Selection of photosynthesis and respiration models to assess the effect of environmental conditions on mixed microalgae consortia grown on wastewater

Rossi, S.; Casagli, Francesca; Mantovani, Marco; Mezzanotte, Valeria; Ficara, Elena

doi:10.1016/j.biortech.2020.122995

Cited by 44 publications

(22 citation statements)

References 34 publications

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“…This function includes three parameters: maximum specific growth rate (μmax), optimal light for growth (IOPT) and the initial slope of light response curve (α). The values chosen for IOPT and α are close to those reported in similar works (Martinez et al, 2018;Rossi et al, 2020), while μMAX was calibrated (see section 2.2).…”

Section: Lightsupporting

confidence: 57%

“…Regarding pH, calibrated thresholds are close to those proposed by . The calibrated pHMIN was also experimentally observed in activity tests performed on algae-bacteria samples from a similar pilot-scale HRABP treating the liquid fraction of digestate from a waste sludge full scale digester (Rossi et al, 2020). The cardinal values for AOB and NOB are slightly different from those previously suggested for conventional activated sludge plant, where the working pH range is typically around neutrality.…”

Section: Sensitivity Analysis and Parameter Estimationmentioning

confidence: 82%

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ALBA: A comprehensive growth model to optimize algae-bacteria wastewater treatment in raceway ponds

et al. 2021

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This paper proposes a new model describing the algae-bacteria ecosystem evolution in an outdoor raceway for wastewater treatment. The ALBA model is based on a mass balance of COD, C, N and P, but also H and O. It describes growth and interactions among algae, heterotrophic and nitrifying bacteria, while local climate drives light and temperature. Relevant chemical/physical processes are also included. The minimum-law was used as ground principle to describe the multi-limitation kinetics. The model was setup and calibrated with an original data set recorded on a 56 m 2 raceway located in the South of France, continuously treating synthetic wastewater. The main process variables were daily measured along 443 days of operations and dissolved O2 and pH were on-line recorded. A sub-dataset was used for calibration and the model was successfully validated, along the different seasons over a period of 414 days. The model proved to be effective in reproducing both the short term nycthemeral dynamics and the long-term seasonal ones. The analysis of different scenarios reveals the fate of nitrogen and the key role played by oxygen and CO2 in the interactions between the different players of the ecosystem. On average, the process turns out to be CO2 neutral, as compared to a standard activated sludge where approximately half of the influent carbon will end up in the atmosphere. The ALBA model revealed that a suboptimal regulation of the paddle wheel can bring to several detrimental impacts. At high velocity, the strong aeration will reduce the available oxygen provided by photo-oxygenation, while without aeration, it can rapidly lead to oxygen inhibition of the photosynthetic process. On the other hand, during night, the paddle wheel is fundamental to ensure enough oxygen in the system to support algal-bacteria metabolism. The model can be used to support advanced control strategies, including smart regulation of the paddle wheel velocity to more efficiently balance the mixing, aeration and degassing effects.

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Section: Lightsupporting

confidence: 57%

Section: Sensitivity Analysis and Parameter Estimationmentioning

confidence: 82%

ALBA: A comprehensive growth model to optimize algae-bacteria wastewater treatment in raceway ponds

et al. 2021

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“…The cardinal model is a simple equation which considers a maximum, a minimum and an optimal value, the values of the variable (for instance, temperature) only existing on the range between maximum and minimum tolerable values (Ippoliti et al, 2016). Currently, cardinal equations are well accepted in the microalgae–bacteria models because they are helpful to represent experimental data and make the models straightforward to understand (Rossi et al, 2020).

R O_{2} (T) = \frac{(T - T italicmax) {(T - T \min)}^{2}}{\begin{matrix} trueleft \\ (Topt - T \min) (((Topt - T \min) (T - Topt)) \\ - ((Topt - T \max) (Topt + T \min - 2 T))) \end{matrix}}

…”

Section: Resultsmentioning

confidence: 99%

Modeling of photosynthesis and respiration rate for microalgae–bacteria consortia

Zurano

Gómez-Serrano

Acién-Fernández

et al. 2020

Biotech & Bioengineering

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In this article, the influence of culture conditions (irradiance, temperature, pH, and dissolved oxygen) on the photosynthesis and the respiration rates of microalgae–bacteria consortia in wastewater treatment was analyzed. Specifically, some short photo‐respirometric experiments, simulating outdoor raceway reactors, were performed to evaluate the response of microalgae, heterotrophic bacteria, and nitrifying bacteria to variations in environmental parameters. Results demonstrate that irradiance is the most dominant variable to determine microalgae photosynthesis rates. However, reduction in microalgae activity was not observed at higher irradiance, ruling out the existence of photoinhibition phenomena. Related to heterotrophic and nitrifying bacteria, their activities were strongly affected by the influence of temperature and pH. Moreover, the effect of dissolved oxygen concentrations on microalgae, and bacteria activities was studied, displaying a reduced photosynthetic rate at dissolved oxygen concentrations above 20 mg/L. Data have been used to develop an integrated model for each population (microalgae, heterotrophic bacteria, and nitrifying bacteria) based on considering the simultaneous influence of irradiance, temperature, pH, and dissolved oxygen. The models fit the experimental results in the range of culture conditions tested, and they were validated using data obtained by the simultaneous modifications of the variables. These individual models serve as a basis for developing a global biologic microalgae–bacteria model for wastewater treatment to improve the optimal design and management of microalgae‐based processes, especially outdoors, where the cultures are subject to variable daily culture conditions.

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“…For the acid-base interaction, the microalgal species determines whether it is suitable to grow in acidic, neutral, or alkaline conditions to attain optimum growth, which is a dominant mechanism for microalgal attachment. The variation in the normalized net photosynthesis rate with pH can be fitted to the cardinal model development for microalgae, which will determine the microalgae growth with the optimum pH [93,94]. The cardinal model is defined as a simple function such as net photosynthesis depending on a maximum, a minimum, and optimum value, with different values of the variables such as pH and temperature that only can be found in between the maximum and minimum tolerable values [94,95].…”

Section: Attached Microalgal Cultivationmentioning

confidence: 99%

“…The variation in the normalized net photosynthesis rate with pH can be fitted to the cardinal model development for microalgae, which will determine the microalgae growth with the optimum pH [93,94]. The cardinal model is defined as a simple function such as net photosynthesis depending on a maximum, a minimum, and optimum value, with different values of the variables such as pH and temperature that only can be found in between the maximum and minimum tolerable values [94,95]. Interestingly, Ippoliti et al [95] projected in their studies that temperature and pH demonstrated similar behavior when the net photosynthesis rate is zero under 12 • C and pH is 3, rising to a maximum value with 36 • C and pH 7.5, but decreasing to zero when it reached maximal values of 45 • C and pH 10.…”

Section: Attached Microalgal Cultivationmentioning

confidence: 99%

Assuaging Microalgal Harvesting Woes via Attached Growth: A Critical Review to Produce Sustainable Microalgal Feedstock

et al. 2021

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Third-generation biofuels that are derived from microalgal biomass have gained momentum as a way forward in the sustainable production of biodiesel. Such efforts are propelled by the intention to reduce our dependence on fossil fuels as the primary source of energy. Accordingly, growing microalgal biomass in the form of suspended cultivation has been a conventional technique for the past few decades. To overcome the inevitable harvesting shortcomings arising from the excessive energy and time needed to separate the planktonic microalgal cells from water medium, researchers have started to explore attached microalgal cultivation systems. This cultivation mode permits the ease of harvesting mature microalgal biomass, circumventing the need to employ complex harvesting techniques to single out the cells, and is economically attractive. However, the main bottleneck associated with attached microalgal growth is low biomass production due to the difficulties the microalgal cells have in forming attachment and populating thereafter. In this regard, the current review encompasses the novel techniques adopted to promote attached microalgal growth. The physicochemical effects such as the pH of the culture medium, hydrophobicity, as well as the substratum surface properties and abiotic factors that can determine the fate of exponential growth of attached microalgal cells, are critically reviewed. This review aims to unveil the benefits of an attached microalgal cultivation system as a promising harvesting technique to produce sustainable biodiesel for lasting applications.

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Selection of photosynthesis and respiration models to assess the effect of environmental conditions on mixed microalgae consortia grown on wastewater

Cited by 44 publications

References 34 publications

ALBA: A comprehensive growth model to optimize algae-bacteria wastewater treatment in raceway ponds

ALBA: A comprehensive growth model to optimize algae-bacteria wastewater treatment in raceway ponds

Modeling of photosynthesis and respiration rate for microalgae–bacteria consortia

Assuaging Microalgal Harvesting Woes via Attached Growth: A Critical Review to Produce Sustainable Microalgal Feedstock

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