Comparative sludge volume

The sedimentation process of activated sludge in the measuring cylinder corresponds to the behaviour of the sludge in the secondary settling tank in treatment plants and allows you to draw conclusions regarding the danger of the sludge output.

Dry matter content

The dry matter content of activated sludge is the weight proportion of solid matter in the sample and a measure for the active biomass it contains. To determine the dry matter content, the sample is filtered and then dried. To speed up the filtering process, it is carried out using negative pressure. The samples are dried at 105°C for two hours.

Biochemical Oxygen Demand (BOD)

In order to measure the biochemical oxygen demand, a defined quantity of sample material is poured into a 500 ml bottle and sealed. The microorganisms contained in the sample consume oxygen and give off carbon dioxide. The carbon dioxide reacts with the sodium hydroxide pellets to form sodium carbonate and water. The resulting drop in pressure is measured over five days.