Search Results (5)

Water scarcity affects at least 11% of the population and 17% of the territory of the European Union. Simultaneously in cities there is a problem of urban floods caused by violent and intense rainfalls. Decentralized drainage systems are designed to capture rainwater runoff at the place of precipitation and improve the hydrological conditions through the use of surface and subsurface infiltration, retention, and evapotranspiration techniques. The purpose of this paper was to evaluate the financial profitability of selected Low Impact Development (LID) methods for decentralized management of rainwater disposed from the roofs of two different buildings. In the presented conditions, the use of dual installations and infiltration tunnels turned out to be cost-effective solutions, whereas infiltration boxes were unprofitable for both buildings. The most unprofitable solution would become profitable if the investment costs were reduced by as much as 67% or if it was possible to generate 2.28 times more benefits. Although the research was carried out for specific conditions, the obtained results may be helpful in the implementation of similar investments. They are also a kind of contribution to the assessment of the cost-effectiveness of LID on a global scale due to the universality of the proposed research methodology. Full article

Urban water infrastructure (UWI) comprises the main systems, including water supply systems (WSS), urban drainage/stormwater systems (UDS) and wastewater systems (WWS). The UWI needs to be resilient to a wide range of shocks and stresses, including structural failures such as pipe breakage and pump breakdown and functional failures such as unmet water demand/quality, flooding and combined sewer overflows. However, there is no general consensus about the resilience assessment of these systems widely presented by various research works. This study aims to critically review the approaches, strategies and applications of the resilience assessment for the complex systems in UWI. This review includes examining bibliometric analysis, developed frameworks related to resilience assessment to help comprehend resilience concepts for the specified UWI systems in urban settings, strategies for improving resilience, resilience indicators and common tools used for modelling resilience assessment in UWI. The results indicate that resilience assessment has primarily been conducted in developed countries, underscoring the macroeconomic significance of UWI. Three key areas have been identified for analysing resilience in UWI: system design, development of resilience concepts and implementation of green infrastructure. Moreover, it has been discovered that although resilience is commonly defined using technical approaches, a more comprehensive understanding of resilience can be gained through a holistic approach. Furthermore, while strategies such as system upgrades, decentralisation, digitalisation and nature-based solutions can enhance UWI resilience, they may be insufficient to fulfil all resilience indicators. To address the challenge of effectively comparing different resilience options, it is crucial to extensively examine comprehensive and sustainability-based indicators in future research. Full article

A part of the sustainable drainage systems (SuDS) are used to treat stormwater and must be tested for their hydraulic performance and the removal efficiency to assess serviceability and retention of the pollutants efficacy for in situ use. Current test procedures provide a good basis for laboratory testing SuDS on the test stand. However, the evaluation is not sufficiently representative to compare different SuDS with each other or for in situ use. The individual steps and specifications of an applied test procedure in Germany were considered and evaluation and optimizations for the test substance and sampling methodology of SuDS on the test stand were proposed. A comparison of the particle size distribution of the test substance Millisil W4 currently in use and total suspended solids of real road runoff was made, which showed that the presented test substance of real road-deposited sediments (RDS) provides a better reference for the test conditions and they could be the basis for more representative test methods. A particle size distribution was proposed for this new test substance. Furthermore, two methods of sampling were compared, which showed that a full flow sampling is preferable to a discrete sample. At the same time, it was shown that a separation limit of 20 µm is sufficient for the determination of TSS₆₃. Full article

The vertical flow constructed wetland (VFCW) has become an attractive decentralised technology for septage treatment. One of the main purposes of the septage treatment is to reduce the volume of raw septage through dewatering, where the solids content is retained in the wetland bed and the water content is released. The retention of solids forms a layer of sludge deposit at the wetland surface, and the drained water, the so-called leachate, typically contains a lower solids content. This article reports the performance of dewatering and filtration of a pilot-scale VFCW designed for septage treatment. A comparison between two feeding strategies, hydraulic loading rate (HLR) and solids loading rate (SLR), is presented. The dewatering efficiency through drainage was found to be dependent on the solids load. The removal of total solids (TS) and chemical oxygen demand (COD) were excellent as the quality of leachate showed that more than 90% of TS and COD were retained in the system. This study reveals that the feeding based on SLR delivered a more sustainable performance for dewatering and solids removal. The build-up of sludge deposit significantly deteriorated the dewatering efficiency through drainage, but it tended to improve the filtration capacity. Full article

The use of decentralised, sustainable urban drainage systems (SUDS) for the treatment of stormwater runoff is becoming increasingly prevalent in Germany. Decentralised SUDS can offer a viable and attractive alternative to end of pipe treatment systems for stormwater runoff from urban areas. However, there is still some uncertainty regarding the long-term performance of SUDS, and the general legislative requirements for SUDS approval and testing. Whilst the allowable pollution levels in stormwater runoff that infiltrate into ground and/or water table are regulated across Germany by the Federal Soil Protection Law, there is presently no federal law addressing the discharge requirements for surface water runoff. The lack of clear guidance can make it difficult for planners and designers to implement these innovative and sustainable stormwater treatment systems. This study clarifies the current understanding of urban stormwater treatment requirements and new technical approval guidelines for decentralised SUDS devices in Germany. The study findings should assist researchers, designers and asset managers to better anticipate and understand the performance, effective life-spans, and the planning and maintenance requirements for decentralised SUDS systems. This should help promote even greater use of these systems in the future. Full article