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Publication
Sistemas de desodorização e ventilação em estações de tratamento de águas residuais
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Abstract(s)
Nas estações de tratamento de águas residuais (ETAR) a emissão de odores desagradáveis é um risco constante, e a proximidade com áreas povoadas torna-os um problema, visto que reduz a qualidade do ar e, consequentemente, a qualidade de vida da população. Como solução os espaços de tratamento são cobertos para conter os odores. No entanto, a cobertura por si só não é o suficiente, necessitando de um sistema de ventilação e desodorização para assegurar as concentrações de poluentes aceitáveis, tanto nos espaços confinados com ou sem presença humana, quanto no ar libertado para o exterior. O presente trabalho teve como objetivo analisar e otimizar dois sistemas de ventilação e desodorização da ETAR de Frielas: a "linha da torre 1", que extrai ar da 1ª elevação inicial, gradagem e oficinas, e a "linha da torre 2", que extrai ar do canal de medição, edifício de desarenamento/desengorduramento, decantação primária e elevação secundária. Através das visitas técnicas foram identificadas deficiências e comparados os caudais e pressões medidos com os valores do projeto. Posteriormente, foi elaborada uma lista de melhorias e redimensionada a linha da torre 1, pois a linha da torre 2 estava inoperacional. Para a torre 1, foram propostas duas configurações, dimensionadas para três cenários, envolvendo o encerramento da linha das oficinas, o aumento das renovações horárias na gradagem (8/10/20 ren/h) e a extração de ar do 2º estágio de elevação (3/5/6 ren/h). Embora, a solução 1 seja mais simples de implementar por ser a extensão da configuração atual, a solução 2 apresenta uma ventilação mais eficiente, menores perdas de carga e custos energéticos (Cenário 1: -3,5%; Cenário 2: -6,1%; Cenário 3: -18,8%). No fim, foram propostos dois ventiladores com uma redução mínima de custos energéticos de 51%.
Abstract The emission of unpleasant odors represents a constant risk in wastewater treatment plants (WWTPs). Proximity to populated areas serves to exacerbate this problem, as it reduces air quality and consequently impacts the quality of life of the population. As a solution, treatment spaces are covered to contain odors; however, this approach is insufficient in isolation. It is essential to implement a ventilation and deodorization system to ensure that pollutant concentrations within confined spaces, regardless of human presence, and in the released air are within acceptable limits. The objective of this work was to analyze and optimize two ventilation and deodorization systems at Frielas WWTP: the "Tower 1 line," which extracts air from the 1st elevation, screening, and workshops, and the "Tower 2 line," which extracts air from the measurement channel, sand/grit removal building, primary sedimentation, and secondary elevation. During the technical visits, deficiencies were identified, and the measured flow rates and pressures were compared with the project values. Subsequently, a list of improvements was compiled, and the Tower 1 line was resized, as the Tower 2 line was inoperable. Two configurations were proposed for Tower 1, designed for three scenarios involving the shutdown of the workshop line, the increase in air changes in the screening area (8/10/20 air changes/h), and extraction in the 2nd elevation stage (3/5/6 air changes/h). Although Solution 1 is simpler to implement as it is an extension of the current configuration, Solution 2 offers more efficient ventilation, reduced pressure losses, and lower energy costs (Scenario 1: -3.5%; Scenario 2: -6.1%; Scenario 3: -18.8%). Finally, two fans were proposed with a minimum energy cost reduction of 51%.
Abstract The emission of unpleasant odors represents a constant risk in wastewater treatment plants (WWTPs). Proximity to populated areas serves to exacerbate this problem, as it reduces air quality and consequently impacts the quality of life of the population. As a solution, treatment spaces are covered to contain odors; however, this approach is insufficient in isolation. It is essential to implement a ventilation and deodorization system to ensure that pollutant concentrations within confined spaces, regardless of human presence, and in the released air are within acceptable limits. The objective of this work was to analyze and optimize two ventilation and deodorization systems at Frielas WWTP: the "Tower 1 line," which extracts air from the 1st elevation, screening, and workshops, and the "Tower 2 line," which extracts air from the measurement channel, sand/grit removal building, primary sedimentation, and secondary elevation. During the technical visits, deficiencies were identified, and the measured flow rates and pressures were compared with the project values. Subsequently, a list of improvements was compiled, and the Tower 1 line was resized, as the Tower 2 line was inoperable. Two configurations were proposed for Tower 1, designed for three scenarios involving the shutdown of the workshop line, the increase in air changes in the screening area (8/10/20 air changes/h), and extraction in the 2nd elevation stage (3/5/6 air changes/h). Although Solution 1 is simpler to implement as it is an extension of the current configuration, Solution 2 offers more efficient ventilation, reduced pressure losses, and lower energy costs (Scenario 1: -3.5%; Scenario 2: -6.1%; Scenario 3: -18.8%). Finally, two fans were proposed with a minimum energy cost reduction of 51%.
Description
Dissertação para obtenção do grau de Mestre em Engenharia Mecânica, na Área de Especialização de Energia, Refrigeração e Climatização
Keywords
Odor Ventilação Qualidade do ar Estação de tratamento de águas residuais Odour Ventilation Air quality Wastewater treatment plant
Citation
OLIVEIRA, Beatriz Guadalupe Costa de – Sistemas de desodorização e ventilação em estações de tratamento de águas residuais. Lisboa: Instituto Superior de Engenharia de Lisboa. 2024. Dissertação de Mestrado.