Academic literature on the topic 'Microalgae valorisation'

PurposeThe purpose of this paper is to acquaint the readers with the insights regarding the interventions of microalgal technology for production of metabolites and functional ingredients from microalgae for food and nutraceutical application and exploration of microalgae biomass for food application.Design/methodology/approachVarious information databases such as journals, library catalogues and professional websites were used to collect information pertaining to application of microalgae in food and nutraceutical sector. Systematic review was made with recent studies covering the vital aspects of art of microalgae cultivation for metabolite production, functional ingredients from microalgae, market scenario and utilisation of microalgae biomass for the valorisation of the food products. Key points have been discussed after every section to highlight the practical implications to make this review more insightful for the readers.FindingsMicroalgal technology provides sustainable solution for its application in food and nutraceutical sector. The heart of metabolite production lies in the optimisation of cultivation conditions of microalgae. Wide array of functional components are obtained from microalgae. Microalgae offer an alternative source for omega-3 fatty acids. Microalgae is widely exploited for production of pigments, namely, ß-carotene, astaxanthin, lutein, phycocyanin and chlorophyll, that have important implication as natural colourants and nutraceuticals in food. Larger diversity of sterols found in microalgae confers bioactivity. Microalgae is finding its place in market shelves as nutraceuticals where its functional ingredients are in the form of powder, tablets, extract and beverages and in innovative products such as microalgae protein and fat, culinary algae oil and butter. Sprulina and Chlorella are popular choice for the supplementation of food products with microalgae biomass.Originality/valueThis is a comprehensive review that highlights the application of microalgal technology for the development of healthy food products and presents holistic intervention in food and nutraceutical sector.

Abstract This study evaluates the feasibility of advanced biofilm microalgae cultivation in a twin layer (TL) system for nutrient removal (N and P) as the tertiary treatment in small wastewater treatment plants (WWTPs) located in sensitive areas. Furthermore, the potential valorisation of microalgae biomass as a component of bio-based fertilizers is assessed. Scenedesmus sp. was chosen among 33 microalgae strains for inoculation of TL due to its high growth rate and its nutrient uptake capacity. The tests carried out in the prototype were markedly efficient for total soluble and ammoniacal nitrogen removal (up to 66 and 94%, respectively). In terms of potential valorisation of microalgae, the nutrient content was 5.5% N (over 40% protein), 8.8% P2O5 and 1.5% K2O, high enzymatic activity, very low levels of heavy metals and no detectable pathogen presence. However, in the formulation of solid-state bio-based fertilizers, the microalgae proportions in blends of over 2% of microalgae led to negative effects on ryegrass (Lolium perenne L. ssp.) and barley (Hordeum vulgare ssp.). The obtained results demonstrate that TL represents a promising technology, which allows efficient tertiary treatment of urban wastewater and the production of high-quality bio-based fertilizer.

Natural resources are becoming increasingly scarce, and the need to control their consumption and recycle their use is growing. Water is one of the essential resources for human survival. Therefore, there has been an increasing interest in ways to save, recycle and treat water supplies. Aquaculture is one of the most polluting activities as it produces a significant wastewater volume, which needs proper treatment before being discharged into the environment or recycled. Microalgae are a potential solution for wastewater treatment. Due to their numerous advantages, the use of microalgal biomass is being studied, and, at present, there is already a market and room for profit in the sale of microalgal components in various forms, such as animal and human supplements. From a biorefinery point of view, it is important to take advantage of all the qualities and benefits that microalgae have by combining their great capacity to treat wastewater and exploit the produced biomass, analysing its composition for subsequent valorisation, for example. In this study, Chlorella vulgaris was used to treat aquaculture wastewater from a trout farm aquaculture facility, and the treatment efficiency was evaluated. To valorise the resulting biomass, its composition was also assessed. C. vulgaris successfully grew in the effluent with growth rates of 0.260 ± 0.014 d−1 and with average productivity of 32.9 ± 1.6 mg L−1 d−1. The achieved removal efficiencies were 93.5 ± 2.1% for total nitrogen, 98.0 ± 0.1% for nitrate-nitrogen and 92.7 ± 0.1% for phosphate-phosphorus. Concerning biomass composition, the lipids (15.82 ± 0.15%), carbohydrates (48.64 ± 0.83%), and pigment contents (0.99 ± 0.04% for chlorophyll a + b and 0.21 ± 0.04% for carotenoids) were similar to the values of similar studies. However, the protein content obtained (17.93 ± 1.21%) was lower than the ones mentioned in the literature.

In view of the valorisation of the green microalga Scenedesmus obliquus biomass, it was used for the biosorption of two nonsteroidal anti-inflammatory drugs, namely salicylic acid and ibuprofen, from water. Microalgae biomass was characterized, namely by the determination of the point of zero charge (pHPZC), by Fourier transform infrared (FT-IR) analysis, simultaneous thermal analysis (STA) and scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS). Kinetic and equilibrium batch experiments were carried out and results were found to fit the pseudo-second order equation and the Langmuir isotherm model, respectively. The Langmuir maximum capacity determined for salicylic acid (63 mg g−1) was larger than for ibuprofen (12 mg g−1), which was also verified for a commercial activated carbon used as reference (with capacities of 250 and 147 mg g−1, respectively). For both pharmaceuticals, the determination of thermodynamic parameters allowed us to infer that adsorption onto microalgae biomass was spontaneous, favourable and exothermic. Furthermore, based on the biomass characterization after adsorption and energy associated with the process, it was deduced that the removal of salicylic acid and ibuprofen by Scenedesmus obliquus biomass occurred by physical interaction.

Wastewaters are mainly classified as domestic, industrial and agro-industrial based on their production source. Piggery wastewater (PWW) is a livestock wastewater characterized by its high concentrations of organic matter and ammonium, and by its odour nuisance. Traditionally, PWW has been treated in open anaerobic lagoons, anaerobic digesters and activated sludge systems, which exhibit high greenhouse gas emissions, a limited nutrients removal and a high energy consumption, respectively. Photosynthetic microorganisms can support a sustainable wastewater treatment in engineered photobioreactors at low operating costs and with an efficient recovery of carbon, nitrogen and phosphorous. These microorganisms are capable of absorbing solar irradiation through the photosynthesis process to obtain energy, which is used for their growth and associated carbon and nutrients assimilation. Purple phototrophic bacteria (PPB) represent the photosynthetic microorganisms with the most versatile metabolism in nature, whereas microalgae are the most-studied photosynthetic microorganisms in recent years. This review describes the fundamentals, symmetry and asymmetry of wastewater treatment using photosynthetic microorganisms such as PPB and microalgae. The main photobioreactor configurations along with the potential of PPB and microalgae biomass valorisation strategies are also discussed.

Les microalgues présentes à la fois dans les eaux douces et salées compteraient plus de 200 000 espèces. Cette diversité en fait une source potentielle de métabolites spécialisés originaux. Parmi les principales familles de substances naturelles valorisées actuellement, on peut citer les pigments, lipides, protéines, polysaccharides, caroténoïdes. Une vision plus globale du métabolome de chacune des espèces apparaît aujourd’hui nécessaire pour mieux mettre en valeur le potentiel commercial que représente cette « microbiodiversité ». Pour cela, nous avons tout d’abord choisi d’approcher le métabolome de différentes souches de microalgues cultivées au sein de la Société Greensea en s’appuyant sur les techniques d’HPTLC, de RMN et d’UHPLC-QTOF pour une visualisation large. Cette étude nous a permis de regrouper les espèces par analogie métabolique après traitement statistique des données. Une seconde partie a consisté en une étude phytochimique approfondie de certaines souches et a conduit à l’isolement et la caractérisation de plusieurs molécules. Ainsi, en plus de métabolites connus, un peptide original portant un motif isoprényl, le cumbriamide a été caractérisé au sein de Lyngbya sp. et une première évaluation de son potentiel thérapeutique a été entreprise. Une large diversité en glycolipides s’est montrée prépondérante dans de nombreuses souches et une méthode de caractérisation a pu être mise au point pour leur identification par UHPLC-QTOF. Enfin, différentes applications des approches métabolomiques ont été envisagées. Ainsi, des études chimiotaxonomiques ont été menées sur les différentes souches de microalgues et l’influence de changements de conditions de culture sur la production de métabolites chez Nannochloropsis oculata a été observée
Microalgae are present both in Oceans and freshwaters and could include more than 200 000 species. This diversity is a source of original specialized metabolites that can find a large array of applications. Pigments, lipids, proteins, polysaccharides and carotenoids are usual compounds produced by microalgae that have found commercial applications. A global vision of the metabolome of each species has showed promises to highlight the commercial value of this “microdiversity”. We then decided to assess the metabolome of several microalgae species grown at the Greensea company by using HPTLC, NMR and UHPLC-QTOF techniques for a rapid and global overview. A classification of the species according to their metabolomics similarities was obtained after statistics treatment of the data. A second part was dedicated to a phytochemical study of the extracts of selected strains and led to the isolation and characterization of several metabolites. Thus, in addition to known molecules, an original peptide substituted by an isoprenyl moiety and named cumbriamide has been characterized in Lyngbya sp and a first assessment of its therapeutical potential has been undertaken. Glycolipids have been identified as the major metabolites in the extracts of numerous strains and a UHPLC-QTOF method was developed for their identification. Finally, several applications of the metabolomics approaches were considered. Chemotaxonomic studies were first carried out and the influence of growth conditions on the metabolome of Nannochloropsis oculata was observed

Les secteurs de la parfumerie et de la cosmétique occupent une place proéminente dans la société moderne. De nombreuses entreprises se positionnent depuis plusieurs années sur les produits cosmétiques à ingrédients naturels. Les plantes, longtemps considérées comme matière première principale pour le domaine de la cosmétique, sont aujourd’hui concurrencées par les microalgues dont la biomasse devient plus facile à obtenir grâce aux avancées en biotechnologie bleue. Ainsi, Cosmo International Ingredients se positionne à travers cette thèse pour élargir son panel de matières premières valorisables dans le domaine de la cosmétique. Dans un premier temps, l’étude phytochimique de microalgues péruviennes a permis d’isoler et identifier une famille majeure de métabolites chez les microalgues : les glycolipides. Une recherche de conditions d’extraction optimale pour cette famille a été effectuée et a permis de proposer une méthodologie verte, spécifique et peu coûteuse. Les cyanobactéries connues pour leur production de métabolites structurellement diversifiés ont été sélectionnées pour la culture suivant des critères spécifiques. Cette approche a permis d’isoler et de caractériser 5 composés à forte valeur ajoutée dont 4 peptides et un alcaloïde. Enfin, un forçage métabolique a été effectué sur Microcystis aeruginosa afin d’optimiser la production des 4 peptides cibles. Il en est ressorti que les paramètres température et intensité lumineuse jouent un rôle important dans la production peptidique
The sectors of fragrances and cosmetics play a prominent role in the modern society. During the last decades, several companies have been focusing on nature to provide innovative products. Plants have historically been considered the main raw material in the cosmetic field but, recently, microalgae have been identified as a worthy competitor due to the facility to obtain biomass. Thus, the company Cosmo International Ingredients supported this PhD. thesis to broaden their range of raw materials that can be used for the cosmetic industry. First, the phytochemical study of Peruvian microalgae allowed the isolation of a major family of metabolites: glycolipids. An environmentally-friendly, selective and low-cost method for their extraction from the biomass has been developed. Cyanobacteria known for their production of structurally diverse metabolites have been selected for culture following specific criteria; as a result 5 compounds have been isolated and fully characterized, 4 of which were peptides and one was an indole alkaloid. Finally, to optimize the production of the targeted bioactive peptides, a kinetic study was performed for 3 different temperatures and 3 different light intensities. These parameters were found to play a critical role for the peptide production

La biomasse des microalgues tropicales a des vertus naturelles qui peuvent être utilisées dans une large gamme de bioproduits. Leur valorisation peut permettre une production durable et commercialement viable. En effet, les microalgues tropicales représentent une grande biodiversité et bénéficient de conditions environnementales favorables à une production à grande échelle. Dans ce contexte, cette thèse vise à étudier de nouvelles souches tropicales afin de connaître leur potentiel de valorisation dans le domaine des biotechnologies, et plus particulièrement sur trois aspects : énergie, nutraceutique et antifouling. Ce dernier domaine a été étudié dans le cadre du projet ANR-CD2I « BIOPAINTROP » dont l’objectif est la lutte écoresponsable contre le biofouling. Ces travaux s’orientent vers des applications biotechnologiques, mais aussi vers le développement des nouvelles méthodes de caractérisation de l’activité antifouling. Sur les 50 souches étudiées, certaines ont montré la production de métabolites d'intérêt tels que le glycosylglycerol, des lipides de qualité pour la nutraceutique et la production de biodiesel. La souche Amphidinium sp. (P-43) a conduit à un extrait méthanolique possédant une activité biologique significative. Son efficacité dans la lutte contre le biofilm a été démontrée. De plus, l'étude d'écotoxicologie réalisée laisse présager d'un faible impact environnemental
Biomass of tropical microalgae have natural virtues that can be used in a wide range of bioproducts. Their valuation can enable sustainable and commercially viable production. Indeed, tropical microalgae represent a large biodiversity and benefit from favourable environmental conditions for large scale production. In this context, this thesis aims to explore new tropical strains to determine their potential development in the field of biotechnology, particularly in three areas: energy, nutraceutical and antifouling. This field is studied in the project ANR-CD2I "BIOPAINTROP" whose objective is the eco-responsible fight against biofouling. These works target biotechnological applications, but also development of new methods to characterize antifouling activity.Of the 50 strains studied, some have shown interest in the production of metabolites such as glycosyl glycerol, quality nutraceutical and lipids for biodiesel production. The Amphidinium sp. (P-43) stain led to a methanol extract having biological activity of interest. Its efficiency against biofilm was demonstrated. Moreover, the ecotoxicology study has suggested a low environmental impact

Les tecnologies basades en microalgues ofereixen una solució prometedora per canviar l’enfoc del tractament de residus i aigües residuals cap a la recuperació d’energia i recursos. Les microalgues consumeixen els nutrients en les aigües residuals i produeixen oxigen, utilitzat pels bacteris per biodegradar la matèria orgànica. Aquests processos s’han implementat amb èxit pel tractament de les aigües residuals urbanes, però en ciutats cada cop més industrialitzades i en entorns agrícoles, el repte actual és determinar si aquests sistemes poden degradar contaminants orgànics com els pesticides. La biomassa algal produïda pot valoritzar-se per a la producció de biofuels i altres subproductes valuosos. En aquest sentit, la digestió anaeròbia és una de les tecnologies millor desenvolupades i implementades per a convertir residus orgànics en energia renovable. Alhora, la co-digestió simultània de dos o més residus, contribueix a superar alguns problemes de la mono-digestió i a augmentar la producció d’energia. Aquesta Tesi Doctoral avalua diferents processos que s’inclouen en el concepte de biorefineria d’algues: utilització de les algues per a la degradació de microcontaminants, producció d’energia per a la metanització de les algues, co-digestió amb altres residus orgànics propers, i utilització dels fluxos de residus generats com a fertilitzants. Primer, s’ha estudiat la degradació individual de tres pesticides polars i tres hidrofòbics per un cultiu mixt de microalgues i altres microorganismes. Els estudis s’han portat a terme en diferents condicions experimentals per a determinar els principals mecanismes de degradació. La biodegradació i fotodegradació contribueixen a l’eliminació del propanil (100%), de l’acetamiprid (100%), de l’oxadiazon (55%), del clorpirifos (35%) i de la cipermetrina (14%), mentre que més del 60% del clorpirifos i la cipermetrina s’eliminen per biosorpció. S’han identificat els productes de transformació del clorpirifos, l’acetamiprid i el propanil per les microalgues actives. Després, s’ha avaluat el comportament d’un fotobioreactor pilot, operat a un temps de residència hidràulic de 8 dies, en el tractament d’una aigua residual sintètica amb una mescla de pesticides. S’ha avaluat la capacitat de degradació del sistema per l’eliminació de nutrients i pesticides, i s’han detectat alguns productes de degradació. Els rendiments d’eliminació de l’nitrat i el fosfat han estat del 24 i 94%, respectivament. El propanil i l’acetamiprid varen ser eliminats molt eficientment (99 i 71%, respectivament) principalment per biodegradació. A més, el procés de metanització de la biomassa algal no es va veure inhibit pels pesticides adsorbits a la biomassa. S’han avaluat diferents pretractaments suaus i de baix consum energètic per incrementar la solubilitat i digestibilitat de la biomassa algal. Prèviament es recullen les microalgues per diferents tècniques: sedimentació natural, coagulació-floculació, i modificació del pH. Els resultats dels pretractaments tèrmics a baixa temperatura i pretractaments enzimàtics indiquen que per a la biomassa algal, l’increment de solubilitat porta a un augment del rendiment en la producció de biogàs. No obstant, per a la co-digestió de llots activats i biomassa algal, encara que un pretractament augmenti la solubilitat, el rendiment de producció de biogàs no augmenta. S’avalua finalment un cas estudi real per a integrar un sistema basat en microalgues en una planta de tractament d’aigües residuals d’una empresa vinícola, perseguint una proposta circular de recuperació de nutrients i energia de l’aiguaresidual i dels llots. El tractament terciari de l’aigua residual per les microalgues elimina eficientment l’amoni (97%) i el fosfat (93%). La biomassa algal produïda es va co-digerir amb llots en un reactor pilot de 50 L obtenint un rendiment de metà de 225.8 NL CH4 kg SV-1, i els digestats de la mono i co-digestió, i la biomassa algal assecada van millorar el creixement dels cultius en utilitzar-los com a fertilitzants.
Las tecnologías basadas en microalgas ofrecen una solución prometedora para cambiar el foco desde el tratamiento de residuos y aguas hacia la recuperación de energía y recursos. Las microalgas eliminan nutrientes de las aguas residuales y producen oxígeno para que las bacterias biodegraden la materia orgánica. Estos procesos se implementaron con éxito en el tratamiento de aguas residuales urbanas, pero en las ciudades cada vez más industrializadas y en los entornos agrícolas, el reto es determinar si estos sistemas pueden degradar contaminantes orgánicos como los pesticidas. La biomasa algal puede valorizarse para producir biocombustibles y otros bio-productos. La digestión anaeróbica es una tecnología consolidada para convertir residuos orgánicos en energía renovable (biogás). La co-digestión anaerobia de dos o más residuos contribuye a superar los inconvenientes de la mono-digestión e impulsa la producción de energía. Esta tesis evalúa diferentes procesos incluidos en el concepto de biorrefinería de microalgas: utilización de las algas para degradar micro-contaminantes, producción de energía mediante la digestión anaerobia de algas, la co-digestión con otros residuos cercanos, y la utilización de flujos de residuos como fertilizantes. Primero, se estudió la degradación individual de tres pesticidas polares y tres pesticidas hidrofóbicos mediante un cultivo de microalgas y otros microorganismos. Se estudiaron diferentes condiciones para determinar los mecanismos de degradación. La biodegradación y la foto-degradación contribuyeron a la eliminación del propanil (100%), acetamiprid (100%), oxadiazon (55%), clorpirifós (35%) y la cipermetrina (14%). Más del 60% del clorpirifós y la cipermetrina se eliminaron por bio-sorción. Se identificaron los productos de transformación generados por las microalgas para el clorpirifós, el acetamiprid y el propanil. Se evaluó el rendimiento de un fotobiorreactor piloto de exterior operado a un TRH de 8 días en el tratamiento de aguas residuales sintéticas conteniendo una mezcla de pesticidas. Se evaluó la capacidad de degradación cuantificando la eliminación de nutrientes y pesticidas, y se detectaron los productos de transformación. Las eficiencias de eliminación de nitratos and ortofosfato fueron del 24 y 94%, respectivamente. El propanil y el acetamiprid se eliminaron eficazmente (99 y 71%, respectivamente), principalmente por biodegradación. La digestión anaeróbica de las algas no fue inhibida por los pesticidas retenidos. Para mejorar la solubilidad y la digestibilidad anaeróbica de la biomasa algal, se evaluaron diferentes pretratamientos energéticamente eficientes. Previamente, se estudió la cosecha de las microalgas mediante técnicas de bajo coste: sedimentación natural, coagulación-floculación y floculación inducida por pH. Los pretratamientos se aplicaron antes de la co-digestión anaeróbica de las microalgas con lodos activados. Se evaluó el efecto de los pretratamientos térmicos a baja temperatura para las mezclas de microalgas y lodos, y se investigó el efecto de los pretratamientos enzimáticos en la solubilización de la pared celular de las microalgas. En ambos casos, se comprobó el efecto del pretratamiento en el rendimiento de biogás. La solubilidad de las algas aumentó, incrementando el rendimiento de metano. Sin embargo, en la co-digestión de lodos y algas, incluso cuando la solubilidad aumentó tras el pretratamiento, la producción de biogás no incrementó. Además, esta tesis evalúa un caso de estudio para la integración de un sistema basado en microalgas en la planta de tratamiento de aguas residuales de una empresa vinícola para aplicar un enfoque circular en la recuperación de nutrientes y energía de sus aguas residuales y lodos. El tratamiento terciario de las aguas residuales mediante microalgas eliminó eficazmente el amonio (97%) y el ortofosfato (93%). La biomasa algal fue co-digerida en un digestor anaerobio piloto de 50 L con lodos produciendo 225.8 NL CH4 kg VS-1. Los digestatos de mono-digestión y co-digestión y la biomasa seca de algas mejoraron la acumulación de biomasa vegetal al usarlos como fertilizantes.
Microalgae-based technologies offer a promising solution to shift the focus from wastes and wastewater treatment, toward energy and resource recovery. In these systems, microalgae remove nutrients from wastewater and produce oxygen useful for bacteria to biodegrade organic matter. This has been fully demonstrated in urban wastewater treatment, but in increasingly industrialised cities and agricultural environments, the challenge is to determine if microalgae-based systems can degrade organic micropollutants such as pesticides. Microalgae biomass can be further valorised for the production of biofuels and valuable bioproducts. Anaerobic digestion is one of the most established technologies to convert organic wastes into renewable energy in the form of biogas. Another opportunity is the simultaneous anaerobic co-digestion of two or more bio-wastes, contributing to overcome the drawbacks of mono-digestion and boosting energy production in anaerobic digestion plants. Nonetheless, microalgae anaerobic digestion is generally hindered by the recalcitrancy of their cell walls, which lead to low methane potential. The present thesis assesses different processes included in the microalgal biorefinery concept: utilisation of algae for micropollutant degradation, energy production by algal anaerobic digestion, co-digestion with other nearby wastes, and utilisation of waste streams as fertilizers. First, it was studied the individual degradation of three polar and three hydrophobic pesticides frequently found in surface waters by a mixed-microalgae culture. Different conditions were studied to determine the main degradation mechanisms. Biodegradation plus photodegradation contributed to the removal of propanil (100%), acetamiprid (100%), oxadiazon (55%), chlorpyrifos (35%), and cypermethrin (14%) while more than 60% of chlorpyrifos and cypermethrin were removed by bio-sorption. Transformation products generated by the active microalgae were identified for chlorpyrifos, acetamiprid, and propanil. The performance of an outdoor pilot-photobioreactor operated at a HRT of 8 days in the treatment of synthetic wastewater containing a mixture of selected pesticides was assessed. During the steady-state, degradation capacity was evaluated by quantifying nutrients and pesticides removal, and transformation products were detected. Nitrate and ortophosphate removal efficiencies were 24 and 94%, respectively. Propanil and acetamiprid were effectively removed (99 and 71%, respectively) mainly by algal-mediated biodegradation as confirmed by the transformation products detected. The anaerobic digestion of the algal biomass was not inhibited by the retained pesticides. To enhance the solubility and the anaerobic digestibility of algal biomass, different mild pretreatments were assessed. Formerly, microalgal harvesting was tested by different cost-effective techniques: sedimentation, coagulation-flocculation, and pH-induced flocculation. The pretreatments were applied before the anaerobic co-digestion of microalgae with sludge. The effect of thermal pretreatments at low temperature were evaluated for microalgae and sludge mixtures. Additionally, the effect of enzymatic pretreatments on microalgae cell wall solubilisation was investigated. In both cases, the effect of the pretreatment in the biogas yield was tested. Results indicate that algal biomass solubility increased and led to a higher methane yield. Nonetheless, in the co-digestion of sludge and algal biomass, even when biomass solubility was enhanced after the pretreatment, biogas production did not increase. Furthermore, this thesis assesses a case study for the integration of a microalgae-based system into the industrial wastewater treatment plant of a winery company looking for a circular approach for nutrients and bioenergy recovery from wastewater and sludge. Tertiary wastewater treatment by microalgae efficiently removed ammonium (97%) and phosphate (93%). Algal biomass was co-digested in a 50 L pilot anaerobic digester with sludge obtaining a yield of 225.8 NL CH4 kg VS-1. The digester was operated in SBR mode showing adaptations to substrate variability over time. The valorisation of the generated bio-wastes for fertilization indicate that mono- and co-digestion digestates and dry algal biomass improved plant biomass accumulation (growth indexes of 163, 155 and 121% relative to those of the control -commercial amendment-).
Universitat Autònoma de Barcelona. Programa de Doctorat en Ciència i Tecnologia Ambientals

Le biotecnologie microalgali hanno ricevuto sempre più attenzione negli ultimi anni come metodo alternativo ai convenzionali processi di trattamento delle acque reflue e come possibile soluzione per la cattura dell’anidride carbonica (CO2). A ciò si aggiunge la possibilità di valorizzare ulteriormente la biomassa microalgale prodotta. Sebbene si tratta di una tecnologia attraente, prima della sua applicazione a larga scala, bisogna risolvere una serie di ostacoli. La principale finalità di questo lavoro consiste nello studio di alcuni aspetti critici legati alla produzione sostenibile di microalghe, relativi a fattori biotici (luce, carico di nutrienti), utilizzo della CO2, produzione di lipidi e raccolta della biomassa. Una policoltura algale, costituita principalmente da cianobatteri e microalghe (Chlorella sp., Scenedesmus sp.) è stata coltivata in un refluo urbano non pretrattato in fotobioreattori sottoposti a diverse luminosità e carico di nutrienti. Lo studio ha portato ad identificare le migliori condizioni per la produzione di biomassa e l’accumulo di lipidi, nel minore carico di nutrienti (~ 10 mg NH4+/L, ~ 6.5 mg PO43-/L) e nella più alta luminosità (100 µmol s-1m-2). Il maggiore recupero della biomassa, corrispondente al 72% è stato riscontrato per la più bassa luminosità testata (20 µmol s-1m-2) ed il più basso carico di nutrienti al termine del periodo di coltivazione. La stessa policoltura è stata coltivata in un sistema aperto (vasca pilota da 200 L), in acqua reflua urbana, al fine di analizzarne la potenzialità di catturare CO2, applicando diversi flussi di gas in ingresso (0.2, 0.4, 1 L/min). La crescita della biomassa, l’assorbimento di carbonio inorganico e di nutrienti sono stati analizzati durante la fase di avviamento della coltivazione ed in condizioni di alimentazione in semi-continuo. I più bassi flussi di gas hanno favorito la fissazione della CO2 biodisponibile, mentre i flussi più alti di gas hanno favorito l’assorbimento totale della CO2 nel sistema aperto, in corrispondenza della maggiore produttività microalgale (28.3 g d1m-2 al flusso di 1.0 L/min). Una coltivazione combinata di microalghe e lieviti è stata condotta in condizioni batch in acqua reflua urbana, nel sistema aperto, al fine di incrementare l’accumulo di lipidi totali nella biomassa. L’accrescimento dei lieviti è stato riscontrato solo nel corso dei primi giorni di coltivazione poiché limitato dalla scarsa disponibilità di substrati organici facilmente assimilabili. L’accrescimento microalgale è stato caratterizzato da tre giorni iniziali di latenza e dalla successiva crescita lineare, durante la quale le concentrazioni di azoto (N) e fosforo (P) sono state ridotta ai tassi di 2.9 mgN•L-1•d-1 e 0.96 mgP•L-1•d-1. La concentrazione di lipidi è stata monitorata durante il periodo di coltivazione, raggiungendo il tasso maggiore al termine del periodo di coltivazione (15% lipidi/peso secco) e risultando principalmente costituiti da acido arachidico. La bioflocculazione è stata studiata quale tecnica di raccolta delle microalghe analizzando le interazioni con cianobatteri filamentosi. Detti cianobatteri sono stati ottenuti dalla coltivazione della policoltura algale in specifiche condizioni di luce, temperatura, liquido e tecnica di coltura. Microalghe e cianobatteri sono stati coltivati in liquido sintetico ed in acqua reflua urbana pre-filtrata. I cianobatteri hanno mostrato una naturale tendenza flocculante favorendo l’agglomerazione nei fiocchi di parte delle microalghe in sospensione. La tendenza flocculante dei cianobatteri è stata, successivamente, analizzata utilizzando due sistemi di coltura (bolle d’aria e momento rotante) e diverse concentrazioni iniziali di inoculo. I risultati hanno mostrato una migliore capacità flocculante nel caso di miscelazione mediante bolle d’aria e con più alte concentrazioni iniziali di biomassa. Infine, la migliore condizione per la sedimentazione spontanea della biomassa è stata ottenuta al termine della fase di crescita esponenziale.
Microalgal biotechnology has received more and more attention in recent years as an alternative method of conventional wastewater treatment process and as possible solution for carbon dioxide capture. Moreover, the algal biomass generated during wastewater treatment is regarded as exploitable resource. Although this technology is attractive, a number of obstacles need to be solved before large-scale applications. The main purpose of this work is to study some critical aspects linked to the sustainable microalgal production chain, such as biotic factors (light, nutrients supply), carbon dioxide utilization, lipids production and biomass harvest. A wastewater-autochthonous algal culture was used to treat raw urban wastewater in closed photobioreactors under different light intensities and nutrients supply. The best conditions for both biomass production and lipids accumulation resulted in low nutrients supply (~ 10 mg NH4+/L, ~ 6.5 mg PO43-/L) and high light intensity (100 µmol s-1m-2). The biomass autoflocculation was investigated at the end of the cultivation period, corresponding to the high pH values of the cultivation media. The highest biomass recovery of 72% was estimated for the lowest light intensity (20 µmol s-1m-2) and nutrients supply conditions. The same wastewater-autochthonous algal culture was further cultivated in an open system (200 L pilot-scale raceway pond), using urban wastewater as growth medium, to analyse its carbon dioxide capture potential, applying different gas input flowrates (0.2, 0.4 and 1.0 L/min). Biomass growth, inorganic carbon and nutrients absorption were also studied during the cultivation start-up and its semi-continuous feeding conditions. Low gas flowrates favoured the fixation of bio-available CO2, while higher gas flowrates favoured the CO2 absorption in the open system, corresponding also the highest microalgal productivity (28.3 g d-1m-2 at the gas flowrate of 1.0 L/min). The combined cultivation of microalgae and yeast was conducted in batch conditions and in the open system, with the final purpose of increase the total lipid concentration of the produced biomass. Urban wastewater was used as growth medium. Yeast growth was monitored only during the first days of the cultivation because of the low availability of easy assimilated organic substrates in the medium. Microalgae growth showed a 3 days long initial lag phase and a subsequent linear growth, during which nutrients were completely depleted with 2.9 mgN•L-1•d-1and 0.96 mgP•L-1•d-1 of removal rates. The cultivation induced a natural bactericidal and antifungal action at the end of the cultivation period (14 days). The highest lipids content was measured at the end of the cultivation (15% lipids/dry weight) and resulted mainly composed by arachidic acid. Bioflocculation was studied as harvesting technique since it is low cost and not toxic for the biomass. First, microalgae bioflocculation was studied through their interaction with filamentous cyanobacteria. The filamentous cyanobacteria were obtained by the cultivation of the wastewater-autochthonous algal culture in specific condition of light, temperature, growth media and cultivation mode. Microlagae and cyanobacteria were cultivated in synthetic media and in pre-filtered urban wastewater. Natural flocculation occurred for cyanobacteria and enhanced the microalgae harvesting which resulted trapped in cyanobacteria mats; anyway, the suspended microalgae limited the clarification of the growth media. Finally, the natural cyanobacteria flocculation-tendency was further investigated applying two different mixing systems (air bubbles and shaking moment) and different initial biomass concentrations. Results showed a better flocculation performance in case of air bubbles mixing and with high initial biomass concentration. Moreover, the best condition for the natural biomass settling corresponded to the end of the biomass exponential growth state.

Cette thèse s'attache à la maximisation de la consommation du dioxyde de carbone par les microalgues. En effet, suite aux différentes problématiques environnementales actuelles liées principalement aux émissions importantes de gaz à effet de serre et notamment le CO2, il a été démontré que les microalgues jouent un rôle très prometteur pour la bio-fixation du CO2. Dans cette optique, nous nous intéressons à la mise en place d'une loi de commande robuste permettant de garantir des conditions opératoires optimales pour une culture de la microalgue Chlorella vulgaris dans un photobioréacteur instrumenté. Cette thèse repose sur trois axes principaux. Le premier porte sur la modélisation de la croissance de l'espèce algale choisie à partir d'un modèle mathématique traduisant l'influence de la lumière et de la concentration en carbone inorganique total. En vue de la commande, le deuxième axe est consacré à l'estimation de la concentration cellulaire à partir des mesures disponibles en temps réel du dioxyde de carbone dissous. Trois types d'observateurs ont été étudiés et comparés : filtre de Kalman étendu, observateur asymptotique et observateur par intervalles. Le dernier axe concerne l'implantation d'une loi de commande prédictive non-linéaire couplée à une stratégie d'estimation pour la régulation de la concentration cellulaire autour d'une valeur maximisant la consommation du CO2. Les performances et la robustesse de cette commande ont été validées en simulation et expérimentalement sur un photobioréacteur instrumenté à l'échelle de laboratoire. Cette thèse est une étude préliminaire pour la mise en œuvre de la maximisation de la fixation du dioxyde de carbone par les microalgues.

Les conditions de culture de microalgues autotrophes en système ouvert associant microalgues / bactéries ont été étudiées au cours de ce travail de thèse. L'objectif était de développer un procédé de valorisation des nutriments (N, P) contenus dans la phase liquide des digestats issus de méthanisation agricole. Dans un premier temps, une synthèse sur les filières de méthanisation suivi d'un état de l'art sur les microalgues et leurs conditions de culture ont permis de mettre en évidence les principaux paramètres d'influence spécifiques à l'influent étudié, tels que la coloration, et les interactions avec les processus de nitrification/dénitrification. Ainsi, dans le but de mieux comprendre les mécanismes et d'évaluer les impacts des paramètres principaux, un pilote de laboratoire composé de 6 réacteurs de 2,5 litres a été conçu et des analyses spécifiques ont été développées au laboratoire. A partir de ces outils, l'effet de la couleur et de la lumière sur la pénétration de la lumière et sur la croissance algale a été quantifié. Ensuite, l'influence du ratio N/P du milieu a été testée, ce qui a permis de mettre en exergue le stockage du phosphore par les microalgues, leur permettant de continuer leur croissance lorsque le phosphore du milieu est épuisé. Par la suite, le transfert du dioxyde de carbone et son impact sur la croissance des microalgues ont été étudiés. La productivité algale est fonction de la quantité de CO2 fournie à la culture et chute à 0 sans injection. Enfin, l'étude du temps de séjour des solides et de leur fréquence d'extraction a révélé que la nitrification-dénitrification est un mécanisme important d'élimination de l'azote dans une culture algale en continu et en système ouvert. Il peut même s'avérer prédominant par rapport à l'assimilation de l'azote par les microalgues dans certaines conditions. La proportion de chacun de ces processus peut néanmoins être contrôlée par ces paramètres. Ces expérimentations ont par ailleurs permis de mieux comprendre les interactions entre microalgues et bactéries nitrifiantes ainsi que la prédominance des genres d'algues en fonction des conditions de culture. Les microalgues sont de meilleures compétitrices sur le phosphore que les bactéries nitrifiantes. De plus, lorsque le phosphore n'est pas limitant, la nitrification est réduite en proportion de la productivité algale. En cas de limitation en phosphore et avec une faible lumière disponible, les genres d'algues qui se sont montrés dominants sont Scenedesmus sp. et Chlorella sp. Respectivement. Les essais expérimentaux ont été complétés par le développement ou l'adaptation de modèles biocinétiques capables de représenter la croissance algale et l'épuration assez fidèlement. A partir de cette modélisation, différentes configurations ont été simulées pour dimensionner un lagunage algal à haut rendement et ainsi mieux comprendre et apprécier la faisabilité d'une culture algale pour extraire les nutriments des digestats
The culture conditions of autotrophic microalgae in open system associating microalgae/bacteria were studied in this thesis. The objective was to develop a process to valorize nutrients (N, P) contained in the liquid phase of digestate coming from agricultural methanization. First, a synthesis of anaerobic digestion process followed by a state of art on microalgae and their culture conditions allowed to highlight the main parameters specific to the studied influent, such as coloration, and the interactions with nitrification-denitrification processes. To better understand the mechanisms and study the impact of the main parameters, a laboratory-scale pilot composed of six 2.5L-reactors was designed and specific analyses were developed at the laboratory. With the help of those tools, effects of color and light on light penetration and on microalgae growth were quantified. Then, the study of the N:P ratio of the medium allowed to highlight the phosphorus storage by microalgae, allowing them to continue their growth while the phosphorus of the medium was depleted. Thereafter, the carbon dioxide transfer and its impact on microalgae growth were studied. The algal productivity is a function of the quantity of provided CO2 into the culture and fall to zero without injection. Finally, the study of solid retention time and extraction rate revealed that nitrification-denitrification is an important mechanism for nitrogen removal in a continuous algae culture in open system. This mechanism may even be predominant compared to nitrogen assimilation by microalgae under certain conditions. The proportion of each of these processes may still be controlled by these parameters. These experiments have also provided insight into the interactions between microalgae and nitrifying bacteria and the predominance of algae genera depending on culture conditions. Microalgae are better competitors on phosphorus than nitrifying bacteria. Furthermore, in non-limiting phosphorus conditions, nitrification is reduced in proportion to algal productivity. Scenedesmus and Chlorella proved to be dominant respectively when phosphorus and light are limiting. The experimental trials were completed by the development or the adaptation of biokinetic models able to represent quite accurately microalgae growth and nitrogen removal. From this model, different configurations were simulated to design high rate algal pond and assess the feasibility of the algal culture to extract nutrients from digestate

Ce travail s’oriente vers la valorisation du traitement d’eaux usées à partir de piles à combustibles microbiennes (PCM) benthiques pour la production d’électricité. Cette technologie permet la production d’électricité à partir de micro-organismes électro-actifs (EA) et d’un substrat carboné qui peut être de l’eau usée.Quatre types d’eaux usées issues de l’activité anthropique sont sélectionnés. La présence de micro-organismes EA est mise en évidence par 2 méthodes électrochimiques. En condition réelle, le milieu lagunaire présente les meilleures performances électriques (6,6 mW/m²). Celui-ci propose l’environnement le plus favorable à l’installation dePCM benthiques in-situ. Les résultats montrent une forte influence des micro-algues sur l’activité des biofilms EA. Avec un cycle jour/nuit, cette production varie en suivant les cycles d’éclairage. Les micro-algues apportent l’oxygène nécessaire aux réactions cathodiques. Les PCM améliorent également la consommation de polluants du milieu cathodique.L’alimentation de petits dispositifs tels que des capteurs passe obligatoirement par une augmentation de la tension délivrée par les biopiles. Différentes techniques d’élévation de la tension (mise en série et en parallèle de plusieurs piles, convertisseurs DC/DC) sont analysées. Un capteur de température et d’humidité a fonctionné durant plus de 15 h directement alimenté par une de nos biopiles benthiques avec une puissance de 328 µW. Sa tension de sortie est augmentée par un convertisseur de type Flyback, passant de 560 mV à plus de 5,5 V. L’utilisation de PCM in-situ dans la lagune peut constituer une alternative à la production électrique et au traitement des eaux usées
The work described in this document is oriented to enhancing the treatment of wastewater from benthic microbial fuel cell (BMFC) for electricity production. This technology allows the production of electricity from electro-active (EA) microorganisms and carbonated substrate which may be the wastewater.Four types of wastewater from human activity are selected. The presence of EA microorganisms is highlighted by two electrochemical methods. In real conditions, the lagoon environment has the best electrical performance (6.6 mW/m²).The lagoon environment offers the most favorable environment for installation BMFC in-situ. The results show a strong influence of microalgae on the EA biofilms activities and thus on the production of electricity. In lagoon conditions, with a day/night cycle, this production varies according to the lighting cycles. Microalgae bring oxygen necessary for cathode reactions at lower cost. BMFC also improve the consumption of pollutants including organics.Electrical supply by small devices such as sensors necessarily requires an increase of the voltage delivered by BMFC. The different voltage boosting techniques such as series and parallel connections of several units or the use of DC/DC converters are performed and analyzed. A temperature and humidity sensor worked for more than fifteen hours directly powered by a BMFC with a power of 328 µW. Its output voltage is increased by a flyback type DC/DC converter, from 560 mV to more than 5.5 V. The use of PCM in-situ in the lagoon can be an alternative to the power generation and the treatment of wastewater

Les lagunes côtières présentent une forte importance écologique, économique et sociale. Toutefois, elles sont particulièrement vulnérables face aux pressions anthropiques et aux changements climatiques, notamment en région méditerranéenne. La conservation des lagunes est donc fondamentale pour la protection des systèmes littoraux et le bien-être des populations humaines. Cette thèse vise à apporter un soutien aux politiques publiques pour la restauration et la conservation des lagunes côtières, mais également à rechercher de potentielles valorisations des ressources. Les travaux ambitionnent d’approfondir les connaissances sur les trajectoires d’évolution des communautés phytoplanctoniques et des lagunes côtières du littoral corse, (i) en questionnant l’évolution des variations saisonnières face aux paramètres abiotiques, mais également l’impact des variations de salinité, notamment dans le cadre du changement climatique, sur de grandes et/ou de petites lagunes et (ii) en testant différentes approches intégrées avec la prise en compte de l’impact de l’homme, du bassin versant jusqu’à la mer.Les communautés phytoplanctoniques de six lagunes du littoral corse (Diana, Urbino, Biguglia, Arasu, Santa Giulia, Balistra) sont étudiées dans ce cadre. Les analyses sur le long terme grâce aux données historiques disponibles, les suivis in situ et les expérimentations réalisées ont permis d’identifier des dynamiques saisonnières marquées des communautés phytoplanctoniques et des éléments centraux pour la gestion des milieux lagunaires. La tendance vers une dominance des dinoflagellés, l’émergence d’espèces tolérant le stress (e.g. salinités extrêmes), parfois potentiellement toxiques, l’augmentation des blooms phytoplanctoniques ainsi que des modifications des cycles saisonniers ont été mis en évidence sur des lagunes de grandes et de petites tailles. Ces phénomènes sont liés principalement à des impacts d’origine anthropique (pollution, rejets urbains, usage de l’eau, tourisme…), des altérations hydrologiques engendrées par des interventions humaines, et le changement climatique.L’étude d’autres compartiments biotiques et abiotiques de l’écosystème, comme l’invasion biologique, la production halieutique ou le fonctionnement hydrogéologique, a confirmé la nécessité d’appliquer une approche écosystémique, du bassin versant jusqu’à la mer, pour comprendre le fonctionnement global du système. La prise en compte de l’Homme dans l’étude des trajectoires écologiques a été aussi mise en évidence, soulignant que les lagunes doivent être considérées comme des socio-écosystèmes. Cette vision holistique est fondamentale pour envisager une gestion optimale intégrée de la complexité du système.Cette thèse apporte de plus un regard nouveau sur les lagunes de petites surfaces à l’échelle du littoral méditerranéen qui sont très réactives aux changements et qui peuvent être considérées comme des sentinelles de l’évolution climatique.Parallèlement, l‘étude d’une souche de diatomée issue de l’étang de Diana a démontré des caractéristiques écophysiologiques et chimiques prometteuse pour de potentielles applications biotechnologiques dans le domaine de l’aquaculture, en raison de son origine lagunaire.L’ensemble de ces résultats sur les trajectoires d’évolution passées et futures a permis de marquer la complexité et la vulnérabilité des lagunes côtières (et celles de petites surfaces en particulier) face aux menaces croissantes et des interrogations sur leur avenir. Ce travail fournit donc des éléments d’appui pour la gestion des lagunes et de valorisation des ressources liées à ces milieux, en proposant une gestion intégrée et interdisciplinaire pour une conservation durable de ces écosystèmes et des services fournis, notamment dans le cadre du changement climatique
Coastal lagoons are of high ecological, economic and social importance. Nevertheless, they are particularly vulnerable to anthropogenic pressure and climate change, especially in the Mediterranean region. Lagoons’ conservation is hence fundamental for the protection of littoral systems and the well-being of human populations. This thesis aims to provide support for public policies for the restoration and conservation of coastal lagoons, but also to look for potential resources’ valorisation. The works aim to deepen knowledge on the evolution trajectories of phytoplankton communities and coastal lagoons of the Corsican coast, (i) by questioning the evolutions of seasonal variations linked to abiotic factors, but also the impact of salinity variations, particularly in the context of climate change, on large and/or small lagoons, and (ii) by testing different integrated approaches taking into account the human impact, from the watershed to the sea.Phytoplankton communities of six Corsican lagoons (Diana, Urbino, Biguglia, Arasu, Santa Giulia, Balistra) are studied in this framework. Analysis of long term historical datasets available, in situ monitoring and experimental essays performed allowed the identification of marked seasonal dynamics of phytoplankton communities and central elements for coastal lagoons’ management. The trend towards the dominance of dinoflagellates, the emergence of stress-tolerant (e.g. extreme salinities), sometimes potentially toxic, the increase in phytoplankton blooms as well as changes in the seasonal cycles have been highlighted in large and small sized lagoons. These phenomena are mainly linked to anthropogenic impacts (pollution, urban wastewater, water use, tourism…), hydrogeological alterations caused by human interventions, and climate change.The study of other biotic and abiotic compartments of the ecosystem, like biological invasion, fish production or hydrogeological functioning, has confirmed the need to apply an ecosystem-based approach, from the watershed to the sea, in order to understand the overall functioning of the system. The consideration of Humans in the study of ecological trajectories has also been highlighted, emphasizing that lagoons should be considered as social-ecological systems. This holistic vision is fundamental to consider an optimal integrated management of the complexity of the system.Moreover, this thesis provides a new perspective on small surfaced lagoons on the Mediterranean coast scale, which are very reactive to change and can thus be considered as sentinels of climate change.At the same time, the study of a diatom strain from the Diana lagoon has demonstrated promising ecophysiological and chemical characteristics for potential biotechnological applications in the aquaculture domain, due to its lagoon origin.The overall results on the past and future evolution trajectories have highlighted the complexity and vulnerability of coastal lagoons (and those of small surface areas in particular) in the face of growing threats and some questions about their future. This work provides hence some supporting elements for the lagoon management and the valorisation of resources linked to these environments, by proposing an integrated and interdisciplinary management for the sustainable conservation of these ecosystems and of the services provided, particularly in the climate change context

La bioraffinerie est similaire à la méthodologie utilisée en industrie pétrochimique qui consiste à séparer les constituants d’une biomasse pour les convertir en différents produits à forte valeur ajoutée. La microalgue Porphyridium cruentum est bien connue dans la littérature pour sa production de nombreux métabolites valorisables tels que des pigments (B-Phycoerythrine, zéaxanthine) ; des acides gras oméga 3 et oméga 6, des exopolysaccharides (EPS). A ce jour, il n’existe pas de schéma de procédés intégrés visant à aboutir à la valorisation totale de cette biomasse. C’est donc avec une approche de bioraffinerie, visant à rendre viable la production de microaglues, que le travail présenté ici a été réalisé. Un schéma de procédé global, constitué de 4 étapes, culture et récolte des microalgues, destruction cellulaire, fractionnement des différentes familles de molécules et purification, a été mis en place. La phase de culture a permis d’atteindre une concentration en biomasse de 2,7 g. L-1. Différentes méthodes de destruction cellulaire ont été testées telles que la congélation/décongélation, le broyage haute pression. Leur impact sur les différentes fractions extraites a été étudié. Un procédé d’extraction sélective en deux étapes, permettant d’aboutir à l’obtention d’un extrait prépurifié en B-phycoérythrine, a été développé. La purification de la B-phycoérythrine par deux méthodes, précipitation sélective et filtration tangentielle sur membrane, a été réalisée. De hauts degrés de pureté (IP = 3) ont été atteints par filtration sur membrane en polyethersulfone (30 kDa). 3 protocoles de valorisation de la biomasse dans son ensemble ont également été développés
Biorefinery is the same methodology used in oil industry to separate each component of a biomass and to transform them into high value products. The microalga Porphyridium curentum is well referenced in the literature as a producer of many metabolites of interest like pigments (B-Phycoerythrin, zeaxanthin), ω3 and ω6 fatty acids and exopolysaccharides (EPS). We propose to apply the concept of biorefinery to P. Cruentum in order to produce different extracts of interest and so to make the biomass production profitable. We experimentally developed a process to produce and to separate the different fractions of P. Cruentum made of 4 main steps: cultivation and harvesting of the algae, cell disruption, separation of each biochemical family and purification of the latter. The optimization of culture conditions leads to a production of microalgae at the concentration of 2. 7g. L-1. Different cell destruction techniques have been tested such as high pressure cell disruption and freezing/thawing. Their impact on the molecules extracted has also been studied. A selective two-steps process has been developed to obtain pre-purified B-phycoerythrin extract. The purification of the latter has been tested by two different methods: the selective precipitation using ammonium sulfate and the tangential filtration on membrane. High purity levels (IP=3) have been reached using a filtration on polyethersulfone membrane (30kDa). 3 protocols have been developed and tested to promote the whole biomass

The development of renewable liquid fuels is essential for reducing the impact of the transport sector on the environment. To achieve this, photosynthetic microalgae offer a credible source of biomass that could potentially meet the volume demand of this sector. While much research effort has been invested in developing microalgal biodiesel, an economic process remains elusive. A more promising route is the thermochemical conversion of whole algal biomass, especially by hydrothermal liquefaction. This creates a viscous bio-oil that can be further upgraded into suitable hydrocarbon fuels. Although a host of research challenges remain, these processes utilise the whole biomass and remove the costly de-watering and extraction stages. As such, the thermochemical transformation of algal biomass offers a credible route to an affordable renewable transport fuel. This chapter reviews the chemical processing considerations of producing algal biodiesel and fuels from the thermochemical valorisation of algal biomass and discusses the remaining research challenges in this area.