Berkefeld filter

Berkefeld TWA 6 with a filter capacity of 6 m³ / h.

The Berkefeld filter is a system for water treatment using a precoat filter . The filter invented by Wilhelm Berkefeld in 1891 was a hollow cylinder made of porcelain with filter candles made of burnt kieselguhr . Filters of this type were first successful in 1892 cholera - epidemic used in Hamburg.

To this day, filter systems are manufactured using the process invented by Wilhelm Berkefeld, albeit with modern materials. Due to their robustness, the filters are particularly popular in international disaster relief. They are used, among other things, in the Emergency Response Units of the international Red Cross or the EU civil protection mechanism .

function

Filter dome from the side

The systems clean the water with the help of a precoat filter. This filter consists of Berkesil, a granulate mixture of sand and activated carbon, which is manufactured and sold by Berkefeld. At the beginning of the cleaning process, this granulate is introduced into the filter by being pumped through the filter dome together with the raw water to be cleaned . The dome with valves is switched into a circuit with a pump and this is operated at the slowest speed. In the filter dome there are several filter candles , cylindrical tubes made of a close-meshed metal grid, on which the granulate is applied and forms a so-called filter cake. This process is also known as "alluvial". When the filter cake is completely built up, the granulate surrounds the filter candles and thus forms the actual filter.

Now the circuit is opened and the raw water can be filtered and collected in a pure water tank. All particles and suspended matter get caught in the filter cake and form an increasingly thick layer there until they completely clog the filter. Once this has happened, the filter must be backwashed. Clean water is pumped backwards through the filter, so that it breaks off the filter cake and dirt from the filter candles. This dirt is discarded and a new filter cake has to be built up for further filtering.

How much water can be filtered in such a cycle depends on the degree of pollution of the raw water. In order to get the water as pure as possible and to achieve a high filter capacity, the water is pretreated in basins. Chlorine to kill bacteria and a flocculant are added to the raw water. This causes the suspended solids in the water to clump together, which then sink to the bottom of the pool due to their higher weight. In order not to suck in these dirt particles when pumping, the water is sucked off just below the surface of the water.

history

Wilhelm Berkefeld founded the Berkefeld-Filter company in Celle in 1892 , which still produces systems for process water treatment and drinking water treatment for industry, building technology, municipalities, armies and disaster control organizations all over the world. The product range extends from complex industrial systems to mobile filter systems (containers, vehicle installations, trailers) to small hand-operated filters and drip filters for home use. Technically, the mobile systems for drinking water production are offered according to the principle of precoat filtration, reverse osmosis and ceramic ultrafiltration .

The company was family-owned until 1978 and then became part of the SIHI Group (Siemen & Hinsch) from Itzehoe. Berkefeld has been part of the Veolia Water Group since 2004 and then traded as ELGA Berkefeld GmbH , and from 2009 as VWS Deutschland GmbH . Since 2015 the individual parts of the company have been renamed Veolia Water Technologies Deutschland GmbH . The company currently has around 500 employees and further locations in Bremen , Ratingen ( North Rhine-Westphalia ), Crailsheim ( Baden-Württemberg ), Leipzig ( Saxony ) and Bayreuth ( Bavaria ). Today the company is based at Lückenweg 5 in Celle ( Lower Saxony ).

Company filters
Berkefeld TWA 6
Water filter (20th century) Insert with three filter candles made of burnt diatomaceous earth
Drop filter around 1920
Portable field filter (army filter) 1940s
The company's historic buildings are now part of the “Berkefeld residential park” on Wittinger Strasse in Celle