Urbanization and soil impermeabilization disrupt the natural water cycle, producing stormwater runoff that carries contaminants such as hydrocarbons, trace metal elements (TMEs), and pesticides (Makepeace et al., 1995). These pollutants, originating from urban surfaces, can harm aquatic ecosystems and groundwater. While stormwater management systems have been developed to control runoff hydraulics, their effectiveness in protecting water quality remains underexplored. The role of colloidal fractions and nanoparticles in the dynamics of contaminants in water infiltration structures must be examined in order to better control the risks of groundwater contamination. This study aims to address this by investigating TMEs in two sites.

The critical zone concept, originally applied to natural environments, must be adapted for urban areas where human activities and infrastructure shape biogeochemical processes. This research examines TME behavior in the industrial and residential areas of the Lyon region, which have similar impermeability but different land uses, to assess how these factors influence TME distribution. Initially, stormwater runoff from both sites is broadly characterized, identifying TMEs in total and dissolved forms. This screening helps determine potential environmental risks and differences in pollution loads between industrial and residential sites. By comparing total and dissolved TME concentrations, we can assess whether these elements are bound to particles or remain in the dissolved phase, impacting their mobility and environmental risks.

Using ultrafiltration, the study further explores how TMEs are transported by separating them into different size fractions: particulate (>0.45 µm), colloidal (0.45 µm – 3 kDa), and dissolved (<3 kDa) phases. Special attention is given to the colloidal phase, which plays a critical role in adsorbing and stabilizing contaminants (Sen and Khilar, 2006). Due to their small size and large surface area, colloids are key vectors for contaminant mobility, directly influencing the fate of pollutants in urban environments.

This research contributes to the urban critical zone concept by examining TME behavior across different land uses and size fractions. It fosters interdisciplinary dialogue by addressing biogeochemical processes in urban environments and their interaction with human activities. By evaluating both total concentrations and size distribution, the study provides a comprehensive understanding of TME behavior in urban runoff, advancing efforts to mitigate environmental impacts in sustainable urban development. Through its focus on pollutant fluxes and contaminant distribution, this work supports a systemic approach to managing urban stormwater and improving water quality.

References :

Makepeace, D. K., Smith, D. W., & Stanley, S. J. (1995). Urban stormwater quality: summary of contaminant data. Critical Reviews in Environmental Science and Technology, 25(2), 93-139.

Sen, T. K., et Khilar, K. C., 2006, Review on subsurface colloids and colloid-associated contaminant transport in saturated porous media. Advances in colloid and interface science, 119(2-3), 71-96.

How to cite: Potreau, S., Blanc, D., and Gautier, M.: Characterizing Trace Metal Distribution in Urban Stormwater: Focus on Particulate, Colloidal, and Dissolved Fractions in the Lyon Metropole, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17176, https://doi.org/10.5194/egusphere-egu25-17176, 2025.

As soil artificialization and climate change continue to accelerate, effective stormwater management has become essential to mitigate flooding and preserve water resources, leading to the widespread development of stormwater management facilities based on infiltration (e.g., basins, swales, trenches, raingardens). Runoff carries suspended particles, which act as vectors for various micropollutants that can be potentially harmful or toxic to aquatic life. These facilities promote the retention of such pollutants through sedimentation and/or filtration. However, the layer of deposited sediment can, over time, impair their functioning (e.g., hydraulic regulation and contaminant mitigation). Inadequate management of sediment can thus negate the benefits of these facilities and lead to higher maintenance costs. Given the increasing implementation of stormwater infiltration facilities, accurately characterizing sediment accumulation is crucial for anticipating future maintenance needs across urban territories. However, to date, most existing methods, based on continuous measurements of flow rates and turbidity and/or stormwater sampling, are unsuitable for routine assessments across multiple sites.

This study proposes a rapid and cost-effective approach to evaluate sediment accumulation rates in stormwater infiltration facilities. The total accumulated volume over a known period is estimated by measuring sediment height along a tailored grid, combined with geostatistical interpolation. A detailed analysis of the dry bulk density of stormwater sediments, ranging from 0.4 to 1.2 g/cm³, also enables mass estimation, while knowledge of the accumulation duration allows the calculation of the average annual accumulation rate. The reliability of the method in delivering accurate estimates of the average annual particle load for urban catchments was verified by (i) comparing the results with continuous monitoring data from a pilot site over several years, and (ii) applying the method to nine sites in France and comparing the results with literature data.

Particle load estimates from this dataset showed significant variability, typically ranging from 50 to 2000 kg/ha impervious surface/year. In areas with lower sediment accumulation potential (e.g., residential areas or low-volume parking lots), loads generally do not exceed 1000 kg/ha_imp/yr, while more productive areas (e.g., high-traffic roads or heavy industrial sites) can reach up to 2000 kg/ha_imp/yr. These values can be translated into filling rates for facilities (cm/yr) by considering the degree of system centralization, defined by the ratio of infiltration area to catchment area. This rate tends to be several times higher in a centralized basin (almost 10 cm/yr) than in a source infiltration system (up to 1 cm/yr). However, spatially distributed measurements revealed heterogeneous accumulation patterns linked to hydraulic functioning, enabling targeted sediment removal as a prudent and cost-effective solution.

This approach enables the estimation of sediment accumulation rates across various urban catchments and provides an indirect method for quantifying contaminants that tend to associate with particles. Efficient in terms of both time and cost, this method supports the strategic planning of maintenance operations across diverse urban contexts, including densely populated cities and environmentally sensitive areas. By enhancing the long-term effectiveness of stormwater infiltration facilities, it helps prevent water contamination and mitigate risks to fragile ecosystems.

How to cite: Chabert, M., Tedoldi, D., Large, G., Lakel, A., Fardel, A., Lipeme Kouyi, G., Gasc, A., Nguyen, E., and Chatain, V.: A rapid and cost-effective method for assessing sediment volumes and accumulation rates in stormwater infiltration facilities, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12103, https://doi.org/10.5194/egusphere-egu25-12103, 2025.

Urban areas face increasing environmental challenges from rapid urbanization, climate change and anthropogenic pressures. These disrupt natural hydrological cycles, leading to critical problems such as rise and fall groundwater levels with a series of chained consequences. Our study applies a critical urban zone approach (Bucharest district) to start within a framework of an accurate urban groundwater balance to analyze biophysical and chemical processes in the urban environment, focusing on the Circus Lake Park in Bucharest. The site presents a complex setting shaped by decades of anthropogenic alterations, including extensive excavation, infrastructure development, and impervious surfaces that disrupt natural hydrological processes. Climate-induced changes in precipitation patterns combined with the infrastructure modifications exacerbate these challenges, reducing groundwater recharge and lowering the lake levels. By incorporating alternative water resource (AWR) solutions, our study aims to establish sustainable water management strategies tailored to the existing urban ecosystem.

The methodology integrates field experiments, laboratory analysis, and hydrological modeling to address water scarcity and pollution challenges. Infiltration tests using several methods quantified the hydraulic conductivity of heterogeneous anthropogenic urban unsaturated zone. Chemical and biological analyses of water samples from rainfall, and street runoff assessed parameters such as dissolved oxygen, heavy metals, and nutrient concentrations. An experimental filtration system comprising sand, gravel, and activated charcoal layers was designed and tested to evaluate its efficacy in treating stormwater. Hydrological and hydrogeological models were developed to simulate rainfall, runoff, and infiltration processes, enabling the assessment of aquifer recharge potential.

The results underscore the value of the critical zone approach in addressing the multifaceted challenges of urban water management. The findings reveal the effectiveness of integrating scientific methodologies with practical interventions to mitigate the impacts of urbanization and climate change. Nature-based solutions, such as stormwater filtration and aquifer recharge, demonstrate their effectiveness in adapting urban ecosystems to these pressures. Circus Lake Park serves as a replicable model, providing a blueprint for cities around the world to implement sustainable water management strategies. Beyond technical interventions, this study emphasizes the importance of interdisciplinary collaboration and stakeholder involvement. Local authorities, water operators and community organizations were actively involved, ensuring that the proposed solutions align with social, economic and environmental priorities. This collaborative approach fosters wider acceptance and ensures long-term sustainability of interventions.

The research highlights the critical importance of integrating diverse scientific, technical, and social perspectives to advance urban sustainability frameworks. By linking theoretical insights with practical applications, this study demonstrates how critical zone processes can contribute to adaptive and efficient water resource management in urban contexts. Future research should focus on scaling these strategies and evaluating their long-term ecological and social impacts to further inform global urban resilience efforts.

How to cite: Luca, O., Moraru, I., Ghibus, T., Zonouzi, O., Miller, M., Gogu, R., Gheorghe, A., and Demianovschi, V.: Exploring Critical Zone Processes for Sustainable Water Management: The Case of Circus Lake Park, Bucharest, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-21779, https://doi.org/10.5194/egusphere-egu25-21779, 2025.

In urban areas, water bodies provide a number of ecosystem services that are particularly crucial: flood control, preservation of biodiversity, formation of cool islands, recreational activities, landscape quality, etc.

Lakes and ponds are part of the urban critical zone. Many of them have been created in the recent decades as sand-pit lakes or retention ponds. Sand-pit lakes are the result of sand and gravel extraction for the construction of towns. Retention ponds have been implemented to limit flooding risks and to reduce the pollution peaks associated with heavy rainfall. Actually, in the context of climate change, urbanisation which is associated with the imperviousness of soils, increases the run-off processes.

Moreover, the large interface between the aquatic and terrestrial environments makes these urban lakes fundamental ecosystems for maintaining biodiversity in the city.

The hydrodynamics, ecological functioning and fate of contaminants in the water column of these lakes are very important environmental issues. In order to better understand the physical and biogeochemical processes at stake and to which extent they may be affected by climate change, autonomous monitoring stations can provide long-term, high-frequency, reliable datasets. These data are also very useful for the calibration of numerical model parameters.

The monitoring station implemented in Lake Creteil, in a highly urbanised area of the Greater Paris region (France) is presented. The surface area of the lake is 0.4 km², average depth 4 m, maximum depth 6 m. The lake is fed by groundwater flowing from the Marne to the Seine and by the stormwater network of an urban catchment (1 km²). This observation platform is part of an OSU (Observatoire des Sciences de l’Univers) and is also associated to the French SNO OBSERVIL (Service National d’Observation) network.

The instrumented buoy is equipped with underwater probes to measure physical and biogeochemical parameters and a weather station. Underwater measurements are performed every 15 minutes and meteorological measurements every 10 minutes. Temperature probes (CS225 Campbell) are deployed at five different depths: 0.5 m, 1.5 m, 2.5 m, 3.5 m and 4.5 m. At 1.5 m depth, a multiparameter probe (YSI Exo3) measures oxygen, conductivity, chlorophyll-a and phycocyanin. The weather station measures the wind speed and direction, air temperature, relative humidity, atmospheric pressure, rainfall height, short and longwave radiations.

The lake data are exported to a local database via a GSM protocol. The data is visualized on a web dashboard using the open-source Grafana software. On the dashboard, the timeseries of the underwater and the meteorological measurements are displayed in a panel and the short-term (2 days) forecast of the variables obtained by a neural network model are plotted as gauge charts.

The results of the timeseries analysis are presented to illustrate how some physical and biogeochemical processes occurring in the lake (e.g. thermal stratification, peak of phytoplankton biomass, anoxia of the deep layers…) have been quantified. The use of the data for parameter calibration and validation of hydro-ecological numerical models is also presented.

How to cite: Vinçon-Leite, B., Cartier, Y., Guillot – Le Goff, A., Marquet, A., Saad, M., and Dubois, P.: Improving the understanding of the functioning of water bodies in the urban critical zoneAn observation platform of an urban lake in the Greater Paris region, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11927, https://doi.org/10.5194/egusphere-egu25-11927, 2025.

Abstract

Microplastics (MPs) contamination is a global and pervasive problem in the riverine ecosystem, where rivers serve as conduits, transporting microplastics from land-based sources to the ocean. MPs transport is influenced by physical characteristics and hydrodynamics, with high-density MPs likely to be near riverbeds, while low-density particles float over river surfaces. The transport of MPs occurs either due to settling (horizontal transport) or gravity-driven (vertical transport). This study investigates the intricate relationships between sediment transport, hydrological processes, and the behavior of various MPs, with a particular focus on their vertical and horizontal migration in riverine environments. Additionally, the study highlights how the physicochemical properties of MPs influence their transport within these systems. Several removal methods have been developed to mitigate microplastic pollution, including coagulation/sedimentation, adsorption, ultrafiltration, biodegradation, and photocatalytic degradation. These techniques have proven effective in eliminating microplastics composed of polymers such as polystyrene (PS), polyethylene (PE), and polyethylene terephthalate (PET). Among the solutions, biochar and microbial agents stand out as promising, eco-friendly alternatives. Therefore, this study also emphasizes the importance of the development of effective removal of MPs to protect aquatic ecosystems.

Keywords: Microplastics; Riverine; Ocean pollution; Vertical; horizontal movement

How to cite: Bahukhandi, K. D., Arya, S., Kamboj, N., and Dogra, K.: Microplastic Pathways: Investigating Vertical and Horizontal Movement from Riverine Environments to Oceans, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10888, https://doi.org/10.5194/egusphere-egu25-10888, 2025.

Biocides are used extensively in urban settings for façade coatings, roof waterproofing, and termite control. During rainy weather, they are released into building runoff, causing negative impacts on aquatic and terrestrial ecosystems. Prior studies mainly focused on laboratory experiments or small-scale contexts. Urban-scale modeling, however, has rarely been explored. This is due to the complexity of biocide behavior, the spatiotemporal variability of emission factors, and the limited knowledge about biocide use and existing stocks within the urban critical zone. Our objective is to assess the stock potential and emission potential of biocides from building envelopes in the Parisian conurbation. We also aim to develop and implement a model at the urban scale to evaluate the fluxes of biocides emitted in runoff water from building facades. One of the main factors that significantly influences the emissions is the wind-driven rain (WDR), which directly affects the volume of water runoff on building facades. Since emissions strongly depend on WDR, precise modeling needs adequate meteorological data, especially for extensive metropolitan regions. Our research focuses on the Île-de-France region, a heterogeneous and extensive urban area. This study examines the variability in meteorological data—namely precipitation, wind speed, and wind direction from nine stations located across the area (Acheres, Le Bourget, Longchamp, Magnanville, Orly, Paris Mont-Souris, Roissy, Trappes, and Villacoublay). By analyzing the data from these stations, we seek to quantify the variability in meteorological conditions across the area; evaluate the influence of these variations on cumulative biocide emissions; and assess the potential enhancement of accuracy and reliability in emission estimations by the combination of data from various stations.

To estimate biocide runoff from facades, we will develop scenarios on COMLEAM, a software program created by HSR (Hochschule für Technik Rapperswil) that simulates the leaching of hazardous compounds from building materials subjected to environmental conditions. The scenario used considers a building with eight façades oriented in primary compass directions made of render matte containing encapsulated terbutryn. Leaching behavior is approximated using mathematical functions from experimental data. As our investigation will not include an experimental component, we will depend on those suggested by COMLEAM, particularly the logarithmic function, which has been shown to be the most effective for characterizing biocide emissions. The emission function applied for terbutryn follows a logarithmic relationship derived from field studies in Zurich.

The findings demonstrate WDR's strong effect on biocide emissions, with important variation between measurements of each station. Two extremes were identified: Roissy had the highest cumulative WDR (200 L/m² from South-West) and emissions (~11,000 mg), whereas Acheres had significantly lower WDR (70 L/m² from South-West) and emissions (~7,000 mg). The others had comparable findings, with a total WDR of 140 L/m² and emissions of 10,000 mg over 10 years. These results also highlight the importance of the measurement station's location, as open-space stations (e.g., Roissy) exhibited higher WDR due to reduced shielding. From this study, we deduce that using large-scale meteorological data introduces biases, making meteorological parameter refinement essential for improving accuracy.

How to cite: Saad, R., Gromaire, M.-C., Bressy, A., Katia, C., and Ghassan, C.: Variability of Biocide Emissions from Building Facades Based on Meteorological Data, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13816, https://doi.org/10.5194/egusphere-egu25-13816, 2025.

The extensive use of aqueous film-forming foam (AFFF) at US military facilities has led to significant contamination of poly- and perfluoroalkyl substances (PFASs) of the subsurface. So far, PFASs contamination at firefighting training areas (FTAs) has been mostly studied in groundwater and soil, neglecting the contribution of leaching from PFASs-contaminated construction materials such as concrete and asphalt into the adjacent environment. Previous studies measured PFASs concentrations reaching up to mg/kg in concrete and asphalt at FTAs and leaching substantial levels (up to μg/L) into runoff water.

Our study investigates the PFASs leaching behavior from AFFF-impacted construction materials, focusing on concrete and asphalt sourced from military sites. The primary objectives include evaluating PFAS leaching rates and duration under various weathered and stabilizer-treated conditions and assessing the effectiveness and potential longevity of reforming techniques and sorbent materials in mitigating PFAS contamination in surface runoff. These data are critical for estimating stormwater treatment lifecycle costs and comparing treatment with other remedial alternatives, such as excavation and disposal. Dynamic rainfall simulations were conducted on intact PFAS-contaminated cores to replicate field conditions. Preliminary results indicate that biochars hold significant potential as sorbents when integrated into concrete formulations, effectively adsorbing PFASs and improving the concrete matrix. Additionally, we hypothesize that rainfall contact time on concrete and asphalt surfaces plays a critical role in influencing PFAS concentrations, a hypothesis which will be tested through both laboratory experiments and modeling efforts. To support this, a funnel prototype was developed to assess the effects of slope and contact time on PFAS leaching profiles. These findings provide important insights into PFAS leachability under varying conditions and highlight the environmental implications of reusing PFAS-impacted construction materials across various industries, including PFAS manufacturing and chrome plating.

The results underscore the critical need for additional leaching experiments to advance sustainable reuse practices for PFAS-impacted construction materials. Such efforts are essential for developing cost-effective source control strategies and lifecycle comparisons to inform broader remediation frameworks in both military and industrial applications.

Keywords: PFASs-impacted construction materials, Leaching behavior, Dynamic rainfall simulation, Concrete and asphalt reuse, Sorbent materials.

How to cite: Hamidi, F., Sharma, A., Fries, E., Mueller, J., Thai, P., Jekimovs, L., Fiorenza, S., Toth, K., Steets, B., Ervin, J., Tunstall, L. E., and Higgins, C. P.: Leaching of PFASs from PFAS-Impacted Construction Materials: An Experimental and Modeling Study, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13211, https://doi.org/10.5194/egusphere-egu25-13211, 2025.

Rivers and streams worldwide are increasingly impacted by emerging organic contaminants (EOCs) as a result of wastewater treatment plant (WWTP) effluents discharges and human and industrial activities. Within this context, the hyporheic zone (HZ), which is the interface between surface water and groundwater, is often regarded as a critical compartment for EOCs attenuation. This is due to processes such as sorption onto soil organic and mineral phases, as well as biotransformation mediated by the diverse microbial communities present in such environments. However, the distinction between these two attenuation pathways is frequently hindered by the highly variable hydrochemical conditions encountered in field studies. To address this issue, we conducted a series of laboratory experiments designed to replicate the natural conditions of the HZ of a heavily polluted stream in the Hessian Ried, Germany.

The experimental setup consisted of a set of three different column experiments, each performed in triplicate. To achieve this, we collected nine undisturbed soil cores of 25 cm from the riverbed of the Landgraben, a stream impacted for decades by industrial and domestic WWTP effluents. The experiments differed in the feeding solution. For the first set of columns, we used real river water, collected every two weeks, stored refrigerated and replenished every three days to avoid changes in chemical composition. For the second group we spiked the inflow water with a cocktail of five pesticides not detected in the river water but commonly used in the area for pest control, to investigate their fate in the HZ. Finally, for the last set of triplicates, we used tap water free of EOCs as inflow water to characterize desorption processes. Samples were regularly collected from the inflows and outflows of all columns to generate breakthrough curves of EOCs over a total duration of 300 pore volumes, with flow rates adjusted to replicate residence times observed in the field. A total of 28 EOCs were analyzed using LC-MS/MS, covering a broad spectrum of physicochemical properties, including ionic speciation and polarity, which are key factors controlling the fate of EOCs in soils.

Our results showed that many of the analyzed compounds are highly mobile in the HZ and not attenuated. This is attributed in some cases to high polarity (e.g., candesartan, gabapentin, hydrochlorothiazide, valsartan acid) and in others to the saturation of sorption sites (e.g., metoprolol, sitagliptin). Only a few compounds exhibited evidence of transformation (e.g., diatrizoic acid, iopromide, sulfamethoxazole). Compounds with medium polarity and with negative or neutral speciation were slightly attenuated, primarily through sorption (e.g., carbamazepine, diclofenac, irbesartan, 1,2,3-benzotriazole). Overall, our findings suggest that the HZ of a long-term polluted stream is capable of mitigating only a small fraction of EOCs, posing a significant risk to surface and groundwater bodies.

How to cite: Muñoz-Vega, E., Bockstiegel, M., Abdighahroudi, M. S., Ihle, K., Richard-Cerda, J. C., Bertold, C., Yin, M., Reusing, M., Lutze, H., Schüth, C., and Schulz, S.: Fate of emerging organic contaminants in the hyporheic zone of an anthropogenically impacted stream, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19071, https://doi.org/10.5194/egusphere-egu25-19071, 2025.

Wastewater treatment plants (WWTPs) are major contributors to the release of volatile organic chemicals (VOCs), many of which pose significant risks to human health through both non-carcinogenic and carcinogenic pathways. These chemicals, along with plastic-derived compounds, pesticides, and pharmaceuticals and personal care products (PPCPs), have emerged as critical environmental pollutants. Their widespread release through urban wastewater systems, combined with their hydrophilic nature and limited removal efficiency in conventional WWTPs, allows these pollutants to persist throughout the water cycle, often contaminating drinking water supplies. Despite increasing global awareness of the environmental and health risks associated with these contaminants, data on their occurrence, transport, and fate in Mexico's wastewater systems are still limited. To address this knowledge gap, the present study analyzed 54 VOCs in wastewater samples collected from 17 WWTPs across different provinces of Mexico. Among these, 38 VOCs were detected at significant levels, with the highest concentrations recorded for Toluene (21.39 µg/L), 1,1,2,2-Tetrachloroethane (28.02 µg/L), followed by p-Isopropyltoluene (27.24 µg/L), and Trichloromethane (17.56 µg/L). Additionally, pesticides and related chemicals such as 2-Chlorotoluene, Naphthalene, 1,2-Dichlorobenzene, and n-Butylbenzene were prevalent, underscoring the extensive use of these compounds in agricultural practices. These chemicals not only bioaccumulate in soil but can also leach into groundwater systems, exacerbating contamination risks and increasing their persistence in the environment. Furthermore, many of the detected compounds, such as Toluene, its derivatives, and Trichloromethane, are known endocrine disruptors (EDCs) capable of causing hormonal imbalances, drug resistance, and reduced primary productivity in ecosystems. Their bioaccumulation in organisms and persistence in water further exacerbate their environmental impact, making them critical candidates for regulatory scrutiny. Therefore, this study underscores the urgent need for enhanced regulatory monitoring and management strategies targeting VOCs and EDCs in Mexico’s wastewater systems. By providing valuable insights into the prevalence and distribution of these hazardous pollutants, the findings highlight the importance of incorporating pesticides and PPCPs into comprehensive monitoring frameworks. Such efforts are essential for mitigating the environmental and health impacts of these contaminants and ensuring the sustainable management of water resources. The results also offer a foundation for developing targeted interventions aimed at reducing pollutant loads in wastewater and preventing their long-term accumulation in aquatic ecosystems.

How to cite: Gupta, P., Dogra, S., Dash, S., and Kumar, M.: Tracking Volatile Organic Compounds in Urban Wastewater Systems: A Critical Concern for Endocrine Disruptor Regulation, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8456, https://doi.org/10.5194/egusphere-egu25-8456, 2025.

Soil aquifer treatment (SAT) using secondary treated wastewater effluent (STWW) as infiltration feedwater is an increasingly discussed measure to mitigate groundwater level decline. It may also act as an additional treatment stage for the attenuation of emerging organic compounds (EOCs), e.g., pharmaceuticals and industrial agents, which STWW effluent still contains in varying amounts. Hence, understanding the behaviour of EOCs in SAT systems, both in the unsaturated and saturated zone, prior to implementation and operation, is of high importance. For that purpose, sand tank experiments are one possibility to study under controlled conditions the attenuation potential of natural and amended soils with e.g., permeable reactive layers.

Therefore, we designed and built novel large-scale sand tank experiments, consisting of three individual, L-shaped, tanks made from HDPE (Horovitz et al., 2024). All three tanks were packed with fine-medium quartz sand. The vertical part acts as unsaturated infiltration zone. The horizontal part consists of a saturated zone with continuously flowing groundwater in the lower part and an unsaturated zone above. The infiltration zone of two tanks were amended with one reactive layer each (biochar and compost, both mixed with the fine-medium quartz sand). The third tank acted as reference without reactive layer. Native groundwater from LNEC campus was used for continuously laterally flowing groundwater. The feedwater was a real STWW effluent from a Lisbon wastewater treatment plant. The groundwater flow rate was set to achieve a retention time of approx. one month for the STWW inside the tanks. In total, six infiltrations were performed over approx. eight months. Our setup allowed us to take samples both in the unsaturated and saturated zones. Additionally, the tanks are equipped with high-resolution oxidation-reduction potential sensors, both in vertical and horizontal direction, being an important parameter for the degradation of some EOCs.

Our results showed that for the tank setup, amended with a biochar layer, all 22 EOCs were fully attenuated, while for the tank containing a compost layer 14 EOCs (1,2,3-Benzatriazole, 4,5-Methyl Benzatriazole, Amisulpride, Atenolol, Carbamazepine, Cetirizine, Ciprofloxacin, Diclofenac, Hydrochlorothiazide, Iopromide, Irbesartan, Metoprolol, Sitagliptin, and Venlafaxine) were attenuated with varying percentage. In contrast, for the reference tank, only a decrease of eight EOCs (Amisulpride, Atenolol, Ciprofloxacin, Iopromide, Irbesartan, Metoprolol, Sitagliptin, and Venlaflaxine) could be observed.

Our results show that the implementation of tailored permeable reactive layers in SAT systems could substantially improve the quality of STWW during infiltration regarding EOCs, leading to a greater confidence in applying this technology.

References

Horovitz, M., Muñoz-Vega, E., Knöller, K., Leitão, T.E., Schüth, C., & Schulz, S., (2024). Infiltration of secondary treated wastewater into an oxic aquifer: Hydrochemical insights from a large-scale sand tank experiment. Water Research 267, 122542. https://doi.org/10.1016/j.watres.2024.122542

How to cite: Horovitz, M., Muñoz-Vega, E., Abdighahroudi, M. S., Leitão, T. E., Schüth, C., and Schulz, S.: Behaviour of 22 emerging organic compounds from secondary treated wastewater effluent in soil aquifer treatment – Assessing the attenuation potential of biochar and compost reactive layers in a large-scale sand tank experiment, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20034, https://doi.org/10.5194/egusphere-egu25-20034, 2025.