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Affordable Desalination Collaboration Findings Related to Regulatory Criteria, Process and Costs for Seawater Desalination. Tom Seacord , P.E. ADC – Chairman of the Board of Directors. Goals of the ADC. Demonstrate affordable desalination using innovative technologies & processes
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Affordable Desalination Collaboration Findings Related to Regulatory Criteria, Process and Costs for Seawater Desalination Tom Seacord, P.E. ADC – Chairman of the Board of Directors
Goals of the ADC • Demonstrate affordable desalination using innovative technologies & processes • Create a body of data that can guide & benefit future designs • Educate the public to show that desalination is an affordable, viable source of fresh water
Zenon West Basin municipal water district Current and past members of the ADC have included agencies, consultants, and leading manufacturers AMIAD
ADC’s work has included three different phases • ADC 1: Demonstrating actual SWRO energy using conventional pretreatment and full-scale commercial technology (May 2005 - April 2006) • Funded by ADC members • ADC 2: Further demonstration using alternate pretreatment and RO membranes (Jan - Nov 2009) • Funded by Prop 50 and ADC members • ADC 3: Brackish RO concepts • Collier County, FL (June – Dec 2006) • Funded by TWDB and ADC members (Feb - Dec 2010)
ADC has proven that SWRO’s efficiency has improved significantly using off-the-shelf technology 13.0 13.0 49.1 49.1 16000 11.4 11.4 43.0 43.0 14000 ) ) 3 9.7 9.7 36.8 36.8 kgal 12000 hr/m hr/ - 8.1 8.1 30.7 30.7 - 10000 6.5 6.5 24.6 24.6 8000 Specific Power (kW-hr/AF) Specific Power (kW Specific Power (kW 4.9 4.9 18.4 18.4 6000 3.2 3.2 12.3 12.3 4000 1.6 1.6 6.1 6.1 2000 0 0 0 0 1970 1980 1990 2000 ADC 2006
ADC’s work has been widely referenced when defending desalination as a water supply alternative in California 6.5 26.4 8000 General ) ) Perception 3 4.9 18.4 kgal 6000 hr/m hr/ Expert's Perception - - 3.2 12.3 4000 Specific Power (kW-hr/AF) Specific Power (kW ADC 2006 Specific Power (kW ADC 2006 SWRO Process 1.6 6.1 2000 0 0 0 State Project Water Colorado Aqueduct Water SWRO
BackgroundCalifornia Water Supply & Treatment Costs $0.9 $0.9 $3.6 $3.6 $1,200 Public Perception ) ) kgal $0.8 $0.8 $3.0 $3.0 Expert Perception Brine Disposal From Inland Empire Area $1,000 3 $0.6 $0.6 $2.4 $2.4 $800 ADC 2006 Supply & Treatment Cost ($/AF) $0.4 $0.4 $1.8 $1.8 $600 Supply & Treatment Cost ($/m Prod. & Dist. Cost Supply & Treatment Cost ($/ $0.3 $0.3 $1.2 $1.2 $400 $0.1 $0.1 $0.6 $0.6 $200 $0 $0 $0 $0 $0 Recycled RO Seawater RO State Project Water Colorado Aqueduct Water Metropolitan Water District
ADC SWRO Plant Schematic 40 Foot Containerized 200-350 m3/day SWRO Pilot 1.8 kWh/m3 6.8 kWh/kgal 3 x 7 element 8” RO vessels F Product E Multi-Media Filter PX Boost Pump HP Pump G C D Holding Tank Supply Pump PX Reject Micron Filter A B H Intake pier Typical ADC Operating Conditions Seawater Return Seawater ROSA6.0 Projections SW30XLE-400, 7.2 gfd, 45% recovery, 60°F, 34,432 TDS feed, 0.85 Fouling
Test Parameters & Data Collection • Variables • Flux rates: 6, 7.5, 9 gfd • Recovery: 35, 42.5, 50% • Membrane Rejection: 99.5%-99.8% • Plant size: 10, 50 MGD • Data analysis • Power consumption • Feed pressure and membrane DP • ASTM normalized data • Feed quality • Permeate quality and Boron • NPV of capital costs vs. O&M (energy costs)
Cost Estimating Procedures • Net Present Value Analysis • Amortized capital costs • Project Life 30 years, 5% interest • Co-location • 10 MGD: Co-located with WWTP outfall, new open intake • 50 MGD: Co-located intake/outfall with power plant • Annual O&M • Power $0.08/kW-hr • Replacement of Membranes (CARR) • To maintain performance (energy & permeate quality)
50-MGD Conceptual Study • Pressure Center • Pump Center • Energy Recovery Center
10-MGD Conceptual Study • Dedicated Pumps/ERDs • Feed pump for every train • Energy recovery for every train
Initial Filtration Problems Red tide SDI < 5 Not exceeded 86% Turbidity < 0.1 Not exceeded 88% Raw Turb RO Feed Turb SDI Pretreatment 10 6 5 1 4 Silt Density Index Turbidity (NTU) 3 0.1 2 1 0.01 0 0 200 400 600 800 1000 1200 1400 1600 Run Time (hours)
PD Pump Selected for ADC High efficiency Pulsating flow Centrifugal Pumps Used for Larger Trains Low efficiency for small pumps Smooth flow Pressure Center Design May reduce power @ low flow rates 50 MGD Case Study 5.9 to 8.9 kWh/kgal 10 MGD Case Study 6.6 to 9.8 kWh/kgal SW30HR-380, 6 GFD @ 50% SW30XLE-400i, 9 GFD @ 50% SW30HR LE-400i, 6 GFD @ 50% Impact of Feed Pump - Scalability 12 2.5 2.3 10 2.0 8 Specific Power (kW-hr/m3) Specific Power (kW-hr/kgal) 2.3 6 2.0 4 1.8 2 0 0 0 2 4 6 8 10 Train Size (MGD)
6 GFD 7.5 GFD 9 GFD Permeate Quality - Boron • Flux = Boron • Recovery = Boron • Low energy membrane produced marginally acceptable boron • SW30HR-380 • 0.45 to 0.85 mg/L • SW30XLE-400i • 1.05 to 1.44 mg/L • SW30HR LE-400i • 0.45 to 0.85 mg/L 2.0 Boron < 1.45 mg/L 1.8 to comply with California standard 1.5 1.3 SW30XLE-400i Permeate Boron (mg/L) 1.0 0.8 0.5 0.3 0.0 35% 43% 50% Recovery
6 GFD 7.5 GFD 9 GFD Permeate Quality - Boron 2.0 Boron < 1.45 mg/L to comply with California standard 1.8 1.5 1.3 1.0 SW30HR-380 Permeate Boron (mg/L) 0.8 0.5 0.3 0.0 35% 43% 50% Recovery
6 GFD 7.5 GFD 9 GFD Permeate Quality - TDS • Flux = TDS • Recovery = TDS • Low energy membrane produced highest TDS • SW30HR-380 • 80 to 175 mg/L • SW30XLE-400i • 190 to 350 mg/L • SW30HR LE-400i • 95 to 295 mg/L 400 350 300 250 SW30XLE-400i Permeate TDS (mg/L) 200 150 100 50 0 35% 43% 50% Recovery
6 GFD 6 GFD 7.5 GFD 7.5 GFD 9 GFD 9 GFD Permeate Quality - TDS 400 400 350 350 300 300 250 250 SW30HR-380 Permeate TDS (mg/L) SW30HR LE-400i Permeate TDS (mg/L) 200 200 150 150 100 100 50 50 0 0 35% 43% 50% 35% 43% 50% Recovery Recovery
Treatment CostsEstimated Costs for 50-MGD SWRO WTP (SW30HR-380)
Treatment CostsEstimated Costs for 10-MGD SWRO WTP (SW30HR-380)
Conclusions • Flux & recovery impact permeate quality • Low energy SWRO membrane has lowest cost, but poorest permeate quality • Due to size and type of pump, 10 MGD plant less efficient • 10 MGD – 6.6 to 9.8 kWh/kgal • 50 MGD – 5.9 to 8.9 kWh/kgal • ADC’s design power by • 10 MGD – approx. 30% over industry perception • 50 MGD – approx. 40% over industry perception • Low = 5.98 kW-hr/kgal
Conclusions (cont.) • Recovery of 50% resulted in lowest NPV • Improving boron/TDS rejection results in higher energy use & treatment cost • SWROis competitive with other supply options in California • 10 MGD • $1,552 to $1,820/AF • 50 MGD • $794 to $966/AF
Recommendations • Data must be taken in context of raw water quality (i.e., temperature) • Designers must consider public values when establishing design water quality (i.e., boron) • Future Work • Pretreatment • Higher Recovery • Long Term Testing • Economy of Scale – Large Diameter Elements
ADC’s Publications & Outreach • Seacord, et al. 2006. Affordable Desalination Collaboration 2005 Results. Desalination & Water Reuse Quarterly. Vol. 16:2. • Seacord, et al. 2007. ADC 10 MGD Case Study. Proc. 2007 AMTA Annual Conf. • MacHarg, et al. 2008. ADC Baselines SWRO Performance. Desalination & Water Reuse Quarterly. Vol. 18:2. • Dundorf, et al. 2009. Optimizing Lower Energy Seawater Desalination. Proc. 2009 IDA World Congress. • AMTA Preconference Workshops • 2008, 2009, 2011