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Andy Komor, MS, PE
Pacific Advanced Civil Engineering, Inc. (PACE)
2013 CA-NV AWWA Fall ConferenceSeptember 30 – October 3, 2013Sacramento, California
Keisuke Ikehata, PhD, PE, PEng
Fiona (Yao) Jin, MS, EIT
James A. Mattews, PE
Janet A. Fordunski, MS, PE
Outline Background shows multiple problems: Fe, Mn, Ur,
THMs, Hardness
On-site pilot test of expansion: NF versus GAC
Results: water quality, costs, maintenance
Conclusions
Existing Well Water Contains Mn, Fe, Uranium, Hardness, and Recently THMsParameters Unit Well Water
pH - 7.8
Total Dissolved Solids (TDS)
mg/L 722
Alkalinity mg/L as CaCO3 150
Hardness mg/L as CaCO3 310
Iron mg/L 0.23
Manganese mg/L 0.154
Uranium µg/L 72
Total Organic Carbon (TOC)
mg/L 1.4
Abbreviation: MCL = maximum contaminant level, NA = not applicableNote: *Secondary MCL
Existing Treatment Reduces Manganese, Iron, and Uranium Only
MnO2 Filter
NaOCl(~2 mg/L)
Wells
Ion Exchange
NaOCl(~ 2 mg/L)
Distribution System
Fe and Mn Removal(Pre-oxidation + Reactive
Media Filtration)
Uranium Removal (Anion
Exchange)
Secondary Disinfection
Existing Filtration Plant Removes Mn, Fe, and U… but not Hardness or TOCParameters Unit Well Water
TreatedWater
Federal MCL
pH - 7.8 7.9 6.5-8.5*
Total Dissolved Solids (TDS)
mg/L 722 713 500*
Alkalinity mg/L as CaCO3 150 170 NA
Hardness mg/L as CaCO3 310 270 NA
Iron mg/L 0.23 <0.02 0.3*
Manganese mg/L 0.154 0.022 0.05*
Uranium µg/L 72 11 30
Total Organic Carbon (TOC)
mg/L 1.4 1.4 NA
Abbreviation: MCL = maximum contaminant level, NA = not applicableNote: *Secondary MCL
Trihalomethanes Were Emerging…TOC Removal Required
Disinfection by-products
Total trihalomethanes (TTHM) in drinking water exceeded maximum contaminant level (MCL): 80 µg/L
Brominated THMs
Bromodichloromethane (CHBrCl2)
Dibromochloromehtane (CHBr2Cl)
Bromoform (CHBr3)
TOC (THM precursors) must be removed
NF and GAC Were Selected for Pilot Testing
Options for organics removal
Nanofiltration (NF)
Granular activated carbon (GAC)
Ozone
Not suitable because of high bromide (Br-) concentration (>0.6 mg/L)
High risk of bromate (BrO3-) formation
Coagulation
Not suitable because of the site-specific limitations
NF vs. GACNF GAC
Pros
Lower media replacement cost
Removes not just organics
Reduces scaling at point of use
Cons
Higher capital cost
More elaborate operations
Water loss (generally)
Pros
Lower capital cost
No additional water loss
Simpler operation
Cons
Media disposal and replacement
Higher operational cost
Removes only organics
NF Provides Additional Benefits
Removal of hardness and salinity with less water loss compared to existing Hot Water RO and IX Polishing at Point of Use
Take uranium treatment process offline, decreasing salt addition from regeneration, radioactivity of spent material, and maintenance
MnO2 Filter for Iron and Manganese
Removal
Ion Exchange for Uranium
Removal
NaOCl
P
Nanofiltration
DistributionSystem
NF-treated Water
NF Concentrate
GAC-treated Water
CartridgeFilters
Antiscalant
Wells
NaOCl
Existing Water Treatment Plant
Nanofiltration(NF)
Granular Activated Carbon
(GAC)
P
GAC-1GAC-1GAC-1GAC-2GAC-2GAC-2
NF System Configuration Membrane element (Dow Filmtech NF90-2540)
Size
Diameter: 2.5 inches
Length: 40 inches
Type: thin-film composite
Material: polyamide
Feed flow rate: 6 gpm
Stabilized MgSO4 rejection: >97.0%
Five elements in-series
Concentrate recirculation
NF System Configuration Cartridge filters
Outside diameter = 2.5 inches
Inside diameter = 1 inch
Lengths = 9.75 inches
5 µm & 1 µm
Antiscalant injection
SpectraGuardTM from Professional Water Technologies, Inc.
GAC Media GAC-1
Norit DARCO® 12x20 Lignite coal
Mesh size : 12 x 20
Larger mesh size
Acid wash carbon
GAC-2
Siemens AquaCarb® 1230AWC Coconut shell
Mesh size : 12 x 30
Smaller mesh size
Acid wash carbon
Operation Parameters
NF
NF recovery rate = 85%
Hydraulic pressure = 150 ~ 170 psi
Feed flow rate = 1.2 gpm
GAC
Flow rate = 0.15 gpm
Pre-chlorine injection was halted during the pilot test to protect the NF membrane
Monitoring Parameters Trihalomethane formation potential (THMFP)
Organics
Chemical oxygen demand (COD)
Total organic carbon (TOC)
Iron
Manganese
Uranium
Total dissolved solids (TDS)
MnO2 Filter for Iron and Manganese
Removal
Ion Exchange for Uranium
Removal
NaOCl
P
Nanofiltration
DistributionSystem
NF-treated Water
NF Concentrate
GAC-treated Water
CartridgeFilters
Antiscalant
Wells
NaOCl
Existing Water Treatment Plant
Nanofiltration(NF)
Granular Activated Carbon
(GAC)
P
GAC-1GAC-1GAC-1GAC-2GAC-2GAC-2
Sampling Locations
Note: Samples were also collected at the existing RO plant.
THMFP Was Reduced by Both GAC and NF
0
10
20
30
40
50
60
THM
Fo
rmat
ion
Po
ten
tial
(µ
g/L
)
Sampling Point/Treatment
Chloroform (µg/L)
Dichlorobromomethane (µg/L)
Chlorodibromomethane (µg/L)
Bromoform (µg/L)
< 1 µg/L < 1 µg/L < 1 µg/L
*
Note: *RO feed already contained THMs.
THM Precursors Were Removed by Both NF and GAC
ParametersFeed
WaterNF
TreatedGAC*
Treated
COD (mg/L) 2.7 <0.7 <0.7
TOC (mg/L) 1.4 <1.0 <1.0
Note: *No difference between two GAC media.
Uranium Was Removed by NF and GAC
0
10
20
30
40
50
60
70
80
Feed NF Treated GAC-1 GAC-2
Ura
nim
(µ
g/L
)
Treatment
1st Week
2nd Week
< 1 µg/L < 1 µg/L
USEPA Primary MCLfor Uranium (30 µg/L)
Note: GAC adsorbed uranium and spent media exhibited a hazardous level of radioactivity.
Only NF Removed Iron and Manganese
0
0.01
0.02
0.03
Feed NF Treated GAC-1 GAC-2
Iro
n (
mg
/L)
and
Man
gan
ese
(m
g/L
)
Treatment
Iron
Manganese
Note: As iron and manganese may precipitate and foul NF membranes, MnO2 filters will be necessary regardless.
MnO2 Filter Performance during Pilot Test without Pre-chlorination
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
Iro
n a
nd
Man
gan
ese
(m
g/L
)
Date/Time
Iron - Raw Well WaterMn - Raw Well WaterIron - After Iron & Mn FiltersMn - After Iron & Mn Filters
US EPA Secondary MCL for Iron (0.3 mg/L)
US EPA SecondaryMCL for Manganese (0.05 mg/L)
NF Removed Majority of TDS and Hardness
0
100
200
300
400
500
600
700
800
Co
nce
ntr
atio
n (
mg
/L)
Orthophosphate
Nitrate
Sulfate
Chloride
Bicarbonate
Magnesium
Calcium
Manganese
Iron
Potassium
Sodium
Note: The PACE pilot NF unit was operated at 85% recovery, while the Hot Water RO was operated at 50% Recovery.
Cost Estimate
TreatmentOptions
Capital Cost Annual O&M
GAC $ 309,900 $ 83,500/year
NF $589,300 $ 68,000/year
Note: Assuming GAC media replacement every ~2 months.
NF has the Following Benefits
Better water quality
Lower TDS and hardness
Lower O&M costs
May replace existing ion exchange for uranium removal and hot-water RO with NF
Reduce flow to WWTP by 20%
New
NF
Conclusions Both NF and GAC achieved satisfactory levels of
organics and THMFP removal
NF was recommended because it would provide additional benefits Removal of uranium, hardness and TDS No hazardous (radioactive) spent media
Lower O&M costs No frequent media replacement
Reduced scaling without RO/IX
Decommission existing uranium removal
Reduces flow to WWTP
Conclusions (Continued) GAC has been selected,
designed and constructed
Lower capital cost
Less operational complexity
However, replacement of the existing RO facility with smaller NF is being considered
Thank you!
Contact Information
Andy Komor, MS, PE
Email: akomor@pacewater.com
Phone: 714-481-7225
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