OnSite Sodium Hypochlorite Generation from Desalination Concentrate

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On-Site Sodium Hypochlorite Generation from
Desalination Concentrate

• Leonard W. Casson1, William W. Edgar2, Gary
  Hunter3
• 1University of Pittsburgh, Pittsburgh, PA
• 2FUSE, Inc., Brooksville, FL
• 3 Black and Veatch, Kansas City, MO

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Application/Opportunities

• Ongoing Hypochlorite Ash-Leachate Optimization
  Studies and Full-Scale Implementation (Ogden
  Martin Waste to Energy Facility, Pasco County,
  Florida)
• Sodium Hypochlorite Generation From Desalination
  Concentrate, Membrane Concentrates or other High
  Salt Concentrate Solutions and
• Sodium Hypochlorite Generation From Ion Exchange
  Backwash.

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Previous On-Site Generation WorkbyThe FUSE Team
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Problem Statement

• Pasco County, Florida is permitted for six
  ten-acre lined ash monofil cells.
• Presently, ash is in two ten-acre cells.
• Rainfall entering these cells generates leachate
  which must be treated and disposed of to the
  satisfaction of the Florida Department of
  Environmental Protection.

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Problem Statement(Continued)

• Problems existed with the current Leachate
  Management Facility (capacity 35,000 gpd).
• These problems, combined with unusually high
  rainfall in 1997 and 1998 (41.6 inches from
  December, 1997 through March, 1998), resulted in
  excess leachate collection in the ash cells
  (approximately 37 million gallons).

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Ash Monofil Cells, March 1997
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Overall Objective

• The objective of this initial pilot-scale study
  was to investigate the feasibility of generating
  liquid sodium hypochlorite landfill ash leachate.

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Why ???

• The sodium hypochlorite generated from ash
  leachate may be used to disinfect wastewater
  treatment plant effluent and then perhaps enter a
  water reclamation/reuse system.

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Raw Leachate Characterization
Specific Conductivity
Chloride
TDS
Sodium
Sulfate
Potassium
Sampling Location
(mg/L)
(mg/L)
(mg/L)
(mg/L)
(mg/L)
(umhos)
Raw
28,072
64,100
5,120
429
3,300
57,200
Raw
29,110
98,500
5,640
546
3,680
67,400
Raw
30,198
133,600
5,560
N/A
3,550
63,000
Top of Tank
14,868
48,200
3,210
572
1,840
36,200
Bottom of Tank
26,114
78,400
5,290
548
3,360
58,800
Raw
17,216
69,400
3,990
472
2,470
44,100
Raw
22,419
82,500
4,360
454
3,170
56,700
Raw
23,501
53,825
5,120
538
3,700
43,400
Raw
21,000
79,000
3,860
452
2,850
52,700
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Minimum
14,868
48,200
3,210
429
1,840
36,200
Maximum
30,198
133,600
5,640
572
3,700
67,400
Arithmetic Mean
23,611
78,614
4,683
501
3,102
53,278
Note N/A Not Available
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Raw Leachate Characterization
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Raw Leachate Characterization(Continued)
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Pilot-Scale Leachate Treatment System
ComponentsUS Provisional Patent Number 60/146,553

• Electrolytic Cell
• DC Rectifier
• Recirculating Pump Capable of Operating at 200
  gallons per minute
• 500 Gallon Recirculation Tank and
• Paddle Type Variable Area Flow Monitor with a
  Safety Switch.

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Pilot-Scale Treatment SchematicUS Provisional
Patent Number 60/146,553
To Discharge
SP

D.C. Rectifier
Leachate Addition
Cell
-
Flow Meter
Pump
Electrolyzed Leachate
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SP
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Ash Leachate Pilot-Scale Testing Summary
Pilot Test
Final
Initial
DC Current
Flow rate
Test Volume
Test Duration
Number
Hypochlorite
pH
(Amps)
(GPM)
(Gallons)
Source
(Minutes)
Concentration
(g/L)
1
500
150
400
Leachate
0.971
60
N/A
6.48
38,300
2
500 to 600
158
450
Leachate
0.425
210
N/A
6.50
43,000
3
520 to 605
160
450
Leachate
0.638
240
12.5
6.94
33,600
4
860 to 870
158
450
Leachate
1.23
240
15.5
6.90
33,900
5
800 to 880
160
400
Saltwater
3.13
240
14
7.11
37,300
6
915 to 980
158
450
Leachate
2.68
240
17
6.46
31,000
7
700 to 800
161
450
Leachate
1.77
240
15
9.58
28,800
8
1000 to 1260
158
450
Leachate
1.89
240
22
8.09
29,100
Cell Acid Washed Prior to Pilot Test 9 (7/29/99 -
8/4/99)
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1200
160
450
Leachate
2.38
240
22
7.58
25,700
10
1200
160
240
Leachate
1.59
240
21
6.55
41,400
11
1200
120
450
Leachate
1.12
180
16
6.87
27,300
12
1200
120
450
Leachate
2.76
360
22
7.53
39,100
13
1200
121
450
Leachate
2.54
360
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6.18
37,300
Note N/A Not Available
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Pilot Test 8Initial pH Adjustment (8.09), 1200
Amps, No Cleaning Cycle
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Pilot Test 8 Initial pH Adjustment (8.09), 1200
Amps, No Cleaning Cycle
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Pilot Test 8 - Chemistry Initial pH Adjustment
(8.09), 1200 Amps, No Cleaning Cycle
Ratio of Final
to Initial
Concentration
Parameter
Raw
240 Minutes
Alkalinity (mg/L as CACO3)
128.0
1210.0
9.45
Total Organic Carbon (mg/L)
8.95
7.94
0.89
Chemical Oxygen Demand (mg/L)
390
840
2.15
Total Phosphorous (mg/L)
1.70
1.43
0.84
Chloride (mg/L)
9,313
9,292
1.00
Fluoride (mg/L)
0.11
0.11
1.00
Total Solids (mg/L)
22,031
20,910
0.95
TDS (mg/L)
35,400
38,400
1.08
TSS (mg/L)
114
2
0.02
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Sulfate (mg/L)
513
473
0.92
Specific Gravity
N/A
N/A
N/A
Specific Conductivity (umhos/cm)
29,100
30,700
1.05
pH
8.09
7.94
0.98
Sodium Hypochlorite (g/L)
0.028
1.910
68.21
Note N/A Not Available
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Pilot Test 8 - Metals Initial pH Adjustment
(8.09), 1200 Amps, No Cleaning Cycle
Ratio of Final
to Initial
Parameter
Concentration
Raw
240 Minutes
Aluminum (mg/L)
0.0888
0.0748
0.84
Barium (mg/L)
0.740
0.711
0.96
Calcium (mg/L)
3,930
3,930
1.00
Chromium (mg/L)
0.00676
0.00797
1.18
Copper (mg/L)
0.01300
0.01320
1.02
Iron (mg/L)
0.221
0.170
0.77
Lead (mg/L)
0.00469
0.00143
0.30
Magnesium (mg/L)
4.68
4.58
0.98
Manganese (mg/L)
0.105
0.0961
0.92
Sodium (mg/L)
2,420
2,370
0.98
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Zinc (mg/L)
0.0678
0.0517
0.76
Mercury (mg/L)
lt0.0002
lt0.0002
N/A
Molybdenum (mg/L)
0.0379
0.0311
0.82
Potassium (mg/L)
1,610
1,530
0.95
Nickel (mg/L)
0.0753
0.0778
1.03
Note N/A Not Available
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Pilot Test 13Magnets, Cleaning Cycle
Time
Hypochlorite
pH
Specific
Temperature
DC
(Degrees C)
(Minutes)
Concentration
Current
Conductivity
(g/L)
(umhos/cm)
(Amps)
0
0.000
6.18
37,300
30
1,200
30
0.255
6.27
27,500
32
1,200
60
0.284
6.05
28,000
34
1,200
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0.355
6.09
27,900
37
1,200
120
0.340
5.98
27,900
38
1,200
150
0.454
6.22
27,700
41
1,200
180
0.652
6.61
27,600
43
1,200
210
0.893
7.32
27,300
45
1,200
240
1.250
7.60
26,700
47
1,200
270
1.560
7.71
23,500
49
1,200
300
1.740
7.69
32,800
51
1,200
330
2.070
7.85
33,400
54
1,200
360
2.450
7.86
32,300
56
1,200
360
2.540
7.88
31,400
56
1,200
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Pilot Test 13Magnets Applied, 1200 Amps,
Cleaning Cycle
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Pilot Test 13Magnets Applied, 1200 Amps,
Cleaning Cycle
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Ash Leachate Summary and Conclusions

• These studies showed that liquid sodium
  hypochlorite can be generated from landfill ash
  leachate
• The sodium hypochlorite generated from leachate
  could be used to disinfect wastewater treatment
  plant effluent and then perhaps enter a water
  reuse/recycling system
• Following an initial period of oxidation, the
  present pilot-scale system generated
  approximately 3 g/L of sodium hypochlorite in
  less than 240 minutes of recirculation through
  the Electrolytic cell

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Ash LeachateSummary and Conclusions(Continued)

• Manganese (maximum leachate concentration of 0.4
  mg/L) accumulation on the anodic surface of the
  Electrolytic cell caused a severe loss of
  chlorine production efficiency
• These manganese accumulation problems were solved
  by incorporating a backwashing/cleaning process
  into the pilot-scale system and

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Ash LeachateSummary and Conclusions(Continued)

• Further pilot-scale system optimization is
  necessary to increase the concentration of the
  sodium hypochlorite produced by the system and to
  reduce the recirculation time necessary for
  sodium hypochlorite production.

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Ongoing Ash Leachate Optimization Studies

• Process Optimization
• Increase Hypochlorite Concentration
• Reduce Recirculation Time
• Evaluate Other Methods of Oxidation
• Economic Analysis and Evaluation
• Permitting Process (What will FDEP require?)
• Full-Scale System Costs and Construction

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Proposed EPRI On-Site Sodium Hypochlorite
Generation Study
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Project Team

• FUSE
• University of Pittsburgh
• Black and Veatch
• Exceltec International Corporation
• Test Site
• Sponsoring Utility or Utilities

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Desalination ConcentratePilot-Scale System
To Discharge
SP

D.C. Rectifier
Cell
Concentrate Addition
Flow Meter
-
Electrolyzed Membrane Concentrate
Pump
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SP
NOTE SP Sampling Point
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Trailer Mounted Pilot-Scale Leachate Hypochlorite
System
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Trailer Mounted Electrolytic Cell
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City of Sherman, TexasEDR Concentrate
Analysis(CH2M Hill)
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City of Sherman, TexasEDR Concentrate Analysis
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City of Sherman, TexasMDW Concentrate
Analysis(CH2M Hill)
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City of Sherman, TexasMDW Concentrate Analysis
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Project Goals

• To evaluate the technical operational and
  economic feasibility of electrochemically
  generating liquid sodium hypochlorite from
  desalination concentrate.
• To evaluate the effectiveness and feasibility of
  using this generated sodium hypochlorite for
  disinfecting wastewater treatment effluents prior
  to entering a water reclamation/reuse system.

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Project Tasks

• Task 1 - Concentrate Characterization
• Electrodialysis Reversal (EDR)
• Mineral Water Development System (MWD)
• Task 2 - Pilot-Scale Sodium Hypochlorite
  Generation
• Electrodialysis Reversal (EDR) Concentrate
• Perhaps MWD Concentrate
• Task 3 - Economic/Engineering Analysis
• Task 4 - Disinfection and Water Reclamation/Reuse
  Evaluation
• Task 5 Final Report Preparation and Review
• Task 6 Full-Scale Design and Implementation

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Project Concerns

• Sodium Concentration in the EDR Concentrate
• Possible Chemical Interferences
• Cost Effectiveness
• Final Sodium Hypochlorite Concentration and
  Disinfection Effectiveness

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Project Schedule
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Project PlanData Collection

• Laboratory Analyses Exact number to be
  determined following Task 1
• See Laboratory Analyses
• Cell Operating Parameters
• Concentrate Temperature
• Voltage
• DC Current, etc.

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Proposed Laboratory Analyses

• Mercury
• Molybendum
• Nickel
• Potassium
• Silica
• Sodium as NaCl
• Strontium
• Total Sodium
• Titanium
• Vanadium
• Zinc
• Chlorates
• Borates

• Humic Acid
• Aluminum
• Barium
• Bromide
• Calcium
• Chromium
• Cobalt
• Copper
• Iodine
• Iron
• Lead
• Magnesium
• Manganese

• pH
• Total Suspended Solids
• Dissolved Solids
• Chemical Oxygen Demand
• Total Organic Carbon
• Nitrates
• Chlorine Residual
• Alkalinity as CaCO3
• Fluoride
• Phosphate
• Sulfate

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Potential Applications

• On-Site Sodium Hypochlorite Generation From
  Desalination Concentrate, Membrane Concentrates
  or other High Salt Concentrate Solutions and
• On-Site Sodium Hypochlorite Generation From Ion
  Exchange Backwash.

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