Algeciras

Location: The NICE Urban Real Lab is located within the Port of Algeciras (Andalucia, Spain), one of the largest in the EU.

Context: This location was proposed within the context of the 'Lago Maritimo' project, a broader plan that includes several actions to regenerate the environment of the bay and reclaim this urban area for use by citizens of Algeciras. Algeciras is the biggest urban area in Campo de Gibraltar (Cádiz, Andalusia), Spain, with ~260,000 inhabitants.

Climate:Algeciras has a Mediterranean climate with decrasing rain fall events due to the climate change phenomenon. High intensity storms can occur during summer in autumn, causing abundant runoff from the city into the port area. Run-off carries sediments and antropogenic pollutants that are discharged into the bay.

Typology:Innovative multi-stage wetland, combining horizontal and vertical flow to treat Storm Water and Grey Water.

Description:

The pilot at Algeciras will test the capacity of nature-based solutions to treat run-off pollutants at the source, preventing them to be discharged into the bay. Additionally, this pilot is simultaneously treating Storm Water and Grey Water. This typology has a Storm Water and a Grey Water storage tank, followed by a hybrid multi-stage wetland. This hybrid system is composed by 70m² area treating stormwater with a maximum flow of 35 m³/h and a 15m² area treating grey water with a maximum flow of 10m³/h. Each of the systems is fed with a tank of 20 m³ each.

Main technological innovation:

• This pilot is combining treatinng grey water and storm water at the same time.
• It is integrating hybrid treatment wetland systems using a saturated bottom for water storage (Using a saturated bottom for water storage is a key innovation in particular for this climatic context, as it enables compensation of water loss by evapotranspiration due to the high temperatures, thus avoiding the plants irrigation in the dryest periods)

Synergies:

•  INRAE Research institution technological results to inspire the design with saturated layer at the bottom of the constructed wetlands.
•  INRAE Research institution to support in technological innovation for the design of hybrid treatment wetland.

To avoid clogging issues, this pilot uses adsorbent material tested by NICE experts at CETIM, a research institution. In this climatic context, it can happen that infrequent storm events cause an accumulation of sediments over nearby surfaces. During high intensity rainfall events, these sediments are then carried by run-off. This poses a serious risk of clogging in systems designed to retain and treat water from run-off, such as this pilot. One of the technological innovations developed by CETIM, (use of adsorbent material) has been introduced into the design of this pilot. The rationale is that it will allow reduction of clogging issues in the future, particularly with high concentration of solids from isolated, high-intensity rainfall events.

This pilot is of particular importance as this type of technology has traditionally been developed in more humid northern European countries. In this way, the knowledge acquired during the project will be useful for the transferability of NbS for water treatment in impaired watersheds  with similar characteristics to the climate of the region of Algeciras, (European coastal cities located in an arid or semi-arid areas).