CS #3: Water reuse from a wastewater treatment plant with a high share of industrial wastewater, Barcelona Province
Partners: EURECAT, CBT, IDAEA-CSIC
Eurecat team members with the electrochemical cell used to study the degradation of PFAS (@Eurecat)
Our Aim: Obtain water for irrigation from industrial wastewater
Approximately 60-80 percent of the region's treated wastewater flows into the Besós River. This includes not only urban effluents, but also secondary effluents from industrial wastewater (chemical, pharmaceutical, food, leather, and textile sectors) treated at the Montornès del Vallès treatment plant. As a result, these discharges introduce contaminants such as PFAS and iPMTs into the river.
The Consorci Besòs Tordera (CBT), along with partners such as Eurecat and the Catalan Water Agency, which is responsible for water planning and management in Catalonia, are collaborating to promote water reuse in the Besòs River basin. This initiative is particularly crucial in the arid regions of Catalonia, where water restrictions and consumption cuts are frequently implemented due to severe droughts. Consequently, the availability of freshwater for agricultural irrigation is limited. To address this shortage, treated wastewater could serve as an alternative source for agricultural irrigation.
The technological strategy for water reuse involves a hybrid treatment combining e-Peroxone (ozonation and electrochemical oxidation) followed by a nature-based post-treatment. This approach aims to cost-effectively remove microcontaminants and transformation products, making the water suitable for agricultural irrigation. The transfer of contaminants from reclaimed water to crops will be evaluated, and the risk to human health from direct consumption (crops) and indirect consumption (fodder for cattle) will be quantified. Our goal is not only to provide technical solutions, but also to advise farmers on crop selection and agricultural best practices to minimize the transfer of contaminants into the edible parts of crops.
Wastewater treatment plant in Montornès del Vallès (@CBT)
The Urban River Lab in Montornès del Vallès (@CBT)
What we have done so far...
Several distinct contaminants were identified in the water discharged from the wastewater treatment plant, encompassing pharmaceuticals, industrial chemicals, pesticides, drugs, and various other categories of substances. Following this identification, a prioritization process was undertaken to select target pollutants, specifically focusing on ≥20 iPMTs and ≥5 PFAS. This prioritization considered factors such as their toxicity, mobility, persistence, and concentration levels.
A comprehensive experimental e-Peroxone system was developed, including an electrochemical cell, ozone (O3) generator, ozone reactor, and piping infrastructure. Initial laboratory-scale were conducted to explore the degradation pathways and transformation products of PFHxA, PFBS, and PFHxS. Additionally, optimal oxidative conditions for the removal of PFAS and iPMTs were determined based on degradation rates and energy consumption.
These bench-scale experiments enabled us to investigate the production of oxidation by-products from chloride and bromide during e-Peroxone treatment. Subsequently, some experiments were conducted at pilot scale using the Electrochemical Advanced Oxidation Processes (EAOPs) prototype to establish operational conditions at the Montornès del Vallès treatment plant. Pilot-scale operations at this site commenced on April 9, 2024, and are scheduled to conclude on July 26, 2024, covering a total of 16 weeks of operation.
The PROMISCES consortium leveraged its prior experience to design and construct two small wetlands. Each constructed wetland channel measures 74 cm in width, 47 cm in depth, and 3 m in length, featuring two plant species: Iris pseudacorus and Phragmites sp. In March 2024, the EAOP prototype was connected to these constructed wetlands. To ensure optimal operation, a filtration system to reduce total dissolved solids concentration in the WWTP effluent was also constructed.
Furthermore, various studies have been initiated to investigate the impact of reclaimed water on crop irrigation. One study examines the uptake of PFAS and iPMTs by lettuce irrigated with reclaimed water from the EAOP/constructed wetlands. Additional studies aim to assess the presence of pollutants in lettuces irrigated with (i) water spiked with known concentrations of specific pollutants and (ii) surface water that receives treated wastewater from a water reclamation plant. Finally, in this case study, a separate toxicity assessment will be conducted by collecting selected samples from each stage of the treatment process.
