Microalgae reactors, commonly known as photobioreactors, have become increasingly popular as an alternative for wastewater treatment. These systems reduce pollutants and remove nutrients such as nitrogen and phosphorous compounds from wastewater utilizing microalgae and bacteria. The biomass produced in the reactors can potentially be used to produce biofuels and decrease some of the energy demands of the process. Wastewater treating photobioreactors are a relatively new technology and many aspects of their microbiology need further study. This thesis presents a broad overview of the algal and bacterial communities present in these systems by looking at the most important species, metabolic pathways and growth dynamics of both algae and bacteria. The experiments presented in this thesis were conducted using municipal wastewater from the Västerås wastewater treatment plant. The wastewater was inoculated with algae from Lake Mälaren and compared to non-inoculated reactors. Overall, the inoculated reactors demonstrated better algal growth than those that were not inoculated. The tested systems also removed much of the ammonium and phosphorous present in the wastewater. The dominant algae in the tested systems belonged to the genera Scenedesmus, Desmodesmus and Chlorella. In addition to algae, the systems contained a large number of bacteria, mostly from the phyla Proteobacteria and Bacteroidetes. The algal photobioreactors contained a lower abundance of genes related to nitrogen metabolism, virulence and antibiotic resistance compared to the initial wastewater, showing that a shift in the bacterial community had occurred. The bacteria found in the systems were shown to be involved in synthesis of vitamins essential for algae growth such as vitamin B12, suggesting cooperation between the bacteria and algae. / I takt med att världens befolkning ökar, så produceras dagligen allt mer avfall. Detta kan orsaka stora problem för miljön. När det byggs nya system för vattenrening behöver vi även ta hänsyn till kravet att minska energiåtgången. Dagens vattenreningssystem har vissa tillkortakommanden när det gäller reningsnivåer och energianvändning. Ett alternativ till dagens system, kan vara fotobioreaktorer, dvs. vattenrening med hjälp av mikroalger. Dessa system använder mikroalger och bakterier för att rena vattnet från föroreningar, kväve och fosfor. Vattenrening med fotobioreaktorer är en relativt ny teknik. Flera aspekter gällande biologin i dessa system har ännu inte studerats i detalj. Den här avhandlingen presenterar en översikt av de alger och bakterier som är aktiva i fotobioreaktorer. Andra viktiga aspekter som tillväxt, arter samt vattenreningsförmåga har också studerats. Ett antal försök genomfördes där alger från Mälaren tillsattes i vatten från Västerås kommunala vattenreningsanläggning. Storleken på försöken varierade mellan 250 ml och 20 liter. Det visade sig att algerna hade en bra tillväxt samt att mängden ammonium och fosfor minskade i vattnet under försöksperioden. De alger som tillväxte mest i studien tillhörde Scenedesmus, Desmodesmus och Chlorella. Förutom alger tillväxte även ett stort antal bakterier från grupperna Proteobacteria and Bacteroidetes. Dessa bakterier visade sig syntetisera viktiga vitaminer, t.ex. vitamin B12, som algerna normalt inte kan syntetisera själva. Sammanfattningsvis, så presenterar denna avhandling viktig information gällande alger och bakterier i en fotobioreaktor. Informationen kan vara ett viktigt bidrag till framtida utveckling av storskaliga fotobioreaktorer för vattenrening.

Espécies de microalgas como Chlorella sorokiniana têm sido investigadas para as mais variadas aplicações como biocombustíveis, nutrição e a recuperação de nutrientes. Entretanto, a separação de microalgas do meio líquido permanece um desafio tanto técnico quanto econômico. O objetivo deste trabalho é propor e investigar a utilização de pré-ozonização e flotação por ar dissolvido para a separação sólido-líquido de Chlorella sorokiniana cultivada em meio padrão M8a em fotobiorreator flat panel, utilizando polímero catiônico à base de poliacrilamida como coagulante. Primeiramente, foi avaliado o sistema de tratamento com flotação por ar dissolvido, que foi otimizada em escala de laboratório visando eficiência de remoção de algas e flexibilização do sistema. Utilizando dosagens de polímero catiônico de 10 mg L-1 obteve-se remoções de cor aparente, turbidez e densidade óptica próximas de 95 % em pH 7. Posteriormente, a etapa de mistura lenta foi retirada do sistema, a razão de recirculação foi diminuída de 10 para 4 % e após essas alterações, obteve-se remoção de microalgas acima de 90 % para dosagem de polímero de 10 mg L-1. Para analisar o efeito da pré-ozonização a dosagem de polímero catiônico foi reduzida para 7 mg L-1, e observou-se que com FAD esta dosagem removeu 81,12 % de turbidez, e após pré-ozonização por 5 minutos seguida de FAD a eficiência de remoção de turbidez chegou a 91,78 % e remoção de cor aparente aumentou 6,25 %. A utilização da pré-ozonização permitiu utilização de velocidades de flotação da ordem de 24 cm min-1 sem prejuízo da eficiência de remoção de cor, turbidez e densidade óptica. Observou-se que a pré-ozonização demonstra efeitos positivos no sistema de tratamento, mas constatou-se uma dosagem ótima de ozônio, e que a partir desta dosagem a eficiência do tratamento pode ser prejudicada. Foi constatado que uma possível explicação para esse fato seja a liberação de matéria orgânica algal após pré-ozonização, em dosagens acima do valor ótimo de dosagem de ozônio. / Microalgal species as Chlorella sorokiniana have been investigated for a variety of applications such as biofuels, nutrition and nutrient recovery. However, the solid-liquid separation microalgae of the liquid medium remains a challenge both technical as economical. This work aims to propose and investigate the use of preozonation and dissolved air flotation for solid liquid separation of Chlorella sorokiniana cultivated in standard M8a medium in a flat panel photobioreator, using cationic polyacrylamide based polymer as coagulant. Initially, treatment system including dissolved air flotation was evaluated, which was optimezed at laboratory scale targeting removal efficiency of microalgae and system flexibility. Using cationic polymer dosage of 10 mg L-1, were obtained apparent color, turbidity and optical density removals nearly to 95% in pH 7. Further, the step of slow mixing was removed from the system, the recycle ratio was decreased from 10 to 4% and after these changes, was obtained microalgae removal over 90% at polymer dosage of 10 mg L-1. To analyse the effect of preozonation, cationic polymer dosage was decreased to 7 mg L-1, and was observed 81.12 % turbidity removal with this polymer dosage at FAD, and after 5 minutes preozonation followed by FAD, turbidity removal efficiency reached 91.8 % and apparent color removal increased 6.25 %. The utilization of preozonation allowed use of flotation velocities in the order of 24 cm min-1 without damaging variables removal efficiency. It was observed tha preozonation shows positive effects in treatment system, but was found an optimum ozone dosage from which the treatment efficiency is hampered. It was observed that a possible explanation to this fact is the release of algogenic organic matter after preozonation in dosages over the optimum value of ozone dosage.

Production of hydrogen from biomass through the use of dark and photofermentative bacteria will be applicable in the future and a promising route. The aim of this study is to develop and to scale-up solar panel photobioreactors for the biological hydrogen production by photosynthetic purple non sulfur (PNS) bacteria on artificial substrates and on real dark fermentation effluent of molasses. The parameters studied are light intensity, temperature, feed stock, feed rate, pH, cell density, light and dark cycle and carbon to nitrogen ratio on hydrogen production. Continuous hydrogen production has been achieved on artificial medium and dark fermentor effluent of molasses containing acetate and lactate by Rhodobacter capsulatus wild type and (hup-) mutant strains in panel photobioreactors in indoor and outdoor conditions by fed batch operation. Laboratory (from 4 to 8 liters) and large scale (20 L) panel photobioreactors by using various designs and construction materials were developed. In this photobioreactors continuous hydrogen production was achieved by feeding. Na2CO3 can be used as buffer to keep the pH stable during long term operation on molasses dark fermentor effluent. The adjustment of the feedstock by dilution and buffer addition were found to be essential for the long term stability of pH, biomass and H2 production for both in indoor and outdoor applications.

This Ph.D. thesis deals with principles of microalgae cultivation in laboratory as well as outdoor aquacultures (Chapter 1) using various cultivation systems and photobioreactors (Chapter 2). Case studies illustrate the main research topic as to correlate changes in growth rate with variation of photosynthetic activity, physiological features and biomass composition (Chapter 3). Special attention was paid to elaboration of protocols of chlorophyll a fluorescence techniques for monitoring the physiology and photosynthetic performance of microalgae mass cultures maintained under various growth conditions (Chapter 4).

Espécies de microalgas como Chlorella sorokiniana têm sido investigadas para as mais variadas aplicações como biocombustíveis, nutrição e a recuperação de nutrientes. Entretanto, a separação de microalgas do meio líquido permanece um desafio tanto técnico quanto econômico. O objetivo deste trabalho é propor e investigar a utilização de pré-ozonização e flotação por ar dissolvido para a separação sólido-líquido de Chlorella sorokiniana cultivada em meio padrão M8a em fotobiorreator flat panel, utilizando polímero catiônico à base de poliacrilamida como coagulante. Primeiramente, foi avaliado o sistema de tratamento com flotação por ar dissolvido, que foi otimizada em escala de laboratório visando eficiência de remoção de algas e flexibilização do sistema. Utilizando dosagens de polímero catiônico de 10 mg L-1 obteve-se remoções de cor aparente, turbidez e densidade óptica próximas de 95 % em pH 7. Posteriormente, a etapa de mistura lenta foi retirada do sistema, a razão de recirculação foi diminuída de 10 para 4 % e após essas alterações, obteve-se remoção de microalgas acima de 90 % para dosagem de polímero de 10 mg L-1. Para analisar o efeito da pré-ozonização a dosagem de polímero catiônico foi reduzida para 7 mg L-1, e observou-se que com FAD esta dosagem removeu 81,12 % de turbidez, e após pré-ozonização por 5 minutos seguida de FAD a eficiência de remoção de turbidez chegou a 91,78 % e remoção de cor aparente aumentou 6,25 %. A utilização da pré-ozonização permitiu utilização de velocidades de flotação da ordem de 24 cm min-1 sem prejuízo da eficiência de remoção de cor, turbidez e densidade óptica. Observou-se que a pré-ozonização demonstra efeitos positivos no sistema de tratamento, mas constatou-se uma dosagem ótima de ozônio, e que a partir desta dosagem a eficiência do tratamento pode ser prejudicada. Foi constatado que uma possível explicação para esse fato seja a liberação de matéria orgânica algal após pré-ozonização, em dosagens acima do valor ótimo de dosagem de ozônio. / Microalgal species as Chlorella sorokiniana have been investigated for a variety of applications such as biofuels, nutrition and nutrient recovery. However, the solid-liquid separation microalgae of the liquid medium remains a challenge both technical as economical. This work aims to propose and investigate the use of preozonation and dissolved air flotation for solid liquid separation of Chlorella sorokiniana cultivated in standard M8a medium in a flat panel photobioreator, using cationic polyacrylamide based polymer as coagulant. Initially, treatment system including dissolved air flotation was evaluated, which was optimezed at laboratory scale targeting removal efficiency of microalgae and system flexibility. Using cationic polymer dosage of 10 mg L-1, were obtained apparent color, turbidity and optical density removals nearly to 95% in pH 7. Further, the step of slow mixing was removed from the system, the recycle ratio was decreased from 10 to 4% and after these changes, was obtained microalgae removal over 90% at polymer dosage of 10 mg L-1. To analyse the effect of preozonation, cationic polymer dosage was decreased to 7 mg L-1, and was observed 81.12 % turbidity removal with this polymer dosage at FAD, and after 5 minutes preozonation followed by FAD, turbidity removal efficiency reached 91.8 % and apparent color removal increased 6.25 %. The utilization of preozonation allowed use of flotation velocities in the order of 24 cm min-1 without damaging variables removal efficiency. It was observed tha preozonation shows positive effects in treatment system, but was found an optimum ozone dosage from which the treatment efficiency is hampered. It was observed that a possible explanation to this fact is the release of algogenic organic matter after preozonation in dosages over the optimum value of ozone dosage.

Dissertação(mestrado)- Universidade Federal do Rio Grande, Programa de Pós-Graduação em Engenharia e Ciência de Alimentos, Escola de Química e Alimentos, 2010. / Submitted by Caroline Silva (krol_bilhar@hotmail.com) on 2012-08-30T16:18:53Z No. of bitstreams: 1 dissertao adriano arruda henrard.pdf: 1485086 bytes, checksum: f5665b2804865ca150fc4f99a546ffe6 (MD5) / Approved for entry into archive by Bruna Vieira(bruninha_vieira@ibest.com.br) on 2012-09-03T19:18:51Z (GMT) No. of bitstreams: 1 dissertao adriano arruda henrard.pdf: 1485086 bytes, checksum: f5665b2804865ca150fc4f99a546ffe6 (MD5) / Made available in DSpace on 2012-09-03T19:18:51Z (GMT). No. of bitstreams: 1 dissertao adriano arruda henrard.pdf: 1485086 bytes, checksum: f5665b2804865ca150fc4f99a546ffe6 (MD5) Previous issue date: 2009 / As microalgas se destacam por apresentarem diversas potencialidades, como fonte de alimento, obtenção de bioprodutos, produção de biocombustíveis e também podem contribuir na redução do efeito estufa, fixando CO2. As microalgas apresentam em sua composição alto teor de proteínas, ácidos graxos, minerais e pigmentos e, além disso, a microalga Chlorella possui certificado GRAS (Generally Recognized As Safe), podendo ser utilizada como alimento sem oferecer risco à saúde humana. Industrialmente, o cultivo semicontínuo de microalgas é muito empregado, pois com esse tipo de cultivo é possível a manutenção da cultura em crescimento por períodos mais prolongados, procedendo-se apenas a alimentação periódica do meio novo. O objetivo deste trabalho foi estudar o crescimento das microalgas Cyanobium sp. e Chlorella sp. cultivadas em modo semicontínuo e diferentes condições nutricionais e de processo. Assim, este trabalho foi dividido em 3 etapas: na primeira, objetivou-se estudar os cultivos das microalgas Cyanobium sp. e Chlorella sp. em diferentes condições nutricionais e de processo; na segunda etapa, avaliou-se o cultivo semicontínuo da microalga Cyanobium sp. em fotobiorreator tubular vertical de 2 L e na terceira, estudou-se o cultivo da microalga Chlorella sp. em modo semicontínuo em fotobiorreator aberto tipo raceway de 6 L. Para avaliar o melhor meio nutriente e agitação, os cultivos foram realizados em fotobiorreatores tipo erlenmeyer e raceway de 0,5 L e 6 L, respectivamente. Os cultivos foram realizados em condições controladas, estufa climatizada a 30ºC, 3200 Lux e fotoperíodo 12 h claro/escuro. O melhor meio de cultivo para as microalgas Cyanobium sp. e Chlorella sp. foi o meio BG11 com adição de bicarbonato de sódio, onde foram obtidas as maiores concentrações celulares (0,56 e 0,66 g.L-1), velocidades específicas de crescimento (0,303 e 0,166 d-1) e produtividades (0,120 e 0,089 g.L-1.d-1), respectivamente. Quando cultivadas sob diferentes agitações, as melhores respostas foram obtidas nos ensaios realizados com agitação por 2 bombas submersas, com concentrações máximas de biomassa 1,21 e 0,93 g.L-1 para Cyanobium sp. e Chlorella sp, respectivamente. Para o cultivo em modo semicontínuo da microalga Cyanobium sp., a máxima velocidade específica de crescimento foi 0,127 d-1 quando o cultivo foi realizado com concentração de corte 1,0 g.L-1, taxa de renovação 50% e concentração de bicarbonato de sódio 1,0 g L-1. Os máximos valores de produtividade (0,071 g.L-1.d-1) e número de ciclo (10) foram observados em concentração de corte 1,0 g.L-1, taxa de renovação 30% e concentração de bicarbonato 1,0 g.L-1. No cultivo semicontínuo com Chlorella sp., a maior velocidade específica de crescimento (0,149 d-1) foi obtida quando cultivada com 1,6 g.L-1 de bicarbonato de sódio e concentração de corte 0,6 g.L-1. A maior produtividade (0,091 g.L-1.d-1) foi obtida quando utilizado no cultivo concentração de corte 0,8 g.L-1, taxa de renovação de meio 40% e concentração de bicarbonato de sódio 1,6 g.L-1. Os resultados mostraram que o cultivo em modo semicontínuo é uma alternativa para maximizar a produção de microalgas, além disso, o sistema de cultivo deve ser escolhido não apenas pela maior produtividade, mas também de acordo com as características desejadas do produto. / Microalgae had gain attention for presenting diverse potentialities, as source of food, attainment of bioproducts, produce biofuels and also can contribute in the greenhouse effect reduction, fixing CO2. Microalgae presents in its composition high contents of protein, fatty acids, minerals and pigments, moreover, microalgae Chlorella possess the GRAS (Generally Recognized As Safe) certificate, being able to be used as food without offering any risk to the human health. The semicontinuous microalgae cultivation is very used, because of the long period cells maintenance, being necessary the periodic feeding of new cultivation medium. The objective of this work was to study the growth of the microalgae Cyanobium sp. and Chlorella sp. cultivated in semicontinuous mode and different nutritional and process conditions. This work was divided in three stages: in the first, the aim was to study the cultivation of the microalgae Cyanobium sp. and Chlorella sp. in different nutritional and process conditions; in the second stage, the semicontinuous cultivation of the microalgae Cyanobium sp. in vertical tubular photobioreactor of 2 L was evaluated; in the third, the culture of the microalgae Chlorella sp. was studied in semicontinuous mode in open photobioreactor type raceway of 6 L. To evaluate the best medium nutrient and agitation conditions, cultures were carried out under in photobioreactors type erlenmeyer and raceway of 0,5 L and 6 L, respectively. Cultures were carried out under controlled conditions, climatized greenhouse at 30ºC, 3200 Lux and 12 h photoperiod light/dark. The best culture medium for the microalgae Cyanobium sp. and Chlorella sp. was the BG11 medium with sodium bicarbonate addition, where were obtained the highest cell concentrations (0,56 and 0,66 g.L-1), specific growth rate (0,303 and 0,166 d-1) and productivity (0,120 and 0,089 g.L- 1.d-1), respectively. When cultivated under different agitation conditions, the best answers were obtained with agitation given by 2 submerged pumps, with maximum biomass concentrations 1,21 g.L-1 for Cyanobium sp. and 0,93 g.L-1 for Chlorella sp. For the culture in semicontinuous mode of the microalga Cyanobium sp., the maximum specific growth rate was 0,127 d-1 in the culture with cell concentration 1,0 g.L-1, renewal rate 50% and sodium bicarbonate concentration 1,0 g.L-1. The maximum productivity values (0.071 g.L-1.d-1) and cycle number (10) had been observed in cell concentration 1,0 g.L-1, renewal rate 30% and 1,0 g.L-1 bicarbonate concentration. In the semicontinuous culture with Chlorella sp., the highest specific growth rate (0,149 d-1) was gotten when cultivated with 1,6 g.L-1.d-1 of sodium bicarbonate and cell concentration 0,6 g.L-1). The highest productivity (0,091 g.L-1.d-1) was gotten when cell concentration 0,8 g.L-1, medium renewal rate 40% and sodium bicarbonate concentration 1,6 g.L-1 were used in the culture. Results had shown that semicontinuous mode culture is an alternative to maximize the microalgae production, moreover, the culture system must not only be chosen by the highest productivity, but also in accordance with the desired characteristics of the product.

Presented diploma thesis is focused on the optimisation of Haematococcus pluvialis cultivations in different photobioreactors and on biotechnological production of astaxanthin. Theoretical part summarized the knowledge about optimal growth and production conditions of secondary metabolites. Followed research was focused on actual cultivation systems and on the possibilities of metabolite and nutrient monitoring. In experimental part the growth characteristic of the strain from Březova nad Svitavou (HMP-CCALA 375) was analyzed under optimal cultivation conditions on white and red light. During culture growth the profile and the concentration of carotenoid pigments were determined. The best yield of biomass was achieved in the cultivation on white light (0,939 g/l),carotenoids lutein and -carotene were observed as dominant pigments. In the next experiments optimal growth medium, temperature and light intensity were determined for cultivations of four chosen HMP strains from Germany, America, Africa and Switzerland. The most suitable cultivation medium was found BBM, oppositely the worst results were obtained with BG11. In previous experiments cultivation temperature 22 °C was determined as optimal value for comparative strain HMP – CCALA 375. Selected four strains were cultivated at 22 °C, as well as at 25 °C. Higher temperature was more optimal mainly for Switzerland, German and Africa strains. By analyzing of light intensity influence, it was found that the best increase of biomass was induced by the adaptation of culture on lower illumination (50 µmol photones•m^-2•s^-1) followed by higher light intensity (100 - 150 µmol photones•m^-2•s^-1). HMP from Switzerland showed the best growth results during all cultivation experiments, so this strain could be perhaps useful for industrial production of astaxanthin. In the last part of work, the influence of stress conditions on astaxanthin production by strain from Březova nad Svitavou (HMP – CCALA 375) was studied. Followed stress factors were used: high intensity of light (1 000 µmol photones•m^-2•s^-1), low nitrogen concentration (32,96 mg/l), addition of sodium chloride (0,5%), influence of sodium acetate (2,2 mM) and combination of sodium chloride and sodium acetate (0,5% NaCl, 2mM NaAc). Due to strong illumination (1 000 µmol photones•m^-2•s^-1) the best yield of astaxanthin was obtained (more than 20 mg/g). According to literature [103, 105] significant amount was also observed by addition of sodium acetate (9,2 mg/g). Oppositely minimal astaxanthin production was showed in presence of salt stress (3,8 mg/g). In followed experiments should be studied the influence of stress combinations on HMP – CCALA 375 strain as well as on other suitable strains of H. pluvialis with the aim to achieve the maximal yield of astaxanthin significant for large scale cultivation.

No description available.

M. Tech (Biosciences, Faculty of Applied and Computer Sciences), Vaal University of Technology. / The mass production of algae for commercial purposes has predominately been carried out in open ponds systems. However, open ponds systems have a number of disadvantages such as poor light utilization, requirement for large areas of land and high risks of contamination. On the other hand, photobioreactors have attracted much interest because they allow a better control of the cultivation conditions than open systems. With photobioreactors, higher biomass productivities are obtained and contamination can be easily prevented. Photobioreactors can also be engineered to manipulate the light and dark photosynthetic reactions thus enhancing biomass productivity. The main objective of this study was to construct a novel tubular photobioreactor which had the ability to expose the cultured alga to light and dark phases with the aim of optimizing the algal biomass production. A novel tubular photobioreactor with the ability to manipulate the cultured alga’s light and dark photosynthetic reactions was constructed in this study. The alga Spirulina platensis was chosen as the test organism in this novel tubular photobioreactor due to a number of reasons such as its globally socioeconomic importance, its tolerance of higher pH and temperature values which makes it almost impossible to contaminate. The cultivation process of Spirulina in the photobioreactor was investigated through alternating light and dark cycles in an attempt to increase the photosynthetic efficiency of the culture. The effect of different light intensities on the growth of Spirulina in the novel tubular photobioreactor was investigated and it was found that the best light condition that favored higher biomass formation was at 600 μ mol m-2 s-1. Five different light/ dark ratios were evaluated at a light intensity of 600 μ mol m-2 s-1 during a batch mode of operation of the novel tubular photobioreactor. The light/ dark ratio of 1:0.25 was found to be the best ratio because it gave the highest biomass in the shortest period of time when compared to the other ratios used. These results seem to suggest that longer light cycle relative to dark cycle results in higher biomass production. The ratio of 1:0.25 was then used to operate the novel tubular photobioreactor in a continuous mode. A maximum biomass productivity of 25 g/m2/day was achieved which corresponded to a net photosynthetic efficiency of 5.7 %. This result was found to be higher than what most photobioreactors could achieve but it was 2.8 g/m2/day lower than the highest ever reported productivity in a photobioreactor when Spirulina is cultivated. The 2.8 g/m2/day lower was attributed to the different materials used in the construction of these two photobioreactors. The photobioreactor which achieved 27.8 g/m2/day was made up of a clear glass whereas the novel tubular photobioreactor was made up of a PVC tubing. PVC tubes tend to change from clear to a milky colour after a certain period when it is used at higher temperature and pH values hence blocks a certain amount of light. Therefore the main recommendation in this study is to use a PVC tubing with a longer life span when used at a higher temperature and pH values.

No description available.