Abstract: The contents of a liquid medium are determined using a light source and an optical detector, for example a spectrometer. A longitudinally displaceable piston sucks the medium into a cylindrical glass measuring chamber and evacuates the liquid from the chamber. At least one measuring beam is directed through the medium, and at least one reference beam is directed outside the medium. The piston has cleaning/sealing rings mounted on its outer periphery which rub against an inner surface of the glass measuring chamber as the piston travels, to clean the surface.

Abstract: In order to determine the biological oxygen demand of sewage, a sample of sewage is taken into a reaction vessel in which there is a biological bath which is kept moving turbulently by an agitator. An oxygen probe measure the oxygen consumption per unit time. After each measuring cycle the reaction vessel is rinsed with diluting water and is then ready for another measuring cycle. The reaction vessel penetrates into the sewage to be tested. The sewage sample enters the reaction vessel via an aperture.

Abstract: To analyze the oxidizable substances, for example the chemical oxygen demand (COD), contained in an aqueous sample liquid, for example sewage water, the aqueous sample liquid is diluted with dilution water and fed into a reaction container where it is mixed with ozone from an ozone generating device. After passing through a second reaction container, for example a tubular reactor, the sample liquid reaches an ozonometer appliance. Ozone being added continuously, the ratio of sample liquid to dilution water of the mixture is regulated in such a manner that the residual ozone content measured by the ozonometer appliance remains constant at a predetermined level. The ratio of sample liquid to dilution water of the mixture required to maintain the reading on the ozonometer at the predetermined level is used to determine oxidizable substances contained in the water, in particular COD.

Abstract: A process and apparatus for measuring the degree of pollution, the degradableness, and the level of toxicity of aqueous liquids, for example, effluent. A partial stream is withdrawn from the liquid undergoing examination and diluted with biologically neutral water. The diluted partial stream is oxygenated and continuously flows through a biological bath in a reaction vessel having a constant living mass. The dilution of the partial stream is regulated in such a manner through measurement of the oxygen content upstream and downstream of the reaction vessel, that with constant volume flow through the reaction vessel, the difference between the measurement values obtained remains essentially constant at a predetermined value, so that the amount of dilution serves for the indication of the level of pollution. Additional reaction vessels connected in parallel or in series with the first reaction vessel and having associated oxygen electrodes allows measurement of the toxicity and degradableness of the pollution.