An improved ASM-GDA approach to evaluate the production kinetics of loosely bound and tightly bound extracellular polymeric substances in biological phosphorus removal process

• Published in: RSC advances 2020-01, Vol.1 (5), p.2495-256
• Main Authors: Cui, Hai, Yang, Shan-Shan, Pang, Ji-Wei, Mi, Hai-Rong, Nuer, Chen-Chen, Ding, Jie
• Format: Article
• Language: English
• Subjects: Activated sludge; Algorithms; Anaerobic processes; Biological activity; Chemical oxygen demand; Chemistry; Degradation; Kinetics; Mathematical models; Organic chemistry; Parameters; Phosphorus; Phosphorus removal; Self organizing maps; Sensitivity analysis
• ISSN: 2046-2069; 2046-2069
• DOI: 10.1039/c9ra06845g

This study established an extended activated sludge model no. 2 (ASM2) for providing a new recognition of the contributions of both loosely-bound EPS (LB-EPS) and tightly-bound EPS (TB-EPS) into phosphorus (P) removal by incorporating their formation and degradation processes during the anaerobic-aerobic cycle. For determining the best-fit values for the new model parameters ( k h,TB-EPS , k h,LB-EPS , f PP,TB-EPS , and f PP,LB-EPS ) in this extended ASM2, a novel and convenient gradient descent algorithm (GDA) based ASM (ASM-GDA) method was developed. Sensitivity analysis of f PP,TB-EPS , f PP,LB-EPS , k h,TB-EPS , and k h,LB-EPS on the model target outputs of S PO 4 , X TB-EPS , X LB-EPS , and X PP proved the accuracy of the chosen parameters. Eight batch experiments conducted under different influential chemical oxygen demand (COD) and P conditions were quantitatively and qualitatively analyzed. Respectively, 9.37-9.64% and 4.17-4.29% of P removal by TB-EPS and LB-EPS were achieved. Self-Organizing Map (SOM) has shown its high performance for visualization and abstraction for exhibiting the high correlations of the influential COD/P concentrations and the P% removal by TB-EPS (and LB-EPS). Comprehensive analyses of the influences of influential COD and P concentration on the biological phosphorus removal process help us in successfully establishing the mechanism kinetics of production and degradation of P in a dynamic P biological-treatment model. An extended activated sludge model no. 2 provides a new recognition of the contributions of both loosely- and tightly-bound EPS into phosphorus removal by incorporating their formation and degradation processes during the anaerobic-aerobic cycle.