Reverse Osmosis & Thermal Desalinationfor drinking water, industrial water & water recycling

Desalination technologies

Finding new approaches through R&D On the strength of our extensive experience, our current focus is on the development of mem-brane distillation (MD). Membrane distillation is a thermally powered separation technology based on hydrophobic membranes, which allows higher concentration efficiency at lower cost.

Pilot tests are currently under way with the aim of studying concentration performance in the case of various effluents (such as produced water) and brines (such as concentrates from rec-lamation plant ROs). In this context, the development and design of an ideal pre-treatment for MD is extremely important.

Moreover, progress has been made in the area of minimising brine return volumes and this constitutes a step towards zero liquid discharge (ZLD).

WABAG - for over 90 years a synonym for innovative and successful water engineering solutions.

WABAG is an international supplier of water and wastewater treat-ment systems for both municipal and industrial segments. It is one of the innovative leaders in this field and in particular, is one of the few companies in the world to offer a comprehensive spectrum of technologies for the desalination of sea and brackish water:

Reverse osmosis Thermal desalination (MED, TVC, MED-XL and XXL, MVC, MSF) Electrodialysis (ED) Ion exchange (IX)

With more than 30 years of desalination experience, WABAG has designed and built over 100 plants worldwide.

At present, the widely preferred technologies for the desalination of sea and brackish water are: Membrane technology: reverse osmosis (RO) Thermal methods: multi-effect distillation (MED)

These technologies can be utilised for both the production of po-table water and industrial process water, and form the basis for optimum and customised solutions. Desalination technologies are also of increasing importance in the field of water recycling sys-tems and demineralisation, while the employment of membrane technologies such as reverse osmosis allows the reuse of indus-trial effluents as highly-purified process water, e.g. as boiler feed water.

What makes WABAG a preferred partner? A comprehensive desalination technology portfolio

Proven process know-how and expertise as well as an under-standing of entire systems

The provision of complete solutions: EP, EPC, DBO, BOOT

In-house R&D centres in India, Austria and Switzerland, which guarantee the optimisation and further development of desali-nation technologies

Experience as a desalination plant operator

A multinational presence and long-term experience

The integration of desalination plants with water reclamation systems

Freedom of choice on the most suitable membrane systems

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Reverse Osmosis or Thermal Desalination

The larger the salt content of the untreated water and the greater the required degree of purity at the desalination output, the higher the energy costs.

In the past, reverse osmosis installations required sizeable amounts of electrical power. However, owing to increased energy optimisation, these processes have now become far more cost-efficient. In todays world, RO is indispensable for the supply of potable water in countries lacking adequate ground or surface water resources. It has emerged as the most economic solution where residual steam is unavailable as an energy source.

By contrast, thermal seawater desalination using residual steam as an energy source is the most appropriate solution in power plants and offers major O&M savings. Thermal MED in-stallations, for example, are operated with low pressure exhaust steam or with output steam from steam turbines. For steam pres-sures above 2 bar, thermal MSF would then be appropiate. When such energy is available this process is most suitable.

REVERSE OSMOSIS

THERMAL DESALINA-

TION

WABAG is one among the very few companies in the world to offer both technologies on standalone or hybrid basis.

Al Ghubrah, Seawater Intake sinking

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RO the advantages:

Proven and time-tested technology Relatively low investment costs as compared to thermal methods Application flexibility - from very small (< 100 m3/d) to large installations (> 100,000 m3/d) No cooling water requirement Less energy consumption than with an MED system

RO is a pressure-driven process. Saline water is forced through semi-permeable membranes under pressure, thereby separating the saltwater into a freshwater stream (known as permeate) and a brine stream (concentrate).

Typical process steps in an RO system:

1 Pre-treatment (protecting the RO membranes)2 High Pressure Pumps3 Energy Recovery system4 RO Membrane Modules5 Concentrate discharge6 Post-treatment (remineralisation, disinfection)

The recovery percentage of purified water de-pends upon various factors that include mem-brane size and internal structure, temperature, operating pressure and membrane surface area.

Due consideration given to the economic factors such as: Energy recovery Membrane durability Chemical consumption Process automation

Reverse Osmosis Desalination

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4 6Raw water Product water

Nemmeli, IndiaSeawater RO, 100,000 m3/d

35Al Wasia, Saudi Arabia Brackish water RO, 200,000 m3/d

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Saving energy & costs

Employing pressure exchanger systems.

The RO process does not require thermal energy, but needs elec-trical power mainly due to the high pressure pumping required to obtain flow through the RO membranes. Brine energy recovery systems have also been optimised in order to reduce energy con-sumption and have proved to be highly successful.

Complete and Exclusive

Customized solutions

WABAG supplies RO plants for various types of raw water such as seawater, brackish water and industrial effluents. As a provider of end to end solutions, WABAG delivers the entire process from the raw water onwards, including deep seawater intake and outflow structures to the post-treatment of product water and product water pumping stations.

On the strength of its experience in design, construction and op-eration of plants of varying sizes, WABAG offers economically ad-vantageous and technically proven solutions for every application.

Highly effective pre-treatment systems are extremely important

From filtration to micro- and ultrafiltration

WABAG lays a special emphasis on efficient pre-treatment. In that, apart from conventional filtration technologies, highly effec-tive micro- and ultrafiltration systems are employed.

For example, WABAG designed and built the first plant in Oman (Duqm, Al Wusta region) to use microfiltration units for pre-treat-ment and subsequently this successful combination was also used in the desalination plant for the new Sohar International Port (start-up 2013), where an in-line RO system was successfully ex-ecuted.

The Nemmeli RO-drinking water plant in Chennai, which is one of the largest plants of its kind in India, employs ultrafiltration mem-branes for highly effective pre-treatment upstream of the RO sys-tem.

WABAG is an established name in various pre-treatment tech-nologies. 5 Duqm SWRO, Oman

6,000 m3/d, Pre-treatment (microfiltration)

Al Kharj BWRO, Saudi Arabia50,000 m3/d, Pre-treatment

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Combination of microfiltration and reverse osmosis desalination.

An integrated solution.

Client: Majis Industrial Services SAOCContract type: DBO - Design-Build-OperateCommissioning: 2013

Raw water: seawaterProduct: potable water and process waterCapacity: 20,000 m3/dProcess: reverse osmosis with self-cleaning filters and membrane pre-treatment

Microfiltration-based Inline RO system - reduced CAPEX, OPEX and footprint.

Main parameter: 44,000 ppm TDS Plant recovery: 40% Process water quality: < 25 ppm TDSPotable water quality: 120-600 ppm TDS

Completion of a reverse osmosis (RO) based seawater desalina-tion plant producing 8,000 m3/day of industrial process water and 12,000 m3/day of potable water, thus contributing substantially to a continuous water supply at Sohar Industrial Port Area, Sultanate of Oman.

Sohar International Port SWRO, Muscat, Oman Most modern desalination plant for drinking and industrial water production.

Best practice references

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Objectives Ensuring reliable operation even during difficult raw water intake conditions such as red seawater tides Continuous RO water production Low life cycle costs

SEAWATER INTAKE SYSTEMA 2.6 km, 800 mm diameter pipeline feeds the plant through a tap off from an existing cooling water pump manifold. Two 300 micron automatic self-cleaning filters are installed midway through the pipeline.

PRE-TREATMENTMicrofiltration to handle inlet TSS up to 80 ppm obtaining at the output SDI of less than 1 (input SDI 35+). Configuration: 7 Skids, each with 80 modules and 420 m3/h capacity.

DESALINATION Sea- and brackish water RO 3 units: 12,000 m3/d, double-stage Seawater RO 2 units: 8,000 m3/d, single-stage

ENERGY RECOVERY SYSTEMPressure exchanger

POST-TREATMENT1. Post-treatment for pH adjustment and disinfection of potable water.2. Neutralization system for brine.

Reduced energy consumption With its hybrid membrane system (high- and low-rejection) WABAG has met the stringent quality of product water with op-timized energy consumption. Energy recovery devices are de-ployed to extract power from the SWRO reject stream.

Modern design reduces costsIn general terms, the employment of a modern process des