Water science and engineering最新文献

It is necessary to treat pathogen-infected water before its utilisation. Of conventionally used treatment methods, solar photocatalysis has gained considerable momentum owing to its operational simplicity and capacity to use freely and abundantly available solar energy. This article systematically reviewed the disinfection of water with photocatalysis. It addressed the concerns of microbial infection of water and the fundamentals behind its treatment with photocatalysis. It presented an in-depth description of pathogenic deactivation with powerful reactive oxygen species. Special emphasis was given to process intensification as it is an attractive technique that provides multifunctionality and/or equipment miniaturisation. Solar reactor design regarding mobilised/immobilised photocatalysts and compound parabolic concentrators were elucidated. Finally, key parameters governing photoperformance, corresponding trade-offs, and the need for their optimisation were discussed. Overall, this article is a single point of reference for researchers, environmentalists, and industrialists who address the ever-severing challenge of providing clean water whilst also maintaining energy sustainability.

The extreme rainfall event of July 17 to 22, 2021 in Henan Province, China, led to severe urban waterlogging and flood disasters. This study investigated the performance of high-resolution weather forecasts in predicting this extreme event and the feasibility of weather forecast-based hydrological forecasts. To achieve this goal, high-resolution precipitation forecasts from the Tianji weather system and the forecast system of the European Centre for Medium-Range Weather Forecasts (ECMWF) were evaluated with the spatial verification metrics of structure, amplitude, and location. The results showed that Tianji weather forecasts accurately predicted the amplitude of 12-h accumulated precipitation with a lead time of 12 h. The location and structure of the rainfall areas in Tianji forecasts were closer to the observations than ECMWF forecasts. Tianji hourly precipitation forecasts were also more accurate than ECMWF hourly forecasts, especially at lead times shorter than 8 h. The precipitation forecasts were used as the inputs to a hydrological model to evaluate their hydrological applications. The results showed that the runoff forecasts driven by Tianji weather forecasts could effectively predict the extreme flood event. The runoff forecasts driven by Tianji forecasts were more accurate than those driven by ECMWF forecasts in terms of amplitude and location. This study demonstrates that high-resolution weather forecasts and corresponding hydrological forecasts can provide valuable information in advance for disaster warnings and leave time for people to act on the event. The results encourage further hydrological applications of high-resolution weather forecasts, such as Tianji weather forecasts, in the future.

With the development circular economy, the use of agricultural waste to prepare biomass materials to remove pollutants has become a research hotspot. In this study, sunflower straw activated carbon (SSAC) was prepared by the one-step activation method, with sunflower straw (SS) used as the raw material and H₃PO₄ used as the activator. Four types of SSAC were prepared with impregnation ratios (weight of SS to weight of H₃PO₄) of 1:1, 1:2, 1:3, and 1:5, corresponding to SSAC1, SSAC2, SSAC3, and SSAC4, respectively. The adsorption process of acid fuchsin (AF) in water using the four types of SSAC was studied. The results showed that the impregnation ratio significantly affected the structure of the materials. The increase in the impregnation ratio increased the specific surface area and pore volume of SSAC and improved the adsorption capacity of AF. However, an impregnation ratio that was too large led to a decrease in specific surface area. SSAC3, with an impregnation ratio of 1:3, had the largest specific surface area (1 794.01 m²/g), and SSAC4, with an impregnation ratio of 1:5, exhibited the smallest microporosity (0.052 7 cm³/g) and the largest pore volume (2.549 cm³/g). The adsorption kinetics of AF using the four types of SSAC agreed with the quasi-second-order adsorption kinetic model. The Langmuir isotherm model was suitable to describe SSAC3 and SSAC4, and the Freundlich isotherm model was appropriate to describe SSAC1 and SSAC2. The result of thermodynamics showed that the adsorption process was spontaneous and endothermic. At 303 K, SSAC4 showed a removal rate of 97.73% for 200-mg/L AF with a maximum adsorption capacity of 2 763.36 mg/g, the highest among the four types of SSAC. This study showed that SAAC prepared by the H₃PO₄-based one-step activation method is a green and efficient carbon material and has significant application potential for the treatment of dye-containing wastewater.

Significant changes in water cycle elements/processes have created serious challenges to regional sustainability and high-quality development in the Yellow River Basin in China. It is necessary to investigate the impacts of climate change and human activities on hydrological evolution and disaster risk from a holistic perspective of the basin. This study developed initiatives to clarify the mechanisms of hydrological evolution in the human-influenced Yellow River Basin. The proposed research method includes: (1) a tool to simulate multiple factors and a multi-scale water cycle using a grid-based spatiotemporal coupling approach, and (2) a new algorithm to separate the responses of the water cycle to climate change and human impacts, and de-couple the eco-environmental effects using artificial intelligence techniques. With this research framework, key breakthroughs are expected to be made in the understanding of the impacts of land cover change on the water cycle and blue/green water re-direction. The outcomes of this research project are expected to provide theoretical support for ecological protection and water governance in the basin.

Identifying the factors affecting drinking water consumption is essential to the rational management of water resources and effective environment protection. In this study, the effects of the factors on rural drinking water demand were studied using the adaptive neuro-fuzzy inference system (ANFIS) and hybrid models, such as the ANFIS–genetic algorithm (GA), ANFIS–particle swarm optimization (PSO), and support vector machine (SVM)–simulated annealing (SA). The rural areas of Hamadan Province in Iran were selected for the case study. Five drinking water consumption factors were selected for the assessment according to the literature, data availability, and the characteristics of the study area (such as precipitation, relative humidity, temperature, the number of subscribers, and water price). The results showed that the standard errors of ANFIS, ANFIS–GA, ANFIS–PSO, and SVM–SA were 0.669, 0.619, 0.705, and 0.578, respectively. Therefore, the hybrid model SVM–SA outperformed other models. The sensitivity analysis showed that of the parameters affecting drinking water consumption, the number of subscribers significantly affected the water consumption rate, while the average temperature was the least significant factor. Water price was a factor that could be easily controlled, but it was always one of the least effective parameters due to the low water fee.

Sodium hypochlorite has significant potential as a sanitation solution in hard-to-reach areas. Few studies have investigated the optimal electrolysis parameters for its production with volumes greater than 10 L. This study evaluated sodium hypochlorite production through electrolysis in a 22-L prototype and identified the optimal operating parameters. Tests were performed using graphite electrodes with areas of 68.4 cm² at the laboratory scale and 1 865.0 cm² at the prototype scale. A design for experiments with different operating times, chloride concentrations, and electric current intensities was developed. The optimal operating time, sodium chloride concentration, and current intensity at the laboratory scale were 120 min, 150 g of chloride per liter, and 3 A, respectively, leading to the production of 5.02 g/L of the disinfectant with an energy efficiency of 12.21 mg of Cl₂ per kilojoule. At the prototype scale, the maximum sodium hypochlorite concentration of 3.99 g of chloride per liter was achieved with an operating time of 120 min, a sodium chloride concentration of 100 g of chloride per liter, and a current intensity of 70 A, reaching an energy efficiency of 42.56 mg of Cl₂ per kilojoule. In addition, this study evaluated the influences of the chloride concentration, current intensity, and operating time on the production of sodium hypochlorite at the two scales, and formulated the equations showing the trends of sodium hypochlorite production and energy efficiency in the electrochemical systems. The 22-L prototype model for production of this oxidizing substance is promising for disinfection of large volumes of water in areas that are difficult to access.

Copula functions have been widely used in stochastic simulation and prediction of streamflow. However, existing models are usually limited to single two-dimensional or three-dimensional copulas with the same bivariate block for all months. To address this limitation, this study developed a mixed D-vine copula-based conditional quantile model that can capture temporal correlations. This model can generate streamflow by selecting different historical streamflow variables as the conditions for different months and by exploiting the conditional quantile functions of streamflows in different months with mixed D-vine copulas. The up-to-down sequential method, which couples the maximum weight approach with the Akaike information criteria and the maximum likelihood approach, was used to determine the structures of multivariate D-vine copulas. The developed model was used in a case study to synthesize the monthly streamflow at the Tangnaihai hydrological station, the inflow control station of the Longyangxia Reservoir in the Yellow River Basin. The results showed that the developed model outperformed the commonly used bivariate copula model in terms of the performance in simulating the seasonality and interannual variability of streamflow. This model provides useful information for water-related natural hazard risk assessment and integrated water resources management and utilization.

This study reported and discussed turbulence characteristics, such as turbulence intensity, correlation time scales, and advective length scales. The characteristic air–water time scale, including the particle chord time and length and their probability density functions (PDFs), was investigated. The results demonstrated that turbulence intensity was relatively greater on a rough bed in the roller length, whereas further downstream, the decay rate was higher. In addition, the relationship between turbulence intensity and dimensionless bubble count rate reflected an increase in turbulence intensity associated with the number of entrained particles. Triple decomposition analysis (TDA) was performed to determine the contributions of slow and fast turbulent components. The TDA results indicated that, regardless of bed type and inflow conditions, the sum of the band-pass ($T_u^{\prime }$) and high-pass ($T_u^{″}$) filtered turbulence intensities was equal to the turbulence intensity of the raw signal data (T_u). $T_u^{″}$ highlighted a higher turbulence intensity and larger vorticities on the rough bed for an identical inflow Froude number. Additional TDA results were presented in terms of the interfacial velocity, auto- and cross-correlation time scales, and longitudinal advection length scale, with the effects of low- and high-frequency signal components on each highlighted parameter. The analysis of the air chord time indicated an increase in the proportion of small bubbles moving downstream. The second part of this research focused on the basic properties of particle grouping and clustering.

A survey on bubble clustering in air–water flow processes may provide significant insights into turbulent two-phase flow. These processes have been studied in plunging jets, dropshafts, and hydraulic jumps on a smooth bed. As a first attempt, this study examined the bubble clustering process in hydraulic jumps on a pebbled rough bed using experimental data for 1.70 < Fr₁ < 2.84 (with Fr₁ denoting the inflow Froude number). The basic properties of particle grouping and clustering, including the number of clusters, the dimensionless number of clusters per second, the percentage of clustered bubbles, and the number of bubbles per cluster, were analyzed based on two criteria. For both criteria, the maximum cluster count rate was greater on the rough bed than on the smooth bed, suggesting greater interactions between turbulence and bubbly flow on the rough bed. The results were consistent with the longitudinal distribution of the interfacial velocity using one of the criteria. In addition, the clustering process was analyzed using a different approach: the interparticle arrival time of bubbles. The comparison showed that the bubbly flow structure had a greater density of bubbles per unit flux on the rough bed than on the smooth bed. Bed roughness was the dominant parameter close to the jump toe. Further downstream, Fr₁ predominated. Thus, the rate of bubble density decreased more rapidly for the hydraulic jump with the lowest Fr₁.

Clean drinking water is one of the United Nations Sustainable Development Goals. Despite significant progress in the water purification technology, many regions still lack access to clean water. This paper provides a review of selected water contaminants and their impacts on human health. The World Health Organization (WHO) guidelines and regional standards for key contaminants were used to characterise water quality in the European Union and UK. The concept of safe drinking water was explained based on the non-observed adverse effect level, threshold concentrations for toxic chemicals, and their total daily intake. Various techniques for monitoring water contaminants and the drinking water standards from five different countries, including the UK, USA, Canada, Pakistan and India, were compared to WHO recommended guidelines. The literature on actual water quality in these regions and its potential health impacts was also discussed. Finally, the role of public water suppliers in identifying and monitoring drinking water contaminants in selected developed countries was presented as a potential guideline for developing countries. This review emphasised the need for a comprehensive understanding of water quality and its impacts on human health to ensure access to clean drinking water worldwide.