RO/NF

UFMBRChemicals

C A S E S T U DY
RO | UF | MBR |Drinking Water
Texas, USA

Retrofit Expansion of an Ultrafiltration System Using Toray UF Modules
at Granbury's Surface Water and Treatment System
INTRODUCTION
The Brazos Regional Public Utility Agency (BRPUA)
in Texas operates the Surface Water and Treatment
System (SWATS) that treats water from Lake
Granbury, fed by the Brazos River. The SWATS facility
first began operating in 1988 with clarification,
dual media filtration, and electrodialysis reversal(EDR). The plant was upgraded in 2001 to includeultrafiltration (UF) and reverse osmosis (RO)membrane treatment to produce higher qualityeffluent.
The plant's first retrofit and expansion of the UF
modules and system, respectively, took place in2008 to produce up to 10 MGD. After several yearsof operation, the membrane modules exhibited
fiber breakage, and the utility recognized an
opportunity to upgrade the existing UF systemand consider room for future expansion.
Figure 1: UF/RO system designed and constructed by
WesTech Engineering

CHALLENGEBRPUA worked with the utility's consulting firm, Enprotec,Hibbs & Todd (eHT), to assess the pros and cons of a UF module
retrofit versus system replacement. The following assessments
were made:Table 1: UF comparison

Previous UF

HFU-2020N

Total no. of trains

5Max. no. of modules per rack78

No. of UF modules per rack

78

50

Total no. of UF modules

390

250

9.2 MGD

10.0 MGD

UF system capacity
Membrane material
Nominal pore size of membrane

03-US-MB2-TX-202108

Because the UF racks were fully occupied, a 1:1 replacementof the UF modules would limit the room for expansion, taking
into consideration future demands for water.

2.

Replacing the entire UF system would be uneconomical as
much of the system components (instrumentation, valves,and pumps) had many years of serviceable life remaining.

3.

However, if the system were retrofitted using UF modules
with higher flux, this would minimize modification of systemfootprint and produce equal or better effluent. Furthermore,
the plant could meet not only the current capacity with fewer
modules but also allow for expansion within the existing
footprint and save costs for many years to come (Nay 2017).

PVDF
N/A

0.01 µm
775 ft2

Effective membrane area per module
Commissioned

1.

2008

March 2017

A Request for Proposal (RFP) was released, calling for systemmanufacturers to submit a membrane treatment design thatmaximized the 'repurposing' of the existing racks and trains andproduce a minimum of 2.0 MGD and a maximum of 3.0 MGD.

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Retrofit Expansion of an Ultrafiltration System using Toray UF Modules
at Granbury's Surface Water and Treatment SystemC A S E S T U DY
RO | UF | MBR

TORAY UF MODULES
Technical reviews and projections showed that Toray's pressurized
UF modules (p/n HFU-2020N) could meet the prequalification
requirements. They are listed below:••

The system would require a total of 250 Toray UF modules tosatisfy the minimum total system capacity of 10.0 MGD, which isa sizeable 140 modules less than what the previous UF system
was using.
A total of 380 Toray UF modules would be required to meet themaximum total system capacity of 15.0 MGD, which still leftroom for expansion.

Toray UF modules were selected for piloting from December 2015
to January 2016 to confirm that the UF modules can meet thedesign conditions for the full-scale plant and also drinking waterrequirements based on the Texas Commission on Environmental
Quality's (TCEQ) guidelines.
The pilot study would be conducted in two phases where an RO
unit was included to mimic the full-scale design but also to study
how UF as a pretreatment to the RO system affects performance.
Phase 1 of the study measured the performance of the UF
membrane and whether it could meet design objectives, while
Phase 2 evaluated both performances of the UF and RO. The pilot
results of Phase 1 are shown in Table 2.

Successful piloting confirmed design projections, and the utility/
consultant selected WesTech Engineering (www.westech-inc.com) as
the OEM using Toray UF modules for the retrofit.
CONSIDERATIONSThis study illustrates the key factors of whether or not a retrofit
is the best option for a plant. It helps to examine further thepros and cons of maintaining a proprietary system versus
implementing a non-proprietary system as we observe themarket shifting towards the latter (Berryhill. 2016). Such cases
help drive the improvement of membrane technologies and meetthe needs of the customer by offering flexible options that havelong-term benefits.
REFERENCES
Berryhill, Joshua. "Membrane troubleshooting and replacement
at Brazos Regional Public Utility Agency Surface Water andTreatment System." South Central Membrane Association
Workshop, Broken Arrow, Oklahoma. April, 2018.
Nay, Jason. Linton, Libbie. Richard, Alain. Berryhill, Joshua. Dye,Dan. "Retrofit and expansion of a 10 MGD UF system in Granbury,
Texas." AMTA/AWWA Membrane Technology Conference, Long
Beach, California. February 2017.

Table 2: Pilot results
Membrane module

HFU-2020N

Flux at design temperature (20°C)

60.3 gfd

Production cycle time

34 minutes

Backwash flow rate

1.1 times x production flow rate

Average TMP

11.0 psi

Average recovery

97%

Maintenance clean frequency

2 times per week

MC chemical solution

Sodium Hypochlorite 250 ppm

Fiber breakage

Zero fiber breaks or repairs

Figure 2: 3D CAD model of UF
rack after the retrofit using Toray UF
showing additional room for expansion.
Image courtesy of WesTech Engineering, Inc.

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All information presented herein is believed reliable and in accordance with accepted engineering practices. Toray makes nowarranties as to the completeness of this information. Users are responsible for evaluating individual product suitability forspecific applications. Toray assumes no liability whatsoever for any special, indirect or consequential damages arising from thesale, resale or misuse of its products. © 2021 Toray Industries, Inc. Subject to change without notice.
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