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- Microalgae in a global world: New solutions for old problems?Publication . Vieira De Mendonça, Henrique; Assemany, Paula; Abreu, Mariana; De Aguiar Do Couto, Eduardo; Martins Maciel, Alyne; Duarte, Renata Lopes; Santos, Marcela Granato Barbosa dosABSTRACT: The human population blast has brought several problems related with the overconsumption of a wide range of feedstocks and natural resources conducting to their risk of depletion. The consumption of fossil fuels is an example, with increasing levels of exploitation and negative impacts caused by their use. Anthropogenic activities have triggered the over accumulation of many hazardous substances and wastes which are regarded to be detrimental to life in the Earth and to the various planet ecosystems. There is an urgent need to restore natural resources and unwanted residues and wastes to levels prior the demographic explosion. Microalgal biotechnology appears to be pivotal to achieve this goal in a near future to come. This review presents the current resource problems affecting the Earth and how microalgae are expected to be an important part of the solution, discussing how the production of renewable energy from microalgae can help in an integrated way to mitigate different environmental problems. Microalgae are able to convert wastewaters, CO2 and organic residues in marketable biomass for different uses, including biofuels, converting waste in value. An inventory of current microalgal-based biorefineries in operation as well as a directory of companies, products and applications are also presented.
- Microalgae-mediated bioremediation and valorization of cattle wastewater previously digested in a hybrid anaerobic reactor using a photobioreactor: Comparison between batch and continuous operationPublication . Vieira de Mendonça, Henrique; Ometto, Jean Pierre H. Balbaud; Otenio, Marcelo Henrique; Reis, Alberto; Marques, Isabel PaulaABSTRACT: Scenedesmus obliquus (ACOI 204/07) microalgae were cultivated in cattle wastewater in vertical alveolar flat panel photobioreactors, operated in batch and continuous mode, after previous digestion in a hybrid anaerobic reactor. In batch operation, removal efficiencies ranges of 65 to 70% of COD, 98 to 99% of NH4+ and 69 to 77.5% of PO4-3 after 12 days were recorded. The corresponding figures for continuous flow were from 57 to 61% of COD, 94 to 96% of NH4+ and 65 to 70% of PO4-3 with mean hidraulic retention time of 12 days. Higher rates of CO2 fixation (327-547 mg L-1 d(-1)) and higher biomass volumetric productivity (213-358 mg L-1 d(-1)) were obtained in batch mode. This microalgae-mediated process can be considered promising for bioremediation and valorization of effluents produced by cattle breeding yielding a protein-rich microalgal biomass that could be eventually used as cattle feed.
- Combining biotechnology with circular bioeconomy: from poultry, swine, cattle, brewery, dairy and urban wastewaters to biohydrogenPublication . Ferreira, Alice; Marques, Paula; Ribeiro, Belina; Assemany, Paula; Vieira De Mendonça, Henrique; Barata, Ana; Oliveira, Ana Cristina; Reis, Alberto; Pinheiro, H. M.; Gouveia, LuisaABSTRACT: The ability of microalgae to grow in nutrient-rich environments and to accumulate nutrients from wastewaters (WW) makes them attractive for the sustainable and low-cost treatment of WW. The valuable biomass produced can be further used for the generation of bioenergy, animal feed, fertilizers, and biopolymers, among others. In this study, Scenedesmus obliquus was able to remove nutrients from different wastewaters (poultry, swine and cattle breeding, brewery and dairy industries, and urban) with removal ranges of 95-100% for nitrogen, 63-99% for phosphorus and 48-70% for chemical oxygen demand. The biomass productivity using wastewaters was higher (except for poultry) than in synthetic medium (Bristol), the highest value being obtained in brewery wastewater (1025 mg/(L.day) of freeze-dried biomass). The produced biomass contained 31-53% of proteins, 12-36% of sugars and 8-23% of lipids, regardless of the type of wastewater. The potential of the produced Scenedesmus obliquus biomass for the generation of BioH(2) through batch dark fermentation processes with Enterobacter aerogenes was evaluated. The obtained yields ranged, in mL H-2/g Volatile Solids (VS), from 50.1 for biomass from anaerobically digested cattle WW to 390 for swine WW, whereas the yield with biomass cultivated in Bristol medium was 57.6 mL H-2/gvs.