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Nanofiltration Membrane Pilot Studies for Disinfection By-Product Control
by Eric Lynne, EIT
B.S. – Civil and Environmental Engineering (2007) South Dakota State University
Introduction
Objective Preliminary Tests Screening Tests Large Scale Pilot Tests Conclusions
(Bergantine 2007)
Restrictions
Stage 2 D/DBP Rule< 80 μg/L TTHM< 60 μg/L HAA5
Big Sioux River < 1000 mg/L TDS
Energy EfficientHigh Flow at Low Applied Pressure
Background
DBP Problem
Treatment Methods: ChloraminationNF Membranes
Pilot Plant Testing
Background
Chloramination
Low DBPs CreatedEffective
Background – Spiral Wound Membrane
(Hydranautics 2008)
1 2 3
4 5
Background
Membranes
PermeateConcentrateRecoveryStages
(AWWA 1999)
Nanofiltration
PermeateConcentrate
(AWWA 1999)
Background
Membrane Problems
Inorganic ScalingOrganic Fouling
Microbial or Silt Fouling
(Malki 2008, Dow 2008)
Preliminary Testing
Water QualityTOCUV254
SDIAmmonia
Chloramination
Preliminary Testing
ResultsWater Quality
• Well Specific
• UV254 TOC
• SDI: Raw < 5; Feed ~ 1• Naturally occuring ammonia
a) WTP Influent
b) Filter Effluent
Chloramination
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
0 1 2 3 4 5 6 7 8 9 10 11 12Chlorine : Ammonia Ratio
Res
idua
l (m
g/L
)
Free Chlorine Total ChlorineMonoChloramine Free Ammonia
Chloramination56, 59 μg/L TTHM
Chloramination
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
0 1 2 3 4 5 6 7 8 9 10 11 12Chlorine : Ammonia Ratio
Res
idua
l (m
g/L
)
Free Chlorine Total ChlorineMonoChloramine Free Ammonia
Chloramination56, 59 μg/L TTHM
10 μg/L TTHM
Preliminary - Conclusions
Source Water for NF Pilot Plant Direct Nanofiltration of raw water is feasible Filter Effluent is preferred
Chloramination viable alternative with 82% TTHM reduction
NF Membrane Pilot Plants
Phase I – ScreeningKoch TFC-SR2 (K2)Koch TFC-SR3 (K3)Trisep XN45-TSF (T)Hydranautics ESNA1-LF (HE)Hydranautics HydraCoRe-70pHT (HH)Dow/Filmtec NF270 (DF)
(Trisep 2008)
Phase I – Screening
Hold flux constant Vary recovery for each membrane tested
Phase I – Results
TOC and UV254 removal
NF Membrane and Percent Recovery
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
15 50 80 15 50 80 15 50 80 15 50 80 15 50 80 15 50 80K2 K3 T HE HH DF
Per
cen
t R
emov
alTOC UV254
Phase I – Results
TTHM reduction
NF Membrane and Percent Recovery
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
15 50 80 15 50 80 15 50 80 15 50 80 15 50 80 15 50 80K2 K3 T HE HH DF
Per
cen
t R
emov
al87% Minimum Rejection Allowed
Phase I – Results
Concentrate TDS concentration
0
200
400
600
800
1000
1200
K2 K3 T HE HH DF
NF Membrane
Tot
al D
isso
lved
Sol
ids
(mg/
L)
Disposal limit 1000 mg/L
Phase I - Conclusions
Membrane TDS < 1000 mg/L >87% TTHM reduction
Koch TFC-SR2 NO NO
Koch TFC-SR3 NO YES
Trisep XN45-TSF YES YES
Hydranautics ESNA1-LF NO YES
HydraCoRe-70pHT YES NO
Dow/Filmtec NF270 NO YES
Phase II 85% recovery
Variable Flux: 9, 12, 15 gfd
Determine design criteria
Photographs of Pilot Plant
Phase II - Results
TOC and UV254 removal
50%
55%
60%
65%
70%
75%
80%
85%
90%
95%
100%
9* 12 15 9 12 15 9 12 15
K3 T HE
NF Membrane and Flux Rate (gfd)
Per
cen
t R
emov
al
TOC UV254
50%
55%
60%
65%
70%
75%
80%
85%
90%
95%
100%
9* 12 15 9 12 15 9 12 15
K3 T HE
NF Membrane and Flux Rate (gfd)
Per
cen
t R
edu
ctio
n
Phase II - Results
TTHM reduction
87% Minimum Rejection Allowed
Phase II - Results
Adjusted Specific Flux
0.00
0.05
0.10
0.15
0.20
0.25
9* 12 15 9 12 15 9 12 15
K3 T HE
NF Membrane and Flux Rate (gfd)
Adj
uste
d Sp
ecif
ic F
lux
to 2
5°C
(gf
d/ps
i)
Phase II - Results
Ammonia (NH3-N) Removal
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
9* 12 15 9 12 15 9 12 15
K3 T HE
NF Membrane and Flux Rate (gfd)
Per
cen
t R
ejec
tion
Phase II – Results
Fouling
0
0.05
0.1
0.15
0.2
0.25
0 100 200 300 400 500 600 700 800
Hours
Ad
just
ed S
F (
gfd
/psi
)
.
T HE
Phase II – Results
Fouling
0
50
100
150
200
250
300
350
400
0 5 10 15 20 25 30
Days
Con
du
ctiv
ity
(μS
/cm
)
TriSep XN45-TSF
Hydranautics ESNA1-LF
Phase II - Conclusions
Blend Ratio: 44%/56%
Concentrate TDS Increased SF decreased with increasing flux Design Criteria
Applied pressures ranged from 64-165 psi Specific flux values ranged from 0.13-0.21 gfd/psi System recovery rate of 85% Permeate TTHM values ranging from 1.1-2.5 μg/L
No substantial fouling observed
Phase II - Conclusions
Highest Specific Flux = Trisep XN45-TSF Highest TTHM rejection = Hydranautics ESNA1-LF
Membrane Optimum Setting Costs
Koch TFC-SR3 __ gfd ??
Trisep XN45-TSF __ gfd ??
Hydranautics ESNA1-LF __ gfd ??
Recommendations
Cost Data Verify 15 gfd @ 80% recovery Select Hydranautics ESNA1-LF
15 gfd @ 85% recovery (costs?) Consistent Source Water One Membrane for Phase II Challenge Membrane to Foul
Questions