title: Modelling the metabolic shift of polyphosphate-accumulating organisms.
abstract: Enhanced biological phosphorus removal (EBPR) is one of the most important methods of phosphorus removal in municipal wastewater treatment plants, having been described by different modelling approaches. In this process, the PAOs (polyphosphate accumulating organisms) and GAOs (glycogen accumulating organisms) compete for volatile fatty acids uptake under anaerobic conditions. Recent studies have revealed that the metabolic pathways used by PAOs in order to obtain the energy and the reducing power needed for polyhydroxyalkanoates synthesis could change depending on the amount of polyphosphate stored in the cells. The model presented in this paper extends beyond previously developed metabolic models by including the ability of PAO to change their metabolic pathways according to the content of poly-P available. The processes of the PAO metabolic model were adapted to new formulations enabling the change from P-driven VFA uptake to glycogen-driven VFA uptake using the same process equations. The stoichiometric parameters were changed from a typical PAO coefficient to a typical GAO coefficient depending on the internal poly-P with Monod-type expressions. The model was calibrated and validated with seven experiments under different internal poly-P concentrations, showing the ability to correctly represent the PAO metabolic shift at low poly-P concentrations. The sensitivity and error analysis showed that the model is robust and has the ability to describe satisfactorily the change from one metabolic pathway to the other one, thereby encompassing a wider range of process conditions found in EBPR plants.
authors.affiliation: Instituto de Ingeniería del Agua y Medio Ambiente, Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain. Electronic address: breacju@posgrado.upv.es.
authors.forename: B
authors.initials: B
authors.lastname: Acevedo
authors.affiliation: Departamento de Ingeniería Química, Universidad de Valencia, Doctor Moliner, 50, 46100 Burjassot, Valencia, Spain. Electronic address: luis-borras-falomir@uv.es.
authors.forename: L
authors.initials: L
authors.lastname: Borrás
authors.affiliation: REQUIMTE/CQFB, Chemistry Department, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal. Electronic address: a.oehmen@fct.unl.pt.
authors.forename: A
authors.initials: A
authors.lastname: Oehmen
authors.affiliation: Instituto de Ingeniería del Agua y Medio Ambiente, Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain. Electronic address: rababa@dihma.upv.es.
authors.forename: R
authors.initials: R
authors.lastname: Barat
mesh_terms: D000332:Aerobiosis; D000693:Anaerobiosis; D001419:Bacteria / Q000378:metabolism*; D018533:Biomass; D019149:Bioreactors / Q000382:microbiology; D006003:Glycogen / Q000378:metabolism; D053858:Metabolic Networks and Pathways; D008954:Models, Biological; D011122:Polyphosphates / Q000378:metabolism*
chemical_list: D011122:Polyphosphates; D006003:Glycogen
keywords: Enhanced biological phosphorus removal (EBPR); Glycogen accumulating metabolism (GAM); Metabolic models; Polyphosphate (poly-P); Polyphosphate accumulating metabolism (PAM); Polyphosphate accumulating organism (PAO)