Transcript No Slide Title

Considerations for Brackish Groundwater
Use as a Water Supply for Small Water
Systems and Municipalities
Eddie C. Livingston, MSCE, P.E.
Livingston Associates, P.C.
NM Brackish Groundwater Aquifer Assessment Workshop
Albuquerque, NM
January 15, 2004
LIVINGSTON ASSOCIATES, P.C.
Consulting Engineers
Saline GW in NM
20% fresh <1,000 ppm TDS
 50% brackish water 1,000 - 3,000 TDS
 25% brackish water 3,000 - 10,000 TDS
 5% saline water >10,000 ppm TDS
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– (source: NM Bureau of Mines & Mineral
Resources, 1965, Mineral and Water
Resources of New Mexico: Bulletin 87)
LIVINGSTON ASSOCIATES, P.C.
Consulting Engineers
Establish Water Quality Goals
Meet USEPA/NMED primary and
secondary drinking water standards
 TDS <500 mg/L
 Sulfate <250 mg/L
 or will <1,000 mg/L TDS be acceptable?
 Match current quality?
 End user decision
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LIVINGSTON ASSOCIATES, P.C.
Consulting Engineers
Desalting Technologies
Reverse Osmosis (RO) - Pressure driven
membrane ion separation process
 Electrodialysis Reversal (EDR) - Low
voltage electrical ion separation process
 Ion Exchange (IX) - Replaces select
ions for another (sodium for hardness)
 various thermal (distillation) processes
 New technologies
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LIVINGSTON ASSOCIATES, P.C.
Consulting Engineers
RO Membrane
FEED SIDE
(HIGH PRE SSURE )
SALTS
SALTS
MEMBRANE
PERMEATE SIDE
(LO W PRESSURE)
LIVINGSTON ASSOCIATES, P.C.
Consulting Engineers
Ion Rejection
Typical Reverse Osmosis Membrane Ion Rejections
Ion
Reject
Ion
Reject
Ion
Aluminum
99%+
Chloride
95-97% Magnesium
Ammonium 88-95% Chromate
90-98% Manganese
Arsenic
94-96% Chromium
96-98% Mercury
Barium
96-98% Copper
98-99% Nickel
Bicarbonate 95-96% Cyanide
90-95% Nitrate
Borate
35-70% Ferrocyanide
99%+
Phosphate
Boron
60-70% Fluoride
94-96% Potassium
Bromide
94-96% Hardness
96-98% Selenium
Cadmium
96-98% Iron
98-99% Silica
Calcium
96-98% Lead
96-98% Silicate
LIVINGSTON ASSOCIATES, P.C.
Consulting Engineers
Reject
96-98%
98-99%
96-98%
98-99%
93-96%
99%+
95-97%
96-98%
85-90%
95-97%
Ion
Silver
Sodium
Strontium
Sulfate
Sulfite
Thiosulfate
Zinc
Reject
85-97%
95-98%
96-99%
99%+
98-99%
99%+
98-99%
RO Terms
Feed water (BW supply)
 Permeate (product) treated water
 Brine (concentrate) rejected salt stream
 Recovery: percent of product water to
feed water (ie; if feed = 100 gallons,
and product = 75 gallons then recovery
is 75%)
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LIVINGSTON ASSOCIATES, P.C.
Consulting Engineers
Example RO Performance
Feed
 TDS = 2,250 mg/L
 Cl = 189 mg/L
 SO4 = 1,220 mg/L
 Ca = 353 mg/L
 Hard = 1404 mg/L
 pH = 7.3
Product
 25 mg/L
 5 mg/L
 5 mg/L
 3 mg/L
 12 mg/L
 6.0
LIVINGSTON ASSOCIATES, P.C.
Consulting Engineers
WELL BY-PASS
FOR BLENDING
PRE-FILTERS
TO DISTRIBUTION
RO
PERMEATE
RO ARRAY
HIGH PRESSURE
PUMP
POST-TREATMENT
CHEMICAL FEED
(ACID, SCALE
INHIBITOR)
BRINE
DISPOSAL
WELL
LIVINGSTON ASSOCIATES, P.C.
Consulting Engineers
Horizon City 6 MGD RO
LIVINGSTON ASSOCIATES, P.C.
Consulting Engineers
MEMBRANE SCALING
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Scale formation on
membrane surface
Sparingly soluble salts
(CaSO4, BaSO4)
Will cause “tail-end”
membrane scaling
Increased operating
pressure and decrease
in salt rejection
LIVINGSTON ASSOCIATES, P.C.
Consulting Engineers
BWRO Problem Salts
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CaSO4
BaSO4
SrSO4
CaCO3
CaF
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Fe
Mn
Al
SiO2
LIVINGSTON ASSOCIATES, P.C.
Consulting Engineers
Concentrate Disposal
Concentrate 3X to 5X feed TDS
 Concentrate flow 20% to 50% feed
 Sewer system to WWTP
 Deep well injection
 Evaporation ponds, playas
 Concentrated for zero-discharge
 Beneficial uses, land application
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LIVINGSTON ASSOCIATES, P.C.
Consulting Engineers
RO Equipment
Pre-engineered “skid” mounted incl.
pumps, pre-filters, chem feed, RO array
and controls
 For small systems from 15,000 gpd to
around 500,000 gpd
 Can be containerized or placed in a
building
 Modular for expansion
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LIVINGSTON ASSOCIATES, P.C.
Consulting Engineers
Relative Desalination Costs vs. Plant Capacity
(AWWA)
1.8
1.6
Unit Capital Cost
Unit O&M Cost
1.4
Cost Factor
1.2
1
0.8
0.6
0.4
0.2
0
1
5
10
Plant Capacity Factor
LIVINGSTON ASSOCIATES, P.C.
Consulting Engineers
20
40
O&M Cost
Power
 Labor
 Membranes
 Chemicals

10% to >50%
80% to <15%
<15% to 25%
<10% to >25%
Concentrate disposal
 Higher TDS, greater O&M
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LIVINGSTON ASSOCIATES, P.C.
Consulting Engineers
Desalination Cost Considerations
Target BW in lower TDS range (<5,000)
 Maximize recovery, utilize scale inhibitor
 Maximize blending potential, integrate
 Evaporate or land apply concentrate
 Use shallow wells near roads and power
 Gravity flow delivery system, exist route
 Use economies of scale, regional
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LIVINGSTON ASSOCIATES, P.C.
Consulting Engineers
BGW Quality Data Needed
TDS
 Conductivity
 pH
 Temp
 Major Cations/Anions
 Fe/Mn/Al/Si
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LIVINGSTON ASSOCIATES, P.C.
Consulting Engineers
Possible Strategies
ID potential users, small and large
 Evaluate opportunity for Regional
supply where possible
 Characterize BW resources within a
practical radius, power and routes
 Rank based on quality, yield, volume
 Perform RO pilot study for costing
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LIVINGSTON ASSOCIATES, P.C.
Consulting Engineers
Ft. Stockton, Texas
6 MGD RO Plant (3 MGD blend)
 TDS
1600
800 mg/L
 Sulfates
430
215 mg/L
 Hardness
600
300 mg/L
 Recovery
80%,
brine to WWTP
 Cost
= $0.30/kGal (blended)
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LIVINGSTON ASSOCIATES, P.C.
Consulting Engineers
Ft. Stockton 6 MGD RO
LIVINGSTON ASSOCIATES, P.C.
Consulting Engineers
WSMR Stallion Site EDR
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150,000 GPD
Feed TDS 3,600 ppm
Product TDS 500 ppm
Recovery 65%
Costs $2.00 per Kgal
Brine evaporated in
pond
LIVINGSTON ASSOCIATES, P.C.
Consulting Engineers
Alamogordo, NM
6 MGD RO Plant; expand to 13 MGD.
 TDS of GW 2,200 mg/L to 800 mg/L
 Blend 60% RO to 40% GW
 Recovery approx. 84%, brine to evap.
 Capital Cost = $8 M (plant/pond)
 Delivered Cost = $0.65/kGal
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LIVINGSTON ASSOCIATES, P.C.
Consulting Engineers
Gallup (White Cliffs)
15,000 GPD
 TDS*
 Recovery
 Capital Cost
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RO Plant
3,000
150 mg/L
85%,
brine to WWTP
= $50,000
* - varies
LIVINGSTON ASSOCIATES, P.C.
Consulting Engineers
Questions?
LIVINGSTON ASSOCIATES, P.C.
Consulting Engineers