Post on 02-Jan-2017
Adaptation of UV Advanced Oxidation for Inland Potable Reuse Treatment
WateReuse in Texas
San Marcos, TX
July 15, 2016
Michael Watts, PhD, PE, Steven Jones, PhD, PE – Garver
David Sloan, PE, BCEE – Freese and Nichols
Erik Rosenfeldt, PhD, PE – Hazen and Sawyer
What roles can UV AOP fill in a potable reuse
treatment train?
The precedent for UV and UV AOP in Texas direct potable reuse projects
Does UV AOP always need RO pretreatment?
A collaborative research project to assess potential for UV AOP treatment of reclaimed waters of varying quality
• H2O2/UV
• HOCl/UV
Both Texas DPR projects included UV treatment
following RO
Big Spring, TX
Produced
Water
UV AOP
Reverse Osmosis
Microfiltration
Hydrogen Peroxide
Both Texas DPR projects included UV treatment
following RO
Wichita Falls, TX
Produced
Water
UV
Reverse Osmosis
Microfiltration
Not AOP
Reverse osmosis pretreatment improves the
efficiency of H2O2/UV advanced oxidation
RO pretreatment reduces the dissolved organic carbon concentration, which can limit targeted contaminant oxidation
RO pretreatment minimizes photon scavenging by substances other than H2O2
RO pretreatment greatly reduces the concentration of most trace organic contaminants, thereby reducing the competition for available ·OH
Wichita Falls Big Spring
Both TX DPR facilities had neighboring streams
with capacity to assimilate RO concentrate TDS
Big Wichita
River
Big Wichita
River
RO 5 MGD
Permeate
2.5 MGD Reject
Beals Creek
RO2.5 MGD
Permeate
0.9 MGD Reject
A new approach to UV AOP (HOCl/UV) could see
effective treatment of marginal reuse waters
pH
DOC,
mg/L
HOCl/UV
H2O2/UV
Feasibility Curves: 0.5-log MIB
oxidation with ≤ 8 mg/L as Cl2or H2O2 (initial dose)
RO permeate (typical)
UV Dose = 750 mJ/cm2
In 2015, WateReuse Texas sponsored a pilot
study of UV AOP after varying levels of filtration
Secondary
Effluent
Secondary
Effluent
Secondary
Effluent
UV PilotMedia Filtration
NaOCl H2O2oror
In 2015, WateReuse Texas sponsored a pilot
study of UV AOP after varying levels of filtration
Secondary
Effluent
Secondary
Effluent
Secondary
Effluent
UV PilotSubmerged MF
NaOCl H2O2oror
In 2015, WateReuse Texas sponsored a pilot
study of UV AOP after varying levels of filtration
Secondary
Effluent
Secondary
Effluent
Secondary
Effluent
UV PilotSubmerged MF
NaOCl 2 2H2O2
oror
RO
Objectives for the 2015 pilot study
Assess feasibility of novel indirect [·OH] measurement technique in reclaimed waters of varying quality
Test Watts, Rosenfeldt, and Hofmann (2012) steady-state [·OH] model for predicting AOP performance in reclaimed waters of varying quality
Predict degree of UV AOP treatment needed to see micropollutantoxidation in reclaimed waters of varying quality
Initially, each sample from Lawton and Wichita
Falls was surveyed for water quality and trace
organic pollutant profilesMedia Filtration
0
5
10
15
pH Ammonia-N Nitrate-N TOC
UVT = 60%
Initially, each sample from Lawton and Wichita
Falls was surveyed for water quality and trace
organic pollutant profilesMedia Filtration
0
5
10
15
20
pH Ammonia-N Nitrate-N TOC
UVT = 60%
Submerged MF
UVT = 77%
Initially, each sample from Lawton and Wichita
Falls was surveyed for water quality and trace
organic pollutant profilesMedia Filtration
0
5
10
15
20
pH Ammonia-N Nitrate-N TOC
UVT = 60%
Submerged MF
UVT = 77%
RO
UVT = 99%
35000
36000
37000
38000
0
300
600
900
Sucra
lose
CE
C
2,4-
D4-
nony
lphe
nol
4-te
rt-O
ctyl
phen
olAce
sulfa
me-K
Butal
bita
lD
iclo
fena
cG
emfib
rozi
l
Iohe
xal
Iopr
omid
e
ND
MA
Propy
lpar
aben
Sucra
lose
Triclo
carb
an
ng
/L
4-nonylphenol and sucralose were most
prevalent CECs in Lawton effluent samples
The concentrations of iohexol and sucralose
were greatest in MF filtrate from Wichita Falls
40000
45000
50000
55000
0
1000
2000
3000
Su
cra
lose
CE
C
2,4-
D4-
nony
lphe
nol
4-te
rt-O
ctyl
phen
olAce
sulfa
me-K
Butal
bita
lG
emfib
rozi
l
Ibup
rofe
n
Iohe
xal
Iopr
omid
e
ND
MA
NP
YR
Sucra
lose
Triclo
carb
an
ng
/L
Fewer micropollutants were detected following
RO
100
200
300
4-no
nylp
heno
l
4-te
rt-O
ctyl
phen
ol
ND
MA
Sucra
lose
Triclo
san
ng
/L
A sample of each water was also tested for Total
·OH-Scavenging (∑���,� � �)
���� ���,���������∑���,� � ����� ���,���������∑���,� � �
Real-time decay
data collected
for an ·OH-probe
under
UV AOP conditions
(H2O2 and UV)
As expected, Lawton effluent had the greatest
Total ·OH-Scavenging
0.00E+00
2.00E+05
4.00E+05
6.00E+05
8.00E+05
1.00E+06
1.20E+06
Lawton WF MF WF RO
�� ��,��
�,1/�
�� ��,��
�,1/�
Rate of Total ·OH Scavenging
Total ·OH-Scavenging in RO permeate sample
equivalent to nitrite-less MBR effluent
1.00E+04
1.00E+05
1.00E+06
Lawton
WF
MF
WF
RO
Activated S
ludgeE
ffluent
Activated S
ludgeE
ffluent
MB
R E
ffluent
MB
R E
ffluent
No NitriteNo Nitrite
No NitriteNo Nitrite
�� ��,��
�,1/�
�� ��,��
�,1/�
Source: Grant and Hofmann (2016) Water Science and
Technology May 2016, 73 (9) 2067-2073
Each sample was dosed with a chemical
oxidant and pumped at controlled rates through
the annular UV reactor
H2O2 (mg/L)
Lawton: 25
WF MF: 12.5 -17
WF RO: 7 – 8
NaOCl (mg/L as Cl2)
Lawton: 12.5
WF MF: 7.8
WF RO: 4.8
pH
Lawton: 8
WF MF: 7.8
WF RO: 6.5
UV Fluence (mJ/cm2)
Lawton: 282 – 364
WF MF: 458 – 493
WF RO: 711 – 735
Each sample was spiked with 100 ppb 1,4-
dioxane as a probe compound for monitoring
AOP treatment performance
�� ��� ! · #$ � %#$,&'()*+,-.�� ��� ! · #$ � %#$,&'()*+,-.
���� ���,���������∑���,� � ����� ���,���������∑���,� � �
A prevalent artificial sweetener appeared
susceptible to multiple oxidation pathways
0
200
400
600
800
1000
Lawton WF MF
ng
/L
Acesulfame-K
Influent Effluent Model
Influence of NO3, ·Cl?
The most prominent micropollutant in RO
permeate samples, NDMA, was most efficiently
mitigated with UV alone
0
20
40
60
UV
H2O
2/U
V(1
)
HO
Cl/U
V(1)
ND
MA
Re
mo
va
l, %
For equivalent UV fluence
Regulated DBPs may be a concern for
HOCl/UV AOP
0
10
20
30
Dib
rom
oace
tic a
cid
Dic
hloro
acetic
aci
d
Trichl
oroa
cetic
aci
dTot
al H
aloac
etic
Aci
ds (H
AA5)
µg
/L
testH2O2/UV(1)
HOCl/UV(1)
UV
Short-term (<30 minutes)
HAA formation
Short-term (<30 minutes)
HAA formation
Wichita Falls MF FiltratepH: 7.8
Initial Cl2: 7.8 mg/L
pH: 7.8
However, RO removed this short-term HAA
formation potential
RO Permeate UV HOCl/UV H2O2/UV
Dibromoacetic acid ND ND ND
Dichloroacetic acid ND ND ND
Monobromoacetic acid ND ND ND
Monochloroacetic acid ND ND ND
Total Haloacetic Acids (HAA5) ND ND ND
Conclusions Drawn
Trace anthropogenic contaminants (targets for UV AOP oxidation) were detected in all reclaimed water samples, including RO permeate.
In RO permeate, NDMA was detected at greater concentrations than other micropollutants
• UV at AOP doses was most effective treatment for residual NDMA
Is UV AOP necessary following RO? The Wichita Falls DPR Model = RO for organics removal + UV for NDMA destruction
Conclusions Drawn
Upstream treatment processes that can have a significant impact on UV AOP efficiency:
• Denitrification
• Chloramination
• RO
Remaining Questions to Answer
Can disinfection by-product formation be mitigated for HOCl/UV? Without RO?
Which lamp technology will be most effective for HOCl/UV? MP or LP UV?
Expand kinetic model for HOCl/UV to assess potential impact of
• Nitrate/Nitrite in Fully Nitrified Reuse Water
Acknowledgements
• The WateReuse Texas Association
• City of Wichita Falls: Mark Southard, Daniel Nix, and Hunter Adams
• City of Lawton: Afsaneh Jabbar, and LynaNeal
• Trojan Technologies: Adam Festger
• Freese and Nichols: Chris Connolly
• Garver: Kyle Kruger
• Eurofins Analytical: Andy Eaton
Questions?
mjwatts@garverusa.com
Garver
Frisco, TX
(972)377-7480