1,720,998 research outputs found
Analisi respirometrica di reflui misti civili industriali finalizzata alla valutazione della trattabilità biologica
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Short-term water content analysis for the optimization of sludge dewatering in dedicated constructed wetlands (reed bed systems)
No full textThe performance of reed bed systems is usually presented following a long-term evaluation of case studies. However, short-term water content analyses may be useful to better understand the dynamics of the dewatering process and hence to rationally describe the system, with the ultimate aim of improving the system overall. In this study we performed daily water content analyses in the interval between subsequent sludge loadings in a real-scale reed bed system situated in Pisa (central Italy). Water content analyses were performed at different periods of the year: in winter, drainage quickly led to a maximum of about 8% dry matter while in summer the dewatering process significantly continued after the first week thanks to evapotranspiration. A comparative analysis of planted and unplanted beds confirmed that the mechanical function of plants is essential in the winter, when the unplanted bed did not present any dewatering capability. A semi-empirical equation describing the dynamics of the dewatering process is then proposed and calibrated. This equation forms the basis for the technical and economical optimization of the resting time in terms of required surface area and drying efficiency. An optimum of I I days resting time was finally evaluated in the presented case study
Short-term water content analysis for the optimization of sludge dewatering in dedicated constructed wetlands (reed bed systems)
No full textEvapotranspiration in constructed wetlands with subsurface flow: a limitation for water reuse?
No full textMeasurements of water content distribution in vertical subsurface flow constructed wetlands using a capacitance probe: benefits and limitations
No full textWater content profoundly affects the efficiency of vertical flow constructed wetlands. Detailed vertical water content profiles could help to improve our understanding of the behaviour of these systems. in this study we tested a capacitance probe to measure water content in a vertical flow constructed wetland pilot plant. Field measurements were compared with data recorded in a purpose-built laboratory apparatus. Our results show that the on-site assessment of water content profiles should help to identify the real layout of the vertical systems, and this in turn should prevent or at least highlight possible running failures. Theoretical hydraulic retention time, oxygen gas availability and the calibration of van Genuchten's equation for unsaturated flow were easily assessed thanks to the water content measurements. Furthermore, water content measurements performed in dynamic conditions enabled us to define the actual specific flow for the various phases of the filling-emptying processes and to check the influent ponding for a uniform distribution of wastewater over the bed. Water content measurements are quick, cheap and safe, providing a useful tool in many application areas. However, calibrating the probe for the media typically used in vertical flow bed is not simple. In addition seriously misleading measurements can arise when steep variations in water content occur in the system
Tecniche respirometriche per lo studio dei processi biologici nei terreni e nelle biomasse adese
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Valutazione delle prestazioni dei processi di fitodegradazione, rizodegradazione, fitoestrazione e fitostabilizzazione per la bonifica dei suoli inquinati
No full textTrattamenti terziari di fitodepurazione per la riqualificazione ambientale del fiume Yarqon in Israele
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