Sludge analysis

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The sedimentation analysis , also known as slurries or slurry is designated, a mechanical separation method for quantitative determination of the fine grain proportion of a sediment sample ( Dispersitätsanalyse ). Sludge analysis is one of the methods of sedimentation analysis .

The principles on which it is based are also used in the separation of batches of substances to obtain the individual fractions , for example in the separation of gold grains and sand .


The slurry process is used when a pile (granular matter) mixed with water consists predominantly of very fine grain ("slurry grain ", grain sizes with an equivalent diameter of less than 0.063 mm). The grain fractions silt and clay contained therein as suspended matter can no longer be separated from one another by means of a sieve analysis . The different sinking speeds of the two grain fractions are used to determine the grain distribution .


In the case of the sludge analysis, the sample is stirred up in water to form a suspension and this is left to stand in a measuring cylinder . Due to the rapid sinking of the suspended matter ( sedimentation ), which varies depending on the grain size, the distribution of the grain sizes and thus the distribution of the density in the suspension changes over time. To measure the changes in the density distribution, a hydrometer is immersed in the suspension at fixed time intervals. From the immersion depths, the densities and from them the mass fractions of the grain fractions are determined using a nomogram according to Stokes' law . This results in a particle size distribution curve . Proportions greater than 0.063 mm (63 µm) are determined, depending on the proportion of the total mass, before or after the sludge analysis by wet sieving method, drying and weighing / percentage evaluation (combined sieve and sludge analysis).

Mud in micropalaeontology

Operation of a sludge plant for sub- Cretaceous fossils at the Champblanc site near the western French city of Cognac

A method of extracting microfossils is also known as sludging . These are fossils smaller than 2.0 mm that remain as sieve residue from a sediment sample . The finer sediment is washed away with running water. Eduard Peters introduced the mud process to the work of paleontology.

Sludge in Archaeobotany

In archaeobotany , slurries are used to remove charred plant remains from the sediment.

Individual evidence

  1. ^ Fritz-Nielsen Wissing, Ekkehard Herrig: Working techniques of micropalaeontology. An introduction. Enke Verlag, Stuttgart 1999, pp. 46-47.
  2. ^ Eduard Peters: My work in the service of the prehistory of southwest Germany . Veringenstadt 1946.
  3. Stefanie Jacomet, Angela Kreuz 1999, Archäobotanik: Tasks, Methods and Results of Vegetation and Agricultural History Research. UTB, ISBN 978-3825281588