Search Results (118)

This study aimed to investigate phytoplankton dynamics and water quality at three drinking water intakes (Duchang, Hukou, and Xingzi) in Poyang Lake through monthly monitoring from May 2023 to April 2024. The results showed that a total of 168 species of phytoplankton were identified in nine phyla, and there were significant spatial and temporal differences in the abundance of phytoplankton at the three waterworks intakes, with a spatial trend of annual mean values of Duchang > Xingzi > Hukou and a seasonal trend of summer and autumn > spring and winter. The dominant species of phytoplankton in the waterworks intakes of the three waterworks also showed obvious spatial and temporal differences. Cyanobacteria (particularly Pseudanabaena sp. and Microcystis sp.) dominated the phytoplankton communities during summer and autumn, demonstrating significant water degradation potential. In contrast, Cyclotella sp. prevailed in winter and spring assemblages. Based on water quality assessments at the three intake sites, the Duchang County intake exhibited year-round mild eutrophication with persistent mild cyanobacterial blooms (June–October), while the other two sites maintained no obvious bloom conditions. Further analyzing the toxic/odor-producing algal strains, the numbers of dominant species of Pseudanabaena sp. and Microcystis sp. in June–October in Duchang County both exceeded 1.0 × 10⁷ cells·L⁻¹. It is necessary to focus on their release of ATX-a (ichthyotoxin-a), 2MIB (2-Methylisoborneol), MCs (microcystins), etc., to ensure the safety of the water supply at the intake. Building upon these findings, we propose a generalized algal monitoring framework, encompassing three operational pillars: (1) key monitoring area identification, (2) high-risk period determination, and (3) harmful algal warnings. Each of these is substantiated by our empirical observations in Poyang Lake. Full article

In this study, activated carbon, iron-based waterwork sludge, and polyethyleneimine (PEI) were employed as the primary raw materials to synthesize the composite PEI@MMI(800) under the optimized conditions identified through experimental investigations. The resulting composite was employed as an adsorbent for static Cr(VI) adsorption tests. The results demonstrated that increasing the pH from 2 to 9 significantly decreased the Cr(VI) adsorption capacity from 41.09 mg/g to 15.75 mg/g. The adsorption process was well described by both the pseudo-second-order kinetic model and the Langmuir isotherm model. Thermodynamic analysis revealed that the adsorption process was spontaneous and endothermic in nature. The presence of anions (Cl⁻, SO₄²⁻, and PO₄³⁻) negatively impacted Cr(VI) adsorption, with their inhibitory effects following the order Cl⁻ < SO₄²⁻ < PO₄³⁻. Moreover, higher concentrations of these anions led to reduced Cr(VI) adsorption efficiency. After six cycles of use, PEI@MMI(800) retained 79.80% of its initial Cr(VI) adsorption capacity, indicating a loss of 20.20%. Based on the comprehensive characterization of the adsorbent and the results of the Cr(VI) adsorption tests, it was concluded that the removal of Cr(VI) by PEI@MMI(800) involved a combination of electrostatic adsorption, chelation of Cr(VI) by PEI, and reduction of Cr(VI) to Cr(III). Full article

This work explores the relationship between water quality and public trust in their water supply, in an arsenic-affected region of Serbia. The results from an online public survey are presented and subjected to Pearson’s correlation, cluster analysis, and principal component analysis. In general, survey respondents in settlements with known arsenic issues had a poor opinion on the quality of their tap water. This poor opinion was underlined by their consumption of bottled water, with more than 43% of responders purchasing at least 5 L of bottled water a week. In addition to the great economic cost, the relatively low plastic recycling rate in Serbia means that this also has a very negative effect on the environment, as most of the plastic bottles are sent to landfill, to degrade slowly into microplastics, whilst leaching a variety of chemical contaminants into the surroundings. In the area studied, the poor public opinion of the water quality is a realistic reflection of water at the tap. Although significant, the additional environmental pollution from bottled water consumption should nonetheless be of secondary consideration in comparison to the health risks associated with chemical contaminants in the study area, with local waterworks requiring significant financial assistance if they are to meaningfully improve tap water quality. Full article

In this study, an effective composite material, manganese-modified magnetic dual-sludge biochar (Mn@MDSBC), was developed for the adsorption of ciprofloxacin hydrochloride (CIP). This composite was prepared by means of a simple one-pot method, which involved the pyrolysis of iron-based waterworks sludge (IBWS) and paper mill sludge (PMS) loaded with manganese (Mn) under controlled conditions in a nitrogen atmosphere. The synthesized Mn@MDSBC was subjected to a comprehensive suite of characterization approaches, which included N₂ adsorption–desorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Subsequently, static adsorption tests were conducted to investigate how different factors, including the initial solution pH, reaction time and temperature, CIP concentration, and ionic strength influence the adsorption of CIP by Mn@MDSBC. Mn@MDSBC had the maximum CIP adsorption capacity of 75.86 mg/g at pH 5, among the pH values ranging from 3 to 9. The pseudo-second order model provided the best description of the adsorption process, while the experimental data aligned more closely with the Langmuir equation than with the Freundlich model, indicating monolayer adsorption. The adsorption process was found to be non-spontaneous and exothermic according to thermodynamic analysis. The presence of Cl⁻ and SO₄²⁻ enhanced CIP adsorption, while PO₄³⁻ weakened it. After five cycles of reuse, Mn@MDSBC experienced a 17.17% loss in CIP adsorption capacity. The primary mechanisms for CIP removal by Mn@MDSBC were identified as physical and chemical adsorption, hydrogen bonding, and π-π stacking interactions. In summary, the study underscores the high efficiency of Mn@MDSBC as a composite material for CIP adsorption, highlighting its potential for application in wastewater treatment processes. Full article

The persistent challenge of achieving cost-effective total phosphorus (TP) removal in wastewater treatment necessitates innovative coagulant development. While polyaluminum chloride (PAC) demonstrates efficacy in eliminating total nitrogen (TN), ammonia nitrogen (NH₄⁺-N), suspended solids (SSs), and pH stabilization, its limitations in attaining economical TP removal remain unresolved. This study introduces a novel FeSO₄-Al₂(SO₄)₃ composite coagulant to address PAC’s shortcomings through systematic formulation optimization. Utilizing single-variable experiments and response surface methodology (RSM), we determined the optimal reagent combinations under simulated high-efficiency sedimentation tank conditions. The results revealed that the FeSO₄-Al₂(SO₄)₃ composite achieved a TP removal efficiency approximately 40% greater than the PAC at equivalent dosages. A cost–benefit analysis indicated an approximate 50% reduction in the chemical expenditure relative to conventional PAC-based systems. The optimized formulation demonstrated synergistic effects between the Fe²⁺ and Al³⁺ ions, enhancing the charge neutralization and sweep flocculation mechanisms. These findings establish FeSO₄-Al₂(SO₄)₃ as a technically and economically viable alternative for TP-centric wastewater treatment, with implications for process sustainability. Further investigations should validate the long-term operational stability across diverse water matrices and assess the environmental impacts of residual metal ions. Full article

Shallow lakes are important drinking water sources, but are easily affected by wind. Turbidity is an indicator that fluctuates dramatically with changes in wind and is affected not only by the instantaneous wind speed but also by the wind direction, duration, etc. The Weibull distribution was introduced to describe the distributions of the wind conditions and turbidity during a seasonal period. The relationship between the mean wind-power density and the corresponding turbidity reached 0.8, which showed a relatively strong correlation. A turbidity prediction model was built by the random forest algorithm and was fed with the mean wind-power density and temperature. The results indicated that nearly half of the test samples had REs less than 20%, which was enough for waterworks to adjust the dosage in advance. The findings can be used to develop turbidity prediction models using meteorological forecast data and provide a reference for waterworks with shallow lakes as sources. Full article

To estimate the sources of polycyclic aromatic hydrocarbons (PAHs) and their contributions to the total PAH emissions, more than 40 PAHs and organic tracers in PM_2.5 collected in 3 cities of Japan were measured and a positive matrix factorization (PMF) model analysis was performed. During the warm season, high PAH concentrations were detected in Nagoya, which is located in the port area. Total PAHs were classified into five sources: biomass combustion, semivolatile PAHs, and ship and industrial emissions, which were major, and road traffic and plastic combustion, which were minor. Analysis of the ship and industrial emissions revealed that the concentrations of these sources in the severe PAH pollution event in Nagoya exceeded 15 ng/m³ and the significant contribution exceeded 80%. In addition, PAHs indicating a risk of carcinogenicity, such as 1 to 2B by IARC and 1 to B2 by U.S. EPA, had the highest contribution to this factor among the five factors such as biomass burning and ship and industrial emissions. Our results suggest that sources of high PAH emissions exist in the port areas of Nagoya. The PMF analysis performed in this study, using combustion organics as indicators, is expected to aid other countries and regions in identifying the sources of PAHs for their effective control. Full article

Nitrates (V) in drinking water are harmful to human health and are a probable carcinogen. Nitrates (V) in drinking water are responsible for the formation of methaemoglobin, which causes hypoxia, cyanosis, collapse and even death. Newborn babies and infants up to six months of age are most at risk. For this reason, a European Union directive was introduced in 1991 to protect waters from pollution caused by nitrogenous fertilisers of agricultural origin, restricting their use. The aim of the study was to analyse the content of nitrogen compounds (ammoniacal nitrogen, nitrates (III and V)) in water samples from selected rural waterworks in Tłokinia Wielka. Analyses were performed using spectrophotometric methods. The results showed that excessive levels were present in the tap water from public water supplies, which are regularly monitored by the State Sanitary Inspectorate and water supply companies. Full article

The discharge of nutrients and organic pollutants is increasing at an alarming rate, driven by the rapid development of human activities. This growing pollution is contributing to significant environmental issues, including eutrophication, making the treatment of wastewater essential before its release into the environment. Prior to being released into water bodies, treated wastewater must undergo rigorous laboratory analysis. For this reason, analysis using standard methods was carried out at the Laboratory Waterworks in Debrecen on multiple samples taken from various wastewater treatment plants in Hungary. The primary objective of this research was to assess the quality of effluents from (14) wastewater treatment plants and investigate their efficiency by measuring various physicochemical and microbiological parameters as indicators. The microbiological indicator monitored was the heterotrophic count (HPC) by estimating its total number. The results revealed that substantial removal efficiencies were demonstrated by parameters including total nitrogen (TN), chemical oxygen demand (COD), and biochemical oxygen demand (BOD₅), with reductions averaging 91%, 92%, and 87%, respectively. However, the reduction in nitrogenous compounds (nitrite NO₂⁻ and nitrate NO₃⁻) was limited, indicating areas for process improvement. Recommendations for enhancing treatment efficiency are proposed to optimize the overall performance of the wastewater treatment plants. Full article

Floods are the climate hazard that has the greatest socio-economic and territorial impact on the world. The root causes of these events are atmospheric and hydrological phenomena. However, human action usually aggravates their effects, as it alters the normal functioning of the river courses and water flows. The installation of road, rail and hydraulic infrastructures in a floodplain with no prior calculation or appropriate adaptation exacerbates the negative consequences of floods, increasing the extension of the flooded area and the height of the flood waters. This study addresses the problem of the barrier effect generated, on the one hand, by the layout of the N-332 road, as it is built at the same level as the ground, hindering the flow of overflowing water during episodes of flooding, and on the other hand, the channelling wall of the Segura River in the final stretch of its mouth, in the towns of San Fulgencio and Guardamar del Segura. These elements have aggravated flooding in this area. In order to analyse the consequences of the flood, IBER (v.3.3) software has been used to model a flood with similar effects to that of the episode of September 2019. The current situation has also been analysed with two openings in order to determine the effects that a future flood would have. After analysing the results, a proposal to correct the barrier effect of the N-332 road and the new channelling wall of the River Segura has been elaborated upon and then modelled. The results are positive and effective in reducing the negative effects of floods in the lower basin of the River Segura. Full article

Water scarcity is a global challenge faced by millions of people, and it has a negative impact on the ecosystem, public health, and financial stability. Water demand and supply management becomes critical, especially in areas with limited access to clean, safe water. Wastewater and water treatment infrastructure is essential for maintaining environmental integrity and protecting human health. However, water treatment plants in South Africa face various complex obstacles brought on by institutional setups, practical limitations, and environmental concerns, including water quality. This study investigated the institutional arrangements, operational challenges, and environmental concerns that water and wastewater treatment plants face in the Vhembe District Municipality, South Africa. A qualitative study was conducted in Limpopo province, where employees from 12 water and wastewater treatment plants were interviewed, and the data were analyzed thematically. The data were arranged into five major themes using thematic analysis: understanding water and wastewater treatment systems, educational and demographic profile, water quality assessment, operational performance and regulatory compliance, and water volume in waterworks plants. Staff attitudes, institutional and operational challenges, and the current condition of treatment plants were all comprehensively portrayed using Ostrom’s IAD Framework. It was found that workers generally understand water treatment processes, but inconsistencies and a lack of transparency in monitoring water quality were noted, with many parameters from SANS 241 not being tested consistently. A significant educational gap among workers was also observed. Insufficient capacity, load-shedding, limited resources, and inadequate infrastructure prevented treatment plants from meeting daily water needs, worsened by institutional and socio-economic factors. Similar challenges were noted in countries like China, Ethiopia, India, Pakistan, Malaysia, Brazil, and Libya. To enhance water management efficiency and compliance, the study recommends more training, standardized procedures, proactive maintenance, and stakeholder involvement. Full article

The subject of investigation presented in this article is a filling and draining system of the ship lock installed in the Gabčíkovo Waterworks. This article describes the operation and construction of the special regulation segments, i.e., the check gates that are situated in the ship locks. After the failure and replacement of the original check gate with the new, improved one, the strain gauge sensors were applied to the new check gate in order to determine stress distribution on the segment surface as well as the loading of the actuating arms. The application method and application places of the strain gauge sensors are described in detail. The performed measurements detected the occurrence of additional motional resistances during the opening and closing of the check gate. These resistances caused a partial non-functionality of the original check gate actuating mechanism. Full article

Preventive Maintenance (PM) is a periodic maintenance strategy that has great results for devices in extending their lives, increasing productivity, and, most importantly, helping to avoid unexpected breakdowns and their costly consequences. Preventive maintenance scheduling (PMS) is determining the time for carrying out PM, and it represents a sensitive issue in terms of impact on production if the time for the PM process is not optimally distributed. This study employs hybrid heuristic methods, integrating Genetic Algorithm (GA) and Tabu Search (TS), to address the PMS problem. Notably, the search for an optimal solution remained elusive with GA alone until the inclusion of TS. The resultant optimal solution is achieved swiftly, surpassing the time benchmarks set by conventional methods like integer programming and nonlinear integer programming. A comparison with a published article that used metaheuristics was also applied in order to evaluate the effectiveness of the proposed hybrid approach in terms of solution quality and convergence speed. Moreover, sensitivity analysis underscores the robustness and efficacy of the hybrid approach, consistently yielding optimal solutions across diverse scenarios. The schedule created exceeds standards set by waterworks experts, yielding significant water and electricity surpluses—16.6% and 12.1%, respectively—while simultaneously matching or surpassing total production levels. This method can be used for power plants in private or public sectors to generate an optimal PMS, save money, and avoid water or electricity cuts. In summary, this hybrid approach offers an efficient and effective solution for optimizing PMS, presenting opportunities for enhancement across various industries. Full article

The awareness of the concept of the “Circular Economy” is motivating scientists to convert drinking water treatment plant by-products, which are based on aluminum waste, into a valorized material for wastewater treatment. Alum sludge from a local waterworks plant in Egypt was collected and dewatered using chitosan-coated magnetic nanoparticles. The role of the conditioned sludge in wastewater treatment was then examined. Chitosan (Ch) augmented with magnetite nanoparticles (MNs), labeled as ChMNs, was prepared by means of a simple co-precipitation route with mixing ratios of 1:1, 2:1, and 3:1 of chitosan and magnetite nanoparticles to form the ChMN catalyst. The ChMNs were shown to beneficially enhance alum sludge conditioning and dewaterability. The conditioned and dried aluminum-based sludge (AS) loaded with ChMNs was then used as a source of Fenton’s catalyst for Synozol Red-KHL textile dyeing wastewater. The characteristics of the AS-ChMN sample were investigated using Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The photocatalytic activity of the AS-ChMN composite was assessed by examining its diffuse reflectance spectra (DRS). Response surface methodological analysis was applied to optimize the operational parameters in order to reduce the use of chemicals and improve dye oxidation to form a complete (99%) dye oxidation strategy. The experiments demonstrated that the optimal operating parameters included doses of 1.5 g/L and 420 mg/L for AS-ChMNs and hydrogen peroxide, respectively, as a source of Fenton’s reaction at a working pH of 3.5. Kinetic and thermodynamic analyses for potential full-scale applications were conducted, showing the reaction to be exothermic and spontaneous in nature and following second-order reaction kinetics. Hence, the novelty of this work lies in the introduction of conditioned and dewatered alum sludge waste as a photocatalyst for textile dye effluent oxidation, which could be considered a “win–win” strategy. Full article

A series of nanocrystalline iron oxide samples (M1–M5) which differ from each other in average crystallite size (from 26 to 37 nm) was studied. The raw material was nanocrystalline iron with an average crystallite size equal to 21 nm promoted with hardly reducible oxides: Al₂O₃, CaO, K₂O (in total, max. 10 wt%). Nanocrystalline iron was subjected to oxidation with water vapor to achieve different oxidation degrees (α = 0.16–1.00). Metallic iron remaining in the samples after the oxidizing step was removed by etching. Magnetic resonance spectra of all samples were obtained at room temperature. All resonance lines were asymmetric and intense. These spectra were fitted by Lorentzian and Gaussian functions. All spectral parameters depend on the preparation method of the nanoparticles. We suppose that the Lorentz fit gives us a spectrum from larger agglomerated sizes whereas the Gaussian fit comes from much smaller magnetic centers. For the nanocrystalline samples with the largest size of iron oxide nanocrystallites, the highest value of total integrated intensity was obtained, indicating that at smaller sizes, they are more mobile in reorientation processes resulting in more settings of anti-parallel magnetic moments. The magnetic anisotropy should also increase with the increase in size of nanocrystallites. Full article