brown douglas presentation

8/2/2019 Brown Douglas Presentation

1/36

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


2/36

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


3/36

Southeastern Denver Has Limited Surface WaterSupplies and Relies on Imported Water or DeepNon-tributary Groundwater


4/36

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


5/36

1 mile


6/36

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


7/36

ECCV Water Well Production will Decrease50% in 10 Years Requiring 377 New Wells


8/36

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


9/36


10/36

Renewable Groundwater from Northern Project

Being Blended with Other District Supplies


11/36

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


12/36

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


13/36

ECCV Northern

Water System

47 MGD UltimateCapacity


14/36

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


15/36

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


16/36

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


17/36

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


18/36

Brackish RO Concentrate Typically DoesNot Exhibit Acute or Chronic Toxicity


19/36

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


20/36

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


21/36


22/36

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


23/36

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


24/36

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


25/36

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


26/36

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


27/36

Passive Evaporation Basins RequireExtensive Land Even in Southwest Desert


28/36

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


29/36

A Low-Cost Solar Basin with an Air SpargerCan Increase Evaporation Rates

Gravel Diffuser Layer

Air Distribution Grid

RO Concentrate

Basin Liners


30/36

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


31/36

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


32/36

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


33/36

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


34/36

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


35/36


36/36

Thank you, and Time for Questions

Doug Brown 303-383-2316 direct

303-915-3042 cell

[email protected]

brown douglas presentation

Documents