82 research outputs found
Treatment of wastewater originating from aquaculture and biomass production in laboratory algae bioreactor using different carbon sources
The aim of present study was to explore the effect of different carbon sources on biomass accumulation in microalgae Nannochloropsis oculata and Tetraselmis chuii and their ability to remove N and P compounds during their cultivation in aquaculture wastewater. Microalgae cultivation was performed in laboratory bioreactor consisted from 500 mL Erlenmeyer flasks, containing 250 mL wastewater from semi closed recirculation aquaculture system. The cultures were maintained at room temperature (25-27ºC) on a fluorescent light with a light: dark photoperiod of 15 h: 9 h. The microalgae species were cultivated in wastewater with different carbon sources: glucose, lactose and saccharose. The growth of strains was checked for 96 h period. In the present study, N. oculata and T. chuii showed better growth in wastewater from aquaculture with saccharose carbon source during the experiment. The most effective reduce of nitrate and total nitrogen was proved in N. oculata cultivated in wastewater with glucose as carbon source. T. chuii cultivated in wastewater containing glucose showed 8.27% better cleaning effect in ammonium compared with N. oculata. T. chuii grew in wastewater with glucose as carbon source showed 19.5% better removal effect in phosphate compared with N. oculata strain
Sustainable utilization of desalination concentrate
Lack of water availability is a global crisis. Many arid countries are turning to desalination technologies in order to fulfill their water needs. Hypersaline water, brine, is the byproduct of desalination and can be dangerous to the environment if disposed of in an unsustainable manner. Research surrounding brine management focuses on improved methods of direct disposal, strategies of volume minimization, and reuse strategies. However, the mentioned brine management methods revolve around chemical and mechanical techniques requiring high technological skills, know-how and energy. This thesis aims to find biological solutions that use brine, with minimum resources, in low-cost, low-energy conditions to generate economic value and to minimize the negative effects of brine by attempting to reducing brine salinity. After conducting a thorough literature review, two possible organisms, with the potential of living in brine, algae and Artemia were selected. Different algae species are able to withstand high saline environments and uptake minerals from concentrated solutions; thus decreasing its overall salinity. Artemia sp. thrives in high saline conditions producing cysts of large economic value. This thesis aims to demonstrate that Artemia can live in brine and is a viable method for revenue generation and that the algae species Nannochloropsis sp. can also be adapted to live in brine and uptake nutrients, somewhat decreasing the salinity of brine. The Artemia and algae biomass can be sold, generating additional economic benefits and minimizing the cost of such a system, thus allowing for an economically, socially and environmentally safe way to utilize desalination waste. Marine microalga Nannochloropsis sp. was tested for its salt stress tolerance and salt accumulation capability in mediums of sea salt and brine with different concentrations and nutrients. In sea salt experiments, the alga grew best in salinity 80,000 mg.l-1 with F/2 nutrients where it reached an increase of 4-fold. In brine test BH with F/2 nutrients, excluding the vitamin stock solution and substituting NaNO3 with urea, the alga was able to reach a higher growth of 5-fold. Salt accumulation was minimal and thus will not decrease the TDS of brine. Nevertheless, the optimum conditions for growth of Nannochloropsis sp. in brine were identified, the biomass may be utilized for biofuel production, to generate economic value. Artemia experiments demonstrated the organism’s ability to survive in brine. The Artemia was able to survive for two months in a medium of 100% brine, indicating that a larger brine project may be conducted using this organism to generate economic value
High-EPA Biomass from <i>Nannochloropsis salina </i>Cultivated in a Flat-Panel Photo-Bioreactor on a Process Water-Enriched Growth Medium
Nannochloropsis salina was grown on a mixture of standard growth media and pre-gasified industrial process water representing effluent from a local biogas plant. The study aimed to investigate the effects of enriched growth media and cultivation time on nutritional composition of Nannochloropsis salina biomass, with a focus on eicosapentaenoic acid (EPA). Variations in fatty acid composition, lipids, protein, amino acids, tocopherols and pigments were studied and results compared to algae cultivated on F/2 media as reference. Mixed growth media and process water enhanced the nutritional quality of Nannochloropsis salina in laboratory scale when compared to algae cultivated in standard F/2 medium. Data from laboratory scale translated to the large scale using a 4000 L flat panel photo-bioreactor system. The algae growth rate in winter conditions in Denmark was slow, but results revealed that large-scale cultivation of Nannochloropsis salina at these conditions could improve the nutritional properties such as EPA, tocopherol, protein and carotenoids compared to laboratory-scale cultivated microalgae. EPA reached 44.2% ± 2.30% of total fatty acids, and α-tocopherol reached 431 ± 28 µg/g of biomass dry weight after 21 days of cultivation. Variations in chemical compositions of Nannochloropsis salina were studied during the course of cultivation. Nannochloropsis salina can be presented as a good candidate for winter time cultivation in Denmark. The resulting biomass is a rich source of EPA and also a good source of protein (amino acids), tocopherols and carotenoids for potential use in aquaculture feed industry
Batch and Fed Batch Cultivation and Harvesting of Nannochloropsis Gaditana for Environmental Applications
Two challenging problems facing our world are the exhaustion of fossil fuels and climate change. Microalgae are eukaryotic phototrophs or prokaryotic cyanobacteria (blue green algae) that are able to capture CO2 and produce lipids suitable for biodiesel, thus can mitigate these challenges. The potential application of microalgae biomass for biofuel production is a clean and sustainable approach to replace fossil fuels. An important consideration for reducing the cost of biofuel is the economical production of algal biomass with high lipid yields. In this study, the marine microalgae Nannochloropsis gaditana were investigated for biomass and lipid production using two wastewater streams, i.e., road salt run-off and vegetable Greenhouse industry effluents as the growth media using batch or fed-batch cultivation. The recovery of biomass was also investigated using coagulants or pH change.
In the first phase of the research the effect of salinity on biomass concentration and lipid production was examined in the batch cultures. Increasing the concentration of salt in the nutrient road salt growth media increased the lipid content from 17% to 21.6% (w/w dry weight) which had the 70%(w/w) of long chain fatty acid, which are suitable for the biofuel production.
The fed-batch cultivation system was next applied to provide the nutrition sufficient, depletion and repletion conditions. Three different feeding strategies were examined: continuous, pulse and stage feeding for the effect on biomass and lipid yields. The best condition of the feeding regime was identified as pulse feeding based on the substrate to biomass conversion and lipid yield, which resulted the biomass of 2.08+/-0.03g. The increased light intensity doubled the lipid yields with the maximum of 58% (w/w) lipid content and the lipid productivity of 47mg/L/day was obtained.
The final phase of the study evaluated the flocculation methods to harvest the biomass from the growth media using two approaches: coagulant chemical addition and pH change. The pH values of 11-threshold pH for the alkaline flocculation of cells above, which the cells flocculate at the faster rate and the harvesting efficiencies over 90%, were achieved. The harvesting efficiency of 95% was achieved with ferric chloride with concentration factor of 23.5. The bio-coagulant chitosan was not effective to coagulate the cells
Assessment of microalgal biomass as a potential feedstock for sustainable, eco-friendly biostimulants and biopesticides in plant production
O uso excessivo e contínuo de agroquímicos, fertilizantes sintéticos e pesticidas, levou à poluição antropogénica de nutrientes, tendo causado um grande número de degradações ambientais. Além disso, os agroquímicos são poluentes ambientais que podem causar graves problemas de saúde humana. A expansão global de "zonas mortas" nos oceanos, nas quais os baixos níveis de oxigénio ameaçam a vida marinha, é apenas um dos muitos sinais de alerta de que medidas contrárias são necessárias com urgência. Os bioestimulantes e biopesticidas à base de microalgas representam uma alternativa promissora para alcançar uma maior sustentabilidade na agricultura moderna. A biomassa de microalgas contém numerosos aminoácidos e fitohormonas que promovem o crescimento das plantas, podendo aumentar a produtividade das culturas, estimulando o crescimento da raiz e da canópia. Além disso, sabe-se que as microalgas inibem o crescimento de vários agentes fitopatogénicos, devido às suas propriedades antimicrobianas, podendo ser uma alternativa sustentável aos pesticidas sintéticos no setor agrícola. Neste estudo, focámo-nos na aplicação de extratos aquosos de microalgas como fungicidas contra Sclerotium rolfsii, Rhizoctonia solani, Botrytis cinerea e Alternaria alternata. Esses fungos são agentes causais de doenças frequentes na agricultura, ameaçando a segurança alimentar global. As informações disponíveis, relacionadas com a utilização de microalgas na proteção de plantas e bioestimulação, são ainda escassas, embora as microalgas possam desempenhar um papel importante no desenvolvimento da agricultura sustentável. Secundariamente, sabendo-se que o uso agrícola de compostos de resíduos orgânicos apresenta vários benefícios relacionados com a fertilidade do solo e a resistência das plantas a algumas doenças, avaliou-se o efeito daquelas microalgas na compostagem de uma mistura de resíduos agrícolas comuns na região, devido à possibilidade de as microalgas poderem apresentar alguma influência na atividade microbiana responsável pela compostagem. O principal objetivo do presente estudo foi determinar as propriedades bioestimulantes e biofungicidas de microalgas e a sua capacidade de melhorar o processo de compostagem de resíduos orgânicos para um objetivo final de tornar a agricultura mais sustentável através do uso destes microrganismos fotossintéticos, nomeadamente Scenedesmus sp., Chlorella vulgaris, Nannochloropsis sp., Arthrospira (Spirulina) sp. e Phaeodactylum tricornutum. Para atingir o objetivo supracitado, os objetivos específicos desta dissertação são: (1) avaliar o controle de doenças de plantas com extratos aquosos de microalgas in vitro, e (2) avaliar e caracterizar processos de compostagem enriquecidos com microalgas.
O Capítulo II descreve a aplicação promissora de extratos aquosos de Nannochloropsis sp., Phaeodactylum tricornutum, Scenedesmus obliquus e Spirulina sp. in vitro para o desenvolvimento de antifúngicos de origem algal. A supressão do crescimento por estes extratos foi observada nos fungos fitopatogénicos Sclerotium rolfsii, Rhizoctonia solani e Botrytis cinerea. De facto, as espécies de microalgas são uma fonte promissora de agentes antifúngicos não prejudiciais ao meio ambiente que podem reduzir o uso de fungicidas sintéticos e limitar o impacto ecológico do setor agrícola. Uma vez que a maioria dos estudos se foca nas propriedades antifúngicas de cianobactérias procarióticas, o presente estudo visou preencher a lacuna de conhecimento sobre o uso de microalgas eucarióticas como agentes antifúngicos. Para evitar métodos complexos de extração e etapas de purificação, que aumentam os custos e restringem as aplicações em larga escala de fungicidas à base de algas, foi usada uma extração simples à base de água. Assim, foram investigadas as propriedades de extratos aquosos de microalgas eucarióticas (Nannochloropsis sp., Phaeodactylum tricornutum, Scenedesmus obliquus e Chlorella vulgaris) e procarióticas (Spirulina sp.) in vitro quanto à sua atividade inibidora em relação aos fungos fitopatogénicos Sclerotium rolfsii e Alternaria alternata. A análise estatística revelou que Scenedesmus obliquus apresentou a maior atividade antifúngica de todas as estirpes de microalgas contra Sclerotium rolfsii, com inibições de crescimento de até 32,01 ± 4,82%. Nannochloropsis sp. mitigou Sclerotium rolfsii em até 13,96 ± 5,26%, enquanto Phaeodactylum tricornutum suprimiu o crescimento de Sclerotium rolfsii e Rhizoctonia solani em até 18,35 ± 3,45% (p <0,05). Além disso, Phaeodactylum tricornutum e Scenedesmus obliquus inibiram o crescimento de Botrytis cinerea em até 11,47 ± 2,06% (p <0,05). Assim, esses resultados sugerem que microalgas com atividade fungicida podem contribuir para uma agricultura mais sustentável ao inibir o crescimento de fitopatógenos fúngicos.
No Capítulo III, encontra-se descrita a utilização de microalgas no processo de compostagem. Mais especificamente, este estudo investigou a suplementação de uma mistura de resíduos orgânicos com biomassa de microalgas secas de Nannochloropsis sp., Phaeodactylum tricornutum, Scenedesmus obliquus e Chlorella vulgaris. Até onde sabemos, este é o primeiro relatório que analisou o enriquecimento de materiais de compostagem frescos com pó de microalga seca. Uma vez que as microalgas produzem vários aminoácidos e fitohormonas que promovem o crescimento das plantas, seria de esperar que elas poderiam melhorar ainda mais as características dos compostos estimulantes das plantas, como a liberação de nutrientes que promovem o crescimento. As taxas de decomposição dependem das atividades metabólicas das populações microbianas que dependem, por sua vez, da disponibilidade de vários micro- e macronutrientes. Portanto, a co-compostagem de biomassa de microalgas rica em nutrientes poderá moldar comunidades microbianas e melhorar a qualidade do composto final com base na riqueza em nutrientes, como fósforo, azoto e potássio. Devido ao seu potencial para transformar e reciclar resíduos de diferentes origens em matéria orgânica, a compostagem terá um papel fundamental no caminho para uma sociedade mais sustentável. Em termos gerais, não foram observadas grandes variações nos parâmetros de pH, condutividade elétrica, matéria orgânica, matéria mineral, temperatura, volume e fitotoxicidade entre todas as pilhas de compostagem modificadas com microalgas, quando comparadas com o composto controlo (fase final). Portanto, o composto fortificado com microalgas poderá ser considerado uma alternativa sustentável promissora para aumentar ainda mais a produtividade das culturas no setor agrícola global, mas que requer ainda verificação experimental em ensaios de campo ou estufa.Continuous overuse of synthetic fertilizers and pesticides (agrochemicals) has led to excessive anthropogenic nutrient pollution and caused a vast number of environmental degradations. The global expansion of "dead zones" in the world's oceans, where oxygen-depleted water bodies threaten marine life, is just one of many warning signs indicating that counteractive measures are urgently needed. Moreover, long-term exposure to agrochemicals can cause major human health issues. Microalgae-based biostimulants and biopesticides represent a promising alternative to reduce those negative effects and achieve a higher sustainable value in modern agriculture. Microalgal biomass contains numerous plant growth-promoting amino acids and phytohormones that increase crop productivity by stimulating root and shoot growth. Compost can be seen as effective carrier for these bioactive compounds and may be applied as enriching soil amendment. Moreover, microalgae were found to inhibit the growth of several pathogens due to their antimicrobial properties. Hence, they can be seen as sustainable alternative for synthetic fertilizers and pesticides in the agricultural and horticultural sector. In this study we focused on the application of aqueous microalgal extracts as fungicides against the phytopathogenic fungi Sclerotium rolfsii, Rhizoctonia solani, Botrytis cinerea and Alternaria alternata. Those fungi are dominant causal agents for common diseases in agriculture and considered as major threat for global food security. Even though microalgae could play a major role in sustainable agriculture development, available literature related to microalgal crop protection and biostimulation is still scarce.
Chapter II describes the promising antifungal application of aqueous extracts from Nannochloropsis sp., Phaeodactylum tricornutum, Scenedesmus obliquus and Spirulina sp. in vitro. Growth suppression was observed against the phytopathogenic fungi Sclerotium rolfsii, Rhizoctonia solani and Botrytis cinerea. In Chapter III, no major parameter variations in pH, electrical conductivity, organic matter, mineral matter, temperature, volume and phytotoxicity were observed among all microalgae-amended composting piles, when compared with the control compost (final phase). Future studies will evaluate the biostimulant properties of these composts in vivo
Wastewater treatment with algae
Microalgae have been under investigation as alternatives for wastewater treatment for the last 60 years. However, we are yet to see an algal based process to be trusted as a treatment strategy on a large scale. At present, recycling of the wastewaters and nutrient utilization have been solidified as main objectives in wastewater treatment in European Union. The metabolism of microalgae and cyanobacteria enables them to assimilate and store inorganic nutrients in their biomass. Therefore, under the new wastewater treatment objectives microalgae might present a promising solution.
The present work investigates the possibility of using algal biomass grown in wastewater for the production of a high value compound eicosapentaenoic acid (EPA), a type of Omega-3 fatty acid. The heterokont microalgae Nannochloropsis oculata (Eustigmataceae) were successfully grown in wastewaters from a paper/pulp mill, and we show that EPA content stayed at the same level as in microalgae grown in control conditions.
Furthermore, a stable wastewater treatment process was established in an upscale tubular photobioreactor (PBR) with the microalgae Ettlia oleoabundans (Chlorophyceae), achieving 99.6 % and 75 % phosphate and ammonium removal efficiencies, respectively. The work points out the importance of wastewater pretreatment and wastewater optimization in order to achieve a reliable wastewater treatment process with microalgae.
Finally, the cyanobacterium Synechocystis sp. PCC6803 and its sigma factor mutants were investigated in order to evaluate potential stress induced by the wastewaters. The experiments revealed that sigma factor D (sigD) may play an important role in acclimation to wastewaters and its over expression might give an edge of the photosynthetic cells used for wastewater treatment in outdoor conditions.Levien käyttöä vaihtoehtoisena jätevedenpuhdistusmenetelmä on tutkittu jo 60 vuoden ajan, mutta suurimittakaavainen leväprosessi ei silti ole vielä missään käytössä. Euroopan Unioni pitää jätevesien kierrätystä ja niiden sisältämien ravinteiden talteenottoa jätevedenpuhdistuksen tärkeimpinä päämäärinä. Levät ja syanobakteerit ovat lupaava ratkaisuvaihtoehto jätevedenpuhdistukseen, koska niiden aineenvaihdunta mahdollistaa epäorgaanisten ravinteiden assimilaation ja varastoitumisen biomassaan.
Käsillä olevassa työssä tutkittiin mahdollisuutta jätevedessä tuotettavan leväbiomassan käyttämiseen eikosapentaeenihapon (EPA) tuottamiseen. EPA on markkina-arvoltaan merkittävä omega-3-rasvahappo. Heterokonta-ryhmään kuuluvan Eustigmataceae-heimon Nannochloropsis oculata -levää kasvatettiin onnistuneesti selluloosa- ja paperitehtaan jätevedessä, ja EPA:n määrä biomassassa säilyi levissä samalla tasolla kuin kontrollioloissa kasvatetuissa levissä.
Työssä rakennettiin stabiili jätevedenpuhdistusprosessi, jossa Ettlia oleoabundans -nimistä viherlevää (Chlorophyceae) kasvatettiin suuressa putkifotobioreaktorissa. Prosessi poisti jäteveden fosfaatista 99.6 % ja ammoniumista 75 %. Työ osoitti, että jäteveden esikäsittely ja ravinnepitoisuuden optimointi ovat toimivan käsittelyprosessin edellytyksiä.
Lopuksi työssä tutkittiin myös Synechocystis sp. PCC6803 -syanobakteerin ja erityisesti sen sigmatekijämutanttien toimivuutta jätevedenpuhdistuksessa erityisesti jäteveden aiheuttaman stressin kannalta. Kokeet osoittivat sigD-sigmatekijän näyttelevän tärkeää roolia syanobakteerin akklimaatiossa. Työn perusteella SigD:n ylituotto voisi parantaa syanobakteerin käyttömahdollisuuksia ulko-olosuhteissa
Cultivo de chlorella vulgaris em biorreator tipo raceway em água residual da extração de petróleo
A indústria do petróleo gera grandes volumes de água residual durante a extração, conhecida como água produzida (AP), que contém diversos poluentes. É necessário um tratamento eficiente antes de seu descarte ou reutilização, e a biorremediação com microalgas é uma abordagem promissora para esse fim. Esse trabalho tem como objetivo principal avaliar o potencial de biorremediação e produção de biomassa de Chlorella vulgaris utilizando água produzida suplementada como meio de cultivo em larga escala. Para isso foi realizado o cultivo de C. vulgaris em 30% de água produzida e 70% de meio BG-11, que resultou em uma produção significativa de biomassa (0,628 g L-1 controle e 0,601 g L-1 AP30) e síntese de biomoléculas de alto valor agregado, lipídios (6,14%), proteína (24,77%), carboidratos (3,67%) e pigmentos (6,24 μg mL-1 de clorofila a; 0,64 μg mL-1 de clorofila b e caratenoides totais 2,83 μg mL-1) para o cultivo AP30. A biomassa do cultivo AP30 apresentou composição ideal de ácidos graxos (62,78% de AGS, 12,55% de AGM e 24,69% de AGP) para a produção de biodiesel, além de contribuir para a biorremediação da água produzida, com alta eficiência na remoção de Zinco (100%); Cloreto (Cl-) 99,90%; Fosfato (PO4) 98,00% e Carbonatos (CaCO3) 80,73%. Desse modo, C. vulgaris mostrou ser uma alternativa promissora, não apenas para a biorremediação da água produzida, mas uma fonte potencial de biocombustíveis, promovendo uma abordagem sustentável e eficiente na gestão de resíduos industriais
Sustainable Aquaculture Techniques
This book presents some innovative developments in sustainable aquaculture practices in the context of environmental protection and seafood production techniques. The chapters are written by experts in their respective areas, so that their contribution represents the progress of their research, which is intended to mark the current frontier in aquaculture practices. Every chapter presents techniques that contribute to good aquaculture practices, where direct and vital nutrition and food, as a source of energy and biomass generation, is fundamentally based. We hope this book supports producers and researchers in their activities and helps to maintain a spirit of environmental protection in the context of production of high quality, nutritional food
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