Algal Biomass Production Research Articles

Enhanced carotenoid production, biodiesel quality, and harvesting efficiency in microalga Graesiella emersonii via heterotrophic cultivation strategy

The aim of this study was to evaluate the potential industrial applicability of the green microalga Graesiella emersonii GEGS21 by comparing its biomass, photosynthetic pigments, and biodiesel properties under photoautotrophic (PA) and heterotrophic (HT) cultivation. Four agricultural soluble fertilizers (SFs) were tested as substitute medium for algal growth. Of these, three were not only cost-effective but also more efficient in promoting growth compared to the BG-11 algal medium. Supplementing the SF medium with 12 g/L of glucose significantly improved algal biomass productivity under HT condition, and the optimal conditions were identified as 0 M NaCl, a temperature of 30 °C, and a pH of 8. Subsequent supplementation with yeast extract led to a notable enhancement in algal growth, resulting in approximately 18.6-times higher biomass productivity compared to the PA condition. Under HT cultivation, the productivities of the photosynthetic pigments including lutein and zeaxanthin were significantly increased approximately by 3.6-fold and 3.5-fold, respectively compared to the PA condition (p < 0.05). Moreover, HT cultivation led to improved biodiesel properties, such as iodine value, cetane number, oxidative stability, and kinematic viscosity. These enhancements, achieved through altered fatty acid methyl ester composition, align with the ASTM D6751 and EN14214 biodiesel standards. Interestingly, when cultivated under HT conditions, algal strain exhibited higher sedimentation efficiency, accompanied by an enhanced cellular starch content, compared to both PA and mixotrophic conditions. This suggests a promising strategy for economically viable harvesting by altering the specific gravity of algal cells. In conclusion, our findings suggest that HT cultivation of Graesiella emersonii GEGS21 may serve as an effective approach to produce value-added compounds and bioenergy, offering potential for economical harvesting.

A Response Surface Methodology Study for Chlorella vulgaris Mixotrophic Culture Optimization.

Glycerol is a carbon source that produces good biomass under mixotrophic conditions. Enhancing the composition of culture media in algae biomass production improves growth rates, biomass yield, nutrient utilization efficiency, and overall cost-effectiveness. Among the key nutrients in the medium, nitrogen plays a pivotal role. Urea can be effectively used as a nitrogen source and is considered a low-cost form of nitrogen compared to other sources. Urea metabolism releases some CO2 in photosynthesis, and magnesium plays a major role in urea uptake. Magnesium is another key nutrient that is key in photosynthesis and other metabolic reactions. To maximize glycerol consumption in the mixotrophic system and to obtain high biomass and lipid productions, the variations in MgSO4·7H2O and urea concentrations were evaluated in the growth medium of the microalgae. A response surface methodology (RSM) using a central composite design (CCD) was designed to maximize glycerol consumption at the initial cellular growth rates (up to four days). The magnesium and urea supply varied from 0.3 to 1.7 g L-1. Response surface methodology was utilized to analyze the results, and the highest glycerol consumption rate, 770.2 mg L-1 d-1, was observed when C. vulgaris was grown at 1.7 g L-1 urea, 1.0 g L-1 MgSO4·7H2O. Using the optimal urea and magnesium concentrations with acetate, glucose, and glycerol as carbon sources, the same lipid content (10% average) was achieved on day 4 of mixotrophic C. vulgaris culture. Overall, the results show that mixotrophic growth of C. vulgaris using urea with an optimum magnesium concentration yields large amounts of fatty acids and that the carbon source greatly influences the profile of the fatty acids.

A Comprehensive Review of Microalgae and Cyanobacteria-Based Biostimulants for Agriculture Uses.

Significant progress has been achieved in the use of biostimulants in sustainable agricultural practices. These new products can improve plant growth, nutrient uptake, crop yield and quality, stress adaptation and soil fertility, while reducing agriculture's environmental footprint. Although it is an emerging market, the biostimulant sector is very promising, hence the increasing attention of the scientific community and agro-industry stakeholders in finding new sources of plant biostimulants. Recently, pro- and eucaryotic microalgae have gained prominence and can be exploited as biostimulants due to their ability to produce high-value-added metabolites. Several works revealed the potential of microalgae- and cyanobacteria-based biostimulants (MCBs) as plant growth promoters and stress alleviators, as well as encouraging results pointing out that their use can address current and future agricultural challenges. In contrast to macroalgae biostimulants, the targeted applications of MBs in agriculture are still in their earlier stages and their commercial implementation is constrained by the lack of research and cost of production. The purpose of this paper is to provide a comprehensive overview on the use of this promising new category of plant biostimulants in agriculture and to highlight the current knowledge on their application prospects. Based on the prevailing state of the art, we aimed to roadmap MCB formulations from microalgae and cyanobacteria strain selection, algal biomass production, extraction techniques and application type to product commercialization and farmer and consumer acceptance. Moreover, we provide examples of successful trials demonstrating the beneficial applications of microalgal biostimulants as well as point out bottlenecks and constraints regarding their successful commercialization and input in sustainable agricultural practices.

Data-driven recurrent neural networks modeling of cyanobacteria growth in bubble columns reactors under sparging with CO2-enriched Air

Cultivating carbohydrate-enriched microalgae in photobioreactors is a recognized method for converting atmospheric carbon dioxide (CO2) into valuable resources, offering a solution to combat industrial CO2 emissions. Achieving global carbon neutrality by 2050 necessitates an annual reduction of approximately 1.4 gigatons of CO2. To address this challenge, we developed a machine learning-based black box model using data from the Institute of Advanced Materials for Sustainable Manufacturing at ITESM. This dataset encompasses hourly operational parameters collected over eleven months, including temperature, pressure, and flow rate. These parameters were essential for a microalgal cultivation experiment using the cyanobacterium Desertifilum tharense and CO2-enriched air. Two 100-L photobioreactor systems were employed. Leveraging the sequential dataset, we deployed a long short-term memory network (LSTM) to predict CO2 percentages at reactor outlets, indirectly indicating algae biomass production. Seven input variables were selected on the basis of their impact on system behavior. Using advanced machine learning time series mathematical models can boost process intensification tasks through advanced process optimization, simulation, and control goals.

Defense responses of the green microalgae Chlorella vulgaris to the vanadium pentoxide nanoparticles

Although vanadium-based nanomaterials have found extensive use in industry, their influence on ecosystems and living organisms is not yet well investigated. In this study, hydrothermal methods were utilized for the synthesis of vanadium pentoxide nanoparticles (V2 O5 NPs). The gained NPs were characterized using XRD, FT-IR, EDS, DLS, SEM and TEM techniques. Subsequently, the toxic effects of V2 O5 NPs on the model green microalgae Chlorella vulgaris were evaluated. According to the obtained results, V2 O5 NPs caused a significant reduction in cell number and biomass production of algae in a dose and time dependent manner. Moreover, flow cytometric analysis confirmed a reduction in the quantity of living cells. Scanning electron microscopy showed plasmolysis and deformation of the cells after exposure to nanoparticles. The photosynthetic pigments and phenolics content exhibited a decrease in comparison with the control sample. Although, non-enzymatic antioxidant system in C. vulgaris displayed an average action, antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) showed a dose dependent increasing trend. These intercellular reactions designated the activation of the antioxidant defense system in response to the induced oxidative stress by V2 O5 NPs.

Enhancement of β-glucan production in two Arthrospira species cultivating in anaerobic digestion effluent of water hyacinth

Arthrospira is an edible cyanobacterium that contains valuable biomolecules, including proteins, carbohydrates, pigments, and β-glucans. This study aimed to determine the biochemical compositions of the two species of Arthrospira cultivated in anaerobic digestion effluent obtained from water hyacinth. This fast-growing aquatic macrophyte causes significant environmental issues worldwide. It’s an urgent issue to confirm the utility of such nuisance macrophyte for sustainable management of freshwater ecosystems. Even with six- and eight-fold diluted effluent containing a limited amount of phosphate, algal biomass production was 0.62 g/L, with higher carbohydrate but lower protein and lipid content than those in the algal cells cultivated with standard media. β-glucan was produced at 4–18% of algal dry mass, being 1.5–7 times higher than those in the standard media. Additionally, phosphate and ammonium removal efficiencies in the cultivation were over 96%. These findings suggest that cultivating Arthrospira using the effluent has promising potential for producing algal material including valuable biomolecules like β-glucans from nuisance macrophytes through sustainable nutrient recycling.

SẢN XUẤT SINH KHỐI TẢO Nannochloropsis oculata QUY MÔ HÀNG HÓA TẠI HUYỆN QUỲNH LƯU, NGHỆ AN

The research was conducted to complete technological protocol of biomass production of algae Nannochloropsis oculata with both culture methods in plastic bags and photo-bioreactor systems. The results show that in the nylon bag system, algae reached a peak of biomass density at day-8 of culture with 80 million cells per ml. In the photo-bioreactor systems, algae were higher density (180 million cells per ml), and longer period of culture (15 days of culture) than in plastic bags. The total products of 404.4 kg of fresh concetrated algae and 57.6 kg of dried algae powder which were suitable produced under climate conditions in Nghe An. All the algae products met the quality and requirements for use as food for aquatic animals as well as raw materials for the production of functional foods for humans.

Microalgae Production on Biogas Digestate in Sub-Alpine Region of Europe—Development of Simple Management Decision Support Tool

In a one-and-a-half-year study conducted in the ALS6 region in Europe (Ljubljana, Slovenia), the cultivation of microalgae in anaerobic digestate from food waste, mainly Scenedesmus dimorphus and Scenedesmus quadricauda, was investigated in three ponds (1260 L each) under a greenhouse. The effects of changing digestate quality and quantity as well as seasonal fluctuations on the productivity of the microalgae were investigated in three stages: Learning/Design (SI), Testing (SII), and Verification/Calibration (SIII). A decision support tool (DST) was developed using easy-to-measure parameters such as pH, temperature, electrical conductivity, mineral nitrogen forms and physical, biological parameters (OD, delayed fluorescence intensity). To control optimal pond operation, we proposed the photosynthetic culture index (PCI) as an early indicator for necessary interventions. Flocculation and nitrite levels (above 3 mg NO2-N L−1) were signals for the immediate remediation of the algae culture. Under optimal conditions in summer SIII, an average algal biomass production of 11 ± 1.5 g m−2 day−1 and a nitrogen use efficiency of 28 ± 2.6 g biomass/g N-input were achieved with the developed DST. The developed DST tool was, in this study, successfully implemented and used for the cultivation of microalgae consortia predominated by Scenedesmus dimorphus and S. quadricauda with biogas digestate. DST offers the possibility to be modified according to producers’ specific needs, facility, digestate and climate conditions, and as such, could be used for different microalgae cultivation processes with biogas digestate as a food source.

Effect of plant growth-promoting molecules on improving biomass productivity in DISCOVR production strains

Phytohormones (Growth-Promoting Molecules, GPMs) have specific functions in the life cycle of a plant and are known to regulate plant growth, development, and stress responses independently, as well as through crosstalk with each other. These phytohormones are actively used in agriculture at scale, due to their efficiency at very low concentrations, and they also can be cost effective. Two phytohormones, auxin (indole-3-acetic acid, IAA) and gibberellic acid (GA), have also been shown to improve cell division, growth, and biomass production in algae. To test if phytohormones might have a similar beneficial result on potential algae biomass production strains, we evaluated the effect of IAA and GA3 on top-performing algae DISCOVR strains, Chlorella sorokiniana 1412, Monoraphidium minutum 26B-AM, Picochlorum celeri TG2-WT-CSM/EMRE, and Tetraselmis striata LANL1001 under laboratory conditions. Both GPMs showed growth promoting effects, but in contrast to previously published studies, we did not observe any increase in lipid accumulation with either IAA or GA3 supplementation. Then, to test phytohormone effects in a simulated outdoor environment, IAA treatments were conducted in environmental photobioreactors, revealing that IAA treatment significantly increased the growth and total biomass of M. minutum 26B-AM. In addition, investigation of the M. minutum 26B-AM genome combined with transcriptome data analysis revealed the presence of genes putatively involved in auxin biosynthesis and signaling, demonstrating that IAA pathways found in other algal species are also present in M. minutum 26B-AM. Finally, to begin to gauge whether GPM treatment is a viable approach for increasing biomass productivity in outdoor cultivation, we assessed, for the first time, the effects of adding GPMs to algae during scaled cultivation and the associated implications on economics for modeled large-scale algae farms.

Efficient utilization of monosaccharides from agri-food byproducts supports Chlorella vulgaris biomass production under mixotrophic conditions

Microalgae are promising resources for the sustainable production of biofuels, feed, and high-value chemicals. Several strains can grow heterotrophically or mixotrophically on multiple organic substrates even if the high cost associated to their use can hinder scalability and economical sustainability of the overall process. The use of agri-food waste biomass hydrolysates might make the cultivation procedure more sustainable, while at the same time valorising underutilized by-products. In this study, Chlorella vulgaris biomass production and sugar utilization was investigated during mixotrophic cultivation on hydrolysates of two inexpensive and widely available recalcitrant agri-food waste biomasses: barley straw (BS) and citrus processing waste (CPW). CPW hydrolysate supported enhanced biomass production, compared to BS digestate, likely because of the presence, besides glucose, of significant amounts of galactose, which is rapidly metabolized by the algae. Notably, when pure monosaccharides were provided as sole organic carbon, growth stopped before complete sugar consumption. Arrested growth in presence of pure monosaccharides correlated with a drastic drop in extracellular pH, which appears to depend on both carbon and nitrogen sources. Our results show that mixotrophic cultivation of C. vulgaris on BS or CPW hydrolysates results in more efficient conversion of organic carbon into biomass, compared to growth on pure sugars, indicating that these agri-food by-products can be utilized as valid feedstocks for sustainable algal biomass production.

Application of Nanomaterials in the Production of Biomolecules in Microalgae: A Review.

Nanomaterials (NMs) are becoming more commonly used in microalgal biotechnology to empower the production of algal biomass and valuable metabolites, such as lipids, proteins, and exopolysaccharides. It provides an effective and promising supplement to the existing algal biotechnology. In this review, the potential for NMs to enhance microalgal growth by improving photosynthetic utilization efficiency and removing reactive oxygen species is first summarized. Then, their positive roles in accumulation, bioactivity modification, and extraction of valuable microalgal metabolites are presented. After the application of NMs in microalgae cultivation, the extracted metabolites, particularly exopolysaccharides, contain trace amounts of NM residues, and thus, the impact of these residues on the functional properties of the metabolites is also evaluated. Finally, the methods for removing NM residues from the extracted metabolites are summarized. This review provides insights into the application of nanotechnology for sustainable production of valuable metabolites in microalgae and will contribute useful information for ongoing and future practice.

Energy balance survey for the design and auto-thermal thermophilic aerobic digestion of algal-based membrane bioreactor for Landfill Leachate Treatment(under organic loading rates): Experimental and simulation-based ANN and NSGA-II

Although algal-based membrane bioreactors (AMBRs) have been demonstrated to be effective in treating wastewater (landfill leachate), there needs to be more research into the effectiveness of these systems. This study aims to determine whether AMBR is effective in treating landfill leachate with hydraulic retention times (HRTs) of 8, 12, 14, 16, 21, and 24 h to maximize AMBR's energy efficiency, microalgal biomass production, and removal efficiency using artificial neural network (ANN) models. Experimental results and simulations indicate that biomass production in bioreactors depends heavily on HRT. A decrease in HRT increases algal (Chlorella vulgaris) biomass productivity. Results also showed that 80% of chemical oxygen demand (COD) was removed from algal biomass by bioreactors. To determine the most efficient way to process the features as mentioned above, nondominated sorting genetic algorithm II (NSGA-II) techniques were applied. A mesophilic, suspended-thermophilic, and attached-thermophilic organic loading rate (OLR) of 1.28, 1.06, and 2 kg/m3/day was obtained for each method. Compared to suspended-thermophilic growth (3.43 kg/m3.day) and mesophilic growth (1.28 kg/m3.day), attached-thermophilic growth has a critical loading rate of 10.5 kg/m3.day. An energy audit and an assessment of the system's auto-thermality were performed at the end of the calculation using the Monod equation for biomass production rate (Y) and bacteria death constant (Kd). According to the results, a high removal level of COD (at least 4000 mg COD/liter) leads to auto-thermality.

The utility of algae as sources of high value nutritional ingredients, particularly for alternative/complementary proteins to improve human health.

As the global population continues to grow, the demand for dietary protein is rapidly increasing, necessitating the exploration of sustainable and nutritious protein sources. Algae has emerged as a promising food source due to their high value ingredients such as proteins, as well as for their environmental sustainability and abundance. However, knowledge gaps surrounding dietary recommendations and food applications restrict algae's utilization as a viable protein source. This review aims to address these gaps by assessing the suitability of both microalgae and macroalgae as alternative/complementary protein sources and exploring their potential applications in food products. The first section examines the potential suitability of algae as a major food source by analyzing the composition and bioavailability of key components in algal biomass, including proteins, lipids, dietary fiber, and micronutrients. Secondly, the biological effects of algae, particularly their impact on metabolic health are investigated with an emphasis on available clinical evidence. While evidence reveals protective effects of algae on glucose and lipid homeostasis as well as anti-inflammatory properties, further research is required to understand the longer-term impact of consuming algal protein, protein isolates, and concentrates on metabolic health, including protein metabolism. The review then explores the potential of algal proteins in food applications, including ways to overcome their sensory limitations, such as their dark pigmentation, taste, and odor, in order to improve consumer acceptance. To maximize algae's potential as a valuable protein source in the food sector, future research should prioritize the production of more acceptable algal biomass and explore new advances in food sciences and technology for improved consumer acceptance. Overall, this paper supports the potential utility of algae as a sustainable and healthy ingredient source for widespread use in future food production.

Carbon capture from petrol-engine flue gas: Reviving algae-based sequestration with integrated microbial fuel cells

Strengthening the existing CO2 capture technologies is crucial for averting the imminent climate crisis. The present study undertakes the algae-assisted microbial fuel cell (MFC) for indirect CO2 capture via bicarbonate utilization through natural photosynthesis process. The flue gas is first cooled using a heat exchanger and then directed to a sieve-plate absorption column where sodium carbonate supplemented wastewater absorbs CO2 generating flue gas-derived bicarbonates (FGDBs). The FGDBs are added in the plastic bag photobioreactors (PBRs) coupled with the MFC for absorption by Chlorella vulgaris. Adding FGDB at the MFC cathode increased the algae biomass productivity two times (0.677 ± 0.086 Kg/m3/d) compared to the cathode without FGDB. The algae could efficiently utilize 76.84 ± 1.23 %. More than 50 % of sodium carbonate can be recycled for the next round of CO2 capture. FGDB supplementation at the cathode improved MFC’s electrical energy production (0.0066 kWh/m3) by 1.5 times through enhanced anodic and cathodic currents. Therefore, the present study offers a biochemical CO2 sequestration process that generates power, algae biomass, and treats water by utilizing algae-assisted MFC for flue gas carbon capture.

A photobioreactor for production of algae biomass from gaseous emissions of an animal house

Sustainable approaches to circular economy in animal agriculture are still poorly developed. Here, we report an approach to reduce gaseous emissions of CO2 and NH3 from animal housing while simultaneously using them to produce value-added biomass. To this end, a cone-shaped, helical photobioreactor was developed that can be integrated into animal housing by being freely suspended, thereby combining a small footprint with a physically robust design. The photobioreactor was coupled with the exhaust air of a chicken house to allow continuous cultivation of a mixed culture of Arthrospira spec. (Spirulina). Continuous quantification of CO2 and NH3 concentration showed that the coupled algae reactor effectively purifies the exhaust air from the chicken house while producing algal biomass. Typical production rates of greater than 0.3 g/l*day dry mass were obtained, and continuous operation was possible for several weeks. Morphological, biochemical, and genomic characterization of Spirulina cultures yielded insights into the dynamics and metabolic processes of the microbial community. We anticipate that further optimization of this approach will provide new opportunities for the generation of value-added products from gaseous CO2 and NH3 waste emissions, linking resource-efficient production of microalgae with simultaneous sequestration of animal emissions.Key points• Coupling a bioreactor with exhaust gases of chicken coop for production of biomass.• Spirulina mixed culture removes CO2 and NH3 from chicken house emissions.• High growth rates and biodiversity adaptation for nitrogen metabolism.Graphical abstractTowards a sustainable circular economy in livestock farming. The functional coupling of a helical tube photobioreactor with exhaust air from a chicken house enabled the efficient cultivation of Spirulina microalgae while simultaneously sequestering the animals’ CO2 and NH3 emissions.

Performance comparison of a photosynthetic and mechanically aerated microbial fuel cell for wastewater treatment and bioenergy generation using different anolytes

The use of expensive catalyst or mechanical aeration to carry out reduction reaction at cathode of conventional microbial fuel cell makes it costly and less efficient. Photosynthetic microbial fuel cell (PMFC) provides an option to overcome these issues by using microalgae as a biocatalyst at cathode chamber. This study aimed at assessing the performance of photosynthetic microbial fuel cell (PMFC) and its comparison with mechanically aerated MFC (MAMFC). The performance of both the systems was evaluated for two different anolytes namely, domestic wastewater and sugar industry wastewater. The PMFCs were inoculated with biocatalyst of Scenedesmus sp. in cathode chamber. Results showed that photosynthetic aeration significantly improved the efficiency of PMFCs as compared to MAMFCs. Maximum working voltage of 316 and 515 mV was achieved by PMFC with domestic wastewater and sugar wastewater, respectively, which was 15 % and 20 % higher than corresponding voltage of MAMFCs. Polarization and power curves showed that higher power density and lower internal resistance was achieved in PMFCs as compared to MAMFCs with both anolytes. Effect of light/dark regime on PMFCs resulted in a rise and drop pattern of dissolve oxygen and voltage generation. During light cycle, the average voltage was 214 mV and 370 mV for PMFC with domestic wastewater and sugar wastewater, respectively, which was 55 % and 54 % higher than corresponding dark cycle. Overall, the findings of the study suggested that PMFC support better power generation as compared to MAMFC, besides nutrients removal and production of algal biomass.

Implications of CO2 Sourcing on the Life-Cycle Greenhouse Gas Emissions and Costs of Algae Biofuels.

Production of algal biomass and its conversion to biofuels are important technological platforms within the larger umbrella of CO2 capture and utilization. This analysis incorporates a life-cycle assessment (LCA) with respect to global warming potential and techno-economic assessment (TEA) of algae biofuels, focusing on the sourcing and delivery of CO2. This analysis evolves past work in this area to include high-purity biogenic CO2, industrial fossil fuel use, fossil power plants, and direct air capture, and uses a Sherwood plot approach to estimate the CO2 capture energy penalty. We also show that allocation or displacement facilitates a more intuitive distinction between biogenic and fossil sources of carbon. Thus, the LCA better reflects the influence of coproduct handling strategies as compared to previous works. The TEA is also strongly influenced by the CO2 concentration in the flue gas. Currently, when CO2 is sourced from large-point sources, the price of biofuels ($4.5-6.5/GGE) may become comparable to fossil diesel. However, as DAC systems become more economical, they may deliver competitive CO2 sources for biofuels in 2050 with a total cost of <$7/GGE. Based on the net emissions and costs, algae biofuels with CO2 sourced from biogenic sources are consistent with a decarbonized economy as of now, with substantial potential for DAC with decreasing costs.

Comprehensive understanding of the regulatory mechanism by which selenium nanoparticles boost CO2 fixation and cadmium tolerance in lipid-producing green algae under recycled medium

Recycled medium plus cadmium is a promising technique for reducing the cultivation cost and enhancing the yield of microalgae lipids. However, oxidative stress and cadmium toxicity significantly hinder the resulting photosynthetic efficiency, cell growth and cell activity. Herein, selenium nanoparticles (SeNPs) were used to increase the total biomass, biolipid productivity, and tolerance to cadmium. Wide-ranging analyses of photosynthesis, energy yield, fatty acid profiles, cellular ultrastructure, and oxidative stress biomarkers were conducted to examine the function of SeNPs in CO2 fixation and cadmium resistance in Ankistrodesmus sp. EHY. The application of 15 μM cadmium and 2 mg L−1 SeNPs further enhanced the algal biomass productivity and lipid productivity to 500.64 mg L−1 d−1 and 301.14 mg L−1 d−1, respectively. Moreover, the rates of CO2 fixation, chlorophyll synthesis and total nitrogen removal were similarly increased by the application of SeNPs. Exogenous SeNPs strengthened cell growth and cadmium tolerance by upregulating photosynthesis, the TCA cycle and the antioxidant system, reducing the uptake and translocation of cadmium, and decreasing the levels of reactive oxidative stress (ROS), extracellular polymeric substances (EPSs) and cellular Cd2+ level in EHY under recycled medium and cadmium stress conditions. Additionally, a maximum energy yield of 127.40 KJ L−1 and a lipid content of 60.15% were achieved in the presence of both SeNPs and cadmium stress. This study may inspire the efficient disposal of recycled medium and biolipid production while also filling the knowledge gaps regarding the mechanisms of SeNP functions in carbon fixation and cadmium tolerance in microalgae.

Light intensity and spectral quality modulation for improved growth kinetics and biochemical composition of Chlamydomonas reinhardtii.

Effective strategies to optimize algal growth and lipid productivity are critical for the sustainable production of biomass for various applications. Light management has emerged as a promising approach, but the intricate relationship between light intensity, spectral quality, and algal responses remains poorly understood. This study investigated the effects of different light qualities (blue, red-orange, and white-yellow) and intensities (45-305 μmol/m2·s) on Chlamydomonas reinhardtii. Red-orange light exhibited the highest promotion of biomass growth and lipid productivity, with specific growth rates of 1.968 (d-1) and biomass productivity of 0.284 (g/L/d) at 155 μmol/m2·s and 205 μmol/m2·s, respectively. Within the intensity range of 205 μmol/m2·s to 305 μmol/m2·s, lipid mass fractions ranged from 10.5% w/w to 11.0% w/w, accompanied by lipid concentrations ranging from 68.6mg/L to 74.9mg/L. Red-orange light positively influenced carbohydrate accumulation, while blue light promoted protein synthesis. These findings highlight the importance of optimizing light quality and intensity to enhance algal biomass productivity and manipulate biochemical composition. Understanding the complex relationship between light parameters and algal physiology will contribute to sustainable algal cultivation practices and the use of microalgae as a valuable bioresource.

Viability of Reclaiming Municipal Wastewater for Potential Microalgae-Based Biofuel Production in the U.S.

Reclaimed municipal wastewater is a crucial component in biofuel production, especially in regions experiencing increasing freshwater scarcity. However, accurately estimating the potential for fuel production is challenging because of the uneven distribution of biofuel feedstock regions and wastewater treatment plants (WWTPs). This study assesses the viability of using reclaimed municipal water for algal biomass production in pond systems co-located with WWTPs under scenarios driven by biomass production and based on water transport logistics. We performed state- and county-level analysis of reclaimed water resources throughout the United States based on WWTP facility data. We overlaid these data onto estimated algae facility sites and examined the temporal resource availability to address seasonal variations in cultivation demand. Our findings reveal that 2694 billion liters per year of reclaimed water could potentially be used to produce 42.2 million metric tons (ash-free dry weight) of algal biomass, equivalent to 29.2 billion liters of renewable diesel equivalent (RDe). The use of reclaimed water would double current national water reuse and expand such reuse significantly in 455 counties across the United States. However, when we limit the construction of algae facilities to counties that can fully meet their water demand in order to minimize water transport burdens, the available supply decreases by 80%, to 512 billion liters, resulting in annual production of 12.2 billion liters of RDe, which still doubles current biodiesel production. Our analysis highlights the degree to which the location and flow of WWTPs and water transport affect the deployment of algae biofuel facilities and tradeoffs. These findings underscore the importance of improving the current WWTP infrastructure for reclaimed water reuse, especially in southern states.