Desalination and Water Reuse: Finding the right solutions for Sydney s water supply September 17, 2005
Agenda Quantifying Sydney s Water Problem What are the options for creating new sources of water What steps should Sydney take to ensure a sustainable supply of water?
Today s observation It is appropriate for coastal cities to develop plans to rapidly deploy desalination capacity in response to protracted and severe water shortage However, desalination, like many water supply alternatives requires significant energy. Therefore, when expanding Sydney s supply we must account for and value the energy input
Quantifying Sydney s Water Problem Supply 600 GL of secure yield per annum 660 GL demand per year in 2004 800 GL demand projected for 2039 Flow restoration (Hawkesbury-Nepean) Release of 50-150 GL per annum* Water Deficit in 2039 250 350 GL per annum Source DIPNR (* excluding estimates for flow restoration)
Proposed solutions Access Deep Storage - 2006 Yield: 30 GL Capital cost: $106 M Power: < 0.14 kwh/m 3
Proposed solutions Transfers from Shoalhaven 2009 (Stage 1) Yield: 110 GL per annum Capital cost: $ 430 M Power: 1.9 kwh/m 3
Desalination for Sydney? Possibilities Kurnell Peninsular Tentative Production Targets of 36 to 180 GLA Energy Requirements* 4.54 kwh/m 3 *Sydney Water Web-site
What does desalination offer? Drought proof supply Example - UAE (pop. 2.6 M) Desal yield 1160 GLA Alternative to surface water diversions Kuwait (International) Transfers: 273 GLA Desal: 539 GLA Spain (Internal) Transfers (Ebro) 1060 GLA Desal: 352 GLA 23% total (40% mainland) to avoid additional transfers Desalination is an expanding market Capacity pre 2005-11,200 GLA Ten Year Projection (2005-2015) 11,300 GLA
Desalination Techniques? Thermal techniques (% installed capacity) MSF: Multi Stage Flash distillation (40%) Typical plant 20 600 MLD MED: Multiple Effect Distillation (4%) Typical plant 2 20 MLD MVC: Mechanical Vapor Compression (4%) Typical plant 0.5 10 MLD Membrane Techniques RO: Reverse Osmosis (43%) Typical plant 0.1 100 MLD ED & EDR: Electrodialysis (Reverse) (5%) Typical plant 1 20 MLD
Thermal Desalination Taweelah, UAE 710 MW Power plant 227,000 m 3 /day Multi Stage Flash Source: International Desalting Association
Reverse Osmosis Desalination Tampa, Florida USA Feed water Gulf of Mexico 26,000 28,000 mg/l Co-located with power plant
Gulf Installations MSF 2938 GLA : RO 127 GLA Source: Wagnick 2000
Mediterranean Installations RO 485 GLA : MSF 226 GLA Source: Wagnick 2000
RO Membrane Structure Polyamide barrier layer Polysulfone support layer
Membrane RO Element Structure
RO Pressurized Vessel Structure Feed Permeate Seal Concentrate Permeate collection tube Permeate tube coupling Pressure vessel
Reverse Osmosis Key Design Concepts Water Produced defined by flux (J) Volume of water per unit area per unit time J = P - π µ(r m + R f ) Pressure across the membrane ( P) Achieved by feed pump Osmotic pressure (π) increases with salinity and temperature Viscosity (m) decrease with temperature Resistance (R m +R f ) - Varies as a function of flux and recovery precipitation of sparingly soluble salts (ph & anti-scalants) - biological & colloidal material
Components of a RO System Chemical Conditioning Acid Scale Inhibitor Seawater Intake Pretreatment RO Chlorination Stabilization Storage & Distribution Screens Beach wells In-Line Coagulation Direct Filtration MF/UF Cartridge Filtration Brine Cleaning Waste Waste
Membrane System are Modular
Comparative Summary MSF RO Max Temperature ( o C) Feed Quality (mg/l) Water Quality (mg/l) Unit Size (m 3 /day) Size limitation Recovery (%) Energy (kwh/m 3 ) 110 33 000 50,000 < 20 76,000 Tubes 10 40 10-13 Ambient (< 40) < 33 000 300-500 18,600 Vessels/Pipework 40 50 3.9 5.0
Historical Cost of MSF $US 0.70/m 3 Source: Desalination Markets: Global Water Intelligence
Historical Cost of RO Ashkelon $US 0.65/m 3 Source: Desalination Markets: Global Water Intelligence
Other Solutions Demand Management BASIX targets 40% reduction Reduce additional demand in 2039 by 80 GLA Reuse Water reuse less than 3% Acknowledge the value of water (particularly energy) Recycling for industry Botany-Mascot-Kurnell 10% of potable demand Sydney Water Estimates at 70MLD max
Efficient Water Management Restoration of Environmental Flows
Efficient Water Management Substitution for potable water in irrigation and agriculture applications
Substitution for potable water in industrial and chemical processing applications West Basin Municipal Water District Anchor customer scheme up to 200 MLD by 2015
Substitution for potable water in Semi-conductor manufacturing
Drought proof surface water supplies Upper Occoquan Sewage Authority (UOSA) Regional Water Reclamation Plant (200 ML/day)
Maintain Groundwater Levels Recharge Basins Miller Basin Seawater Intrusion Barrier GWR Pipeline Kraemer Basin Orange County Ground Water Replenishment System 260 MLD for indirect potable reuse
History of indirect potable reuse and high grade industrial reuse First Use of Reverse Osmosis Water Factory 21 First Use of Ozone and GAC in Water Reclamation West Basin First On-line Monitoring Techniques for MF & RO Scottsdale Pretoria San Diego Aqua 2000 Luggage Point, Brisbane GWR System 1968 1976 1978 1979 1990 1994 1996 1997 1999 2000 2002 2005 Windhoek Cape Town UOSA Water Factory 21, USA Gwinnett County Flow Augmentation Singapore NEWater World s First Direct Potable Reuse Application First Surface Water Augmentation First Demonstration of Microfiltration for GWR System Comprehensive Health Effects Study
Water Recycling Using Membranes Secondary Effluent Contaminants Turbidity REJECT REJECT Inorganics Virus Microfiltration Reverse Osmosis UV / Advanced Oxidation High Grade Water Bacteria Protozoa Organics Removal Turbidity Bacteria Protozoa Virus Removal Turbidity Inorganics Virus Bacteria Protozoa Removal Virus Bacteria Protozoa Organics NaOH or Ca(OH) 2 + CO 2 Increase ph Raise LSI Organics
What are the main health concerns in recycling for supplementing drinking water supplies? Acute Concern - Microbial pathogens Approach - Rigorous testing of multiple barriers (log removal) Assessment Demonstrate specified log removal of indicator organisms and compare with traditional water supplies Regulation Daily check of water quality. On-line check of membrane integrity Chronic Concern dissolved organics Approach & Assessment Develop data base (occurrence & concentration) Risk Assessment (CFA using CPF for IPU & raw water) Live animal testing & sentinel monitoring Regulation Comply with drinking water guidelines + surrogate parameter (e.g. TOC)
Targets for Acute Effects 0.02 0.08 µm 0.3 2 µm Virus Somatic Coliphage Male-specific Coliphage Enterovirus Bacteria Heterotrophic plate counts Total Coliform Faecal Coliform Enterococci Clostridium perfringens 3 15 µm Protozoa Cryptosporidium Giardia
Log removal Microbial removal & inactivation efficiency is expressed in terms of log reduction 1 log reduction (10 1 ) = 90% removal or inactivation 2 log reduction (10 2 ) = 99% removal or inactivation 3 log reduction (10 3 ) = 99.9% removal or inactivation 4 log reduction (10 4 ) = 99.99% removal or inactivation
Low End Removal efficiency of unit processes Virus Bacteria Protozoa Effluent Conc. (organisms/100ml) 1 x 10 2 1 x 10 7 1 x 10 2 MF/UF 1 6 6 RO 4 4 4 UV 4 4 4 Ct 1 - - Min Process Efficiency (Log removal) Product Conc. (organisms/100ml) 10 14 14 1 x 10-8 1 x 10-7 1 x 10-12
The risk of exposure & infection from recycled water is significantly lower than some potable water supplies Daily Exposure (2 L per day) Virus Bacteria Protozoa Drinking Water* 0.008 0.116 0.132 IPU Recycled 2 x 10-7 2 x 10-6 2 x 10-11 Probability of infection Drinking Water 4.9 x 10-3 2.7 x 10-4 2.6 x 10-3 Acceptable Risk (Drinking Water) Probability of Infection (Recycled) *Rose et al. 1996 1 x 10-4 1 x 10-4 1 x 10-4 1.2 x 10-9 4.7 x 10-10 3.9x10-14
What about the risk from pharmaceuticals and other organics? Ibuprofen C 13 H 18 O 2. naproxen C 14 H 14 O 3 Ibuprofen naproxen
We can determine the presence of wastewater organics by looking for indicator compounds Wastewater indicators compounds Generally the most concentrated organics in wastewater (present at micrograms per litre) The compounds are the residuals from soaps and detergents 4 classes of indicators Alkylphenol carboxylates (APEC) Ethylenediamine tetraacetic acid (EDTA) Nitrolotriacetic acid (NTA) Naphthalene dicarboxylic acid (NDC)
The size and shape of indicators is comparable to pharmaceuticals EDTA - ethylenediaminetetraacetic acid C 10 H 16 N 2 O 8
These compounds are removed from wastewater by the reverse osmosis membranes Santa Ana River 1 Feed Reclaimed 2 Product Organics ( (µg/l) 100 10 1 0.1 ND (Samples) 13 5 5 EDTA NTA NDC Total APEC 1. Sampled downstream of Prado wetlands once every 3 months 2. Sampled in RO permeate from WF21 Membrane demonstration once every three months
Pharmaceuticals are at much lower concentrations and are also removed by RO Concentration (ng/l) Constituent Influent RO Product UV/H 2 O 2 Product Ibuprofen 2300 ND ND Naproxen 1800 ND ND Gemfibrozil 4600 ND ND Diclofenec 200 ND ND Ketoprofen 47 ND ND Data courtesy of S. Deshmukh, OCWD (2003)
Recycled water was chosen from a list of four alternative water supplies for Orange County California Seawater Intrusion Barrier Recharge Basins Imported water from Colorado River Imported Water from northern California Seawater Desalination Indirect Potable Water Recycling
The decision was based on many factors including the lower energy requirements for water delivery 3.5 4.0 kwh/m 3 2.62 1.82 1.19 Desal State Water Project Colorado River GWRS
Annual energy savings in California Recycling versus imported water* Annual Power Savings 1 million barrels of oil (50% of average tanker) $67 million US/ year Based on the energy saved by implementing phase 1 of the GWR System in lieu of additional transfers from northern California
Other benefits of water recylcing include reduced or avoided impacts of Water Transfers Mono Lake in the Sierra Nevada ranges was protected from water transfers in the 1990 s
Impacts of Water Transfers from Lake Owens to City of Los Angeles Dust storms in lake Owens California. Prior to water transfers lake Owens in the Sierras provided water to a thriving farming community
Desalination and Recycling in Singapore play a role in safeguarding Singapore s water supplies De Desalination plant Ulu Pandan NEWater
Desalination and Recycling in Singapore
Desalination and Recycling in Singapore
Securing Singapore s Water Supplies 1996 Projection 6 desalination plants Tuas (x2) Changi Pulau Tekong Jurong Island Pulau Busing 2005 Reality 4 NEWater plants Bedok Kranji Seletar Ulu Pandan 1 Desalination Plant Tuas
Recycling Values Finite Resources Aluminium Cans 14 kwh/kg 1 kwh/kg
Conclusions Desalination is an alternative source of water The market is expanding However, Sydney needs to make sure that measures like conservation & reuse are implemented prior to deploying desal to value the energy embodied in the system
What should we do? Continue to advocate conservation Support council on local projects Stormwater harvesting Localised non-potable recycling Expanded use of grey water and point of use Be open to all forms of recycling Encourage government to investigate indirect potable recycling as thoroughly as desalination