Journal of Water Chemistry and Technology最新文献

Over the past two decades, many scientific journals have published a series of articles on environmental topics, which follow a similar pattern for studying adsorption on new materials. A review of more than 30 articles (as well as review practices), primarily focusing on the adsorption of synthetic organic compounds on new activated carbon materials, identifies the stages of scholarly research and highlights the main methodological and theoretical errors. These errors undermine the scientific value of these studies and reduce the experimental data presented within them to the status of scientific spam. The term “scholasticism” is used here in the sense of “pedantry,” “unified” nonessential research tasks, and excessive pondering over known or trivial matters. These issues point to gaps in the theoretical and practical training of young researchers. A typical feature of the scholastic approach is identified: instead of determining the conventional universal adsorption isotherm, the focus is on studying the influence of initial concentration, adsorbent weight, particle size, and contact time on adsorption efficiency—trends that are already well known to specialists. The epistemological significance and necessity of the stage of modeling experimental isotherms using both classical (Langmuir and Freundlich) and modern equations are critically evaluated. The paper presents a unique perspective on the role and objectives of modeling. The scholastic approach in kinetics relies on a formal description of rate laws, which predominantly ignore the physical nature of the adsorption of organic, especially aromatic, compounds, the hydrodynamics of flow, the fractional state of the adsorbent, the multistep nature of the process, and its limiting stage. The typical and characteristic inaccuracy of thermodynamic calculations in works exhibiting features of scholarly pedantry is highlighted, with the cause identified as the incorrect determination of the adsorption equilibrium constant, K_e. The paper gives specific methodological recommendations for environmental researchers, for whom adsorption-based water purification presents a new challenge, to avoid scholastic errors in their experimental endeavors and preserve the scientific value of their future work.

The presence of pollutants in water bodies compromises the aquatic ecosystem and public health. Crayfish waste is being discarded from the seafood market in large quantities annually. Crayfish shells can be valorized as biochar to remove water pollutants due to their availability and low cost. This paper review aims to highlight its preparation as an environmental-friendly adsorbent. Adsorption is a preferred process to remove various pollutants from water. The treatment methods and physicochemical properties of the derived biochar were highlighted, and the adsorption capacities of some model pollutants were compared and discussed. The calcium moieties and chitin in biochar aid in the adsorptive removal of target pollutants. Besides, the present challenges and future directions of crayfish shell biochar were presented to shed insight into practical applications in wastewater treatment.

Eliminating total colour (TC) from municipal wastewater is vital to ensure public health and environmental protection. This study examines the effectiveness of using aluminum chloride coagulant (ACC), Moringa oleifera seed (MOS), and Lactobacillus plantarum strain (LPS) in the removal of TC from municipal wastewater (MW). The central composite design (CCD) is utilized to evaluate the efficiency of every procedure and clarify the interdependent aspects involved in the removal of TC. An R² value above 95% indicates that the created CCD model is highly reliable. The LPS, ACC, and MOS processes have operational costs of 6.4, 9.5, and 1.3 $/m³, correspondingly. Ultraviolet-visible spectrophotometry verifies the efficiency of every process in TC elimination. Additionally, 95% of organic matter is found in the sediment of MOS, making it an excellent organic fertilizer. Acute toxicity tests on Daphnia magna demonstrate significant activity, confirming that the proposed methods effectively contribute to sustainable development by lowering toxicity levels of influent. Optimum operating conditions of MOS were found to be a pH of 7, dose of 2.5 g/L and time of 25 min. Also, the work not only advances our understanding of effective TC removal strategies but also emphasizes the broader environmental and ecological benefits of the investigated processes.

This study investigated the degradation of a mixture of chlorophenol solution using various Advanced Oxidation Processes (AOPs). At different optimized conditions obtained for trichlorophenol, dichlorophenol, and monochlorophenol individually, additional optimization was performed for treating mixed chlorophenols (Mi-CPs). In photocatalysis degradation, rapid and complete removal of Mi-CPs was reported at pH 6.0, TiO₂ dose of 0.25 g/L, and H₂O₂ concentration of 10.0 mM within 270 min. In the case of photo-Fenton’s process, the complete removal was observed in 12 min at pH 3.0, Fe(II) 0.5 mM, and H₂O₂ 10.0 mM. Different AOPs integrated methods were also employed towards efficient removal. Solar-derived processes exhibited enhanced degradation rates. Assessment of electrical energy per unit order indicated sonication or UV-driven processes as energy-intensive processes over solar processes. For instance, solar-Fenton’s process resulted in complete chlorophenol removal in 8 min, whereas solar catalysis resulted in degradation of the toxicant within 315 min, albeit slightly longer than UV-driven catalysis. Hence, solar processes can be considered as an environmentally friendly approach for treating industrial wastewater. Furthermore, the toxicity analysis conducted for treated effluent using a macrophyte reported the disruption of plant tissues and ultimately plant death, signifying the presence of chemical species obstructing the plant metabolism and growth.

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 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.

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.

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%.

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.