Salher relies on reverse osmosis drinking water treatment plants for seasonal demands

Aug 10, 2022

An increasing number of municipalities and entities rely on membrane technology in water treatment, in order to obtain higher quality permeate water. Salher offers an extensive catalogue of compact drinking water treatment plants using reverse osmosis membranes.

The reverse osmosis system is a water purification technique with multiple applications – desalination, purification of drinking water, obtaining ultrapure water, treatment of urban and industrial wastewater – throughout all types of areas, which continues growing at the same time as the number of water treatment facilities incorporating it is increasing. Among these applications, its installation as a DWTP is growing in small and medium-sized towns.

However, reverse osmosis technology applied to residential service faces a handicap for which it is not prepared a priori due to the way it works: seasonality. In recent years, the abandonment of villages that caused the rural exodus in many areas is being reversed by people who, in search of a better quality of life, are establishing their second homes in these areas.

This population turnover complicates the design of drinking water treatment plants for supplying these municipalities, with the capacity to adapt to seasonal and discontinuous demand being one of the fundamental requirements for their success. In this sense, and given the need for continuous operation of reverse osmosis technology, its application in this environment seems to be incompatible.

Aware of this, Salher has developed reverse osmosis plants with isolated operations by modules and with hibernation protocols that allow the same plant to operate at several different flow rates depending on demand, without causing premature fouling and shortening of the useful life of the membranes.

Planta potabilizadora Salher para el aeropuerto de Alicante-Elche

Compact reverse osmosis plants

Salher’s reverse osmosis plants, which are suitable for seasonal demands, have several working scenarios in which they can operate, depending on the instantaneous demand and, therefore, on the level of water detected in the treated water tank that supplies the municipality concerned. When the demand for water decreases due to lower consumption, the treated water production regime will also be reduced. This implies a change in the working conditions of the plant towards a scenario where several reverse osmosis membranes are isolated.

For these variables to work, it is essential to have made a detailed prior study of the demand and its seasonal regime, which will allow the engineers in charge of the plant design to select the equipment that best adapts to these records, both in terms of the design capacity of the pumps and the possible configurations of reverse osmosis and the lamination volumes of the tanks that come into play in the process.

Independent cleaning in stages and the ability to adapt to different demands depending on the work scenario are essential for the correct design of flushing and CIP membrane cleaning. A common feature of Salher’s treatment plants is the importance given to preventive maintenance, an essential factor in the case of reverse osmosis technology. Thus, the use of permeate water, the cleaning times, the chemicals used and the set-point values for the activation of the cleaning process are established in great detail and in a way that is specific to each plant.

A unique aspect of this process of adapting to seasonal demand is the definition of a hibernation protocol that allows the plant to operate in a ‘low demand’ mode for extended periods of time if necessary. This protocol consists in preserving the membranes that are not operating by soaking them in a preservative product. Likewise, their restoration back to full capacity operation is carefully designed to ensure that the process is carried out safely and without any interruption in the production of water and high quality water at any time.

Salher has extensive experience in designing and installing reverse osmosis plants, from which some significant advantages can be drawn:

  • Detailed design and reliability.
  • Maximum water quality for human consumption, irrigation and industrial uses.
  • High retention of pollutants, reaching up to 99%.
  • Homogeneity in the standardised values.
  • Small and compact size.
  • Easy installation and operation.
  • Low maintenance cost.

Salher engineers adapt to the needs of each client to ensure a constant quality of treated water and reduced investment and operating costs (CAPEX and OPEX). Thanks to all this, today we can talk about Salher as a reference company in reverse osmosis systems.

Salher Newsletter


Latest news


Salher Products

Designed and developed to meet all the requirements in water treatments.



Project and Design

Engineering development and projects management.


Production of GFRP, polypropylene and steel equipment.
Assembly of modular equipment and integration in civil works.


Selection of equipment and instrumentation to provide an integral water treatment solution.


Technical assistance in the electromechanical and electrical assembly of every water treatment plant.


Post-installation control service by a qualified technical staff.

Courses & documentary support

Practical training and delivery of manuals of operation, commissioning and maintenance.

Carrera Toledana, 33. Arganda del Rey. Madrid 28500. Spain.

+34 91 870 00 15

Spain / +34 91 870 00 15

Malaysia / +60 102 452 108

Mexico / +52 55 5081 8437

Peru / +51 620 0722

Paraguay / +595 981 252 845

Poland / +48 22 737 24 95

Portugal / +351 234 795 821

Engineering – Wastewater treatment – Purification – Liquid/solids separation equipment for industrial and municipal process applications – Surface water – Groundwater – Water Reuse – Drinking Water – Hydrocarbon and Oil Water Separation

Privacy Policy