Water sampling with rotating sieve filter (RoSi)

The provision of very fine or low-concentration solid particles from the aquatic environment sometimes requires very large sample volumes, for example 2 - 3 m³ wastewater treatment plant effluent or up to 6 m³ surface water for a thermoanalytical microplastic determination.

In order to convert these large sample volumes to a standard laboratory level, the solids contained in the sample must be concentrated. A principle that has proven itself in practice is the separation of solids by means of filtration or sieving. The problem with solid-liquid separation by means of sieves is the formation of a filter cake that blocks the meshes of the sieve and reduces throughput.

The core of the rotating sieve filter RoSi consists of an inclined, rotating sieve, which is continuously charged and backwashed with filtrate, which prevents the build-up of a filter cake. Here scoop samples can be applied manually or an automated feed can be set using a hose or, for suction heights> 7 m, using submersible pumps at peak flows of up to 2 l / s.

The apparatus can be used mobile, can be operated continuously over longer periods of time (> 72 hours) and enables automated sample preparation in the field with a defined lower limit of up to 5 µm - the field samples are concentrated up to a volume of 2 l.