Landfill leachate circuits that operate without discharge, by recirculating aerated leachate onto the waste mass, are widespread in South-East Europe, yet their long-term behaviour is rarely documented with sample-level data. This study reports a six-year (2020–2025) seasonal monitoring campaign at a sanitary landfill in northern Serbia (alluvial aquifer of the Sava River, transboundary Danube basin) and re-examines it with a transparent multivariate protocol. Seventy-two leachate samples (collection well, aeration lagoon, sedimentation lagoon; n = 24 each, 30 parameters), 28 realised surface-water campaigns, and six years of groundwater summaries were evaluated by principal component analysis/factor analysis (PCA/FA, Varimax normalized), hierarchical cluster analysis, PERMANOVA, non-parametric paired tests and, for benchmarking, supervised machine learning. The pooled leachate model (n = 72; 21 variables; KMO = 0.700; Bartlett χ2 = 956, p < 0.001) retained four factors by parallel analysis, explaining 61.6% of total variance; after rotation the factors accounted for 27.7%, 14.3%, 10.4%, and 9.3%. Factor 1 grouped organic load with particle-reactive metals (COD, BOD5, Fe, Ni, Cr, As, Zn), Factor 2 a reduced sulfur–fluoride–BTEX signature, Factor 3 temperature-driven nitritation, and Factor 4 a nitrate–manganese redox contrast. Crucially, paired campaign-by-campaign comparison showed no removal of the dominant pollutants along the circuit. Median COD, BOD5 and NH4-N were not lower in the sedimentation lagoon than in the collection well, while pH rose from 8.08 to 8.75 (p < 0.001); only Cu, Pb, NO3-N, and NO2-N decreased significantly. The circuit therefore homogenises and concentrates dissolved load rather than removing it. Downstream surface water was significantly enriched in electrical conductivity (+110 µS/cm), total dissolved solids, NH4-N, and NO2-N relative to upstream (Wilcoxon, p < 0.05), and groundwater showed episodic conductivity up to 12,760 µS/cm and NH4-N up to 102 mg/L. Cytotoxicity (MTT) confirmed biological relevance, with MRC-5 viability falling to 37% after 24 h exposure to 50 vol.% groundwater (Pw3) versus 60% in A549 cells. A random-forest classifier separated circuit units far better than PCA-based discrimination (76.4% versus 54.2% cross-validated accuracy) and distinguished the 2020–2021 pandemic period from 2022–2025 with 94.2% accuracy, a period effect also confirmed by PERMANOVA (R2 = 7.2%, p < 0.001). The results indicate that closed-loop recirculation without an engineered discharge barrier transfers, rather than eliminates, contaminant load, and that after-care of such systems requires mass-balance monitoring and polishing treatment.
Managed aquifer recharge (MAR) with stormwater remains underexplored in rural settings due to uncertainties related to source-water variability, treatment performance, and groundwater-quality impacts. This study presents the design and hydrogeochemical evaluation of a stormwater-based MAR pilot site implemented in 2024 in Hüll (Bavaria, Germany), a flood-prone agricultural region underlain by a heterogeneous Tertiary aquifer. The system integrates a stormwater retention basin, treatment units, an infiltration well, and a comprehensive monitoring framework combining multi-parameter online sensors, detailed laboratory analyses, and contextual information on catchment activities. Hydraulic testing confirmed strong aquifer heterogeneity but also demonstrated high injectivity of the target formation. Hydrochemical monitoring evaluated raw water characteristics, treatment efficiency, and groundwater responses. The treatment unit effectively removed pesticides and substantially reduced suspended solids, while stormwater nitrate concentrations were consistently lower than those in groundwater, indicating dilution potential during recharge. The pilot demonstrates that rural stormwater can serve as a reliable MAR source under variable hydrological conditions. The integrated design and monitoring concept provides a transferable framework for similar agricultural regions and supports future calibration of site-scale hydrogeological and reactive transport models.
Lea Augustin, Teresa Jansen, T. Baumann· Hydrogeology Journal· 0 citations
Rapid urban growth in India has led to a surge in construction and demolition (C&D) waste, much of which is disposed of without regulated management. In Bhopal, Madhya Pradesh, unauthorized dumping near the shoreline of the Upper Lake a primary source of potable water poses a severe risk of leachate contamination. This study investigated the hydro-chemical impact of C&D waste through a year-long monitoring program across georeferenced impact sites. Data were evaluated using descriptive statistics, one-way ANOVA, and Pearson correlation, while Principal Component Analysis (PCA) was employed to identify dominant pollution sources and the "Source-to-Impact" pathway. The results reveal an environment under acute anthropogenic stress, with a singular "C&D Impact Factor" (PC1) explaining over 99% of the total variance in both physicochemical and heavy metal datasets. Critical physicochemical shifts included extreme alkalization (pH: 8.5-11.5; Mean: 10.0), elevated turbidity (100.07-399.93 NTU), and high Total Dissolved Solids (500.17-1199.83 mg/L). High BOD levels (8.01-49.99 mg/L) coincided with a significant decline in Dissolved Oxygen, indicating a shift toward a hypoxic state (r = -0.988). Hazardous heavy metals, including Aluminum (0.5-1.5 mg/L), Lead (0.025-0.045 mg/L), and Chromium (0.050-0.100 mg/L), exhibited perfect synchronization with structural minerals (Ca, Mg), confirming a unified leaching mechanism from cementitious debris. Mechanistic interpretation suggests that hyper-alkaline conditions facilitate the mobilization of amphoteric metals and the degradation of sequestering gels. These findings highlight substantial ecological risks and long-term bioaccumulation threats, emphasizing the urgent need for strict C&D waste regulatory enforcement and sustainable water resource management to preserve the integrity of urban freshwater ecosystems.
Anupam Sharma, S. Bhadauria, Amit Vishwakarma· Scientific Reports· 0 citations
Water quality in high-elevation agricultural river valleys is shaped by regional environmental gradients and localized hydrogeochemical conditions, but multi-year assessments often do not clearly separate routine hydrochemical variability from metal(loid) risk. This study evaluates a public multi-year dataset from the agricultural concentration area of the Yarlung Zangbo River and its two tributaries on the Qinghai–Tibet Plateau. The dataset includes 444 river-water, groundwater, and irrigation-water samples collected in 2019, 2020, 2021, 2023, and 2024. We combined water-type-specific standard assessment, normalized exceedance frequencies, spatial visualization, and descriptive correlation analysis with terrain, land-cover, soil, and climate-hydrological predictors. Because sampling coverage and hydrological-period classification differed among years, annual contrasts were interpreted descriptively rather than as fixed-site temporal trends. Most samples were neutral to weakly alkaline, whereas electrical conductivity (EC), total dissolved solids (TDS), and salinity varied more strongly across years and sampling locations. In total, 70 samples exceeded at least one evaluated criterion, but only 12 samples were flagged in the metal(loid) assessment. Eight samples exceeded the 0.05 mg/L As screening threshold, occurring only in 2023 and 2024 (3.25% and 2.92% of samples in those years, respectively), and were concentrated in a localized reach rather than distributed basin-wide. As was positively associated with Mo and Hg, whereas relationships with Fe, Mn, pH, EC, TDS, and salinity were weak or inconsistent; dissolved oxygen was not available for the high-As samples. These results distinguish broad dissolved-solute variability from localized As-dominated risk and show that the dataset supports regional screening and monitoring prioritization, but not definitive redox, speciation, or source-apportionment conclusions.
Landfill leachate is a highly charged and complex wastewater whose composition changes significantly with landfill age, typically categorized into young, intermediate, and mature types. In the specific case of Oujda Morocco, leachate management is further complicated by a waste typology characterized by a high organic fraction (74.2%) and high moisture content (64.4%). These conditions generate extremely strong leachates with elevated concentrations of chemical oxygen demand (COD), ammonium, and total dissolved solids (TDS), representing a severe threat to regional water resources. Because single-stage conventional methods are no longer adequate to meet stringent environmental discharge standards, the recourse to integrated chemical-physical-biological processes is essential. The study aims to provide a comprehensive overview of landfill leachate classifications and their basic physicochemical characteristics; to introduce treatment technologies implemented globally and emphasizes the imperative of hybrid systems for managing highly concentrated effluents such as those produced in the Moroccan landfills. Furthermore, the research outlines a future study dedicated to optimizing an eventual combined treatment train specifically for the unique characteristics of Oujda's leachate.
Ikram Messaoudi, Y. Regad, F. Boushaba· EPJ Web of Conferences· 0 citations
This study evaluates the operational efficiency of Managed Aquifer Recharge (MAR) systems utilizing open-type infiltration structures in the Koksu District of Southeastern Kazakhstan. Field investigations conducted between 2022 and 2024 characterized the filtration hydrodynamics and mechanical clogging kinetics within the vadose zone and the underlying gravel–pebble aquifer. Our methodology integrated the use of local surface water and groundwater to provide a high-resolution assessment of recharge performance under authentic hydrogeological conditions. The results demonstrate a significant, multi-stage degradation of infiltration capacity, primarily driven by mechanical clogging. Initial infiltration rates (12.0–6.0 m/day) underwent a sharp decline to 4.1–2.0 m/day within 92 days of operation, eventually plateauing at a critical minimum of 0.8 m/day. This reduction correlates with the accumulation of an 11 mm fine-grained sediment layer, induced by surface water turbidity (18–38 mg/dm
3
), resulting in a six-fold reduction of the infiltration coefficient. Concurrently, MAR operations facilitated a maximum groundwater rise of 3.1 m, while total dissolved solids (TDS) of groundwater were effectively halved through freshwater dilution, significantly improving water quality. Economically, the implementation of the MAR system increased regional water availability by 20–25%. These findings establish that while the unconfined aquifers of the Koksu Basin possess high potential for seasonal storage, their long-term viability is contingent upon systematic mechanical regeneration. This research provides a robust technical framework for MAR deployment to support livestock watering and sustainable pasture irrigation in arid Central Asia.
A. Ismagulova, T. Rakhimov, V. Kulagin et al.· Frontiers in Water· 0 citations
Engineered landfills remain a prevalent municipal solid waste (MSW) disposal method, designed and operated to minimize environmental impacts such as methane (CH4) emissions and leachate production. This study compares the effectiveness of two cover systems in minimizing emissions: geomembrane (GM) and compacted clay liner (CCL) in MSW landfills in Poland and the Czech Republic. Using the Hydrologic Evaluation of Landfill Performance model, six scenarios quantified leachate generation and sealing efficiency. Results showed that GM covers reduced the volume of leachate by up to four times compared to CCL (avg. 141.2 m3 ha-1). Analysis of landfill gas (LFG) monitoring data indicated a significant discrepancy in CH4 emission pattern for CCL ranging from 0.3% to 66.5% of LFG volume, suggesting thatGM covers are more effective in mitigating the emission of greenhouse gas via more organized emissions. The findings address the current gaps in international regulations and support more sustainable landfill closure practices aligned with the European Union Policy and sustainable development goals.
Aleksandra Jakimiuk, M. Vaverková, A. Podlasek et al.· Waste Management Research· 0 citations