Hydraulic Loading Research Articles

Comparative analysis of conventional and modified constructed wetlands for the removal of trace organic compounds from municipal wastewater effluent.

Comparative analysis of conventional and modified constructed wetlands for the removal of trace organic compounds from municipal wastewater effluent.

Innovative Bio retention Strategies: Enhancing Dissolved Nitrogen Removal with Biochar-Amended High-Permeability Media for Urban Storm water Treatment

Nutrient pollution from stormwater leads inland and coastal water bodies to become eutrophic, which results in sea grass receding and harmful algal blooms (HAB) flourishing. These human-induced effects destabilize the ecosystems, and some HABs threaten human health directly. A possible solution to this problem is bioretention, defined as the storage and controlled discharge of storm water runoff in an ecologically constructed setting. But since it is largely reliant on particle settling as a nutrient removal process, it struggles with pollutants such as dissolved nitrogen. This is particularly inconvenient in India, where nitrogen is the limiting nutrient for HAB growth owing to the geological significance of phosphorus. Several conventional bio retention systems are limited by their low hydraulic loading rates (HLRs) and extensive footprint requirements, rendering them impractical for densely urbanized areas. To address these constraints, we performed a series of bench-scale, column, and pilot-scale experiments using a novel mixed media of high-permeability gravel amended with biochar. These tests were designed to characterize the hydraulic and physical properties of the amended media, assess its runoff treatment performance under a high HLR representative of extreme precipitation events, and quantify its mass removal efficiency for dissolved nitrogen species at a low HLR corresponding to median storm conditions. Collectively, these investigations aim to identify a more space-efficient solution capable of handling both extreme and typical storm water loads. To determine the air-to-water ratio in the soil and assess whether aerobic nitrification or anaerobic denitrification is promoted, HPG was amended with biochar at different volumetric ratios and tested for porosity and moisture retention at the bench scale. Porosity and moisture‐retention capacity increased in direct proportion to the percentage of biochar in the media. Saturated hydraulic conductivity was determined through column tests, and found to be slightly reduced.

From Prediction to Remediation: Characterization of Tropical Landfill Leachates Using ARIMA and Application of Adsorption and Reverse Osmosis Treatments

Landfill leachates in tropical regions represent a critical environmental challenge due to their complex composition and pronounced seasonal variability. This study sought to characterize leachates from a tropical landfill in Valledupar, Colombia, and to evaluate advanced treatment technologies for the removal of organic pollutants. An ARIMA (3,0,3) model was implemented on an eight-year time series (2016–2023) of leachate flow data to identify seasonal patterns and support hydraulic load forecasting. Physicochemical characterization was conducted following APHA standard methods, which revealed high levels of COD, BOD5, chlorides, and lead. Two treatment technologies were assessed independently: (i) adsorption using granular activated carbon in batch and continuous-flow systems, under 36 experimental conditions that combined pH levels (2–7) and carbon dosages (20–120 g); and (ii) reverse osmosis employing polyamide membranes operated at 18 bar and at pH values of 6.0, 7.0, and natural (unaltered) conditions. The results confirmed that leachate generation exhibits clear seasonal variability correlated with rainfall patterns. The Langmuir isotherm demonstrated the best fit at pH 4.0 (R2 = 0.9685), and the continuous system achieved 97% COD removal within 90 min. Reverse osmosis consistently removed over 94% of COD and BOD5 across all pH conditions. These findings highlight the value of integrating time-series forecasting with optimized treatment technologies to support effective and adaptive leachate management strategies in tropical environments.

Dimensionless analytical model for non-ideal breakthrough in fixed beds: Application to trivalent amphoteric oxide sorbent materials.

Dimensionless analytical model for non-ideal breakthrough in fixed beds: Application to trivalent amphoteric oxide sorbent materials.

Hydraulic efficiency and mixing dynamics in surface flow constructed wetlands: Influence of design, vegetation phenology, and climate variability.

Hydraulic efficiency and mixing dynamics in surface flow constructed wetlands: Influence of design, vegetation phenology, and climate variability.

Research on steady state hydrodynamics and structural improvement of micro valves

In micro-scale high-speed switching ball valve systems, the synergistic effects of substantial flow rates and elevated response frequencies amplify the hydraulic loading on the valve spool, consequently impeding its kinematic performance. This establishes hydraulic force analysis and compensation as pivotal elements in optimizing the operational characteristics of high-frequency ball valves. Confronting the inadequacy of conventional steady-state hydraulic force formulations under high-frequency switching conditions characterized by complex flow field configurations, this investigation employs Computational Fluid Dynamics (CFD) methodology for comprehensive hydraulic force characterization. The research protocol encompasses three principal phases: Initially, a parameterized fluid domain model of the valvular flow field is constructed utilizing ANSYS Workbench platform. Subsequently, flow simulations are conducted through implementation of the standard k-ε turbulence model, enabling quantitative extraction of pressure distributions, streamline topologies, flow rate profiles, and steady-state hydraulic force characteristics across discrete valve opening positions. Ultimately, systematic structural optimization is performed through parametric analysis correlating orifice geometry with spool force dynamics, thereby determining optimal configuration parameters to mitigate hydraulic force attenuation during transitional states. Key findings demonstrate a non-monotonic relationship between inlet-side steady-state hydraulic force and valve opening displacement, exhibiting initial augmentation followed by gradual diminution. The redesigned seat geometry successfully achieves 22.6% reduction in steady-state hydraulic force (0.05 mm opening condition) relative to baseline configuration, confirming effective compensation for transitional force attenuation. This optimization strategy provides critical insights for enhancing the dynamic response and operational stability of micro-scale high-speed fluid control systems.

Evaluating the purification efficiency of Moroccan waste stabilization ponds’ systems

Lagoon wastewater treatment systems, introduced in 1970, have become a preferred economic solution in Morocco due to favourable climatic and economic conditions. However, these facilities often face performance problems, particularly related to excessive hydraulic and pollutant loads, resulting in treatment efficiencies below regulatory standards for urban discharges. Waste stabilization ponds in Morocco show average reduction rates of 70 % for chemical oxygen demand, 65 % for biochemical oxygen demand during 5 days, and 62 % for suspended solids. This study aims to evaluate the performance of seven lagoon treatment plants in different regions of the country and identify solutions to ensure compliance with discharge standards. The Moroccan experience in biological lagoon treatment is valuable for improving purification efficiency, with observed reductions of chemical oxygen demand, biochemical oxygen demand during 5 days, and suspended solids of 65 %, 54 %, and 62 % respectively, proposing strategies to optimize these processes and ensure adherence to specific norms.

Comparative Assessment of Wastewater Treatment Technologies for Pollutant Removal in High-Altitude Andean Sites

This study evaluated the pollutant removal efficiency of two decentralized wastewater treatment plants (WWTPs) located in the high-altitude southern Andes of Ecuador, Acchayacu and Churuguzo, from 2015 to 2024. Acchayacu previously operated using an upflow anaerobic filter (UAF), and from 2021, it transitioned to using vertical-subsurface-flow constructed wetlands (VSSF-CWs). In contrast, Churuguzo employs surface-flow constructed wetlands (SF-CWs). These systems were assessed based on parameters such as the five-day biochemical oxygen demand (BOD5), chemical oxygen demand (COD), total phosphorus, organic nitrogen, ammonia nitrogen, total solids, fecal coliforms (TTCs), and total coliforms (TCs). The data were divided into two subperiods to account for the change in technology in Acchayacu. Statistical analysis was conducted to determine whether significant differences existed between the treatment efficiencies of these technologies, and the SF-CW was found to consistently outperform both the UAF and VSSF-CW in removing organic matter and microbial pollutants. This difference is likely attributed to the longer hydraulic retention time, lower hydraulic loading rate, and vegetation type. The findings highlight the environmental implications of treatment technology selection in WWTPs, particularly regarding the quality of receiving water bodies and their potential applications for public health, proper water resource management, and the design of decentralized systems in high-altitude regions, especially in developing countries.

French Type Vertical Flow Constructed Wetland as a Sustainable Solution for Domestic Sewage Treatment.

In order to mitigate the risk posed by discharge of untreated wastewater and enhance the quality of wastewater prior to its release or reuse, it is important to adopt nature based treatment technologies. The current study was performed with objective to treat the primary treated sewage collected from a traditional Moving Bed Biofilm Reactor (MBBR) based Sewage treatment plant (STP) by using a two-stage French Type Vertical Flow Constructed Wetland (FVFCW). This pilot-scale study was undertaken in Banaras Hindu University Campus Varanasi, Uttar Pradesh. The wetland unit was a two-stage Vertical Flow Constructed Wetland system (VFCW) filled with two different filter media gravel & sand and planted with two different macrophytes Canna indica and Typha latifolia which was operated for Sustainable treatment of primary sewage. The VFCW was operated at three different Hydraulic loading rate (HLR) i.e. 1800, 2700, 3600 L/day for nine months. The VFCW performed for the treatment of different physicochemical parameters at given loading rates. The maximum removal efficiency of 72.37, 76.47, 100, 87.23, 41.41, 40.77 27.07% was recorded for COD, BOD, Turbidity, TSS, TDS, Phosphate and Ammonia respectively. Most of the Parameters showed maximum removal efficiency at HLR 2700 L/day. The study suggested that Experimental VFCW can be a sustainable solution for wastewater treatment in remote and rural areas of India as well small colonies due to its eco-friendly, cost-effective, low maintenance cost and lack of operational expertise.

Phosphorus Retention in Treatment Wetlands? A Field Experiment Approach: Part 2, Water Quality

In this study, we hypothesized and tested that physical parameters (flow, transport, and water depth) have a significantly greater influence on phosphorus (P) retention in wetlands than biogeochemical factors. Specifically, we evaluated the null hypothesis (H0), that no significant difference exists between the influence of physical and biogeochemical parameters on phosphorus retention, against the alternative hypothesis (H1), that physical parameters are more influential. We investigated two large wetlands (stormwater treatment areas, STAs) in south Florida: STA34C2A, which is dominated by emergent aquatic vegetation (EAV), and STA2C3, which is dominated by submerged aquatic vegetation (SAV). Building on Part 1, which mapped spatial flow resistance (K) as a vegetation-type-independent proxy for hydraulic resistance, this study (Part 2) applied a novel high-frequency (hourly) data approach with time-lagged regression modeling to estimate total phosphorus (TP) outflow concentrations. The key variables included inflow TP concentration, vegetation volume, water depth, nominal hydraulic residence time (HRT), hydraulic loading rate (HLR), phosphorus loading rate (PLR), and time lag (“P-spiral”). Multi-linear regression models for each STA identified inflow TP and water depth, a controllable physical parameter, as the most significant predictors of TP outflow, while the hour of day (a temporal proxy) contributed the least. Optimal model performance occurred with lag times of 8 and 9 days, producing R2 values of 0.5788 (STA34C2A) and 0.5354 (STA2C3). In STA34C2A, high TP retention was linked to shallow water depth, dense EAV, and low K values, indicating high hydraulic resistance and reduced short circuiting. In contrast, lower TP retention in STA2C3 was associated with longer flow paths, sparse SAV, and high K values, suggesting less hydraulic control despite similar nominal HRTs. These results provide empirical support for rejecting the null hypothesis (H0) in favor of the alternative (H1): physical parameters, especially water depth, hydraulic resistance, and inflow dynamics, consistently exert a stronger influence on P removal than biogeochemical factors such as PLR. The findings highlight the importance of optimizing flow and depth controls in wetland design and management to enhance phosphorus removal efficiency in large, constructed wetland systems.

Enhancement of microorganisms by MgAl-LDO@zeolite composites to buffer the impact of hydraulic loading and maintain physiological activity

Enhancement of microorganisms by MgAl-LDO@zeolite composites to buffer the impact of hydraulic loading and maintain physiological activity

Soil hydro-mechanical behaviors subjected to large and cyclic hydraulic loadings under anisotropic stresses

Soil hydro-mechanical behaviors subjected to large and cyclic hydraulic loadings under anisotropic stresses

Understanding the risk of enhanced particle penetration into slow sand filter beds when using underwater skimming techniques.

This study evaluated abiotic slow sand filters (SSFs) to understand the risk of particle penetration during underwater skimming (UWS), focusing on clogging, headloss development, and particle breakthrough. Pilot-scale filters containing clean sand were challenged with dispersed kaolin particles to simulate surface accumulation, and the sand surface was agitated to mimic UWS procedures. The study was undertaken with no maturation period to consider the worst-case scenario corresponding to the period just after filter skimming. Agitating the surface and restarting flow released captured particles, some moving downward through the filter. Shallow filter depths resulted in particles appearing in the filtrate, but increasing the media depth beyond 500mm minimized this effect. Since 90% of headloss occurred in the upper layers, deeper particle penetration was insignificant. Increasing the hydraulic loading rate from 0.3 to 0.5m/h reduced particle retention by 0.72 log, yet all abiotic SSFs achieved over 2 log particle capture. Small particles (2-10μm) were removed by 2 logs, indicating sufficient non-viral pathogen retention under routine conditions. Effective capture of particles sized 2-125μm suggested minimal risk to water quality and public health during UWS on full-scale SSFs. Using clean sand and kaolin represented a worst-case scenario, excluding biological maturation and particles. The findings suggest that under normal conditions, UWS does not increase deep particle penetration or breakthrough, supporting its safe implementation to enhance filter maintenance without compromising water quality.

MODELLING THE CATASTROPHIC MAY 2023 FLOODS ALONG THE EMILIA ROMAGNA LITTORAL WITH THE COASTS GIS-BASED TOOL

Planning eco-compatible, cost-efficient management strategies ensuring the continuity-of-daily-life and promoting adaptation to climate change can be efficiently supported by GIS-based tools, that allow risk assessment for a number of scenarios and for a variety of clusters of solutions. In this paper the recent flood events along the Emilia Romagna littoral are modeled with the COASTS GIS-based decision support system including different hydraulic models, specifically X-Beach and Mike21. The flooding model results are compared with the available inundation limits recorded after the flood. The hydraulic load considered the combination of rainfall, storm surge, waves and river discharges in the specific area of Cesenatico, a seaside town close to Cesena in northern part of Italy. The inundation modelling restitutes cautious inundation area and therefore the economic damage is also overestimated with respect to the registered damage compensation.

A COUPLED FDM-MPM METHOD FOR MODELING MULTIPLE PHENOMENA OF FLUID AND AND SOIL

This study proposes an advanced analytical framework for investigating soil behavior under hydraulic loading by establishing a coupled soil–water analysis that discretizes fluid flow using the Finite Difference Method (FDM) and soil deformation using the Material Point Method (MPM). Numerical methods for coupled soil–water analysis can generally be classified into grid-based approaches (e.g., the Finite Element Method, FEM) and particle-based approaches (e.g., the Distinct Element Method, DEM). Grid-based approaches often encounter difficulties in dealing with large deformations and collapse phenomena, whereas particle-based approaches can be computationally expensive and may struggle to accurately capture seepage. To overcome these limitations, a coupled fluid–soil analysis model has been developed using MPM, an intermediate method that combines strengths from both grid- and particle-based techniques. The model has been applied to a two-dimensional consolidation and seepage problem. The results indicate that the proposed method can accurately reproduce large deformations and seepage—phenomena that pose challenges for traditional grid-based methods—while also aligning well with earlier findings from particle-based analyses.

NEGATIVELY BUOYANT DEBRIS IMPACT UNDER TSUNAMIS-LIKE CONDITIONS

Field surveys following major coastal disasters, such as the Chile tsunami in 2010 or the Tohoku tsunami in Japan in 2011, have pointed out the lack of resilience of coastal communities to such events and the need to better understand the risks associated with them (Takahashi et al. [2010]; Palermo et al. [2013]; Esteban et al. [2015]). While the primary cause of destruction during tsunamis remains associated with the hydraulic loads (hydrostatic, hydrodynamics, wave impact, etc.), it has been demonstrated that debris loading is also a major cause of damage on structures, mainly through debris impact and damming (Yeh et al. [2014]). In the past decade, multiple studies have addressed debris transport and loading in extreme events (Shafiei et al. [2016]; Ikeno et al. [2016]; Stolle et al. [2018]). However, those studies mainly focused on positively buoyant debris, like wood logs or empty containers, leaving a gap in knowledge. Indeed, Stolle et al. [2020], in a field survey following the Indonesian tsunami in 2018, identified the study of neutrally and negatively buoyant debris as one of five major needs in debris loading research, with even ASCE7-16 Chapter 6 containing limited recommendation on the load associated with those type of debris.

PASSING VESSEL AND TIDAL FLOW IMPACTS ON SUBMERGED TUNNEL ELEMENTS DURING INSTALLATION

A number of numerical and physical model studies were used to assist in the design and future construction of the Oosterweel tunnel Project at Antwerp, Belgium. The tunnel will consist of 8 tunnel elements, to be immersed in water depths of up to 30m with ebb and flood tidal currents up to 2m/s. The design of the immersion and mooring systems are therefore a crucial part of the installation as well as understanding the effects of passing vessel on it, whilst in a temporary state before final back fill. The studies investigate the different hydraulic load cases on various tunnel elements (TEs) during and post immersion. The TEs will be placed starting from the Southern bank of the River Scheldt (Linkeroever) with elements suspended from catamaran pontoons during installation process.

RECESSION BY RANDOM WAVES: INSIGHTS FROM PHYSICAL MODELING OF CONSOLIDATED SANDY BLUFF

Coastal bluffs are dynamic landforms that recede due to various physical processes (Kamphuis, 1990). Understanding these processes is essential for effective bluff erosion management. This research investigates the physical mechanisms governing sandy bluff recession under random waves and fluctuating water levels. Wave action generates hydraulic pressures on the bluff, removing sediment and undermining stability. Toe erosion from wave impact causes undercutting and basal failures. Higher water levels increase hydraulic loading and erosion, while lower levels expose the bluff to more wave action (Buckler and Winters, 1983; Carter et al., 1987). Soil properties significantly affect the erosion response (Arabi and Farhadzadeh, 2019; Arabi and Farhadzadeh, 2022; Farhadzadeh et al., 2022). This paper presents an experimental study of a compacted sandy beach-bluff under random wave actions. The evolution of the bluff profile was monitored along with flow, porewater pressure, and moisture content. The findings provide insight into the complex interactions governing bluff recession.

Pilot Study on Nucleation-Induced Pelleting Coagulation in Treatment of High-Algae Surface Water: Coagulant Dosage and Hydraulic Loading Optimization

This study proposes a circulating pelletized fluidized bed (CPFB) with micro-sand loading for treating high-algae surface water. Key operational parameters (coagulant dosage, flow rate) were optimized to simultaneously remove algae, turbidity, and disinfection byproduct precursors. Results revealed that 20 mg/L polyaluminum chloride (PACl) and 0.8 mg/L PAM achieved optimal removal of algae (density removal > 80%) and organic matter. The fluidized bed exhibited robust performance across algal species, with the highest dichloroacetonitrile (DCAN) precursor removal of 66.20%, demonstrating superior efficiency for trihalomethane precursors over haloacetic acids. These findings provide critical operational guidance for high-algae water treatment using fluidized beds.

COMPREHENSIVE ASSESSMENT OF ENERGY EFFICIENCY OF PUMPING EQUIPMENT WITH ADJUSTABLE DRIVE

The article presents a methodology for comprehensive assessment of the energy efficiency of pumping equipment equipped with variable-speed drives. The influence of frequency control on the energy consumption of pumping systems under various operating conditions is analyzed. An algorithm for calculating specific energy consumption is proposed, taking into account the technical characteristics of the drive, hydraulic load, and consumption profile. Practical application examples of the methodology are provided based on experimental and simulation data. The results obtained confirm the feasibility of implementing variable-speed drives as an effective means of improving the energy efficiency of pumping systems. The proposed methodology can be used for the techno-economic justification of modernization or the design of new facilities for water supply, wastewater treatment, and other technological systems based on pumping equipment. The use of a regulated electric drive, in particular a frequency converter, allows you to optimize the operation of pumps in accordance with changes in load, which helps reduce energy consumption. However, for an objective assessment of efficiency, a comprehensive approach is required, which takes into account not only changes in electricity consumption, but also hydraulic efficiency, operating characteristics, technical condition of the equipment and the economic feasibility of investing in modernization.