Desalination Solutions | Water Desalination Systems

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As water quality, security and reliability becomes increasingly important in supporting our thriving communities, achieving high levels of water treatment is critical to delivering these outcomes. Water utilities are having to meet community expectations for safe and reliable water supplies amid climate change, water scarcity and environmental requirements, and tightening operating budgets. As a climate-resilient source of water, desalination plants are becoming increasingly important for future communities to supply drinking water.

Our Water Treatment team takes a holistic and client-centric approach, offering engineering and advisory services for the full spectrum of water issues including water treatment, water security of supply, drainage and flood control, hydraulic structures, hydroelectric facilities, irrigation systems, sedimentation and erosion control, hydrogeology, potable water supply, reclaimed water planning and design, and management of biosolids. We are highly attuned to the technical, ecological, and regulatory issues that face the water industry.

Our Environment and Stakeholder Engagement group provides technical input into the design of water infrastructure, and advises on avoidance, licensing and environmental approval in accordance with current legislative and regulation requirements.

Desalination engineering benefits

Consideration of construction risks, water quality, security durability and reliability in design.
Reduced operational costs through process optimization and unmanned operations.
Reliability of equipment and provision of flexibility to avoid operational problems. Building for demand and allowing expandability, enabling our clients to optimize operations and to defer capital expenditure.
Smart and effective asset lifecycle management.
Efficient planning and environmental approval pathways through concise reporting.
Holistic approach to design by considering environment, community and sustainability.

In inland and coastal areas where conventional freshwater resources are unavailable, or in areas where water is in short supply, desalination of brackish water and seawater, grey water recycling and reclaimed wastewater are alternative or “new” water supply sources for clean, safe water.

Desalination converts brackish or saline water to fresh water that is suitable for potable, agricultural and industrial uses.

Overview of water desalination systems components

Water desalination systems have four main components: the intake system, pre-treatment steps, the actual desalination system and the concentrate disposal systems.

Reverse-osmosis (RO) is now the most commonly used desalination process for new systems due to its typically lower energy use and operational costs. However, multistage flash distillation (MSF), multiple-effect distillation (MED), electrodialysis reversal (EDR), evaporators and other processes are preferred in some circumstances.

It is important to use a raw water source containing as low amounts of organic materials as possible. The choice of equipment for water pre-treatment is an important part in designing a new desalination plant.

A good pre-treatment with high quality feed water provides the required conditions for high recovery and a high-flux operation which will results in significant reduction of the investment cost. Therefore, raw water supply quality and concentrate disposal requirements correspond to critical feasibility, technology selection, and regulatory and economic issues.

In the example of RO, the membrane often gets fouled by colloidal particles, dissolved organics in feed water which results in biological growth on the RO membrane. If cleaning must be done too often, it will result in a larger capital investment for improved RO pre-treatment. The objective of the pre-treatment is to reduce the concentration of fouling impurities in the feed water so that that we have a stable long-term performance of the RO membrane.

Studies are performed covering location investigation, environmental impact assessment, water balance, water cost calculations, thermodynamic considerations and material properties to ensure minimum cost and optimum process. Efficiency, reliability and maintenance costs are forecasted—with reservoir capacity, blending plant, intake and brine effluent systems—and are then considered to meet water consumption and site requirements.

WSP’s desalination areas of expertise

Design of open and subsurface seawater intake systems
Brine discharge and related hydrodynamic modelling
Brackish water wellfields
Concentrate disposal injection well systems (disposal of substances not suitable to return to the sea, i.e dewatered sludge from pre-treatment containing chemicals, CIP fluids etc.)
Pre-treatment and membrane technologies
Seawater Reverse Osmosis (SWRO) systems
Multistage flash, multiple effect distillation systems
Enabling infrastructure (high voltage power and transfer pipelines) systems
Experienced with small- and large-scale floating installations for marine/offshore desalination projects
Energy recovery – kinetic and thermal recovery or reuse in the desalination process
Compliance with rules, regulation, regulatory issues, and classification societies within the environmental area

Mitigating environmental impacts of water desalination projects

WSP’s experts have a clear understanding of the environmental issues involved in water desalination projects. We have provided design, peer reviews and construction management of multistage flash, multiple effect distillation and reverse osmosis systems.

We have also designed, permitted and provided construction management for brackish water wellfields, subsurface seawater intakes and concentrate disposal injection well systems. Our engineers have hands-on experience with all types of pre-treatment and membrane technologies, gained through involvement in desalination projects of all sizes.

Water quality

Contamination, related to failing infrastructure and extreme weather events, is becoming more frequent, which affects the ability of treatment systems to effectively meet the most elementary requirements. In some instances, finding alternative water resources to maintain clean drinking water is the only way forward. This can be achieved through desalination, or by treating a contaminated or wastewater source for industrial use, thereby reducing the demand on drinking water supply.

To combat some contamination issues, more stringent environmental regulations have been imposed, either to maintain receiving water quality or to restore the receiving water to a previous cleaner condition. In either case, there is always a residual waste stream to be considered.

The scope of our work includes the water desalination process and pre- and post-treatment. Within post treatment, we address potabilization (i.e. remineralization, pH adjustment, corrosion control etc.). Our work also encompasses seawater intake and brine disposal, bulk water infrastructure, including high-lift pumps, pipelines and storage facility, as well as managing all civil, marine, electric and instrumentation.

We ensure our clients’ projects are implemented to specification and comply with local and international standards. We have a track record of delivering projects that meet the client performance requirements and are delivered on time and at budget.

Beyond just desalination plants, WSP is recognized as a leading technical and project management consultant on integrated power generation and sea desalination projects. Our track record includes delivering over 180,000 MW of power generation projects and over 2,600 MIGD (12,000 ML/d) of water generation capacity at over 600 sites worldwide.

Marine intake and outfall

WSP has extensive experience in the marine modelling, design and implementation of marine pipelines (intakes and outfalls) for desalination. Our typical involvement and experience in marine pipelines and other marine conduits are as the marine consultant.

For desalination, raw water is normally delivered to the pre-treatment works at the plant and brine accepted at the reject (waste) tank. As our expertise is specifically coastal engineering, we understand the marine environment and how to work and design within it. This expertise enables us to assess hydrodynamic and water quality around intakes and outfalls using oceanographic study and modelling.

Based on characteristics of the receiving water body and outfall effluent, we use state-of-the-art tools to model effluent dilution and plume propagation.

Seawater abstraction and discharge

Water abstraction from or discharge to the marine environment remains an important engineering requirement. Both abstraction and discharge are subject to strict environmental legislation to ensure the impact on oceans and inland water bodies is minimized.

Traditionally, seawater abstraction has been primarily used as cooling water for power generation plants, especially in the nuclear sector.

The cooling of buildings in hot and dry climates has also gained popularity in recent years, especially where cold water is available. In addition, the scarcity of drinking water in many arid regions has given rise to desalination and a new use for abstracted seawater.

Modelling and optimization

WSP’s work also extends to environmental disciplines that entail financial viability modelling, plant operation optimization and numerical hydrodynamic and dilution modelling, among other services.

Project investigations

WSP also works with clients to explore public and private markets to determine the best available funding source for desalination projects. We have undertaken a wide range of project investigations covering the environmental, technical and economic aspects of various types and capacities of water desalination schemes.