This study aimed to evaluate the effect of variations in organic load (hydraulic retention times -HRTs: from 2 to 0.5 day) and in alkalinity (NaHCO3 from 4,000 to 1,000 mg.L -1 ) on methane production. Biomass of sewage sludge was inoculated and stabilized on 1" polypropylene rings. The rings were immersed in the liquid phase (8.41 L) of an upflow anaerobic filter reactor (12.22 L). A solution of 5 g of whole milk powder per liter was used to simulate effluent from the dairy industry. Process effectiveness was measured by chemical oxygen demand reduction, biogas production, and biogas methane content. Biogas production started at a 2-day HRT and synthetic effluent alkalinization with 4,000 mg.L -1 NaHCO3. The best operation condition was at 1-day HRT and with the addition of 4,000 mg.L -1 NaHCO3. Biogas production reached 1.5 NL of biogas per L of reactor liquid phase, with 68% of methane and a concomitant reduction in COD of 57%.
Eng Sanit Ambient | v.24 n.3 | maio/jun 2019 | 613-617 RESUMO O estudo sobre reatores anaeróbios em laboratório prioriza o controle de determinados parâmetros que são de difícil controle em campo, o que dificulta o processo de scale-up. Entre os parâmetros está a carga orgânica volumétrica (COV). No caso do dejeto suíno, esse parâmetro pode sofrer alterações diárias em função das condições climáticas, das mudanças no manejo, da alimentação dos animais, entre outros. A fim de verificar o impacto dessa variação na produtividade de biogás, foi analisado o comportamento de um reator anaeróbio de mistura completa (CSTR) em dois diferentes tempos de retenção hidráulica (TRHs) -20 e 30 dias -durante um período total de 180 dias. Os resultados demonstraram que a elevação da COV resulta em piora da eficiência de tratamento, bem como na produção de biogás. O ensaio com Efeito da variação da carga orgânica volumétrica natural na produção de biogás a partir de dejeto suíno em diferentes tempos de retenção hidráulica The effect of organic loading rate's natural variation on the biogas yields from swine manure digestion at different hydraulic retention time ABSTRACT The study of anaerobic digesters at laboratory focuses on the control of certain parameters that are not so easy to control in the field, which makes it difficult to process scale-up. One example is the Organic Loading Rate. To swine manure, this parameter can change daily due to weather conditions, management practices, feeding and others. In order to verify the impact of this fluctuation on biogas yield, the behavior of a CSTR reactor was analyzed in two different Hydraulic Retention Times (20 and 30 days) for a total period of 180 days. The result demonstrated that the increase of OLR result in a decrease of treatment efficiency as well as biogas yields. The study with HRT of 20 days had a better response to changes in organic load.
This research appraised the simultaneous biofixation of carbon dioxide (CO 2 ) and nitric oxides (NO x ) by microalgae species Chlorella vulgaris , Haematococcus pluvialis , and Scenedesmus subspicatus . The experimental design was established by five treatments with gas concentrations between control – 0.04% of CO 2 , 5 to 15% of CO 2 , and 30 to 100 ppm of NOx. Parameters such as pH, growth, productivity, lipids, protein, carbon/ nitrogen ratio, and astaxanthin were evaluated. For all species, the maximal growth was achieved with 5% of CO 2 and 30 ppm of NO x . Regarding protein content, for all the three species, better results were obtained at higher concentrations of CO 2 and NOx. These results prove the microalgae capacity for CO 2 and NO x biofixation and reuse of biomass as a source of high value-added products, such as lipids, proteins, and astaxanthin. These findings support the indication of these species for flue gas treatment process and use in biorefineries systems.
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