America's reliance on foreign oil has raised economic and national security issues, and in turn the U.S. has been active in reducing its dependence on foreign oil to mitigate these issues. Also, the U.S. Navy has been instrumental in driving bio-fuel research and production by setting an ambitious goal to purchase 336M gallons of bio-fuel by 2020. The production of microalgae biomass is a promising field which may be able to meet these demands. The utilization of microalgae for the production of bio-fuel requires the implementation of efficient culturing processes to maximize production and reduce costs. Therefore, three discrete rate event simulation models were developed to analyze different scaling scenarios and determine total costs associated with each scenario. Three scaling scenarios were identified by this analysis and included a stepwise, volume batching and intense culturing process. A base case and potential best case were considered in which the culturing duration, lipid content and lipid induction period were adjusted. A what-if analysis was conducted which identified and reduced capital and operational costs contributing greatly to total costs. An NPV analysis was performed for each scenario to identify the risk associated with future cash flows. The research findings indicate that the intense culturing scaling scenario yielded the greatest model throughput and least total cost for both the base case and potential best case. However, this increased productivity and cost reduction were not significantly greater than the productivity generated by the stepwise scaling scenario, suggesting that the implementation of flat plate bio-reactors in the intense culturing process may be non-advantageous given the increased operational costs of these devices. The volume batching scenario yielded the greatest total cost L^-1 of microalgae bio-oil for both, indicating an inefficient process. The scaling scenarios of the base case and potential best case yielded negative NPV's while the stepwise and intense culturing scenarios of the what-if analysis generated positive NPV's. The base case is based on current technological advances, biological limitations and costs of microalgae production therefore, a negative NPV suggests that utilizing microalgae for bio-fuel production is not an economically feasible project at this time.

A vinhaça é um dos resíduos provenientes da indústria sucroalcooleira, sendo gerados em média 12 litros do efluente para cada litro de álcool produzido. Uma elevada carga orgânica torna a vinhaça potencial agente poluidor, podendo a disposição direta no solo representar solução ambientalmente desvantajosa para este resíduo. Diante do crescimento do setor sucroalcooleiro no Brasil e da necessidade de gestão do volumoso resíduo, este estudo avaliou duas formas de tratamentos físico-químicos da vinhaça, a precipitação química e a flotação por ar dissolvido (FAD), além de um tratamento biológico através do cultivo de microalgas no efluente do sistema FAD. Avaliou-se, adicionalmente, o potencial nutritivo do sólido separado pela FAD para aplicação como suprimento em alimentação animal. A precipitação química foi estudada variando-se pH (via adição NaOH) e tempo de reação, tendo atingido eficiências de remoção de fósforo, amônia e potássio de 31,3 ± 3,4%, 7,8 ± 4,1% e 9,7 ± 0,7%, respectivamente na faixa de pH de 8,5 a 9,5. Na FAD apenas o parâmetro dosagem apresentou significância estatística na separação dos sólidos suspensos da vinhaça. A dosagem e o percentual de recirculação foram avaliados em ensaios de clarificação e de espessamento de lodo de vinhaça. Desses ensaios obteve-se que todas as faixas de dosagens e recirculações geraram eficiências de remoção de sólidos extremamente elevadas, sendo a dosagem de 20 mg/L de polímero e 13% de recirculação adotadas como vantajosas, apresentando remoção de 98,5% da turbidez. Tal configuração gerou parâmetros de projeto de flotadores de alta eficiência, com elevadas taxas de aplicação superficial. O sólido separado na FAD apresentou interessante potencial nutritivo quando comparado bromatologicamente a produtos já utilizados como alimento para bovinos. O cultivo no efluente do sistema FAD não apresentou resultados positivos mesmo na mínima concentração testada (10% v/v de vinhaça) com relação a crescimento de Chlorella vulgaris Beijerink (1890), provavelmente pela vantagem competitiva das bactérias e possível toxicidade da vinhaça em concentrações elevadas. / The stillage is a waste from the sugar and alcohol industry, which generated on average 12 liters of effluent per liter of alcohol produced. A high organic load makes the vinasse a potential pollutant agent and a direct placement in soil represent environmentally disadvantageous solution to this residue. Given the growth of this sector in Brazil and the need for this bulky waste management, this study evaluated two forms of physicochemical treatments of vinasse: chemical precipitation and dissolved air flotation (DAF), and biological treatment through microalgae cultivation in the effluent of the FAD system. Additionally, it was assessed the nutritional potential of solid separated by FAD for application as animal food supply. Chemical precipitation was studied at varying pH (by adding NaOH) and reaction time, reaching efficiencies of phosphorus, ammonia and potassium removal of 31.3 ± 3.4%, 7.8 ± 4.1% and 9.7 ± 0.7% respectively in the pH range of 8.5 to 9.5. In FAD, only the dosage parameter showed statistical significance in the separation of suspended solids of the stillage. The dosage and the percentage of recirculation were analysed in tests of clarification and thickening sludge stillage. From these tests it was found that all dosages and recirculations ranges generated extremely high solids removal efficiencies, in wich the dosage of 20 mg/ L of polymer and 13% recirculation was adopted as advantageous, with turbidity removal about of 98.5%. Such configuration generated design parameters of high efficiency floaters, with high flow rates. The separated solid in FAD showed interesting nutritional potential when bromatologically compared to products already used as food for cattle. The cultivation in the effluent of FAD system did not show positive results even at the minimum concentration tested (10% v/v vinasse with respect to growth of Chlorella vulgaris Beijerink (1890), probably due the competitive advantage of bacterias and possible toxicity of vinasse in high concentrations.

A vinhaça é um dos resíduos provenientes da indústria sucroalcooleira, sendo gerados em média 12 litros do efluente para cada litro de álcool produzido. Uma elevada carga orgânica torna a vinhaça potencial agente poluidor, podendo a disposição direta no solo representar solução ambientalmente desvantajosa para este resíduo. Diante do crescimento do setor sucroalcooleiro no Brasil e da necessidade de gestão do volumoso resíduo, este estudo avaliou duas formas de tratamentos físico-químicos da vinhaça, a precipitação química e a flotação por ar dissolvido (FAD), além de um tratamento biológico através do cultivo de microalgas no efluente do sistema FAD. Avaliou-se, adicionalmente, o potencial nutritivo do sólido separado pela FAD para aplicação como suprimento em alimentação animal. A precipitação química foi estudada variando-se pH (via adição NaOH) e tempo de reação, tendo atingido eficiências de remoção de fósforo, amônia e potássio de 31,3 ± 3,4%, 7,8 ± 4,1% e 9,7 ± 0,7%, respectivamente na faixa de pH de 8,5 a 9,5. Na FAD apenas o parâmetro dosagem apresentou significância estatística na separação dos sólidos suspensos da vinhaça. A dosagem e o percentual de recirculação foram avaliados em ensaios de clarificação e de espessamento de lodo de vinhaça. Desses ensaios obteve-se que todas as faixas de dosagens e recirculações geraram eficiências de remoção de sólidos extremamente elevadas, sendo a dosagem de 20 mg/L de polímero e 13% de recirculação adotadas como vantajosas, apresentando remoção de 98,5% da turbidez. Tal configuração gerou parâmetros de projeto de flotadores de alta eficiência, com elevadas taxas de aplicação superficial. O sólido separado na FAD apresentou interessante potencial nutritivo quando comparado bromatologicamente a produtos já utilizados como alimento para bovinos. O cultivo no efluente do sistema FAD não apresentou resultados positivos mesmo na mínima concentração testada (10% v/v de vinhaça) com relação a crescimento de Chlorella vulgaris Beijerink (1890), provavelmente pela vantagem competitiva das bactérias e possível toxicidade da vinhaça em concentrações elevadas. / The stillage is a waste from the sugar and alcohol industry, which generated on average 12 liters of effluent per liter of alcohol produced. A high organic load makes the vinasse a potential pollutant agent and a direct placement in soil represent environmentally disadvantageous solution to this residue. Given the growth of this sector in Brazil and the need for this bulky waste management, this study evaluated two forms of physicochemical treatments of vinasse: chemical precipitation and dissolved air flotation (DAF), and biological treatment through microalgae cultivation in the effluent of the FAD system. Additionally, it was assessed the nutritional potential of solid separated by FAD for application as animal food supply. Chemical precipitation was studied at varying pH (by adding NaOH) and reaction time, reaching efficiencies of phosphorus, ammonia and potassium removal of 31.3 ± 3.4%, 7.8 ± 4.1% and 9.7 ± 0.7% respectively in the pH range of 8.5 to 9.5. In FAD, only the dosage parameter showed statistical significance in the separation of suspended solids of the stillage. The dosage and the percentage of recirculation were analysed in tests of clarification and thickening sludge stillage. From these tests it was found that all dosages and recirculations ranges generated extremely high solids removal efficiencies, in wich the dosage of 20 mg/ L of polymer and 13% recirculation was adopted as advantageous, with turbidity removal about of 98.5%. Such configuration generated design parameters of high efficiency floaters, with high flow rates. The separated solid in FAD showed interesting nutritional potential when bromatologically compared to products already used as food for cattle. The cultivation in the effluent of FAD system did not show positive results even at the minimum concentration tested (10% v/v vinasse with respect to growth of Chlorella vulgaris Beijerink (1890), probably due the competitive advantage of bacterias and possible toxicity of vinasse in high concentrations.