Membrane Technology for Water Purification and Wastewater Treatment

The term membrane technology is used to describe a variety of liquid filtration and separation processes that includes micro-filtration, ultra-filtration, nano-filtration and reverse osmosis. All these filtration processes have one thing in common – the use of a membrane as a major component in the separation process itself.

Typically speaking you will find a membrane used in technologies that filter water from various sources to get rid of any particulates (contaminants) in that water.

Once filtered, the water can then be used for a variety of purposes including drinking water, food technology, biotechnology and the pharmaceutical industries.

Is Membrane Technology Energy Efficient?

This membrane technology has been put to good use in many ways.

While it can perform a similar function to other separation processes including distillation, the main difference is that it does not require a heat source for this to occur.

As a result, membrane separation technologies tend to use far less energy than is the case in other similar processes.

A certain amount of energy is required in order to drive the liquid through the membrane itself. However this is far less when compared to the amount used in thermal separation methods.

Water Purification, Desalination & Wastewater Treatment

While this membrane technology can be used in a variety of industries, including the biotech, pharmaceutical and food industries, it is used extensively to help purify drinking water, desalinate salty/seawater and for the treatment of wastewater and greywater.

Water treatment, water reuse and water recycling is very important nowadays, and many industries use membrane technologies to help them recycle water they would otherwise send to waste.

By reusing and recycling contaminated water they can use it once again, thus reducing their environmental footprint with regard to water use.

Different Types of Membrane

There are all manner of different membranes that can be used when treating water in this way.

Commercial membranes are typically made from synthetic materials and are usually flat sheets or plates, spiral wound membranes, or hollow fibre membranes.

Some of the membranes will remove solids and particles that are in the water, while others are fine enough to remove bacteria and viruses.

Using the correct membranes, it is possible to turn wastewater into potable, or drinking water.

Keeping Membranes Clean & Free from Fouling

Of course, a membrane is only practical to use if it is clean, the pores are not clogged with debris and they remain free of contamination.

Membrane fouling can occur in a variety of ways… for example, the membrane can become scaled-up with insoluble salts contained in the volume of water that passes through it over time.

Particles may also block the membrane pores eventually if a membrane is being used for this purpose.

Finally, biofouling may also occur if the membrane is used to filter out organisms and bacteria.

Regular cleaning of the membranes, maintenance and replacement will need to be carried out in order to ensure the membrane facilities continue to work at their optimum capacity.

Membranes can be flushed out using air or specialist membrane cleaning chemicals, or by water itself, either going forwards or reversing it backwards through the system.

Once the membranes are clean, the process can begin again and operate at increased efficiency although performance should be continually monitored.

Monitoring Membrane Performance

One way to monitor membrane efficiency is with a silt density index (SDI) monitor which measures the fouling capacity of water in such systems.

More on Silt Density Index testing

World Class Water Management Solutions

Water Treatment Services are a leading independent UK water treatment and environmental services company offering expert water management solutions including professional SDI testing, water treatment and water hygiene services, water sampling, laboratory analysis and full support services.

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