Utilize este identificador para referenciar este registo: http://hdl.handle.net/10400.6/3430
Título: Development of a capacitive probe for water level measurement in filtration beds
Autor: Dias, Daniel Filipe Cristelo
Orientador: Albuquerque, António João Carvalho de
Espírito Santo, António Eduardo Vitória do
Palavras-chave: Tratamento de águas residuais
Tratamento de águas residuais - Filtração
Tratamento de águas residuais - Meio filtrante
Tratamento de águas residuais - Medição de nível
Leito de macrófitas
Wastewater treatment
Capacitive probe
Filtration beds
Data de Defesa: 2012
Resumo: Wastewater treatment processes by filtration (e.g. trickling filters, filter beds or constructed wetlands) are widely used for treating several types of wastewater, being a suitable solution for small urban agglomerates. Typically, the flow measurement is installed at the entrance of the plant (in the preliminary treatment) or at the entry of the filtration system, and there is no registration of flow rate in other points, which could be especially useful for the control of hydraulic loads and bed clogging and for evapotranspiration estimates. The existing water level meters are heavy to transport or difficult to setup in various points of filter beds and in addition may be an expensive technology for replication throughout the bed area. This work aimed to develop a light water level sensor, easy to transport and install, robust and with reliable readings, which could be installed at various points of a filtration treatment system. The developed sensor includes a capacitive probe, a data-logger and a computer interface. The system has a capacitive probe that changes depending on the water level. The capacitive value is measured with an appropriated method. The data-logger allows saving multiple records of capacity in time, while the interface can send data to a computer. Laboratory tests were conducted to determine the calibration curves that allow data to be converted from capacity to water height (or water level). These curves have been validated with laboratory measurements. The horizontal subsurface flow constructed wetland of Vila Fernando (Guarda) was used for experimental measurements of water level in 35 measuring points. Since at real scale there are adverse conditions that can interfere with either the probe or with the data-logger readings, laboratory experimental assays were conducted to evaluate the effects of salinity, temperature and wastewater characteristics on the quality of measurement. it was concluded that the water level meter (probe and data-logger) responded satisfactorily to these variations. However, additional tests are needed to evaluate the effect of these and other parameters such as humidity, in long-term measurements. The battery lifetime for feeding the data-logger is another aspect that has to be improved. The results of two months measurements show that the probe measurements were correct, fallowing the pattern of the flow pumped from upstream and has also been possible to verify that the bed is already clogged in three regions near the entrance. Therefore, in addition to water level measurements, this technology allowed an indirect detection of a problem (bed clogging), which would not be possible to identify with the conventional water level measurement.
URI: http://hdl.handle.net/10400.6/3430
Designação: Dissertação apresentada à Universidade da Beira Interior para a obtenção do grau de mestre em Engenharia Civil
Aparece nas colecções:FE - DECA | Dissertações de Mestrado e Teses de Doutoramento

Ficheiros deste registo:
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Capa Daniel Dias.pdf200,65 kBAdobe PDFVer/Abrir
Daniel Dias - Tese 2012.pdf5,18 MBAdobe PDFVer/Abrir

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