Bacterial immobilization is a promising approach to address the issues of biomass retention, toxicity sensitivity and operational instability of free-cell system in wastewater treatment. A critical review of using biochar as an engineered carrier for bacterial immobilization is presented, discussing the connections between biochar characteristics, bacterial colonization, the ability to capture and transform pollutants, mass transfer, operation, and long-term stability of the reactors. The evidence suggests biochar can be a porous habitat for microbes which can also act as a reactive sorbent, allowing for coupled adsorption–biodegradation and enhancing microbial tolerance of adverse conditions. The efficiency of pollutant removal ranges up to 99.5
This study presents a novel automated framework for the calibration and validation of rain-on-grid (RoG) hydrodynamic models at the catchment scale, with specific application to the TUFLOW HPC platform. The proposed approach establishes an integrated and automated workflow that links rainfall input directly to flood response, enabling efficient calibration of key hydraulic parameters, including Manning’s roughness, initial loss, and continuous loss. The framework combines ensemble-based parameter sampling, automated model execution, data-driven surrogate modelling, and evolutionary optimization algorithms (EAs) to systematically explore parameter combinations within the defined calibration ranges. Three modelling techniques—Random Forest (RF), Gaussian Process Regression (GPR), and Gradient Boosting (GB)—are employed to approximate model responses from an ensemble of hydrodynamic model simulations, thereby accelerating the calibration process and reducing computational costs. Furthermore, three EAs, consisting of Particle Swarm Optimization (PSO), Invasive Weed Optimization (IWO), and Differential Evolution (DE), are applied. The optimization objective is defined as minimizing the discrepancy between simulated and reference inundation extents, quantified through total inundated area derived from benchmark inundation datasets. The entire process is implemented in a MATLAB-based script that automatically controls TUFLOW simulations, iteratively adjusts parameters, and evaluates model performance without manual intervention. The framework is tested in a small catchment case study under multiple design rainfall events (50-, 100-, and 500-year return periods). Results demonstrate close agreement between the simulated and reference inundation areas, with differences of less than 1
Submarine sewage outfalls are widely used to mitigate the impacts of wastewater discharges on coastal recreational waters. However, an outfall’s environmental performance depends not only on its location but also on the complex interaction among local hydrodynamics, near-field dilution, far-field transport, and bacterial decay processes. This study presents an integrated numerical modelling framework to evaluate alternative locations for a submarine sewage outfall on a tropical coast in southeastern Brazil. The methodology couples hydrodynamic circulation, near-field plume dynamics, far-field transport, and water-quality simulations within the SisBaHiA® modelling system. Model performance was assessed by comparing it with field observations of current velocities, increasing confidence in the representation of the local hydrodynamic regime. The validated framework was subsequently applied to compare four alternative outfall alignments under representative environmental conditions. Results demonstrated substantial differences in plume dispersion, dilution, bacterial decay, and the frequency of bathing-water standard exceedances among the alternatives, highlighting the dominant influence of coastal circulation patterns on wastewater transport. Among the evaluated scenarios, the offshore alignment achieved the greatest dilution and the lowest predicted impacts on recreational water quality. Beyond identifying the most suitable outfall configuration for the study area, the proposed modelling framework provides a transferable methodology to support the environmental design and optimisation of submarine outfalls in coastal regions subject to complex hydrodynamic conditions. Four outfall alignments showed distinct impacts on nearby bathing waters. Coastal contamination risk was not determined solely by offshore distance. One alignment consistently reduced the risk of E. coli exposure.
In this paper, we propose a method to estimate missing extreme values in streamflow time series. In practice, the problem arises mainly for peak discharges, in cases that measuring devices fail. Our method is based on the use of 3rd -degree Hermite polynomials. Their four coefficients can be calculated based on four known flowrate values, namely the two preceding and the two succeeding the missing peak. In this way, the available adjacent flowrate values and the slopes of both the ascending and the descending branches of the streamflow curve are retained. Moreover, an approximate error bound can be calculated. The proposed methodology is tested using recorded data from seven measuring stations on five rivers of different magnitudes and of quite different geographic and climatic zones, namely two rivers in India and three in Greece. In these application examples, the estimated maximum streamflow values (measured in m3/s) vary from few dozens to dozens of thousands, while measuring frequencies range from hourly to daily. Results of more applications are briefly presented and compared with those from linear and quadratic interpolation. Comparison is based on the relative error between the actual and the computed peak value. The Hermite interpolation methodology generally outperforms them. It can be concluded that the method, which is described in this paper, can be efficiently used to estimate missing extreme river flowrate values between ascending and descending smooth hydrograph branches, using two preceding and two succeeding flowrate values. Moreover, a theoretical upper error bound can be calculated. We propose 3rd-degree Hermite polynomials to estimate missing peak streamflow values. The methodology is tested using field data from gauging stations in Greece and India. The errors (differences between actual and estimated flowrate values) are calculated. A procedure to calculate an approximate error bound is illustrated. The results are compared to those of linear and quadratic interpolation methods.
Agricultural water reuse involving the blending of treated wastewater (TWW) with conventional irrigation water in open irrigation networks is not explicitly regulated under Regulation (EU) 2020/741, which may present exposure pathways comparable to unblended direct reuse. This study assessed water quality dynamics along a fully operational irrigation canal network in Northern Italy, under real-scale hydraulic and agronomic conditions characteristic of reuse systems involving blending, in which TWW discharged from a wastewater treatment plant (WWTP) accounted for 68
