Valley City Membrane Water Treatment Plant · 2000. 8. 31. · Valley City Membrane Water Treatment...

Education and Support for Membrane Treatment Operators

NWMOA Technology Transfer Workshop“Membrane Plant Upgrades”

Ogden, UT – August 30, 2016

1

Valley City Membrane Water Treatment Plant

Scott BueckerAdvanced Engineering and

Environmental Services (AE2S), Inc.

©NWMOA

Education and Support for Membrane Treatment Operators 2

Overview

Water Resources and Infrastructure

O&M of Ultrafiltration (UF) Membrane System

O&M of Reverse Osmosis (RO) Membrane System

Conclusions and Lessons Learned

©NWMOA


Overview

Population of 6,585

On the Cheyenne River in SE North Dakota

“City of Bridges”

©NWMOA


Overview

Source water

Groundwater is primary source ~ 60%

Cheyenne River – 40%, high in sulfate and dissolved

solids (TDS). Gets overflow from Devils Lake, a

closed basin

©NWMOA


Raw Water Sources

5

Well #6

WATER

TREATMENT

PLANT

RIVER INTAKE

Well #5

Well #4

Pump

Station


Overview

$21M UF/RO upgrade, replacing conventional lime

softening, completed in late 2011

Designed to enable compliance with SMCLs

250 mg/L for sulfate SO4

500 mg/L for Total Dissolved Solids

RO Reject (brine) is discharged to retention basin –

up to 6 month storage capacity, then discharged to

Sheyenne during high flows

©NWMOA


Infrastructure

7

Original Plant

Pump House

ClearwellRO Addition


Former Treatment Processes

©NWMOA

Pretreatment (Settling)

Lime Softening

Gravity Rapid Sand Filtration

Re-Carbonation

Constructed in 1974

4 MGD


Phased Construction

©NWMOA

Phase 1:

Conversion of Pre-treatment Basin to UF Membrane System

Phase 3:

Conversion of Softening Basin to Pre-treatment Basin

Phase 1:

Phase 2:

Conversion of Media Filters to RO Wetwell


UF Design Basis

Membrane Elements: Zenon ZeeWeed 1000

Membrane Housing: 64M (only 48 populated)

Design Flux: 18-24 GFD

©NWMOA


UF Membrane Area – 4 Trains

©NWMOA


1 Train = 3 Cassettes

©NWMOA


General Facility Photos

©NWMOA


Water Temperature

©NWMOA

72.0

42.0


UF Flux

©NWMOA

Flux is inversely proportional to the viscosity of

the permeate

Viscosity of water increases as temperature

decreases


UF Temperature Corrected Flux

©NWMOA


UF Transmembrane Pressure (TMP)

©NWMOA

~ 1.5 psi

~ 3.5 psi


Fouling

Accumulation of substances on membrane surface

or within the pores that decreases permeability

Colloidal

Scaling

Biofouling

More rarely: Antifoaming agent or Protein

Typically, more than one of these is involved

©NWMOA


Valley City Irreversible Fouling

Based on small-scale autopsy performed by GE, VC

fouling is mostly organics, with lesser amount due to a

Barium Salt

Operations modifications:

Enhanced coagulation – reduce TOC loading

Proprietary GE chemical cleaning agent

More aggressive backpulse and CIP regime

©NWMOA


UF Permeability

©NWMOA


UF Log Removal

©NWMOA


UF Permeate Turbidity

©NWMOA


RO Design Basis

Membrane Housing: Three GE MUNI 1.0 Skids

Membrane Elements: GE High Recovery, Low

Energy (HR LE Series) – Thin Film Membrane

(TFM)

Polyamide layer on top of a polyethersulfone

(PES) layer on top of a non-woven fabric support

sheet. Three layer configuration provides high

rejection of salts, high filtration rate, and good

mechanical strength

©NWMOA


Design Criteria:

200 psi feed pressure

Feed Water NTU < 1.0, SDI < 5

10-20 GFD flux

Design Rejection: 99.0%

RO System Design

28


Temperature Affects

Temperature

Pressure

Rejection

Suspected minor damage

to this skids integrity



©NWMOA


Online Chemical Feeds

Pre-UF Membranes

Sodium Permanganate – Oxidation of Manganese

Sulfuric Acid – pH Adjustment

Aluminum Chlorohydrate (ACH)

Pre-RO Membranes

Sodium Bisulfite – Oxidant Neutralizer

Antiscalant

Post RO/UF Mixing

Sodium Hydroxide – pH Adjustment

©NWMOA


Offline Chemical Feeds (CIP)

Ultrafiltration Membranes

Citric Acid

Sodium Hydroxide

Sodium Hypochlorite

Sodium Bisulfite

Proprietary GE chemical for organics removal

Reverse Osmosis Membranes

Sodium Hydroxide

Citric Acid

©NWMOA


Plant pH Profile

pH:

Raw water: 8.3

RO Feed: ≤ 7.0

RO Permeate: 5.5

RO Concentrate: 7.8

Degasifier Effluent: 6.2

Final Plant Effluent: ~ 8.4, down from 8.9

©NWMOA


Other Issues

4 mgd Facility treating about 600,000 gpd

Frequent shutdowns, but able to limit to less than 24

hours

Permeate flush for RO

©NWMOA


Conclusions and Lessons Learned

After over 4 years of operation, Valley City MWTP is

running within design parameters

Water temperature has substantial impact on

performance

UF: Flux, TMP, Permeability

RO: Rejection, Pressure, Degasifier Performance

Proper maintenance and integrity testing is crucial for

‘staying ahead’ of UF system performance issues

On/off operation of treatment systems can affect turbidity

analyzer performance

©NWMOA

Valley City Membrane Water Treatment Plant · 2000. 8. 31. · Valley City Membrane Water Treatment...

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