Brown Douglas Presentation
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Transcript of Brown Douglas Presentation
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Kipp Scott, East Cherry Creek Valley Water and Sanitation DistrictDoug Brown, P.E. CDM
Navigating the Regulatory and PermittingHurdles for Concentrate Discharge
Multi-State Salinity Coalition
February 18, 2011
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Presentation Outline
Background on ECCV Project
Overview of Brackish Water Reverse Osmosis (RO)
Treatment Factors Affecting Residuals Disposal for Inland
Facilities
Disposal Alternatives and Regulatory Issues
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Southeastern Denver Has Limited Surface WaterSupplies and Relies on Imported Water or DeepNon-tributary Groundwater
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ECCV initially relied on
dozens of non-tributary
groundwater for its
water supply
The Arapahoe and
Laramie/Fox Hills
aquifers have less than
300 mg/L TDS and 100
mg/L hardness
Existing ECCV Water Supply Is BeingDepleted and Is Not Renewable
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1 mile
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Non-potable Irrigation
with Reclaimed Water
Denver Treated Water
Block Water Rates
Conservation Incentives
Reduced Demand 30%
from 1995
ECCV Is Diversifying and Conserving ItsWater Supply
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ECCV Water Well Production will Decrease50% in 10 Years Requiring 377 New Wells
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Beebe Draw alluvial wells
Phase I water rights 70Ranch
Phase II water rights Barr& Milton shares
Phase I facilities Well field Pump Stations Waterline
The Northern Project
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Renewable Groundwater from Northern Project
Being Blended with Other District Supplies
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Water Treatment Planning Objectives
Consistent quality product Free of objectionable taste and odors
Water quality meets end user requirements
Consistently meets drinking water standards
Specific water quality targets Total Dissolved Solids < 300 mg/L
Total Hardness < 100 mg/L
Firm treatment and pumping capacity to meet peak
demands
Reliable service
Reasonable operating costs
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Selection of Water Treatment Process
High hardness and TDS required blending or
reduction of these compounds
Blending is not a long-term solution Lack of long-term blending sources
Reverse Osmosis selected Most cost-effective for TDS
Only effective process to consistently meet water
quality goals Also eliminates almost all other potential
contaminants from effluent dominated sources
The challenge is the disposal of the concentrate
stream (brine) from the treatment process
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ECCV Northern
Water System
47 MGD UltimateCapacity
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Overview of RO Process and ConcentrateDisposal
Typical low pressure RO operating at 85%
recovery treating GW with 700 mg/L TDS &
300 mg/L hardness
6.7 MGD of permeateblended with 3.3 MGD
of UV treated well
water
1.2 MGD of
concentrate with 5000
mg/L TDS
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RO Concentrate Disposal Options
1. Discharge to Sanitary Sewer System or POTW
Discharge
2. Surface Water Discharge through NPDES permita. navigable waters
b. irrigation ditches
3. Deep Well Injection
4. Beneficial Uses5. Zero Liquid Discharge Using:
a. thermal/mechanical evaporation systems
b. enhanced evaporation system
c. passive evaporation basins
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Brine Concentration & Volume Vs. Recovery
50 60 70 80 90 100
50
45
40
35
30
25
20
15
10
5
0
R
OConcentrateTDSppt
(assume1000mg/Lraw
water)
Recovery Percent
50
45
40
35
30
25
20
15
10
5
0
ConcentrateVolum
e%
Mass of Salt Discharged is Constant
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Potential Impacts of RO Concentrate onWastewater Treatment Plant
1. Decreased hydraulic residence time and
potential impacts on effluent BOD and TSS
2. Increase in effluent TDS
3. Potential Increase in Elements such as
Radionuclides, heavy metals, nitrates
4. Potential Inhibitory Effect on Treatment Biology
at High % of Concentrate5. Potential Impact on WET Tests
6. Potential Impact on Equipment Corrosion
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Brackish RO Concentrate Typically DoesNot Exhibit Acute or Chronic Toxicity
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Wastewater System ConcentrateManagement Options
1. Blend Concentrate with the Treatment Plant
Effluent
2. Send Concentrate Through System During Off-
Peak Times
3. Pre-treat Concentrate for Specific Contaminants
of Concern: Heavy Metals, Nitrates, Radionuclides
4. Develop a Salt Balance for the Basin toDemonstrate No Impact on Total Salt Discharge
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River
Distribution
System
Sanitary
Sewer
Flow
Irrigation
Return
Flow
10-mgd
Existing
Brackish
Wells
@ 1,000
mg/L TDS
POTW
RO
System
9.3 mgd
250 mg/L
10 tons/day
40
tons/day 2.5 mgd
7.5
mgd
0.8 mgd @ 10,000 mg/L = 30 tons/day of salt
6.8 mgd
Adding a RO System to an Existing WaterSupply Results in a Neutral Salt Balance
Salt
M
Blend
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Summary of Potential RO Impacts onWastewater Treatment Plants
Minimal Performance and Water Quality Impacts on
Wastewater Treatment Plants Receiving a Small
Percentage of RO Concentrate
Potential Hydraulic Impacts if RO Concentrate is aSignificant Percentage of the Wastewater Treatment
Flow
The Increase in Effluent TDS from a Brackish RO
Concentrate Discharge Can Have an Impact onEffluent Reuse Options
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Surface Water Discharge Options
1. Discharge to surface water
2. Secondary Recovery (Brine Minimization) to
reduce concentrate volume to ~ 3% of RO flow Enhanced evaporation and landfill of dry solids
Use of blowers
Pond sizing based on annual volume
Deep well disposal
Initial stage w/o secondary recovery
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Discharge to Surface Water TypicallyAvoided Since Daily Salt Discharge from aBrackish RO Project is Significant
Daily Salt Discharge Tons / Day
0
10
20
30
40
50
60
70
80
90
100
10 mgd BWRO
@2000 mg/LColorado Road
Deicing
10 mgd
Municipal
WWTP
10 mgd Water
Softener @ 400 mg/L
As CaCO3
Daily Salt Discharge Tons / Day
Courtesy of NYLCV
Approx. 2400 tons of Road Salt
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NPDES Permit Can Be Based on DischargeStandards or Non-Degradation Criteria
TDS typically is not a discharge standard because
wastewater treatment plant cant remove it
Nitrate, metals, radionuclides are concentrated
by RO and can exceed discharge standards
ECCV discharge permit to irrigation ditch was
based on non-degradation of groundwater and
controlled by Fluoride, uranium and gross alpha Acute and chronic toxicity discharge standards
can be impacted by common ion concentration
and ratios
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Zero Liquid Discharge (ZLD) Options
Thermal/mechanical evaporation
systems: vapor recompression, spray
dryers, crystallizers
Photo courtesy GE Infrastructure
Low tech
evaporation
processes: passive
solar evaporation
basins, enhancedevaporation basins,
misters, undulating
film evaporators
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Passive Evaporation Basins RequireExtensive Land Even in Southwest Desert
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High Recovery RO Using both WACand SAC
Removes Ions That Form Scale
Calcium
Magnesium
Barium
Strontium
Iron
Manganese
Aluminum
Strong Acid
Cation IX
Weak Acid
Cation IX
Reverse
Osmosis
Conc.
BrineConc.
Brine
Conc.
Brine
HardnessRemoval
PolyvalentCations
High pHSeparation
High Purity
Water
Ground
Water
Ambient pH RO Operation Controls Silica Scaling
Eliminates NaOH Feed
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A Low-Cost Solar Basin with an Air SpargerCan Increase Evaporation Rates
Gravel Diffuser Layer
Air Distribution Grid
RO Concentrate
Basin Liners
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Deep Wells Can Be Used for Final Disposalof Concentrated Brine
23 operating injection wells in Adams and Weld
Counties (47 permitted by the State O&G Div.)
ECCV well - EPA permit for a Class 1 well
Underground formations 9,000+ feet belowdrinking water aquifers and 1,400 ft. above
Rocky Mountain Arsenal wells
Estimated injection rate of 200 to 400 gpm
Estimated cost of $2,280,000 per completed well
+ pipeline from plant to well
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31
Brine Injected Below Potable
Water Aquifers
Injection wells include outer casing
and inner casing to create and
annular space that can bemonitored for leaks
Corrosion resistent materials
compatible with salty brines
Chemical stability of brines during
and after injection
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32
Secondary concentration of RO concentrate using brine minimization to 3%of flow treated to minimize water rights loss and # of deep disposal wells
Deep Well Disposal Option
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ECCV Phase 1 Low Pressure RO andBrine Minimization System
7.8 MGD Ground Water
700 mg/L TDS
6.6 MGD Permeate
50 mg/L TDS
LPRO @ 85%
Brine Minimization1.2 MGD Concentrate
4600 mg/L TDS
0.3 MGD Brine @
18,000 mg/L TDS
0.9 MGD Permeate
500 mg/L TDS
140 psi
High RecoveryRO @ 75%
10.8 MGD Blend
300 mg/L TDS
Pre-treatment
3.3 MGD By-Pass Blend
Residuals
Deep Well Injection
High pressure Injection Pump10,000 ft. Deep
Class I Injection Well
Acid
UV Disinfection
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Total Estimated ECCV ZLD O&M costsper 1,000 gallons of net water production
Secondary Recovery
and Landfill of Dry
Solids w/
Enahanced Evap.
Deep Well
Injection, No
Secondary
Recovery
Deep Well Injection,
With Secondary
Recovery
SecondaryConcentration
$0.58 N/A $0.58
Enhanced Evaporation
and Landfill of Dry
Solids
$1.74 N/A N/A
Deep Well Injection N/A $0.08 $0.02
Total ZLD O&M Cost $2.32 $0.08 $0.60
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Thank you, and Time for Questions
Doug Brown 303-383-2316 direct
303-915-3042 cell