Orientador: Telma Teixeira FrancoTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia QuimicaResumo: A conversão fotossintética de dióxido de carbono em fotobiorreatores foi investigada com o propósito do desenvolvimento de um sistema biológico para o seqüestro de carbono. O processo utilizado consiste na transferência de dióxido de carbono gasoso para a fase líquida de um reator, no qual este composto é convertido em produtos do metabolismo fotossintético pela atividade de microalgas. Em face disto, o trabalho teve por objetivos: (1) avaliar o cultivo fotossintético da microalga SKDQRWKHFHPLFURVFRSLFD1lJHOLemdiferentescondic\co~esdetemperatura,intensidadeluminosaeconcentrac\ca~odedioˊxidodecarbono;(2)avaliaracineˊticadeabsorc\ca~o/dessorc\ca~odedioˊxidodecarbonoemfotobiorreatores;(3)definirascondic\co~esoperacionaisapropriadasparaaremoc\ca~obioloˊgicadecarbono;(4)avaliarosefeitosdosciclosdeluminosidadenafixac\ca~odedioˊxidodecarbonoe(5)estudardiferentesconfigurac\co~esemodosdeoperac\ca~odefotobiorreatorespararemoc\ca~odeCO2.Acapacidadedesequ¨estrodecarbonodosistemafoiconsideradaatraveˊsdeanaˊlisesdosperfisdeCO2livrenafaselıˊquidadosistema,medidasdasconcentrac\co~esdafasegasosaeconversa~oestequiomeˊtricaembiomassa.Osresultadosobtidosdemonstraramaimporta^nciadospara^metrosoperacionaisavaliadosnafixac\ca~odecarbonoembiomassa,bemcomonaremoc\ca~odeglobaldeCO2.Ousodametodologiadesuperfıˊciederespostafoiadequadanaotimizac\ca~odoprocesso,aqualresultouemumacreˊscimosuperiora58SKDQRWKHFH_PLFURVFRSLFD_1lJHOL under different conditions of temperature, light intensity and carbon dioxide concentration; (2) evaluate the absorption/desorption kinetics of carbon dioxide in photobioreactors; (3) define the appropriate operational conditions for the biological removal of carbon; (4) evaluate the effects of light cycles on the fixation of carbon dioxide and (5) study different configurations and operational modes of photobioreactors for the removal of CO2. The carbon sequestering capacity of the system was considered from an analysis of the free CO2 profiles in the liquid phase of the system, measurements of the gas phase concentration and the stoichiometric conversion into biomass. The results obtained demonstrated the importance of the operational parameters evaluated in the fixation of carbon in biomass, as also in the overall removal of CO2. The use of response surface methodology was adequate to optimise the process, and resulted in an increase greater than 58% in the maximum cell density. The effect of the duration of the light cycle was determinant in process performance, resulting in reductions in maximum efficiency of up to 99.69%. The configurations of the reactors studied demonstrated the superior performance of airlift systems, as compared to bubble-column reactors. With respect to operational mode, the systems involving the recirculation of contaminated air were shown to be efficient in decreasing reduced amounts of carbon dioxide, although two reactors connected in series were more efficient and showed greater capacity in eliminating carbon dioxide. The current stage of development of this work is evidence of the potential for the application of this type of reactor in carbon sequestering processes, due to the elevated elimination rates. However, only the partial characterisation of the photosynthetic CO2 conversion routes was considered.DoutoradoDesenvolvimento de Processos QuímicosDoutor em Engenharia Químic