Freshwater
A desalination plant removes salt and other unwanted substances from seawater or brackish water to produce freshwater for various uses. There are several methods of desalination, the most common being reverse osmosis.
RO Process Overview
Reverse osmosis forces water through a membrane that allows only water molecules to pass while retaining salt and other impurities. High pressure is applied to the feedwater to push it through the membrane, producing a purified permeate on the other side while salts and contaminants remain concentrated on the feed side.
Feedwater Pretreatment
Before membrane desalination, the feedwater must be free of chlorine, iron, aluminum, silica, particles, organic and biological contaminants, etc. Raw water is therefore commonly pretreated to reduce solids and other impurities that could damage membranes, clog piping, or harm the high‑pressure pump.
High-Pressure Pumping
RO systems require pressure to operate, so a feed pump raises the raw water pressure before it enters the filters. The water then passes through a finer filter to remove smaller particles and into a high‑pressure pump, which increases the pressure above the osmotic pressure before the water is desalinated in the membranes.
Permeate and Brine Handling
After the RO module the flow splits into two streams: permeate (desalinated water) and concentrate (brine). The brine is typically discharged to drain. The permeate passes through a conductivity cell; if conductivity is too high, the water is automatically diverted to drain via a 3‑way solenoid valve.
How We Can Help
Water Analysis & Treatment Design
Enwa supports customers with desalination by starting with a professional water analysis—except for West Coast and Baltic Sea water we sample your borewell, dug well or surface water and have it tested by an accredited independent laboratory. Based on the results we recommend the appropriate treatment train and supply reverse‑osmosis desalination systems tailored to your needs.
Turnkey RO Systems & Services
We deliver turnkey and standard RO plants for producing drinking and technical water from seawater and brackish sources for buildings, boats and ships, residential platforms, drilling rigs and industrial sites. Our projects cover local Swedish markets (Baltic Sea, Stockholm archipelago, Öland, West Coast, Skåne, Norrland) and international installations. Services include system design, supply, installation, commissioning and site‑specific customization to ensure reliable, compliant desalination.
