1

Improved Membrane Design Addresses Integrity Issues for the City of Yuba City Water Treatment

Plant

Richard Stratton, PEHDR Engineering

Acknowledgements

City of Yuba City- John Westhouse, Plant Supervisor- Terrance Pioro, Chief Plant Operator

Yuba City Facts

Founded in 1849

Population – 65,000

Located in Sutter County along Feather River - 43 miles north of Sacramento

Major Area Employers: Sunsweet, Beale AFB

Water Demand Projections

Based on annual average demand of 273 gpc/day

Average

AnnualMax

Day

Buildout Year 2012

37.0

69.5

118.1

020406080

100120140MGD

42.5

85.0

127.0

Peak

Hour

MGD

020406080

100120140

44.0

77.1

13.526.5

40.0

Average

AnnualMax

Day

Peak

Hour

Feather River Water Source

High turbidity (> 200 NTU) during winter storm events

Low turbidity (<5 NTU) during summer

Taste and odor episodes during low flows (fall)

Source Water Quality Used for Membrane Design

Parameters

Summer (May to October) Winter (November to April)

Range 95th Percentile Range 95th Percentile

Temperature, ºC 14--25 23.3 7.2--21 17.8

Turbidity, NTU 1.4--12.3 7.2 1.2--81 17

TOC, mg/L 1.0—3.5 3.1 1.0--5.0 3.95

pH 7.3--7.8 7.7 7.1--8.0 7.8

Alkalinity, mg/L as CaCO3 37--57 51 31--62 58

Hardness, mg/L as CaCO3 34--72 60 44--78 67

Submerged Membrane Selected Because:

Best use of existing infrastructure

Lowest life-cycle costs

Best planning for future

regulatory impacts

Compatibility with existing

treatment processes

Submerged Membrane Design

Designed around two suppliers:

- USFilter/Memcor CMF-S (Siemens)

- Zenon Zeeweed 1000 (GE)

Competitive Bidding:

- Present worth worksheet

- Overall project cost

Pilot Testing

- After membrane selection

- Prior to fabrication to confirm bid assumptions

Two cells 6 mgd capacity each

Memcor CMF-S (Siemens) System Accepted in 2008

Raw

Water

Low Lift

Pumps

Inline-

MixRapid-

MixFlocculation/

Sedimentation

Basin

Dual-

Media

Filter

ClearwellHigh

Service

Pump

Distribution

PACl

Alum

Lime

PAC

CLS

Lime

CLS

HFA

Pol

Lime

PAC

Alum

PACl

CLS

Flocculation

Basin

Screens

Membrane

Filter

Process Flow Schematic

Key Map Layout

Future Membrane Filters

Mixer

Screens

Flocculation

Basins

Membrane Channel

and Basins

CIP and Backwash Area

Pretreatment Varied by Season:

Flocculation Only

Five minutes contact time for Alum and PAC

Provide equalization volume for backwashing

Use existing flocculation and sedimentation basins

Mixer

Summer

Winter

Rapid Mix & Screening

Rapid mix using submersible high-speed mixer

Dual flow band screening (2 mm) to remove solids that may pass through flocculation or sed basins

Submerged Membrane System

Permeate Pumps and Piping in Filter Gallery

Membrane in

Concrete Basins

Membrane Maintenance Provisions

Covers

Bridge Crane

Air Test System

Operations Summary

BW 30 minutes interval, 3 minutes duration

MW 96 hours interval, 40 minutes duration

CIP 30 days interval, 5 hours duration

Filtrate Turbidity 0.04 NTU (avg.)

Feed Turbidity < 10 NTU (avg.)

Water Recovery 97.0% (avg.)

TMP 8.5 psi (avg.)

Flux 30.9 gfd (avg.)

LRV Always > 4.0; typical 4.5

Permeability, gfd/psi@ 20 deg

C

Initial 10.0; End of 30 days 7.5

Membrane Performance with PAC Addition

Membrane Test Performance with PAC Addition

Membrane Permeability Performance*

* Measured after CIP, corrected to 20º C

0

2

4

6

8

10

12

14

Jan Feb Mar Apr May Jun Jul

Permeability,gfd/psi

First Two Years of Operation Summary

Membrane permeability remained high

Treated water quality was excellent

Pressure decay test values began to rise and log removal values fell

Membrane integrity issues became a concern and Memcor was contacted

Memcor began pilot testing in 2010 to gain understanding of problem

Phase 1 Pilot Testing Summary

Pilot testing of the originally installed S10V modules conducted August 2010 through June 2011

Pilot unit experienced same integrity issues as the full scale system

Cause identified as abrasion of the fibers by small particles such as diatoms, which compromised the outer surface of the fibers

Phase 2 Pilot Testing Summary

Pilot testing of the new S10N UF modules conducted August 2011 through June 2012

Pilot unit modules showed dramatic improvement in integrity

TMP remained low and permeability high throughout the test period

Pilot Testing Results for N Module at Yuba City

Integrity Testing Results for N Module at Yuba City

New Memcor Membrane Solves Integrity IssuesNew membrane module “N module” Improvements:

Increase membrane skin thickness, with minimal change to ID/OD - This should decrease the fiber damage when the surface is scratched by abrasive particles

Improved potting chemistry to reduce swelling and cracking

Stopped fiber preservative use to avoid the hollowing effect around the fibers

Memcor Conducting Extensive Testing of New Membrane N Module Testing

- Side-by-side comparison data between old module and new module

- Results very promising - The new module shows much lower PDT decay and higher permeability

- New module testing at Yuba City and West Basin

N Module submitted to NSF for NSF-61 requirements and to meet California Title 22 Alternative Filtration criteria

Siemens Water Recently Commercialized an Enhanced PVDF Hollow Fiber Membrane

Product is available in all hollow fiber membrane applications: potable, reuse, industrial pretreatment to reverse osmosis (RO), seawater desalination pretreatment to RO, and membrane bioreactor (MBR)

Over the past 12 to 15 months, Siemens has validated this product on laboratory-, pilot-, and full-scale installations

Advancements in Permeability and Abrasion Resistance

Research shows membrane permeability of a membrane fiber directly correlates to abrasion resistance of the membrane fiber

• N Fiber after 1 month of

harsh, accelerated

abrasion testing

• Little visible evidence to

suggest degradation

Improved Fiber Morphology Drives System Improvements

…And with the Resulting Permeability Enhancement a Reduction in Pumping Requirements

Contracted Installations with Capacities as of February 2012

Size

(mgd)

Source Location

8 GWUI Northeastern US

6 Clarified Surface Water Southern US

5 Clarified Surface Water Southern US

1 Flashy Surface Water Western US

95 Seawater Source Australia

1.4 Secondary Effluent Southern US

2 Industrial Process Water Asia

4.2 Coagulated Surface Water Source UK

Siemens Memcor® S10N Module Specification

Parameter Details

Module Operating Process Submerged Ultrafiltration

Typical Applications General Applications

Membrane Type Hollow Fiber

Filtration Flow Direction Outside to Inside

Backwash Type Air Scour with Liquid Backwash

Membrane Material PVDF (Polyvinylidene Fluoride)

Other Wetted Module Components Polyurethane, Polyethylene,

Polyamide, EPDM

Nominal Membrane Pore Size 0.04 µm

Nominal Membrane Area 23 m2 / 250 ft2

Nominal Fiber OD/ID 1.03 mm / 0.54 mm

Nominal Module Diameter (Overall) 131 mm / 5.2 inches

Approximate Module Mass 7.5 kg / 16 lbs

131 mm

5.2 in

1,195 mm

47 in

Siemens Memcor® S10N Module Specification cont.

Summary

Yuba City constructed a 12 mgd expansion of their water treatment plant using Memcor submerged membranes in 2008

To address membrane integrity issues Siemens conducted two pilot tests: one with the existing S10V, and the new S10N

The results of the S10N membrane testing were very encouraging, with LRV values greater than 4.0 with only minor pinning

Summary (cont’d)

Based on testing results at Yuba City and other locations, Memcor has begun production of the new modules for future projects

Approval to operate granted by Redding office of CDPH -final approval for Alternative Filtration criteria is expected soon

New modules installed in May 2013 and have been operating well – new Flux = 36.5 gfd