Ligações clandestinas nos sistemas públicos de águas residuais domésticas: caso de estudo em Vila Real
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2015-10-26
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As entradas indevidas de água pluvial resultantes de ligações clandestinas nos sistemas separativos de águas residuais domésticas são uma realidade muito frequente. O aumento de caudal nos colectores nos períodos de chuva tem grandes consequências para os sistemas de drenagem de águas residuais domésticas. São dois exemplos a entrada em sobrecarga da rede com possível extravasamento de água através das tampas de saneamento ou a incapacidade de tratamento das Estações de Tratamento de Águas Residuais sobre um caudal para o qual não foram projectadas, sendo assim obrigadas a descargas nos meios receptores do excesso desse caudal. Há, por isso, um forte interesse de variadas entidades em adoptar medidas concretas que vão ao encontro das ligações clandestinas e que possam reduzir o impacto negativo que estas têm em todo o processo, ao nível estrutural, financeiro, social e ambiental.
A empresa Municipal de Águas e Resíduos de Vila Real, entidade que faz a gestão das águas residuais em Vila Real, particularmente interessada neste assunto, motivou a elaboração desta dissertação que para além de fazer uma pesquisa exaustiva, global, de metodologias e técnicas que permitem detectar e eliminar as ligações clandestinas, realiza o estudo de um sistema de drenagem de águas residuais domésticas num loteamento em Vila Real, pondo em práctica uma das técnicas de abordagem às ligações clandestinas estudadas. Este estudo consistiu no registo de leituras diárias de caudal de escoamento em tempo real e no registo de leituras diárias de ocorrência de precipitação. Com base nesses registos diários compararam-se os hidrogramas que permitiram observar o seguinte facto: quando chove, o caudal nos colectores aumenta, ou seja, um volume significativo de água é introduzido nestes mesmos colectores. Registaram-se aumentos de caudal, em alguns dias chuvosos, na ordem dos 150%.
Para trabalho futuro é também proposto um sistema a ser colocado à entrada de cada edificação, na caixa de inspecção ou mesmo no ramal de ligação ao colector público, baseado numa rede de sensores sem fios de baixo custo, com acesso remoto e autonomia energética para vários anos, a fim de controlar possíveis irregularidades nas descargas de caudais na rede separativa de águas residuais domésticas.
Improper entries of storm water due to illegal connections in wastewater drainage systems are a very common reality. The increase in public wastewater collectors flow rate, directly associated to the occurrence of rainy days, have major consequences for the wastewater drainage systems. Sewer overflow provoking leakage of water trough manholes or the incapacity of wastewater treatment plants to treat a volume of water for wich they weren’t designed and thus obliged to discharge the excess of flow in to the waterlines, are two examples of this consequences. There is therefore a strong interest from various entities that want to adopt concrete measures against illegal wastewater connections reducing the negative impact that they have throughout the process, not only at a structural level but also financial, social and environmental. The company Empresa Municipal de Águas e Resíduos de Vila Real, entity that manages wastewater in Vila Real, particularly interested in this subject, motivated this thesis that besides making an extensive global research of methods and techniques that allow detect and eliminate illegal connections, makes a study of a domestic wastewater drainage system in a subdivision in Vila Real, putting into practice one of the illicit connections techniques approaches studied. This study consisted in the register of daily flow rate readings and in the register of daily precipitation occurrence. Based on these daily records, hydrographs were compared allowing to observe the following fact: when it rained, the flow in the drainage system increased, meaning that a significant amount of water was introduced in these same collectors. In a few rainy days, increases of 150% in the flow rate were registered. For a future work is also proposed a system to be placed at the entrance of each building, on the inspection box or household connections to the public wastewater collector, based on a wireless sensor network of low cost with remote access control and energetic autonomy for several years, in order to control possible irregularities in the discharge flows to the domestic wastewater network.
Improper entries of storm water due to illegal connections in wastewater drainage systems are a very common reality. The increase in public wastewater collectors flow rate, directly associated to the occurrence of rainy days, have major consequences for the wastewater drainage systems. Sewer overflow provoking leakage of water trough manholes or the incapacity of wastewater treatment plants to treat a volume of water for wich they weren’t designed and thus obliged to discharge the excess of flow in to the waterlines, are two examples of this consequences. There is therefore a strong interest from various entities that want to adopt concrete measures against illegal wastewater connections reducing the negative impact that they have throughout the process, not only at a structural level but also financial, social and environmental. The company Empresa Municipal de Águas e Resíduos de Vila Real, entity that manages wastewater in Vila Real, particularly interested in this subject, motivated this thesis that besides making an extensive global research of methods and techniques that allow detect and eliminate illegal connections, makes a study of a domestic wastewater drainage system in a subdivision in Vila Real, putting into practice one of the illicit connections techniques approaches studied. This study consisted in the register of daily flow rate readings and in the register of daily precipitation occurrence. Based on these daily records, hydrographs were compared allowing to observe the following fact: when it rained, the flow in the drainage system increased, meaning that a significant amount of water was introduced in these same collectors. In a few rainy days, increases of 150% in the flow rate were registered. For a future work is also proposed a system to be placed at the entrance of each building, on the inspection box or household connections to the public wastewater collector, based on a wireless sensor network of low cost with remote access control and energetic autonomy for several years, in order to control possible irregularities in the discharge flows to the domestic wastewater network.
Descrição
Dissertação de Mestrado em Engenharia Civil
Palavras-chave
Sistemas de drenagem , Águas residuais , Águas pluviais , Ligações clandestinas , Sobrecarga de efluentes , Descargas ilegais