RO/NF

UFMBR

Chemicals

CAS E STUDY
RO | UF | MBR |Wastewater Treatment
California, USA

Water Replenishment District of Southern California Incorporate Direct- Coupling ofToray UF to Toray RO for High Recovery and Energy Savings

CHALLENGE

DIRECT-COUPLING DESIGNThe Water Replenishment District of Southern California (WRD)
manages the groundwater resources that supply water to the Los
Angeles region. Recently surviving an eight-year drought, WRD
established the Water Independence Now (WIN) initiative to "endthe district's reliance on imported water from the Colorado Riverand Northern California for groundwater replenishment." As aresult, WIN incorporates a suite of projects that maximizes the useof locally available water sources. The most significant componentof the WIN program is the Albert Robles Center for Water Recycling& Environmental Learning (formerly known as the Groundwater
Reliability Improvement Project or GRIP). Through the program,
WRD aims to provide 4 million residents in the Los Angeles region
with an entirely local sustainable groundwater supply, eliminating
its dependence on 25,000 AFY of imported water from theColorado River and Northern California.

Process design features focused on achieving the smallest footprint
and lowest capital and operation costs, particularly energy. As aresult, a direct coupling of UF to a first and second stage primary RO
feeding and a third stage secondary RO for concentrate recovery isin place. The direct coupling, the method of feeding the UF filtrate
directly to the RO, eliminates the need for a break tank and associatedequipment to store the UF filtrate/RO feedwater. Historically, this typeof arrangement reduces the risk of biological growth within the breaktank, thus reducing the RO system's contamination risk in seawater
desalination systems. However, as wastewater sources may containhigh levels of organics, this design was essential in energy savings
from the reduced footprint.

The advanced water treatment facility (AWTF) treats 14.8 MGD
of tertiary municipal wastewater from the San Jose Creek Water
Reclamation Plant through Toray UF pressurized hollow-fiber
ultrafiltration modules followed by Toray RO reverse osmosis
membrane elements. The RO product water moves to a final
advanced oxidation ultraviolet step. Tetra Tech (Pasadena, CA)engineered the system to meet the district’s requirements, while
Biwater, Inc. was hired as the original equipment manufacturer tobuild the treatment systems.

Figure 1: Albert Robles Center

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CASE STUDY
RO | UF | MBR |Water Replenishment District of Southern California Incorporate Direct- Couplingof Toray UF to Toray RO for High Recovery and Energy Savings

Table 1 — UF Specifications
Item

Primary UF

Secondary UF

Model

HFU-2020HN

HFU-2020N

Number ofElements per Train

8030

Number ofTrains

104Membranesurface per Train

62,000 ft2

23,250 ft2

Net Flux (GFD)

38.0

11.9Recovery

96%90%

Total Recovery

99.6%

Figure 2: Direct-Coupling Design
Two Statges of Ultrafiltration
Three Stages of Reverse Osmosis

RESULTS

Table 2 — RO Specifications

Toray's PVDF hollow-fibers exhibit one of the strongest membrane chemistries in
the industry, allowing the production of more filtrate per module compared to othermanufacturers.

ItemPrimary RO

Secondary RO

Model

TMG20D400SR

TMG20D400SR

Number of Trains

42

Number of Stages

21

Membrane Array
per Train

72:30

16

Numbr of Elementsper Vessel

77

Average Permeate
Flux (GFD)

11.9

10.3

Recovery

85%50%The RO system is a three-stage configuration to provide the most efficient designfor high recovery (92.5%). Separating the primary RO (PRO) from the third stage RO(TSRO) units allows more operational flexibility. Operations can remove the TSRO
stage for cleaning or other maintenance without affecting the PRO operation and viceversa. Selecting Toray RO for the three-stage RO process accomplished the facility's
goals of higher rejection and lower energy. Also, by combining Toray UF, recovery of
99.6%, and Toray RO, recovery of 92.5%, membranes, they met the overall desired
system recovery of 92.1% and an estimated energy savings of 500,000 kW/yr.

Total Recovery

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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. © 2022 Toray Industries, Inc. Subject to change without notice.
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92.5%