Greening of urban areas with waste water

Czech Republic

Utility – industry symbiosis
The new water line (NWL) of the Prague WWTP is located on a Vltava river island in the middle of the city’s green area close to the Prague botanical garden, Prague zoo and the biggest Prague recreational area – Stromovka Park. The NWL is located inside a concrete containment to protect the plant from floods. The roof of the containment is covered with soil where grass, bushes and trees will be planted to create a kind of park that also includes grey-green solutions for urban development supplied by Storm Aqua, an SME partner in WIDER UPTAKE.

Objective
Demonstrate safe use of treated effluent for irrigation purposes in grey-green solutions for urban development with reasonable water transportation expenses.

Key stakeholders and partners
City of Prague, Prague botanical garden, Prague zoo, Prague services, Storm Aqua, Czech Technical University and The University of Chemistry and Technology Prague.

Prague case – innovative actions
The activity will demonstrate the feasibility of reusing wastewater in an urban setting after polishing treatment. This will include UV disinfection to be evaluated according to the bacterial quality parameters defined in the proposal of EU regulation for wastewater reuse from May 2018. Micro- and nanofiltration membranes for removal of residual concentrations of suspended solids will be demonstrated. If the water quality analyses indicate problems with reused water salinity, the experiments will be extended to include reverse osmosis. Advanced oxidation processes and sorption will be piloted for removal of pharmaceuticals and hormones. An initial evaluation has indicated that use of ozonation followed by active carbon sorption may be an efficient treatment process for these compounds. Polished wastewater will be used for irrigation of pilot scale grey-green solutions for urban development. Demonstrating the reliability of wastewater reuse for such systems will enable this as an essential element in sustainable urban water management and lead to impacts on the national/international legislation.

Outcomes
The key outcomes will be optimized and functional systems for reuse of treated wastewater to improve the microclimate of adjacent city districts, dramatically decrease demand for expensive tap water for urban irrigation, street washing and other use by the city during the summer (decreasing the effects of city thermal islands, which is a new phenomenon in Prague).

In three irrigated compartments with grass, plants and bushes we are studying influence to plants, soil and ground water. We can measure it online with camera observing.
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