Reverse Osmosis & Nano Filtration
Reverse Osmosis wrongly is sometimes classed as a filter. It does filter out some contaminants but by a process of Osmosis incorporating semi permeable action. Reverse Osmosis systems work by applying a high pressure pump to a concentrated solution of unfiltered water, which can be in a form of seawater, brackish or well water, mains tap water.
The system forces the water through a semi-permeable membrane, leaving all of the dissolved salts and other substances behind. This is effectively a molecular filter to remove up to 99% of all dissolved solids or minerals within the water. This semi-permeable membrane allows water molecules to pass through whilst blocking and allowing salt molecules to pass to waste. As a pressure is applied to the concentrated side of the membrane water with smaller molecules passes through to the dilute side leaving these concentrated salts left behind as before sending to waste.
A Reverse Osmosis unit will not be used for softening water or de-chlorination even though it could do this. The supply water is usually softened and chlorine removed before treatment to allow for plant longevity and efficiency. Reverse Osmosis water is pure and may be purified further for higher quality to the pharmaceutical and food industry.
The correct choice of pre-treatment is very important as it influences the quality and quantity of the product water and above all the life span of the membranes. By not treating properly the feed water systems can experience more maintenance due to experiencing scaling and fouling from colloids or bacteria.
Nano-Filtration by membrane separation is similar to Reverse Osmosis with slightly larger holes in the membranes. Nano-Filtration, in water treatment “bridges” a gap between Ultra-Filtration and Reverse Osmosis. They are utilized for the filtration of water with low total dissolved solids (TDS) for the purposes of eradicating organic substances and softening water. It is sometimes referred to as a loose or lower rejecting RO membrane. A Nano-Filtration system lets more salt pass through than an RO membrane with the same volume with about 70% of the pressure as an RO.
Nano-Filtration is a cross flow filtration technology not a dead end filter. The pore size of the membrane is about 1 nanometer. The pressure to utilize nanofiltration is also less that Reverse Osmosis and it also removes fewer monovalent ions than RO (around 50-90%). This enables the membrane to remove hardness from water but leave the total solids content less affected. Like Reverse Osmosis, and Ultra Filtration, Nanofiltration will recover a percentage of the feed water. Most all Nano-Filtration membranes are of a spiral wound configuration.
Reverse Osmosis and Nano-Filtration plant must be supplied with de-chlorinated and softened water or dechlorinated raw water treated with an anti-scalent. Waste water can sometimes be used downstream as other use for wash down or even some processes being softened eliminating wastage.


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The full range of HydroChem Services:

Water Treatment - Industrial
We are leading supplier of Legionella compliance services, water hygiene risk assessment, water treatment, installations and maintenance.

Water Treatment - Domestic
Assessing systems that may pose a risk to exposure to legionella, including humidifiers, air washers, emergency showers and indoor ornamental fountains.

Risk assessment
Ensuring all commercial premises have a statutory duty to control the risk of legionella bacteria in water systems.

Water Hygiene
Protecting the public from hazards associated with bacteria in water systems particularly Legionella.

Chemicals
We offer an extensive range of water treatment chemicals to suit all processes and requirements.

Chemical Cleaning & Disinfections
We have dedicated teams of experienced engineers to diagnose and give site specific recommendations.

Plant & Equipment
We offer a vast range to ensure that processes are effectively operated to their maximum advantage and costs.

Remedials
After a Legionella risk assessment, it is likely that corrective or improvement works are required to bring your system up to compliance.

Mould, Air & Surface Remediation
Our protocols allow a building or site be kept clean, environmentally sound and free of contamination.

Borehole Water Treatment
We offer an extensive range of borehole water treatment options to suit all processes and requirements.

