Measurement using cascades and O2-Sensor
Similar to the working principle of a biological treatment plant, in this WWTP simulation, the sewage is mixed with activated sludge under aeration and continuously led through the drain cascade. On leaving the reactor cascade the remaining oxygen will be determined with the O2 sensor, whereby the volumes of waste water, activated sludge and air are specifically defined and monitored. With this method it is important to use the plants-own biomass to simulate the real biology of the particular waste water treatment plant. Hence, the measurement results have specific relevance relating to the WWTP and its unique properties.
The Bio Monitor regulates not only the optimal control of the oxygen input to the activated sludge reactors of the WWTP, but monitors the incoming contaminations of the WWTP’s influent. This enables the operator to even out possible peak pollutions, thereby maintaining aeration at a regulated level, as usually it is these peak pollutions which cause additional aeration, which in turn is energy consuming and expensive.
BOD determination by O2-Electrode
Common BOD analyzers allow a determination within 10 to 30 minutes, whereby short-term measurements of the oxygen consumption through O2 electrodes dominate. However, as oxygen is hardly soluble in water, very often low measurement results are found, which then need to be extrapolated. Essentially, this method really only is suitable in determining very easily degradable substances.