Dead-End-Filtration

In dead-end filtration refers to the classic form of filtration (as in coffee filter). It is used mostly for flat membranes, but also becoming more common in hollow fiber applications. The contrast is formed by the cross-flow operation ( cross-flow filtration).

Principle

In the dead-end filtration, a feed stream to minimize the compaction of the retained substances, having a low pressure as possible ( in water treatment by means of UF membranes about 1 bar ), is pumped against the membrane. With the constant outflow of permeate a filter cake ( top layer or fouling) or a concentration gradient (concentration polarization ) from the separated solid particles on the membrane accumulates. The filter cake increases filtration resistance, and thus the pressure drop across the membrane. He must, depending on the feed composition at regular intervals by backwashing (Back pumps already separated medium ) and dry-cleaning removed and the filter element are thus regenerated.

Areas of application

Preferred areas are areas in which to be reckoned with low particle volume or lower concentration gradient. Through the permanent flow onto the feed, the permeate flow decreases steadily and it is given by the backwashing a " saw-tooth " in the filtrate. A major significance of the dead-end filtration in water treatment, but also in many other areas of membrane technology:

• Wastewater treatment
• (MBR)
• Biochemical Engineering

In the swimming pool all treatment Ultrafiltration in Dead -end to operate for the Spülabwasseraufbereitung it is manufacturer specific, if dead-end or cross-flow filtration is employed.

Economy

Characteristic features of the dead-end filtration technology are the ongoing drops in production and product loss by the backwash. The resulting with the use of cleaning detergents or their disposal and storage are also disadvantageous.

Despite certain advantages of the cross-flow filtration this is still very energy consuming. A large proportion of funds invested in the promotion of the feed energy is lost through the retentate. Therefore, at the points where it can be waived, increasingly resorted to the dead-end filtration. For the dead-end filtration is also suggested that it is very simple, and the filtration operation can be carried out by lower qualified personnel.