R.T.S. ROCHEM® Reverse Osmosis Freshwater

Seawater Desalination on ships and offshore platform

We produce the potable water from the sea, without chemicals during operation. Standard Rochem freshwater generators from 2.000 ltr/day up to 100.000 ltr/day. On Customer’s request, special design up to 800.000 ltr/day potable water.

  • RO plants are automatically flow/pressure regulated. This allows the plant always to provide the maximum capacity achievable with the given feed water temperature/salinity at any given time
  • All units are equipped with a fail-safe system which protects them from potentially damaging external conditions and/or operator errors
  • High pressure pumps start operation in optimum conditions because pressure builds up very progressively as the motorized pressure control valve closes slowly until it reaches its pre-determined stable position, corresponding to the set pressure in the modules


Rochem RO-Freshwater
Generator SYSTEM TYPE RO 1530 25S.
Capacity: 25 m3 /day

RO‐Plant designed for the special requirements on ships. The RO‐Plants can produce naturally pure potable water with app. 500 mg/l of remaining minerals at a seawater temperature of 25°C. The quality of the produced water will be in accordance to the latest requirements of the WHO.


The seawater will first pass the pre-filtration stage of the unit, and according to the extended limits for the wide range of SDI-value for the PF-Module-Technology up to 20 %·min-1 (Fouling/Blocking Index), only simple mechanical pre-filtration is necessary.
The pre-filtration section consists of a backwashable, multilayer sandfilter with downstream installed cartridge filter (10 µm).

Desalination Module

The PF-MODULE-TECHNOLOGY uses the latest type of membrane material, the so called TFC – Thin Film Composite of Polyamide/Polysulfone material. No chemical dosage for pH-value correction such as acid is necessary. The desalination by the PF-Module guarantees an absolutely natural process and assures that the quality of the potable water is not affected by any chemical contamination.

After passing the high-pressure pump and the pre-filters the seawater is supplied into the PF-Module, where it passes through the disc-plate stages, arranged in series, which guarantees a controlled cross-flow path of the seawater over all membrane surfaces by an optimum of hydraulic flow process.

Thirty percent of the seawater passing through (Recovery Rate) will permeate throughout the membranes as a natural high quality potable water. The other 70% of the capacity will leave the module as a concentrate containing all of rejected salts and other water impurities and will be discharged back to sea after having passed the high-pressure control valve by dropping down the pressure.


After approximately 600 to 800 hours of operation the unit demands a membrane cleaning. Cleaning is initialized by a few manual operation steps like switching of valves and filling of cleaner into the cleaning tank. The cleaning sequences are automatic controlled by the PLC.

For the cleaning procedure only harmless cleaning solutions will be used to remove fouling or other scaled deposits. The cleaning solutions belong to low class IMO-codification.

ROCHEM RO-Freshwater Generator
Capacity: 5 m³/ day potable water

Design and Construction Standards

The ROCHEM RO Fresh Water Generators are designed, fabricated and approved according to the following National and International Standards:

  • DIN – (German Industrial Standard)
  • VDE – (Association of German Electricians)
  • VDMA- (Organisation of German Mechanical Engineers)
  • IEC – International Electric Standards for Electric Motors
  • ISO – International Standards

The ROCHEM RO units are designed and constructed to fulfil the requirements of the following Classification societies:

  • Germanischer Lloyd
  • Lloyds Register of Shipping
  • American Bureau of Shipping
  • Det Norske Veritas
  • Bureau Veritas
  • RINA Certificates for high pressure hoses