Adaptation of UV Advanced Oxidation for Inland Potable Reuse ...

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



Secondary

Effluent

Secondary

Effluent

Secondary

Effluent

UV PilotSubmerged MF

NaOCl H2O2oror



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%




0

5

10

15

20


UVT = 60%

Submerged MF

UVT = 77%




0

5

10

15

20


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?

[email protected]

Garver

Frisco, TX

(972)377-7480

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