Photobioreactors for microalgal cultures: A Lagrangian model coupling hydrodynamics and kinetics

Abstract

Closed photobioreactors have to be optimized in terms of light utilization and overall photosynthesis rate. A simple model coupling the hydrodynamics and the photosynthesis kinetics has been proposed to analyze the photosynthesis dynamics due to the continuous shuttle of microalgae between dark and lighted zones of the photobioreactor. Microalgal motion has been described according to a stochastic Lagrangian approach adopting the turbulence model suitable for the photobioreactor configuration (single vs. two-phase flows). Effects of light path, biomass concentration, turbulence level and irradiance have been reported in terms of overall photosynthesis rate. Different irradiation strategies (internal, lateral and rounding) and several photobioreactor configurations (flat, tubular, bubble column, airlift) have been investigated. Photobioreactor configurations and the operating conditions to maximize the photosynthesis rate have been pointed out. Results confirmed and explained the common experimental observation that high concentrated cultures are not photoinhibited at high irradiance level.

Turbidostat operation of outdoor pilot-scale photobioreactors

“…Increased pigmentation at higher biomass concentration was observed and will be discussed later. In addition, it was hypothesised by others that the effect of photo inhibition and light/dark fluctuations in microalgae cultures are tightly coupled, and that photo inhibition becomes more dominant in slowly mixed systems with relatively long exposure times to high light in the surface layers of the culture [33]. When comparing the different systems it is important to note that configuration and mixing are completely different [11,34,35].…”

Biogas purification via optimal microalgae growth: A literature review

“…In this framework, works like Ref. use this detailed PSU mechanism to obtain a dynamical model that gathers the photosynthesis kinetics with the hydrodynamics present in the photobioreactor. By considering that the motion of the microalgae is a Lagrangian random walk, they keep track of the trajectory in order to determine the instantaneous light intensity irradiated to the cell.…”

Multi-Physics Modeling of Light-Limited Microalgae Growth in Raceway Ponds

“…The coupling of photosynthesis kinetics, hydrodynamics, and light attenuation was first investigated some 40 years ago (Sheth et al, 1977), and many detailed models have been proposed since then for photobioreactors, using either an Eulerian or a Lagrangian description; see, e.g., Pruvost et al (2008); Marshall and Sala (2011);Olivieri et al (2015). Coupled models of outdoor raceway ponds were also developed during the early 1990s in the scope of the Aquatic Species Program (Sukenik et al, 1991).…”