The use of the Barcroft differential manometer in the estimation of the oxygen absorption of sewage
Walter Reginald Wooldridge, A. F. B. Standfast · Biochemical Journal · 1936
OuR earlier investigations on the purification of sewage by the activated sludge process [Wooldridge and Standfast, 1932; 1933; Wooldridge, 1933] led us to two main conclusions.Firstly, we concluded that probably the most important factor in sewage purification was a series of catalysed oxidation-reduction reactions determined by bacterial enzymes, present in either living or dead bacterial cells, or liberated by them into the fluid of the reacting system.Secondly we formed the opinion that neither of the two tests investigated was entirely satisfactory foil use in a systematic study of the conditions influencing the purification of sewage by the activated sludge process; e.g. the technique for the determination of B.O.D. necessitates the incubation of many portions of the same sample for various periods oftime.Considerable improvement could clearly be effected if the progress of oxygen absorption could be followed continuously on one sample.With this object in view experiments have been carried out on the measurement of the rate of oxidation of sewage in a Barcroft micro-respirometer.