Permeable pavements are a type of sustainable urban drainage system (SUDS)technique that are used around the world to infiltrate and treat urban Stormwater runoff and to minimize runoff volumes. Urban stormwater runoff contains significant concentrations of suspended sediments that can cause clogging and reduce the infiltration capacity and effectiveness of permeable pavements. It is important for stormwater managers to be able to determine when the level of clogging has reached an unacceptable level, so that they can schedule maintenance or replacement activities as required. Newly-installed permeable pavements in the Netherlands must demonstrate a minimum infiltration capacity of 194 mm/h (540 l/s/ha). Other commonly used permeable pavement guidelines in the Netherlands recommend that maintenance is undertaken on permeable pavements when the infiltration falls below 0.50 m/d (20.8 mm/h). This study used a newly-developed, full-scale infiltrationtest procedure to evaluate the infiltration performance of eight permeable pavements in five municipalities that had been in service for over seven years in the Netherlands. The determined infiltration capacities vary between 29 and 342 mm/h. Two of the eight pavements show an infiltration capacity higher than 194 mm/h, and all infiltration capacities are higher than 20.8 mm/h. According to the guidelines, this suggests that none of the pavements tested in this study would require immediate maintenance.
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Permeable pavements are a type of SUDS that are becoming more common to allow infiltration, to minimize runoff volumes and to treat urban water stormwater by soil filtration. However, urban stormwater runoff contains significant concentrations of suspended sediments that can cause clogging and reduce the infiltration capacity and effectiveness of permeable pavements. This study used a full-scale infiltration test procedure to evaluate the infiltration performance of 20 permeable pavements that have been in service for over 2 to 9 years in the Netherlands. The observed infiltration capacities range between 20 and 342 mm/h.
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Saturated hydraulic conductivity (Ks) of the filler layer in grassed swales are varying in the changing environment. In most of the hydrological models, Ks is assumed as constant or decrease with a clogging factor. However, the Ks measured on site cannot be the input of the hydrological model directly. Therefore, in this study, an Ensemble Kalman Filter (EnKF) based approach was carried out to estimate the Ks of the whole systems in two monitored grassed swales at Enschede and Utrecht, the Netherlands. The relationship between Ks and possible influencing factors (antecedent dry period, temperature, rainfall, rainfall duration, total rainfall and seasonal factors) were studied and a Multivariate nonlinear function was established to optimize the hydrological model. The results revealed that the EnKF method was satisfying in the Ks estimation, which showed a notable decrease after long-term operation, but revealed a recovery in summer and winter. After the addition of Multivariate nonlinear function of the Ks into hydrological model, 63.8% of the predicted results were optimized among the validation events, and compared with constant Ks. A sensitivity analysis revealed that the effect of each influencing factors on the Ks varies depending on the type of grassed swale. However, these findings require further investigation and data support.
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The EU Climate and Energy Policy Framework targets a 40% reduction in Greenhouse Gases (GHGs) emission by companies (when compared to 1990’s values) in 2030 [1]. Preparing for that future, many companies are working to reach climate neutrality in 2030. For water and wastewater treatment plants aeration processes could represent up to 70% of the whole energy consumption of the plant. Thus, a process which must be carefully evaluated if climate neutrality is a target. VortOx is an alternative to reduce power consumption in aeration processes. It is structured to test the applicability of geometrically constrained vortices in a hyperbolic funnel (aka “Schauberger”- funnel) as an innovative aeration technique for this industry. Recent investigations have shown that such systems allow an average of 12x more oxygen transfer coefficients (KLa) than that of comparable methods like air jets or impellers [10]. However, the system has a relatively small hydraulic retention time (HRT), which compromises its standard oxygen transfer ratio (SOTR). Additionally, so far, the system has only been tested in pilot (lab) scale. Vortox will tackle both challenges. Firstly, it will test geometry and flow adaptations to increase HRT keeping the same KLa levels. And secondly, all will be done using a real scale hyperbolic funnel and real effluent from Leeuwarden’s wastewater treatment plant demo-site. If proven feasible, Vortox can be a large step towards climate neutral water and wastewater treatment systems.
