Sensor-Based Turbidostat Operation Enables Biomass Setpoint Regulation and Productivity Improvement in semi-industrial Microalgae Raceway Pond

Fuente: arXiv
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Hauptverfasser: González-Hernández, José, Bernacchioni, Laura, Morillas-España, Ainoa, Guzmán, José Luis, Acién, Francisco Gabriel
Format: Preprint
Veröffentlicht: 2026
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author González-Hernández, José
Bernacchioni, Laura
Morillas-España, Ainoa
Guzmán, José Luis
Acién, Francisco Gabriel
author_facet González-Hernández, José
Bernacchioni, Laura
Morillas-España, Ainoa
Guzmán, José Luis
Acién, Francisco Gabriel
contents This work presents the experimental validation of a turbidostat strategy for biomass control in a semi-industrial outdoor raceway reactor. The proposed approach regulates biomass concentration by automatically triggering dilution when the online biomass estimate exceeds a predefined threshold. To ensure safe outdoor operation, dilution was restricted to daylight periods, avoiding biomass removal under low-radiation conditions. The strategy was implemented through an industrial control architecture using an optical monitoring system for online biomass estimation. Experiments were conducted over 14 consecutive days in an 80 m$^2$ (12000 L) raceway reactor. A second parallel reactor operated in chemostat mode, with a nominal dilution of 20 % of the total volume during operating days, provided contextual information under the same outdoor conditions. The analysis focuses on the ability of the sensor-based strategy to configure and maintain the desired biomass concentration, rather than on a direct reactor-to-reactor performance ranking. During the campaign, the biomass threshold in the turbidostat reactor was changed from 1.0 to 0.8 g L$^{-1}$, demonstrating the flexibility enabled by online biomass monitoring. Excluding initial adjustment and transition days, harvested areal productivity increased from 9.52 to 23.20 g m$^{-2}$ d$^{-1}$ after reducing the operating threshold. The overall biomass balance also showed higher net areal productivity in the turbidostat reactor, reaching 20.34 g m$^{-2}$ d$^{-1}$ compared with 11.16 g m$^{-2}$ d$^{-1}$ in the parallel chemostat reactor. These results demonstrate the feasibility of robust turbidostat-based biomass control in large-scale outdoor raceway photobioreactors.
format Preprint
id arxiv_https___arxiv_org_abs_2605_25113
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Sensor-Based Turbidostat Operation Enables Biomass Setpoint Regulation and Productivity Improvement in semi-industrial Microalgae Raceway Pond
González-Hernández, José
Bernacchioni, Laura
Morillas-España, Ainoa
Guzmán, José Luis
Acién, Francisco Gabriel
Systems and Control
This work presents the experimental validation of a turbidostat strategy for biomass control in a semi-industrial outdoor raceway reactor. The proposed approach regulates biomass concentration by automatically triggering dilution when the online biomass estimate exceeds a predefined threshold. To ensure safe outdoor operation, dilution was restricted to daylight periods, avoiding biomass removal under low-radiation conditions. The strategy was implemented through an industrial control architecture using an optical monitoring system for online biomass estimation. Experiments were conducted over 14 consecutive days in an 80 m$^2$ (12000 L) raceway reactor. A second parallel reactor operated in chemostat mode, with a nominal dilution of 20 % of the total volume during operating days, provided contextual information under the same outdoor conditions. The analysis focuses on the ability of the sensor-based strategy to configure and maintain the desired biomass concentration, rather than on a direct reactor-to-reactor performance ranking. During the campaign, the biomass threshold in the turbidostat reactor was changed from 1.0 to 0.8 g L$^{-1}$, demonstrating the flexibility enabled by online biomass monitoring. Excluding initial adjustment and transition days, harvested areal productivity increased from 9.52 to 23.20 g m$^{-2}$ d$^{-1}$ after reducing the operating threshold. The overall biomass balance also showed higher net areal productivity in the turbidostat reactor, reaching 20.34 g m$^{-2}$ d$^{-1}$ compared with 11.16 g m$^{-2}$ d$^{-1}$ in the parallel chemostat reactor. These results demonstrate the feasibility of robust turbidostat-based biomass control in large-scale outdoor raceway photobioreactors.
title Sensor-Based Turbidostat Operation Enables Biomass Setpoint Regulation and Productivity Improvement in semi-industrial Microalgae Raceway Pond
topic Systems and Control
url https://arxiv.org/abs/2605.25113