Distributed Sliding Mode Control of pH in Tubular Photobioreactors

Bioprocess strategies for enhancing biomolecules productivity in Chlorella fusca LEB 111 using CO2 a carbon source

“…There is a complex relation between the CO 2 concentration and the pH in microalgal culture, owing to the chemical equilibrium among the chemical species of carbon (CO 2 , H 2 CO 3 , HCO 3 − , and CO 3 −2 ) . Andrade et al showed that the inorganic carbon distribution inside a photobioreactor can show changes over a steady state pH range. When the pH values remained between 6.5 and 10.5, the bicarbonate fraction was the most abundant form.…”

“…Tang et al 13 ). 11,34 Andrade et al 34 showed that the inorganic carbon distribution inside a photobioreactor can show changes over a steady state pH range.…”

Sustainability and process control: A survey and perspective

“…Improvement of biomass productivity through tight pH and temperature control has been the main theme for optimal operation of microalgae-based processes. Control for the corresponding photobioreactors has been targeted using PI control [180], input/output linearizing control [181,182], nonlinear output feedback control [183], passivity-based control [184], sliding mode control [185], adaptive control [186], linear MPC [187][188][189][190][191] and nonlinear MPC [192,193]. Lack of continuous online measurements has motivated the use of interval state estimation [194], moving horizon estimation [189] and extended Kalman filtering [182].…”

“…Dynamic optimization has also been used to obtain lowcost operation profiles for outdoor open ponds while accounting for changing weather conditions [196]. Most of these control systems are verified on pilot-scale systems [180][181][182][183]185,187,188,192] and very few applications on an industrial-size system have been reported [190,191].…”

Fractional Sliding Mode Nonlinear Procedure for Robust Control of an Eutrophying Microalgae Photobioreactor

“…In practice, this is extremely difficult in photobioreactors due to the lack of reliable online measurements of metabolites and biomass concentrations [20]. On the other hand, Sliding Mode Control (SMC) is a well-known technique already successfully applied to photobioreactors [19,21]. However, this technique presents some theoretical and practical complications that hamper its application in industrial-scale bioreactors such as the monotonous switching feedback produced in the actuators, causing high-frequency flickering in the control action [21].…”