Microalgal cultures for the remediation of wastewaters with different nitrogen to phosphorus ratios: Process modelling using artificial neural networks

• Type: Article in International Scientific Journal
• Date: 2023

Authors

Salgado, EM (Author) Other; Esteves, AF (Author) Other; Goncalves, AL (Author) Other; Pires, JCM (Author) FEUP

Journal

Title: Environmental Research

Vol. 231

ISSN: 0013-9351

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 0 Citations

Scopus - 0 Citations

Associated Projects

ALiCE - ALiCE - Laboratório Associado em Engenharia Química

LEPABE - Financiamento Plurianual 2020-2023 da Unidade de I&D LEPABE - Laboratório de Engenharia de Processos, Ambiente, Biotecnologia e Energia

PhotoBioValue - Efeito da luz na configuração de fotobiorreatores para o cultivo de microalgas: aumento da eficiência fotossintética e valorização da biomassa

Other information

Authenticus ID: P-00Y-BAC

DOI: 10.1016/j.envres.2023.116076

Abstract (EN): Microalgae have remarkable potential for wastewater bioremediation since they can efficiently uptake nitrogen and phosphorus in a sustainable and environmentally friendly treatment system. However, wastewater composition greatly depends on its source and has a significant seasonal variability. This study aimed to evaluate the impact of different N:P molar ratios on the growth of Chlorella vulgaris and nutrient removal from synthetic wastewater. Furthermore, artificial neural network (ANN) threshold models, optimised by genetic algorithms (GAs), were used to model biomass productivity (BP) and nitrogen/phosphorus removal rates (RRN/RRP). The impact of various inputs culture variables on these parameters was evaluated. Microalgal growth was not nutrient limited since the average biomass productivities and specific growth rates were similar between the experiments. Nutrient removal efficiencies/rates reached 92.0 +/- 0.6%/6.15 +/- 0.01 mgN L-1 d-1 for nitrogen and 98.2 +/- 0.2%/0.92 +/- 0.03 mgP L-1 d-1 for phosphorus. Low nitrogen concentration limited phosphorus uptake for low N:P ratios (e.g., 2 and 3, yielding 36 +/- 2 mgDW mgP-1 and 39 +/- 3 mgDW mgP-1, respectively), while low phosphorus concentration limited nitrogen uptake with high ratios (e.g., 66 and 67, yielding 9.0 +/- 0.4 mgDW mgN-1 and 8.8 +/- 0.3 mgDW mgN-1, respectively). ANN models showed a high fitting performance, with coefficients of determination of 0.951, 0.800, and 0.793 for BP, RRN, and RRP, respectively. In summary, this study demonstrated that microalgae could successfully grow and adapt to N:P molar ratios between 2 and 67, but the nutrient uptake was impacted by these variations, especially for the lowest and highest N:P molar ratios. Furthermore, GA-ANN models demonstrated to be relevant tools for microalgal growth modelling and control. Their high fitting performance in characterising this biological system can contribute to reducing the experi-mental effort for culture monitoring (human resources and consumables), thus decreasing the costs of microalgae production.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 13