A.A.A. Abusam

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 transfer rate in oxidation ditches from clean water measurements. The new method uses a loop-of-CSTRs model, which can be easily incorporated within control algorithms, for modelling oxidation ditches. Further, this method assumes zero oxygen transfer rates (KLa) in the unaerated CSTRs. Application of a formal estimation procedure to real data revealed that the aeration constant (k = KLaVA, where VA is the volume of the aerated CSTR) can be determined significantly more accurately than KLa and VA. Therefore, the new method estimates k instead of KLa. From application to real data, this method proved to be more accurate than the commonly used Dutch standard method (STORA, 1980).

Benchmarking procedure for full-scale activated sludge plants

Abstract To enhance development and acceptance of new control strategies, a standard simulation benchmarking methodology to evaluate the performance of wastewater treatment plants has recently been proposed. The proposed methodology is, however, for a typical plant and that works under typical loading and environmental conditions. Thus, benchmarking a full-scale plant working under different situations is still a problem that needs to be solved. This paper proposes a data based approach to benchmark any specific full-scale activated sludge plant used for carbon and nitrogen removal and using real design, operational and performance data. The advantage of the proposed approach over the “one-typical-plant” approach, is that it takes into account the very specific design and operational characteristics of the plant that will be benchmarked. A real-world illustrative example is also presented in this paper.

Forward and backward uncertainty propagation : an oxidation ditch modelling example

In the field of water technology, forward uncertainty propagation is frequently used, whereas backward uncertainty propagation is rarely used. In forward uncertainty analysis, one moves from a given (or assumed) parameter subspace towards the corresponding distribution of the output or objective function. However, in the backward uncertainty propagation, one moves in the reverse direction, from the distribution function towards the parameter subspace. Backward uncertainty propagation, which is a generalisation of parameter estimation error analysis, gives information essential for designing experimental or monitoring programmes, and for tighter bounding of parameter uncertainty intervals. The procedure of carrying out backward uncertainty propagation is illustrated in this technical note by working example for an oxidation ditch wastewater treatment plant. Results obtained have demonstrated that essential information can be achieved by carrying out backward uncertainty propagation analysis.

A PROCEDURE FOR BENCHMARKING SPECIFIC FULL-SCALE ACTIVATED SLUDGE PLANTS USED FOR CARBON AND NITROGEN REMOVAL

Abstract To enhance development and acceptance of new control strategies, a standard simulation benchmarking methodology to evaluate the performance of wastewater treatment plants has recently been proposed. The proposed methodology is, however, for a typical plant and typical loading and environmental conditions. Thus, benchmarking a full-scale plant working under different situations is still a problem that needs to be solved. This paper proposes a realistic approach to benchmark specific full-scale activated sludge plants used for carbon and nitrogen removal, based on real design, operational and performance data. An illustrative example is also presented in this paper.