Reverse Osmosis

Reverse osmosis (RO) is currently the most important technology worldwide for desalinating seawater and brackish water. The process pushes saltwater through a semi permeable membrane at high pressure. Water can pass through, while salt and other substances remain behind. The quality is high, the process is reliable, and plants can be scaled from small units to large projects. For many regions, reverse osmosis is the most efficient way to provide large quantities of clean drinking water.

Umkehrosmose

Operation

A reverse osmosis plant requires continuous care and technical expertise. Filters must be replaced, membranes cleaned and the dosing against deposits precisely controlled. Pumps, valves and sensors need regular maintenance to keep pressure and water quality stable. The control system must run reliably, and errors must be detected and corrected. In addition, chemicals, spare parts and a strategy for managing the brine are needed. Operation requires trained specialists and causes ongoing costs that can be significant depending on water quality and plant size.

Sustainability

Reverse osmosis requires high initial effort (manufacturing and construction) and produces salt brine. In seawater RO typically 35 to 50 percent of the intake becomes drinking water.
From 2 to 3 liters of seawater about 1 liter of drinking water is produced, the rest is returned as concentrated brine. If this brine is discharged without sufficient dilution the increased salt content can strongly impact local marine organisms.
Power demand is often around 3 to 5 kWh per m³ of drinking water.
RO becomes environmentally acceptable through efficient plants, renewable energy and brine discharge that protects local ecosystems.