title: Towards a consensus-based biokinetic model for green microalgae - The ASM-A.
abstract: Cultivation of microalgae in open ponds and closed photobioreactors (PBRs) using wastewater resources offers an opportunity for biochemical nutrient recovery. Effective reactor system design and process control of PBRs requires process models. Several models with different complexities have been developed to predict microalgal growth. However, none of these models can effectively describe all the relevant processes when microalgal growth is coupled with nutrient removal and recovery from wastewaters. Here, we present a mathematical model developed to simulate green microalgal growth (ASM-A) using the systematic approach of the activated sludge modelling (ASM) framework. The process model - identified based on a literature review and using new experimental data - accounts for factors influencing photoautotrophic and heterotrophic microalgal growth, nutrient uptake and storage (i.e. Droop model) and decay of microalgae. Model parameters were estimated using laboratory-scale batch and sequenced batch experiments using the novel Latin Hypercube Sampling based Simplex (LHSS) method. The model was evaluated using independent data obtained in a 24-L PBR operated in sequenced batch mode. Identifiability of the model was assessed. The model can effectively describe microalgal biomass growth, ammonia and phosphate concentrations as well as the phosphorus storage using a set of average parameter values estimated with the experimental data. A statistical analysis of simulation and measured data suggests that culture history and substrate availability can introduce significant variability on parameter values for predicting the reaction rates for bulk nitrate and the intracellularly stored nitrogen state-variables, thereby requiring scenario specific model calibration. ASM-A was identified using standard cultivation medium and it can provide a platform for extensions accounting for factors influencing algal growth and nutrient storage using wastewater resources.
authors.affiliation: Department of Environmental Engineering, Technical University of Denmark, Miljøvej, Building 113, 2800 Kgs. Lyngby, Denmark. Electronic address: dosaw@env.dtu.dk.
authors.forename: Dorottya S
authors.initials: DS
authors.lastname: Wágner
authors.affiliation: Department of Environmental Engineering, Technical University of Denmark, Miljøvej, Building 113, 2800 Kgs. Lyngby, Denmark. Electronic address: bvape@env.dtu.dk.
authors.forename: Borja
authors.initials: B
authors.lastname: Valverde-Pérez
authors.affiliation: Department of Environmental Engineering, Technical University of Denmark, Miljøvej, Building 113, 2800 Kgs. Lyngby, Denmark.
authors.forename: Mariann
authors.initials: M
authors.lastname: Sæbø
authors.affiliation: Department of Environmental Engineering, Technical University of Denmark, Miljøvej, Building 113, 2800 Kgs. Lyngby, Denmark.
authors.forename: Marta
authors.initials: M
authors.lastname: Bregua de la Sotilla
authors.affiliation: Department of Environmental Engineering, Technical University of Denmark, Miljøvej, Building 113, 2800 Kgs. Lyngby, Denmark.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Van Wagenen
authors.affiliation: Department of Environmental Engineering, Technical University of Denmark, Miljøvej, Building 113, 2800 Kgs. Lyngby, Denmark.
authors.forename: Barth F
authors.initials: BF
authors.lastname: Smets
authors.affiliation: Department of Environmental Engineering, Technical University of Denmark, Miljøvej, Building 113, 2800 Kgs. Lyngby, Denmark. Electronic address: beep@env.dtu.dk.
authors.forename: Benedek Gy
authors.initials: BG
authors.lastname: Plósz
mesh_terms: D018533:Biomass; D032921:Consensus; D058086:Microalgae; D058433:Photobioreactors; D012722:Sewage; D062065:Wastewater
chemical_list: D012722:Sewage; D062065:Wastewater
keywords: Green microalgal growth; Nutrient storage; Parameter identifiability; Process modelling; Uncertainty and global sensitivity analysis