Search Results (3)

To solve the upcoming environmental problems, sponge city concepts as well as new technologies are being developed these days. One of the future challenges is to reduce drinking water demand by using decentralized water recycling systems. This study aimed to investigate the performance of a specially designed pilot wetland roof (PWR) treating domestic greywater (GW) at ground level under outdoor conditions and to evaluate the effects of different hydraulic loading rates (HLRs) for a period of two years. The results showed highly efficient removal of typical greywater pollutants from the system, e.g., five-day biochemical oxygen demand (BOD₅) > 96%, chemical oxygen demand (COD) > 93%, total suspended solids (TSS) >94%, anionic surfactants (AS) > 94%, ammonium-nitrogen (NH₄-N) > 84%, total nitrogen (TN) > 71%, total phosphorous (TP) > 87%, and E. coli (1.86 ± 1.54 log-removal). The mean concentrations of the targeted parameters at the outflow were in compliance with the requirements for discharge to the environment and met reclaimed water quality standards for agricultural irrigation, except for E. coli. Statistically significant (p < 0.05) results of pollutant mass removal rate across different HLRs indicated the potential effect of HLR on treatment performance, and HLR in a range of 67–80 L m^–2 d^–1 contributed to a higher removal efficiency without compromising the limit values. A comparatively low HLR of 45 L m^–2 d^–1 should be applicable if pathogen removal is the most important requirement. Plant species showed good plant vitality and adapted well to the water storage mat. The higher the mean ambient air temperature, the greater runoff reduction (>50%) was observed due to high evapotranspiration. The results showed the system is a promising green technology for GW recycling and can be scaled up for application to urban buildings. Full article

The effects of climate change in coastal semi-arid and arid Mediterranean areas are intense. Green roofs planted with native plant species that are able to withstand saline conditions can contribute to supporting climate-change adaptation and species preservation in wetlands, enhancing the character of local landscapes and reducing disaster risk. Considering the limited availability of water resources, there is increasing interest in the use of seawater for irrigation, particularly near coastal areas. The growth of a native Mediterranean halophyte, Arthrocnemum macrostachyum, on a simulated extensive green roof system with six different irrigation treatments with or without seawater for 97 days is presented. The irrigation treatments included tap water every 4 or 8 days, seawater every 4 or 8 days, and seawater alternated with tap water every 4 or 8 days. The plants’ growth indices, heights, ground-cover surface areas, and relative shoot water content, as well as the electrical conductivity of the green roof’s substrate leachates (EC_L), were measured at regular intervals. Overall, the plants irrigated with tap water every 4 days and the plants irrigated with seawater alternated with tap water every 4 days showed the greatest growth amongst the different irrigation treatments, while the plants irrigated with seawater or seawater alternated with tap water every 8 days showed the least growth. Furthermore, the plants irrigated with tap water every 8 days or seawater every 4 days showed intermediate growth. To conserve water, irrigation with seawater alternated with tap water every 4 days is proposed. To further conserve water, irrigation every 4 days with seawater only is also proposed. Full article

While constructed wetlands have become established for the decentralized treatment of wastewater and rainwater, wetland roofs have only been built in isolated cases up to now. The historical development of wetland roofs is described here on the basis of a survey of literature and patents, and the increasing interest in this ecotechnology around the world is presented. In particular, this article describes the potential for using wetland roofs and examines experience with applications in decentralized water management in urban environments and for climate regulation in buildings. Wetland roofs are suitable as a green-blue technology for the future—particularly in cities with an acute shortage of unoccupied ground-level sites—for the decentralized treatment of wastewater streams of various origins. Positive “side effects” such as nearly complete stormwater retention and the improvement of climates in buildings and their surroundings, coupled with an increase in biodiversity, make wetland roofs an ideal multi-functional technology for urban areas. Full article