Influence of oxygen concentrations and different aeration flow rates in carbon content of old waste: Lab-scale bioreactor landfills

• Autor(a) principal: Cerqueira, Catarina Sofia Madureira
• Data de Publicação: 2017
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/50894
• topic: MSW; Bioreactor; In situ aeration; Oxygen concentration in the outlet gas; Carbon removal; Carbon balance; Domínio/Área Científica::Engenharia e Tecnologia::Engenharia do Ambiente

Operating a bioreactor with in situ aeration has been consider as a proper method to accelerate the degradation of organic matter and consequently, to have a rapid stabilization and settlement of MSW. Lab-scale tests were carried on a 30-year-old waste, from Legnago landfill, to study the improvement of new alternatives for the current re-disposal of the waste. This research aimed to accomplish a better stabilization of the waste and, subsequently, a reduction of the emissions, focusing on carbon content removal. Carbon mass balance was performed to assess the carbon removal pathways. Additionally, oxygen concentrations in the outlet gas were evaluated to understand if can be considered as a beneficial tool for the landfill dimensioning and operation, in order to adjust the aeration rate. In six bioreactors, different aeration rates were adjusted over time to provide stable oxygen concentrations in the outlet gas on five bioreactors, and one column was set-up under anaerobic conditions to simulate the real conditions of the waste in the landfill. Concentrations of carbon compounds and ammonia nitrogen were higher in the leachate of the anaerobic bioreactor than the aerated ones, which acknowledges a better development with air injection on the waste. During the experiment, the lowest aerated column with an inlet of 5.6 L O2/kg of waste and a mean value of 0.4% O2 in the outlet gas reported the best performance of aeration efficiency in terms of carbon removal, regarding the oxygen supplied. Concerning the carbon balance, it was recognized that most of carbon content was removed via gas than via leachate. More than 90% of carbon removed was converted into carbon dioxide due to aerobic degradation processes. At the end of the study, defining oxygen concentrations in the outlet gas turned out to be an appropriate and a beneficial tool to design and operate an aerobic bioreactor.