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Although Germany is not considered a water-poor country, there exist regional differences in water supply and consumption. During the past 15 years, the greywater aspect has been dealt with in Germany with a greater interest and variable success. In addition to an increased environmental awareness, water costs also play an important role in increasing the demand for advanced greywater treatment plants nstalled in buildings. Under favourable conditions, the amortisation costs usually lie between 5 and 7 years. Systems that have been extensively tried and tested and have been shown to be most reliable are those employing an advanced biological treatment followed by an UV disinfection. Systems based on membrane technology are being developed and researched intensively in Germany for municipal wastewater treatment. However, so far they play no role in greywater recycling. Greywater systems operating under low energy and maintenance requirements without the use of chemicals are mostly favoured. In Germany, greywater recycling systems should be registered at the Health Office in order to guarantee that no cross-connections exist with the drinking water network and that pipes are labelled according to regulations. The hygienic requirements for recycled greywater, which is primarily used for toilet flushing, are oriented towards the EU-Guidelines for Bathing Waters. The use of recycled greywater for irrigation purposes is minor. As to the use of recycled water for laundry, the first promising investigation results are now available.

The COVID-19 pandemic unveiled the fragility of food sovereignty in cities and confirmed the close connection urban dwellers have with food. Although the pandemic was not responsible for a systemic failure, it suggested how citizens would accept and indeed support a transition toward more localized food production systems. As this attitudinal shift is aligned with the sustainability literature, this work aims to explore the tools and actions needed for a policy framework transformation that recognizes the multiple benefits of food systems, while considering local needs and circumstances. This perspective paper reviews the trends in production and consumption, and systematizes several impacts emerged across European food systems in response to the first wave of pandemic emergency, with the final aim of identifying challenges and future strategies for research and innovation toward the creation of resilient and sustainable city/region food systems. The proposal does not support a return to traditional small-scale economies that might not cope with the growing global population. It instead stands to reconstruct and upscale such connections using a “think globally act locally” mind-set, engaging local communities, and making existing and future citizen-led food system initiatives more sustainable. The work outlines a set of recommended actions for policy-makers: support innovative and localized food production, training and use of information and communication technology for food production and distribution; promote cross-pollination among city/region food systems; empower schools as agents of change in food provision and education about food systems; and support the development of assessment methodologies and the application of policy tools to ensure that the different sustainability dimensions of the food chain are considered.

A three-stage constructed wetland for leachate treatment was monitored on a landfill at a pilot scale. The plant had been designed to achieve at least 75% nitrogen removal. NH4-N input concentration was 240 (median) up to 290 mgl(-1) and COD concentration was 455 to 511 mgl(-1), respectively. A 14 m2 vertical flow sand filter plus a 14 m2 horizontal flow sand filter followed by a 3.3 m2 vertical flow sand filter was chosen. Acetic acid was added to the horizontal flow system for denitrification. The results showed a very stable nitrification rate within the vertical flow system of 94% (median) at NH4-N loading rates of about 10 (median) up to 17 gm(-2)d(-1). Denitrification was mainly dependent on the dosing of acetic acid and could reach a maximum of 98%. One interesting effect was the production of nitrite in the horizontal flow sand filter. This could efficiently be eliminated by the subsequent vertical flow sand filter. The chosen concept proved to be very effective for nitrogen removal. In combination with a final activated carbon filter the COD effluent concentrations could be easily and safely controlled. The design of denitrification reed beds showed a further potential for optimization.