Reverse Osmosis & Thermal Desalination
for drinking water, industrial water & water recycling
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). Memmem-brane 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 segtreat-ments. 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
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 today’s 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.
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 Pumps
3 Energy Recovery system 4 RO Membrane Modules 5 Concentrate discharge
6 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
1 2
3 5
4 6
Raw water Product water
Nemmeli, India
Seawater RO, 100,000 m3/d 35 Al Wasia, Saudi Arabia
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 Arabia 50,000 m3/d, Pre-treatment
Combination of microfiltration and
reverse osmosis desalination.
An integrated solution.
Client: Majis Industrial Services SAOC Contract type: DBO - Design-Build-Operate Commissioning: 2013
Raw water: seawater
Product: potable water and process water Capacity: 20,000 m3/d
Process: 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 TDS Potable 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
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 SYSTEM
A 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-TREATMENT
Microfiltration 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 SYSTEM Pressure exchanger
POST-TREATMENT
1. 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 costs
In general terms, the employment of a modern process design and in particular the direct combination of microfiltration as a pre-treatment with reverse osmosis plant without additional cartridge filters and feeding pumps between MF and RO, has resulted in lower investment and operational costs. In addition, the plant foot-print is smaller than that of conventional RO desalination plants.
Further references
SEAWATER Muscat, Oman
OPWP Al-Ghubrah: 192,000 m3/d,
potable water, EPC, start-up: 2015 Ras Laffan, Qatar PUNJ-LLOYD, 12,000 m3/d,
Clean drinking water for one million
people in Chennai.
A complete solution.
Client: Chennai Metropolitan Water Supply and Sewerage Board (CMWSSB)
Contract type: DBO - Design-Build-Operate Start-up: 2013
O&M period: 2013-2020 Raw water: seawater Product: potable water Capacity: 100,000 m3/d
Main parameter: 43,000 ppm TDS Plant recovery: 40%
Process water quality: < 25 ppm TDS Potable water quality: 120-600 ppm TDS
From the sea to the tap. Using
technological competence and
professional management.
WABAG was awarded a contract for the design, construction and operational management of one of India‘s largest seawater RO desalination plants. The plant was built on a 16-hectare site 40 km south of Chennai and converts seawater into fresh potable water, which is supplied to one million people in the city’s southern suburbs.
SEAWATER INTAKE SYSTEM
Pipeline (1,600mm diameter, HDPE, length: 1,050m, sea-side depth: 14.1m)
Maritime intake filter
Intake chamber (upflow filter and sedimentation tank) PRE-TREATMENT
Disc filters, ultrafiltration ENERGY RECOVERY SYSTEM
Pressure exchanger DESALINATION
Reverse osmosis (spiral-wound polyamide) POST-TREATMENT
Remineralisation system: carbon dioxide absorber and lime-stone filter
Degasser tower
Nemmeli SWRO, Chennai, India
Reverse osmosis to boost drinking water supply volumes.
Further references
BRACKISH WATER
Al Wasia, Saudi Arabia: 200,000 m3/d,
potable water, start-up: 2010 Al Kharj Saudi Arabia: 50,000 m3/d, potable water,
start-up: 2009 SEAWATER Duqm, Oman: 6,000 m3/d,
potable and process water, DBO, start-up: 2010
Highly efficient water recycling plant
for a refinery expansion.
A sustainable solution.
Client: Indian Oil Corporation Ltd. (IOCL) Start-up: 2006
Raw water: secondary refinery effluent and various refinery/petrochemical process effluents
Product: boiler feed water and process water for PTA production Capacity: 21,600 m³/day
Technology: multi-stage treatment including ultrafiltration and reverse osmosis Plant: water recycling plant
Main parameter: TDS: 1,786 mg/l, silica: 98 mg/l, COD: 150 mg/l
Plant recovery: 90% WATER QUALITY
after RO: after demineralisation: TDS: 12 mg/l TDS: < 0.05 mg/l silica: 0.09 mg/l silica: 0.007 mg/l COD: 0
90% water recovery.
Completion of a tertiary treatment plant (TTP) for the refinery ef-fluent recycling for the Indian Oil Corporation Ltd., in Panipat, In-dia with the aim of achieving zero liquid discharge in combination with the recycling of wastewater for reuse as boiler feed make-up water. It is the first plant of its kind in India.
Sustained focus on zero liquid
discharge (ZLD).
High-rate clarification
Pressure sand filtration
Ultrafiltration (UF) – pressure-driven, hollow fibre system
Cartridge filter
Reverse osmosis (RO) – two-pass system in combination with a brine concentrator, 3 stages
Degasser tower
Demineralisation: RO permeate is polished by mixed bed, ion exchange filters
RO for water recycling at the Panipat Refinery, India
Closing the water cycle.
Further references
Paradip Refinery, Orissa, India: 54,000 m3/d, process water, start-up: 2015
Panipat Naphta Cracker Project, India: 20,900 m3/d,
boiler feed water, start-up: 2009 Essar Oil, India: 9,600 m3/d, cooling and
boiler feed water, start-up: 2011
Achieving synergy -
MED
The MED desalination process is normally used for medium-sized and large-scale thermal desalina-tion plants where thermal energy is available in the form of low-pressure steam (≥ 0.3 bar abs.) or waste heat, e.g. in combination with thermal power plants or industrial complexes. It therefore represents the most eco-nomic distillation process from an en-ergy efficiency perspective.
Main advantages
The MED process operates at low temperatures with high thermal effi-ciency, providing:
Low thermal energy consumption
Low operating costs
MED-TVC - enhanced
efficiency
Standard MED plants are equipped with thermal vapour compressors for enhanced efficiency.
As a rule, the TVC desalination process is employed for small to large-scale thermal desalination plants where thermal energy in the form of medium pressure steam (>3 bar) is available, e.g. in combination with thermal power plants or industrial complexes and this results in low opera-tional and investment costs.
Therefore, from cost-efficiency standpoint, TVC distillation is the most advantageous, steam-heated process for medium-sized plants.
Main advantages
The TVC process operates at low tempera-tures with high thermal efficiency, providing:
Small to large train sizes
Low investment costs
Thermal Desalination technologies
Multi-effect distillation
Selected references
AVR, Rotterdam, The Netherlands: 24,000 m3/d,
process water CMI, Marmara, Turkey: 3,360 m3/d, process water
Selected references
Tobruk, Libya: 13,333 m3/d, potable water,
start-up. 2016
Suralaya, Indonesia: 6,000 m3/d, process &
potable water, start-up: 2010
Rembang, Indonesia: 6,000 m3/d, process &
potable water, start-up: 2010 GMDC, Kutch, Gujarat, India: 2,400 m3/d,
process water, start-up: 2006 Benghazi North, Libya: 4,800 m3/d, process
water, start-up: 2005 Thermal desalination (multi-effect
distil-lation) takes place in a series of vessels (effects) in which the principle of con-densation and evaporation at reduced ambient pressure is applied. This per-mits the saline water to undergo boiling without the need to supply additional heat after the first effect.
Thermal desalination
– the advantages
Stable and proven process
Minimal or no need for pre-treatment
High output water purity level (≤ 10 ppm TDS)
Ideal in combination with power
plants
Simple operation with low mainte-nance costs
MED-MVC - the
stand-alone solution
Where an external steam source is unavailable for heating, standard MED plants are equipped with mechanical vapour compressors (MVC). These pro-vide heat for water evaporation through mechanical steam compression. The MED-MVC desalination process is normally used for small to medium scale thermal desalination plants where thermal energy is unobtainable. The mechanical compressor is electrically or diesel driven.
Main advantages
No need for external thermal energy
A robust process
Multi-stage flash
(MSF) - large-scale
thermal desalination
technology
MSF - the big solution. The MSF de-salination process is utilised mainly for large-scale, thermal desalination plants where thermal energy in the form of low-pressure steam (>2 bar) is avail-able, e.g. in combination with thermal power plants or industrial complexes. Saline water is heated by steam and then fed into a series of vessels (effects) where reduced pressure leads to imme-diate boiling (flash) without the need for additional heat.
Main advantages
Large train sizes
Low energy consumption
MED – XL™ and
XXL™
Recently, the capacity of thermal sea-water desalination units has begun to increase considerably. In response to this trend, WABAG has designed and optimised its XL (in the range of 13,500 - 25,000 m3/d) and XXL units
(from 25,000 up to 45,000 m3/d).
In these newly developed systems, all the preheaters are enclosed in an extremely compact manner, which not only prevents heat losses, but also guarantees highly efficient operations. These large units can be built as MEDs or MEDs with thermal vapour compressors (MED-TVC).
Selected references
Burrup Penninsula, Australia: 3,600 m3/d, process & potable
water CHP, Taba, Egypt: 2,000 m3/d, potable water
Selected references
REFURBISHMENTS Khoms, Libya: 30,000 3/d,process water, start-up: 2008 Zliten, Libya: 30,000 m3/d,
potable and process water, start-up: 2008
VA TECH WABAG GmbH Dresdner Straße 87-91 1200 Vienna, Austria Tel.: +43 1 251 05 0 [email protected]
VA TECH WABAG LIMITED
“WABAG House“
No.17, 200 Feet Thoraipakkam – Pallavaram Main Road
Sunnambu Kolathur Chennai 600 117, India Tel.: +91-44-3923 2323 [email protected]
WABAG offers sustainable solutions for:
n Drinking water treatment
n Industrial and process water treatment
n Water reclamation
n Sea and brackish water desalination
n Municipal wastewater treatment
n Industrial wastewater treatment n Sludge treatment
WABAG is one of the world’s most innovative water treatment companies with know-how in specific techno-logies and in-house developed processes such as: n Biofiltration BIOPUR®
n Moving bed biology FLUOPUR®
n Activated sludge Hybrid™, SBR, processes MICROPUR-CAS®
n Membrane bioreactor MARAPUR®,
MICROPUR-MBR®
n Membrane filtration RO, MF, UF, NF
CERAMOPUR®,
CERAMOZONE®
n Denitrification BIODEN®, ENR®
n Oxidation processes ADOX®, BIOZONE®
n Adsorption processes CARBOPUR®, PACOPUR®
n Thermal desalination MED, TVC, MVC, MSF
MED XXL™
n Fine sieving MICROPUR®
n Deep bed filtration in various designs n Anaerobic sludge digestion
including advanced energy recovery
The WABAG Group represents a leading multinational player with companies and offices in 20 countries and a focus on emerging markets in Eastern Europe, Africa, LATAM, Middle East, South East Asia, China and India.
www.wabag.com
sustainable solutions. for a better life.
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