWPP Discharge Limited by Concentrate Se
Discharge to surface water
Permit Violation Discharge Exceeds Selenium Aquatic
Protection Standard (4.6 µg/l)
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Pilot System Train 1: BCR>SPC>PPC>AF>APC
Head Tank
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Pilot System Train 2: BCR>AF>APC>PPC
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Pilot System Recipe
Unit Media %
BCR Wood Chips 30
Field Hay 30
Horse Manure 5
Peat 5
Limestone Sand 5
Sawdust 25
VUF Peat 75
Sawdust 25
SPC ZVI 5
Sand 95
PPC T1: Siderite 100
T2: Bold&Gold 100
BCR
APC
Sample Port
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2016 Project Schedule Extended to Support Specialized Analysis
Activity J F M A M J J A S O N D J
Phase 1
Construction
Establishment
Optimization
Verification
Phase 2
Phase 3
Autopsy
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Redox Potential Confirmed Anaerobic Condition; BOD/COD Loss Defined Establishment Period
Redox Potential
BOD
COD
-150
-150
Optimization
Establishment
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Phase 1 Pilot: BTS Se Removal Capacity >90% and Can Achieve Se Removal Target
0
20
40
60
80
100
120
1-Feb 21-Feb 12-Mar 1-Apr 21-Apr 11-May 31-May 20-Jun 10-Jul
Tota
l Se
(µg
/L)
HT T1 T2 Table Value Standard
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Phase 2 Train 1 Pilot: No Significant Effect of Flow Variability on Se Removal
0
10
20
30
40
50
60
70
80
30-Aug 9-Sep 19-Sep 29-Sep 9-Oct 19-Oct 29-Oct
Sele
niu
m C
on
cen
trat
ion
(µ
g/L
)
Influent Train 1 Effluent Table Value Standard 30 day rolling average
75% flow 50% flow Variable flow
Baseline
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Phase 2 Train 2 Pilot: No Significant Effect of Operational Schedule on Se Removal
0
10
20
30
40
50
60
70
80
30-Aug 9-Sep 19-Sep 29-Sep 9-Oct 19-Oct 29-Oct
Sele
niu
m C
on
cen
trat
ion
(µ
g/L
)
2016
Influent Train 2 Effluent Table Value Standard 30 day rolling average
Baseline No weekend flow Weekend recirculation
Weekend recirculation with sodium nitrate
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Phase 3 Pilot: No Significant Effect of Flow Reduction on Removal But Some Se Re-oxidation By Aeration • Low Se in BTS
discharge
• Se release from polishing cells
0
5
10
15
20
25
30
35
40
45
50
12-Nov 19-Nov 26-Nov 3-Dec 10-Dec 17-Dec
Sele
niu
m (
µg
/L)
T2:HT T2:B (BCR2) T2:E (PPC Effluent) TVS
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Mass Distribution: Most Se Retained in Anaerobic Cells
0.1
1.0
10.0
100.0
1000.0
BC
R1
-To
p
BC
R1
-Mid
BC
R1
-Bo
t
SPC
-Bo
t
SPC
-Mid
SPC
-To
p
BC
R2
-Sca
le
BC
R2
-To
p
BC
R2
-Mid
BC
R2
-Bo
t
PP
C-B
ot
PP
C-M
id
PP
C-T
op
AP
C1
-To
p
AP
C1
-Bo
t
AP
C2
-To
p
AP
C2
-Bo
t
Effl
uen
t
Tota
l Se
(mg)
Train 1
0.1
1.0
10.0
100.0
1000.0
BC
R1
-To
p
BC
R1
-Mid
BC
R1
-Bo
t
BC
R2
-Bo
t
BC
R2
-Mid
BC
R2
-To
p
AP
C1
-Pe
at
AP
C1
-Ph
ase
1
AP
C1
-To
p
AP
C1
-Bo
t
AP
C2
-To
p
AP
C2
-Bo
t
PP
C-T
op
PP
C-B
ot
Effl
ue
nt
Tota
l Se
(mg)
Train 2
Anaerobic Aerobic Anaerobic Aerobic
Material Baseline Se
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Mass Balance Accounted for 78% (T1) and 87% (T2) of Total Applied Se
69.0% 75.8%
8.8%
10.0%
22.0% 13.3%
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
T1 T2
Perc
enta
ge o
f To
tal S
e A
pp
lied
Anaerobic Aerobic Effluent Residual
Residual: Volatilization Aggregate Error
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Se Speciation Confirmed Reducing Conditions and Long-term Storage in Anaerobic Process Units
0
1
2
3
4
5
6
7
8
9
Se (
mg
/kg
ww
)
Train 1
0
1
2
3
4
5
6
7
8
Se (
mg
/kg
ww
)
Train 2 Salt
Adsorbed
AmorphousCrystallineSelenide
Residual
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60% Design: 1.9-ha Biological Treatment System to Treat and Polish 3.6 MLD RO Concentrate
JWPP
System Cells Area (m2)
Media Depth
(m) Downflow
Biochemical Reactor
6 10118 2.1
Anaerobic Upflow Filter
3 1295 2.3
Media Polishing Cell
2 648 2.2
Aerobic Polishing Cell
2 6475 1.3
BCR AF MPC
APC
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Conclusions, Applications and Next Steps
• Se treatable to target by passive biological system
• Other constituents are treatable to standards
• Spent media not toxic
• 20 yr media life
• Treatment train 2 adopted
• Will achieve net reduction of Se in watershed
• Revising costs
• Construction 2018
Discharge to surface water
Integrated Passive Biological Selenium Treatment System: Results of a 1-year Pilot Study
James S. Bays
Grateful acknowledgement to Cottonwood Water & Sanitation District
Thanks to project team: Chelsea Ransom, Robert BT Thomas, Sarah Foster, Patrick Mulhern, Luis Tovar, Jason Rysavy
7th International WETPOL Symposium
Big Sky MT USA August 23 2017
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Calcium - Passive Precipitation Chloride – Conservative, No Removal
Calcium Chloride
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Phosphorus Removed in Aerobic Polishing Cells; Co-precipitation with CaCO3
[P]in = 0.78 mg/L Train 1: 96% 0.03 mg/L Train 2: 83% 0.13 mg/L
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All Metals Removed to BDL by Sulfide Precipitation, Sorption, Hydroxide Formation: Copper Example
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Iron Cycled Based on Internal Sources, Redox Potential and Oxygen Supply
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Active Biological Treatment Supplies Carbon, Nutrients to Fixed or Fluidized Media Beds
test
Fluidized Bed Reactor West Virginia USA Coal Mine Drainage
Flow 11,335 m3/d [Se] in 45 µg/L HRT 15 minutes CAPEX $49 MM OPEX $3.5 MM/A
ABMet Process