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
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.
Electrocoagulation (EC) is an effective and emerging technique for the treatment of various types of wastewaters due to its unique adaptability, simple design, low cost, and environmental compatibility. This technique uses direct current between the metal electrodes immersed in the wastewater, which leads to the dissolution of electrode plates, releasing metal ions that destabilize and coagulate contaminants for subsequent removal. The performance of EC is influenced by various factors, including electrode material, pH, current density, temperature, and time. Despite its advantages, large-scale industrial application of EC requires further optimization of these key parameters and the development of reliable process models. This manuscript also reviews recent advancements in EC technology, such as EC-biological treatment, EC-chemical coagulation, photovoltaic-EC, and EC-membrane hybrid systems. Owing to its high pollutant removal efficiency, environmental sustainability, ease of operation, and relatively low automation cost, EC shows strong potential as a future wastewater treatment technology.
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
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
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.
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.
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.
This study examines the environmental risks associated with the transport and remobilization of heavy metals due to inter-basin water transfer, focusing on the Beni-Haroun to Timgad Dam project in Algeria. Sequential extraction and aqua regia digestion were utilized to evaluate the concentrations and speciation of iron, nickel, and lead in water and decanter sludge before and after water transfer. The results revealed substantial changes: iron levels increased significantly in sludge, rising from approximately 3559.95 mg/kg to a range of 40 765.33–67 262.26 mg/kg after transfer, primarily due to hydroxide precipitation under neutral to slightly alkaline pH conditions. Nickel concentrations in water rose sharply from 81 × 10–5 to 0.263 mg/L in the decanter water and from undetectable levels to 0.206 mg/L in the filtered water, which is attributed to redissolution mechanisms under altered pH conditions. Lead concentrations, while undetectable in the water samples, increased in sludge, peaking at 250 mg/kg, which was due to its precipitation as lead sulphate. These findings underscore the ecological risks posed by water transfer projects, emphasizing the need for sustainable strategies and rigorous monitoring to mitigate heavy metal remobilization impacts on water quality.
This research was carried out to determine the effectiveness of freeze-dried calcium alginate hydrogels in the form of beads for removing the azo dye, Eriochrome Black T (EBT), from an aqueous solution. After achieving standardization of the biosorbent preparation process, the influence of the following factors on dye sorption was analyzed: pH, dye concentration, and biosorbent dosage. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to characterize biosorbent material. In addition, the sorbent point of zero charge (PZC) was determined. The experimental data fitting level to the linearized forms of pseudo-first and -second order, intra-particle (IP) diffusion, and the Elovich adsorption models was analyzed, finding that they better fit a pseudo-second order model. The results showed that PZC confirmed that calcium alginate beads are a feasible material for EBT at pH 4 with 60
Microplastics (MPs) as a predominant pollutant is a huge trouble to the environment. MPs pose an immense challenge, with the ability to bioaccumulate and ultimately disturb human health, biodiversity, aquatic animals, etc. MPs comprising various toxic organic chemicals, antibiotics, and heavy metals have adverse environmental consequences. MPs in industrial wastewater must be treated with different methods depending on its characteristics. Conventional treatment systems have high operating costs, low biodegradability, and toxicity for industrial wastewater. Advanced techniques encompass various phase-changing processes, such as coagulation–flocculation, flotation, and membrane operations. Among membrane technologies, ultra- (UF), nano- (NF), and microfiltration (MF) are widely used, while dynamic membranes have recently gained attention due to their effectiveness in removing MPs. Additionally, hybrid membrane approaches, like advanced oxidation processes (AOPs), electrochemical processes, and adsorption techniques, can be combined to enhance MPs removal efficiency and mitigate membrane fouling. Some researchers emphasize the utilization of chemical or biological digestion and engineered methods like biodegradation and wet oxidation. This review paper primarily focuses on reactor design and the functionality of various membrane-based filters and bioreactors to develop practical, sustainable membrane technologies that address the challenging issue of MPs pollution in industrial wastewater. The primary objective is to outline the daunting problem of MPs pollution and explore key strategies for addressing it effectively.
Leachate treatment represents a challenge for landfill managers due to its high pollutant load and complex composition, which evolve in space and time. If not properly treated, landfill leachate threatens human health and the environment. Despite extensive laboratory-scale studies on treatment processes, economic assessments are less numerous in literature. To fill this gap, this study performs a techno-economic evaluation of a full-scale leachate treatment facility in Hamici landfill, Algeria. Leachate characteristics, treatment performance, and associated costs are analyzed from 2015 to 2023. The treatment chain comprises a membrane bioreactor (MBR) and nanofiltration. The plant has an influent capacity of 80 m3 day–1. In the evaluated period, the leachate flow rate ranged from 7400 to 13 300 m3 year–1, and the organic matter load varied between 7800 and 21 500 mg L–1 of chemical oxygen demand (COD). The MBR plant maintained a satisfactory removal efficiency >97
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
Microplastics (MPs) have been found in various ecosystems and have gained global attention as an emerging pollutant. In this study, 10 water samples were collected from 10 different ponds and analyzed to assess water quality, MP abundance, characteristics, pollution levels, and contamination risks. The investigation revealed that the dissolved oxygen (DO) in 90 NO_3^ - and PO_4^3 - . The heavy metal concentrations followed the trend: Cr > Cu > Fe > Mn > Ni > Zn > Pb > Cd, with Cr exhibiting higher values in all samples. These findings point to poorer water quality. Using the water quality index (WQI) and pollution indices, in particular, the heavy metal pollution index (MPI), heavy metal evaluation index (HEI), and degree of contamination (CD), 80
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
The main components of adaptive-compensatory processes in aquatic test organisms during the quality biotesting of an aquatic environment are considered. It is shown that adaptation is a set of physiological and biochemical responses in aquatic organisms that underlie the adaptation of an organism to changing environmental conditions and are aimed at maintaining relative constancy in its internal environment—homeostasis. It is emphasized that the study of adaptation processes provides an objective interpretation of biotesting results. The physiological meaning of the adaptation of aquatic organisms to external environmental impacts consists just in maintaining internal homeostasis and, accordingly, the viability of an organism in almost any conditions, to which it is able to respond adequately. Therefore, the functional systems of an organism work as self-regulated levels of the nervous and humoral systems, the action of which is aimed at achieving certain adaptive results beneficial for an organism. The leading role in this self-regulation belongs to the feedback processes, which were formed and fixed during the evolution of living beings as necessary for the survival of species. In other words, when the effect of physicochemical factors of an aquatic environment on the organism of hydrobionts occurs, compensatory and adaptive processes are launched in an organism to provide its survival in these conditions. This mechanism underlies the procedure of the quality biotesting of an aquatic environment.
A novel triazine-based dithiocarbamate (DTC) was synthesized using cyanuric chloride, ethylenediamine and carbon disulfide as raw materials. The DTC product was characterized by Fourier Transform infrared spectroscopy (FTIR) and elemental analysis, and its performance in removing lead ions from water through chelating-type adsorption was evaluated. Characterization results demonstrate the successful synthesis of the target product DTC. The lead ion removing ratio was shown to increase with pH value (2–6), removing time (0 to 160 min) and adsorbent dosage (0–4 g L–1), and then keep almost unchanged when further increasing their values. However, the removing ratio was found to decrease with the increase of initial lead ion concentration. Meanwhile, the removal quantity decreased with adsorbent dosage and increased with initial lead ion concentration. The DTC product achieved 97.2
An Erratum to this paper has been published: https://doi.org/10.3103/S1063455X26030100
For the first time at the national level, the article outlines and generalizes the key tasks of assessing the state of marine biocenoses and the quality of the marine environment through the implementation of an innovative ballast water management system, its testing at the Danube Institute of National University “Odesa Maritime Academy” (DINUOMA, Izmail, Ukraine), strictly adhering to the ballast water quality standard (BW) D2 of the Ballast Water Management Convention (BWMC, 2004) of the International Maritime Organization (IMO). The key object is represented by the overboard ballast water. Due to the presence of various living organisms in BW, there is a risk of their transfer between ecosystems, which may lead to the invasiveness of alien species and negative impacts on local ecosystems. Therefore, BW management is an important aspect of the ecological safety of maritime transport. The sequence of effective nodes of the current system has been established, considering the efficiency of their operation in accordance with legislative guidance on BW disinfection and treatment. In close cooperation with Turkish colleagues, experimental confirmation was obtained, involving modern ecological laboratories, of the demonstrative level of maximum neutralization of invasive alien organisms in the studied BW. On the Ukrainian side, at DINUOMA, initial successful trials of disinfection/treatment of fresh water from the Danube River, BW of the Marmara, Mediterranean, and Black seas, and waters of the Danube lakes were conducted, showing positive results. Experimentally confirmed was the level of neutralization of bioinvasions by the Scientific and Technological Research Council of Turkey (TÜBITAK), which decreased 11-fold compared to untreated water in the BW of the Marmara and Mediterranean Seas. According to the indicator “total bacterial count in water (37°C),” a decrease from 424 to 47 CFU/cm3 was achieved through triple water treatment, considering only a time interval of 15–40 min; in particular, E. coli and enterococcus were not detected already at the first stage of 15-min water treatment using the specified methods of the identical experimental BW disinfection/treatment system, equipped at the laboratory base of the Faculty of Maritime, Istanbul Technical University (Tuzla, Istanbul). The principle of cooperation was achieved in terms of scaling the system for its implementation in a realistic installation form on a research vessel.
