Climate change and global warming are increasingly affecting freshwater bodies both locally and globally, resulting in fluctuating water levels. Understanding how Cladocera communities are organized across different water body types is important for ecological assessment and conservation. In this study, we compared Cladocera assemblages between different wetland types with different water body types and evaluated the role of physicochemical characteristics and spatial structuring in shaping the community distribution patterns. Six water bodies were selected for our study; each contained three sampling points spaced at least 75–100 m apart. Cladocera specimens in the filtrate samples were identified at the species level. Homogeneity of multivariate dispersions (PERMDISP) and PCA analysis of site-related spatial effects were used to test differences in community composition. Based on previous studies and results, we concluded that the water body type significantly influenced the composition of Cladocera communities among the wetlands investigated.

The role of on-site wastewater treatment (OSWT) is increasingly important for water reuse and local sustainability, but treatment efficiency is highly dependent on hydraulic behavior and mixing. This study used validated CFD simulations and tracer experiments to analyze flow patterns and mixing performance in a six-zone OSWT unit under different operational scenarios, including inflow, aeration, recirculation, combined mechanisms, and closed-loop operation without inflow. The results show that influent flow is essential for maintaining convective transport and system-wide momentum, while aeration and recirculation enhance local mixing, but cannot fully overcome geometric dead zones. The combined use of inflow, aeration, and recirculation achieved the highest mixing efficiency and minimized the dead volume, whereas scenarios lacking inflow exhibited severe stagnation and expanded dead zones. These findings highlight the need to integrate hydraulic interventions with thoughtful reactor design to ensure effective and resilient small-scale wastewater treatment systems.

A fenntartható és biztonságos települési vízellátás érdekében a hálózatok hidrodinamikai szempontú elemzése elengedhetetlen. A fogyasztási pontok térbeli elhelyezkedése és a fogyasztás időbelisége (menetgörbék) meghatározza a hálózaton belüli nyomásviszonyokat. Ennek segítségével a hálózati kritikus pontok (például a csőtörés veszélye a nagy hálózati nyomás miatt vagy a nagy tartózkodási idejű zónák) azonosíthatók, a beavatkozási lehetőségek ki­dolgozhatók. A hidrodinamikai modell jósága annak felbontottságától alapvetően függ. A valós viszonyokat leképező, földrajzi információs rendszereken (Geographic Information System, GIS) alapuló geokódolt topológiai modellel a fogyasztási arányszámok meghatározhatók, és a modellezési cél elérhető. A tanulmányban több lehetőséget körüljárva a legmegfelelőbb stratégiát dolgozzuk ki, amelynek során a vízforgalom meghatározható.Kulcsszavak: vízellátó hálózat, geokódolás, hidraulikai modellezés, GIS, EPANET Improving the Hydrodynamic Efficiency of Water Distribution Networks Based on Geocoding StrategiesA hydrodynamic analysis of the networks is crucial for a sustainable and safe urban water supply. The spatial distribution of consumption points and the variation of consumption over time (‟water demand curves”) determine the pressure relationships within the network. This allows the identification of critical points in the network (e.g. risk of burst pipes due to high network pressure or zones with high residence times) and the development of intervention options. The accuracy of the hydrodynamic model depends essentially on its resolution. With a geocoded topological model based on GIS techniques, which represents real conditions, consumption rates can be determined and the modelling objective achieved. The study explores several options to develop the most appropriate strategy to determine the water flow.Keywords: water supply network, geocoding, hydraulic modelling, GIS, EPANET

Geospatial tools and geocoding systems play an increasingly significant role in the modernization and operation of municipal water utility networks. This research explored how geocoding systems could improve network management, facilitate leak detection, and enhance hydraulic modeling accuracy. Various geocoding services, including Google, Bing Maps, and OpenStreetMap APIs were analyzed using address data from a small Central European municipality. The analysis was performed in February and March of 2024. The accuracy and efficiency of these systems in handling spatial data for domestic water networks were assessed and results showed that geocoding accuracy depended on the quality of the service provider databases and the formatting of input data. Google proved the most reliable, while Bing and OpenStreetMap were less accurate. Additionally, the Location Database developed by Lechner Knowledge Center was used as a reliable local reference for comparison with global services. Geocoding results were integrated into GIS softwares (Google Earth ver. 7.3.6.9796, QGIS ver. 3.36, ArcGIS ver 10.8.2) to enable spatial analysis and comparison of geographic coordinates. The findings highlight geocoding’s critical role in efficient water network management, particularly for mapping consumer data and rapidly localizing leaks and breaks. Our findings directly support hydraulic modeling tasks, contributing to sustainable operations and cost-effective interventions.

Benzene, toluene, ethylbenzene and xylenes, collectively known as BTEX compounds, are significant emerging contaminants in municipal wastewater. Stricter effluent quality regulations necessitate their removal, especially with concerns about organic micropollutant concentrations. Water scarcity further underscores the need for wastewater treatment to ensure safe agricultural or drinking water supplies. Although biological treatment partially reduces BTEX levels through processes like biodegradation and sorption, additional purification using physico-chemical methods is crucial for substantial reduction. This paper aims to outline plant-wide simulation methods for treating BTEX-contaminated sewage and facilitating reuse, adhering to IWA Good Modelling Practice Guidelines. The model, built upon the MiniSumo process model, incorporates equations detailing BTEX metabolism and removal kinetics, informed by an extensive literature review. Using a variant of the Benchmark Simulation Model with granular activated carbon for water reuse, the study examines strategies for improving effluent quality and minimizing operational costs. These strategies include adjusting the sludge retention time and airflow to enhance BTEX degradation and stripping, respectively, and comparing maintenance approaches for the GAC tower.

Water utilities are like arteries for the urban environment and, in order to satisfy water demand, extensive design and operation work applying modeling tools is required. An effective tool can be operated but only if the input, such as real-world consumption data, is built into the system. This study aims to present a GIS-based technique to align the consumption data to a simplified network topology. This study investigates four distinct methods, revealing noteworthy outcomes. The geocoding of consumption locations facilitates their seamless integration with model nodes through geospatial methods. Additionally, effective water consumption allocation is achieved by delineating influence ranges around each node. When comparing the zoning based on the street approach and the arithmetic average with the benchmark manual range of influence approach, substantial errors appear of approximately 190% and 230%, respectively. Addressing the impracticality of the manual method, especially for larger networks, this study advocates for the use of Thiessen polygons to delineate influence areas. In conclusion, this study presents a holistic approach to aligning consumption data with simplified network topologies for enhanced water utility modeling.

Studies on the sediments of lakes with varying trophic status are of particular importance when considering changes in the natural environment. In this study, our objective was to examine subfossil remains of Cladocera species and the relationship between the sedimental Cladocera assemblages and geochemical variables during 11 years of sediment records from northern Hungarian lakes. To achieve this, we compared sedimental cladoceran communities and the geochemistry of the sediment layers among lakes. Among the studied lakes, one was an intermittent lake (KMT: the Kis-Morotva Lake) which dried out in 2012 but was subsequently naturally refilled in 2013 by groundwater affected by the high-water level of the River Tisza. The other type consisted of permanent lakes (SZA: the Szabolcs oxbow lake, TI: the Timár Morotva Lake) that never dried out. The results of the beta diversity analysis show that the deposition of Cladocera communities was similar among the sediment layers of lakes, while the abundance differences contributed significantly to replacement. Subsequently, core sediment samples of the three lakes were compared based on the remains of Cladocera communities and geochemical variables using Adonis (PERMANOVA). The core sediment samples indicate variations in Cladocera communities alongside disparities in geochemical variables across the same lakes. In conclusion, the significance of sediment cores containing the remains of the Cladocera community has grown significantly in the reconstruction of historical ecological and climatic changes.

In the contemporary era, with rapid industrial growth and urbanisation, analysing the impact of human activities on soil enzyme activity becomes crucial. The purpose of this study is to assess the influence of anthropogenic pollution on enzyme activity in soil. Research on enzyme activity levels in the soil in the city of KaraBalta, Chuy Region, Kyrgyz Republic, was conducted using biochemical analyses and specific enzymatic tests. The results revealed significant diversity in catalase activity in different soil samples. Some samples exhibited high activity, while others showed low activity. These differences may be associated with oxidative stress and the ability of soil microorganisms to decompose hydrogen peroxide. Urease analysis indicated the highest activity in soil samples after 2 hours, particularly near the protective barrier of the tailings pond, suggesting intensive chemical reactions, especially near pollution sources. Research has also revealed the diversity of protease activity in soil ecosystems, where samples with high activity may more effectively break down proteins compared to samples with low activity. To achieve ecological stability of soil resources, it is necessary to develop a management strategy, including monitoring and restoring priority areas considering local characteristics, supporting biodiversity, applying sustainable agricultural methods, and combating soil erosion. Important steps also include forming a community emphasising the importance of soil resources, funding research, and collaborating with local authorities, scientists, and the business community. The results of the study can be used in developing strategies to prevent the negative consequences of soil pollution, contributing to improved ecological resilience, especially for environmental protection agencies

Lamellar settlers are widely used in solid separation due to their relative high surface area paired with a small tank volume. Settlers exposed to high load variations may change their settling properties based on the variation of the flow pattern. Applying the critical point theory and coherent structure concept, a flow topology analysis was performed with the help of computational fluid dynamic simulations. The compartments were determined by the fluid flow, and the dynamic behavior of the compartments was taken into account. Under normal diurnal load variation, the architecture of the compartments did not change, in contrast to the mass transport between the zones, whereas the sludge removal process made significant changes in the architecture. The results showed two main flow zones with significant internal recirculation in the first zone. The hydraulic surface loading was examined in each zone, and the study revealed that the actual hydraulic load could be from 1.5 to 4.5 times much higher than that in individual zones due to recirculation eddies in the reactor tanks. The design hydraulic loading rate did not consider the local flow pattern. The discrete phase model approximation provided acceptable results, and the extent of the recirculation zone changed stepwise with different loads.

Wastewater treatment is an energy-intensive process for treating liquid-phase pollutants in urban settlements. The aerobic processes of the biological treatment involve a significant air demand. An optimal control strategy could be used to minimize the amount of excess air entering the system due to safety factors applied in the design procedures. A plant-wide mechanistic modeling approach including an activated sludge model and one-dimensional settler model was proposed as an effective tool for predicting the actual air demand and for selecting the optimal aeration strategy. In this study, a sewage treatment plant receiving strong influent flow was investigated. At the sludge ages of 14–18 days, the plant was capable of achieving a 90% organic matter reduction and 85% nutrient reduction. By applying a constant dissolved oxygen concentration of 1.5 mg/L, the air demand decreased by 25%, which could be further increased by 10% if the cascade ammonium control approach was applied at peak periods. The dependence of the aeration energy demand on the temperature and dissolved oxygen was formulated, meaning the operators could select the optimal setpoint and minimize the energy consumption while the effluent quality requirements were met.

A junction structure of the greatest combined sewers of Budapest (Hungary) was under hydrodynamic and water quality examinations.The selected junction performs an important role in the operation of a combined sewer overflow.The main environmental effects are on the receiving water body, on the biggest main sewer and on the wastewater treatment plant.In the first step, one-dimensional hydrodynamic simulation was executed for the main and lateral inflow sewers.The simulation results were presenting the open surface elevations of the water flow.In the next step, a 3D fluid flow model was built based on a steady state simulated flow assumption.The resulting velocity and turbulence distribution were showing the critical points of the structure and the joining conduits.The simulation without the lateral inflow highlighted the negative effect of the lateral inflow.The high velocity of the inflowing water is forcing the main branch flow to slow down.The water level and the sedimentation are increasing upstream in the main sewer.Historical sediment volumes data and frequent flooding complaints are confirming the simulation results.Suggestions based on 3D model simulations are given for the improvements.

Sequencing batch reactor systems in wastewater treatment is widely applied activated sludge technology. The system performance is not only dependent on the raw sewage quality and biochemical processes, but the flow pattern within the reactor has a significant impact on the treatment itself. The varying stages of the operation require different fluid flow conditions; biological stage shall be appropriately mixed, whereas low velocity zones favor the phase separation. The aim of this study was to improve sequencing batch reactor operation in order to optimize the treatment efficiency. Numerical fluid dynamic simulations were performed to determine the substrate and biomass homogeneity inside the reactor at the biological phase and the rate of the decantation was estimated at the sedimentation phase. The settling model was calibrated by field measurements. The results revealed that the hydraulic efficiency of the reactor was 87% and the achievable settled solid content was 0.9%.

On-site wastewater treatment systems are gaining popularity in areas where centralized wastewater treatment is not available. In the current case study a domestic activated sludge system was investigated, where treated effluent was stored in a short-term (1 week turn-over time) and a long-term (over 2-3 months) storage tank and was then used for irrigation. This design provided a unique opportunity to assess the chemical and microbial changes of the effluent upon storage. Long-term storage greatly improved both the chemical quality and the degradation efficiency of most organic micropollutants examined, including petroleum hydrocarbons and the pesticide diethyltoluamide. Taxonomic profile of the core microbiome of the effluent was also influenced upon storage. Relative abundance values of the members of Azoarcus and Thauera genera, which are important in degrading polycyclic aromatic hydrocarbons compounds, clearly indicated the biodegrading activity of these microbes across samples. The abundance of xenobiotics degradation functions correlated with the observed organic micropollutant degradation values indicating efficient microbial decomposition of these contaminants. Functions related to infectious diseases also had the highest abundance in the short-term storage tank corresponding well with the relative abundance of indicator organisms and implying to the significance of storage time in the elimination of pathogens. Based on these results, small, on-site wastewater treatment systems could benefit from long-term storage of wastewater effluent.

A Computational Fluid Dynamics (ANSYS Fluent CFD) software was applied for the examination of a critical combined sewer section of Budapest (Hungary) sewer network.The critical part of the main branch is located at a combined sewer overflow (CSO) which is implying environmental risk for the receiving water body.The CFD simulations proved the anticipated disadvantageous hydrodynamic effects of the lateral inflow.A discrete phase model (DPM) was also applied to analyse the sediment transport and settling conditions around a junction structure in the main branch.Various parameters set in the model were recommended.The DPM simulations confirmed the anticipated negative effects of the lateral flow to the sedimentation in the main branch.The effects of the possible change of the particle size distribution were also examined.The smaller were the diameters the less was the sedimentation in the critical section of the main branch.Recommendation for the improvements of the main branch regarding the sedimentation processes were stated including local and wider range solutions.

Decentralized wastewater systems treat, dispose and reuse the wastewater in the vicinity of source, reducing the sewage transportation cost to minimal. As an alternative to centralized systems it can function as a satellite system or an individual wastewater treatment unit. Design an onsite facility applies the same sizing procedure compared the conventional large scale systems, whereas the input flow data and its variability, the model parameters could differ. In this study a small size treatment unit was designed by biokinetic modeling, where the model parameters were estimated using analytical methods. As a result of the calculation the biomass build-up and the quality of the treated effluent was predicted and the operation parameters were determined in summer and winter operation.

A különböző szennyvízkibocsátások elvezetése, kezelése kiemelt fontosságú a közegészségügyi kockázatok elkerülése és a befogadó vízminőségének megóvása érdekében. A csatornahálózat kiépítésekor arra törekszünk, hogy a szennyvíz szállítását úgy végezzük, hogy abban biológiai folyamatok, iszaplerakódás ne induljon be. Az urbanizáció hatására a meglévő hálózatok túlterheltté válhatnak, a telepre a szennyvíz hosszabb úton érkezhet meg. A kiszolgált agglomeráció bővülése esetén szóba jöhetnek decentralizált szennyvízkezelő megoldások, melyek lehetnek a szennyvíz keletkezési helyénél létesített több kisebb kapacitású telep, kisebb lakóövezet, egy-két családot kiszolgáló egyedi kisberendezés és/vagy természetközeli (extenzív) szennyvíztisztítási rendszerek. A cikk célja ezen lehetőségek feltárása. A projekt az Európai Unió támogatásával, az Európai Szociális Alap (ESZA) társfinanszírozásával valósul meg (a támogatási szerződés száma: EFOP-3.6.1-16-2016-00025, projekt címe: A vízgazdálkodási felsőoktatás erősítése az intelligens szakosodás keretében).

In Hungary subsurface water courses are used generally (95%), which may contain numerous pollutants (from natural or anthropogenic source). Most of these pollutants can be removed by oxidation followed by phase separation. By applying oxidizers hydrodynamic conditions have a significant role in the process; the chemical added shall be perfectly mixed with the raw water in order to react with the soluble pollutants. For the removal of iron and manganese in subsurface water generally potassium permanganate is applied. In this paper the installation of mixers was optimized and propeller and paddle mixers at various rotational speed. As a result of the research it can be stated that paddle mixer has higher mixing efficiency compared to propeller mixer, since the contact surface area between the mixer and water is also higher.

Denitrification is a key process in wastewater treatment since it is responsible for the effective nutrient removal. It requires anoxic conditions, where only chemically bound nitrogen is used as an oxygen source, and no aeration is applied. In suspended biomass systems the growth and homogenization of biomass is essential, high degree of mixing is required, which is achieved only by using mechanical mixers. Mechanical mixing performance relies on the mixing power determined by the equipment dimensions and rotational speed. In this paper the effect of three different rotational speed (rpm: 100, 400, 900 min-1) on flow field and mixing conditions are evaluated. As a result of the simulations, the acceptable flow field was achieved at 400 rpm. The outcome of this research is that the high degree of energy transfer from mixers to fluid flow deteriorated mixing efficiency.

Attached growth process in wastewater treatment is widely used in order to achieve the sufficient biodegradation of organic matter and nutrient removal. Since the biofilm is attached to a carrier in this process, the substrate and oxygen shall be transported to the biomass surface and reach the deeper layer of the biofilm via diffusion. The driving force of the process is the dissolved oxygen (DO) concentration difference, therefore at least 4–5 mg/L DO is required in this system, which is relatively high compared to activated sludge, where the DO is 1.8–2.5 mg/L. In the attached growth systems, where the suspended matter concentration is low, the relative oxygen diffusion rate (α) is about 0.7–0.8, which is an elevated value compared to the activated sludge system, where alpha is 0.4–0.5. The aim of this paper is to estimate the aeration requirement of the wastewater system applying biofilm; the above mentioned two properties are to be taken into account and the results will be compared to the conventional activated sludge system aeration need.