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1.
Water Res ; 174: 115642, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32114019

RESUMO

Phytoremediation of reverse osmosis concentrate (ROC) with microalgae can simultaneously achieve multi-functions of ROC treatment, CO2 mitigation and microalgae biolipid production. But the performances are usually inhibited by high free ammonia nitrogen (FAN) concentration and chromaticity of ROC. To offset these negative effects, an integrated technique including electrooxidation pretreatment and Chlorella vulgaris remediation was proposed, in which the ROC was first pretreated with electrooxidation to decrease FAN and chromaticity, and then the oxidized ROC was remediated with microalgae to reclaim nutrients and produce biolipid. Results showed that FAN was sharply reduced from 53.0 mg N/L to 13.9 mg N/L and chromaticity was decreased from 1600 to 100 Pt-Co via electrooxidation. Possible reaction mechanism of nutrients removal was discussed via electron mass balance. Explanation on chromaticity decrease was revealed by analyzing humic acid conversion path with fluorescence characteristics. During microalgae remediation process, nutrients removal rate, microalgae biomass concentration and lipid yield were effectively enhanced in electrooxidized ROC. Energy balance analysis indicated that microalge lipid energy under current density of 3.25 mA/cm2 basically compensated total input energy despite ROC sterilization. This work provided a promising strategy for large-scale ROC treatment and microalgae biolipid production.


Assuntos
Chlorella vulgaris , Microalgas , Biomassa , Nitrogênio , Osmose , Águas Residuárias
2.
Bioresour Technol ; 304: 123061, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32127245

RESUMO

Selection of indigenous and potential algal strain with high lipid content is paramount challenge in the avenues of microalgal biodiesel production. Particularly, hyper lipid producing algae with maximal triacyglycerols (TAGs) content and preferable fatty acid composition is of interest for sustainable biodiesel. Hence, the present study on comparative assessment of Chlorella vulgaris, Scenedesmus sp. and Synechococcus sp. was done in terms of cell density, lipid, TAGs and fatty acid. Higher biomass yield was obtained in Chlorella vulgaris (0.54 gL-1) on 13th day while maximal lipid content of 36% was observed in Scenedesmus sp. followed by Chlorella vulgaris (33%). Lipidomic analysis revealed higher non-polar lipids inChlorella vulgaris (57%) and Scenedesmus sp. (54%), whereas in Synechococcus sp. 69% polar lipids were present. In fatty acid profile, C24:0 (22.11%) was predominant in Chlorella vulgaris, while C20:0 (31.72%) and C18:2 (22.26%) was prevalent in Scenedesmus sp. and Synechococcus sp. respectively.


Assuntos
Bioprospecção , Chlorella vulgaris , Microalgas , Biocombustíveis , Biomassa , Contagem de Células , Ácidos Graxos , Seleção de Pacientes
3.
Ultrasonics ; 103: 106067, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32018093

RESUMO

Controlled capture of single biological micro particles, with effective capture function, little heat damage to and good stability of captured samples simultaneously, has been a technological challenge in the area of micro manipulation. This paper presents an ultrasonic tweezers based new strategy to meet the challenge. In the strategy, being different from the other ultrasonic methods, the MMP (micro manipulating probe), which vibrates elliptically, is in contact with the substrate. Single yeast cells with a diameter of 3-7 µm and Chlorella vulgaris powders with a diameter of 2-10 µm near the MMP can be sucked onto the MMP's tip. The captured particle can be transferred to a desired location at the interface between the water film and substrate by moving the ultrasonic tweezers. The temperature rise in the capture region is less than 0.1 °C, and the sucking distance can be up to 20 µm. The captured particle is in contact with the MMP's tip, which results in a good stability of the captured particle. The experiments also show that it is possible to use multiple MMPs to individually capture single cells. The finite element analyses indicate that acoustic radiation force generated by the ultrasonic field around the MMP is responsible for the capture. Moreover, the effects of the orthogonal vibration components, tilt angle and length of the MMP on the capture capability are clarified.


Assuntos
Micromanipulação/instrumentação , Ultrassom/instrumentação , Chlorella vulgaris , Desenho de Equipamento , Análise de Elementos Finitos , Tamanho da Partícula , Pós , Temperatura Ambiente , Transdutores , Vibração , Água , Leveduras
4.
Bioresour Technol ; 302: 122793, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32007846

RESUMO

This study investigates enhanced biogas production via co-Hydrothermal gasification (co-HTG) of wet Chlorella vulgaris biomass and hydrochar (HC). Hydrothermal carbonization was applied to valorize struvite containing waste microalgae stream into solid bio-fuel with improved combustion properties. The effects of HC quality and mixing ratio are investigated on biogas yield, composition and carbon conversion ratio. The results show that the application of blending components promotes H2, CH4 formation and selectivity in hydrothermal gasification. The total co-HTG gas yield is increased from 19.13 to 46.95 mol kg-1 at 650 °C and 300 bar by applying 5 wt% HC blending concentration and reduced level of volatile matter content (24.61 wt%). The obtained high hydrogen, methane yields and carbon conversion ratio (19.49, 2.98 mol kg-1, 82.31%, respectively) indicate effective hydrothermal upgrading potentials in case of wet and waste biomass feedstocks.


Assuntos
Biocombustíveis , Chlorella vulgaris , Biomassa , Carbono , Temperatura Ambiente
5.
Bioresour Technol ; 302: 122891, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32008861

RESUMO

Photo-bioreactor experiments using three different size beads (2.0, 3.5, and 5.0 mm) immobilized with two different types of microalgae namely Chlorella vulgaris and Chlamydomonas reinhardtii were conducted to evaluate the nutrient removal efficiency. The highest nutrient removal was obtained at gel bead pore size of 3.5 mm for both species of C. vulgaris and Ch. reinhardtii. 95% removal of T-N and complete reduction of T-P were achieved within 3 stages of treatment in photo-bioreactors containing 20% algal bead volume fraction. Moreover, the results observed by confocal laser scanning microscopy (CLSM) using SYTOX red dye and SYTOX green dye in alginate beads indicated that the effective depth of C. vulgaris and Ch. reinhardtii was about 3.6 mm and 3.0 mm, respectively. This optimized cell immobilization technology would accelerate the nutrient uptake rate of microalgae for improving efficiency of wastewater treatment systems.


Assuntos
Chlamydomonas reinhardtii , Chlorella vulgaris , Microalgas , Alginatos , Nutrientes , Águas Residuárias
6.
Bioresour Technol ; 304: 123012, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32085903

RESUMO

To explore the energy barrier between microalgae cells that impedes their aggregation and their interfacial interactions with cationic starch (CS), this study applied the extended Derjaguin Landau Verwey Overbeek (eDLVO) theory combined with the flocculation performance to analyze the interactions. The result shows that zeta potential based electrostatic interaction played a determinative role no matter for the energy barrier or the interfacial interactions. The energy barrier between microalgae cells would decrease with the descend of the pH and it disappeared when the pH decreased to 3 and resulted in self-flocculation. The quantitative analysis of the interfacial interactions between microalgae cell and CS showed well agreement with the experiment data of flocculation efficiency (FE) under different conditions of pH and ionic strength. Thus, the quantitative findings will be helpful to know the aggregation and flocculation process better and find more effective flocculants for microalgae harvesting.


Assuntos
Chlorella vulgaris , Microalgas , Biomassa , Floculação , Concentração de Íons de Hidrogênio , Concentração Osmolar , Amido
7.
Sci Total Environ ; 713: 136374, 2020 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-31955073

RESUMO

Harmful algal blooms (HABs) are serious problems in landscape waters sourced from reclaimed water. In this study, the suppression effects of UV-C irradiation on microalgal growth were researched to find a possible preventive approach. Microcystis aeruginosa and Chlorella vulgaris were exposed to UV-C irradiation and then cultured in real reclaimed water for 7-18 d. UV-C irradiation at 50-200 mJ cm-2 could inhibit the growth of M. aeruginosa, C. vulgaris, and both microalgae in co-culture for 3-14, 1-3, and 1-5 d respectively. In addition, UV-C irradiation could cause damage to the cell integrity. At 100-200 mJ cm-2 UV-C, the proportion of microalgal membrane damage (Pmd) in M. aeruginosa cells increased rapidly to 56%-76% from day 3, whereas that in C. vulgaris cells increased to 23%-62% within 3 d. The photochemical efficiency (represented by Y value) of the irradiated groups was negatively affected immediately after UV-C irradiation and recovered gradually during the incubation. The Y value of M. aeruginosa cells began to recover from days 3 to 14, whereas that of C. vulgaris recovered much more quickly, from days 0.1 to 1. Overall, the irradiation-induced suppressive effects on algal growth correlated positively with the UV-C doses. Because M. aeruginosa was more sensitive to UV-C irradiation, UV-C irradiation not only controlled the total biomass of the mixed algae but also selectively reestablished the dominance of the nontoxic C. vulgaris.


Assuntos
Chlorella vulgaris , Microcystis , Técnicas de Cocultura , Proliferação Nociva de Algas , Raios Ultravioleta
8.
Chemosphere ; 242: 125119, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31677511

RESUMO

Many industries located in coastal areas use a large amount of seawater. Algal biofouling can be a major problem that hinders the efficiency of these industrial facilities. In most cases, seawater requires algal removal pre-treatment to avoid or mitigate biofilm formation. To remediate green microalgae, Fe2O3-TiO2 nanoparticles with 2.5% w/w Fe2O3 were applied as a visible light driven photocatalyst. The anti-algal activity of the photocatalytic pre-treatment using green microalgae, Chlorella vulgaris was tested. The experiments were carried out in freshwater, artificial seawater, and real seawater. Effect of photocatalyst dosage, visible light intensity, and water salinity on the removal of microalgae was investigated. The highest inactivation efficiency of Chlorella vulgaris was achieved under 55 W/m2 visible light irradiation when 0.25 g/L of Fe2O3-TiO2 photocatalyst was used. The photocatalytic removal kinetics of Chlorella vulgaris followed the pseudo first order Langmuir-Hinshelwood model. The results revealed that the efficiency of photocatalytic removal of algae decreased with increasing of seawater salinity. The anti-algal activity of Fe2O3-TiO2 nanoparticles was attributed to the generation of reactive oxygen species (ROS) through the photocatalytic process. H+ radical was shown to be the most important ROS that nanoparticles produced in the aqueous media. Using Fe2O3-TiO2 nanoparticles in photocatalytic pre-treatment could be an efficient environmental-friendly method for micro-algal remediation in seawater under visible light.


Assuntos
Chlorella vulgaris/efeitos dos fármacos , Desinfetantes/toxicidade , Luz , Incrustação Biológica , Compostos Férricos/química , Água Doce , Cinética , Microalgas , Nanopartículas , Processos Fotoquímicos , Salinidade , Água do Mar/química , Titânio/química , Água
9.
Environ Technol ; 41(5): 617-626, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30074855

RESUMO

The microalgae Chlorella vulgaris ATCC 13482 was used in the present study for municipal wastewater treatment. Batch experiments were performed in bubble column photobioreactors of 7 L working volume maintained at 25 ± 2°C and 14 h/10 h of photo and dark cycle. The treatment process was enhanced by using CO2-augmented air (5% CO2 v/v) supply into the microalgal culture in comparison to the use of normal air (0.03% CO2 v/v). For a period of 7 days, C. vulgaris effected maximum removals of 74.4% soluble fraction of chemical oxygen demand, 72% ammonia (NH4-N), 60% nitrate (NO3-N) and 81.93% orthophosphate (PO4-P) with use of normal air, whereas 84.6% sCOD, 88% NH4-N, 72% NO3-N and 92.8% PO4-P removals, respectively, with use of 5% CO2/air supply. Using kinetic study data, the specific rates of ammonia and phosphate uptake (qammonia and qphosphate) by C. vulgaris at 5% CO2/air supply were found to be 2.41 and 0.85 d-1, respectively. Using the algal remediation technology, nitrogen-phosphorus-potassium recovery from sewage treatment plant of 37.5 million litres per day wastewater influent capacity was calculated to be ∼298.5, 55.4 and 83.7 kg d-1, respectively.


Assuntos
Chlorella vulgaris , Microalgas , Biomassa , Dióxido de Carbono , Nitrogênio , Nutrientes , Fotobiorreatores , Águas Residuárias
10.
Environ Technol ; 41(3): 267-276, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29963975

RESUMO

Conventional treatments for nutrient removal in wastewater are shifting to Anaerobic Membrane Bioreactors, which produce a high-quality effluent with minimum sludge production. The effluent resulting contains high nitrogen and phosphorus load that can be eliminated by microalgae culture. The aim of this study is to evaluate the ammonium and phosphorus removal rate of different microalgae species in the effluent of an anaerobic treatment. For that, 4 different microalgae species have been tested (Chlamydomonas reinhardtii, Scenedesmus obliquus, Chlorella vulgaris and Monoraphidium braunii) in batch monoculture and mixed conditions. Results indicate that all species are able to eliminate both P and N in the medium with high removal rates. However, a slight interspecies competition may boost these removal rates and productivity values ensuring, the success of the process.


Assuntos
Chlorella vulgaris , Microalgas , Anaerobiose , Reatores Biológicos , Nitrogênio , Fósforo , Eliminação de Resíduos Líquidos , Águas Residuárias
11.
Sci Total Environ ; 702: 134995, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31710849

RESUMO

Flocculants are foreign particles that aggregate suspended microalgae cells and due to cost factor and toxicity, harvesting of microalgae biomass has shifted towards the use of bioflocculants. In this study, mild acid-extracted bioflocculants from waste chicken's eggshell and clam shell were used to harvest Chlorella vulgaris that was cultivated using chicken compost as nutrient source. It was found that a maximum of 99% flocculation efficiency can be attained at pH medium of 9.8 using 60 mg/L of hydrochloric acid-extracted chicken's eggshell bioflocculant at 50 °C of reaction temperature. On the other hand, 80 mg/L of hydrochloric acid-extracted clam shell bioflocculant was sufficient to recover C. vulgaris biomass at pH 9.8 and optimum temperature of 40 °C. The bioflocculants and bioflocs were characterized using microscopic, zeta potential, XRD, AAS and FT-IR analysis. The result revealed that calcium ions in the bioflocculants are the main contributor towards the flocculation of C. vulgaris, employing charge neutralization and sweeping as possible flocculation mechanisms. The kinetic parameters were best fitted pseudo-second order which resulted in R2 of 0.99 under optimal flocculation temperature. The results herein, disclosed the applicability of shell waste-derived bioflocculants for up-scaled microalgae harvesting for biodiesel production.


Assuntos
Biocombustíveis , Chlorella vulgaris/fisiologia , Floculação , Aquicultura , Biomassa , Íons , Cinética , Microalgas , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura Ambiente
12.
Bioresour Technol ; 299: 122636, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31881438

RESUMO

Catalytic and non-catalytic co-pyrolysis behaviors, kinetics and products distribution of rural solid waste (RSW) and chlorella vulgaris (CV) were studied by thermogravimetric analysis (TGA) and fixed bed reactor. TGA results showed that co-pyrolysis of RSW and CV presented synergism by decreasing the temperature relating to the first mass loss peak. All the additives reduced residual mass for co-pyrolysis (5.21%, 1.57% and 4.89% for CaO, MgO and HZSM-5). Addition of CaO increased activation energy while HZSM-5 and MgO reduced it. Co-pyrolysis of RSW and CV remarkably reduced carboxylic acids and nitrogenous compounds especially for 1:1 ratio. (30.85% and 25.87%). Catalytic pyrolysis with CaO showed the best results by increasing aliphatic hydrocarbons especially light fraction (5.96%-11.98%), reducing acids (0%-30.85%) and nitrogenous compounds (0.08%-17.26%), causing higher HHV of oil. Overall, catalytic co-pyrolysis of CV and RSW with CaO could obtain bio-oil of higher quality.


Assuntos
Chlorella vulgaris , Biocombustíveis , Catálise , Temperatura Alta , Cinética , Pirólise , Resíduos Sólidos
13.
Chemosphere ; 238: 124576, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31421462

RESUMO

This study assesses and compares the influence of silver nanoparticles (AgNPs) and silver nitrate (AgNO3) on the fatty acid composition, pigments, and growth indices of Chlorella vulgaris. Toxicity testing was carried at the estimated and/or above predicted environmental concentrations of AgNPs and AgNO3. AgNO3 treatments impaired the population growth of C. vulgaris about 2-183 times more than the respective AgNPs ones. The pigments displayed a concentration-dependent decrease in response to both forms of silver; however, AgNO3 displayed higher severity to the pigments than AgNPs. In exposure to 10 µg L-1 AgNO3, the contents of chlorophyll a, chlorophyll b, total chlorophyll, and carotenoid, respectively, demonstrated a reduction of about 5, 3, 4, and 4 times when compared with the same respective concentration of AgNPs. Total amounts of saturated (∑SFA), monounsaturated (∑MUFA), and polyunsaturated (∑PUFA) fatty acids as well as the ratio of unsaturated to saturated ones (Unsat./Sat.) displayed somewhat similar-concentration responses. ∑SFA exhibited a hormesis response, and ∑MUFA, ∑PUFA, and Unsat./Sat. did a decreasing trend with increasing concentration of AgNPs and AgNO3. Myristoleic acid, nervonic acid, and eicosadienoic acid revealed the highest sensitivity. Pearson analysis illustrated the highest correlation among myristoleic acid, eicosenoic acid, and nervonic acid as well as among palmitic acid, stearic acid, palmitoleic acid, and oleic acid. Taken together, AgNPs and the released ions could disrupt physiological health state of microalgae through perturbation in the fatty acid composition (especially MUFAs and PUFAs) and other macromolecules. These types of bioperturbations could change the good health state of aquatic ecosystems.


Assuntos
Chlorella vulgaris/crescimento & desenvolvimento , Poluentes Ambientais/toxicidade , Ácidos Graxos/metabolismo , Nanopartículas Metálicas/toxicidade , Nitrato de Prata/toxicidade , Prata/toxicidade , Carotenoides/metabolismo , Chlorella vulgaris/metabolismo , Clorofila/metabolismo , Clorofila A/metabolismo , Ecossistema , Ecotoxicologia , Ácidos Graxos Monoinsaturados/metabolismo , Microalgas/efeitos dos fármacos , Testes de Toxicidade
14.
Bioresour Technol ; 295: 122251, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31630002

RESUMO

Two TaqMan® qPCR assays were developed to specifically quantify the absolute abundance of Scenedesmus obliquus and Chlorella vulgaris in mixed-species algal biofilms by targeting the psbA gene. Standard curves were developed with amplification efficiencies of 92.4% and 96.6% for S. obliquus and C. vulgaris, respectively, and an R2 value of 0.99 for both. Calibration curves for estimating absolute cell abundances resulted in slopes of 0.98 and 1.11 for C. vulgaris and S. obliquus, respectively, and an R2 value of 0.95 for both. The assays were applied to cultivated mixed-species biofilms and approximately 107 cells of each algal species were quantified when 107 cells were added into biofilms. The developed qPCR assays were concluded to be specific and accurate for the quantification of S. obliquus and C. vulgaris in mixed-species biofilms. This will contribute to the control and optimization of algal cultivation systems for the production of algal biofuels and bioproducts.


Assuntos
Chlorella vulgaris , Microalgas , Scenedesmus , Biofilmes , Biocombustíveis , Biomassa , Clorofíceas
15.
Aquat Toxicol ; 217: 105317, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31670168

RESUMO

The microalga Chlorella vulgaris is one of the prominent and most widely distributed green microalgae found in aquatic environments, often used in toxicity tests due to its sensitivity to various pollutants. To examine the toxicity of metals found in the effluent discharges from an electroplating industry, physicochemical parameters in the microalga C. vulgaris were measured. pH, turbidity, total dissolved solids, color, and the concentrations of metals such as chromium (1.97 mg/L), mercury (104.2 mg/L), and zinc (167.25 mg/L) were found exceeding the permissible limits. Several endpoints such as total protein content, reactive oxygen species (ROS) production, photosynthetic pigment contents, and antioxidant enzymatic activities, including those of superoxide dismutase (SOD) and catalase (CAT), were measured in C. vulgaris in response to treated electroplating industrial effluent (TEPIE). In addition, concentration-dependent morphological changes were also observed in response to TEPIE. Under both acute and chronic TEPIE exposure, increase in the ROS level was observed indicating increased production of ROS in C. vulgaris cells. The total protein and chlorophyll contents were found to be gradually decreasing in an effluent concentration-dependent manner. Moreover, lower concentrations of effluent stimulated the antioxidant enzyme systems. A concentration-dependent increase was observed in both SOD and CAT enzymatic activities. The results indicated toxic impairments by the effluent on the function of C. vulgaris in response to both acute and chronic exposure, indicating an urgent need of proper treatment processes/modification of the existing one of TEPIE, with continuous monitoring of the discharge of the pollutants into the aquatic ecosystems using biological assays.


Assuntos
Antioxidantes/metabolismo , Chlorella vulgaris/metabolismo , Galvanoplastia , Resíduos Industriais , Metais/toxicidade , Microalgas/metabolismo , Poluentes Químicos da Água/toxicidade , Proteínas de Algas/metabolismo , Catalase/metabolismo , Chlorella vulgaris/efeitos dos fármacos , Chlorella vulgaris/ultraestrutura , Clorofila/metabolismo , Microalgas/efeitos dos fármacos , Microalgas/ultraestrutura , Fotossíntese/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Superóxido Dismutase/metabolismo , Testes de Toxicidade
16.
Environ Sci Technol ; 53(23): 13938-13948, 2019 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-31671268

RESUMO

Single-layer molybdenum disulfide (SLMoS2) are applied as a hot 2D nanosheet in various fields involving water treatments. Both intentional design and environmental or biological processes induce many nanoholes in SLMoS2. However, the effects of nanoholes on the environmental stability and ecotoxicity of SLMoS2 remain largely unknown. The present work discovered that visible-light irradiation induced nanoholes (diameters, approximately 20 nm) in the plane of SLMoS2, with irregular edges and increased interplanar crystal spacing. The ratios of Mo to S in pristine and transformed SLMoS2 were 0.53 and 0.33, respectively. After 96 h exposure at concentrations from 0.1 to 1 mg/L, the above nanoholes promoted algal division, induced a stress-response hormesis, decreased the generation of •OH, and mitigated the cell shrinkage and wall rupture of Chlorella vulgaris induced by SLMoS2. In terms of stress response, the nanohole-bearing SLMoS2 induced fewer vacuoles and polyphosphate bodies of Chlorella vulgaris than the pristine form. Metabolomic analysis revealed that nanoholes perturbed the metabolisms of energy, carbohydrates, and fatty acids. This work proposes that nanoholes cause obvious effects on the environmental fate and ecotoxicity of SLMoS2 and that the environmental risks of engineered nanomaterials should be reevaluated using nanohole-bearing rather than pristine forms for testing.


Assuntos
Chlorella vulgaris , Nanoestruturas , Dissulfetos , Molibdênio
17.
Environ Sci Pollut Res Int ; 26(36): 36380-36387, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31713820

RESUMO

Green algae are dominant primary producers in aquatic environments. Thus, assessing the influences of pollutants such as nanoparticles on the algae is of high ecological significance. In the current study, cadmium selenide nanoparticles (CdSe NPs) were synthesized using the hydrothermal method and their characteristics were determined by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FT-IR) techniques. Subsequently, the toxicity of synthesized nanoparticles on the green microalga Chlorella vulgaris was investigated. The observations by SEM confirmed that exposure to CdSe NPs had severe impacts on the algal morphology. Furthermore, the obtained results revealed the toxic effect of CdSe NPs by a decrease in the number of cells. Measurement of antioxidant enzymes activity showed an increase in the activity of catalase, and a decrease in the activity of superoxide dismutase (SOD) at high concentrations of CdSe NPs. The exposure of C. vulgaris to CdSe NPs resulted also in a change in algal pigments as well as total phenol content. Taken together, CdSe NPs appeared to have significant cytotoxic effects on C. vulgaris in the applied concentrations.


Assuntos
Antioxidantes/metabolismo , Compostos de Cádmio/toxicidade , Chlorella vulgaris/efeitos dos fármacos , Nanopartículas/toxicidade , Compostos de Selênio/toxicidade , Compostos de Cádmio/química , Catalase/metabolismo , Chlorella vulgaris/enzimologia , Chlorella vulgaris/crescimento & desenvolvimento , Nanopartículas/química , Tamanho da Partícula , Compostos de Selênio/química , Superóxido Dismutase/metabolismo , Propriedades de Superfície
18.
Environ Sci Pollut Res Int ; 26(36): 36985-36992, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31745799

RESUMO

In this study, the growth and high-valued products accumulation characteristics of three common high-valued microalgae (Chlorella sp. HQ, Scenedesmus sp. LX1, and Chlorella vulgaris) in saline-alkali leachate were compared to select the species with greatest utilization potential. The results showed that after 28 days of cultivation, among three microalgae, Chlorella sp. HQ grew best with its maximum density at peak of 1.16 × 107 cells mL-1 and lipid production per unit cell (0.047 ± 0.006 × 10-7 mg cell-1) and lipid content (18.18 ± 3.14%) were largest. The triacylglycerol (TAG) yield and content of Scenedesmus sp. LX1 were the highest, reaching 0.005 ± 0.000 × 10-7 mg cell-1 and 19.74 ± 2.53%, respectively, which was slightly higher than those of Chlorella sp. HQ. According to comprehensive comparison, Chlorella sp. HQ was most suitable to grow in the saline-alkali leachate in terms of algal density, lipid yield, and content. The potential comparison and effects of salinity on the high-valued products accumulation of Chlorella sp. HQ compared with those in SE standard medium, reclaimed water, and tap water were further carried out. It was found that the density order of Chlorella was saline-alkali leachate > SE medium > reclaimed water > tap water. And the Chlorella density in the leachate with a salinity of 0.14% was greater than the other three salinities (0.32%, 0.45%, and 0.6%) at the end of cultivation. While the maximum lipid yield per unit cell and lipid content of Chlorella occurred in the salinity of 0.6%, which indicated that high salinity promoted the accumulation of lipid. Furthermore, other high-valued products (including starch, protein, total sugar, and photosynthetic pigments) accumulation characteristics were analyzed and found that they were all superior than those in SE medium. And with the salinity decreased, the microalgal protein and starch contents decreased. The contents of photosynthetic pigment and total sugar reached a maximum at salinities of 0.32% and 0.45%, respectively.


Assuntos
Microalgas/fisiologia , Poluentes da Água/análise , Álcalis , Biocombustíveis , Biomassa , China , Chlorella vulgaris , Lipídeos , Microalgas/crescimento & desenvolvimento , Salinidade , Scenedesmus/metabolismo , Triglicerídeos , Águas Residuárias , Água/metabolismo
19.
Environ Monit Assess ; 191(11): 679, 2019 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-31655913

RESUMO

Algal treatment methods have been widely used in nutrient removal studies. However, in most cases, the experimental conditions have not been fully complied with actual conditions. For instance, the effect of algae acclimation to wastewater medium on cell growth and removal efficiency has generally been ignored in laboratory scale experiments. This paper investigates the effect of acclimation on cell growth and nutrient uptake rates of Arthrospira platensis and Chlorella vulgaris. For this purpose, batch reactors, which contained the synthetic secondary effluent, had been inoculated by acclimated algae cells and the growth parameters were measured daily, as well as nutrient concentration. A significant decrease (P < 0.05) in chlorophyll-a content of acclimated A. platensis was observed, although there was no significant change in specific growth rate (µ) and doubling time (dt), in comparison with the non-acclimated ones. Moreover, the acclimation process changed the chlorophyll-a content and kinetic parameters of Chlorella vulgaris. Furthermore, t test results showed a significant increase in removal rate of nitrogen compounds through the acclimation. Residence time of A. platensis and C. vulgaris was also reduced through the acclimation by approximately 50% and 25%, respectively.


Assuntos
Chlorella vulgaris/fisiologia , Eliminação de Resíduos Líquidos/métodos , Aclimatação , Chlorella vulgaris/crescimento & desenvolvimento , Clorofila/análogos & derivados , Monitoramento Ambiental , Cinética , Nitrogênio/análise , Nutrientes , Fósforo/análise , Spirulina/fisiologia , Águas Residuárias
20.
Aquat Toxicol ; 216: 105319, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31586885

RESUMO

Microplastics (MPs) could pose potential risks to microalgae, the primary producer of marine ecosystems. Currently, few studies focus on the interaction of aged MPs with other pollutants and their toxic effects to microalgae. Therefore, the present study aimed to investigate i) the aging of microplastics polyvinyl chloride (mPVC) in simulated seawater and the changes in physical and chemical properties; ii) the effects of single mPVC (virgin and aged) and copper on microalgae Chlorella vulgaris; and iii) the interaction of aged mPVC and copper and the oxidative stress towards C. vulgaris. In this study, some wrinkles, rough and fractured surface textures can be observed on the aged mPVC, accompanying with increased hydroxyl groups and aromatic carbon-carbon double bond but decreased carbon hydrogen bond. It was found that single virgin or aged mPVC at low concentration (10 mg/L) had significant inhibition on the growth of C. vulgaris but no inhibition at higher concentration (100, 1,000 mg/L), which can be reasonably explained by the aggregation and precipitation of mPVC at high concentration. The aging of mPVC inhibited the growth of C. vulgaris with the maximum growth inhibition ratio (IR) of 35.26% as compared with that of virgin mPVC (IR = 28.5%). However, the single copper could significantly inhibit the growth of C. vulgaris and the inhibitory effects increased with concentration (0.2, 0.5, 1.0 mg/L). Furthermore, both the single aged mPVC (10 mg/L) and copper (0.5 mg/L) caused serious cell damage, although the concentration of superoxide dismutase (SOD) and the intracellular malonaldehyde (MDA) increased. In contrast to single treatment, the growth of C. vulgaris can be enhanced by the combined group with copper (0.5 mg/L) and aged mPVC (10 mg/L).


Assuntos
Chlorella vulgaris/efeitos dos fármacos , Cobre/toxicidade , Microalgas/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Cloreto de Polivinila/toxicidade , Antioxidantes/metabolismo , Biomassa , Proliferação de Células/efeitos dos fármacos , Chlorella vulgaris/citologia , Chlorella vulgaris/enzimologia , Chlorella vulgaris/ultraestrutura , Malondialdeído/metabolismo , Microalgas/citologia , Microalgas/enzimologia , Microalgas/ultraestrutura , Tamanho da Partícula , Água do Mar/química , Superóxido Dismutase/metabolismo , Raios Ultravioleta , Poluentes Químicos da Água/toxicidade
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