Filtration technologies

The proven foundation for reliable water treatment

Filtration is a versatile and robust separation technique that removes suspended solids, fine particles and specific contaminants from water streams. With the right choice between mechanical filters, sand filters or activated carbon filters, filtration is a key link in industrial water treatment. It protects downstream processes, increases the operational reliability of installations and supports efficient water reuse, further purification or safe discharge.

What is it?

What is filtration and how does it work?

Filtration is a widely used technique for removing unwanted substances from water. The water is passed through a filter medium that blocks or retains contaminants.

How a filter works depends on the filter material chosen. Conventional filters physically retain particles, whereas an activated carbon filter mainly binds certain substances through adsorption. This means filtration can be used as pre-treatment, as post-treatment or as part of a complete water treatment plant.

By choosing the right filtration technique, the water is brought to the quality required for reuse, discharge or further treatment.

When should you choose filtration?

A filtration system is often the most robust and cost-effective way to protect your process water and polish your wastewater without complex chemical management.

Filtration is used when water contains suspended solids, particles or specific contaminants that affect water quality or could disrupt further treatment. It is often an important step in the pre-treatment of process water, wastewater or rainwater.
Compared with other separation techniques, this technology uses little energy and few chemicals.

Choose filtration when you want to:

remove suspended solids or fine particles from water;
protect pipework, pumps, membranes or other installations;
reduce the load on a subsequent treatment step;
reduce odour, colour, taste or organic compounds;
make water suitable for reuse, discharge or further treatment.

A broad spectrum of filtration technologies

Depending on the water quality and the application, PCA Water can provide various filtration technologies.

Mechanical filters

A mechanical filter is a filtration technique that removes solid particles from water based on particle size. The principle is similar to that of a sieve: water flows through a filter medium with fine openings, retaining larger particles and suspended solids while letting the filtered water pass through.

Depending on the application, filtration can range from relatively coarse particle removal to very small pore sizes. Ultrafiltration (UF) is one example, using membranes with very small pores to also separate out fine suspended particles, colloids and micro-organisms.

Depending on the application, either a manual or an automatic filter solution can be chosen.

With a manual filter, the filter element is periodically replaced or cleaned by an operator. This solution is suitable for applications with limited fouling, lower flow rates or installations where maintenance can easily be scheduled.

With an automatic filter, accumulated dirt is removed automatically without interrupting the process. This is done, for example, by backwashing, scraping or a self-cleaning filter system. Automatic filters minimise downtime, ensure a constant filtration capacity and are particularly suitable for continuous industrial processes or water streams with a higher solids load.

Sand filter

A sand filter uses a filter bed made up of different types of filter sand. Thanks to the small gaps between the fine filter grains, suspended solids, sludge and other particles are mechanically retained as the water flows through the filter.

To combine optimum filtration with a limited pressure drop, the filter bed is usually built up from several layers with different grain sizes.

During the filtration process, suspended solids gradually build up in the filter bed. To maintain filter performance, the installation is periodically cleaned by backwashing. Water (optionally combined with air) is sent through the filter in the reverse direction, so that the accumulated dirt is loosened and flushed away.

Activated carbon filter

An activated carbon filter works on the principle of adsorption: dissolved substances attach themselves to the porous surface of the activated carbon.

For efficient operation, it is essential that the water to be treated is sufficiently free of suspended solids and sludge particles beforehand. If the water still contains too many particles, the activated carbon will clog up more quickly. This leads to a higher differential pressure, channelling and a sharp reduction in adsorption capacity. That is why activated carbon filtration is usually preceded by a mechanical filtration step, such as a sand or cartridge filter.

Over time, the activated carbon becomes saturated and its uptake capacity decreases. The activated carbon must then be replaced or reactivated.

In which applications are filtration technologies used?

Industrial water treatment

Cartridge filters and sand filters are used in industrial water treatment as pre-filters for membrane systems or to protect installations further along the treatment process.

Drinking water

In the drinking water sector, activated carbon filters play an important role in removing unwanted organic substances as well as odour and taste compounds.

Polishing with activated carbon

In industrial water treatment, activated carbon is often used as a polishing step after biological or physico-chemical treatment to further reduce the residual organic load.

FAQ: frequently asked questions about filtration technologies

Does an activated carbon filter also need to be backwashed?

Yes. An activated carbon filter is backwashed periodically to keep the filter bed working properly. During backwashing, the filter bed is redistributed evenly and preferential flow channels are avoided, so that the water continues to flow evenly through the activated carbon.

However, backwashing does not regenerate the activated carbon or remove the adsorbed contaminants. Over time, the activated carbon becomes saturated and its adsorption capacity decreases. At that point, the activated carbon must be replaced or reactivated externally in a specialised facility.

What types of mechanical filters are there?

There are various types of mechanical filters, depending on the application, the required filtration level and the nature of the contaminants in the water. The most commonly used mechanical filters include cartridge filters, bag filters, candle filters, sand filters, drum filters, strainers or basket filters, and self-cleaning filters.

How do I determine the mesh size of my filter?

The mesh size or micron rating of a filter is determined by the size of the particles to be removed from the water. The smaller the pore size, the finer the particles that are retained. However, a finer filter also leads more quickly to pressure loss or clogging.

When choosing the right micron rating, PCA Water takes into account factors such as:

the particle size of the contaminants;
the amount of suspended solids in the water;
the required filtration level;
the flow rate through the installation;
the risk of clogging;
the sensitivity of pumps, membranes or other downstream equipment.

In practice, the micron rating is often determined on the basis of a water analysis, practical experience and the requirements of the downstream process. This strikes a balance between sufficiently fine filtration and reliable operation of the installation.

PCA Water helps you select the right filter fineness, tailored to your water quality and application.

Experience the difference with PCA Water.

Would you like to know whether an advanced filtration system could optimise your process? Contact us for a technical analysis by our engineers.

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