Journal of Water Chemistry and Technology最新文献

Over these last years, there is no doubt that the conventional chemical flocculants commonly used for wastewater treatment have been a source of serious human health threats and environmental damage. Consequently, safe and eco-friendly substitutes are worth looking for and assessing. Within this line, flocculants derived from cactus namely, cladodes juice (CJ), powders of lyophilized (CLP) and oven-dried (CDP) cladodes, were developed as alternatives to the noxious synthetic ones. The flocculating activity of these three extracts was evaluated in treating a synthetic Disperse Blue-1 (DB-1) dye solution and a real industrial effluent loaded with heavy metals. A prominent DB-1 removal of up to 80% was achieved using CJ, CLP and CDP. Significant colour and turbidity reductions (94%) were attained using only 20 mg/L of CLP. Likewise, the cactus bio-flocculants complementing alum as a coagulant ensured an enhanced Zn removal from the industrial wastewater. For instance, both CLP and CDP allowed salient Zn uptake exceeding 99% against 69% using the CJ formula. The slight disparity in the flocculating activity between these three formulations could be ascribed to their preparation procedures affecting the integrity of their active agents (polysaccharides and chiefly polygalacturonic acid). Further, it is thought that the presence of hydroxyl (–OH) and carboxyl (–COOH) groups on this latter’s backbone confers the cactus extracts a notable flocculating ability regardless of the type of water pollutants. The plausible flocculation mechanisms for DB-1 molecules and Zn removal are assumed to be adsorption-bridging and adsorption-charge neutralization, respectively.

To determine ecological and health risk assessment of the Berdan and Göksu river waters, principal physical and biochemical variables were measured monthly between September 2021 and August 2022 in the Berdan and Göksu river basins. Ecological risk assessment of the studied river basins indicated that both the Berdan and Göksu river waters were contaminated by phosphorus. Potential health risk assessment of the Berdan and Göksu river basins showed that the calculated Health Quotient values in the two visited stations in the Berdan river exceeded 0.1 indicating low cancer risk for both adults and children whilst one visited station in the Göksu River basin showed low cancer risk for children. The health risk assessment also indicated that the Health Quotient values calculated for children were consistently higher than those calculated for adults, showing that children were potentially at higher risk for health hazards from nitrate.

The historical development of viewpoints on the effect of solar activity on climatic phenomena is analyzed as possible mediators in the generation of water quality changes. The quality of water delivered to the water treatment facilities of the Dnipro Water Supply Station (DWSS) in Kiev after the Kyiv Reservoir is studied. It is shown that such parameters as color and oxidability are caused by organic substances, the presence of which in water correlates with solar activity in a certain way. Using cross-correlation and wavelet analyses, the existence of a moderate correlations between solar activity and turbidity, iron and manganese content, permanganate oxidability, and total organic carbon content is shown. These parameters are likely to be varied due to climatic conditions and water supply source hydrology changes, inclusively, in the balance of water inflow to the Kyiv Reservoir.

Elevated concentrations of heavy metals in wetlands can contaminate surface water, posing hazards to human health and ecological balance. Given increasing urbanization and activities in places like Algeria, it is crucial to closely monitor and effectively control heavy metal pollution in surface water. This study proposes the use of artificial neural networks (ANN) and various indicators to comprehensively assess metal contamination in Algerian surface waters and its implications for public health. Sixteen water samples were collected for the composition analysis and source identification. Measurements indicated that several areas exceed the World Health Organization (WHO) limits for four metals. Methods such as the heavy metal evaluation index (HEI) and heavy metal pollution index (HPI) were employed to assess pollution levels. Results showed that over 99% of samples exhibited significant pollution according to HPI, with 60% showing elevated pollution levels by HEI, highlighting substantial contamination risks. Principal component analysis (PCA) revealed that the first two components accounted for 93.540% of total variation, with subsequent components contributing 6.459% or less. PCA 1 and PCA 2, representing 49.084 and 44.456% of variability, respectively, were identified as primary components, while PCA 3 and PCA 4 each contributed less than 5.015 and 1.444% to total variance. The study demonstrated minimal error values and R² values exceeding 0.5 during the testing of heavy metal models, indicating robust performance. Overall, this study underscores the prevalence of elevated metal levels in water bodies, providing comprehensive insights into heavy metal contamination in Algerian basins to assist environmental management decisions and protect public health.

Fly ash is the primary residue produced in huge amounts by coal combustion in thermal power plants, which needs to be utilized appropriately. In this connection, an experimental study was conducted with fly ash alone and in combination with soil for the treatment of simulated dumpsite leachate in constructed wetland (CW) (vertical flow) systems containing Canna + Typha plants. The study revealed that the fly ash + soil mixture as a CW substrate showed better removal efficiency of chemical oxygen demand (COD), phosphate (({text{PO}}_{4}^{{3 - }})), total nitrogen (TN), and chloride (Cl^–) by 97.3, 99.4, 94.5, and 89.6%, respectively, in comparison to the fly ash alone which was shown to yield the corresponding values of 88.5, 94.1, 84, and 73.2% of the efficiency in the removal of these pollutants from simulated dumpsite leachate.

A self-floating amphiphilic biosorbent (SFAB) was prepared by dispersing the plasma-modified water hyacinth (WH) (Eichhornia crassipes) fibers on the beeswax support. The synthesis process takes advantage of the functionalising properties of plasma with polar groups (–OH, –CO, –COOH) and the binding effect of beeswax. The characteristics of the obtained biosorbent exhibited significant changes in surface chemistry and roughness confirmed by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and energy dispersive X-ray spectroscopy (EDX). The resulting functionalised material offers appropriate anchoring sites for pollutants leading to a biomaterial with hydrophilic and lipophilic properties. The removal performance of the SFAB outperforms the natural biomass fibers taking alone, with an uptake capacity of 20.83 mg/g for merbromin (MB) (50 mg/L) and 19.90 mg/g for Green Naphthol B (GNB) (50 mg/L), based on the successfully fitted general-order kinetic model. The effects of some key adsorption parameters were optimised, and the equilibrium data (298–323 K) were best fitted by the Liu isotherm reaching 47.20 and 36.40 mg/g of uptake amounts for MB and GNB, respectively at 298 K. The removal mechanism is governed by π–π interplay, hydrophobic interaction, and hydrogen bonding effects.

Domestic wastewaters have a significant concentration of nutrients that can be utilised as alternative sources of phosphorus and nitrogen for agriculture applications. Chemical precipitation is one of the processes found to be an efficient way for nutrient recovery from various wastewater feedstock. However, not all nutrients are in a form that can be readily recovered. Therefore, a pre-treatment process may be necessary for an efficient recovery of nitrogen and phosphorus. In this research, acid hydrolysis was performed as pre-treatment to release phosphorus from synthetic septage into soluble forms for the subsequent precipitation as struvite (MgNH₄PO₄·6H₂O) which is known as a slow-release fertiliser for application in agriculture. Results show that acid hydrolysis increases the phosphate concentration (PO₄-P) to 148.07 ± 1.78 from 61.50 ± 0.07 mg/L, showing the potential of hydrolysis as pre-treatment to efficiently recover nutrients in the form of struvite. The result can inform further research to develop efficient processes for the recovery of nutrients from domestic wastewater.

The study investigates the adsorption of heavy metals (HMs), specifically Cd(II) and Co(II), from aqueous solutions using synthesized iron oxides with layered structures and surface groups of a basic nature: goethite α-FeO(OH), lepidocrocite γ-FeO(OH), and ferrihydrite Fe(OH)₃. The results indicate that these crystalline materials are effective in adsorbing heavy metals within pH ranges typical of natural aquatic environments (7.5). We determined the conditions for extracting heavy metals, examining the effect of pH in aqueous solutions, ionic strength, adsorbent dosage, and major components of natural waters. The results show that the majority of HM ions are extracted within the first 30 min of contact between the aqueous solution and the solid phase of the adsorbents, with adsorption equilibrium being reached for iron-containing adsorbents in approximately 4 h. To account for the relative distribution of HM species in aqueous environments with varying pH values, we calculated the distribution of these species for the concentrations studied in model water solutions, enabling an evaluation of the extraction mechanism. The adsorption of Co(II) and Cd(II) is primarily driven by the interaction of their cationic forms with ferrinol surface groups of the studied iron-containing minerals through chemisorption from aqueous solutions within the investigated pH range. The adsorption limits for goethite and ferrihydrite are nearly identical, while those for lepidocrocite are significantly lower, which can be attributed to their structure and the availability of active adsorption sites. The shape of the adsorption isotherm curves is also quite similar across the entire concentration range. Based on the data obtained regarding the adsorption efficiency of Cd(II) and Co(II), which are among the most challenging cations to remove using adsorption methods, the synthesized goethite and ferrihydrite can be recommended as cost-effective and efficient materials for the purification of natural waters contaminated with heavy metals.

Small rivers and other surface and groundwater sources form the basis for the functioning of river basin systems, shaping streamflow, providing water supply for rural areas, and supporting biodiversity. Local surface and groundwater sources are extremely sensitive to anthropogenic impacts and climate change. Changes in the quality and quantity of water in these sources are a primary factor influencing their use for various purposes, objects, methods, and technical conditions. Therefore, the research aimed to assess the quality of natural waters in the southern part of the Mohyliv-Podilskyi district, within the basin of the small river Kotlubayevka (a right tributary of the Dniester River). The primary research methods were analytical and statistical. The analytical method was used to determine the chemical composition of water samples according to standardized procedures. The statistical method was used to find out the reliability of measurement results and to provide a generalized assessment of water quality. Experimental results were processed for water samples based on ecological and sanitary criteria from eight potential sources of economic use located along the slopes of the Dniester and Kotlubayevka river basins, ranging from elevations of 215–206 to 78–55 m a.s.l. According to the ecological classification of surface water quality, the studied sources are classified as fresh oligotrophic (class I), and based on ion composition criteria, they are categorized as bicarbonate waters of type I (({text{HCO}}_{3}^{ - }) > Ca²⁺ + Mg²⁺). The study identified a trend of water source contamination in the research area concerning copper, iron (Fe_total), and saprophytic bacteria Escherichia coli. A generalized ecological assessment of water was calculated using block indices for salinity composition, ecological-sanitary, and specific toxic indicators, which ranged from 2.33 to 3.00 along the slope above the river currents. The results indicate that the quality of the studied water sources ranges from “very good,” “clean,” to “good,” “fairly clean.” However, based on the block index for specific toxic indicators, the water quality tends to approach “fairly good” or “slightly polluted.” Among the water contaminants, elevated levels of Fe_total, Cu²⁺, and E. coli primarily contribute to the deterioration of water quality and safety. Iron and copper contamination should be regarded as a natural factor, while microbiological contamination by E. coli should be considered a result of anthropogenic impact. The obtained research results impose limitations on the economic use of certain water sources, particularly in agricultural production.

Removing relatively concentrated salicylic acid (SA) from pharmaceutical aqueous waste was performed using unmodified and modified commercial cationic exchange resin (Amberlite 200C). The modification of the resin involved grafting functional molecules onto the aromatic ring through classical organic reactions or by irreversible adsorption into the resin’s structure. The nitro group (({text{NO}}_{2}^{ + })) was synthesized by combining nitric and sulfuric acids and then attached to the resin matrix through nitration. Meanwhile, 2,4-dinitrophenyl hydrazine (DNPH), tributyl phosphate (TBP), and ammonium (({text{NH}}_{4}^{ + }) ) were irreversibly adsorbed onto the resin matrix via immersion. Consequently, the unmodified resin achieved a 21% elimination of the initial SA, whereas modified resins significantly increased the elimination yield. Specifically, ({text{NH}}_{4}^{ + }) and DNPH-modified resins achieved SA elimination rates of 51.94 and 41.5%, respectively. However, the use of TBP and ({text{NO}}_{2}^{ + }) modified resins resulted in negligible SA removal. The optimal conditions for operation were determined to be: pH 5.5, temperature 21°C, and a contact time of 20 min.