SEAWATER AND VARIABLE SALINITY DESALINATION and...Trooper Smith, P.E.* and Jason Cocklin, P.E.** Florida Section AWWA Conference November 2018 SEAWATER AND VARIABLE SALINITY DESALINATION
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Trooper Smith, P.E.* and Jason Cocklin, P.E.** Florida Section AWWA Conference November 2018 SEAWATER AND VARIABLE SALINITY DESALINATION Optimization of Drought-Proof Water Supplies *FL, GA, NC, SC, TN, AL, TX **NC, TX
• Supply Strategy for Stakeholders and Large Volume Users
• Feasibility Study: NF for Brackish Groundwater Desalination
Presenter
Presentation Notes
Intro to water supplies; This explains WHY alternative water supplies, specifically drought proof and drought resistant supplies, are important for the Coastal Bend & Texas. 2. Feasibility Study addressing opportunities to leverage available water supplies for an optimized water supply strategy. 3. Supply Strategy from the perspective of large volume users as “water insurance” and establishing rate classifications to help fund desal projects. 4. Feasibility study addressing opportunities to optimize an existing brackish groundwater desal process.
Presenter
Presentation Notes
Current drought map – Nov 2018 August 2018 (4 months ago) the map looked a lot different. Surface water supplies change quickly. There is a strong need/desire to incorporate alternative water supplies to supplement existing surface water supplies.
• Drought-Contingent Supplies• Surface Water – Lakes and Rivers
• Drought-Resistant Supplies• Groundwater – Fresh and Brackish
• Reuse
• Drought-Proof Supplies• Seawater
WATER SUPPLIES AND DROUGHT
Water in the Texas Coastal Bend
Source: City of Corpus Christi
Presenter
Presentation Notes
Dependent on Traditional Surface Water Desal plants – Carlsbad (CA, 50 MGD), Tampa Bay (FL, 25 MGD), and Santa Barbara (CA – previously moth-balled but now producing 3 MGD) CITY WATER STRATEGIES – CONSERVATION, REUSE, DESALINATION Corpus Surface Water Supplies – Frio (Choke Canyon), Nueces (Lake Corpus Christi), Colorado River, Navidad (Lake Texana) 1 AFY decrease per year because of “decrease in yield due to sedimentation” Positive outlook of the City of Corpus Christi’s water supply system Mary Rhodes Phase II project However, in spite of the City’s demonstrated proactive approach, its current water supply is all based on surface water resources. The Corpus Christi region understands the need to diversify and supplement its water supply portfolio to ensure a reliable water supply. Industry (including 15% of the nation’s refining capacity) in particular needs the assurance that their businesses will not be impaired due to insufficient or unreliable water supplies.
Well Positioned for Desalination
Prospective Activity SummaryCorpus Christi Regional
Talking Points – 1. Regional Water Supply and Distribution, 2. Industrial demand and investment drive development. 50% of CC water feeds industry. Industrial demand growth 20 to 55 mgd in next 7 years. With the magnitude of the industrial presence and natural resources in the Coastal Bend, Corpus Christi is uniquely positioned for development of a desalination project. Existing Industries: LyondellBasell, Flint Hills, Citgo, Valero, OxyChem, Chemours/DuPont, Celanese, Exxon, etc. This slide will serve to: Discuss the knowledge we have gained about industrial water use and projected growth; illustrate how industrial activity is not confined to one specific are in the region but rather distributed throughout; This distribution presents both a challenge and an opportunity with regards to siting of a desalination facility. TM1 finding/recommendation: identify potential customers and determine potential demands early in the project.
US BUREAU OF RECLAMATION PARTNERSHIPS
Reclamation Funding Opportunities
• WaterSMART• WIIN Act• Title XVI
Presenter
Presentation Notes
The two feasibility studies we will discuss were partially funded through partnerships with Reclamation. 20% of the VSD Project and 50% of the North Alamo Project. Reclamation is interested and highly invested in research around conservation, optimization, and alternative water supplies. Brackish Groundwater National Desalination Research Facility (BGNDRF – called “berg-en-dorf” by the staff) Established in 2007. Research & pilot facility for Brackish Groundwater Desal and VSD.
1) Dissolved Air Flotation (DAF) – Targeting Harmful Algal Blooms
2) Micro- and Ultra-Filtration Membranes for Pre-treatment
3) Variable Salinity Desalination
VSD Study – Evaluation Objectives
Red Tide Event in Corpus Christi Bay in 1986 (Photo courtesy of Dr. Wesley Tunnel, HarteResearch Institute for Gulf of Mexico Studies at Texas A&M University – Corpus Christi).
Presenter
Presentation Notes
In-depth project review – Variable Salinity Desalination feasibility study and pilot protocol development. Partnership with US Bureau of Reclamation (Reclamation) – 20% grant funding Three key objectives for the study and pilot DAF for pretreatment (red tide, brown tide, TSS & turbidity spikes) MF and UF for membrane filtration ahead of the RO (impacts of performance on RO units……flux rates, fouling, and energy) VSD evaluation and optimization
Intro to Variable Salinity Desalination (VSD)
• Leveraging Local Resources for Process Optimization
• Development of Lower Salinity Sources• Brackish groundwater (BGW)
• Treated Effluent (Reuse)
• Energy cost savings / Economic Breakpoint
Presenter
Presentation Notes
VSD Objective - Determine the cost savings associated with reducing the feed water salinity by blending with locally available brackish groundwater (or other low salinity sources) and determination of the economical breakpoint between brackish groundwater development and energy cost savings by salinity reduction.
Water Supply Planning State Regional Local Key Issues
Seawater Desalination
Studies
Texas SWD Initiative
Feasibility Studies
Pilot Plant Studies
Other Studies Examples Key Issues
Brackish Ground-water
CC Consultant
Report
TWDB BGW Database
NGWA Prospective Key Issues
Variable Salinity Desalination Key Issues
Desalination Technologies
Source Water
Desal Methods Intakes Pre-
treatmentWaste & Energy
Mgmt Key Issues
ASR CCASRCD ASR & Desal ASR in Texas Examples Regulations Key Issues
Alternative Energy Sources Wave Geo-thermal Wind Energy Solar Fuel Cell Key Issues
Regulatory/ Permitting Local State Federal Key Issues
Research and Documentation Approach
Presenter
Presentation Notes
Very busy slide, no need to focus on the details here. �High level message – we looked at 8 areas of interest and reviewed over 60 papers, articles, project reports, and studies for each area. Key issues were derived from each area of interest and these lessons learned were applied in TMs 2, 3, and 4. Example: Seawater Desalination Studies > Brownsville Desal Pilot on Ship Channel > Turbidity/TSS Spikes > Overwhelm Pretreatment of Pilot
Impacts of Inner Harbor Activities
Google Earth Image
Presenter
Presentation Notes
Previous seawater desal pilot in Texas (Brownsville Ship Channel) experienced unanticipated impacts due to ship traffic. Lesson learned from Brownsville – turbidity spikes over 2,750 NTU caused by shipping traffic in the Brownsville Ship Channel completely overwhelmed membrane filtration. So we look at satellite imagery over time and then conducted field testing
• Turbidity ( < 10 NTU)
• TSS ( < 20 mg/L)
• Settleability Testing
Impacts of Harbor Activities
Presenter
Presentation Notes
Field Turbidimeter = LaMotte 2020we Handheld Turbidimeter (can measure up to 4,000NTU) Settleability Testing – Determination of the settling rate of TSS particles in a settleability column. Results were inconclusive because of very low TSS concentrations. Corpus Christi Inner Harbor - Deeper and wider than Brownsville Ship Channel
Sampling and Raw Water Quality
Presenter
Presentation Notes
Siting Area of Emphasis #1 – Seawater Quality 30 meter depth would be ideal…..but Bay depth ranged from 10-12 feet with exception of the ship channel (40-45 feet). 12 miles off shore – not quite 30m (81ft). Here we showcase our work and knowledge gained with regards to siting in the region: TM1 findings: water quality testing of multiple sites; need to understand harmful algal blooms potential The Sampler = VAN DORN SAMPLER The weight = “the messenger” Collected samples at depths which were representative of possible intake locations in the water column specific to each sampling site. BOTTOM DEPTH – 12 Miles offshore = 81 feet
Source Water Characterization
Grab Sample
Presenter
Presentation Notes
Tested for 51 water quality parameters. Example of TCEQ Surface Water Quality Monitoring Station Data. Long-term. (30 years of data at most locations) �Grab sample = snapshot in time = verification of SWQMS data. FNI Tested for algae, alkalinity, aluminum, arsenic, barium, boron, bromide, calcium, carbon dioxide, cesium, chloride, chromium, fecal coliform, total coliform, color, copper, DOC, enterococci, DO, DO sat, pH, fluoride, total hardness, Heterotrophic Plate Count (HPC), Iron (dissolved), Total Iron, total lead, magnesium, manganese, mercury, nitrate, ammonia, oil and grease (n-hexane), oxidation reduction potential (ORP), Total Phosphorus, potassium, salinity, Total colloidal silica (unreactive), dissolved silica (reactive), silt density index (SDI), sodium, conductivity, strontium, sulfate, temperature, tin, TDS, TOC, TSS, Turbidity, Zinc. Back to 1970s….TCEQ Sampling stations (mostly) record: conductance, salinity, TOC, chloride, sulfate, and water level.
• Design Criteria
• Process and Equipment Selection
• QA/QC plan
• Planning and Regulatory Requirements
VSD Report - Technical Criteria
Process Flow Diagram100% Seawater
Fine Screens
Feed Tank
DAF Disk Filters UF
MF
UVDisinfection
BreakTank
CartridgeFilters
BreakTank
RO Vessels (2)
Permeate(40% to
50%)Energy Recovery
Device
RO Vessel
Concentrate Disposal
100%Seawater
Presenter
Presentation Notes
Black arrows = process stream Purple arrows = waste stream DAF = Dissolved Air Flotation (Addressing TSS, Oils & Grease, harmful algal blooms) Reverse Osmosis = Single Pass. Residual pressure energy in the concentrate from two RO vessels helps to pressurize feedwater for the third vessel in an isobaric pressure exchanger (Energy Recovery Device) 40% to 45% recovery can be expected. Full scale example – to produce 10MGD of product water, you have 25 MGD of raw water and 15 MGD of concentrate.
Process Flow DiagramVariable Salinity Desalination
Fine Screens
Feed Tank
DAF Disk Filters UF
MF
UVDisinfection
BreakTank
CartridgeFilters
BlendTank
RO Vessels (2)
Permeate(50% to
75%) RO Vessel
Concentrate Disposal
Feed Tank
CartridgeFilters
BGW
Seawater
Presenter
Presentation Notes
Lower concentration of TDS to the RO vessels means we can have a 2-stage system (2:1) array. Still single pass (permeate only goes through RO membrane one time), but additional recoveries are gained by taking concentrate from first stage and running it through second stage RO vessel. Depending on salinity of blended feedwater, can get 50% recovery in first stage and 50% recovery in second stage (second stage is ½ the flow rate of the first) and an overall recovery of 75%. On a current groundwater desalination project, we are implementing a concentrate recycle stream to increase our recoveries to 85%.
PERFORMANCE PROJECTIONS OF FIRST STAGE VSD
Project HighlightDrought-Proof Water for Industries
City of Corpus Christi and
Port Industries of Corpus Christi (PiCC)
Non-Curtailment Water Agreement
• City Drought Contingency Plan included curtailment of water supplied to industries (LVU).
• Industries are willing to pay a surcharge if the City will guarantee no curtailment.
• City will develop drought-proof water supply to meet the additional demand requirement.
• Additional Initial Capital Cost: $427,200 • Energy savings: $108,100/yr.
Presenter
Presentation Notes
If applied to all 4 NAWSC BGW Facilities: 600,000 gpd increase in production ~4 year break-even on additional capital required for retrofit
Trooper Smith, P.E.*
and
Jason Cocklin, P.E.**
Florida Section AWWA Conference
November 2018
*FL, GA, NC, SC, TN, AL, TX**NC, TX
Presenter
Presentation Notes
Despite the hurdles, desalination is a proven globally with just under 23 billion gallons per day installed capacity. What was cost prohibitive or technically challenging in the past is becoming the reality of the global water market. In the right circumstances, VSD is one of the innovations which can make desalination easily attainable to meet a critical demand or supplement a less-reliable source.
