Oxygen transfer rate estimation in oxidation ditches from clean water measurements

Standard methods for the determination of oxygen transfer rate are based on assumptions that are not valid for oxidation ditches. This paper presents a realistic and simple new method to be used in the estimation of oxygen tr ansfer rate in oxidation ditches from clean water measurements. The new met hod uses a loop-of-CSTRs model. which can he easily incorporated within con trol algorithms. for modelling oxidation ditches. Further. this method assu mes zero oxygen transfer rates (K(L)a) in the unaerated CSTRs. Application of a formal estimation procedure to real data revealed that the aeration co nstant (k = K(L)aV(A).. where V-A is the volume of the aerated CSTR) can be determined significantly more accurately than K(L)a and Cb Therefore. the new method estimates X instead of K(L)a. From application to real data, thi s method proved to be more accurate than the commonly used Dutch standard m ethod (STORA. 1980). (C) 2001 Elsevier Science Ltd. All rights reserved.