Water Technology (Australia)

Agricultural production remains highly susceptible to water-related risks, such as drought and flooding. Although hydrologic forecasting systems, such as the National Water Model (NWM), have advanced considerably, their outputs are rarely used for real-time agricultural decision-making. This study developed the Agricultural Water Risk Indicator (AWRI), a framework that translates NWM streamflow forecasts into crop-specific risk assessment indicators. The AWRI framework has three key components: (1) the hydrological threat and exposure characterization based on NWM streamflow forecasts (B1); (2) crop sensitivity by growth stage and water needs (B2); and (3) adaptive capacity reflecting the presence of irrigation or drainage infrastructure (B3). The AWRI was evaluated across three NWM reach IDs covering five farm sites in the Black Belt region of Alabama, USA. The results show that the AWRI captured variations in hydrologic conditions, risk, and crop tolerance across the research sites within the one- to four-week forecast range. Crops in the reproductive stage were especially sensitive. Without resilience measures, up to 55% of the crops simulated at some sites had high-risk AWRI categories. Including irrigation or drainage decreased risk scores by one to two levels. The AWRI tool provides farmers and stakeholders with critical information to support proactive agricultural water management.

Monitored natural attenuation is commonly used to manage petroleum hydrocarbon-contaminated groundwater. However, it requires periodic, costly grab sampling. We propose a cost-effective, real-time groundwater monitoring proof-of-concept machine learning (ML) framework using in-situ sensors-pH, dissolved oxygen, electrical conductivity, and redox potential-to detect benzene, ethylbenzene, and xylenes (BEX). We built upon the established correlations between hydrocarbon concentrations and in-situ water quality parameters (iWQPs). Due to limited field data, we validated the framework using datasets at virtual wells within a simulated aquifer from our previously developed reactive transport model. In this application, we detected the spreading of pollution downstream of the established pollution plume. The used framework is a binary classification system that flags contamination at virtual downstream wells. We compared five ML classifiers, i.e. Logistic Regression, Random Forest, XGBoost, Multi-layer Perceptron, and Support Vector Classifier, for early warning when BEX reached or exceeded the regulatory threshold of 5μg/L. The models were trained on virtual wells at and near the source zone and predicted contamination before BEX reached the threshold at downstream virtual wells. This reflects the spatial variability in flow and reaction dynamics that altered BEX-iWQP relationships. Scenario analyses revealed the ML models' sensitivity to aquifer properties, i.e., hydraulic conductivity, electrical conductivity, and electron acceptor availability. We also assessed the impact of sensor noise and seasonal fluctuations on iWQPs. We found that even moderate levels of noise (10-20%) can significantly affect model accuracy, particularly when the noise was introduced into the test data. Therefore, we recommended to combine hardware stabilization with adaptive smoothing techniques. With these approaches, our proposed framework remains promising for providing early warnings of plume migration toward sensitive receptors.

Aerobic granular sludge (AGS) is a promising technology for wastewater treatment due to its excellent settling and pollutant removal capabilities. However, its long granulation period and instability under real wastewater conditions hinder full-scale application. This study evaluated calcium addition at the influent (R1) and aeration stage (R2) under real wastewater, focusing on granulation, oxygen transfer, EPS production, microbial activity, and economic benefits. Aeration-phase dosing (R2) significantly improved granule formation (>200 μm, 33.73% vs 13.41%), compactness, and inorganic content. It enhanced LB-EPS and TB-EPS secretion, calcium retention (2.51% vs 0.91%), and hydroxyapatite (HAP) formation, resulting in stronger granules (SVI30/SVI5 > 0.9). R2 showed higher oxygen transfer efficiency (KLa = 1.21 vs 0.81 s–1), promoted heterotrophic activity (RH/T = 65.10% vs 62%), upregulated AOB genes (amoA, amoB, amoC), and suppressed NOB genes (nxrA). Increased nirK and norB expression indicated partial nitrification-denitrification. Economically, R2 reduced calcium use by 63.6% and shortened granulation by ∼30 days. These findings demonstrate that aeration-phase calcium addition enhances EPS–mineral synergy, microbial performance, and structural stability, offering a cost-effective and scalable strategy for AGS applications.

The ultrasonic signal amplitudes obtained from non-collinear wave mixing has previously shown significant changes for physically aged Poly-Vinyl Chloride (PVC) pipes, demonstrating the method's effectiveness in assessing the ageing condition of PVC. However, the exact relationship between the measured amplitudes and the extent of physical ageing in PVC has yet to be established. Additionally, it has not yet been validated against established methods or applied to determine the service lifetime of PVC pipes. This study outlines a three-step process to validate the effectiveness of the non-collinear wave mixing technique for assessing the physical ageing of PVC pipelines. Firstly, the non-collinear wave mixing results are compared with the established laboratory method of differential scanning calorimetry, to validate the scattered wave amplitude measurements. Secondly, employing the Arrhenius relation, service lifetime estimates derived from non-collinear wave mixing results align within the expected magnitudes, emphasizing the technique's potential for in-situ pipeline inspections. Finally, a material model is utilized to estimate the Third Order Elastic Coefficient (TOEC) m based on the measured amplitudes, demonstrating a linear correlation with annealing time. A 50% change in TOEC m signifies a brittle state, indicating a high risk of failure. A combination of experimental and analytical analyses highlighted TOEC m variations as the primary factor influencing non-collinear wave mixing amplitude changes during physical ageing. This comprehensive approach also highlights the importance of incorporating diverse factors to precisely forecast and oversee the performance of PVC pipes in real-world environments.

Energy-efficient capture technologies need to be deployed by 2050 to abate global warming caused by excessive carbon dioxide (CO2) emissions. CO2 capture using alkaline solutions and absorbent regeneration mediated through bipolar membrane electrodialysis (BMED) have been tested previously as a standalone technology. However, the continuous operation of an integrated system remains largely unclear. Here, a bench-scale study was conducted using an integrated prototype to analyze the performance of CO2 capture and electrochemical regeneration using potassium hydroxide (KOH) aqueous solution. A wide range of current densities from 150 to 1000 A/m2 was applied to demonstrate the continuous operation of the CO2 capture system emphasizing the stability in attainable high rich carbon loading and CO2 desorption. The electrochemical regeneration module achieved CO2 desorption efficiency of 70% and absorbent recovery up to 89% under industrial relevant current densities of 500–1000 A/m2. The absorbent recovery has been identified to be a result of the combined effect of load ratio and rich carbon loading. The observed inefficient CO2 separation indicates significant potential to enhance energy efficiency. These results represent a pivotal step forward in electrochemically mediated CO2 capture technology, with promising potential for rapid industrial scale-up in the near future.

As part of the Mini-Adaptive Sampling Test Run (MASTR) experiment in the Gulf of Mexico (GoM) region from February to April 2024, we demonstrated real-time deterministic and probabilistic reachability analysis and time-optimal path planning to guide a fleet of four ocean gliders. The governing differential equations for reachability analysis and time-optimal path planning were numerically integrated in real-time and forced by currents from our large-ensemble ocean forecasts. We illustrate the real-time deterministic and probabilistic forward reachability analyses, reachability and path planning for glider pickups, time-optimal path planning for gliders in distress, and planning of future glider deployments. Results show that the actual paths of gliders were contained within our reachable set forecasts and in accord with the dynamic reachability fronts. Our time-optimal headings and paths also predicted real glider motions, even for longer-range predictions of weeks to a month duration. Reachability and time-optimal path planning forecasts were successfully employed for glider recovery. They also enabled exploring options for future glider deployments.

Experimental investigations into the characterization of vortices in hyperbolic funnels have shown efficient aeration properties. Certain regimes of vortices have been observed to exhibit high gas dissolution rates. This phenomenon has prompted inquiries into the underlying physical mechanisms at both micro and macroscopic scales. The present study employs computational fluid dynamics to numerically analyze the flow field organization inside these vortices, aiming to elucidate the observed high gas transfer rates. Transient simulations are performed on a three-dimensional radially structured hexahedral mesh, utilizing a multiphase Euler–Euler approach-based volume of fluid method for modeling, along with shear stress transport turbulence modeling based on k−ω equations with curvature correction. The evaluation of the two vortex regimes was conducted in terms of hydraulic retention time, water volume in the reactor, air–water interfacial area, and bulk mixing. Instabilities resembling Taylor vortices observed in Taylor–Couette flow systems emerge in the secondary flow field of these vortical structures, facilitating turbulent mixing. A qualitative analysis of the strength of these instabilities in terms of average vorticity per unit mass of water explains the high gas transfer efficiency. Despite high gas transfer rates, water exiting the funnel remains undersaturated under given operating conditions due to the short hydraulic retention time.