Methods and devices for measuring the biologically active sludge content in aqueous solutions, e.g. activated sludge

摘要

A part-stream of the activated sludge to be investigated in sewage treatment plants is removed, aerated with oxygen and continuously passed through a reaction tank, and the oxygen content before entry into the reaction tank and its residual oxygen content after leaving the tank are measured. The part-stream is diluted so that the measured difference in the oxygen content remains essentially constant. The degree of dilution then serves to indicate the biologically active sludge content. In a second variant of the method, the dilution ratio is altered stepwise when the measured oxygen difference is above or below a limiting value. With a regionally constant dilution, the measured difference in the oxygen content then serves to indicate the biologically active sludge content.