Forward osmosis delivers nontoxic pretreatment for RO desalination

Voltek’s forward osmosis system improves the energy efficiency of reverse osmosis by effectively pretreating feedwater for impurities and algal blooms, without adding foreign chemicals such as biocides, scale and corrosion inhibitors into the environment.

Voltek’s FO system pretreats feedwater containing high organics like tropical seawater or water from an anaerobic digester. A non-fouling, high osmotic pressure brine solution draws feedwater through a membrane, thereby diluting the brine. This pretreated brine is then fed into a high pressure RO system with a high recovery rate, generating pure water while the brine is sent back to the FO system in a closed loop. The waste from this system consists only of the organic and inorganic constituents of the feedwater, in a concentrated form.

How forward osmosis works

Forward osmosis (FO) is the process in nature by which plants hydrate. Osmotic pressure causes water to naturally flow through a semi permeable membrane, from areas of low solute concentration toward higher concentration. In our FO pretreatment systems, water flows towards a high salinity brine solution, filtering out organic materials in the process, without applying hydraulic pressure or toxic biocides.

Overcoming the limits of reverse osmosis

Desalination by reverse osmosis is an energy intensive method that uses hydraulic pressure to push water through a membrane, from high salinity to low salinity. Traditional RO systems require extensive pretreatment of feedwater to remove contaminants that foul the system, which is especially difficult in the presence of algal blooms. This pretreatment increases cost, lowers system pressure and performance, and introduces biocides and other chemicals to the concentrated brine discharge, which damage marine life.

Voltek’s FO pretreatment system helps to optimize RO desalination without relying on toxic chemicals.

Organic waste to biogas

Voltek’s Forward Osmosis system makes it affordable to convert sewage and industrial waste streams to biogas, including textile dyeing wastes, tannery wastes, and food waste. The system removes water from waste streams and concentrates organic fractions without destroying them. The resulting concentrate significantly improves the effectiveness of anaerobic digestion systems for converting organic waste to biogas.