Journal of Water Chemistry and Technology最新文献

Industrial effluents from leather tanning activities often have a significant pollutant load that is difficult to biodegrade. Decontamination by conventional techniques is in some cases inefficient. The present work aims to study a novel process for enhancing the physical, chemical and microbiological quality as well as to reduce the pollutant load in tannery wastewater. In this process, we applied the tangential microfiltration technique using ceramic membranes with various pore sizes (0.2, 0.4, and 6 μm). According to the obtained results, this process significantly improved the physicochemical and microbiological parameters of the filtered wastewater as compared to the unfiltered one. It demonstrated good filtration efficiencies, in particular reducing (%) total chromium (83), BOD₅ (92), TSS (92), COD (98) and TC (100), which comply with Algerian standards for industrial discharges. Furthermore, ceramic membranes also reduced the intensity of the water colour during the retention step. These findings suggest that microfiltration using ceramic membranes is an efficient method for treating tannery wastewater.

The results of monitoring the indicators characterizing the organic compounds in a water supply source and water purified by the technology applied at the Dnipro Water Station (DWS) in Kyiv, namely, total organic carbon (TOC), chemical oxygen demand (COD), permanganate oxidability (PO), biochemical oxygen demand (BOD), and color are reported. The interactions between these indicators are estimated by using the Pearson correlation coefficients. It is shown that the best correlation of integral indices is observed for TOC and COD in the water supply source. The dependence of biodegradable organic carbon on TOC in the initial water is described by a high-quality model. A direct dependence on TOC in the input Dnipro water is observed for the concentration of chlorinated disinfection products in the purified water. The reasonability of using the total organic carbon concentration as a water quality indicator in a water supply source and potable water before chlorination is substantiated. It is proposed to introduce the indicator “total organic carbon” into state normative documents for obligatory control and coordination with international water quality requirements.

The residual sludge from urban wastewater treatment plants was utilized to prepare sodium bicarbonate-activated sludge biochar, which was then employed for removing Cd(II) from wastewater. In comparison with the inactivated sludge biochar (UBC), the activated sludge biochar (ABC) displayed an enhanced pore structure and increased graphitic nature. The adsorption experiments indicated that at pH 5 and an adsorbent dosage of 25 mg, both UBC and ABC achieved optimal removal performances for Cd(II). The coexisting ions of K⁺, Na⁺, Ca²⁺, Mg²⁺, Cl^– and ({text{NO}}_{3}^{ - }) were found to have negligible impact on removing Cd(II) by UBC and ABC, whereas Cu²⁺ and Pb²⁺ were observed to exert inhibitory effects on removing Cd(II) by both UBC and ABC. In the presence of humic acid (HA) at concentrations ranging from 0 to 25 mg/L, it was noted that HA exerted a beneficial effect on removing Cd(II) by UBC and ABC. The pseudo-second-order kinetic model and Langmuir model were found to effectively describe the process of Cd(II) removal by UBC and ABC. Meanwhile, the maximum adsorption capacities of UBC and ABC for Cd(II) were 73.30 and 196.47 mg/g, respectively. The Cd(II) removal by UBC and ABC was influenced by mechanisms such as electrostatic interactions, complexation, mineral dissolution−precipitation, and cation−π interactions. This further illustrated the efficacy of sodium bicarbonate as an activator in enhancing the Cd(II) removal from acidic wastewater by sludge-derived biochar.

This study investigates the effect of suspended matter concentration on the coagulation-flocculation and decantation treatment process of a low brackish water C(NaCl) = 1 g/L aiming for an effective optimization of the process using slightly brackish and turbid waters. Experiments were performed to detect the optimum performance of coagulant (Al₂(SO₄)₃) and flocculant on pH and turbidity removal from different bentonite solutions (0.5, 1, 1.5 and 2 g/L). The effects of coagulant dose, flocculant dose, decantation type, feed rate, speed, and time of rapid and slow mixing are also investigated. The medium mixing speed and the co-current lamellar decantation were adequate to improve turbidity removal to high efficiency (99.84%). Using a TE 600 pilot plant to test the optimum experimental conditions resulting from batch experiments, showed a high yield of turbidity removal confirming an application possibility of these experimental conditions in a real treatment plant.

In this sorption-based water treatment versatility study, cross-linked carboxymethyl starch phosphate (CCSP) hydrogel was reproduced via modification of native legume starch (NS) using sodium trimetaphosphate and sodium monochloroacetate. The swelling capacity and the point zero charge pH (pH_PZC) of the hydrogel were evaluated before the studies for the removal of turbidity and the physicochemical remediation of wastewater. The modification increased the swelling capacity from 156% (NS) to 473% (CCSP) and decreased pH_PZC from 5.66 (NS) to 4.77 (CCSP). This indicated enhancements in sorption and coagulation characteristics with the incorporation of negatively charged groups on CCSP. The equilibrium studies on turbidity removal (coagulation) using simulated turbid water showed that CCSP can serve as an efficient (>80%) coagulant at optimum conditions (pH: 6, agitation time: 15 min, temperature: 30°C, agitation speed: 50 rpm, and hydrogel dosage: 1000 mg/L). The treatment of wastewater samples with CCSP reduced turbidity (95–96%), chemical oxygen demand (42–46%), and total dissolved solids (12–21%), among other remediated conditions that indicated that the treated water was safer for discharge or utility.

A comprehensive study was conducted on the movement of a hydrophobic uncharged compound, o-chlorotoluene, in a model disperse system based on kaolin under the action of concentration gradients and an electric field, with and without the solubilizing solution of Triton X-100. The peculiarities of o-chlorotoluene transport were examined depending on the type of contamination—local (with the contaminated layer positioned between two pure layers of the dispersion) and uniform contamination of the entire dispersion. The impact of the electroosmotic flow character was considered (in a closed cell, with recirculating flow, or in an open cell, resulting in through-flow with diversion beyond the system) on the redistribution of o-chlorotoluene occurring during the treatment process is considered. In a closed cell, with local contamination of the dispersion, a symmetric distribution of o-chlorotoluene is formed, while preserving its initial amount. This is attributed to the electroosmotic flow and the counter hydrodynamic flows induced by it. In an open cell, even with the presence of narrow pores in the dispersion, the continuity of electroosmosis from the anode to the cathode is ensured, leading to the removal of o-chlorotoluene by the electroosmotic flow beyond the system. The efficiency of o-chlorotoluene removal depends on the type of contamination and the presence of a solubilizing agent. In the presence of Triton X-100, with local contamination of the dispersion, a decrease in the rate of o-chlorotoluene transport is observed compared to the treatment of the uniformly contaminated disperse system. Although the majority of the solubilized o-chlorotoluene, moving with the electroosmotic flow, is carried into the pre-electrode chamber, a portion of it enters the narrow space of pure kaolin or adsorbs onto the surface of its particles. In the absence of Triton X-100 solution, partial mechanical removal of the insolubilized o-chlorotoluene by the electroosmotic flow also occurs. Indicating that, its adsorption is partially reversible. This is related to the structure of kaolin, whose hydrophobic surface area, favorable for o-chlorotoluene adsorption under treatment conditions, is approximately 30–35%.

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.