Pollutant Removal Efficiency Research Articles

Refractory organic matter removal from mature leachate by bipolar electrocoagulation-electrooxidation reactor configurations

In this study, mature leachate treatment with combined electrochemical processes was investigated to benefit from the advantages of electrocoagulation (EC) and electrooxidation (EO) simultaneously. First, control experiments were conducted, the most effective anode-cathode combination for EO was selected as Ti/IrO2-Gr, the number of Al electrodes for EC was determined as 3 and the number of Fe electrodes was determined as 5. Optimization of process parameters of the combined system with Al and Fe electrodes was conducted with Box-Behnken design (BBD). With BBD, the effect of the process parameters (initial pH, current density, and reaction time) on the system responses (COD, UV254, and color removal efficiencies) was determined. The suitability of the created model in the study was analyzed statistically and the results of quadratic models were found compatible with experimental studies. The model's capacity for prediction was also confirmed by validation experiments under optimum conditions. By implementing the optimum conditions, COD, UV254, and color removal efficiencies were determined as 71.5 %, 60.2 %, and 93.2 %, respectively for the combined process with Al electrodes and 79.5 %, 68.0 %, and 97.7 %, respectively for the combined process with Fe electrodes. Correlation of actual and predicted data showed that BBD is reliable for optimizing process parameters of combined processes with Al and Fe electrodes. The obtained results showed that combined processes are more effective than hybrid processes, based on both pollutant removal efficiencies and energy consumption.

Multidimensional assessment of a Nature-based Solution for decentralized greywater treatment in Costa Rica

In Costa Rica, water supply networks provide water to over 94% of the country's population. However, only an estimated 14% of wastewater receives proper treatment. The lack of centralized sanitation infrastructure has resulted in the use of septic tanks and the discharge of untreated greywater into rivers, causing environmental degradation of surface waters. Retrofitting conventional centralized sewer networks and treatment plants into the existing urbanization presents extensive social, economic, and technical challenges. Nature-based Solutions (NbS) for greywater treatment can reduce pollutant loads and improve the environmental status of water resources and represent an opportunity for technical leapfrogging towards sustainable, decentralized on-site treatment and reuse. However, the implementation of NbS in urban areas poses significant challenges due to the complex interplay of social, regulatory, and economic factors. Specifically, for on-site greywater treatment systems, meeting several criteria, including efficient pollutant removal, affordability, and public acceptance is essential for successful implementation and operation. This study assesses the technical, socio-economic, and political-regulatory dimensions relevant to implementing NbS for decentralized greywater treatment. To conduct this research, a Real-World Lab was established in the Great Metropolitan Area of Costa Rica, employing a transdisciplinary approach. This approach provided a physical space and societal context to integrate site-specific aspects and understand the various factors that influence the implementation and upscaling of NbS. As part of our methodology, we analyzed the water quality parameters and treatment performance of a NbS prototype for decentralized greywater treatment. Within the Real-World Lab framework, we conducted interviews, surveys, and field observations to investigate socio-economic and political-regulatory aspects. Our results highlight the technical potential of the NbS prototype. However, the limitation lies in the governance scheme and financing mechanisms required for upscaling the NbS as a decentralized on-site technology across the country. Our multidimensional assessment provides insights into the requirements for widespread implementation of NbS, applicable to other regions facing similar retrofitting sanitation challenges.

Visible Light-Triggered Chitosan Supported Ternary Ferrite for Efficient Removal of Organic Dye Pollutants from Wastewater

Visible Light-Triggered Chitosan Supported Ternary Ferrite for Efficient Removal of Organic Dye Pollutants from Wastewater

Influence of ZrO2 nanoparticles on the structural and photocatalytic properties of three-dimensional PVA/g-C3N4 polymer films

This study introduces a novel polymer nanocomposite film of polyvinyl alcohol (PVA), carbon nitride (g-C3N4), and zirconia (ZrO2), created via solution casting for effective water remediation of organic dyes. The film shows significant potential for enhancing pollutant removal efficiency and offering a sustainable solution for water reuse. Comprehensive characterization using FTIR, XRD, UV–vis, TGA, and FESEM-EDX indicated strong interfacial interactions among PVA, ZrO2, and g-C3N4. XPS and UV–vis spectroscopy revealed a reduction in the optical energy gap from 4.8 to 3.95 eV, enhancing photocatalytic activity. SEM confirmed uniform dispersion of ZrO2 and g-C3N4 within the PVA matrix. Kinetic studies of methylene blue (MB) degradation under solar irradiation at neutral pH showed rate constants (k) of 0.0032 min−1, 0.0094 min−1, 0.0383 min−1, and 0.0816 min−1 for PVA, PVA/(0.003)ZrO2/g-C3N4, PVA/(0.007)ZrO2/g-C3N4, and PVA/(0.01)ZrO2/g-C3N4, respectively. The corresponding half-life times (t1/2) were 216.6 min, 73.7 min, 18.1 min, and 8.5 min, with photodegradation efficiencies of 10 %, 75.2 %, 90 %, and 95 %. This recyclable nanocomposite polymer, PVA/ZrO2/g-C3N4, shows promise for effective decontamination of organic pollutants in water, presenting an innovative approach for advanced remediation and secure wastewater recycling.This work is crucial for society as it contributes to solving the global challenge of water pollution, ensuring access to clean and safe water.

Titanium Carbide (Ti3C2Tx) MXene for Sequestration of Aquatic Pollutants.

The rapid expansion of industrialization has resulted in the release of multiple ecological contaminants in gaseous, liquid, and solid forms, which pose significant environmental risks to many different ecosystems. The efficient and cost-effective removal of these environmental pollutants has attracted global attention. This growing concern has prompted the synthesis and optimization of nanomaterials and their application as potential pollutant removal. In this context, MXene is considered an outstanding photocatalytic candidate due to its unique physicochemical and mechanical properties, which include high specific surface area, physiological compatibility, and robust electrodynamics. This review highlights recent advances in shaping titanium carbide (Ti3C2Tx) MXenes, emphasizing the importance of termination groups to boost photoactivity and product selectivity, with a primary focus on engineering aspects. First, a broad overview of Ti3C2Tx MXene is provided, delving into its catalytic properties and the formation of surface termination groups to establish a comprehensive understanding of its fundamental catalytic structure. Subsequently, the effects of engineering the morphology of Ti3C2Tx MXene into different structures, such as two-dimensional (2D) accordion-like forms, monolayers, hierarchies, quantum dots, and nanotubes. Finally, a concise overview of the removal of different environmental pollutants is presented, and the forthcoming challenges, along with their prospective outlooks, are delineated.

Mechanical Enhancement and Water Treatment Efficiency of Nanocomposite PES Membranes: A Study on Akçay Dam Water Filtration Application.

Polymeric membranes are widely used in water treatment because of their ease of fabrication and low cost. The flux and purification performance of membranes can be significantly improved by incorporating appropriate amounts of nanomaterials into the polymeric membrane matrices. In this study, neat poly(ether sulfone) (PES), PES/nano copper oxide (CuO), and PES/nano zinc oxide (ZnO) membranes are fabricated via phase inversion. The pure water flux of the neat PES membrane, which is 355.14 L/m2·h, is increased significantly with the addition of nano-CuO and nano-ZnO, and the pure water fluxes of the nanocomposite membranes vary in the range of 392.65-429.74 L/m2·h. Moreover, nano CuO and nano ZnO-doped PES nanocomposite membranes exhibit higher conductivity, color, total organic carbon, boron, iron, selenium, barium, and total chromium removal efficiencies than neat PES membranes. The membrane surfaces examined by Scanning Electron Microscopy (SEM) after water filtration revealed that those containing 0.5% wt. nano CuO and nano ZnO are more resistant to fouling than the membrane surfaces containing 1% wt. nano CuO and nano ZnO. Based on the results of this study, 0.5% wt. nano ZnO-doped PES membrane is found to be the most suitable membrane for use in water treatment due to its high pure water flux (427.14 L/m2·h), high pollutant removal efficiency, and high fouling resistance. When the mechanical properties of the membranes are examined, the addition of CuO and ZnO nanoparticles increases the membrane stiffness and modulus of elasticity. The addition of 0.5% and 1% for CuO leads to an increase in the modulus of elasticity by 57.95% and 324.43%, respectively, while the addition of 0.5% and 1% for ZnO leads to an increase in the modulus of elasticity by 480.68% and 1802.43%, respectively. At the same time, the tensile strength of the membranes also increases with the addition of nanomaterials.

Separation and recovery of elements from drainage water arising in soilless tomato cultivation − Application of electrocoagulation

Soilless tomato cultivation requires significant water and nutrient inputs, resulting in the generation of drainage water (DW) with varying macro- and micronutrient compositions. This poses challenges for effective nutrient’s reuse due to technological and economic constraints. This study investigates the feasibility of using electrocoagulation, employing aluminum electrodes, to treat DW. The experiment involved three different current densities (2 A/m2, 4 A/m2, and 8 A/m2) and a 24-hour hydraulic retention time (comprising 4 h of electrocoagulation followed by 20 h of stirring). Treatment performance, kinetics, sludge characteristics, and energy consumption were evaluated. The elemental composition of the electrocoagulation-treated DW, including P, N, S, Cl, Ca, Mg, K, Na, Mo, Mn, Fe, Zn, Cu, B, organic compounds, and Al, was analyzed. The results showed that higher current densities resulted in increased pollutant removal rates and efficiencies. Importantly, the electrocoagulation process facilitated phosphorus recovery at pH < 7.0, ranging from 95.3 ± 0.6 % (at 2 A/m2) to 99.9 ± 0.1 % (at 8 A/m2), with corresponding energy consumption between 6.03 kWh/kgP and 29.98 kWh/kgP. Electrocoagulation as a drainage water treatment not only offers phosphorus recovery, but can also recovery B, and – to a certain extent – S, Mg, K, Mn, Zn and Cu. Other elements, such as Na and Cl, remained at stable levels. This allows for the separation of valuable elements (P) from those that interfere with cultivation (Na, Cl). This research could contribute to the development of a precise treatment process to address nutrient and pollutant management challenges in agricultural wastewater.

Nitrate and ammonium removal in constructed wetlands: Experimental insights and zero-dimensional numerical modeling

Constructed wetlands (CWs) have emerged as effective wastewater treatment systems, mimicked natural wetland processes but engineered for enhanced pollutant removal efficiency. Ammonium (NH4+) and nitrate (NO3−) are among common pollutants in wastewater, posing significant environmental and health risks. The primary objective of this study is to compares the performance of CWs using gravel and three sizes of natural pumice, along with phragmites australis, in horizontal and horizontal-vertical CWs for nitrate and ammonium removal in the complementary treatment of domestic wastewater. Additionally, the study aims to develop and validate a numerical model using MATLAB software to predict the removal efficiency of these pollutants, thereby contributing to the optimization of CW design and operation. The model operates as a zero-dimensional model based on the law of mass conservation, treating the wetland as a completely mixed reactor, thus avoiding complexities associated with solute movement in porous media. It accurately could predict removal efficiency of chemical, biochemical, and biological indicators while considering active and passive absorption mechanisms by plant uptake. Notably, the determination of coefficients in the model equation does not rely on potentially error-prone laboratory measurements due to sampling issues. Instead, optimization techniques alongside field data robustly estimate these coefficients, ensuring reliability and practicality. Results indicate that higher pollutant concentrations increase reaction rates, particularly enhancing CW efficiency in ammonium removal. Pumice, especially in larger sizes, exhibits superior absorption due to increased porosity and surface area. Overall, the model accurately predicts nitrates concentrations, demonstrating its potential for CW performance optimization and confirming the significance of effective pollutant removal strategies in wastewater treatment.

Novel insights into the biological state in algal-bacterial granular sludge granulation: Armor-like protection provided by the algal barrier

Algal-bacterial granular sludge (ABGS) composed of microalgae and aerobic granular sludge, is a sustainable and promising technology for wastewater treatment. However, the formation mechanism of ABGS has not been clearly defined, and the direct formation of ABGS in saline wastewater has rarely been investigated. This study proposed novel insights into the granulation process of ABGS by assembling the algal barrier, which was successfully cultivated directly in saline wastewater. The results concluded that ABGS with the algal barrier maintained a higher biomass (MLSS of 7046 ± 61 mg/L), larger particle sizes (1.21 ± 0.06 mm), and better settleability (SVI30 of 46 ± 1 mL/g), enabling efficient pollutants removal. Soluble microbial products (SMP) were found to be closely related to the emergence of the algal barrier. In addition, under salinity stress, the high production of extracellular polymeric substances (EPS, 133.70 ± 1.40 mg/g VSS), specifically TB-EPS (90.29 ± 1.12 mg/g VSS), maintained a crucial role in the formation of ABGS. Further analysis indicated that biofilm producing bacteria Pseudofulvimonas and filamentous eukaryote Streptophyta were the key players in ABGS formation with the algal barrier. Furthermore, the enhancement of key genes and enzymes involved in nitrogen metabolism, TCA cycle, and polysaccharide metabolism suggested a more robust protective effect provided by the algal barrier. This study is expected to advance the application of simultaneous ABGS formation and pollutant removal in wastewater.

Effective remediation of agricultural drainage at three influent strengths by bioaugmented constructed wetlands filled with mixture of iron‑carbon and organic solid substrates: Performance and mechanisms

Agricultural drainage containing a large quantity of nutrients can cause quality deterioration and algal blooming of receiving water bodies, thus needs to be effectively remediated. In this study, iron‑carbon (FeC) composite-filled constructed wetlands (Fe-C-CWs) were employed to treat farmland drainage at three pollution levels, and organic solid substrates (walnut shells) and phosphate-accumulating denitrifying bacteria (Pseudomonas sp. DWP1) were supplemented to enhance the treatment performance. The results showed that the Fe-C-CWs exhibited notably superior removal efficiency for total nitrogen (TN, 52.0–58.2 %), total phosphorus (TP, 67.8–70.2 %) and chemical oxygen demand (COD, 56.7–70.4 %) than the control systems filled solely with gravel (28.5–32.5 % for TN, 33.2–40.5 % for TP and 30.2–55.0 % for COD) at all influent strengths, through driving autotrophic denitrification, Fe-based dephosphorization, and organic degradation processes. The addition of organic substrates and functional bacteria markedly enhanced pollutant removal in the Fe-C-CWs. Furthermore, use of FeC and organic substrates and denitrifier inoculation decreased CO2 and CH4 emissions from the CWs, and reduced global warming potential of the CWs at low influent strength. Pollutant removal efficiencies in the CWs were only marginally impacted by the increasing influent loads except for NO3−-N, and pollutant removal mass was largely increased with the increase of influent strengths. The microbial community in the FeC composite-filled CWs exhibited distinct distribution patterns compared to the gravel-filled CWs regardless of the influent strengths, with obviously higher proportions of dominant genera Trichococcus, Geobacter and Ferritrophicum. Keystone taxa associated with pollutant removal in the Fe-C-filled CWs were identified to be Pseudomonas, Geobacter, Ferritrophicum, Denitratisoma and Sediminibacterium. The developed augmented Fe-C-filled CWs show great promises for remediating agricultural drainage with varied pollutant loads.

Synthesis of nano calcium silicates from waste calcite and aragonite phases for efficient adsorptive removal of industrial organic pollutants

The present study focuses on the adsorption efficacy of solid-state synthesized calcium silicate for removing congo red dye. Three different sources were used as calcium precursors; one was calcium carbonate, and the other two were natural waste sources, aragonite (P. globosa) and calcite (Eggshells). Structural analysis and functional groups of the samples were carried out by X-ray diffractometer (XRD), and a Fourier Transform Infrared Spectrometer (FTIR). Various well-known models/equations models such as the Liner Straight Line method of Scherrer’s equation (LSLMSE), Sahadat-Scherrer Model (SSM), Monshi-Scherrer model (MSM), Williamson-Hall model (WHM), Size-Strain plot method (SSP), and Halder-Wagner Model (HWM) were applied to compute the crystallite size of the synthesized calcium silicates; the estimated crystallite size range was 8–77 nm. The adsorption efficacy of the synthesized E-CaSiO3, S-CaSiO3, and C-CaSiO3 was assessed under various provisos for eradicating Congo red dye from wastewater. Computed results revealed that the dye removal percentages were approximately 100 % at 120 min and 200 rpm for 0.2 g E-CaSiO3. The point of zero charge evaluation showed that the pH of the adsorbents during maximum dye removal was 7 and was less than the value of pHpzc. Thermodynamics studies confirmed that the adsorption process was spontaneous. The method of adsorption of dye by the adsorbent was more clearly comprehended by Langmuir, Freundlich, and Temkin adsorption isotherm. 151.28 mg/g was the maximum adsorption capacity for S- CaSiO3 depending on the Langmuir isotherm model’s linear form (R2 = 0.924).

The role of microalgae in effective instream agricultural wastewater treatment

ABSTRACT The Egyptian water crisis has encouraged the exploration of innovative solutions for wastewater treatment. One promising approach is using treated agricultural drainage water for its large amount per year and low pollution. There are many methods used for the treatment of wastewater, but this research focused on a new one which is the use of microalgae for in-situ treatment of wastewater, due to its ability to uptake and adsorb pollutants, aerate water, and produce biomass for potential use as a biofuel or fertilizer. Microalgae have shown great potential for removing various pollutants from wastewater, including organic matter, nutrients, heavy metals, and pathogens. Moreover, the use of microalgae for wastewater treatment can be more cost-effective and sustainable than traditional wastewater treatment methods, which often require large and expensive infrastructure. This study aimed to investigate the effectiveness of using microalgae for in-situ treatment of agricultural drainage wastewater of Bahr El-Baqar drain. The results revealed that the removal efficiencies were 29% for BOD (biochemical oxygen demand), 46.9% for COD (chemical oxygen demand), 56.1% for TSS (total suspended solids), 31% for HM (Heavy Metal) removal, and 86% increment in DO (Dissolved Oxygen) concentration. This experiment provided evidence that microalgae could be a promising and cost-effective solution for in-situ treatment of agricultural drainage wastewater, with high removal efficiencies for pollutants in wastewater and the potential to reduce the need for constructing large and expensive wastewater treatment plants.

Unveiling the earthworm-associated preferential remediation of emerging organic pollutants and heavy metals in MSW-based vermicomposting systems: Insights through the lens of multivariate techniques and novel empirical models

Studies on the efficacies of vermicomposting and composting in countering the toxic impacts of pollutant cocktails in municipal solid waste (MSW) are scarce. Moreover, further research is needed to explore earthworms' remediation preferences for various pollutants in heterogeneous vermicomposting feedstocks, such as MSW. Therefore, removal dynamics of pesticides (chlorpyrifos, cypermethrin, and carbofuran), pharmaceuticals (diclofenac and carbamazepine), and heavy metals (Pb, Zn, Cu, and Mn) in MSW-based vermicomposting (Eisenia fetida and Eudrilus eugeniae) and composting systems were evaluated through multivariate analytical techniques (principal component (PCA) and multi-factor (MFA)) on the R-platform. Both earthworms satisfactorily increased their population and augmented NPK (nitrogen, phosphorous, and potassium) availability, cation exchange, microbial biomass C&N, and their metabolic activity 2–3 folds more than composting, accompanied by a 3–4 folds reduction of organic C, pH, and bulk density. Correspondingly, heavy metals, pesticides, and pharmaceuticals decreased by 8-10-folds via earthworm's significant pollutant removal efficiencies that subsided MSW-driven ecological risks by 60–90%. PCA and MFA revealed that N, P, and K-availability, organic C, and microbial activity were the indicative attributes for heavy metal and emerging organic micropollutant (EOMP)-removal during biocomposting; however, earthworms remove pesticides faster than pharmaceuticals and heavy metals. PCA-based novel empirical models demonstrated that in MSW-only feedstock, earthworm-mediated pollutant detoxification followed the order of pesticides > pharmaceuticals > heavy metals. However, in MSW combined with cow dung (1:1 ratio) feedstock, the detoxification order shifted to pharmaceuticals > heavy metals > pesticides. Therefore, this study provides fresh insights into pollutant-focused feedstock optimization for vermicomposting through model-based approaches, advancing the eco-friendly valorization of toxic MSW.

Microalgae-mediated bioremediation: current trends and opportunities-a review.

Environmental pollution poses a critical global challenge, and traditional wastewater treatment methods often prove inadequate in addressing the complexity and scale of this issue. On the other hand, microalgae exhibit diverse metabolic capabilities that enable them to remediate a wide range of pollutants, including heavy metals, organic contaminants, and excess nutrients. By leveraging the unique metabolic pathways of microalgae, innovative strategies can be developed to effectively remediate polluted environments. Therefore, this review paper highlights the potential of microalgae-mediated bioremediation as a sustainable and cost-effective alternative to conventional methods. It also highlights the advantages of utilizing microalgae and algae-bacteria co-cultures for large-scale bioremediation applications, demonstrating impressive biomass production rates and enhanced pollutant removal efficiency. The promising potential of microalgae-mediated bioremediation is emphasized, presenting a viable and innovative alternative to traditional treatment methods in addressing the global challenge of environmental pollution. This review identifies the opportunities and challenges for microalgae-based technology and proposed suggestions for future studies to tackle challenges. The findings of this review advance our understanding of the potential of microalgae-based technology wastewater treatment.

Optimizing photocatalytic performance in an electrostatic-photocatalytic air purification system through integration of triboelectric nanogenerator and Tesla valve

Increasing the collision frequency between gas molecules and photocatalysts can enhance the removal efficiency of volatile organic compounds (VOCs) and particulate matter (PM) in air. In this study, we propose an Electrostatic-Photocatalytic air purification system, containing Tesla valve, triboelectric nanogenerator (TENG), and photocatalysis parts. The incorporation of Ag@ZnO nanorod array (Ag@ZnO-NR) photocatalysts into the internal baffles of the Tesla valve pipeline effectively enhances the collision probability between air pollutant molecules and photocatalysts, and thus facilitating the removal efficiency of pollutants. Additionally, the high-voltage electricity (∼9.0 kV) generated by the TENG facilitates the separation of electron-hole pairs in the photocatalyst, leading to increased production of superoxide radicals (O•−2), hydroxyl radicals (•OH), and holes (h+), thereby enhancing the photocatalytic efficiency. In a 1.8 L space system, we achieved an approximately 97 % removal efficiency for toluene within 130 minutes and a similar efficiency for formaldehyde (∼200 ppm) within 175 minutes. Additionally, the PM2.5 concentration rapidly decreased from 999 μg·m−3 to 42 μg·m−3 within 6 minutes, alongside with a significantly faster pollutant removal rate compared to conventional methods. By integrating Tesla valves, TENG, and photocatalysis, this combined system presents an efficient and promising approach for addressing indoor air pollution, with potential applications across various settings.

Effective inhibition of chloride ion interference in photocatalytic process by negatively charged molecularly imprinted photocatalyst: Behavior and mechanism

The ubiquitous chloride ions (Cl−) in water seriously interfere with pollutant oxidation and inevitably generate undesirable chlorinated byproducts. In this study, we report for the first time that a negatively charged molecularly imprinted photocatalyst (MIP) can effectively inhibit Cl− interference and suppress the production of chlorination byproducts (the yield of chloroacetic acid was only 16 % of the bare photocatalyst system) while ensuring efficient degradation of target pollutants, thereby greatly improving the safety of the pollutant degradation process. Taking antibiotics as target pollutant, we investigated the mechanism of action of MIP by comparing the antibiotic degradation pathways, fate of photogenerated active species and production of reactive chlorine species (RCS) in the MIP and bare photocatalyst system. The mechanism by which MIP inhibits Cl− interference was mainly based on a synergy between electrostatic repulsion and steric hindrance induced by the specific capture of antibiotics in imprinted cavity, which effectively suppressed the production of RCS and hindered the participation of RCS in antibiotics degradation. In addition, MIP showed good compatibility with common cations, anions and organic matter, and performed well within a broad pH range in various water environments. Thus, the negatively charged MIP provides a feasible approach for the safe and efficient removal of pollutants in Cl− containing water.

Adsorption‐Based Approaches for Exploring Nanoparticle Effectiveness in Wastewater Treatment

AbstractThe treatment of wastewater is essential to preserving the environment and public health. Recent advances in this field have made nanoparticles attractive tools due to their exceptional selectivity, reactivity, and surface area. Particularly, their use in adsorption‐based wastewater treatment has garnered significant interest, focusing on how well nanoparticles can adsorb chemical contaminants, thereby improving treatment effectiveness. A thorough analysis explores various aspects of nanoparticles in wastewater treatment, including different types of nanoparticles used for adsorption, underlying mechanisms, and numerous factors affecting their pollutant removal efficiency. However, it also recognizes potential negative environmental impacts, underscoring the need for comprehensive risk assessments, including eco‐toxicity, release dynamics, and long‐term ecological effects. In light of these challenges, the review emphasizes the revolutionary potential of new nanoparticles in transforming wastewater treatment paradigms. Examples include ZnO nanoparticles and Fe₃O₄ magnetic nanoparticles (MNPs), which excel at removing dyes and reducing sludge volume, while CuO and TiO₂ nanoparticles rapidly eliminate organic pollutants and heavy metals like Pb2+. Additionally, graphical illustrations highlight nanoparticles′ advantages, especially in removing cadmium. These findings underscore the future direction of research on wastewater treatment using nanoparticles, pointing toward increased sustainability and efficiency in addressing water pollution issues.

Interlayer-confined strategy to modulate alkaline reaction microenvironment for in-situ degradation of ofloxacin

In advanced oxidation processes designed for the mineralization of organic contaminants, the acidic microenvironment in the peroxymonosulfate (PMS) activation system poses a major threat to the stability of active species. In this study, we developed a low-cost Co-Mg–layered double hydroxide (LDH) structure with an OH−-enriched, interlayer-confined alkaline microenvironment around Co sites. This structure exhibited enhanced surface availability and a short reactant diffusion path, which accelerated proton migration and regulated local pH at the slipping plane. Theoretical calculations revealed that CoMg-LDH exhibited high catalytic activity for PMS cleavage and generated high-valence Co-oxo (Co(IV)=O) species in this specific microenvironment. At a natural pH, the optimized system achieved 100 % removal efficiency of the target pollutant (ofloxacin), with negligible Co leaching. It also demonstrated stability in long-term experiments and effectively purified hospital wastewater. Overall, this study provides valuable insights into the in-situ degradation of contaminants through self-regulating catalytic systems.

Fabrication of dopamine/TiO2 nanocomposite hydrogel using fenugreek gum for efficient photocatalytic degradation of organic pollutants under visible light irradiation

The efficient removal of organic pollutants from wastewater is a global challenge and poses a significant threat to public health and ecosystems. In this study, we synthesized a novel fenugreek gum-based polymer functionalized with dopamine (DA) and monomers dimethylamino ethyl methacrylate (DMA), acrylamide, and N, N, methylene bis acrylamide (MBA) as a crosslinker and TiO2 nanocomposite hydrogel photocatalytic degradation for environmental remediation. The nanocomposite hydrogel was determined using various analytical techniques such as FT-IR, XRD, FESEM, EDX, DRS-UV, TEM, LC-MS, and XPS. The optical band gap was at 2.81 eV, calculated from UV–visible DRS spectra. The XRD confirmed the crystalline and anatase phases. TEM, EDX, and XPS analyses defined the size, shape, chemical composition, and purity of synthesized FNG/DDM/TiO2 nanocomposite hydrogel. The resulting nanocomposite hydrogel photocatalyst effectively degraded hazardous pollutants such as methylene blue (MB) and Congo red (CR) organic dyes under visible light irradiation. The decomposition efficiency of Congo red is 95.27 % within 75 min and methylene blue is 73.26 % within 150 min. Moreover, the results of the trapping experiment revealed that the active species in the photocatalytic degradation process are holes (h+) and super oxide radicals (.O2-), more reactive species. The probable degradation intermediates and the degradation pathway were analyzed by LCMS analysis, and the degradation fragments formed during Congo red (CR) dye degradation were identified. The recyclability and stability were studied in the presence of a photocatalyst, achieving 90.5 % degradation after four cycles. The FNG/DDM/TiO2 hydrogel also effectively removed dyes from wastewater containing organic pollutants. The novel FNG/DDM/TiO2 nanocomposite hydrogel, synthesized through an environmentally friendly polymer, demonstrated high efficiency in degrading organic dyes, excellent recyclability with robust structural stability, and significant potential for photocatalytic degradation of wastewater across various industries.

Enhancing sustainability in sewage treatment: A least squares support vector regression-based modeling approach for optimizing regeneration conditions of iFeCu

Nanoparticles in wastewater treatment offer sustainable, efficient removal of persistent pollutants, with minimal resource usage and reusability. This study examines the reusability of immobilized iron‑copper nanoparticles (iFeCu) for sewage treatment. The effect of the regeneration condition of iFeCu including the regeneration time and temperature on the performance of iFeCu for sewage treatment was investigated. Moreover, a soft sensor model, namely principal component analysis discrimination analysis ensemble least squares support vector regression (PCA-DA-E-LSSVR) model was developed to predict the performance of iFeCu, and an online performance of the model was studied to evaluate its accuracy. Investigating regeneration conditions like time and temperature, it was found that iFeCu regenerated in 1 mol (M) sodium carbonate (Na2CO3) at 40 °C for 5 h performed comparably to that regenerated at 60 °C for 15 h. Higher regeneration temperatures (>40 °C) decreased carbon dioxide and monoxide emissions but reduced ammonia (NH3) removal by ∼22 %. Shorter regeneration times (<5 h) decreased Na2CO3-iFeCu interaction, leading to an ∼11 % NH3 removal reduction. The correlation coefficient, R2 value of 0.8514 was obtained for the proposed PCA-DA-E-LSSVR model. Overall, the developed model well-fits the nonlinear data in sewage treatment and provides acceptable ranges of online performance results.