New sensor based on pH effect of denitrification process

By observing the acid/base addition rate of a pH controller that centrals the pH in a sample of activated sludge mixed liquor at a set point, the proton dynamics of the reactions taking place in the sample can be monitored. Using this technique, the progress of the denitrification reaction car! be monitored, and. the amount of carbon required for the complete denitrification of the nitrate present in the sample can be determined. A new sensor based on this principle is able to measure on-line the nitrate concentration, the denitrification capacity, and the denitrification stoichiometry without the need for any sample pretreatment. A prototype has successfully been implemented on a full-scale wastewater-treatment plant to automatically control the dosage of an external carbon source.