Siemens Aktiengesellschaft

Christian Vandenbossche

Jacky Vanhumbeeck

Laurent Danneels

An automated analysis process and apparatus for analyzing the amount of dispersed water-immiscible solid organic substances in sewage water whereby a precise sample of sewage is taken from a sewage source, admixed with various reagent solutions, including a K.sub.2 Cr.sub.2 O.sub.7 --solution under heat-time conditions so that a reaction occurs between the sewage and the reagent and all of the organic substance in the sample are oxidized while simultaneously at least some Cr.sup.+6 --ions are reduced to Cr.sup.+3 --ions. During this oxidation-reduction reaction and at a location remote therefrom, a precise amount of Fe.sup.+2 --ions is generated within an aqueous acidic Fe.sup.+3 --ion containing solution via a coulometric reduction process. Thereafter, the reacted sewage-reagent solution is admixed and reacted with the so-generated Fe.sup.+2, Fe.sup.+3 --ion containing solution so that any residual Cr.sup.+6 --ions in the sewage-reagent solution are reduced to Cr.sup.+3 --ions and at least some Fe.sup.+2 --ions remain. By biamperometrically titrating the resultant Fe.sup.+2 --ion containing solution with a standardized Cr.sup.+6 -- ion containing solution, the precise amount of Fe.sup.+2 --ions within the titrated solution is determined and this provides an indirect indication of the amount of organic substances within the sewage sample. Pneumatic, hydraulic and electrical circuits actuate the various steps and are themselves actuated and controlled by a master control means, such as preprogrammed computer means, which also computationally integrates data from the overall process and automatically determines the amount of organic substances in the samples under analysis.

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Zwijnaarde, Belgium

Christian Vandenbossche