Journal of Water Chemistry and Technology最新文献

Waste rocks obtained from mining operations are typically stockpiled due to the lack of their economic value. This practice resulted in significant land occupation and potential for secondary pollution risks due to the lack of probability of leaching. The present study explores the possible utilization of waste rocks as a novel adsorbent for treating F⁻ enriched groundwater. Shale, a coal mine waste was chemically modified by ferrous chloride in a 3 : 1 ratio. Optimization of the adsorption process was done by performing batch adsorption. Surface morphological characterization of the adsorbent was performed by scanning electron microscopy (SEM), energy-dispersive X-ray (EDS), X-ray diffraction (XRD) and Fourier transform infrared spectrophotometer (FTIR). The best results were obtained when 100 mg/L was used to defluoridate contaminated water for 60 min at neutral pH. The efficiency of management was 32% removal at 10 ppm fluoride contamination. Post-treatment adsorbent can be utilized in brick formation to rule out any possibility of secondary/tertiary contamination.

Spirulina is extensively studied among cyanobacteria. It has been used as a source of protein since ancient times. The present investigation addressed the cultivation of Spirulina in kitchen wastewater with the aim of water remediation. Water quality parameters were evaluated by analysing physicochemical parameters both before and after the growth of Spirulina. The microscopic inspection revealed the presence of Spirulina exhibiting spiral and helical shapes. Water quality parameters, including total suspended solids, total dissolved solids, chlorides, sulfates, phosphate, total hardness, and total alkalinity, were found to be high in the wastewater before the cultivation of Spirulina. In addition, it had very acidic conditions with a pH range of 4.5 to 6.0. The cultivation of Spirulina resulted in favourable changes in various chemical parameters. Specifically, the total suspended solids, total dissolved solids, chlorides, sulfates, phosphate, total hardness, and total alkalinity decreased while the sodium level increased. Further, it increased the pH level to the neutral range. According to the findings of this study, it can be inferred that cultivating Spirulina in wastewater positively altered the physicochemical characteristics of the wastewater and resulted in an increased yield of Spirulina.

This study aims to evaluate the performance of a bioreactor at an upflow packed bed with synthetic wastewater containing phenol under continuous operation. The used microorganism was formed by a mixed culture isolated from a wastewater treatment plant. The mean residence time (t_m = 3.92 h) in the bioreactor was obtained experimentally by following the tracer NaCl 0.5 M concentration in a continuous effluent stream. For the first time, we calculated the superficial velocities of liquid (u_L) and gas (u_G) in a three-phase medium (air-water-sand) in the absence of biomass; these velocities vary from 5.40 × 10^–3 to 5.84 × 10^–3 and from 0.36 × 10^–3 to 3.67 × 10^–3 m/s, respectively. Afterwards, the effects of airflow (AF = 10, 20, and 30 L/h), liquid flow rates (LF = 3, 5, and 9 mL/min), and initial phenol concentration (C₀ = 100, 200, 300, 500, and 700 mg/L) on the biodegradation rate of phenol were studied. The results indicate that the rate of continuous biodegradation increases with the initial phenol concentration and decreases both with the AF and LF rates. The biofilm concentration uniformly increases with increasing the height of the sand bed. The process in the continuous model also contributed to a high elimination efficiency of 100%.

This study investigated water recovery with the treatment of leather industry processes wastewater (washing, pickling, and degreasing units) using coagulation, ultraviolet/persulfate (UV/PS) treatment, and nanofiltration processes. Coagulation studies were carried out using alum as the coagulant, and the highest chemical oxygen demand (COD) removal efficiency was obtained at pH 7 for all the wastewater. The highest COD and total organic carbon (TOC) removal were 80.9 and 50.5% in the wastewater washing unit (({{{text{S}}}_{{text{2}}}}{text{O}}_{8}^{{2 - }}) : 8 g/L, pH 7) and 76.5 and 96.1% in the wastewater degreasing unit (({{{text{S}}}_{{text{2}}}}{text{O}}_{8}^{{2 - }}) : 16 g/L, pH 6) using UV/PS oxidation, respectively. High COD and TOC removal could not be achieved with UV/PS oxidation in the wastewater pickling unit. In the studies performed with NP030 nanofiltration membrane after UV/PS oxidation, the highest permeability and COD removal was achieved at pH 7 under 4 × 10⁵ Pa pressure in wastewater washing and degreasing units. After 75 min of nanofiltration at pH 7 in washing and degreasing units, the total filtrate amount was 39.8 and 42.3 L/m² h, respectively. COD concentration in the wastewater washing unit decreased from 4434 to 138 mg/L, while it decreased from 5833 to 212 mg/L in the wastewater degreasing unit with coagulation, UV/PS processing, and nanofiltration. As a result, the treatment of leather industry wastewater through separate streams with coagulation, UV/PS, and nanofiltration, washing, and degreasing unit wastewater provides very high COD removal. Also, it has been shown impossible to treat the pickling unit wastewater by UV/PS oxidation.

The release of various pollutants into the environment necessitates monitoring their spreading in soils, developing strategies to prevent their transfer into water bodies, as well as identifying and conducting priority detoxification of those local contaminants that, due to their chemical and physical properties and the structure of polluted soils, pose the greatest risks. This article develops a theoretical theoretical basis and methodology for studying the diffusion transport of toxicants. Using a model dispersion of kaolin contaminated with o-chlorotoluene, the study investigates the diffusion rates of hydrophobic organic compounds in natural concentrated disperse systems. The experiments were conducted at various temperatures of the dispersion medium, both in the absence and presence of surfactant Triton X-100. A comparison was made between the temporal concentration distribution profiles of o-chlorotoluene in areas adjacent to the localized pollution zone and the results of theoretical calculations based on the Fick equation. Diffusion coefficients of the contaminant in the concentrated disperse system were calculated under the considered conditions of its spread. The obtained diffusion coefficients of o-chlorotoluene in the kaolin dispersion are significantly lower than the diffusion coefficients of organic hydrophobic compounds in aqueous media. This is attributed to the fine porosity of the model system used, the tortuosity of pores, and the interaction of o-chlorotoluene molecules with the dispersion surface. The structural factor and the presence of contact surface also contribute to a more pronounced reduction in the diffusion coefficient with decreasing temperature than would be expected due to the decrease in the energy of particle thermal motion and the increase in viscosity of the pore solution. The decrease in diffusion rate due to the formation of micellar aggregates of o-chlorotoluene with Triton X-100, caused by their larger sizes compared to individual molecules, is compensated by hydrophilization and the conversion of pollutants into a mobile state.

The discharge of synthetic surfactants into the environment poses a serious threat to natural water bodies, as even at relatively low concentrations, they harm the biological processes of aquatic organisms. The molecules of dissolved detergents, by wedging themselves between water molecules, weaken the surface film. The hydrophilic part promotes the dissolution of the substance in water, while the hydrophobic part repels it. As a result, the entire water surface is covered with a peculiar film, which leads to the accumulation of toxic substances and a decrease in the oxygen concentration in the aquatic environment. To study the impact of surfactants on living organisms, we assess the ecological impact of synthetic surfactants on the biota of natural water bodies. We performed toxicological bioassays of aqueous solutions with low concentrations of sodium dodecylbenzenesulfonate on the crustacean Daphnia magna, which serves as a standard test organism both in Ukraine and abroad. The concentration of sodium dodecylbenzenesulfonate that caused the mortality of 50% of test organisms (LC₅₀) was determined, and the degree of toxicity of sodium dodecylbenzenesulfonate to aquatic ecosystems was found according to the EU Directive 93/67/EEC.

The present work focuses on the synthesis of Prosopis juliflora bark activated carbon supported on TiO₂ (PJBAC/TiO₂) composite through the sol-gel method for the decolourization of Direct Brown 2 (DB2). The prepared composite was characterized by Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) analysis. The surface area and pore diameter were explored by the Brunauer−Emmett−Teller method (N₂ adsorption/desorption). Furthermore, high-performance liquid chromatography (HPLC) and total organic carbon (TOC) analysis of the treated solution revealed a complete degradation of the dye molecule. The degradation efficiency of the prepared composite was analysed via batch equilibration studies. Maximum removal of DB2 (98%) was achieved at an initial concentration of 100 mg/L, contact time of 210 min, composite dose of 100 mg, and at pH 3. The well-known Freundlich and Langmuir isotherm equations were applied for the evaluation of equilibrium adsorption data. Lagergren and Ho−McKay kinetic models were employed to determine the adsorption rate constant. Additionally, the antimicrobial activity of PJBAC/TiO₂ was tested against Staphylococcus aureus, Escherichia coli, and Candida species. These results indicate that doping of TiO₂ on PJBAC inhibits the recombination of electron−hole pairs to improve photocatalytic performance in the visible region.

The shipbreaking area of Chattogram is one of the ecologically important regions in Bangladesh. To assess the possible ecological harm, sediment samples were collected and analyzed using the atomic absorption spectroscopy following standard methods from different locations of the shipbreaking yard at Chattogram. A decreasing trend in the amount of trace elements is present in sediment (average values): Pb (52.55 mg/kg) > Cr(VI) (45.97 mg/kg) > As (6.99 mg/kg) > Cd (0.218 mg/kg). The levels of harmful metals were higher than what was considered acceptable. According to the measured mean geo-accumulation index (I_geo), the research region was moderate to somewhat polluted, with the exception of Cd. The sediment samples were moderately to highly contaminated by Pb, Cr(VI), and As, according to the contamination factor (CF). Again, the pollution load indices (PLI) ranged from 1.91 to 3.10 (PLI > 1), indicating that the shipbreaking sites were moderately polluted with heavy metals and pose a risk to the ecosystem.

In this study, the kinetic transport of the simazine herbicide, which creates a serious threat to human health, was realized based on the diffusion via polymer inclusion membrane. In the polymer inclusion membrane synthesis, Aliquat 336 was used as a synthetic carrier and 2-nitrophenyl octyl ether was used as a plasticizer. The effect of the carrier concentration, the effect of the donor phase acid on the transport efficiency and the effect of the acceptor phase type change on the parameters of transport efficiency were studied. 62.56% of simazine was removed from donor phase at the end of 48 h in the optimum experimental conditions and permeability; flux values were calculated to be 3.056 × 10^–7 m/s and 1.515 × 10^–7 mol/m²s, respectively. As the last step, the surface characterizations of the polymer inclusion membranes were clarified using the method of field emission scanning electron microscopy. This study demonstrated economically and environmentally sustainable processes for the removal of micropollutants such as simazine.