Along the Besòs river in Barcelona, innovative nature-based solutions (NBS) to mitigate groundwater pollution are deployed and validated at pilot scale. Clara Laguna-Marín, PhD student at IDAEA-CSIC, hosted a recent visit where Laura Scheiber (also from IDAEA-CSIC) and Andrea Reuvers from Future City Foundation, were guided around.
Upon arrival, the UPWATER team registered – the NBS pilot plant is on the grounds of a waste water treatment plant – and proceeded to the control house. Here, the water flow entering the pilot plant is monitored. This system supplies the pilot plant with secondary-treated wastewater from the nearby wastewater treatment facility, channeling between 1.6 and 6.5 litres per minute into the setup. The water flow is pulsed, with a brief pause after every few minutes, allowing for efficient distribution and treatment.
The core of the NBS pilot plant consists of four large concrete cells, each designed with different configurations of floating root mats and horizontal flow bioelectrochemical wetlands, utilizing biochar as a substrate. These configurations were developed based on research outcomes from prior laboratory studies:
- First cell: 25% floating root mats, 75% bioelectrochemical wetlands on biochar.
- Second cell: 50% floating root mats, 50% bioelectrochemical wetlands on biochar.
- Third cell: 75% floating root mats, 25% biochar.
- Fourth cell: 100% biochar.
Environmental and Agriculture Group
The objective of these varying set-ups is to determine which configuration most effectively removes contaminants of emerging concern (CECs) and other pollutants (nitrate, phosphate, ) from wastewater. To evaluate this, field campaigns take place, during which water samples are taken from the inlet and outlet of each section two times a week for a period of one or two months with additional samples collected at midpoint piezometers.
Over the coming months, the pilot plant will undergo further optimization and monitoring under winter conditions, focusing on the reduction of nutrients and pollutants. In April and May 2025, passive sampling devices will be used to further assess water quality across these configurations and complement the previouly gathered data.