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Abstract(s)
O objetivo deste trabalho realizado no âmbito da unidade curricular “Dissertação/Estágio” do Mestrado em Engenharia Química – Energia e Biorrefinaria na Estação de Tratamentos de Águas Residuais (ETAR) de Paço de Sousa da SIMDOURO, foi o desenvolvimento de uma instalação piloto de um digestor anaeróbio que permitisse estudar a influência de vários parâmetros do processo, tais como a proporção de lamas primárias e secundárias, na alimentação ao digestor, e a temperatura do processo, na produção de biogás. Para que este objetivo fosse atingido, foram montados 5 reatores em paralelo, e em duplicado, com proporções diferentes de lamas primárias (LP) e secundárias (LS): 100%, 60%, 50% e 40% de LP e 100% LS. Esta montagem foi sujeita a três diferentes temperaturas do banho termostático onde estes reatores estavam mergulhados, de forma a poder estudar o efeito da temperatura na gama mesófila (38 - 42 ºC). Durante este estudo foi medido o volume de biogás produzido, ao longo de 20 dias, e sempre que possível foi também determinada a sua composição (percentagem de metano, dióxido de carbono, oxigénio e sulfureto de hidrogénio). Foram realizadas análises laboratoriais àslamas de cada reator (sólidos totais, sólidos voláteis, alcalinidade, ácidos gordos voláteis, pH e temperatura) antes e depois de cada ensaio, o que permitiu estimar a produção de biogás esperada a partir da degradação dos sólidos voláteis. De acordo com a literatura esperava-se uma maior produção de biogás à temperatura de 38 ºC, diminuindo à medida que esta se aproxima da gama termófila, o que se confirmou em termos de conversão de sólidos voláteis. No entanto, os resultados experimentais nem sempre demonstram o previsto relativamente à produção de biogás, obtendo-se em alguns casos maiores produções nas temperaturas mais altas, sendo os resultados coerentes entre os reatores duplicados. Nestes últimos ensaios já tinham minimizadas as fugas de biogás tendo melhorado o funcionamento da instalação. De uma forma geral, a nível experimental obteve-se uma maior produção de biogás nos reatores com maior proporção de lamas primárias, o que está de acordo com o previsto pela literatura.
The objective of this work carried out in the course “Dissertation / Internship” of the Master in Chemical Engineering - Energy and Biorefinery at SIMDOURO's Paço de Sousa Wastewater Treatment Plant (WWTP) was the development of a pilot installation of a anaerobic digester to study the influence of various process parameters, such as the proportion of primary and secondary sludge, on the feed to the digester, and the process temperature on biogas production. To achieve this goal, 5 reactors were assembled in parallel and in duplicate, with different proportions of primary (PS) and secondary (SS) sludge: 100%, 60%, 50% and 40% of PS and 100% SS. This assembly was subjected to three different temperatures of the thermostatic bath where these reactors were immersed, in order to study the effect of temperature in the mesophilic range (38 - 42 ºC). During this study the volume of biogas produced over 20 days was measured and whenever possible its composition (percentage of methane, carbon dioxide, oxygen and hydrogen sulfide) was also determined. Laboratory analyzes were performed on the sludge of each reactor (total solids, volatile solids, alkalinity, volatile fatty acids, pH and temperature) before and after each test, allowing to estimate the expected biogas production from the volatile solids degradation. According to the literature, a higher biogas production was expected at a temperature of 38 ºC, decreasing as it approaches the thermophilic range, which was confirmed in terms of the conversion of volatile solids. However, the experimental results do not always demonstrate the predicted biogas production, and in some cases higher yields are obtained at higher temperatures, and the results are consistent between duplicate reactors. In these last tests biogas leakage had already been minimized and the operation of the plant has been improved. In general, at the experimental level, a higher production of biogas was obtained in reactors with higher proportion of primary sludge, which is in accordance with the literature.
The objective of this work carried out in the course “Dissertation / Internship” of the Master in Chemical Engineering - Energy and Biorefinery at SIMDOURO's Paço de Sousa Wastewater Treatment Plant (WWTP) was the development of a pilot installation of a anaerobic digester to study the influence of various process parameters, such as the proportion of primary and secondary sludge, on the feed to the digester, and the process temperature on biogas production. To achieve this goal, 5 reactors were assembled in parallel and in duplicate, with different proportions of primary (PS) and secondary (SS) sludge: 100%, 60%, 50% and 40% of PS and 100% SS. This assembly was subjected to three different temperatures of the thermostatic bath where these reactors were immersed, in order to study the effect of temperature in the mesophilic range (38 - 42 ºC). During this study the volume of biogas produced over 20 days was measured and whenever possible its composition (percentage of methane, carbon dioxide, oxygen and hydrogen sulfide) was also determined. Laboratory analyzes were performed on the sludge of each reactor (total solids, volatile solids, alkalinity, volatile fatty acids, pH and temperature) before and after each test, allowing to estimate the expected biogas production from the volatile solids degradation. According to the literature, a higher biogas production was expected at a temperature of 38 ºC, decreasing as it approaches the thermophilic range, which was confirmed in terms of the conversion of volatile solids. However, the experimental results do not always demonstrate the predicted biogas production, and in some cases higher yields are obtained at higher temperatures, and the results are consistent between duplicate reactors. In these last tests biogas leakage had already been minimized and the operation of the plant has been improved. In general, at the experimental level, a higher production of biogas was obtained in reactors with higher proportion of primary sludge, which is in accordance with the literature.
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Keywords
Biogás Lamas primárias Lamas secundárias Temperatura Biogas Primary Sludge Secondary Sludge Temperature