Filtration is the most important mechanical treatment applied to water: very often, in fact, it is combined with many other chemical-physical or biological treatment processes (such as desalination/demineralization), which act on other water characteristics.

Pressure filtration systems for well water, surface water, or even wastewater are designed to remove various contaminants.

They can be manufactured in either fiberglass or carbon steel (properly sandblasted and painted). The water to be treated passes through the filter bed in co-current flow (from top to bottom) and as solids and/or contaminants deposit in the free spaces, the resistance to water flow progressively increases, and therefore the pressure drop. When the pressure drop (pressure difference between filter inlet and outlet) reaches approximately 0.7 bar, it is necessary to perform filter washing to avoid the possibility of contaminant breakthrough with the consequent decrease in treated water flow rate.

According to a predetermined schedule (based on time or filter volume), the filter media are washed with water or air. This operation is performed automatically through the opening and closing of appropriate valves, and is necessary in order to optimize the process and maintain the efficiency of the filter material over time.

The pressure filtration systems designed and manufactured by Carra Depurazioni are essentially of the following types:

– Multi-layer sand filtration

– Activated carbon filtration

– Filtration for iron and manganese removal (Iron removal filters)

The effectiveness of the filtration and/or adsorption process is directly proportional to the flow velocity of the liquid to be treated through the system, and therefore as a function of the contact time with the aforementioned filling materials. Furthermore, such timing is directly dependent on the type of liquid to be treated and must take into account the quantity of substances to be retained/adsorbed and the desired result in terms of efficiency and/or performance of the filtration system itself. Another consideration to take into account when sizing such filtration systems is also and above all the water quality objective to be achieved.

For this reason, in case of specific, particular and/or demanding applications, it is recommended to contact our Technical Department directly for custom sizing.