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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