Respirometry for determination of the influents S_S-concentration

A method is presented for determining influent readily biodegradable substrate concentration (S_S). The method is based on three different respiration rates, which can be measured with a continuous respiration meter which is operated in a cyclic way. Within the respiration meter nitrification is inhibited through the addition of ATU. Simulations were used to develop the respirometry set-up and decide upon the experimental design. The method was tested as part of a large measurement programme executed at a full-scale plant.

The proposed respirometry set-up has been shown to be suitable for a semi-on-line determination of an influent S_S which is fully based on the IAWQ #1 vision of the activated sludge process. The Y_H and the K_S play a major role in the principle, and should be measured directly from the process.