wfhc-DesalinationReport

Water for a Healthy Country

Desalination Options and their possible implementation in Western Australia

Potential Role for CSIRO Land and Water

Olga Barron

June 2006

Water for a Healthy Country

Desalination Options and their possible implementation in Western Australia

Potential Role for CSIRO Land and Water

Olga Barron

June 2006

The Water for a Healthy Country National Research Flagship is a research partnership between CSIRO, state and federal governments, private and public industry and other research providers.

The Flagship was established in 2003 as part of the CSIRO National Research Flagship Initiative.

© Commonwealth of Australia 2006 All rights reserved. This work is copyright. Apart from any use as permitted under the Copyright Act 1968, no part may be reproduced by any process without prior written permission from the Commonwealth.

Citation: Barron, O. (2006). Desalination Options and their possible implementation in Western Australia: Potential Role for CSIRO Land and Water. CSIRO: Water for a Healthy Country National Research Flagship, Canberra.

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Desalination Options WA Potential role for CLW

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Table of Contents

Introduction ......................................................................................................................... 3 1. Desalination processes and desalination cost.............................................................. 4 2. Renewable energy sources (RES) and desalination .................................................... 7 3. Latest developments in the desalination technologies ............................................... 10 4. Desalination in Australia ............................................................................................. 12 5. Conclusions: Potential CSIRO involvement in desalination programme

development in WA .................................................................................................... 14 6. References..................................................................................................... 18 Appendix 1: Desalination Technologies ............................................................................... 23 Appendix 2: Factors influencing the desalination cost ......................................................... 24 Appendix 3: Renewable energy sources and desalination................................................... 27 Appendix 4: Research activities in desalination ................................................................... 29 Appendix 5: Environmental impact assessment requirements for desalination plants in

ASEZ (from Dweiri and Badran, 2002) .......................................................... 32

List of Figures Figure 1: Categories of desalination processes (from MEDRC publications) ................. 4 Figure 2: Capital cost of reverse osmosis versus multistage flash (from Abou-

Rayan and Khaled, 2002) ................................................................................ 5 Figure 3: The relationship between the SWRO plant product cost (a) and capital

unit cost (b) and the plant capacity (from Hafez and El-Manharawy, 2002) .... 6 Figure 4: Comparison of water quality and water price for operation mode.................... 8 Figure 5: Potential use of various type of renewable energy in desalination process

(from MEDRC) ................................................................................................. 8 Figure 6: Effect of evolutionary and revolutionary technologies (USBR) ...................... 11 Figure 7: Action and Planning Window for Water Resources Development (Water

Corporation) ................................................................................................... 13

List of Tables Table 1: Energy use by various desalination processes (Water Corporation, 2000) ..... 6 Table 2: The effect of advanced technology on the RO process by improving

efficiency and lower costs, capacity of 5,000 m3/d (Glueckstern, 1999) .......... 7 Table 3: Capacity of natural energy resources in the World (from Belessiotis and

Delyannis, 2001) .............................................................................................. 9 Table 4: Recommended renewable energy – desalination technologies

combinations (Oldach, 2001) ........................................................................... 9


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Table 5: Range of product water cost produced by plants operating on RES (a compilation from various sources) ................................................................. 10

Table 6: Summery of USBR demonstration recommendations ................................... 10 Table 7: The cost of a wind-powered RO desalination (from Robinson et al, 1992).... 14 Table 8: Summery of potential CLW involvement in the development of

desalination programme in Western Australia ............................................... 17


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Introduction

Worldwide scarcity of fresh water resources and recent reduction in cost of the desalination technologies have enhanced the interest in fresh water production from saline or brackish waters. The worldwide capacity in desalination increased from 8000m3/day in the 1950s to 9,920,000m3/day in the 1980s (Tay, 1996) and was 130,000,000m3/day by 2000, majority of which was produced in the Middle East region: the Saudi Arabia share in the world capacity approached 25.9% in 1996 (2.3Mm3/d) (Al-Sahlawi, 1999), in Kuwait and Qatar water supply is 100% from desalination, while in Saudi Arabia and Bahrain is 50% and 40% respectively (Bremere, 2001).

Australia currently has only one percent of the total world desalination capacity (Gleick, 1998; Buros, 1999), and total fresh water production at plants greater than 100m3/day is 90,000m3/day. However the high water supply cost in remote areas and also deterioration of some natural water resources may force the adoption of desalination as the source of fresh water. A number of reviews on current state of desalination technologies progress and their potential application in Australia were undertaken (Water Corporation, 2000, Winter et al, 2001). Among them, the desalination technologies as a valuable tool in the natural water salinity management were also discussed.

CSIRO (CLW) capability in the area of water supply and water resources management in Australia may become an important basis for successful implementation of desalination technologies in the specific environmental and social-economic conditions in the country. This brief aims to review the current status of desalination technologies, identify trends in their development and indicate potential for CSIRO involvement in the development of desalination implementation in Australia.

The report was initially prepared in 2003 to support development of the CSIRO Water for a Healthy Country National Research Flagship project “Rural Towns Water Management”.


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1. Desalination processes and desalination cost

In general desalination technologies may be grouped into (i) thermal methods based on separation of fresh water from saline water during water phase changes (distillation, freezing distillation); (ii) membrane processes based on forced filtration though semi–permeable membranes (Reverse osmosis, Nanofiltration); (iii) Ions removal from saline feedwater under the influence of an electrical potential difference (electrodialysis), which also use a membrane technology for permeate and brine separation (Appendix 1). A combination of the technologies is also available (Figure 1). All costs presented herein are in US dollar amounts unless otherwise stated.

Figure 1: Categories of desalination processes (from MEDRC publications)

The installed world capacity consists mainly of multistage flash distillation and reverse osmosis processes with about an equal share of membrane and thermal processes. However older plants are distillation units, facing retirement. It is likely that in the future the total operating capacity of membrane units will increasingly exceed that of thermal units (Buros, 1999).

Desalination has limited application in many countries, including Australia, since the cost of the desalted water product generally exceeds development of natural water resources. With the upgraded designs and improved energy efficiencies, desalination units can currently deliver fresh water from the sea at costs that range from $0.46 to $0.80/m3, whilst freshwater from brackish water can now be produced at the rate of $0.10 to $0.20/m3, depending on the salt content (before water delivery to the consumers). The cost levels vary with respect to the local conditions, but nevertheless there has been a significant cost reduction from the costs of 10 years ago ($3.00 to $5.00/m3 for seawater desalination).


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By comparison, the costs to produce freshwater from ground and/or surface water in western countries range from $0.40 to $0.75 /m3 before distribution (Global Water Report, 2001). For instance water price in Europe is on average $0.70 with highest price in Germany ($1.41), France ($1.04) and UK ($0.93), and lower price in Italy is $0.35 (Barba et al, 1997). In WA the water cost (including distribution) varies from A$0.75-1.00/m3 ($0.45-0.61/m3) in the metropolitan area, A$4/m3 ($2.42/m3) along the main water scheme pipeline and to more than AU$10/m3 ($6.05) in remote areas (Gary Crisp, pers. comm.).

In general, the cost of desalination is determined by three factors1:

• energy requirements for a chosen desalination process and energy costs (Table 3)

• the feedwater salinity level and water quality (Figure2)

• production rate (economies of a size) (Figure 3)

Figure 2: Capital cost of reverse osmosis versus multistage flash (from Abou-Rayan and Khaled, 2002)

1 The desalination cost may also be reduced indirectly where there is a potential for an added benefit of desalination implementation (such as salt extraction or various chemical elements recovery from brine) (Turek, 2002)


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Figure 3: The relationship between the SWRO plant product cost (a) and capital unit cost (b) and the plant capacity (from Hafez and El-Manharawy, 2002)

Table 1: Energy use by various desalination processes (Water Corporation, 2000)

Process Gain Output Ratio (GOR)*

Electrical Energy Consumption

kWh/m3

Thermal Energy Consumption

kWh/m3

Total Energy Consumption

kWh/m3 MSF 8 – 12 3.25 – 3.75 9.75 – 6.75 13 – 10.5 MED 8 – 12 2.5 – 2.9 6.5 – 4.5 9 – 7.4 METC 8 – 14 2.0 – 2.5 12 – 6.5 14 – 9 MVC N/A 9.5 – 17 N/A 9.5 – 17 BWRO N/A 1.0 – 2.5 N/A 1.0 – 2.5 SWRO N/A 4.5 – 8.5 N/A 4.5 – 8.5

*GOR: Gain Output Ratio – the ratio of fresh water output (distillate) to steam.

(a)

(b)


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Table 2: The effect of advanced technology on the RO process by improving efficiency and lower costs, capacity of 5,000 m3/d (Glueckstern, 1999)

Current Advanced Brackish

water Seawater Brackish water Seawater

Recovery (%) 80-90 80-90 90-95 90-95 Energy Required (kWh/m3) 1.0-2.0 4.5-6.0 0.8-1.5 3.5-5.0 Operation materials (%) 2.0-2.5 2.0-2.5 1.0-1.5 1.0-1-5 Capital Cost ($/m3/d) 300-600 1,000-1,400 250-480 900-1,100 Labour 2-4 2-4 2-4 2-4 Chemicals ($/m3) 0.02-0.06 0.02-0.06 0.02-0.03 0.02-0.03 Membrane replacement ($/m3) 0.015-0.03 0.03-0.06 0.01-0.02 0.02-0.03 Total unit cost ($/m3) 0.26-0.58 0.73-1.19 0.19-0.41 0.60-0.85

Therefore the efforts toward reduction in the desalination cost are mainly related to energy recovery systems, higher process efficiencies, new or improved construction materials, decreases in membrane prices, high-tech ultra- or micro-filtration for pre-treatment, the use of waste energy from other processes, and the use of low-grade energy from electricity generating plants, all of which contribute to substantially decreasing external energy use and subsequently product water cost (Table 2) (Appendix 2).

2. Renewable energy sources (RES) and desalination

Since the cost of the fossil energy sources rises, the renewable energy resources become more attractive alternative as sources for desalination energy. It is particularly relevant to fresh water production in the remote areas, where fuel and water supply is often expensive, but where RES are in abundance.

Thermal energy, electricity or mechanical (shaft) power generated from solar energy (as photovoltaic - PV, or solar thermal energy), wind energy, geothermal energy, and to lesser extent tidal and wave (Appendix 3) have been harnessed for desalination. There are a number of possible combinations between desalination processes and different RES, shown in Figure 5, however many of these combinations may not be viable.


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Figure 4: Comparison of water quality and water price for operation mode

Figure 5: Potential use of various type of renewable energy in desalination process (from MEDRC)

Despite the considerable capacity of natural energy resources (Table 3), there are certain limitations to RES use in the desalination processes.

1. With the exception of geothermal energy, RES tend to have a variable rather than a constant power output. In order to provide constant power to the desalination plant, some form of energy storage is usually required.

2. RES and desalination plants are both relatively high cost technologies. It is therefore imperative that all system aspects must be optimised, e.g. the RES and the desalination system as well as the overall RES-desalination system integration.

3. For the selection of the desalination technology, the availability of feed water and its salinity/quality is an important parameter.

4. The amount of product water required per day is an important factor, which will influence the overall system design.


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Table 3: Capacity of natural energy resources in the World (from Belessiotis and Delyannis, 2001)

Classification Capacity Kind of Energy Solar Energy, kW 0.4 x 1014 Photon and heat Wind Power, kW 9.7 x 109 Kinetic Hydropower, kW 3.0 x 109 Kinetic Geothermal, kJ 4 x 1017 Thermal Tide Energy, kW 6.7 x 107 Kinetic OTEC, MW 30 x 109 Thermal

According to publications of the Middle East Desalination Research Centre (MEDRC) (Oldach, 2001), the choice for the combinations of RES/desalination technology is defined by feed water quality (salinity) and the requirements for product water (Table 4). Overall a wind-powered RO plant is considered to be the most cost-efficient (Table 5).

Table 4: Recommended renewable energy – desalination technologies combinations (Oldach, 2001)

System size Feed Water

available Product Water

RE Resource available

Small (1-50 m3d-1)

Medium (50-250 m3d-1)

Large (>250 m3d-1)

Suitable RE-Desalination Combination

Distillate Solar * Solar distillation

Potable Solar * PV – RO

Potable Solar * PV – ED

Potable Wind * * Wind - RO

Brackish Water

Potable Wind * * Wind – ED

Distillate Solar * Solar distillation

Distillate Solar * * Solar thermal - MED

Distillate Solar * Solar thermal - MSF

Potable Solar * PV – RO

Potable Solar * PV - ED

Potable Wind * * Wind – RO

Potable Wind * * Wind - ED

Potable Wind * * Wind - VC

Potable Geothermal * * Geothermal - MED

Sea Water

Potable Geothermal * Geothermal - MSF


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Table 5: Range of product water cost produced by plants operating on RES (a compilation from various sources)

Desalination method and energy source Cost of water product ($/m3) Solar thermal 0.87-5.48

PV-RO 0.56-3.14 W-VC 2.13-2.44 W-RO 1.5-1.77

3. Latest developments in the desalination technologies

A number of world research organizations have been continuously working on the improvement of the desalination process, aiming to reduce the cost of desalted water product. Most research involves engineering developments aimed at improvements in energy efficiency of desalination plants, use of waste energy or renewable energy sources, improvements of membranes for RO and other membrane based desalination processes and also search for new alternative desalination technologies. All of these tasks are within the field of engineering or chemical engineering research mainly conducted in GCC, USA, EU and also in Australia.

The US Bureau of Reclamation program “The Desalination and Water Purification Research and Developments”, started in 1997 and has funded 35 projects ($6.15million), conducted by various research organizations. Four projects were subsequently selected for demonstration scale development (Table 6).

Table 6: Summery of USBR demonstration recommendations

Project Description Benefits Estimated time and total cost in millions

Membrane bioreactors

Wastewater reclamation technology that may be combined with desalination technologies to purify wastewater to a level that meets or exceeds stringent drinking water standards.

Help allay fears about the purity of treated wastewater. Uses less space, equipment, chemicals and energy to be cost competitive with conventional methods and protect the environment.

3 years Government costs $4 million / Partner cost share $4 million

Innovative membrane test bed for seawater desalination

Combines three innovative research components (pre-treatment intake system, advanced membranes, and high pressure pumping system). Will allow continued research to develop environmentally acceptable concentrate disposal methods.

Will determine the combined cost reductions and efficiency improvements. Each component has proven to reduce costs and advance technologies.

3-4 years Government costs $2 million / Partner cost share $2 million

Dewvaporation Process humidifies / dehumidifies to evaporate water from saline solutions. Innovative technology uses inexpensive materials and recycled energy to evaporate water.

Provide a new, low cost, low maintenance treatment option for small communities. Unit is inexpensive to manufacture, energy efficient, and suitable for all water sources.

2.5 years. Government costs $500K / Partner cost share $500K.

Clathrate desalination

Improves freeze desalination techniques by using guest molecules to form ice-like structures at warmer temperatures.

Demonstrate effectiveness of freeze desalination compared to membrane processes. This process operates at low pressures and is relatively insensitive to source water quality.

2 years. Government costs $1.25 illion / Partner cost share $1.25 million.


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A brief description of other national and international research programs is given in Appendix 4.

Although commercial desalination capacity is dominated by membrane and thermal-based technologies, many alternative desalination and water purification methods are currently studied. It appears that conventional desalination methods are reaching technical maturity. Reduction in desalination cost will continue but in a slow (evolutionary) path. According to USBR significant drop in product water cost is likely to occur as a result of new technologies (Figure 6).

Figure 6: Effect of evolutionary and revolutionary technologies (USBR)

Some of most promising developments are listed below, and their implementation is expected to significantly reduce the cost of water desalination by 2010 (USBR Report, 2003).

• Ultrasonic (Supersonic);

• Membrane Combinations;

• Biomimetic (Active membranes; Biological sensors; Signaling capabilities);

• Ion Sorption (Zeolite crystallization);

• Sodium pump/biomimetic;

• Advanced membranes/separation (Porcelain; Thin-film; biologic; Bioreactors);

• Magnetics;


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• Nanotechnology (active/smart membranes),

• Capacitive desalination (Nanotubes or large surface areas; current swing sorption)

However information related to these technologies is not widely available.

One of the alternative desalination technologies, developed in USA, is linked to application of clathrate to sea water, which catalyses the formation of ice-like crystal at elevated temperature (about 12oC) and as a result reduces both the cost of ice formation from brine and the cost of melting the ice to form fresh water. An invention presented by the USBR allows formation of the clathrate ice crystals at an ocean depth of 610 m (McCormack and Andersen, 1995). A feasibility study of a new clathrate desalination process is presented that shows both the technical and economic feasibility of a publicly-financed desalination plant that would produce fresh water at a cost of approximately $0.45/m3 at a rate of 27300m3/day or 9.87 million m3/year. This plant design represents a major technical breakthrough by combining clathrate technology with ocean engineering technology. The process is relatively insensitive to water quality and may be used where RO application is limited.

Development of carbon-fibre technology (University of Illinois) aims to improve adsorption process with inexpensive glass fibres, which can be woven into wear-resistant fabrics. The glass fabrics are dipped in a phenolic resin and then "activated" through a chemical reaction that etches small pores into the carbon. The nature of the reaction determines both the pore structure and pore-surface chemistry, which control the adsorption properties of the coated assemblies. This allows highly selective systems for enhanced adsorption of specific contaminants, such as pesticides and chlorinated hydrocarbons. Another family of ion exchange fibres has been developed and are extremely effective at removing trace metallic contaminants, such as lead, arsenic and mercury.

Non-engineering developments are also under investigation, aiming to improve the desalination process and make it more cost efficient. The US Bureau of Reclamation defined the following actions as a part of successful and cost efficient desalination programme in USA.

• Characterize the raw water resource

• Find sustainable ways to use by-products and safely dispose brine

• Address implementation issues

• Commercialize and implement

• Collaborate at the global scale

Some of these actions fall within the scope of the geoenvironmental expertise.

4. Desalination in Australia

The largest desalination plant in Australia is an RO plant at Bayswater in New South Wales (Water Corporation), producing 35,000m3 of permeate per day (cf 100,000m3/day production at the Tampa Bay desalination plant, USA, and 120,000m3/day production at the Ashkelon desalination plant, Israel). Reverse osmosis for brackish water desalination is the most utilised method in Australia.


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At present water supply in WA is predominantly based on surface and groundwater resources. Sustainable water yield from surface water sources is 5207Mm3/Y, and currently only 13% of this amount is used in WA. The sustainable groundwater yield is 6304Mm3/Y and 18% of it is currently extracted. However the majority of the available groundwater is not suitable for potable use. Due to growing population it is predicted that water use will be doubled by 2020, which may increase local water resource demand to the sustainable limit (A State of Water Strategy for Western Australia, 2003).

The potential deficit in potable water supply prompted Water Corporation to undertake feasibility studies for a large-scale seawater desalination plant, which according to current estimation may produce water up to 80,000m3/day at price AU$1.2-1.3 /m3 ($0.74-0.80/m3) (cf. production cost at Tampa Bay of $0.46/m3, and $0.53/m3 at the Ashkelon plant). However the existing desalination plants in Western Australia produce potable water at much higher cost, which is partly due to their low production rate. The permeate cost at Ravensthorpe (capacity 180m3/day, BWRO) is about AU$6.5/m3 ($4.0), Denham (capacity 265m3/day BWRO) - AU$5.0/m3 ($3.08), Rottenest Island (capacity 200m3 /day SWRO) - AU$4.0/m3 ($2.46). The report of Water Corporation of WA also suggests that there is a potential for implementation of desalination techniques for water supply in Australia, which may become increasingly competitive with the natural water sources within next 20-30 years (Figure 7).

Planning Window

0.000.501.001.502.002.50

1990 2000 2010 2020 2030 2040Time Scale

Rel

ativ

e W

ater

Cos

t

Conventional Sources Brackish Water DesalinationSeawater Desalination Planning Window

Figure 7: Action and Planning Window for Water Resources Development (Water Corporation)

Specifics of water supply are defined by population density and also availability of fresh water sources. In WA, the majority of the population is concentrated in the Perth metropolitan area, while the population density in the rural areas is extremely low. Construction of a large-scale desalination plant is most feasible in the Perth region, however at present natural resources of fresh water are still cost efficient. Water supply to small settlements and farmland in the Wheat Belt area is expensive due to limited fresh water resources and distance from the main water supply arteries, which increases the price of water distribution. Opportunities for application of desalination to water supply needs appears to be mainly for small-scale systems in areas remote from the Metropolitan region and perhaps the GAWS.

The Murdoch University estimated the cost of a wind-powered RO desalination plant in Australian conditions in early 1990’s (Robinson et al, 1992) (Table 7). Considering the technology improvement during last 10 years, this cost may now be even lower, making it


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economically comparable with traditional water supply schemes in remote areas. However the challenge is to identify the most appropriate combination of RES and desalination technologies, which suit the environmental and social-economical conditions in WA (see Table 5).

Table 7: The cost of a wind-powered RO desalination (from Robinson et al, 1992)

Product cost Production rate m3/day AU$/m3 US$/m3

0.1 25.1 - 31.8 15.39-19.49 0.5 5.02 - 6.36 3.08-3.90 1.0 2.51 - 3.18 1.54-1.95

Potential application of water desalination technologies in the salinity management programmes (eg Salinity Action Plan) has recently been discussed. In many rural towns in WA the rising saline water table damages infrastructure and effects general land use. A desalination pilot plant was set up in Merredin as a part of a demonstration project. An intensive pumping programme was designed to control groundwater level and provide feed water for desalination plant. The recovery rate of the pilot plant is 80% (Cris Dedigama, pers. comm.). Using an evaporation pond construction cost of AU$50,000/ha and disposal capacity of approximately 2 metres per year, reduced water disposal costs would offset the cost of desalination product water by A$2.00/m3.

The Department of Agriculture has completed an extensive investigation on the salinity threat to rural towns. A Hydrogeological survey was conducted in 27 rural towns. Data on water table depths, groundwater salinity, and potential water yield are available, which may facilitate a desalination feasibility study as a part of the salinity management programme in these areas.

5. Conclusions: Potential CSIRO involvement in desalination programme development in WA

1. The desalination technologies remain an expensive option for potable water supply, however ongoing cost reductions are occurring

a. In Australia the cost of desalted water may become comparable with the current metropolitan water supply price by 2020 as a result of the mainstream technologies or by 2010 if alternative technologies, currently under investigation, become available at industrial scale

b. Current desalination technologies can produce potable water at cost as low as $0.46m3 in a very large scale RO desalination plant. The cost of water production by small-scale plants is higher, particularly when renewable energy sources (RES) are adapted to desalination process.

c. In general case the desalination methods become viable when water supply from the traditional sources is limited or expensive (such as a water export option, as in Israel) or when energy cost is low (as in the Middle East).


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2. Current water and energy costs and also local environmental and social-economic conditions in Western Australia favour implementation of small-scale desalination plants in the rural areas, possibly operating on the RES

a. The current cost of water supply in rural areas is in the range $2.4-6.0/m3

b. The cost of brackish water desalination may be as low as $0.46/m3 when traditional energy sources are used

c. The desalination technologies integrated with RES may produce permeate at the cost as low as $1.5/m3

d. The desalination methods may support the salinity management programmes in rural areas

e. The cost of reduced water disposal can offset the cost of desalination

3. The potential issues related to development of a desalination programme in rural areas are

a. The availability of potable water from existing distribution or natural sources

b. The availability of water resources for desalination and its quality, including groundwater hydrogeochemical composition and its fluctuation during water abstraction, which may affect the desalination process, particularly in a case of RO

c. The availability and cost of grid electricity

d. The potential for RES use for a water desalination plant

e. Optimisation of desalination plants in relation to the choice of the desalination methods, available materials, energy sources and water production rates

f. Brine disposal and/or utilisation

4. A convergence CLW research capability with opportunities for desalination arises from the following circumstances

a. The implementation of desalination technology is highly site specific, and a range of technologies may be favoured by local environmental and social-economic conditions, which requires their analysis

b. In a some range of remote water supply systems, direct application of conventional desalination technology may be immediately viable

c. Where saline water pumping is required to protect infrastructure or for any other purpose, reduced water disposal costs can strongly support the economics of desalination

5. The areas, where CSIRO may play a significant role in the development of the desalination implementation programme, may include the special analysis of natural resources, characterisation of water quality, proposed for desalination, and also the implementation of desalination technologies in the salinity management projects (Table 8).


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a. Spatial analysis of parameters controlling economics of water desalination (environmental and water/power supply).

i. An assessment of the water resources available for various desalination options, which may include mapping and characterisation of the saline aquifers, their resources and chemical composition of brackish/saline groundwater in order to facilitate the discission on desalination technology and pre-treatment options.

ii. Spatial analysis of the RES availability and capacity in various region of WA

iii. A combine spatial analysis of saline water resources and RES availability, which allows delineating potential areas where implementation of desalination techniques may become most cost efficient

b. Prediction of groundwater chemistry fluctuation during of water abstraction, which is particularly important when the membrane desalination is implemented

c. Characterisation of desalination brine for potential minerals recovery or salt extraction; and also choice of brine disposal option (evaporation basins / deep well injection / other)

d. Identification of the areas where desalination may contribute to the salinity management programme (the Rural Town Scheme or in the Wheat Belt farmland), which becomes particularly important and economically feasible as a part of salinity control measures

e. Environmental impact assessment of desalination plant development and operation

However it is unlikely that CLW may have a considerable contribution towards the Water Corporation programme focused on a large-scale desalination plant.


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Table 8: Summery of potential CLW involvement in the development of desalination programme in Western Australia

Potential role of CWL in desalination capability building in Western Australia Desalination requirement Objectives Possible Actions Suggested approaches

Assessment of the availability of potable water from existing distribution or natural sources

Review of the existing sources for potable water Cost-distance analysis

Mapping of saline aquifers Water resources Assessment of the availability of water resources for desalination and its quality Characterisation of saline aquifers (resources and chemical

composition)

Assessment of the availability and cost of grid electricity Review of the existing energy sources Cost-distance analysis

Energy resources Assessment of a potential for RES use for a water desalination plant

RES availability and capacity in WA (mainly wind/solar energy, wave energy)

Spatial analysis of available capacity of solar energy and wind energy in WA

Characterisation of water resources available for desalination (as above)

Characterisation of energy resources (as above)

Identification the areas where implementation of desalination techniques may become most cost efficient in relation to water and energy resources

A combine spatial analysis of saline water resources and RES availability

Optimisation of desalination plants in relation to the choice of the desalination methods, available materials, energy sources and water production rates

Assessment of natural water salinity and quality fluctuation during a long-term water abstraction, particularly in a case of RO implementation

Modelling, observation (?)

Identification of the brine disposal option

Desalination options

Brine disposal and/or utilisation Assessment of possible brine chemical composition as a source for mineral recovery and salt extraction

Assessment of requirements for water abstraction to control groundwater table and water yield available for desalination Environmental

considerations: land and water salinity

control

Utilisation of water resulted from groundwater table level control (pumped water or drain water) Assessment of natural water salinity and quality fluctuation

during a long-term water abstraction (as above)


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6. References

Abdul-Fattah, A. F. (1986). Supply of desalted water to remote arid zones. Desalination, 60, 161-189.

Abou-Rayan and Khaled (2002). Seawater desalination by reverse osmosis (case study). Desalination, 153, 245-251

Abulnor, A.M., Sorour, M.H., Hammauda, F.A. and A.M. Abdel Dayem, (1983). Squeezing desalted water costs by proper choice of the desalting technology and water management. Desalination, 44, 189-198

Andrianne, Jacques; Alardin, Félix (2002) Thermal and membrane processe economics: Optimized selection for seawater desalination. Desalination, 153, 305-311

Al-Sahlawi (1999) Seawater desalination in Saudi Arabia: economic review and demand projections. Desalination, 123, 143-147

Ammerlaan, A.C.F. (1982). Seawater desalting energy requirements as a function of various local conditions. Desalination, 40, 317-326

Avery W. H. and C. Wu (1994). Renewable Energy from the Ocean: A Guide to OTEC. Oxford University Press, New York.

Barba, D., Caputi P. and Cifoni D (1997). Drinking water in Italy. Desalination, 113, 111-117

Belessiotis V. and E Delyannis (1996). Solar energy: some proposals for future development and application of desalination. Desalination, 105, 151-158

Belessiotis V. and E Delyannis (2001). Water shortage and renewable energy (RE) desalination – possible technological application. Desalination, 139, 133-138

Bremere I., Kennedy M., Stikker A. and J. Schippers (2001). How water scarcity will affect the growth in the desalination market in the coming 25 years. Desalination, 138, 7-15

Birda, S. P. and W. Abosh (2001). Recent developments in water desalination. Desalination, 136, 49-56

Bolto B.A. (1984). The development of desalination in Australia. Desalination, 50, 103-114

Buros, O.K. (1999) The ABC’s of Desalting, International Desalination Association, Massachusetts, United States of America.

Cardona, E., Culotta, S. and A. Piacentino (2002). Energy saving with MSF-RO series desalination plants. Desalination, 153, 167-171

Chaiby M. T. An overview of solar desalination for domestic and agriculture water needs in remote arid areas. Desalination, 127, 119-133

Darton E. G. and E. Bruckley (2001) Thirteen years' experiences treating a seawater RO plant. Desalination, 134, 55-62

The Department of Agriculture of Western Australia (the publication site): www.agric.wa.gov.au/environment/publications


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Desalination and water purification research and development program (2001). Department of the Interior Bureau of Reclamation, Report to Congress (DWPR Report 67)

Dweiri S. F and M. I. Badranb (2002). Desalination: an imminent solution for the future water needs in the Aqaba Special Economic Zone (ASEZ). Desalination, 152, 27-39

El-Kady, M. and F. El-Shibini (2001). Desalination in Egypt and the future application in supplementary irrigation. Desalination, 136, 63-72

Gleick, P.H. (1998). The Worlds Water: the Biennial Report of Fresh water Resources 1998-1999, Island Press, USA.

Glueckstern P. (1999) Design and operation of medium- and small-size desalination plants in remote areas. New perspective for improved reliability, durability and lower costs. Desalination, 122, 123-140

Glueckstern, P. and Y. Kantor (1983). Seawater versus brackish water desalting technology, operating problems and overall economics. Desalination, 44, 51-60.

Glueckstern, P., Nadav, N. and M. Priel (2001). Desalination of marginal water: environmental and cost impact: Part 1: The effect on long-range regional development Part 2: Case studies of desalinated water vs. local desalination of marginal brackish water. Desalination, 138, 157-163

Glueckstern P., Thoma A. and M. Priel (2001). The impact of R&D on new technologies, novel design concepts and advanced operating procedures on the cost of water desalination Desalination, 139, 217-228

Guijt C.M., Meindersma G.W., Reith T. and A.B. de Haan (2002). Method for experimental determination of the gas transport properties of highly porous fibre membranes: a first step before predictive modelling of a membrane distillation process. Desalination, 147, 127-132.

Hafez and El-Manharawy (2002). Economics of seawater RO desalination in the Red Sea region, Egypt. Part 1. Case study. Desalination, 153, 335-347

Hammond, R.P. (1996). Modernizing the desalination industry. Desalination, 107, 101-109

Hamoda M. F. (2001) Desalination and water resource management in Kuwait. Desalination, 138 385-393

Harrison D.G., Ho G.E. and K. Mathew (1996a). Desalination using renewable energy in Australia. WREC, 509-513

Harrison D.G., Ho G.E. and K. Mathew (1996b). Renewable energy in the outback of Australia. WREC, 776-780

Hicks, D., Pleass, C., Mitcheson, G. R. and J. Salevan, (1989). Desalination, 73, 81-94.

Jurenka R. A. and M Chapman-Wilbert (1996). Maricopa ground water treatment study. Water Treatment Technology Program Report No. 15.

Kalogirou, S. (1997). Economical analysis of a solar assisted desalination system. Renewable Energy, 12, 351-367


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Kellogg, W. D., Nehrir M. H., Venkataramanan, G. and V. Greez (1998). IEEE Transaction on Energy Conversion. 13 (1), 70-75

Khan, A.H. (1986). Desalination Processes and Multistage Flash Distillation Practice, Elservier, Amsterdam.

Larson, T.J. and G. Leitner (1979). Desalting seawater and brackish water: a cost update. Desalination, 30, 525-539

Linstrum A., Crisp G. and G. Hughes (2000). Desalination in Western Australia. Hydro2000, 1, 357-362

Lokiec, F. and G. Kronenberg (2001). Emerging role of BOOT desalination projects. Desalination, 136, 109-114

McCormack R. A. and R.K. Andersen (1995). Clathrate desalination plant: Preliminary study. Water Technology Programme Report No.5

Malik, A., Hawlader, M.N.A. and J.C. Ho (1996). Design and economics of RO seawater desalination. Desalination, 105, 245-261.

Maratos, D. (2002) A new device to allow wave power to be used to reduce the energy consumption on existing desalination plants. EDS Newsletter, 8

Moatty, N (2001). Water management and desalination in Israel. Desalination, 136, 101-104

Mohsen M.S. and J. O. Jaber (2001). A photovoltaic-powered system for water desalination. Desalination, 138, 129-136

Mesa, A.A., Gomez, C.M. and R.U. Azpitarte (1996). Energy saving and desalination of water. Desalination, 108, 43-50

Morin, P.E. (1999). Desalting Plant Cost Update: 2000, International Desalination Association

Oldach R. (2001). Matching renewable energy with desalination plants. Middle East Desalination Research Centre, Report 97-AS-006a

Park M.H, Park N., Park H; Shin, H. S. and Kim B. D. (1997) An economic analysis of desalination for potential application in Korea, Desalination, 114, 209-221

Pique G.G. (2002). Breakthroughs allow seawater desalination for less than $0.50/m3. EDS Newsletter, 16, 9-11

Popkin, R. (1968) Desalination: Water for the Worlds Future, Frederick A Praeger Publishers, NY.

Rahim N.H.A. (2003) New method to store heat energy in horizontal solar desalination still. Renewable energy, 28, 419-433

Redondo J.A. (2001). Brackish-, sea- and wastewater desalination. Desalination, 138, 29-40

Rehman S., Halawani T.O. and M. Mohandes b (2003) Wind power cost assessment at twenty locations in the kingdom of Saudi Arabia. Renewable Energy, 28, 573–583


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Rheinlander J. and F. Grater (2001) Technologies for the desalination of typically 10m^3 of water per day: DESAL10 - a tool for the identification of appropriate de-central solutions. Desalination, 139, 393-397

Richards B.S. and A. Schafer (2002). Design consideration for a solar-powered desalination system for remote communities in Australia. Desalination, 144, 193-199

Robinson R., Ho G. and K. Mathew (1992). Development of a reliable low-cost reverse osmosis desalination unit for remote communities. Desalination, 86, 9-26

Sackinger, C.T. (1982). Energy advantages of reverse osmosis in seawater desalination. Desalination, 40, 271-281

Smith B.R. and E.A. Smith (1988). Desalination cost in Australia: a survey of operating cost. Desalination, 70, 3-15

Sommariva C., Hogg H. and K. Callister (2002) Maximum economic design life for desalination plant: the role of auxiliary equipment materials selection and specification in plant reliability. Desalination, 153, 199-205

A State of Water Strategy for Western Australia (2003). Government of Western Australia

Szacsvay T., Hofer-Noser P and M. Posnansky (1999) Technical and economical aspects of small-scale solar-pond-powered seawater desalination systems. Desalination, 122, 185-193

Tahri, K. (2001). Desalination experience in Morocco. Desalination, 136, 43-48

Talaat H.A., Sorour M.H., Abulnour A.G. and H.F. Shaalan (2002) The potential role of brackish water desalination within the Egyptian water supply matrix. Desalination, 152, 375-382

Tay J. H., Low, S.C. and S. Jeyaseelan S (1996). Vacuum desalination for water purification using waste heat. Desalination, 106, 131-135

Truby R. (2001). Desalination processes enhanced by multiple membrane systems. EDS Newsletter, 12, 2-4

Turek, Marian (2002) Seawater desalination and salt production in a hybrid membrane-thermal process. Desalination, 153, 173-177

Uche, J., Serra, L. and A. Valero (2001). Hybrid desalting systems for avoiding water shortage in Spain. Desalination, 138, 329-334

Van der Bruggen B. and C. Vandecasteele (2003). Removal of pollutants from surface water and groundwater by nanofiltration: overview of possible applications in the drinking water industry. Environmental Pollution, 122, 435–445

Visvanathafl C., Boonthanon N, Sathasivan A, and V. Jegatheesanb V. (2002) Pre-treatment of seawater for biodegradable organic content removal using membrane bioreactor. Desalination, 153, 133-140

Voivontas D., Misirlis K, Manoli E., Arampatzis G, Assimacopoulos D. and A. Zervos (2001) Desalination 133, 175-198


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Water Corporation (2000) Desalination-Creating New Water Sources, Water Corporation, Leederville, Australia.

Wilf M. and K. Klinko (2001). Optimisation of seawater RO system design. Desalination, 138, 299-306

Winter T., Pannell D.J. and L. McCann (2001). The Economics of Desalination and its Potential Application in Australia. Unpublished Report Department of Agriculture and Resource Economics, University of Western Australia

Wood, F.C. (1982) The changing face of desalination- a consulting engineers viewpoint. Desalination, 42, 17-25

Main Internet Sites on Desalination

European Desalination Society www.edsoc.com

Desalination research in US Universities: www.hawaii.edu/~nabil/drau.htm

Desalination programme by the US Bureau of Reclamation “The Desalination and Water Purification Research and Developments” www.usbr.gov/water/desal

Desalination technologies www.e-monitoring.com/bws/publications

Desalination Directory on-line www.desline.com

International desalination association www.ida.bm

Middle East Desalination Research Centre http://www.medrc.org

Roadmap report on desalination prospective in USA by EUSBR: www.usbr.gov/water/content/roadmapreport

World Wide Water www.desalination.com


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Appendix 1: Desalination Technologies

Distillation Processes

Based on water evaporation

Multistage Flash Distillation is the most widely-used desalination method worldwide. It involves heating saline water to high temperatures and passing it though vessels of decreasing pressures to produce the maximum amount of water vapour (fresh water).

Multi-Effect Distillation operates at lower temperatures but uses the same principles as multistage flash distillation.

Vapour Compression Distillation is generally used in combination with other processes, where the heat for evaporating water comes from the compression of vapour, rather than the direct exchange of heat.

Based on water crystallisation

Freezing processes are based on the natural phenomenon that ice crystals are constituted of pure water only, even when formed from a salt solution.

Hydrate processes exploit a bond between water molecules and certain chemical compounds such as CaSO4 or organic gasses (e.g. methane) to recover fresh water from saline solution.

Membrane Processes

Reverse Osmosis is a pressure driven process which forces saline water through a membrane, leaving salts behind.

IMS (integrated membrane systems): continuous microfiltration (CMF) or UF (ultrafiltration) in combination with RO and NF

Electrodialysis

Electrodialysis is a voltage driven process and uses an electric potential to move salts selectively through a membrane, leaving fresh water behind.


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Appendix 2: Factors influencing the desalination cost

Energy requirements and possible reduction in energy consumption

Theoretically, all desalination processes, have certain minimum requirements for energy. The theoretical energy needed to remove salt from a 4% salt solution is 3.6 MJ/m3 or the equivalent of 1 kWh/m3. The seawater contains between 3% and 4% salt. Brackish water contains between 0.5% and 1.5% salt, and therefore requires proportionately less theoretical energy.

However inefficiencies arise in all desalination processes due to the transport of energy in the process, or transport of matter at phase boundaries (Table 1) (Water Corporation, 2000). These inefficiencies increase the energy requirements of desalination methods, thus raising costs.

The major cost categories are capital costs, and operating and maintenance costs (O&M). The requirement for thermal or electric energy input can represent 50 to 75 percent of operating costs (Mesa et al., 1996). The form of energy available and environmental constraints related to the energy source contributes to the cost of energy for desalination (Ammerlaan, 1982; Abulnor et al., 1983; Water Corporation, 2000). Reverse osmosis has the lowest energy demand and this consequently makes it more attractive in many instances, compared to the well-tried multistage flash distillation (Sackinger, 1982; Glueckstern, 1999).

Rising world energy prices would alter the relative costs of different desalination methods, increasingly favouring reverse osmosis (Wood, 1982). As a result the current annual growth of 15–20% in SWRO plants announced or under construction will probably continue for a few years before it levels off.

There are number of methods adopted in the modern desalination plant to reduce energy consumption during the desalination processes. They may be grouped as follows

• Energy recover devices: application of energy recovery devices allowed reduction in the desalination power cost, e.g. from $0.73/m3 to $0.36m3 in the Vivendi BOOT plants in Caribbean’s, where power consumption reduced from 5.0 to 2.3 kWh/m3 (Pique, 2002).

• Combined desalination plant with power stations or use of waste heat: Tay et al (1996) demonstrate the application of vacuum desalination for the water purification using waste heat from a stream turbine.

• Development of hybrid plants (RO/Thermal or BWRO/SWRO) also allows reducing the energy consumption (Cardona at el, 2002).

Feed water salinity and quality

Two major factors influence the cost of desalination: general water salinity (as TDS) and water composition (chemical/biochemical quality).

The effect of water salinity on the desalination options

The higher salt content of the feedwater increases the operating costs because more sufficient technological options are required (e.g. the larger membrane area or the greater number of stages of distillation) (Popkin, 1968; Khan, 1986; Buros, 1999). Typically, the cost of desalting seawater is three to five times the cost of desalting brackish water from the same


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size plant for both membrane and thermal methods (Buros, 1999; Water Corporation, 2000). Membrane processes most economically achieve brackish water desalting, with reverse osmosis presently the cheapest process (Larson and Leitner, 1979; Glueckstern and Kantor, 1983), and may provide a recovery rate 25-45 % for seawater water and up to 90% brackish water (Wilf and Kilko, 2001).

The effect of water quality on the desalination options

The main concern regarding water quality in the plants using thermal desalination techniques is scaling: sulphate and bicarbonate ions in seawater can cause deposits of insoluble calcium and magnesium compounds at elevated temperatures. Within thermal desalination plants, adding suitable scale-control chemicals prevents the fouling of heat-transfer surfaces in the brine heater and heat-recovery stages. The seawater is also chlorinated to prevent marine growth in pipelines and heat exchangers. High-temperature polymer additives, derived from polymaleic acid, are mostly used in conjunction with on-load sponge-ball cleaning to remove soft-scale depositions.

RO is generally more sensitive to feed water quality, and become less productive at high water temperature (up to 40 degrees C), high salinity level, high salt density, high bacterial activity and high water pollution level (Birda and Abosh, 2001). For instance, an increase in feed water temperature results in an increased rate in salt and water diffusion across the membrane barrier at the rate of about 3-5% per degree Celsius (Wilf and Klinko, 2001). Fluctuation in feed water quality may be particularly damaging for the RO desalination units, which may cause unpredictable membrane fouling and also affect RO membrane flux (Glueckstern, 2001).

The feed water quality determines the membrane material (e.g. cellulose acetate or polyamide) and configuration (e.g. hollow fibre or spiral wound). Cellulose acetate membranes can be degraded by the formation of biological slimes on the membrane surface, while polyamide membranes cannot tolerate chlorine.

The cost of SWRO membranes contributed to the higher cost of water desalination, however the membrane cost has dropped up by over 65% from 1985 to 2002 in real terms (more if adjusted for infiltration), and membrane replacement now represents about 6% or less of the cost of produced desalinated water. The cost of chemicals for feed water pre-treatment and cartridge filter replacement has been reduced to 4% or less of total cost of produced desalinated water (Pique, 2002). Enhancement of membrane resistance to fouling, including biofouling, increase the membrane flux and their treatment and restoration and also resulted in reduction in energy requirement for desalination from a maximum of 25kWh/m3 to a level of 3 kWh/m3.

Raw water pre-treatment

Since desalination technologies, particularly RO, are sensitive to feed water quality, the implementation of an appropriate pre-treatment processes facilitates reduction in overall cost of permeates production. The latest water pre-treatment developments for RO desalination are based on IMS (integrated membrane systems), as continuous microfiltration (CMF) or UF (ultrafiltration) in combination with RO and NF. The IMS systems are still more expensive options for feed water treatment, but they allow producing better quality of feed water for RO. For instance, a proper pre-treatment system, such as membrane bioreactor – MBR, may be eliminated biofouling of membrane (Vasvanathan et al, 2002).

Use of nanofiltration (NF) as another water pre-treatment option allows water softening and also removal of natural organic matter (NOM) viruses, pesticides and other micro pollutants,


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heavy metal (arsenic) (Van der Bruggen and Vandecasteele, 2003). Among the new subjects that have been recently studied is the reduction of nitrate concentrations by NF.

Lately NF technologies are used in an integrated desalination system NF-SWRO (Sea Water Reverse Osmosis) and NF-MSF (Multi Stage Flash). The NF plant received non-coagulated filtered seawater and reduced turbidity and microorganisms and hardness. The concentration of monovalent salts was reduced by 40%, and the overall concentration of TDS (Total Dissolved Salts) was reduced by 57.7%, producing the permeate far superior to seawater as a feed to SWRO or MSF. This made it possible to operate a SWRO and MSF pilot plant at a high recovery (respectively 70% and 80%). The high water output in both integrated desalination systems, combined with a reduction of chemicals and energy (by about 25–30%) allows producing fresh water from seawater at a 30% lower cost compared to conventional SWRO (Al-So, 2001). Furthermore NF has become a sufficient option for brackish water desalination.

Economies of size

Economies of size arise when increases in the plant size (kilolitres of water produced per day) bring decreases in the unit fresh water cost (i.e. lower average total costs) (Figure3). Economies of size are evident in all desalination processes, but to different extents. Reverse osmosis exhibits little scope for economies of size, while distillation processes show the greatest economies of size. The operating and maintenance costs are not subject to economies of size, but are directly affected by the water quality to be treated (Morin, 1999). Exploiting economies of size for distillation methods has been proven an efficient means of reducing the cost of desalted water (Hammond, 1996). The cost of desalinated water may be an order greater, if produced by a desalination unit with capacity less than 1m3/day, in comparison with a large modern desalination plant (200,000m3/day). Two new SWRO plants (Tampa Bay, USA, and Ashkelon, Israel) currently produce water with the lowest cost of $0.46 and $0.53/m3 (respectively).


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Appendix 3: Renewable energy sources and desalination

Solar energy desalination

Solar energy desalination is generally the collecting of solar thermal energy that is used for desalination directly in solar still or that is converted to electricity first and then used in either thermal or membrane processes for desalination. First solar desalination device with capacity 23m3/day was designed in 1872 in Chile.

• Solar still (humidification) imitates a part of the natural hydraulic cycle. Solar still could provide the most economic supply of desalted seawater for a community in which there is abundant sunshine and a requirement for potable water in the range of 115 m3/day (Malik, et al, 1996). According to average estimates in Canada, about 1m2 of solar still is needed to produce 4.5L of water daily (El-Kady and El-Shibini, 2001). From the some sources an average daily solar radiation is equal to 5.5 kWh/m3.

• Distillation solar collector is used to concentrate solar energy so as to heat feedwater so that it can be used in the high temperature end of a standard thermal distillation process (Rer 14).

• Photovoltaics as a source of electrical energy used for operating RO or ED (El-Kady and El-Shibini, 2001; Mohsen and Jaber, 2001). Found to be most cost efficient in Saudi Arabia (Abdul-Fattah, 1986)

As in other methods the larger distillation units are more economical (Figure 4) (Kalogirou, 1997). The cost of water produced by a solar desalination in amount 20-400m3/day is $1.58/m3, while much smaller installations (0.25-10m3/day) generate twice more expensive permeate.

Wind

The maximum amount of wind power that can be withdrawn is 59.3% of the total wind energy. This theoretical maximum is not achieved by practical wind turbines, which typically are able to extract up to 50% of the wind’s energy.

Like PV, wind energy is best suited for desalination technologies, which require electrical power rather than thermal energy input. As a result wind turbines have been coupled with reverse osmosis desalination units. Wind power cost ranges $0.0234-0.1210/kWh between different locations and also the types of wind turbine (Rehman, 2003), which does not account for an energy storage.

As a stand-alone power system, wind was found to be more cost-effective than PV and hybrid wind/PV systems (Kellogg at el, 1998). Cost of desalinated water production is less for the wind powered RO and VC (1.68-1.87euro/m3 and 2.42-2.74euro/m3 respectively) than for PV-RO (3.78-3.76euro/m3) (Voivontas, 2001).

The wind duration analysis is important to be considered while selecting a site for development a wind power generation facility (Refman et al, 2003).

Geothermal energy

The amount of geothermal energy available on the Earth is about 8 × 1030 Joules, or 35 billion times the world’s present total annual energy consumption. However, only a tiny fraction of this enormous amount of heat can be extracted. For the purpose of water


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desalination, thermal fluid of sufficiently high temperature can provide heat for thermal desalination technologies or, in a case of high fluid temperature, electricity can be generated to power membrane desalination technologies or to supply the electrical power required for the pumps in a thermal desalination process.

Although not as common as PV, solar water heating or wind, geothermal energy has been used for many years and can be considered as a reasonably mature technology.

Ocean energy

Ocean thermal energy conversion (OTEC) uses natural thermal gradient between surface water and water at depth of 1000m or more to drive a power-producing cycle. In an open-cycle OTEC system, warm seawater is “flash”-evaporated in a vacuum chamber to produce steam. The steam expands through a turbine that is coupled to a generator to produce electricity. The steam exiting the turbine is condensed to freshwater by cold deep ocean water (Avery and Wu, 1994). However no commercial plant was built due to the high cost of construction and deployment.

There are two main methods of using the energy in the tides. Tidal turbines look similar to wind turbines, but are located beneath the surface of the sea. Currently, they are still at the prototype and demonstration stages and are not available commercially yet. Another method of utilising tidal power is by constructing tidal barrages, and using low-head hydropower turbines to generate electricity. Such schemes are very large-scale projects and therefore require a huge initial investment.

An ocean wave-powered RO desalination system consists of wave pump and RO module. There are small-scale systems in operation in Caribbean locations, which are feasible where ocean water is shallow and under constant wave action (Hicks at el, 1989). A simple device to connect the hydro-ram to an existing desalination plant has been designed and patented at Salford University, which is able to be incorporated into existing conventional desalination plants producing cost savings (Maratos, 2002).

The main research in the area of renewable energy use in for the purpose of water desalination is related to the following issues:

• Thermal insulation materials and geometry to avoid vapour leakage;

• Thermo-optical properties of surface structures and coatings especially for film and plastic sheet covering (glass cover - easy breakage, plastic – (a) ultra-violet resistance polyethylene, which may last 6-12 month; (b) ultra-violet resistance transparent polyvinyl chloride, which may last 2-4 years (El-Kady and El-Shibini, 2001)

• Sealing of the joints between the covering sheets and frames

• Storage of excess energy (solar or wind) during daytime for the continuation of the process at night (Rahim, 2003)

• Optimisation of a plant

Measures against salt and organism accumulation (enhance algae and micro-organism growth, which accumulate on the surface and reduce heat transfer to the brine).


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Appendix 4: Research activities in desalination

Mecorot Water Co (Israel) (Glueckstern, Nadav and Priel, 2001, Glueckstern, Thoma and Priel, 2001)

The Mecorot Water Corporation in Israel conduct intensive research programme, which mainly related to a various aspects of membrane technologies:

1. Raw water quality as a factor liable to affect an RO system.

a. The parameters related to membrane fouling are turbidity, Silt Density Index, particle size destitution, total and organic suspended matter, dissolved organic matter, biological load.

b. The parameters related to scaling are sparingly soluble salt, heavy metals, silica or in certain cases ionic composition itself (salinity, chlorides, nitrates)

2. While past research efforts were concentrated on evaluation and optimization of conventional techniques for pre-treatment, based on coagulation-flocculation and media filtration processes, all the RO pilot plants today evaluate both conventional and membrane pre-treatment systems - UF or UF and MF trains.

3. Hybrid BWRO/SWRO when rejected brine from BWRO is mixed with seawater, may have a major economical effect due to reduction in energy consumption and reduction in cost of supply of pre-treated feed water.

4. IMS: integrated membrane systems

5. Since there are limited sources of brackish water in Israel, major R & D efforts are focused on the increase product recovery.

Netherlands Applied Scientific Research (TNO)

Recent example of innovation is the combination of membrane technology with distillation technology through energy efficient and controlled transmembrane evaporation created by a temperature differential at a level below boiling point (Guijt et al, 2002). Although this technology, called membrane distillation, is not unknown, it has never before been developed into a technologically feasible, ecologically responsible and economically acceptable concept (Applied Scientific Research (TNO) in the Netherlands). The current plan is that around 2004 or 2005 one or two demonstration models will be operational on an industrial site of one of the participating industrial partners. Although the details are confidential, a recently approved patent application describes the general principles of the innovation, under the registered name Memstill.

The main features of the Memstill technology are:

• compact, easily operated modules, that require much less space than conventional units and can be designed and built to any specifications, from household applications to large-scale industrial use

• operational on renewable and/or conventional energy, especially waste energy, where it becomes very competitive with existing technologies;


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• an ingenious module design that reduces heat-transfer losses to an absolute minimum, resulting in an energy requirement for seawater desalination of 100–200 MJ/m3 of (waste) heat, or to the equivalent of 3–6kWh/m3 in energy;

• limited fouling and/or scaling, minimum pretreatment and maintenance, using synthetic components;

• targeted specific investment costs of $500/m3/day;

• targeted costs price of $0.50/m3.

Middle East Desalination Research Centre (MEDRC) (http://www.medrc.org)

For a systematic approach to research planning and management, the Center has defined ten Topic Areas into which projects are tendered. The Center's Research Advisory Council annually reviews the previous and recommends new projects for each of the following ten areas of research.

• Thermal Desalination (performance improvements in these process technologies and simplification of the design)

• Membrane Desalination (new membranes, membrane module & process design, energy recovery in RO processes, pretreatment methods, scaling and fouling fundamentals, and process and ancillary equipment design)

• Non-Traditional or Alternative Desalination (new concepts for non-traditional desalination processes and feasibility studies of desalination concepts that have not been fully explored)

• Operation and Maintenance

• Intakes & Outfalls (selecting appropriate intake and outfall systems based on the site conditions and development of new intake and out-fall systems)

• Energy Issues (reduction in energy consumption and the use of cheap alternative energy sources; application of renewable energy sources for desalination)

• Environment Issues (reducing and/or disposing of effluents including assessment of the composition of desalination plant effluents and develop procedures for assessment of environmental impact of desalination plant effluents)

• Hybridized systems (development of hybrid desalination processes for reduction in capital, operation and maintenance costs)

Desalination Research in Australia

A number of research organizations have a history of research in the area of water desalination.

Murdoch University, Environmental Science Division, conducted studies in renewable energy source and their applications for desalination plants, aiming for remote community use (mid 1990’s) (Robinson, Ho and Mathew, 1992; Harrison, Ho and Mathew, 1996a; 1996b)


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CSIRO, Division of Chemical and Wood Technology (Clayton) published a review on desalination technologies use in Australia and remote community water supply in 1980’. Division of Manufacturing Science & Technologies was involved in development new filtration media.

The University of New South Wales, Centre for Photovoltaic Engineering and Centre for Water and Waste Technology, Civil and Environmental Engineering studied the solar energy use for remote community water supply (Richards and Schafer, 2002). Also the Department of Chemical Engineering and Industrial Chemistry is a world know centre for advance membrane research

James Cook University, School of Engineering (Townsville) involved in advanced membrane studies (currently)

University of Western Australia, Agricultural and Resource Economics, prepared a review of the economics of different desalination technologies, the environmental impacts of desalination and its potential application in Australia (Winter, Pannell and McCann, 2001).

Water Corporation WA, published a review of modern desalination technologies and feasibility studies for large-scale desalination plants (2000).


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Appendix 5: Environmental impact assessment requirements for desalination plants in ASEZ (from Dweiri and Badran, 2002)

The first part is assessing and defining the pollution sources. The second is studying the receiving ecosystem and assessing the assimilative or carrying capacity of the system to abstain damage. The third step is designing and implementing mitigation and monitoring measures to alleviate damage to the environment. The following is a description of these steps.

Defining the pollution sources

Desalination plants whether located near the shore or inland have significant environmental issues that need mitigation unlike the common belief that the brine only is of primary concern. In addition to the proper disposal of the brine, ASEZA has the following significant issues to be considered in any EIA for the desalination plants operated in the zone.

1. Construction phase direct physical damage is to be avoided to the aquatic ecosystem, especially to the valuable coral reefs.

2. Operation phase

a. Site aesthetics, noise pollution, and land use.

b. Proper disposal of discharge. The concentrate and brine produced by thermal and RO membrane desalination plants are classified as industrial wastes. Since they do not contain Coliform bacteria, they are not technically considered municipal wastes. However, the concentrate and brine contain chemicals from the desalination and membrane cleaning processes. Two major types of disposal of concentrate and brine exist. The first is the disposal into sea, and the second is the disposal into land-based sites.

Disposal of brine and concentrate into sea

Several studies have identified the groups of components that are considered hazardous to the aquatic life and are discharged from either thermal or reverse osmosis desalination plants. The environmental effects are still not understood for some of these compounds. The following are the major types of additives that are discharged with the concentrate into the sea:

1. Corrosion metals. These metals get into the concentrate when the seawater corrodes the metal part of the plant. Thermal plant concentrate includes copper, nickel, iron, chromium, and zinc.These metals will accumulate in the sediment and affect the aquatic life.

2. Anti-scaling additives. Among the agents that were used to reduce and eliminate scaling is the polyphosphate, which hydrolyzes to orthophosphate at a temperature about 90°C. As a result, this will induce algal blooms in the area of concentrate discharge. The BELGARD EV2000, a polymer of maleic acid is used instead of the polyphosphate. It is not hazardous in drinking water and is widely approved. Its eco-toxicity is still not proven. Is does not accumulate in algae nor fish. Despite the conclusion that the BELGARD EV is safe, more studies are required to prove this theory in the Gulf of Aqaba.


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3. Antifouling additives and halogenated compounds. Chlorine and hypochlorite are commonly used as the main antifouling additive. Usually, they are used at a concentration of 2 mg/l. With good monitoring practices, the concentration of antifouling additives in the discharge is normally controlled at around zero or at a maximum of 0.2 mg/l. Chlorine coverts the naturally occurring bromides to bromine. Chlorine turns into chloride. As a result, the bromine, iodine, chloride, and halogenated compounds concentrations are increased. The risk is augmented when the discharge includes antifoaming additives or oil products. When oil compounds react with chlorine, the result is halogenated hydrocarbons, which are considered carcinogenic. Therefore, responsible monitoring and continuous sampling to control the process of dosing and discharge should be performed to contain the damage.

4. Antifoaming additives. The commonly used chemicals are fatty acids, fatty acid esters and acylated polyglycols. They are used to prevent foaming in thermal desalination plants at typical concentrations of 0.1 mg/l, but this depends on the algal and zooplankton content of the seawater. Overdoses have been detected in many plants. Antifoaming agents have adverse effects on the membrane of the cells. However, the detailed effects on the marine ecosystem in the Red Sea have not been scientifically established. Anti-foaming compounds react with halogens. More studies in this area are required.

5. Corrosion inhibitors additives. There are several products that are used for this purpose. No information on this was found in the available literature. However, the advantage of using these additives is the reduction of heavy metals that result from the corrosion of the metal parts of the plant.

6. Oxygen-removing additives. Sodium sulfite is added to remove traces of oxygen, which is a suspect agent in the corrosion process. The sodium sulfite is oxidized into sulfate. Sulfate is considered a normal constituent of seawater. However, the exact biological effects are still not determined.

7. Acid. Acid is added to desalination plants to reduce scaling. Sulfuric acid is commonly used for this purpose. Occasionally acid washes uses up to 7000 m of seawater and reduces its pH to 2. This acidic wash when returned to sea causes considerable damage to the marine life. A seawater volume of 25,000 m3 is required to neutralize the acid wash back into the natural seawater pH of around 8.

8. Brine and concentrate. The concentrates generated from thermal desalination plants are about lo-15% more saline that the original seawater salinity. The salinity of the brine is, however, much more for RO desalination plants& is 100-l 30% of the salinity of seawater. The marine life can tolerate a maximum increase in salinity of 1 practical salinity unit (psu). Recommended mitigation measures, taken before direct discharge into the sea, are by dilution with cooling seawater, and discharging the brine into deeper water where the salinity is naturally higher.

9. Heat. Thermal desalination plants normally discharge the concentrate with a temperature difference of 15-20°C greater than the natural ambient seawater. Also, dilution is required to reduce the temperature difference to less than 3°C to avoid the bleaching of the corals. However, if the concentrate is discharged into deeper sea, the effect on the marine life maybe less.


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Disposal of brine into land

Common disposal methods include the direct discharge into natural wadis, disposal to sewage treatment plants, deep-well injection disposal, land application as spray irrigation, and discharge into percolation ponds. Since land resources are limited in the ASEZ, and the susceptibility of the underlying groundwater aquifers is high, these methods are not encouraged and not preferable. For on-land brackish water RO desalination plants located near the sea, proper disposal of the brine into the sea is recommended.

Odour and air pollution

Gas emissions are released from desalination plants as a result of energy production necessary for seawater evaporation. Thermal desalination plants vary in the amount of emissions released depending on the energy source used. Energy sources include natural gas, crude oil and diesel oil. Since all types of oils generate sulphur dioxides, hydrocarbon, and non-hydrocarbons, natural gas is the choice for desalination energy in ASEZ.

Solid waste generation

It is required that plant operators estimate the volume of solid waste to be dealt with properly. RO plants produce much more solid waste than thermal plants since they dispose of old membranes. The reuse of these membranes has not proven successful yet and thus, the old membranes are considered as waste.

Assessment of the receiving body ecosystems

This requires the study of seawater properties and their interaction with the pollution sources.

Suitability of seawater for desalination

The question of suitability of seawater for desalination is two fold; the water as an input for the desalination plant and as recipient of the side product brine and the associated material.

Mitigation measures and monitoring plan

Post-audits and ecosystem pollution monitoring plans are necessary to be conducted both by staff and plant operators. Records of the monitoring are required to be provided in the EIA report. Moreover, emergency plans have to also be provided and coordinated with the civil dense and public security to ensure safety in and around the plants.

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