Performance Of Photobioreactor Research Articles

Effects of specific wavelengths of lights on performance of biofilm photobioreactor for treating septic tank effluent

Biofilm photobioreactors (BPBRs) employing algal-bacterial symbiotic reactions were designed as an on-site post-treatment system to treat septic tank effluent containing high concentrations of organic and nutrient matters. In this study, three BPBRs equipped with blue (peak wavelength ∼ 460 nm), red (peak wavelength ∼ 635) and mixed blue and red (50:50) lights for growing algal biomass (Chlorella sp.) were continuously operated at hydraulic retention times (HRT), light intensity and light/dark period of 6 days, 124 μmol/(m2.s) and 12/12 h, respectively. The experimental results illustrated that the chemical oxygen demand (COD) removal efficiency of 85 % and the highest total nitrogen (TN) and total phosphorus (TP) removal efficiencies of 87 and 84 %, respectively, were found in the BPBR with mixed blue and red lights, corresponding to the data of biomass productivity. Mass balance analyses of the BPBR performance indicated that TN (9.2 mg N/(L.d) or 74 %) and TP (0.73 mg P/(L.d) or 73 %) were mainly removed via biomass assimilation. Overall, the results of this study suggested that the mixed blue and red lights could enhance the biomass productivity and increase the treatment efficiencies of the BPBR system, resulting in the treated effluent meeting the discharge standards.

Waste to Sustainable Biohydrogen Production Via Photo-Fermentation and Biophotolysis − A Systematic Review

Considering the environmental challenges humanity faces in the 21st century, it is obvious that there is an enormous need for change of the global energy map. Under these circumstances, new energy sources and intermediates must be considered as options to limit the greenhouse gases emissions and mitigate climate crisis. Biohydrogen production is one of the most appealing options, due to hydrogen's multiple applications and zero emissions as a fuel, to empower a future hydrogen circular economy. In this review article we focus on two methods that are not widely used at industrial scale but have many future possibilities and growth margins: (a) photo-fermentation and (b) bio photolysis. Both methods are light dependent and need photobioreactors to function and produce significant amounts of biohydrogen. Based on an extensive literature search and systemic analysis of the findings, presentation of the different reactants, operating conditions and biohydrogen productions, key factors and effecting parameters were discussed. Temperature, pH, light intensity and photobioreactor operation and design are some of the most significant factors that define the biohydrogen production rates and yields. Innovative solutions and approaches are presented including biotechnological and genetic engineering modifications to microorganisms, as well as combinations of some hybrid biohydrogen producing methods, especially dark and photo fermentation. For implementing a biohydrogen circular-economy, different wastes were explored as potential feedstocks, and overcoming of major bottlenecks that biophotolysis and photo-fermentation face in the transition to a sustainable biohydrogen economy, were discussed.

Novel sequential flow baffled microalgal-bacterial photobioreactor for enhancing nitrogen assimilation into microalgal biomass whilst bioremediating nutrient-rich wastewater simultaneously

A novel sequential flow baffled microalgal-bacterial (SFB-AlgalBac) photobioreactor was designed to cater for the synergistic interactions between microalgal and bacterial consortia to enhance nitrogen assimilation into microalgal biomass from nutrient-rich wastewater medium. The performance of the SFB-AlgalBac photobioreactor was found to be optimum at the influent flow rate of 5.0 L/d, equivalent to 20 days of hydraulic retention time (HRT). The highest microalgal nitrogen assimilation rate (0.0271 /d) and biomass productivity (1350 mg/d) were recorded amidst this flow rate. Further increase to the 10.0 L/d flow rate reduced the photobioreactor performance, as evidenced by a reduction in microalgal biomass productivity (>10%). The microalgal biomass per unit of nitrogen assimilated values were attained at 16.69 mg/mg for the 5.0 L/d flow rate as opposed to 7.73 mg/mg for the 10.0 L/d flow rate, despite both having comparable specific growth rates. Also, the prior influent treatment by activated sludge was found to exude extracellular polymeric substances which significantly improved the microalgal biomass settleability up to 37%. The employment of SFB-AlgalBac photobioreactor is anticipated could exploit the low-cost nitrogen sources from nutrient-rich wastewaters via bioconversion into valuable microalgal biomass while fulfilling the requirements of sustainable wastewater treatment technologies.

Mapping the performance of photobioreactors for microalgae cultivation. Part II: equatorial and tropical climate zone

AbstractBACKGROUNDConsidering that the greatest proportion of microalgae commercial production is realized outdoors, it is critically important to highlight the role of the local climate in the performance of the processes. Currently, there is a tendency to identify locations with suitable climates for the large‐scale implementation of microalgae‐based processes. Therefore, this study proposed to map the performance of photobioreactors for microalgae culture. Fourteen types of climates distributed in 33 geographical locations representative of the equatorial and tropical zones of the world were evaluated. The simulated climatic elements were solar irradiation, temperature and photoperiod.RESULTSThe results showed that the tropical with dry winter (Aw), tropical with dry summer (As), tropical monsoon (Am), tropical fully humid (Af), hot steppe (BSh) and hot desert (BWh) climates favored the system productivities. The highest biomass productivity (0.347 g L–1 d–1) and lipid (0.048 g L–1 d–1) were registered in the Aw simulation.CONCLUSIONThe results of this study provide a useful database of the effects of climate for the microalgae photoautotrophic production. © 2020 Society of Chemical Industry

Production of β-carotene with Dunaliella salina CCAP19/18 at physically simulated outdoor conditions.

Batch growth and β‐carotene production of Dunaliella salina CCAP19/18 was investigated in flat‐plate gas‐lift photobioreactors with a light path of 2 cm, operated in physically simulated outdoor conditions. Dunaliella salina CCAP19/18 showed robust growth with respect to pH 8.0‐9.0 and 15–35°C at increasing salinity, simulating the evaporation of open photobioreactors. The highest β‐carotene concentration of 25 mg L‐1 (3 mg gCDW −1) was observed in batch processes at pH 8.5, 15–30°C and increasing salinity up to 110 g L‐1, simulating a typical Mediterranean summer climate. Intracellular β‐carotene accumulation of D. salina CCAP19/18 was shown to be independent of light availability, although nutrient limitation (K2HPO4, MgSO4, and/or ammonium ferric citrate) seems to enable stable β‐carotene content in the algal cells despite increasing cell densities in the photobioreactor. Fully controlled, lab‐scale photobioreactors simulating typical climate conditions of any region of interest are valuable tools for enabling a realistic characterization of microalgae on a laboratory scale, for production processes projected in open photobioreactor systems (e.g. thin‐layer cascade photobioreactors).

Split internal-loop photobioreactor for Scenedesmus sp. microalgae: Culturing and hydrodynamics

In this study, the evaluation of the performance of the split internal loop photobioreactor for culturing a species of green microalgae, Scenedesmus sp. under different operating superficial gas velocity and during a different time of growth ( i.e. , starting for the first day until end day of the culturing process) was addressed. The evaluation of the performance of the split internal loop photobioreactor was included assessing the density, pH, temperature, viscosity, surface tension, the optical density, cell population, dry biomass, and chlorophyll of the culture medium of the microalgae culturing. Additionally, the hydrodynamics of a Split Internal-Loop Photobioreactor with microalgae culturing was comprehensively quantified. Radioactive particle tracking (RPT) and gamma-ray computed tomography (CT) techniques were applied for the first time to quantify and address the influence of microalgae culture on the hydrodynamic parameters. The hydrodynamics parameters such as local liquid velocity field, shear stresses, turbulent kinetic energy, and local gas holdup profiles were measured at different superficial gas velocities as well as under different times of algae growth. The obtained results indicate that the flow distribution may significantly affect the performance of the photobioreactor, which may have substantial effects on the cultivation process. The obtained experimental data can serve as benchmark data for the evaluation and validation of computational fluid dynamics (CFD) codes and their closures. This, in turn, allows us to develop efficient reactors and consequently improving the productivity and selectivity of these photobioreactors.

Comparative evaluation of continuous piggery wastewater treatment in open and closed purple phototrophic bacteria-based photobioreactors

Purple phototrophic bacteria (PPB) represent an innovative approach for wastewater treatment with a high metabolic plasticity, able to grow under aerobic and anaerobic conditions. This study comparatively assessed the long-term performance (450 days of operation) of an open and closed PPB-based photobioreactor treating of piggery wastewater (PWW). The influence of wastewater dilution, illuminated area to volume ratio, biomass settling and recirculation, and infrared light intensity on wastewater treatment was evaluated at 7 days of hydraulic retention time. An increase in PWW dilution from 4 to 8 folds did not entail higher TOC removal efficiencies (REs) in the open photobioreactor (87% versus 89%), but a significant increase in the closed photobioreactor (from 73% to 80%). The increase in the illuminated area to volume ratio increased TN-REs up to 99% and 49% in the open and closed photobioreactor, respectively, with a concomitant increase in the temperature of both systems. However, temperature control did not mediate a significant enhancement in PWW treatment. Biomass settling and recirculation resulted in higher TN-REs (80%) and TOC-REs (90%) in the closed photobioreactor. The increase in infrared radiation from 100 to 300 W m-2 fostered PPB growth. High water evaporation losses (deteriorating effluent quality) were recorded in the open photobioreactor, where carbon dioxide and ammonia stripping were identified as the main pathways supporting carbon and nitrogen removal.

Optimization of photosynthetic biogas upgrading in closed photobioreactors combined with algal biomass production

Photosynthetic biogas upgrading in microalgae photobioreactors constitutes a sustainable and environmentally friendly technology for the simultaneous removal of CO2 and H2S from raw biogas. The potential of algal-bacterial symbiosis for biogas purification has been already studied and demonstrated in open photobioreactors. However, few studies have focused on the implementation of this process in closed photobioreactors, which offer higher photosynthetic efficiencies, enhanced biomass productivities, a limited N2 contamination and improved CO2 mass transfer. In this study, the influence of alkalinity (inorganic carbon concentrations from ∼200 to ∼1700 mg L–1), and nitrogen (N) deprivation strategies (24 or 48 h limitation) on both biomethane quality and biomass composition has been evaluated and optimized in a closed tubular photobioreactor (TPBR) interconnected to a mixing chamber and a biogas absorption column (total working volume of 132 L). The increase in the alkalinity of the cultivation broth mediated an increase in the upgrading performance of the TPBR, reaching CO2 removals of 96.3 ± 0.8 %, and a complete H2S abatement, resulting in an enhanced biomethane composition (CH4 = 97.2 ± 0.9 %). Moreover, process operation under N deprivation did not affect the quality of biomethane, which complied with standards required for injection into natural gas grids or use as vehicle fuel. N-deprivation promoted the continuous storage of intracellular carbohydrates (29.0 ± 4.4 % compared with 14.3 ± 2.1 % obtained under N excess). A maximum biomass productivity obtained was of 15.8 ± 4.3 g m–2 d–1 during N excess vs. 11.2 ± 3.3 g m–2 d–1 during N-deprivation at 26.8 d of hydraulic retention time. During the N feast-famine cycles, the cyanobacterial species Pseudanabaena sp. was dominant over green algae.

DNA metabarcoding reveals microbial community dynamics in a microalgae-based municipal wastewater treatment open photobioreactor

Controlling the growth of desired algal strains in microalgal-based wastewater treatment systems is challenging, and understanding the dynamics and interactions in the system is vital for proper management. A pilot-scale open photobioreactor located in Northern Sweden, was inoculated with the culture collection strain Scenedesmus dimorphus UTEX 417, which had been grown in Nordic climate for 8 years. The microbial diversity of eukaryotic and prokaryotic communities and their seasonal dynamics were revealed throughout the growth period by high-throughput sequencing of 18S and 16S rRNA genes and correlated with various environmental factors. S. dimorphus was stable in batch culture, but other microalgae appeared during semi-batch mode and co-dominated the system as a consequence of predation by zooplankton. Desmodesmus, Pseudocharaciopsis, Chlorella, Characium and Oocystis were the main microalgal species co-occurring in the system, with Characium and Chlorella acting as main competitors to Scenedesmus. Proteobacteria, Firmicutes, Bacteroidetes and Actinobacteria were the most abundant bacterial phyla, some of which showing significant positive or negative influence on Scenedesmus growth over time. Light, temperature, dissolved oxygen, pH and nutrients concentrations were found to have significant influence on the bacterial and/or zooplanktonic community changes.

Nitrification of anaerobic digestate using a consortium of microalgae and nitrifiers in an open photobioreactor with moving bed carriers

A consortium of microalgae and nitrifiers has attracted attention as an alternative to the expensive traditional nitrification process. A possible obstacle to achieving this is the inhibition of nitrifiers under strong light irradiation. This study evaluated the effect of moving bed carriers on anaerobic digestate nitrification in an open photobioreactor inoculated with microalgae and nitrifiers under an incident light intensity of 1000 μmol photons m−2 s−1. The results showed higher specific nitrification activity in the carrier-added photobioreactor (103.6 mg-N g-TSS day−1) than in one in which no carrier was added (11.7 mg-N g-TSS day−1). The empirical equations for determining the light intensity at different depths in the photobioreactor showed a significant contribution by carriers in attenuating the incident light intensity. This is due to the large light attenuation caused by the carrier (1.09 cm−1). The average light intensity inside of the photobioreactor decreased considerably in the carrier-added photobioreactor (342 μmol photons m−2 s−1), whereas it did not decrease in the one with no added carrier. It was found that specific nitrification activity was significantly negatively affected by average light intensity inside of the reactor, and not by incident light intensity, by combining the results from different studies including ours. This study demonstrated, for the first time, the effectiveness of adding moving bed carriers in photobioreactors to mitigate light inhibition of nitrifiers in a consortium of microalgae and nitrifiers.

Assessing the performance of membrane photobioreactors (MPBR) for polishing effluents containing different types of nitrogen

Membrane photobioreactors (MPBR) have the opportunity to remove various forms of nitrogen, such as ammonium and nitrate, found in high quantities in secondary effluent. This study provides a holistic comparison of the performance of two membrane photobioreactors treating secondary effluents containing ammonium (NH4+-N) or nitrate (NO3−-N) as the sole nitrogen source. Sophisticated analyses, such as flow cytometry, polymerase chain reaction denaturing gradient gel electrophoresis, liquid chromatography – organic carbon detection analysis and fluorescence excitation-emission matrix spectroscopy, were used to provide insight into system characteristics and performance. In terms of treatment efficiency, NH4+-N was better removed from the system (by 56%) compared to NO3−-N (33%). The MPBR fed with NH4+-N produced less microalgal cells (4.4 × 107 cells/ml compared to 5.3 × 107 cells/ml in that treating NO3−-N) but higher proportion of bacteria (6.3% compared to 2.1%), leading to a higher system heterogeneity. The biomass produced from the MPBR treating NH4+-N featured a higher level of extracellular materials and a lower dewaterability (as suggested by a significantly higher capillary suction time of 25.2 s than 13.1 s observed for the culture grown on NO3−-N), indicating a lower harvesting potential. As a result, faster membrane fouling was observed when NH4+-N was fed. This leads to a recommendation that operating conditions are optimised dependent on the form of nitrogen that needs to be treated.

Multiscale numerical workflow describing microalgae motion and light pattern incidence towards population growth in a photobioreactor

In this article, a numerical workflow describing the microalgal growth inside of a photobioreactor is proposed. CFD is used to compute reactor internal hydrodynamics taking into account marine impeller rotation and sparged bubbles motion. Lagrangian approach is used to track microalgae motion inside of the culture vessel. The illumination across the reactor is obtained using the classical Beer-Lambert’s law. The combination of light field and cell motion allows to reconstruct the light history of each microalgae. These histories are then supplied to Han’s model which predicts individual growth rate and experienced photodamages. Once computed, several thousands of trajectories are agglomerated at the population level yielding the photobioreactor performances. After having ensured properties convergence, this procedure is applied to a large range of optical density (0 to 4.0), i.e. cell concentration, and incident light intensities (0 to 2000 μmolPhoton/m2/s). From this exploration, it is possible to determine the photobioreactor response surfaces in terms of growth rate and photodamages. These are latter used to propose an optimal lighting strategy for biomass production - reducing photobioreactor operation time by 16% compared to classical two-step procedure - and assist light induced stress with the aim of triggering secondary metabolites production.

Mapping the performance of photobioreactors for microalgae cultivation: geographic position and local climate

AbstractBACKGROUNDOver 90% of microalgae cultivations on a commercial scale are grown in outdoor systems, which means that the performance of these bioprocesses is dependent on the climatic conditions in each particular locality. Thus, the selection of suitable locations according to their climatic conditions is extremely important to develop technically and economically viable processes. This study aimed to assess the influence of geographic position and local climate on the microalgae culture performance in photobioreactors, as a strategy to map potential regions for commercial‐scale microalgae production. Six extreme positions of Brazil were chosen to represent their respective climates in the four seasons of the year.RESULTSThe climatic variables considered were temperature, light irradiance, and photoperiod. In terms of both biomass and lipid production in an annual overview, the results showed that tropical climates and low latitudes favor the microalgae culture. The highest annual average biomass productivity (0.278 g L−1 d−1) and annual average lipid productivity (0.056 g L−1 d−1) were recorded in Boa Vista‐RR (02° 49′ 12″ N), in summer.CONCLUSIONThe geographic position and the local climate are decisive criteria in the performance of these processes, being able to increase up to three and four times the biomass productivity and lipid productivity, respectively. © 2020 Society of Chemical Industry

Limnospira indica PCC8005 growth in photobioreactor: model and simulation of the ISS and ground experiments

The Arthrospira-B experiment is the first experiment in space ever allowing the online measurements of both oxygen production rate and growth rate of Limnospira indica PCC8005 in batch photobioreactors running on-board ISS. Four bioreactors were integrated in the ISS Biolab facility. Each reactor was composed of two chambers (gas and liquid) separated by a PTFE membrane and was run in batch conditions. Oxygen production was monitored by online measurement of the total pressure increase in the gas chamber. The experiments are composed of several successive batch cultures for each reactor, performed in parallel on ISS and on ground. In this work, a model for the growth of the cyanobacterium Limnospira indica PCC8005 (also known as Arthrospira or spirulina) in these space membrane photobioreactors was proposed and the simulation results obtained are compared to the experimental results gathered in space and on ground.The photobioreactor model was based on a light transfer limitation model, already used to describe and predict the growth and oxygen production in small to large scale ground photobioreactors. It was completed by a model for pH prediction in the liquid phase allowing assessment of the pH increase associated to the bicarbonate consumption for the biomass growth. A membrane gas-liquid transfer model is used to predict the gas pressure increase in the gas chamber. Substrate limitation is considered in the biological model.A quite satisfactory fit was achieved between experimental and simulation results when a suitable mixing of the liquid phase was maintained. The data showed that microgravity has no first order effect on the oxygen production rate of Limnospira indica PCC8005 in a photobioreactor operating in space in zero gravity conditions.

Upgrading industrial effluent for agricultural reuse: effects of digestate concentration and wood vinegar dosage on biosynthesis of plant growth promotor.

Emphasis on water reuse in agricultural sector receives a renewed interest to close the loop in circular economy, especially in dry and water-stressed regions. In this work, wastewater from cooperative smoked sheet rubber factory and the effluent (digestate) from its treatment system (anaerobic digester) were used as medium to grow purple non-sulfur bacteria (PNSB), Rhodopseudomonas palustris strain PP803, with wood vinegar supplement at mid-log growth phase to stimulate the release of 5-aminolevulinic acid (ALA), a plant growth promotor. Wastewater-to-digestate ratios (D:W) represented by soluble chemical oxygen demand (SCOD) were found to influence both the growth of R. palustris and synthesis of ALA. The highest ALA release of 16.02 ± 0.75μM and the biomass accumulation of 1302 ± 78mg/L were obtained from the medium SCOD of 4953mg/L. Although retarding biomass accumulation by 28-36%, wood vinegar (WV) addition was proven to improve ALA release by 40%. Result suggested that SCOD of 3438mg/L (75:25 D:W) contained sufficient carbon source for PNSB growth and was chosen to subsequently run the photo-bioreactor (PBR) to sustain R. palustris PP803 cells production. In continuous PBR operation, PNSB proliferation suffered from the low organic concentration in PBR at low organic loading. An organic loading increase to 1.21gCOD/Lday was found to attain highest biomass concentration and longest PNSB dominant period over microalgea. In this study, a real-time monitoring protocol of PNSB and microalgae was specifically developed based on image color analysis at acceptable accuracy (R2 = 0.94). In the final assay, verification of the PBR-grown inoculant was conducted and ALA release efficiency was discussed under various wood vinegar dosages and dosing frequencies. This work has advanced our understandings closer to practical field application.

Biophotonics for improving algal photobioreactor performance: A review

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Municipal wastewater treatment by purple phototropic bacteria at low infrared irradiances using a photo-anaerobic membrane bioreactor

Light energy is one of the major costs for phototrophic systems. This study evaluated the photoreactor efficiency of purple phototropic bacteria anaerobic membrane bioreactor (PAnMBR) at low irradiance for the treatment of municipal wastewater. Infrared irradiance levels of 3.0 and 1.4 W/m2 produced by an infrared (IR) lamp emitting in the 800–900 nm wavelength range were investigated, with the ultimate goal of optimizing the irradiance energy demand. Experimental and modeling results demonstrated the ability of PPB to grow and treat raw municipal wastewater at the applied low irradiances, with effluent quality below target limits of TCOD˂50 mg/L, TN˂10 mg/L, and TP˂1 mg/L. While Monod kinetic parameters, km and Y, were determined to be lower than previous high-energy studies (1.9 mgCOD/mgVSS-d and 0.38 mgVSS/mgCOD, respectively), the photobioreactor performance were consistently maintained, indicating that energy cost associated with IR illumination can be reduced by up to 97%. To determine whether the treatment process could approach energy neutrality, subsequent anaerobic digestion experiments of the residual PPB biomass proved a potential for biogas recovery of up to 240 NmLCH4/gVSSadded, and a moderate biomass biodegradability of 41%. As a result, the net energy consumption of the process was estimated at 0.5 kWh/m3 of treated municipal wastewater, considering an energy demand for illumination of 0.67 kWh/m3 and an energy recovery attributed to the anaerobic digestion of 0.17 kWh/m3 from the excess PPB biomass wasted from PAnMBR.

Improving membrane photobioreactor performance by reducing light path: operating conditions and key performance indicators

Microalgae cultivation has been receiving increasing interest in wastewater remediation due to their ability to assimilate nutrients present in wastewater streams. In this respect, cultivating microalgae in membrane photobioreactors (MPBRs) allows decoupling the solid retention time (SRT) from the hydraulic retention time (HRT), which enables to increase the nutrient load to the photobioreactors (PBRs) while avoiding the wash out of the microalgae biomass.The reduction of the PBR light path from 25 to 10 cm increased the nitrogen and phosphorus recovery rates, microalgae biomass productivity and photosynthetic efficiency by 150, 103, 194 and 67%, respectively.The areal biomass productivity (aBP) also increased when the light path was reduced, reflecting the better use of light in the 10-cm MPBR plant. The capital and operating operational expenditures (CAPEX and OPEX) of the 10-cm MPBR plant were also reduced by 27 and 49%, respectively.Discharge limits were met when the 10-cm MPBR plant was operated at SRTs of 3–4.5 d and HRTs of 1.25–1.5 d. At these SRT/HRT ranges, the process could be operated without a high fouling propensity with gross permeate flux (J20) of 15 LMH and specific gas demand (SGDp) between 16 and 20 Nm3air·m−3permeate, which highlights the potential of membrane filtration in MPBRs.When the continuous operation of the MPBR plant was evaluated, an optical density of 680 nm (OD680) and soluble chemical oxygen demand (sCOD) were found to be good indicators of microalgae cell and algal organic matter (AOM) concentrations, while dissolved oxygen appeared to be directly related to MPBR performance. Nitrite and nitrate (NOx) concentration and the soluble chemical oxygen demand:volatile suspended solids ratio (sCOD:VSS) were used as indicators of nitrifying bacteria activity and the stress on the culture, respectively. These parameters were inversely related to nitrogen recovery rates and biomass productivity and could thus help to prevent possible culture deterioration.

A method to assess algicidal activity of microalgal extracts coupling microalgae produced in stirred closed photobioreactor operating in continuous with pulse amplitude modulated (PAM) fluorometry

We describe in the present study a quick and reliable method based on chlorophyll a fluorescence to assess putative algicidal effect of different microalgal extracts. We couple microalgal production under chemostat cultivation mode to continuously produce a given microalgae species (e.g. Dunaliella salina in this study) at a stable physiological state to ease comparison between extracts tested; with a non-destructive method based on chlorophyll a fluorescence. Pulse amplitude modulated (PAM) fluorometry was used to assess over time the effect of different microalgal crude extracts on the efficiency of the photosystem II (PSII) of a tested microalgae (Dunaliella salina).• Microalgal production at stationary phase in stirred closed photobioreactor (PBR) operating in continuous have stable photophysiological parameters, which is a prerequisite to compare the impact of different algicidal compounds.• The combination of both methods, allows to quickly assess the algicidal effect of diverse microalgal (crude) extracts on the PSII efficiency of a tested microalgae.• The method may be used to identify and isolate algicidal molecules affecting algal PSII using a bio-guided isolation protocol.

Quantitative Research of Photobioreactor Performance Based on an Improved Surface Fitting Method

The relationship between performance and working conditions in photobioreactor hydrogen production systems illuminated by a variable intensity light source has been described quantitatively using relational expressions. First, based on the finite volume method and the Michaelis-Menten model, the hydrogen production process of a photobioreactor (PBR) system was simulated numerically. Then, the performance of the PBR system was evaluated considering the hydrogen production rate, dimensionless hydrogen production rate, hydrogen production thrust coefficient and conversion efficiency of light energy to hydrogen energy rate as performance parameters, and the relationship between these parameters and working conditions was studied. Finally, the improved quantum-behaved particle swarm optimization (IQPSO) and surface fitting technique based on the curve fitting method were used to obtain relational expressions about the performance and working conditions of the PBR. All of the results show that the method can obtain accurately relational expressions for the performance optimization and forecasts of the PBR system.