Journal of Water Chemistry and Technology最新文献

The study investigates the effectiveness of the decentralized wastewater treatment system (DEWATS) in managing and treating domestic wastewater. In this study, the performance of DEWATS located at Wazir Bagh Peshawar, Pakistan was assessed through water quality parameters, namely biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), pH, and temperature. The DEWATS mainly comprises a settler, anaerobic baffled reactor (ABR), and anaerobic filter (AF). Wastewater samples were collected and tested according to American Public Health Association Guidelines (APHA) guidelines on a weekly basis from September 2023 to July 2024. A total of 80 samples of influent and effluent were collected during the aforementioned period. The efficacy of DEWATS was assessed through various statistical tests and efficiency equations. Shapley additive explanations (SHAP) technique was used to render the most important physiochemical parameter that can play a vital role in the treatment process. Both Mann−Whitney U test and t-test produced p-values (<0.05) for BOD, COD, and TSS, showing a statistically significant difference between influent and effluent levels. The average efficiency of DEWATS in removing BOD, COD, and TSS was 76, 83, and 68% respectively. For BOD and COD effluent, SHAP analysis rendered influent BOD and sample temperature respectively as the most important parameters that can enhance the treatment process. Effluent BOD, COD and TSS have been compared with the permissible limits of National Environmental Quality Standards (NEQS) standards which suggest that the effluent water from DEWATS can be used for gardening purposes. The results concluded that DEWATS is an efficient system that can be used to treat water and can be a good alternative treatment option for small communities, schools, and hospitals. The treated water can be used for gardening purposes to reduce stress on groundwater and pumping energy consumption.

Rajasthan, a state of India, is dealing with significant water quality issues due to its dry climate, scanty rainfall, and contamination from industrial, agricultural, and domestic wastes. Excess levels of physicochemical parameters contribute to groundwater contamination in Rajasthan. The study highlights the rainfall status of Rajasthan, chemical contaminants of water and its effect on human health, agriculture, wildlife and environment with seasonal and regional variations. The western and northern regions (average 291 mm annual rainfall) of Rajasthan experience much more serious water crises than southern, eastern, central regions (average 500–600 mm annual rainfall). Key issues of these five regions include elevated levels of fluoride, nitrates, total dissolved solids, electrical conductivity and heavy metals that often exceed the permissible limits set by the World Health Organization (WHO) and the Bureau of Indian Standards (BIS). The over-reliance on groundwater has led to its depletion, with grave implications on both human health and the environment. High fluoride levels have caused widespread cases of dental and skeletal fluorosis, while nitrate contamination is linked to methemoglobinemia, commonly known as “Blue Baby Syndrome.” During dry seasons, over exploitation of water for domestic and agricultural purposes led to reduced water level and increase pollution of surface and groundwater. Current water management strategies need to be re-evaluated in addressing these issues, particularly in mitigating industrial pollution and agricultural runoff. The review emphasizes the need for sustainable water management practices, including remote sensing technologies, improved water infrastructure, and stricter regulatory frameworks to safeguard public health and promote long-term water security in the state.

The development of efficient pressure-driven membrane systems for the purification of contaminated waters from mixtures of heavy metals (HMs) is still a relevant scientific challenge due to the increasing volumes of industrial and municipal wastewaters, the limited efficiency of conventional methods for their purification from complex contaminants, and the requirements of UN Sustainable Development Goals by 2030 to safe wastewater treatment. The efficiency of the baromembrane filtration of contaminated solutions is provided by the combination of high selectivity and separation productivity. The key parameters of these processes are the retention coefficient and volume flux (specific productivity), which depend on the transmembrane pressure, the composition of an initial solution, and the material, pore size, and fouling characteristics of a membrane. In this study, the specific productivity of ultrafiltration and nanofiltration polymeric membranes was investigated in the treatment of solutions obtained after the reagent leaching of wastewater sludges from municipal water treatment plants from ions of heavy metals (HM) (Cd²⁺, Cr⁶⁺, Cu²⁺, Ni²⁺, Pb²⁺, Zn²⁺) and their mixtures in long-term experiments. The regularities of stabilization in volume fluxes and membrane retention coefficients in the studied processes were established. It is shown that the combination of complexation (for polyethyleneimine as an example) with pressure-driven membrane processes (ultrafiltration and nanofiltration) ensures the effective purification of wastewater sludges from the Bortnychi Aeration Station from HM (Cd, Cr, Cu, Ni, Pb, Zn) mixtures to the levels below the maximum permissible concentrations for all studied metals. The obtained data may be a basis for selecting optimal baromembrane systems for the treatment of real industrial wastewaters.

High efficiency and key parameters have been established for an integrated water treatment (ion exchange/microfiltration) process for the removal of F^– ions by using a finely disperse fraction (≤0.063 mm) of fluoride-selective resin Hydrolite ZG F 860 and a tubular microfiltration ceramic membrane created from clay materials by the Dumansky Institute of Colloid Chemistry and Water Chemistry of the National Academy of Sciences of Ukraine. It has been shown that the application of this process enables water defluoridation to the maximum permissible concentration (MPC) of F^– ions in potable water at their initial concentration from 1.7 to 2.9 mg/dm³ (pH, 7.4–7.7; operating pressure, 0.75 MPa; process duration, up to 8 h) by adding 2–4 g/dm³ of fluoride-selective resin to the solution. To achieve permissible F^– concentrations in potable water during its defluoridation under similar conditions at an initial F^– concentration of 3.0–3.55 mg/dm³, it is necessary to add 5–10 g/dm³ of this resin to the solution to be treated. The obtained results can be explained by that F^– ions are binded by the active aluminum groups present on the resin surface into stable complex aluminum fluoride compounds to remove F^– ions and reduce their concentration in the water with the further retention of the ion-exchange resin by the ceramic membrane in the form of a finely disperse fraction. At the same time, the volumetric flux of the ceramic membrane continuously decreases from 0.44 to 0.04 m³/(m² h) due to the significant clogging of pores by the fine resin fraction. The combination of microfiltration and ion exchange is a promising approach to the efficient defluoridation of natural waters due to that, during water treatment, not only the spent ion-exchange resin, but also mechanical impurities, fine suspended solids, colloidal and organic compounds, and microbiological contaminants are removed from them.

Silica is dissolved from sands, rocks and minerals by water flowing through or over the Earth, which is one of the pollutants water gathers. Although there are no known health risks associated with drinking water silica exposure, silica in water plays crucial role and can pose serious issues for industries, particularly in boiler and steam application systems. However, removing silica from water has always been a huge challenge due to its polymeric and colloidal state. There have been many technologies proposed for removing silica from water; however, as remediation methods change daily, it is important to find strategies that work well at a reasonable cost. This study, which must be essential for students, engineers, businesspeople, scientists, and policy makers, has a primary focus on removal solutions of silica from water and has chronologically examined the causes of silica contamination, various forms of silica, characterization of silica, the effects of various types of silica in water.

Groundwater quality is rapidly deteriorating due to increased industrial and anthropogenic activities, and the water is becoming unfit for drinking and irrigation. Pakistan, a developing country, is largely affected by the high concentration of pollutants present in groundwater. The present study was performed to investigate the effect of groundwater quality in Bahawalpur on drinking water supply and irrigation. The data revealed that water quality parameters were not consistent with the drinking water quality indicators recommended by the World Health Organization, due to anthropogenic activities, explosive population growth, and the seepage of toxic compounds into groundwater aquifers. Among the physical parameters, pH was in the range of 7.24–8.01, electrical conductivity 473–4566 µS cm^–1, total dissolved solids 280–2288 mg L^–1 and hardness of water 150–780 mg L^–1, respectively. The concentrations of cationic and anionic compounds were relatively within permissible limits in Chak 10/BC, 12/BC, Dera Bakha, Fathuwali, and Goth Lal. Sodium adsorption ratio (SAR) and residual sodium carbonate (RSC) values were also within the safe limits except in Muhajir colony and Islamia colony, where higher RSC makes the water unsuitable for irrigation. Water samples collected at selected locations also exhibited higher concentrations of arsenic and cadmium than permissible limits. The heavy metal pollution index indicates that arsenic and cadmium concentrations exceed their threshold levels, posing a threat to humans. Similarly, the colony forming unit counts for E. coli and total coliforms were 74 and 84 CFU, respectively. The water quality index values indicate poor groundwater quality for human consumption. Therefore, strict regular monitoring of the physicochemical properties of groundwater is required to improve public health.

The groundwaters of unprotected aquifers are influenced by both natural and anthropogenic pollutants, among which compounds of heavy metal ions, ammonium nitrogen, humic complexes, and phenols are predominant. Traditional technologies (aeration/filtration, coagulation/settling/filtration) can not provide efficient purification from them. The use of strong oxidizers (O₃, H₂O₂, KMnO₄, NOCl, Cl₂) as reagents increases the cost of technology and complicates operation. One of the ways to solve this problem is to use the method of hydrodynamic cavitation (HDC). The objective of this study was to investigate the effect of hydrodynamic cavitation on the oxidation kinetics of ammonium nitrogen, humic complexes, and phenols and to develop the mechanisms for the destruction and removal of these substances from aqueous solutions. The medium to be studied was a simulant prepared on the basis of tap water with the addition of a concentrated solution containing a balanced potassium–nitrogen–phosphorus fertilizer, which imparted the water with color and contamination with dissolved humic complexes (up to 3.0 mg/dm³) and ammonium nitrogen (up to 1.5 mg/dm³). Phenol (CAS no. 108-95-2) was used to simulate water contamination with phenols (up to 1.0 mg/dm³). As a result of performed studies, it has been established that the dissolved oxygen (DO) concentration in the treated water grows (up to 3 mg/dm³), when hydrodynamic cavitation (hereinafter, HDC) is applied (without air access), and the combination of HDC with coagulation makes it possible to remove all the aforesaid concentrations of contaminants. Complex organic complexes were subject to destruction−conversion to colloids with destabilization by an electrolyte solution. Ammonium nitrogen was extracted by conversion into gaseous N₂. Based on the results of comparative single- and multistage HDC studies, it has established that the use of multistage HDC increases the efficiency of treatment to 21% at the same consumption of electric power. Using the contemporary cavitation theory, some mechanisms for the destruction and oxidation of humic complexes, ammonium nitrogen, and phenols were proposed.

In the present study, the effects of the combination of electrooxidation (EOx) and ozone (O₃) processes on chemical oxygen demand (COD) removal and associated color removal and energy efficiency in the treatment of biologically treated vinasse are investigated. The results showed that hybrid technology is more effective than EOx and ozonation alone. The influence of operating parameters such as initial pH (5.0–9.0), operating time, current density (10.4–83.3 A/m²) and O₃ feed rate (2–5 mg/L) on percentage of color and COD removal as well as specific energy consumption and operating cost in the treatment of biologically treated wastewater was investigated. The COD removal percentage increased from 58.6 to 100% with an increase in current density from 10.4 to 83.3 A/m² when using a Nb boron-doped diamond-based electrode (Nb/BDD) after 4 h of operation. While complete color removal is observed after 4 h with the electrooxidation process alone, almost complete color removal is achieved in less than 3 h with the hybrid technique. The specific energy consumption and operating cost for the ozone-integrated electrooxidation process under optimal conditions were calculated to be 25.8 kW h/kg COD removed and $9.07/m³ respectively. Taking as a basis the operating costs of ozone-integrated electrooxidation, a slight raise of approximately 8% in the treatment costs were calculated with the electrooxidation alone process.

In this study, polyethylene glycol-stabilized nanoscale zero-valent iron (PEG-nFe⁰) was loaded on sludge biochar (SBC) via a liquid-phase reduction method for the removal of Cd(II) from aqueous solutions, where nFe⁰ is the Fe⁰-FeO/FeOOH mixture. The morphology, functional groups, and crystal structure of the resulting PEG-nFe⁰@SBC composites were characterized using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) techniques. The incorporation of PEG introduced numerous –OH functional groups, which facilitated the dispersion of nFe⁰ as smaller particle size on the SBC surface. Kinetic studies revealed that the Cd(II) removal process by PEG-nFe⁰@SBC adhered to a pseudo-second-order kinetic model. The Freundlich isotherm model provided the best fit for describing the adsorption process. Thermodynamic analysis indicated that the removal of Cd(II) by PEG-nFe⁰@SBC was a spontaneous endothermic reaction. Under the initial conditions of 200 mg/L Cd(II), 1 g/L of PEG-nFe⁰@SBC, pH 5.0, and a temperature of 298 K, more than 85.8% of Cd(II) was removed within 24 h. The presence of PEG significantly enhanced the oxidation resistance of nFe⁰ in air. The adsorption capacity of PEG-nFe⁰@SBC for Cd(II) remained stable at 123.60 mg/g even after 90 days of air exposure, compared to 73.87 mg/g for nFe⁰@SBC. Typical macroscopic composition of natural water (Ca(II), Mg(II), humic acid (HA)) had minimal impact on Cd(II) removal by PEG-nFe⁰@SBC. Mechanistic analysis suggested that the primary removal mechanisms for Cd(II) by PEG-nFe⁰@SBC involved precipitation/co-precipitation and complex formation.

The objective of this study was to investigate the uptake of Cr(VI) from aqueous solutions using amino-functionalized carbonaceous materials synthesized through hydrothermal carbonization of Camellia oleifera shells in the presence of ammonia solution. The characterization of the carbonaceous materials was performed employing various techniques, including Fourier-transform infrared spectroscopy (FTIR), N₂ adsorption–desorption analysis, elemental analysis and scanning electron microscopy (SEM). The adsorption capacity and kinetics of the prepared carbon-based materials for Cr(VI) in wastewater were investigated. The results showed as follows: adsorption kinetics can be elucidated by pseudo-second-order model, and the adsorption isotherm can be fitted by Langmuir equation. The maximum adsorption capacity for Cr(VI) by the amino-functionalized carbonaceous materials reached 483.52 mg g⁻¹, which was approximately four times greater than that of unmodified carbonaceous materials (123.01 mg g⁻¹). Furthermore, the as-prepared carbonaceous materials demonstrated an impressive ability to remove 99.71% of Cr(VI) ions from actual wastewater generated by the electroplating industry, thereby meeting the discharge standards established by regulatory authorities. These findings indicate that amino-functionalized carbonaceous materials hold significant potential as cost-effective adsorbents for the removal of Cr(VI) ions from aqueous solutions.