Comparative Study of Balancing SRT by Using Modified ASM2d in Control and Operation Strategy at Full-Scale WWTP

Jakub Drewnowski,Aleksandra Szaja,Łukasz Kopeć,Grzegorz Łagód,Jacek Mąkinia,José Alonso Aguilar

doi:10.3390/w11030485

Jakub Drewnowski, Aleksandra Szaja + Show 4 more

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https://doi.org/10.3390/w11030485

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Abstract

Detailed knowledge on the composition of the influent going into the wastewater treatment system is essential for the development of a reliable computer model. In the context of WWTPs (wastewater treatment plants), the wastewater characteristics are not only important for activated sludge system modelling, but also have an impact on the appropriate control of single unit operations. The aim of this study was to evaluate the concepts of COD (chemical oxygen demand) fractionation measurement in municipal wastewater with a respirometric method in control, and modelling the biological treatment processes at WWTP using the modified Activated Sludge Model no. 2d (ASM2d) developed by Drewnowski and Makinia. The batch OUR (oxygen uptake rate) test results and COD measurements obtained at BNR plant (96,000 m3/d) in Gdansk (Poland), were compared and evaluated with the main BNR (biological nutrient removal) WWTP (144,000 m3/d) located in Malaga (Spain). Respirometric tests and COD fractionation provided the experimental database for the comparison of the wastewater characteristics and model predictions at both large WWTPs. Some parameters, such as the heterotrophic growth yield (YH) coefficient, required calibration/validation of the range (YH = 0.64 and 0.74 gCOD/gCOD for Gdańsk and Malaga WWTP, respectively) to fit the modified ASM2d. The crucial issue when dealing with the newly developed model and proposed wastewater characterization for both study plants were extremely low and high values of the XS/XI ratio, which can be used to control full-scale WWTP and balance the solid retention time (SRT) in activated sludge systems.

Highlights

The introduction of activated sludge modelling into the engineering practice was a breakthrough in wastewater treatment, which resulted in a significant improvement of the design, operation, and monitoring of many wastewater treatment plants (WWTPs) [1,2,3]
The aim of this study was to evaluate the concepts of COD fractionation measurement in municipal wastewater with a respirometric method in the control and modelling of biological treatment processes at WWTP using the modified Activated Sludge Model no. 2d (ASM2d) developed by Drewnowski and Makinia [20]
This study showed that the matter of improving the reliability of the solid retention time (SRT) determination is important for the mathematical modelling of activated sludge (AS) systems, in addition to design, operation, and control of AS systems, especially with BNR WWTP

Summary

Introduction

The introduction of activated sludge modelling into the engineering practice was a breakthrough in wastewater treatment, which resulted in a significant improvement of the design, operation, and monitoring of many wastewater treatment plants (WWTPs) [1,2,3]. The division of chemical oxygen demand into fractions is the main parameter that describes the organic matter presented in wastewater [13,14]. The non-biodegradable fractions are biologically inert and are transferred through the activated sludge system without any significant modification. The concentration of inert soluble organic matter (SI ) does not change during the treatment. The slowly biodegradable fraction (XS ) as well as the rapidly hydrolysable COD fraction (XH ), are mainly composed of particulates, colloidal and complex organic molecules, which have to be hydrolysed by extracellular enzymes of bacteria. More complex division of organic substrate has been described in the modified Activated Sludge Model no

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