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1.
Bioresour Technol ; 313: 123743, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32620368

RESUMO

Nitrite removal is necessary and significant for pickle and meat processing wastewater. In this study, Chlorella sp. L38 is used as an alternative to remove nitrite and reuse it as nitrogen source for potential value-added ingredients production. Based on the typical BG11 medium with and without NaNO3 (which is the conventional nitrogen source), nitrite is additionally provided, and its concentration gradient was set at 0, 50, 100, 150 and 200 µmol/L, respectively. The experimental results showed that the nitrite removal rate could achieve 57.1 µmol/L/d. In addition, the biomass variation, and value-added ingredients (polysaccharides, lipid, and protein) productivity were also measured, and their yield could achieve 4.8 mg/g/d, 3.0 mg/L/d and 5.5 mg/L/d, respectively. It indicated that Chlorella sp. L38 has the potential to be an environmentally friendly approach for nitrite removal of wastewater.


Assuntos
Chlorella , Microalgas , Biomassa , Nitritos , Nitrogênio , Águas Residuárias
2.
Bioresour Technol ; 313: 123506, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32512426

RESUMO

Here the study designed a pH-stat culture medium that named as Glucose-Acetate-Phosphorus (GAP) for the mixotrophic cultivation of Chlorella for biomass production. With no addition of pH buffer, the culture pH during mixotrophic growth was effectively maintained steady between 7.5 and 8.5 by balancing the ammonium, acetate and glucose uptakes. Based on the GAP medium supplying with 2 g·L-1 of total organic carbon, the biomass productions of four Chlorella species were determined as 4.08-4.56 g·L-1. In contrast to the cultivation using medium Tris-Acetate-Phosphorus (TAP), a algal culture medium that usually regarded as specific for mixotrophy, the cultivation in GAP were about 1.79-1.86 times higher in biomass production and 83.9-88.9% lower in production cost. The developed GAP medium is a promising alternative for the mixotrophic cultivation of microalgae to produce biomass and cellular contents.


Assuntos
Chlorella , Microalgas , Acetatos , Biomassa , Glucose , Concentração de Íons de Hidrogênio , Fósforo
3.
Bioresour Technol ; 313: 123499, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32554150

RESUMO

To achieve a high consumption rate of ammonium with biomass coproduction, the mixotroph Chlorella pyrenoidosa was cultivated in high ammonium-high salinity wastewater medium in this study. The initial cell density, glucose and ammonium concentrations, and light intensity were optimized in shake flasks. A 5-L fermenter with surrounding LED (Light Emitting Diode) and a 50-L fermenter with inlet LED were employed for batch and semicontinuous cultivation. The results demonstrated that the highest contents of protein (56.7% DW) and total pigments (4.48% DW) with productivities of 5.62 g L-1 d-1 and 0.55 mg L-1 d-1, respectively, were obtained in 5-L photofermenter, while the maximum NH4+ consumption rate (1,800 mg L-1 d-1) and biomass yield (23.6 g L-1) were achieved in 50-L photofermenter. This study developed a novel strategy to convert high ammonium in wastewater to high-protein algal biomass, facilitating wastewater bioremediation and nitrogen recycling utilization by the mixotroph C. pyrenoidosa in photofermentation.


Assuntos
Compostos de Amônio , Chlorella , Microalgas , Biomassa , Reatores Biológicos , Nitrogênio , Águas Residuárias
4.
Bioresour Technol ; 313: 123624, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32593146

RESUMO

To improve Chlorella's economic viability as a natural bait in aquaculture, protoplast fusion technology was used for two Chlorella mutants, H10 and Z13, selected by UV and chemical mutagenesis. Chlorella sorokiniana protoplast was prepared using the enzyme method, and then the optimal enzyme combination of 4% cellulase and 2% driselase was screened out. Z13 and H10 protoplast preparation rates reached 34.72% and 31.11%, respectively. Nine fusions with higher growth rates were selected to assess their biomass, total and soluble proteins contents. Dry cell weight, total protein, and soluble protein of fusion R7 were 0.92 g.L-1, 67.16%, and 0.59 mg.g-1, respectively. The biomass was 1.59, 1.43 times that of H10 and Z13; total and soluble proteins increased by 8.89%, 10.25% and 50.12%, 74.62% respectively, compared with the original algae. These results have implications for breeding excellent strains, and for large-scale and optimal application of Chlorella in aquaculture.


Assuntos
Chlorella , Aquicultura , Biomassa , Cruzamento , Protoplastos
5.
Sci Total Environ ; 729: 138666, 2020 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-32498154

RESUMO

Cyanobacteria and microalgae are abundant biota groups in eutrophic freshwater ecosystems, serving as a food source for many aquatic organisms, including the larvae of non-biting midges (Chironomidae). Many species of cyanobacteria are toxin producers, which can act as stressors to other organisms. The present study aimed to analyze and compare the effects of dietary exposure to the common toxic cyanobacteria Anabaena sp. and non-toxic microalgae Chlorella sp. in Chironomus riparius larvae. Microcystin was detected and quantified in the methanolic extract of Anabaena sp. using the HPLC-DAD technique, and it was identified as microcystin-LR. Both Anabaena sp. and Chlorella sp. were suitable food sources to enable the survival of C. riparius larvae in laboratory conditions, causing negligible mortality and significant differences in the larval mass (ANOVA and Post hoc LSD test; p < 0.05) and hemoglobin concentration (Student's t-test; p < 0.05). Oxidative stress parameters such as advanced oxidation protein products (AOPP), thiobarbituric acid reactive substances (TBARS), catalase (CAT) and superoxide dismutase (SOD) activity, and DNA damage, were also investigated. One-way ANOVA, followed by the Post hoc LSD test, showed a significant increase in AOPP and CAT for the group of larvae fed with Chlorella sp. The same test showed moderate DNA damage in both groups of larvae, with greater damage in the group fed with Anabaena sp. Thus, Chlorella sp. and microcystin-LR producing Anabaena sp. are food sources that did not result in any drastic acute effect on the population level of C. riparius larvae. However, sub-individual-level endpoints revealed significant effects of the treatments, since they caused oxidative stress and DNA damage that may pose a danger to successive generations of test organisms.


Assuntos
Anabaena , Chironomidae , Chlorella , Animais , Ecossistema , Larva , Fitoplâncton , Poluentes Químicos da Água
6.
J Environ Manage ; 268: 110693, 2020 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-32510435

RESUMO

The demand for systems that efficiently and sustainably recover value-added compounds and materials from waste streams is a major challenge. The use of wastewater as a source for recovery of carbon and nutrients is an attractive and sustainable alternative. In this study, anaerobically treated black water was treated in photobioreactors (PBRs) inoculated with Chlorella sorokiniana, and the process was investigated in terms of phosphorus and nitrogen removal, biomass growth, and the removal of pathogens. The consumption of bicarbonate (alkalinity) and acetate (volatile fatty acids) as carbon sources by microalgae was investigated. The average nutrient removal achieved was 66% for N and 74% for P. A high consumption of alkalinity (83%) and volatile organic acids (76%) was observed, which suggests that these compounds were used as a source of carbon. The biomass production was 73 mg L-1 day-1, with a mean biomass of 0.7 g L-1 at the end of the batch treatment. At the end of the experiments, a log removal/inactivation of 0.51 log for total coliforms and 2.73 log for Escherichia coli (E. coli) was observed. The configuration used, a flat-panel PBR operated in batch mode without CO2 supplementation, is a cost-effective and environmentally sustainable method for recovering of nutrients and production of algal biomass.


Assuntos
Chlorella , Microalgas , Biomassa , Escherichia coli , Nitrogênio , Nutrientes , Fósforo , Fotobiorreatores , Águas Residuárias , Água
7.
Sheng Wu Gong Cheng Xue Bao ; 36(6): 1150-1161, 2020 Jun 25.
Artigo em Chinês | MEDLINE | ID: mdl-32597064

RESUMO

The aim of this study was to establish a novel technology using microalgae for NO3⁻ removal from high concentration wastewater and conversion to algal proteins. The effects of cultivation modes and illumination modes on the biomass yield, NO3⁻ assimilation rate and algal protein yield were first investigated in shaking flasks for mixotrophic cultivation of Chlorella pyrenoidosa, and subsequently the scale-up verification in 5-L photo fermenter was successfully conducted. Fed-batch cultivation without medium recycling was the best cultivation mode in shaking flask system, in which the highest biomass yield (35.95 g/L), the average NO3⁻ assimilation rate (2.06 g/(L·d)) and algal protein content (up to 42.44% of dry weight) were achieved. By using a staged increase of light intensity as illumination modes, the specific growth rate of cells could be significantly promoted to the highest (0.65 d⁻¹). After a 128-hour continuous cultivation in a 5-L photo fermenter, the highest biomass yield and the average NO3⁻ assimilation rate were reached to 66.22 g/L and 4.38 g/(L·d) respectively, with the highest algal protein content at 47.13% of dry weight. Our study could provide a photo fermentation technology of microalgae for highly efficient treatment of waste industrial nitric acid and/or high concentration nitrate wastewater. This microalgae-based bioconversion process could coproduce protein-rich microalgal biomass, which facilitates the resource utilization of these type wastewater by trash-to-treasure conversion.


Assuntos
Proteínas de Algas , Chlorella , Nitratos , Nitrogênio , Purificação da Água , Proteínas de Algas/biossíntese , Biomassa , Nitratos/isolamento & purificação , Nitratos/metabolismo , Nitrogênio/metabolismo , Águas Residuárias/química , Purificação da Água/métodos
8.
Sci Total Environ ; 733: 139348, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32446083

RESUMO

Roxithromycin (ROX) is a widely used macrolide antibiotic and its environmental fate and ecotoxicity have attracted considerable attention. In this study, the phototransformation kinetics and products of ROX under the irradiation of simulated sunlight were investigated. The ecotoxicity of ROX before and after phototransformation were also examined using the bioluminescence bioassay and algae growth inhibition test. The results showed that ROX underwent direct photolysis and indirect photolysis in the presence of Suwannee River humic acid (SRHA) and Suwannee River natural organic matter (SRNOM). The kinetic rate constant of the photodegradation of ROX in the presence of 20 mg·L-1 SRHA and SRNOM were 4.0 and 3.6 times higher than direct photolysis in the absence of dissolved organic matter (DOM). A total of 20 phototransformation products (PTPs) formed as a result of the photodegradation of ROX by simulated solar irradiation were identified, and 10 of them were reported for the first time. The PTPs were generally formed through the N-demethylation, O-demethylation or direct cleavage of the side chain, desosamine or cladinose moiety from ROX. Solutions containing ROX and its PTPs showed an increased toxicity to Vibrio fischeri, demonstrating some PTPs were more toxic to V. fischeri. On the other hand, the toxicity of ROX after irradiation to Chlorella pyrenoidosa decreased, suggesting the phototransformation of ROX in the environment may be a positive outcome in the context of the growth of green algae.


Assuntos
Chlorella , Roxitromicina , Poluentes Químicos da Água/análise , Cinética , Fotólise , Rios
9.
Aquat Toxicol ; 224: 105498, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32402915

RESUMO

The current study focuses on the ecotoxicity of cobalt oxide nanoparticles (Co3O4 NPs) in the aquatic environment towards freshwater microalgae, Chlorella minutissima. The interaction of Co3O4 NPs with microalgae shows the growth suppressing effect. The 72 h EC 50 (effective concentration of a chemical having 50% of its impact) values of Co3O4 NPs for C. minutissima was 38.16 ± 1.99 mg/L. The decline in chlorophyll a content and increase in reactive oxygen species (ROS) also indicated the compromised physiological state of microalgae. An increased LDH (lactate dehydrogenase) level in treated samples suggests membrane disintegration by Co3O4 NPs. Light microscopy, scanning electron microscopy (SEM) and Energy Dispersive X-Ray-Scanning electron microscopy (EDX-SEM) further confirm cell entrapment and deposition of Co3O4 NPs on the cell surface. Cellular internalization of NPs, as shown by Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES), also contributes towards the toxicity of NPs. The findings suggest the role of extracellular as well as intracellular nanoparticles (NPs) in exerting a toxic effect on the C. minutissima.


Assuntos
Chlorella/efeitos dos fármacos , Cobalto/toxicidade , Água Doce/química , Nanopartículas Metálicas/toxicidade , Microalgas/efeitos dos fármacos , Óxidos/toxicidade , Poluentes Químicos da Água/toxicidade , Chlorella/metabolismo , Clorofila A/metabolismo , Cobalto/metabolismo , Microalgas/metabolismo , Microscopia Eletrônica de Varredura , Óxidos/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Poluentes Químicos da Água/metabolismo
10.
Bioresour Technol ; 310: 123472, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32388205

RESUMO

The aim of this work was to propose a novel process to make Chlorella pyrolyzed and in situ upgraded to fuel over amphiphilic SO3H-SBA-15 catalysts. This strategy is developed to build a Pickering emulsion system through the w/o (water/decalin) droplets. Chlorella catalytic pyrolysis has been conducted under the different heating rates to get the activation energy 166 kJ/mol (α = 0.5) according to the kinetic-free model. Palmitic acid, as a model compound, was employed for TG and DRIFTS analysis to elucidate the pyrolysis and deoxygenation reaction pathway. n-hexadecane pyrolysis at 3 MPa N2 illustrated the peak cracking temperature declining from thermally 422 °C to catalytically 413 °C. N2 physisorption of the fresh and post-reaction catalysts indicated that there is little catalyst decay. With improved thermal stability and hydrophobicity, the SO3H-SBA-15 catalysts showed enhanced performance for Chlorella pyrolysis, and revealed the promising application for better fuel production in aqueous conversion.


Assuntos
Chlorella , Catálise , Cinética , Pirólise , Dióxido de Silício
11.
Water Res ; 176: 115735, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32224330

RESUMO

Graphene oxide (GO) sheets are unstable in aqueous environments, and the effect of photo-transformation on GO toxicity to freshwater algae (Chlorella pyrenoidosa) was investigated. Our results demonstrated that GO underwent photo-reduction under 25-day sunlight irradiation, and the transformation was generally completed at Day 8. The toxicological investigation showed that 8-day sunlight irradiation significantly increased growth inhibition of GO (25 mg/L) to algal cells by 11.2%, due to enhanced oxidative stress and stronger membrane damage. Low molecular weight (LMW) species were produced during the 8-day GO transformation, and they were identified as two types of aromatic compounds, which played a crucial role in increasing toxicity. The combined toxicity of GO and Cu2+ ions before and after light irradiation was further investigated. Antagonistic effect was observed between the toxicity of pristine GO and co-existing Cu2+ ions. After co-irradiation of GO and Cu2+ ions for 8 days, their combined toxicity was unexpectedly lower or insignificant in comparison with the treatments of pristine GO, or pristine GO in the presence of Cu2+ ions. Two mechanisms were revealed for this finding: (1) Cu2+ ions suppressed the photo-transformation of GO; (2) the toxicity of free Cu2+ ions was decreased through the adsorption/retention of Cu2+ ions and formation of Cu-based nanoparticles (e.g., Cu2O and Cu2S) on the photo-transformed GO. The provided data are helpful for better understanding the environmental process and risk of GO under natural conditions.


Assuntos
Chlorella , Grafite , Poluentes Químicos da Água , Água Doce , Íons , Metais
12.
Ecotoxicol Environ Saf ; 197: 110573, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32278825

RESUMO

Antibiotics had been paid more and more attention to their toxicity to non-target aquatic organisms in the aquatic environment. As azithromycin (AZI) was an important antibiotic pollutant in water, its toxicity to aquatic organisms had been investigated. In this study, the potential aquatic ecological risk of AZI was identified by assessing the toxicity on the feeding behavior and physiological function of Daphnia magna (D. magna) under the different exposure pathways (aqueous phase exposure vs. food phase exposure). For the food Chlorella pyrenoidosa (C. pyrenoidosa), AZI could inhibit the growth and nutrition accumulation with concentration- and time-response relationship. For D. magna, the feeding behavior was inhibited by AZI under the aqueous phase exposure pathway. However, the feeding behavior was inhibited firstly and then reversed into promotion in the low and medium concentration groups and was continually promoted in the high concentration group under the food phase exposure pathway. The accumulation of polysaccharides and total protein were decreased in D. magna n the high concentration group under the aqueous phase exposure pathway, while the accumulation of polysaccharides and crude fat were decreased in the high concentration group under the food phase exposure pathway. The activity of amylase (AMS) and trypsin in D. magna were decreased after exposure to AZI under the aqueous phase exposure pathway. On the other hand, the activity of AMS in the medium and high concentration groups was decreased under the food phase exposure pathway, but the activity of trypsin was decreased in the medium concentration group and increased in the high concentration group. The levels of ROS in D. magna were also measured and increased in both exposure pathways except in the low concentration group under the food phase exposure pathway, indicating the oxidative stress injury of D. magna. Our results showed that AZI could affect the digestive enzyme activities and oxidative stress-antioxidative system, ultimately leading to the change of D. magna's feeding behavior and nutrition accumulation. These results also provided a comprehensive perspective to evaluate the toxic effects of non-lethal dose antibiotics to non-target aquatic organisms via different exposure pathways.


Assuntos
Azitromicina/toxicidade , Daphnia/efeitos dos fármacos , Comportamento Alimentar/efeitos dos fármacos , Nutrientes/metabolismo , Poluentes Químicos da Água/toxicidade , Animais , Azitromicina/metabolismo , Chlorella/metabolismo , Daphnia/metabolismo , Daphnia/fisiologia , Exposição Dietética/efeitos adversos , Exposição Ambiental/efeitos adversos , Estresse Oxidativo/efeitos dos fármacos , Poluentes Químicos da Água/metabolismo
13.
Environ Sci Pollut Res Int ; 27(19): 23963-23980, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32304062

RESUMO

In this study, a novel two-step integrated process is proposed to facilitate the microalgae biofuel production as well as fresh cheese whey wastewater (FCWW) treatment simultaneously. The pre- and post-treatment of high-strength FCWW were performed by means of coagulation and algal cultivation, respectively. The pre-treatment of FCWW for maximum removal of chemical oxygen demand (COD), turbidity (TUR) and total solids (TS) as responses was obtained by statistical optimization of coagulation parameters. The maximum removal of COD, TUR and TS at the optimum level of variables was obtained as 68.09%, 47.80% and 73.63%, respectively. The pre-treated FCWW was further treated by Chlorella pyrenoidosa and observed a significant reduction in the above-mentioned responses (87-94%). The maximum algal biomass yield and lipid productivity were observed as 2.44 g L-1 and 77.41 mg L-1 day-1, respectively. Based on promising results of FCWW treatment and its use as a third-generation biodiesel feedstock, a cost-benefit analysis of the developed process was assessed for microalgal oil production. The total profit earned by the integrated process model was $9.59 million year-1. Accordingly, the estimated production cost of algal oil (TAG) from the developed system was estimated to be $79.03 per barrel.


Assuntos
Queijo , Chlorella , Microalgas , Biocombustíveis , Biomassa , Análise Custo-Benefício , Nitrogênio/análise , Águas Residuárias , Soro do Leite/química
14.
Environ Pollut ; 263(Pt B): 114593, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32315820

RESUMO

Plastic pollution has become a pressing issue due to its persistence in the environment. Smaller plastics are more easily ingested, potentially exerting greater influences on organisms. In this study, the effects of polystyrene nanoplastics (NP) on the toxic effects, bioaccumulation, biodegradation and enantioselectivity of ibuprofen (IBU) in algae Chlorella pyrenoidosa were explored. The influences on the growth rate, chlorophyll a, total antioxidant capacity (T-AOC), reactive oxygen species (ROS) and lipid peroxidation (MDA) were evaluated after 96 h of exposure to a combination of polystryene NP (1 mg L-1) and IBU (5-100 mg L-1). The results indicated that the inhibitory effect of IBU on C. pyrenoidosa growth was alleviated in the presence of NP. For instance, the 96 h-IC50 value for rac-IBU in the treatment lacking NP was 45.7 mg L-1, and the corresponding value in the treatment containing NP was 63.9 mg L-1. The co-exposure of NP led to a significant enhancement of T-AOC and slight reduction of ROS and MDA compared with the individual exposure (IBU) group, suggesting a decreased oxidative stress. In addition, treatment with NP led to a decreased bioaccumulation and accelerated biodegradation of IBU in C. pyrenoidosa and enhanced removal in the medium. The enantioselective toxicity, bioaccumulation and biodegradation of IBU were observed both in the absence and presence of NP. S-IBU exhibited a greater toxicity, and R-IBU was preferentially accumulated and degraded in C. pyrenoidosa. No interconversion of the two enantiomers occurred regardless of the presence of NP. This consequence implied that the influence of coexistent NP should be considered in the environmental risk assessment of pharmaceuticals and personal care products in aquatic environments.


Assuntos
Chlorella , Poluentes Químicos da Água/análise , Bioacumulação , Clorofila A , Água Doce , Ibuprofeno
15.
Sci Total Environ ; 727: 138616, 2020 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-32325314

RESUMO

The effluent from municipal wastewater can be discharged into the surface water once the chemical parameters meet the standard requirements. However, little attention has been paid to assess the toxicity of the effluent in the receiving water. In this study, vertical flow constructed wetlands (VFCWs) were used to treat the heavy metal-containing wastewater. In addition, the toxicity of the effluent towards Chlorella pyrenoidosa and Daphnia magna was evaluated. The results showed that the VFCWs removed nearly 80% of the total nitrogen, nitrate, and Cd2+ from the wastewater during a 60 day operation. Acute toxicity assessments demonstrated that incubating the plankton in 10% (v/v) effluent enhanced their growth, but a further increase in the effluent proportion (50% and 100%) exhibited detrimental effects towards the aquatic organisms. The superoxide dismutase (SOD) and peroxidase (POD) activities in C. pyrenoidosa and D. magna peaked but then decreased with the increasing effluent proportion, indicating that incubation in a higher proportion of the effluent could damage the anti-oxidative capabilities of the organisms, which aligned with the enhanced reactive oxygen species (ROS) levels and malondialdehyde (MDA) contents. After 96 h of incubation, the assimilation of Cd2+ was most obvious in all the studied effluent gradients in comparison to Cu2+ and Pb2+. Additionally, the correlation analysis between the plankton growth and heavy metal removal revealed that Cd2+ removal clearly benefited the growth of C. pyrenoidosa and D. magna. These results suggest that additional endeavor should be made on the heavy metal removal, to reduce the potential ecological risk of the final discharge.


Assuntos
Chlorella , Metais Pesados , Poluentes Químicos da Água/análise , Animais , Eliminação de Resíduos Líquidos , Águas Residuárias/análise , Áreas Alagadas
16.
Bioresour Technol ; 310: 123403, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32339891

RESUMO

The reduction of resource requirements for the outdoor cultivation of Chlorella sorokiniana using 180 L flat panel photobioreactors through medium recycling was investigated in this study. Without medium recycling, algae grew in 13.6 d from 0.92 to 5.32 gL-1with a productivity of 0.32 gL-1d-1. For the production of 748 g algae dry weight (DW), 152gkg-1 N, 27 gkg-1 P and 231 Lkg-1 water were needed. A realistic cultivation model with the recycling of medium and a productivity of 0.4 gL-1d-1 was set up based on experimental data, in which the requirements decreased to 104gkg-1 N, 24 gkg-1 P and 141 Lkg-1 water. Compared to the production of lutein-containing plant Tagetes erecta, water and potassium requirements of up to 91% less and 96% respectively and higher biomass productivity by the factor 3.7 was achieved.


Assuntos
Chlorella , Microalgas , Biomassa , Fotobiorreatores , Reciclagem
17.
Bioresour Technol ; 309: 123380, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32325378

RESUMO

Contamination of freshwater raceway ponds impedes the commercial cultivation of microalgae. Acclimatization of freshwater microalgae to hypersaline conditions offers a means to reduce contamination. A freshwater Chlorella species was cultured in a gradient of salinities ranging from 5 to 40‰ and pulse amplitude modulated fluorometry recorded photosynthetic functioning. While the average salinity of seawater is 35‰, optimum acclimatization occurred at 20‰, at which point the growth rate (1.6 µg chl a L-1d-1) was not significantly different from the control (1.8 µg chl a L-1d-1). The maximum relative electron transfer rate was lower (9 to 12 µmol m-2s-1) at 5 to 20‰ as compared to 40‰ (28 µmol m-2s-1) where no algal growth was recorded. ATP and NADPH were thus shunted towards synthesis of molecules that offset cytoplasmic osmotic stress. Culturing this Chlorella strain in raceway ponds under saline conditions may reduce contamination and improve productivity.


Assuntos
Chlorella , Microalgas , Aclimatação , Fluorometria , Água Doce
18.
Bioresour Technol ; 307: 123233, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32240927

RESUMO

This work evaluated the potential of microalgae of Chlorella sp., SL7A, Chlorococcum sp., SL7B and Neochloris sp.,SK57 cultivated in river water contaminated with pharmaceutical effluent for biomass and lipid production. It has been observed that fast growing algae in this medium is Neochloris sp.SK57. Maximum biomass and lipid yield was obtained from Neochloris sp. SK57 (0.52 g/l) and Chlorococcum sp. SL7B (0.129 g/l)along with drycell weight of lipid was 28%.The increased in biomass and lipid in this media is could due to assimilation of organic nutrients and stress due to other components present in the river water. Fatty acid profile of algal biomass showed that saturated fatty acids production is enhanced in oils of Neochloris sp. SK57, and its suitability in food and fuel applications. Water quality of the river water was monitored before and after algal cultivation. Results showed that quality of river water was improved after algal cultivation.


Assuntos
Chlorella , Microalgas , Preparações Farmacêuticas , Biodegradação Ambiental , Biocombustíveis , Biomassa , Rios
19.
Bioresour Technol ; 307: 123253, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32244074

RESUMO

A single helical baffle (SHB), consisting of twisted turns, was developed to convert straight flow into spiral flow in a Chlorella PY-ZU1 open raceway pond (ORWP) bubbled with 15% CO2. Microalgal solution flowing through the SHB alternative helical interspaces generated whirling flow both vertically and horizontally, which decreased mixing and increased mass transfer rates. The optimized SHB had a pitch length to total SHB length ratio of 0.13 and SHB diameter to ORWP single channel width ratio of 0.30, which decreased mixing times and increased mass transfer coefficients by 41.1% and 38.4% respectively. SHB moved Chlorella PY-ZU1 from the ORWP bottom to the top, increasing light exposure for photosynthesis. Cellular electron transfer rates and photochemical efficiency (φPSII) increased by 18%, chlorophyll a content increased by 16% and variable to maximum fluorescence ratio increased by 13%. The microalgal biomass of SHB ORWP was 23% higher than that of conventional ORWP.


Assuntos
Chlorella , Microalgas , Biomassa , Dióxido de Carbono , Clorofila A
20.
Bioresour Technol ; 308: 123292, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32278995

RESUMO

In the present work Chlorella pyrenoidosa, Scenedesmus abundans and Anabaena ambigua have been evaluated for their biomass, phycoremediation efficiency and biomethane production potential by cultivating them in the primary treated sewage waste water (PTSWW) under controlled conditions. By the end of 25-day experiment, up to 52-88% reduction was observed in the nutrient concentration from the 3:1 ratio of PTSWW. Co-digestion of microalgal biomass (dry) with cow dung was performed to estimate biomethane potential. Biogas yield of 618-925 ml g-1 VS with 48-65% of methane content was obtained employing the microalgal species cultivated in PTSWW. Microalgae appeared notably competent at nutrient sequestration from PTSWW with significant microalgal biomass productivity for biogas production. Energy balance studies revealed the feasibility of coupling the remediation with energy generation. High photosynthetic rate and biomass generation ability along with nutrient confiscation supports employment of microalgae as a potential next generation biofuel source with waste management.


Assuntos
Chlorella , Microalgas , Animais , Biocombustíveis , Biomassa , Bovinos , Emprego , Estudos de Viabilidade , Feminino , Esgotos , Águas Residuárias
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