CASE STUDY
RO | NF | UF | MF

Lake Granbury SWATS
Municipal Drinking WaterGranbury, Texas

Retrofit Expansion of an Ultrafiltration System at Granbury's Surface Waterand 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 has been in operation since 1988 and initiallycomprised of clarification, dual media filtration, and electrodialysis
reversal (EDR) until the plant was upgraded in 2001 to includeultrafiltration (UF) and reverse osmosis (RO) membrane treatment
to produce higher quality effluent.
The plant's first retrofit/expansion of the UF modules took placein 2008 with the goal of producing up to 10.0 MGD. After several
years of operation, the membrane modules exhibited fiber
breakage, and in anticipation of a projected increase in demand
for water, the utility decided it was time for another upgrade.
CHALLENGE
As the UF racks were already fully populated (5 trains with 78
modules per train), this eliminated the possibility for future
expansion with a 1:1 replacement of the modules. The alternative
would be to replace the entire system, but much of the systemcomponents, such as instrumentation, valves, and pumps, still
had many years of functional life remaining, and this option too
would be unfavorable. The last option considered was to retrofit
with another type of UF module that would have higher flux while
maintaining the same footprint, have minimal modifications tothe existing racks, and produce equal or better effluent. With thissolution, the plant could meet not only the current capacity withfewer modules but also allow for expansion within the existing
footprint and save costs for many years to come (Nay. 2017).
As a result, the utility teamed up with the consulting firm Enprotec,
Hibbs & Todd to draft and release a Request for Proposal (RFP) tosystem manufacturers. The RFP would require manufacturers toprovide a membrane treatment scheme that could maximize the'repurposing' of existing racks and trains. Additionally, within thesame footprint, the RFP would also require each of the UF trains toproduce a minimum of 2.0 MGD up to a maximum of 3.0 MGD.

MC-CS-GRANBURY-UF-1902

UF/RO system designed and constructed by WesTech Engineering(WWW.WESTECH-INC.COM )Quick Facts — UF comparison

Previous UF

HFU-2020N

Total no. of trains

5Max. no. of modules per rack78

No. of UF modules per rack78

Membrane material
Nominal pore size of membrane

PVDF
N/A

0.01 µm
775 ft2

Effective membrane area per module
Total no. of UF modules

50

390

250

UF system capacity

9.2 MGD

10.0 MGD

Commissioned

2008

March 2017

WWW.TORAYWATER.COM

Case Study

Retrofit Expansion of an Ultrafiltration System at Granbury's Surface Water and Treatment System
SOLUTIONCONSIDERATIONSTechnical reviews and projections showed that Toray's TORAYFIL™
pressurized UF modules (p/n HFU-2020N) could meet theprequalification requirements. To satisfy the minimum total
system capacity of 10.0 MGD, it would require a total of 250 TorayUF modules, which was a considerable 140 modules less thanthe previous installation. Secondly, to meet the maximum total
system capacity of 15.0 MGD, there would be required a total of380 modules, which still left room for installation of additionalmodules. For evaluation of performance based on the Texas
Commission on Environmental Quality's (TCEQ) guidelines andrequirements, Toray's UF module would be selected for piloting
from December 2015 to January 2016.

This study exemplifies the key factors that go into deciding onwhether or not a retrofit is the best option for a plant and to
examine further the pros and cons of maintaining a proprietarysystem versus implementing a non-proprietary system as we
observe the market shifting towards the latter (Berryhill. 2016).
Such cases help drive the improvement and advancement of
membrane technologies and meet the needs of the customer byoffering flexible options that are also viable in the long run.

Successful piloting confirmed design projections (results shownin Table 2), and the utility/consultant partnered with the OEM
WesTech Engineering to use Toray's UF modules for the retrofit.

REFERENCES
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.
Berryhill, Joshua. "Membrane troubleshooting and replacement atBrazos Regional Public Utility Agency Surface Water and Treatment
System." South Central Membrane Association Workshop, Broken
Arrow, Oklahoma. April, 2018.

Table 2: piloting results
Membrane module

TORAYFIL™ 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 1: 3D CAD model of UF
rack after the retrofit showing additionalroom for installation. Image courtesy ofWesTech Engineering, Inc.

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t: +1 (858) 218 • 2360 f: +1 (858) 218 • 2380 e: INNOVATION@TORAYMEM.COM™

and® are trademarks of Toray Industries, Inc., its subsidiaries or affiliates in some countries.

All information presented herein is believed reliable and in accordance with accepted engineering practices. Toray makes
no warranties 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. ©2019 Toray Membrane USA, Inc. Subject to change without notice.
MC-CS-GRANBURY-UF-1902