Abstract
A laboratory scale automation system for the extended aeration process was installed to study the effects of DO controlling and intermittent aeration on energy saving and nitrogen removal. ORP reaches to the peak (P 1) when nitrification finishes in the constant DO condition. The ORP peak can be used as the indicator for finishing aeration. The ORP inflection point appears at the end of denitrification is already known as ‘the nitrate knee’. Therefore, optimum DO control for nitrogen removal can be realized, by detecting the both inflection points on the ORP curve.
Especially, in the conditions showing both of peak and nitrate knee on the ORP curves, the average T-N removal rate were kept over 90%.
Treated water qualities (T-N, BOD, COD, TOC) could be kept stable ever on condition that the input load varied largely.
Farther more, the energy for aeration could be largely saved using this treatment system.
