Microalga Chlorella Vulgaris Research Articles

A commercial blend of macroalgae and microalgae promotes digestibility, growth performance, and muscle nutritional value of European seabass (Dicentrarchus labrax L.) juveniles.

Algae can leverage aquaculture sustainability and improve the nutritional and functional value of fish for human consumption, but may pose challenges to carnivorous fish. This study aimed to evaluate the potential of a commercial blend of macroalgae (Ulva sp. and Gracilaria gracilis) and microalgae (Chlorella vulgaris and Nannochloropsis oceanica) in a plant-based diet up to 6% (dry matter basis) on digestibility, gut integrity, nutrient utilization, growth performance, and muscle nutritional value of European seabass juveniles. Fish (11.3 ± 2.70 g) were fed with isoproteic, isolipidic, and isoenergetic diets: (i) a commercial-type plant-based diet with moderate fishmeal (125 g kg-1 DM basis) and without algae blend (control diet; Algae0), (ii) the control diet with 2% algae blend (Algae2), (iii) the control diet with 4% algae blend (Algae4), and (iv) the control diet with 6% algae blend (Algae6) for 12 weeks. The digestibility of experimental diets was assessed in a parallel study after 20 days. Results showed that most nutrients and energy apparent digestibility coefficients were promoted by algae blend supplementation, with a concomitant increase in lipid and energy retention efficiencies. Growth performance was significantly promoted by the algae blend, the final body weight of fish fed Algae6 being 70% higher than that of fish fed Algae0 after 12 weeks, reflecting up to 20% higher feed intake of algae-fed fish and the enhanced anterior intestinal absorption area (up to 45%). Whole-body and muscle lipid contents were increased with dietary algae supplementation levels by up to 1.79 and 1.74 folds in Algae 6 compared to Algae0, respectively. Even though the proportion of polyunsaturated fatty acids was reduced, the content of EPA and DHA in the muscle of algae-fed fish increased by nearly 43% compared to Algae0. The skin and filet color of juvenile European seabass were significantly affected by the dietary inclusion of the algae blend, but changes were small in the case of muscle, meeting the preference of consumers. Overall results highlight the beneficial effects of the commercial algae blend (Algaessence®) supplementation in plant-based diets for European seabass juveniles, but feeding trials up to commercial-size fish are needed to fully assess its potential.

Microplastics leachate may play a more important role than microplastics in inhibiting microalga Chlorella vulgaris growth at cellular and molecular levels

The leaching of microplastics (MPs) additives and their negative effects on aquatic organisms remain to be systematically elucidated. In this study, the toxicological effects of MPs leachate (micro-sized polyethylene (mPE) and micro-sized polyvinyl chloride (mPVC) acceleratedly leached by UVA for 15, 90, and 180 days in seawater) on microalga Chlorella vulgaris in terms of cell growth inhibition, oxidative stress, and transcriptomes were investigated. The leachate components of MPs aged for 90 days were further identified to elucidate the corresponding toxicity mechanisms of MPs on microalgal cells. The results revealed that both leachates of mPE and mPVC inhibited cell growth and increased oxidative stress in C. vulgaris, accompanied by a growth inhibition rate to microalgal cells of 4.0%–36.2% and 7.1%–48.2%, respectively. At the same mass concentration, the toxicological effects on C. vulgaris followed the order of mPVC leachate > mPE > mPE leachate > mPVC, whereas MPs leaching time indicated no change in MPs leaching toxicity. Furthermore, the gene functions of “translation, ribosomal structure and biogenesis” were mostly affected by MPs leachate. Compared to mPE leachate and pure MPs, the stronger inhibitory effects of mPVC leachate on microalgal cells may be attributed to the fact that more substances were leached from the polymer of mPVC, including Zn, farnesol isomer a, 2,6-di-tert-butyl-4-methylphenol, and acetyl castor oil methyl ester. In summary, this study provides a better understanding of the ecotoxicological influences of MPs and MPs leachate, and offers a warning on the ecological risk caused by plastic additives.

Differences and Similarities in Lipid Composition, Nutritional Value, and Bioactive Potential of Four Edible Chlorella vulgaris Strains.

The microalga Chlorella vulgaris is a popular food ingredient widely used in the industry, with an increasing market size and value. Currently, several edible strains of C. vulgaris with different organoleptic characteristics are commercialized to meet consumer needs. This study aimed to compare the fatty acid (FA) and lipid profile of four commercialized strains of C. vulgaris (C-Auto, C-Hetero, C-Honey, and C-White) using gas- and liquid-chromatography coupled to mass-spectrometry approaches, and to evaluate their antioxidant and anti-inflammatory properties. Results showed that C-Auto had a higher lipid content compared to the other strains and higher levels of omega-3 polyunsaturated FAs (PUFAs). However, the C-Hetero, C-Honey, and C-White strains had higher levels of omega-6 PUFAs. The lipidome signature was also different between strains, as C-Auto had a higher content of polar lipids esterified to omega-3 PUFAs, while C-White had a higher content of phospholipids with omega-6 PUFAs. C-Hetero and C-Honey showed a higher content of triacylglycerols. All extracts showed antioxidant and anti-inflammatory activity, highlighting C-Auto with greater potential. Overall, the four strains of C. vulgaris can be selectively chosen as a source of added-value lipids to be used as ingredients in food and nutraceutical applications for different market needs and nutritional requirements.

Oxygen and nitrogen-doped carbon particles derived from pyrolysis of Chlorella vulgaris and Spirulina platensis microalgae as an efficient electrode material for supercapacitor application

This study consists of the thermal activation of Chlorella vulgaris and Spirulina platensis microalgae with a potassium hydroxide (KOH) chemical agent in a carbon dioxide (CO2) atmosphere and the formation of nitrogen and oxygen-doped material from the hydrothermal interaction of the obtained activated carbons with nitric acid. The obtained nitrogen and oxygen-doped activated carbons were used in the production of electrochemical super capacitors. The morphological properties of the obtained pores were evaluated by transmission electron microscopy (TEM). Electrochemical properties were evaluated according to the cyclic voltammetry (CV) method in sulphuric acid (H2SO4), potassium chloride (KCl), and sodium hydroxide (NaOH) electrolytes with a scanning rate in the range of 2.5–50 mVs−1. Nitrogen and oxygen doped electrode electrochemical capacitor based on Spirulina platensis microalgae showed the highest specific capacitance of 99.53 Fg−1 at a scanning rate of 2.5 mV s−1 in 1 M H2SO4 electrolyte. In contrast, the supercapacitor based on an activated carbon electrode from Chlorella vulgaris microalgae showed the highest specific capacitance of 156.04 Fg−1 at a scan rate of 2.5 mV s−1 in 1 M KCl electrolyte.

Influence of Light Color on Power Generation and Microalgae Growth in Photosynthetic Microbial Fuel Cell with Chlorella Vulgaris Microalgae as Bio-Cathode

Photosynthetic microbial fuel cell (PMFC) is an environmentally friendly sustainable technique for simultaneous wastewater treatment and power recovery. PMFC utilizes the microalgae to generate oxygen by photosynthesis process in the biocathode. Light sources and intensities have direct effect on chlorophyll pigment formation, photosynthesis processes and microalgae growth. In this study, Chlorella vulgaris was utilized as biocathode in PMFC fed with actual slaughterhouse wastewater. The biocathode was illuminated with florescent light as well as yellow, red and blue LED lights with light intensities of 67.46, 47.03, 26.18 and 4.70µmol/m.s, respectively. Power output and microalgae growth were considered in evaluating the PMFC performance. Results demonstrated that the highest power output was 217.04 mW/m2 generated under florescent light compared to 28.41, 171.08, and 21.65 mW/m2 observed under yellow, red and blue LEDs, respectively. Additionally, statistical analysis was performed using fifth-degree polynomial model which fitted well the experimental data with a determination coefficient (R2) > 0.97. The results reflected a high confidence level in depicting the growth mechanism of Chlorella vulgaris under lighting sources with different light colors and intensities.

Use of Microbially Treated Olive Mill Wastewaters as Soil Organic Amendments; Their Short-Term Effects on the Soil Nematode Community

Managing olive mill wastewater (OMW) is a major environmental problem. We followed two methods for OMW bioremediation: one with the white-rot fungus Pleurotus ostreatus alone and one with the fungus plus the microalga Chlorella vulgaris. To evaluate the potential use of both final products as soil amendments, in a pot experiment, we applied treated OMW to soil cultivated with Lactuca sativa, and we studied their short-term effects on the soil nematode community in terms of trophic and functional structure, metabolic footprint, genera composition, and interaction networks. We also applied non-treated OMW and simply water (control). The addition of non-treated OMW significantly reduced the abundance of all nematodes, and the network of interactions was the most fragmented and the least robust against future disturbance. The effect on trophic group abundances was similar but less pronounced when OMW was previously detoxified either by the fungus alone or by its combination with the alga. In the latter case, the phytoparasites were suppressed but the bacterivorous nematodes were not affected. However, the most cohesive and robust nematode network was formed in the soil that received the fungal-treated OMW. None of our OMW applications significantly changed community composition, none improved the already degraded status of the soil food web—which is attributed to the sandy texture of our soil—and none affected the growth of lettuce plants, perhaps because of the short duration of the experiment (30 days). Thus, our future research will aim to estimate the long-term impact of OMW.

Iron oxide nanoparticles derived from Chlorella vulgaris extract: Characterization and crystal violet photodegradation studies

Nanoparticles were first used a century ago, but have recently gained popularity due to their ease of use, eco-friendliness, pollution-free nature, nontoxicity and low cost for wastewater treatment applications. In terms of nanoparticles preparation, green synthesis is a more convenient, economical, quick, and environmentally friendly process than traditional synthesis (i.e. chemical and mechanical) methods. The objective of this study was to synthesise iron oxide nanoparticles from iron (III) chloride using microalgae (Chlorella vulgaris) extract for photodegradation of crystal violet (CV) dye. Various characterization methods such as X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and Fourier-transform infrared spectroscopy (FTIR) were used to examine properties of the nanoparticles including its crystallinity, morphologies and sizes, and functional groups, respectively. The CV photodegradation process was carried out under different process conditions included initial CV concentration (10 mg/L – 25 mg/L), CV solution pH (5.39 – 8.98), and irradiation period (30 – 90 mins) to investigate the optimum operating conditions for the CV removal. The analysis using FESEM demonstrated that the nanoparticles exhibited irregularities and cylindrical shapes, measuring 109 nm in size. Meanwhile, the XRD analysis indicated that the iron oxide nanoparticles possessed a tetragonal crystal structure. The presence of Fe-O stretching vibrations at 486 cm-1 was confirmed by the FTIR spectrum. In terms of CV photodegradation studies, the optimum operating conditions for CV removal using iron oxide nanoparticles were determined to be at initial CV concentration of 10 mg/L, solution pH of 8.98, and an irradiation period of 90 mins, with a percentage removal of 96.21 %.

Sediment-seawater exchange altered adverse effects of ocean acidification towards marine microalgae

Ocean acidification (OA) exhibits high threat to marine microalgae. However, the role of marine sediment in the OA-induced adverse effect towards microalgae is largely unknown. In this work, the effects of OA (pH 7.50) on the growth of individual and co-cultured microalgae (Emiliania huxleyi, Isochrysis galbana, Chlorella vulgaris, Phaeodactylum tricornutum, and Platymonas helgolandica tsingtaoensis) were systematically investigated in the sediment-seawater systems. OA inhibited E. huxleyi growth by 25.21 %, promoted P. helgolandica (tsingtaoensis) growth by 15.49 %, while did not cause any effect on the other three microalgal species in the absence of sediment. In the presence of the sediment, OA-induced growth inhibition of E. huxleyi was significantly mitigated, because the released chemicals (N, P and Fe) from seawater-sediment interface increased the photosynthesis and reduced oxidative stress. For P. tricornutum, C. vulgaris and P. helgolandica (tsingtaoensis), the growth was significantly increased in the presence of sediment in comparison with those under OA alone or normal seawater (pH 8.10). For I. galbana, the growth was inhibited when the sediment was introduced. Additionally, in the co-culturing system, C. vulgaris and P. tricornutum were the dominant species, while OA increased the proportions of dominant species and decreased the community stability as indicated by Shannon and Pielou's indexes. After the introduction of sediment, the community stability was recovered, but remained lower than that under normal condition. This work demonstrated the role of sediment in the biological responses to OA, and could be helpful for better understanding the impact of OA on marine ecosystems.

In Vitro Studies on Rumen Fermentation and Methanogenesis of Different Microalgae and Their Effects on Acidosis in Dairy Cows

Two in vitro studies were carried out on nonlactating dairy cows. Experiment 1 compared the methanogenesis and rumen fermentation parameters of various microalgae (Spirulina platensis, Chlorella vulgaris, and Schizochytrium spp.) and protein feeds (sunflower meal, soybean meal, and alfalfa hay) with monensin (MON). Rumen fermentation parameters were determined by an in vitro gas production system. Experiment 2 compared the ability of three microalgae to prevent acidosis. They were tested for 6 h against oat straw (100 mg) and MON (12 g/mL) to ameliorate ruminal acidosis caused by the addition of glucose (0.1 g/mL) as a fermentable carbohydrate with rumen fluid. In experiment 1, there were variations in the nutrient content of microalgae and protein sources. The dry matter content of the substrates ranged from 90 to 94%, and the organic matter content ranged from 82 to 88%, with Schizochytrium spp. having the highest. Protein content in algae and protein feeds ranged from 18–62% of dry matter (DM) to 16–48% DM, with S. platensis and C. vulgaris having the highest. The ether extract of Schizochytrium spp. (45.5% DM) was the highest of any substrate. In vitro rumen fermentation revealed that protein feeds increased the cumulative gas production at the highest level while MON caused a decrease. Ruminal pH was found to be higher in MON (6.95) and protein feeds (6.77–6.81) than in algae (6.37–6.50). In addition, in terms of metabolizable energy and digestible organic matter, protein feeds outperformed algae. The MON produced the least amount of methane (CH4) of any substrate, but Schizochytrium spp. demonstrated potential for CH4 reduction. In these groups, the decrease in CH4 production was accompanied by a decrease in total volatile fatty acids, acetate, and the acetate-to-propionate ratio, but an increase in propionate. Experiment 2 revealed MON as the most effective cure for controlling acidosis. However, C. vulgaris and Schizochytrium spp. had an effect on medium culture pH and demonstrated potential for acidosis prevention. This study found that algae can influence ruminal fermentation, have the potential to reduce CH4 production, and may reduce acidosis incidence rates. These assumptions, however, must be validated through in vivo studies.

Analysis of Microalgal Density Estimation by Using LASSO and Image Texture Features.

Monitoring and estimating the density of microalgae in a closed cultivation system is a critical task in culturing algae since it allows growers to optimally control both nutrients and cultivating conditions. Among the estimation techniques proposed so far, image-based methods, which are less invasive, nondestructive, and more biosecure, are practically preferred. Nevertheless, the premise behind most of those approaches is simply averaging the pixel values of images as inputs of a regression model to predict density values, which may not provide rich information of the microalgae presenting in the images. In this work, we propose to exploit more advanced texture features extracted from captured images, including confidence intervals of means of pixel values, powers of spatial frequencies presenting in images, and entropies accounting for pixel distribution. These diverse features can provide more information of microalgae, which can lead to more accurate estimation results. More importantly, we propose to use the texture features as inputs of a data-driven model based on L1 regularization, called least absolute shrinkage and selection operator (LASSO), where their coefficients are optimized in a manner that prioritizes more informative features. The LASSO model was then employed to efficiently estimate the density of microalgae presenting in a new image. The proposed approach was validated in real-world experiments monitoring the Chlorella vulgaris microalgae strain, where the obtained results demonstrate its outperformance compared with other methods. More specifically, the average error in the estimation obtained by the proposed approach is 1.54, whereas those obtained by the Gaussian process and gray-scale-based methods are 2.16 and 3.68, respectively.

Technological Evaluation of Algae-Based Fillers for Polymer 3D Printing

One approach to reducing the environmental footprint of conventional polymers is to compound them with bio-based fillers. Plant-based materials have already been successfully used as polymer fillers. In this context, algae-based fillers received minor attention. Due to their unique growth efficiency and ability to capture large amounts of CO2, the use of algae-based fillers could have economic and ecologic advantages. In this work, a possible use of algae as a sustainable filler for filament materials was technologically evaluated. In practical investigations, conventional polyethylene-terephthalate-glycol (PETG) was mixed with the microalgae spirulina platensis and chlorella vulgaris and extruded to 3D printing filaments. Based on printed test specimens and material samples, the printability, mechanical, and thermal properties of the composite were determined. Filaments with a homogeneous distribution of algae particles and stable diameters up to a filler content of 30 wt.% could be produced. All filaments had good printability and adequate moisture sensitivity for higher algae contents. For 30 wt.% the tensile strength of the produced filaments decreases from 54 MPa to 24 MPa, the flexural strength decreases from 87 MPa to 69 MPa, and the material operating temperature decreases slightly from 70 °C to 66 °C. The addition of smaller amounts of algae results in minor changes regarding the overall performance. The properties of the material were comparable to those of other natural fillers such as wood, bamboo or cork. The main objective of adding bio-based materials to polymeric matrices can be achieved. Our results suggest that algae-based filaments can be produced as a more sustainable and low-cost material.

Replacing expensive synthetic media with banana stem compost extract medium for production of Chlorella vulgaris

ABSTRACT Microalgal cultivation by small scale aquaculture farmers is limited by the high cost of synthetic culture media. The current study was conducted to investigate use of banana stem compost extract (BSCE) as an alternative medium for cultivation of the microalga Chlorella vulgaris. C. vulgaris was batch cultured for 24 days in the laboratory using synthetic Bold Basal Medium (BBM) as a control and BSCE at concentrations of 2%, 5% and 10% (by volume) as the treatments. Algal growth was evaluated by measuring dry cell weight and specific growth rate (SGR) during the experimental period. Chemical composition was analysed following standard analytical methods. Variations in growth trends among culture media were attributed to variations in nutrient concentration and lack of acclimatization period. Some macro- and micronutrients in BSCE-cultivated C. vulgaris were higher than or similar to those observed in BBM-cultivated algae. The macronutrients differed among BSCE treatments. It was concluded that BSCE can be used as the culture medium, providing similar nutritional value and supporting similar growth performance to synthetic media. However, selection of BSCE concentration should be based on macronutrients and take into account the intended use of cultivated microalgae.

Biofertilizers Improve the Leaf Quality of Hydroponically Grown Baby Spinach (Spinacia oleracea L.)

Plant nutrition through mineral fertilizers is commonly used in soilless culture systems. Our study aims to replace intensive mineral fertilizers with bio-fertilizers, at least partially. We supplemented 50% of the mineral fertilizers with Chlorella vulgaris microalgae, a mix of beneficial bacteria and mycorrhiza. In addition, we investigated how to enhance spinach quality by implementing a sustainable and eco-friendly production method. Our research focused on analyzing the parameters of leaf quality and nitrate accumulation of baby spinach grown in a floating culture system utilizing biofertilizers. When mycorrhiza, algae, and bacteria supplemented 50% of mineral fertilizers, 17.5%, 20%, and 21.9% fewer leaf yields than 100% mineral fertilizers (5270 g m−2) were achieved. However, biofertilizers improved the internal leaves’ quality of hydroponically grown baby spinach. The highest amount of total phenolic (356.88 mg gallic acid 100g−1), vitamin C (73.83 mg 100 g−1), total soluble solids (9.4%), phosphorus (0.68%), and iron (120.07 ppm) content were obtained by using mycorrhiza. Bacteria induced the lowest nitrate content (206 mg kg−1) in spinach leaves, while 100% mineral fertilizers showed the highest nitrate (623 mg kg−1) concentration. Moreover, bacteria provided the highest SPAD-chlorophyll (73.72) and titrable acidity (0.31%). The use of microalgae, Chlorella vulgaris, induced the highest amount of potassium (9.62%), calcium (1.64%), magnesium (0.58%), zinc (75.21 ppm), and manganese (64.33 mg kg−1). In conclusion, our findings demonstrate that the utilization of biofertilizers has the potential to significantly reduce the reliance on mineral fertilizers by up to 50%. Furthermore, an improvement in the quality of baby spinach, as evidenced by an increase in health-beneficial compounds, is possible. Thus, implementing biofertilizers in the cultivation of soilless baby spinach presents a promising approach to achieving both environmental sustainability and improved crop quality.

A Study of the Processes of the Cultivation and Useful Products Accumulation by the Microalgae Chlorella vulgaris in a Photobioreactor with a Fiber-Optic Lighting System

The microalgae Chlorella vulgaris is cultivated in a thin-layer tubular photobioreactor with a unique design illuminated by a side-glow optical fiber. As a result of applying a method of intensive prototyping, the optimal design of the photobioreactor is found, and the maximum growth rate of 32 mg/L/day is achieved (against 8 mg/L/day in the case of control cultivation in a luminostat). The total protein content in the biomass obtained from the unit is 21 ± 6%, which is slightly lower when compared to the control (26 ± 6%); however, the revealed differences are not statistically significant. In addition, the levels of saturated palmitic (C16:0) and unsaturated linoleic (C18:2) and α-linolenic (C18:3α) fatty acids are increased in the biomass samples from the photobioreactor in comparison with the control cultivation. Thus, the potential of using a photobioreactor with the developed design for obtaining a nutrient biomass of the microalgae C. vulgaris for the life-support systems of crewed spacecraft is shown.

Assessing OBT formation and enrichment: ROS signaling is involved in the radiation hormesis induced by tritium exposure in algae.

Tritium is the main component of radioactive wastewater from nuclear power plants and can be migrated into organisms to form organically bound tritium (OBT), which may pose a potential risk to aquatic ecosystem. Hence, it is essential to monitor OBT conversion in the presence of tritium exposure. In this study, the effects of pretreatment methods such as digestion on the recovery of tritium were discussed. It was found that microwave digestion pretreatment could improve the recovery of tritium by up to 90 % and allow OBT measurement with a small sample size equivalent to about 60mg (dry weight). In addition, the efficiency of OBT transformation was different among biological samples, and the radiation hormesis phenomenon was induced by tritium exposure (3.7× 106 Bq/L) in microalgae Chlorella vulgaris（C. vulgaris）. The tritium exposure may induce radiation hormesis through the reactive oxygen species (ROS) signaling pathway, thus improving the photosynthetic capacity and metabolism level of C. vulgaris. Furthermore, enhancement of photorespiration metabolism and the antioxidation system may be important means for C. vulgaris to balance damage by tritium radiation. This study provides insights for further investigating OBT behavior, and will contribute to understanding the equilibrium damage mechanism of algae exposed to tritium.

Simultaneous Cultivation of Microalgae Chlorella vulgaris with a Polymer Material Based on Chitosan for the Sorption of Heavy Metals and Biomass

One of the most important problems today is the eutrophication of water bodies, caused by an excess of nutrients, primarily nitrogen and phosphorus. The pollution of water bodies is also aggravated by heavy metals contained in wastewater. In this paper, we consider the joint purification of water from an excess amount of microalgae biomass Chlorella vulgaris and heavy metals using polymer materials based on chitosan. Large-angle X-ray diffraction analysis of the samples was performed at the BioMUR station of the Kurchatov Synchrotron.

3D Printing Using Iota-Carrageenan-Based Hydrogel with Immobilized Chlorella vulgaris Microalgae

Based on a study of the temperature dependence of the gelation process of aqueous carrageenan solutions, we determine the technological parameters for curing hydrogel “ink” based on carrageenan-polysaccharide solutions. With the aim of designing a material as an additional source of oxygen and a means of rehabilitating polluted waters in closed ecosystems, the possibility of the 3D bioprinting of matrix structures containing immobilized cells of Chlorella vulgaris microalgae is demonstrated.

On the Stable Operation of a Membraneless Microbial Fuel Cell for More Than One Hundred Days

The development of alternative energy sources is one of the most important areas of modern science. The processes of energy generation are studied in a membraneless mediatorless microbial fuel cell fueled by the Gluconobacter oxydans microorganism using synthetic wastewater with phototrophic Chlorella vulgaris microalgae in the cathode chamber. The operation of the fuel cell is compared with different catholytes, including microalgae with and without illumination, a nutrient medium for growing microalgae, and a K-phosphate buffer. This microbial fuel cell shows stable operation with a slight decrease in power over 113 days of the experiment. This result is due to the formation of biofilms and is confirmed by scanning-electron-microscopy images. Thus, the studied microbial fuel cell is promising for further study in the field of wastewater treatment.

Impact of Perfluorocarbons with Gas Transport Function on Growth of Phototrophic Microorganisms in a Free and Immobilized State and in Consortia with Bacteria

The effects of the presence of perfluorocarbons (PFC) with a gas transport function in media with different phototrophic microorganisms on their growth rates and the accumulation of their biomass when using free and immobilized cells as inoculums were investigated. The significant increase in the average rate of biomass accumulation as well as levels of biomass accumulation in the presence of various PFCs were established for Chlorella vulgaris cells. When 1 g/L glycerol was introduced into the growth medium with PFCs and C. vulgaris cells, the increase in the rate of biomass accumulation was 9–32%. The maximum intracellular ATP concentrations corresponded to the combination of microalgae (Chlorella vulgaris) with bacterial cells (Pseudomonas esterophilus and Rhodoccus ruber) obtained with a mass ratio of 25:1. It provided for the formation of a consortium, which was able to accumulate the maximum amount of microalgae biomass for 3 days in the medium with PFCs and organophosphorus pesticide. The obtained data allow, on the one hand, predicting the growth of microalgae under environmental conditions in media with PFC pollution and, on the other hand, developing approaches to regulation of phototrophic microorganisms’ growth in order to obtain and use their high biomass yields for various purposes.

Optimal Co-pyrolysis of municipal sewage sludge and microalgae Chlorella Vulgaris: Products characterization, synergistic effects, mechanism, and reaction pathways

Co-pyrolysis of municipal sewage sludge (MSS) and microalgae Chlorella Vulgaris (MCV) was carried out in a fixed-bed reactor to investigate the effect of feedstocks interaction on pyrolysis products and synergistic effects. Based on previous authors' research, the optimum values of reaction parameters were T = 520 °C, mixing ratio (MCV/MSS) = 0.82, and an inert gas flow rate of 0.55 L/min. For the investigation of synergetic effects at optimum point, theoretical values anticipated from each characteristic were computed as an arithmetic sum of the single pyrolysis values obtained. For the first time, by using GC analysis, changes in gas components (H2, CO, CO2, CH4) at different temperatures (220–520 °C) and reaction times (0–30 min) have been investigated. Referring to GC-MS results the percentages of oxygen-containing species, alkanes, alkenes, aliphatic, aromatic, and total hydrocarbons were changed from the theoretical value of (41.719%), (6.004%), (11.215%), (17.219%), (4.317%), and (21.536%) to experimental value (39.292%), (3.693%), (12.103%), (15.796%), (0%), and (15.796%) respectively. Fatty acids and N&O-containing compounds (amides) were increased from (12.297%) to (26.009%) and (6.989%) to (16.217%), respectively. Co-pyrolysis bio-oil was rich in fatty acids and amides compounds. So, co-pyrolysis of sewage sludge and Chlorella Vulgaris provides a new orientation for high value-added utilization of biomass. It was observed that the nitrogen and oxygen content of biochar was reduced (0.29% and 1.01% respectively) compared to the theoretical condition. In the end, a comprehensive mechanism, synergistic, and reaction pathways of co-pyrolysis of MCV and MSS were presented.