Removal of carbonaceous organic matter and nitrogen in an Aerobic-Anoxic Fix Bed Reactor (AAFBR) applied to the tertiary treatment of domestic wastewater

O presente trabalho apresenta o Reator Aeróbio-Anóxico de Leito Fixo (RAALF), constituído de duas câmaras sobrepostas, como uma alternativa ao pós-tratamento de efluentes de reatores anaeróbios com vistas à remoção de matéria orgânica carbonácea e nitrogênio. Como material suporte, foram utilizados cubos de espuma de poliuretano com aresta de 5 mm. Foram realizados ensaios de caracterização hidrodinâmica no RAALF para obtenção do padrão de escoamento. Também foi verificada a viabilidade da utilização de biogás como doador de elétrons para a desnitrificação. Avaliou-se a influência da variação do tempo de detenção hidráulica e da diferente composição e concentração biogás do nos processos. O RAALF foi operado a uma temperatura de 30±2°C. Os resultados obtidos a partir dos estudos hidrodinâmicos indicaram que o escoamento do reator tende a pistonado. A nova configuração de reator permitiu a ocorrência dos processos de interesse, seja remoção de matéria orgânica carbonácea (com eficiências de até 98%), seja remoção de nitrogênio via nitrificação-desnitrificação (com eficiências acima de 90%). A utilização de biogás na desnitrificação mostrou-se viável e a taxa de desnitrificação foi maior na sub-condição 2.2 (média de 178±43 g-N/\'M POT.3\'.dia), etapa na qual o doador sulfeto de hidrogênio foi fornecido em alta concentração (50 g\'M POT.3\'). Foi possível detectar intermediário (metanol) a partir da oxidação parcial do metano, ainda que de forma inconstante. Resultados de atividade desnitrificante e número mais provável evidenciaram a coexistência da desnítrificação autotrófica e heterotrófica na câmara anóxica. O reator mostrou capacidade adicional como um sistema de tratamento de gases, atingindo eficiência de remoção de 100% para o \'H IND.2\'S\' e acima de 60% para o \'CH IND.4\'. De maneira geral, os resultados demonstram o potencial do RAALF como alternativa para pós-tratamento de esgoto sanitário de efluentes de reatores anaeróbios.This work presents the Aerobic-Anoxic Fix Bed Reactor (AAFBR), with superimposed chambers, as an alternative concerning the post-treatment of anaerobic reactors efiluents aiming the removal of carbonaceous organic matter and nitrogen. Polyurethane foam cubic matrices (5 mm) were used packing material. Hydrodynamic essays were carried out in order to obtain the flow pattern and to verify the influence of air bubbles on the behavior of liquid flow. The hydrogen sulfide and methane (synthetic biogas) were evaluated as electron donors to denitrification. The influence ofboth hydraulic retention time (down-flow velocity) and the concentration of gases from the synthetic mixture were evaluated. The main performance parameters were evaluated by the hand of physico-chemical analysis, besides the observation of the microorganisms involved in the processes. AAFBR was operated under a temperature of 30±2°C. The innovative reactor configuration enabled the occurrence of the processes aimed, such as carbonaceous organic matter removal (efficiencies higher than 90%), or nitrogen via nitrification-denitrification (efficiencies higher than 90%). Denitrification rates (178±43 g-N/\'M POT.3\'.dia) were higher during the condition 2.2, in which high concentrations of hydrogen sulfide (50 g\'M POT.3\') were applied into the reactor. Methanol was the only intermediate detected from the partial oxidation of methane. Results obtained from the denitrifying activity and most probable number indicated the coexistence of both autotrophic and heterotrophic denitrification in the anoxic chamber. AAFBR showed additional ability as gas removal system, achieving global removal efficiencies of 100% for \'H IND.2\'S\' and above 60% for \'CH IND.4\'. Overall, the results showed that AAFBR has potential to be used as an alternative for the tertiary treatment of wastewater

Utilization of different packing materials in the hydrogen sulfide biofiltration

O sulfeto de hidrogênio é um gás que pode causar os mais diversos danos se lançado ao meio ambiente devido, principalmente, à sua elevada toxicidade, corrosividade, odores indesejáveis e alta demanda de oxigênio. Atualmente existem diferentes processos físico-químicos estabelecidos para o tratamento desse composto, entretanto são consideradas técnicas onerosas do ponto de vista econômico e ambiental. Os processos biológicos constituem-se como uma alternativa bastante interessante quando comparados aos processos físico-químicos, sendo que a biofiltração é o processo mais amplamente utilizado. Neste trabalho, foram avaliados três tipos diferentes de materiais suporte, sendo um sintético - espuma de poliuretano - e dois orgânicos - fibra de côco e bagaço de cana -, para a biofiltração de uma mistura gasosa contendo \'H IND.2\'S\'. Como inóculo, optou-se pela utilização de cultura mista originária de duas fontes: a) unidade de biofiltro aerado submerso pertencente ao Serviço Autônomo de Água e Esgoto da Cidade de São Carlos, b) unidade de lodos ativados pertencente a São Carlos S/A - Indústria de Papel e Celulose. A adaptação do inóculo foi realizada em meio nutriente específico. Foi observado um período de partida de somente 2 dias nos três sistemas. Com o intuito de avaliar o impacto do aumento progressivo das taxas de carregamento mássico no desempenho dos três biofiltros, os mesmos foram submetidos a taxas de 19, 32, 54 e 70 g/m³.h (concentrações afluentes médias de 184, 328, 526 e 644 ppm para tempo de retenção do gás de, aproximadamente, 50 segundos). As eficiências remoção média em todos os sistemas mantiveram-se sempre acima dos 99,3%. A capacidade eliminação máxima alcançada pelos biofiltros oscilou entre 74 e 80 g/m³.h. As perdas de carga verificadas no ensaio hidrodinâmico foram baixas, variando entre 0,59.\'10 POT.-2\' a 0,68 \'10 POT.-2\' mca, para a velocidade superficial utilizada durante o estudo. O modelo matemático empregado na previsão do desempenho dos sistemas ajustou-se bem aos dados experimentais. Portanto, pode-se concluir que os materiais suportes testados são adequados para a biofiltração de sulfeto de hidrogênio.Hydrogen sulfide is a gas which has high restrictions regarding to its disposal in the environment, mainly, because of its high toxicity, malodors, high oxygen demand, etc. Currently, there are many different physical-chemical processes established in order to treat this compound, nevertheless they are considered expensive techniques by the point of economical and environmental views. Biological processes are very interesting alternatives when they are compared to the physical-chemical ones, and biofiltration is the most used process. In this work, three different materials as support media were evaluated, - a synthetic one - represented by the polyurethane foam, - two organic ones - represented by coconut fiber and sugar bagasse -, for a biofiltration of a gaseous mixture containing \'H IND.2\'S\'. Microorganisms were obtained from two sources: a) submerged aerated biofilter unit, b) activated sludge unit. Inoculum\'s adaptation was realized in specific nutrient media. It was observed a 2 days start-up period in the three systems. In order to evaluate some impact caused by the progressive increasing of mass loading rate on the biofilters performance, were applied rates of 19, 32, 54 e 70 g/m³.h (average influent concentrations of 184, 328, 526 e 644 ppm to the empty bed retention time of, approximately, 50 seconds). Average removal efficiencies in the systems were always above 99,3%. Maximum elimination capacities reached by the biofilters were in the range of 74 e 80 g/m³.h. Loss pressure verified by the hands of hydrodynamic essays varied between 0,59.\'10 POT.-2\' a 0,68.\'10 POT.-2\' mca, to a superficial velocity utilized during the work. Mathematical model used to predict the performance of the systems fitted reasonably the experimental data. Then, it can be concluded that the three packing materials are appropriated for the hydrogen sulfide biofiltration

Performance evaluation of packing materials in the removal of hydrogen sulphide in gas-phase biofilters: Polyurethane foam, sugarcane bagasse, and coconut fibre

The main objective of this work was to investigate three packing materials (polyurethane foam, sugar-cane bagasse, and coconut fibre) for biofiltration of a gaseous mixture containing hydrogen sulphide (H(2)S). Mixed cultures were obtained from two sources, aerated submerged biofilters and activated sludge, and were utilised as inoculums. Biofilters reached 100% removal efficiency after two clays of operation. The empty bed residence time was 495 for each of the biofilters. The reactors were operated simultaneously, and the inlet concentrations of H(2)S varied between 184 and 644 ppmv during the long-term continuous operation of the biofilters (100 clays). Average removal efficiencies remained above 99.3%, taking into consideration the entire period of operation. Average elimination capacities reached by the biofilters packed with polyurethane foam, coconut fibre, and sugarcane bagasse were in the range of 17.8-66.6; 18.9-68.8, and 18.7-72.9g m(-3) h(-1), respectively. Finally, we concluded that the packing materials tested in this work are appropriate for the long-term biofiltration of hydrogen sulphide. (C) 2010 Elsevier B.V. All rights reserved.CNPqFAPESPCAPE

Seminário de Dissertação (2024)

Página da disciplina de Seminário de Dissertação (MPPP, UFPE, 2022) Lista de participantes == https://docs.google.com/spreadsheets/d/1mrULe1y04yPxHUBaF50jhaM1OY8QYJ3zva4N4yvm198/edit#gid=

Evaluation of a quality improvement intervention to reduce anastomotic leak following right colectomy (EAGLE): pragmatic, batched stepped-wedge, cluster-randomized trial in 64 countries

Background Anastomotic leak affects 8 per cent of patients after right colectomy with a 10-fold increased risk of postoperative death. The EAGLE study aimed to develop and test whether an international, standardized quality improvement intervention could reduce anastomotic leaks. Methods The internationally intended protocol, iteratively co-developed by a multistage Delphi process, comprised an online educational module introducing risk stratification, an intraoperative checklist, and harmonized surgical techniques. Clusters (hospital teams) were randomized to one of three arms with varied sequences of intervention/data collection by a derived stepped-wedge batch design (at least 18 hospital teams per batch). Patients were blinded to the study allocation. Low- and middle-income country enrolment was encouraged. The primary outcome (assessed by intention to treat) was anastomotic leak rate, and subgroup analyses by module completion (at least 80 per cent of surgeons, high engagement; less than 50 per cent, low engagement) were preplanned. Results A total 355 hospital teams registered, with 332 from 64 countries (39.2 per cent low and middle income) included in the final analysis. The online modules were completed by half of the surgeons (2143 of 4411). The primary analysis included 3039 of the 3268 patients recruited (206 patients had no anastomosis and 23 were lost to follow-up), with anastomotic leaks arising before and after the intervention in 10.1 and 9.6 per cent respectively (adjusted OR 0.87, 95 per cent c.i. 0.59 to 1.30; P = 0.498). The proportion of surgeons completing the educational modules was an influence: the leak rate decreased from 12.2 per cent (61 of 500) before intervention to 5.1 per cent (24 of 473) after intervention in high-engagement centres (adjusted OR 0.36, 0.20 to 0.64; P < 0.001), but this was not observed in low-engagement hospitals (8.3 per cent (59 of 714) and 13.8 per cent (61 of 443) respectively; adjusted OR 2.09, 1.31 to 3.31). Conclusion Completion of globally available digital training by engaged teams can alter anastomotic leak rates. Registration number: NCT04270721 (http://www.clinicaltrials.gov)