Reverse Osmosis for Production of Drinking Water

Description of technology:

The treatment of brackish or seawater using reverse osmosis is the most commonly used technology for the removal of solutes and the reduction of conductivity.

Desalination systems usually have a pretreatment unit (prefiltration) for the protection of the membranes. This unit includes a pressure sand filter and then cartridge filter, as well as pH adjustment and the use of antiscalant to protect membranes.

After prefiltration, the water to be treated, is transferred by pressure in reverse osmosis membranes. This is accomplished by high pressure pumps operating in 70-80 bar. Depending on the characteristics of the “dirty” water (surface water, well, seawater etc.) a two or three step RO system can be used in order to achieve the desired product quality. So finally is achieved pollutants removal even at a rate of up to 99.5% -99.8%.


  • Compact, flexible system
  • Prefabricated, fast installation with minimal civil works
  • Efficient process with a high quality product
  • Small footprint
  • Independent – automatic operation

Case Study:


This contract icludes the financing, design, construction, maintenance and operation for three years of a seawater desalination plant with the method of reverse osmosis.

In summary, the unit of Paphos desalination consists of the following:

  • Underwater pipeline 600m length, Φ800, from HDPE, for the collection of seawater.
  • Johnson Filter at the end of the underwater pipeline at a depth of about -10 meters for the removal of larger particles. The filter is self-cleaned by blowing air and has chlorine disinfection system.
  • Pumping station for the seawater, founded by intersecting piles, with 7 pumps with a total capacity 4.200m3 per hour.
  • Refining system consisting of 12 sand filters that remove particles with diameter up to 20 microns
  • Second refining system with 10 cartridge filter that remove particles with diameter up to 5 microns with the possible addition of flocculant and disinfectant if required.
  • Pumping station for the feeding of reverse osmosis units.
  • 7 arrays of reverse osmosis membranes with a capacity of 5,000 m3 / day each.
  • 7 high pressure pumps (> 62 atmospheres), one for each array.
  • 7 ERI type energy saving systems. (One for each array membrane).
  • 3 arrays of reverse osmosis membranes in second pass for further removal of boron.
  • addition systems for gas CO2, lime and caustic soda to correct the acidity and increase the hardness of the product.
  • sodium hypochlorite solution addition system.
  • clean water pumping station with 7 pumps with a capacity of 250 m3 per hour each.
  • pressure pipeline with 5,000 meters length made of ductile cast iron (ductile iron), Φ600, for the transportation of produced water.
  • submarine pipeline for the disposal of brine with 1000m length, Φ600 with a diffusers system suitable for the disposal of brine.
  • Pressure stainless steel pipes transferring water in various parts of the installation.
  • Quality and quantity control systems – on line pH meters, conductivity and residual chlorine. Also, every four hours chemical analysis is performed in the laboratory of the plant for the following parameters parameters of turbidity, color, conductivity, pH and daily water is analyzed for boron, total hardness, alkalinity, calcium, odor, taste and total dissolved solids.

Project Data:


36.039.735 €

Type of water



35.000 m3/day potable water


20.000 m2