- Monitoring methods
- Mitigation solutions
- Prevention methods
Monitoring methods
Monitoring refers to a broad range of methodologies which can include tools to support water balance calculations, techniques to monitor variations in groundwater quantity or quality, the identification of contaminants of emerging concern (CECs), the use of innovative natural and human-made tracers and the identification of processes in the unsaturated zone that affect the groundwater status.
Ceramic Passive Samplers (CPS)
One of the monitoring methods used in the UPWATER case studies (Stengaarden and Barcelona) is the Ceramic Passive Sampler (CPS). These samplers are porous ceramic cylinders with a sorbent material in the centre attracting the sought contaminants. To allow the detection of contaminants in groundwater, the CPS’ porous size and sorbent material will be adapted for long-term deployment periods and for a wide number of priority pollutants. The CPS has already demonstrated its worth in another project, IMAQUA, although in raw surface water and drinking water.
Viral passive samplers (VPS)
Viral Passive Samplers (VPS) work somewhat in the same way as CPS work. These samplers sorb the virus over two to fifteen days. They provide an inexpensive and practical way to study the presence and prevalence of viral pathogens in groundwater samples. In the UPWATER project, they are deployed in observation wells in Athens and Barcelona. An innovation in this project is the coupling of VPS with a method for quantification and characterization by massive sequencing in the samples. VPS already proved functional for measuring SARS-CoV-2 virus concentrations in wastewater. However, for the use during the UPWATER project it does need adaptation to particular groundwater installation conditions and waterborne viral pathogens.
Diffusive gradients in thin films (DGT)
Another monitoring method is the diffusive gradients in thin films (DGT), also a passive sampler. This sampler consists of a specialized gel that can both bind to and allow the diffusion of contaminants, combined with a membrane filter. Contaminants pass through that filter and the diffusive gel. After the sampler has been deployed and retrieved, an analysis of the binding gel is conducted. This analysis calculates the time-weighted-average concentration of a specific element using a mathematical equation. Essentially, DGT serves as a tool to collect and later calculate the average concentration of contaminants over a specific period, making it a valuable method for environmental monitoring.
Diffusive gradients in thin films (DGT)
Another monitoring method is the diffusive gradients in thin films (DGT), also a passive sampler. This sampler consists of a specialized gel that can both bind to and allow the diffusion of contaminants, combined with a membrane filter. Contaminants pass through that filter and the diffusive gel. After the sampler has been deployed and retrieved, an analysis of the binding gel is conducted. This analysis calculates the time-weighted-average concentration of a specific element using a mathematical equation. Essentially, DGT serves as a tool to collect and later calculate the average concentration of contaminants over a specific period, making it a valuable method for environmental monitoring.
Pollution source apportionment modelling
In order to determine the origin and the proportion of each polluted recharge source within groundwater samples, the Stengaarden and Barcelona case study sites will use source apportionment modelling. The two methods involved in source apportionment include End-Member Mixing Analysis (EMMA) and Mixing Ratios Calculations (MIX).
EMMA, the first method, is a commonly applied method to identify and quantify dominant runoff sources. EMMA uses a method called Principal Component Analysis (PCA) to identify the minimum number of sources necessary to explain the chemical composition of each sampling point, only considering mixing processes. EMMA does not identify specific sources, but provides an arbitrary number that must be supported by a good conceptual model.
On the other hand, MIX is a method used to figure out where the different substances in groundwater come from. MIX works by analyzing the amounts of the ingredients in the water and trying to find the best combination that matches these amounts. It keeps adjusting and trying different combinations until it gets as close as possible to the real amounts. Also, MIX can tell us if there are any chemical reactions happening in the groundwater, like the water changing colour, minerals dissolving or forming, and other chemical changes. Notably, MIX has not previously been applied in scenarios involving a substantial number of potential sources, a wide array of chemical parameters, or diverse aquifer types and characteristics.
In essence, the aim is to utilize these source apportionment techniques to discern the sources and relative contributions of pollution within groundwater samples, with EMMA focusing on conceptual modelling support and MIX addressing source apportionment in complex situations involving numerous sources and diverse aquifer attributes.
Mitigation solutions
Moving Bed
Biofilm Reactors (MBBR)
Moving Bed Biofilm Reactors (MBBR) is a wastewater treatment
technology (a cleaning system) that The Institute of Environmental Science of
Aarhus University (AU) is exploring as a mitigation solution in the Stengaarden
case study. This innovative approach offers an alternative to energy-intensive
remediation methods. Stengaarden aims to assess its effectiveness through grab
sampling and investigate the possibility of gaining more insights through
single compound isotope ratio determinations. The AU is expert in using MBBR’s
and biofiltration technology. They specialize in applying MBBRs to remove
organic micro-pollutants from urban water and waste cycles, making it a
promising solution for addressing water quality challenges.
Floating root
mats and bioelectrochemical hybrid wetlands
The mitigation technology studied in the Barcelona case study is
the combination of floating root mats and bioelectrochemical hybrid wetlands,
whereas in the Athens case study only the infiltration bioelectrochemical wetland
will be deployed.
The hybrid constructed wetland consist of a floating root with a surface-water root mat, followed by a saturated reed bed (grass-like plant) containing electroconductive material. For bioelectrochemical wetlands several water saturated columns filled with modified electrochemical supporting materials (coke or biochar) and combined with zero valent iron (ZVI) are being assessed for the removal of CECs. ZVI is a reductant that has been shown to be effective for removing recalcitrant compounds from wastewater and recent studies suggest that its combination with microbial wetlands may enhance the attenuation of CECs from wastewater. Therefore, we expect that the combination of ZVI with root mat-bioelectrochemical wetlands will help to prevent groundwater pollution of the most recalcitrant compounds.
The solution will be first optimised at laboratory-scale and then validated in real field conditions in the Besòs river (Barcelona case study). The root mat-bioelectrochemical hybrid wetland will be optimised and validated for pollutant removal individually and in combination. CSIC is an expert in assessing the use of constructed wetlands for removing CECs from wastewater and surface water.
Preventive solutions
Partners of UPWATER will also try to prevent further damage to aquifers and other bodies of water. In Stengaarden and Denmark as a whole, they will try this by creating social awareness, by taxation and cities procurement of water. In Athens and Greece as a whole, they will try this by formulating management plans and setting up group campaigns with environmental citizen groups. In Barcelona and Spain as a whole, they will try this by improving on existing management and control plans, declarations of standards, and a social rate of the water tax.
Stengaarden: social awareness, taxation and cities procurement of water
Dissemination campaigns organised by local stakeholders will raise social awareness on toxic chemicals present in certain products. This way, consumers will be persuaded to “change their consumption habits” related to products that can harm their environment and ultimately their health. UPWATER also seeks to influence in the regulation for the domestic, industrial and agricultural uses of certain compounds, and the limitation of compounds and limits in discharges.
Athens: management plans and group campaigns
The Hydrogeology Group of the National Technical University of Athens (NTUA) collaborates with the main local stakeholders in the region, such as the General Secretariat for Natural Environment and Water (GSNEW), the Decentralised Administration of Attica-Water Directorate (DAA-WD), the Authority for Geology and Mineral Exploration of Greece and the Directorate of Flood Protection Works of Attica Regional Authority. Their focus is to implement relevant EU legislation at the regional level. They will also work on participatory activities in collaboration with local environmental voluntary groups, focusing on flood monitoring.
Barcelona: improving existing management and control plans, declarations of standards, social rate of the water tax
Several existing plans, programs and procedures are already in place. For example, there are the Management Plan and Program of Measures, the Discharge sanitation program, the Declaration of Water Use and Pollution and the Drought plan. The outcome of the UPWATER project might ask for adaptation and changes.