Nanoparticles and nanofiltration for wastewater treatment: From polluted to fresh water

Role of advanced cleaning and sanitation techniques in biofilm prevention on dairy equipment

Biofilm formation on dairy equipment is a persistent challenge in the dairy industry, contributing to product contamination, equipment inefficiency, and economic losses. Traditional methods such as manual cleaning and basic chemical sanitation are discussed as foundational approaches, followed by an in-depth investigation of cutting-edge technologies, including clean-in-place systems, high-pressure cleaning, foam cleaning, ultrasonic and electrochemical cleaning, dry ice blasting, robotics, nanotechnology-based agents, enzymatic cleaners, and oxidizing agents. Enhanced sanitation techniques, such as dry steam, pulsed light, acidic and alkaline electrolyzed water, hydrogen peroxide vapor, microbubble technology, and biodegradable biocides, are highlighted for their potential to achieve superior sanitation while promoting sustainability. The effectiveness, feasibility, and limitations of these methods are evaluated, emphasizing their role in maintaining dairy equipment hygiene and reducing biofilm-associated risks. Additionally, challenges, such as equipment compatibility, cost, and regulatory compliance, are addressed, along with insights into future directions and innovations, including automation, smart cleaning systems, and green cleaning solutions. This review provides a comprehensive resource for researchers, industry professionals, and policymakers aiming to tackle biofilm formation in dairy production systems and enhance food safety, operational efficiency, and sustainability.

Sustainable approach for fabrication of pineapple agro-waste mediated cellulose nanocrystals embedded with Ag/Ag2O/ZnO nanocomposites for efficient removal of waterborne pathogens in wastewater

Biogenic nanocomposites (NCs) effectively purify contaminated water by eliminating pollutants caused by rapid urbanization, unrestrained industrial activities, and the proliferation of pathogenic organisms, addressing the critical water contamination crisis impacting global health. This study describes the synthesis of a sustainable biopolymer NC (BNC) by incorporating pineapple (Murusi variety) crop residue-based Ag/Ag2O/ZnO NCs and cellulose nanocrystals (CNCs) through an eco-friendly and sustainable approach. TEM analysis revealed cross-sectional diameters of 11 nm consisting of spherical-shaped Ag/Ag2O NPs (9 nm) arranged on nanoflower-shaped ZnO NPs (82 nm). XRD analysis confirmed that biogenic Ag, Ag2O, and ZnO NPs exhibit space groups Fm3m, Pn-3m, and P63mc respectively with Ag/Ag2O NPs forming face-centered cubic and ZnO NPs wurtzite crystal structures. FTIR validated the pure CNCs formation, while TGA and differential thermogravimetry (DTG) demonstrated high thermal stability at 370 °C. Ag/Ag2O NPs exhibited outstanding antibacterial activity at 2000 ppm, with inhibition zones of 20 mm against E. coli and 21 mm against S. aureus. In contrast, ZnO NPs demonstrated lower antibacterial activity with inhibition zones of 13 mm against E. coli and 14 mm against S. aureus. The Ag/Ag₂O/ZnO NCs displayed significant antibacterial activity against both strains with inhibition zones of 19 mm. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the NCs were determined to be 31.3 ppm and 62.5 ppm, respectively, for both bacterial strains. These findings highlight the superior antimicrobial properties of silver-based NCs compared to ZnO, suggesting their potential application in antimicrobial treatments. The developed BNC filter comprising of Ag/Ag2O/ZnO NCs 20 mg: CNCs: 50 g effectively removed Salmonella typhi from 1.2 L of contaminated wastewater through sequential filtration, exhibiting significant characteristics including sustainability, low production cost, water stability, easy recoverability, and high bacterial growth inhibition, making it a promising solution for water treatment applications.

Analysis of Metal-Organic Framework and Polyamide Interfaces in Membranes for Water Treatment and Antibacterial Applications

Integrating biocidal nanoparticles (NPs) into polyamide (PA) membranes shows promise for enhancing resistance to biofouling. Incorporating techniques can tailor thin-film nanocomposite (TFN) membranes for specific water purification applications. In this study, silver-based metal-organic framework Ag-MOFs (using silver nitrate and 1,3,5-benzentricarboxylic acid as precursors) are incorporated into PA membranes via three different methods: i) incorporation, ii) dip-coating, and iii) in situ ultrasonic techniques. The characterizations, such as top-surface and cross-section scanning and transmission microscopy, reveal that the incorporation methods for the modified TFN membranes substantially control morphology and surface characteristics. For example, the in situ ultrasonically interlayered Ag-MOFs showed the largest pores (average pore diameter of 14 Å ± 0.1), resulting in the highest water permeance (water flux of 10.9 LMH/bar for Na2SO4). It also show superior antifouling and anti-biofouling performance, with a flux recovery ratio (FRR) of 94.1% in both fouling tests due to its improved surface hydrophilicity and the antibacterial properties of incorporated Ag-MOFs. Conversely, the surface-grafted dip-coated Ag-MOFs offered the highest salt rejection, attributed to its highly negatively charged surface and a dense PA network with narrow pores (average pore diameter of 10 Å ± 0.06).

Adsorption of Brilliant Green Dye by Iron Oxide Nanoparticles Synthesized From the Leaf Extracts of Acacia jacquemontii

Phyto-mediated synthesis can be used for the sustainable fabrication of metallic nanoparticles (NPs). Ethanolic leaf extract of Acacia jacquemontii was used to phyto-fabricate iron oxide nanoparticles (FeO NPs). Synthesized FeO NPs were examined by various analytical techniques for their detailed chemical elemental and morphological features. High-performance thin-layer chromatography (HPTLC) was used for the analysis of the ethanolic extracts of the leaves, which ensured the presence of phenols and terpenoids in the extract. FeO NPs show a peak between 350-400nm when analyzed by UV-Vis spectroscopy, and the typical bands were found in the range of 745 cm-1 for Fe-O and 1595 cm-1, 3177 cm-1 for some other organic molecules by Fourier transform-infrared (FTIR). The spherical shape of FeO NPs was investigated with the help of a Field emission scanning electron microscope (FESEM) analysis which exhibited the size varied from 13.35 to 31.29 nm. Electron diffraction spectroscopy (EDS) confirmed the Fe, O, and C peaks, along with N, Cl, S, and K traces. The adsorption capacity of the FeO NPs for brilliant green (BG) dye was evaluated at different pH, dosages of adsorbent, and contact time. The highest adsorption parentage of 57.2% for 10 ppm BG dye was observed at 9 pH and 10 mg doses of FeO NPs. The highest absorption capacity of FeO NPs is 60 mg/g. The recyclability potential of the FeO NPs continuously decreased with the repletion of the cycle from first to fourth whose value reached 19.33% after the fourth cycle. Such phytofabricated FeO NPs and their application in the removal of organic could prove to be eco-friendly and economical.

Anti-protozoal potential of electrospun polymeric nanofiber composite membranes for treatment of contaminated drinking water

The effectiveness of conventional techniques for removal of water contaminants remains doubtful on micropollutants, including waterborne protozoa. To the best of knowledge, this study is the first highlighting the use of electrospun polymeric nanofiber composite membranes coated with metal nanoparticles against Cyclospora cayetanensis and Giardia lamblia in vitro. Plain and hybrid nanofiber membranes loaded with zinc oxide, copper oxide and silver nanoparticles were prepared, characterized, and used for filtration of contaminated drinking water. Comparison between membranes was achieved through water examination microscopically and molecularly, counting and viability assessment of trapped protozoa on the membranes after filtration. Moreover, the membranes were examined by scanning electron microscopy (SEM) for detection of the trapped Cyclospora oocysts and Giardia cysts ultrastructural changes. Results showed that following water filtration, no protozoa were detected microscopically and melting curves were not plotted. A statistically significant reduction in the number of viable Cyclospora oocysts and Giardia cysts incubated for 4 days was reported. By SEM, dramatic distortions were observed in the trapped protozoa on hybrid membranes with superiority of silver nanoparticles. We concluded that the electrospun polymeric nanofibers composite membranes can be considered a promising alternative to standard water filtration methods.

Microbe-assisted phytoremediation for sustainable management of heavy metal in wastewater - A green approach to escalate the remediation of heavy metals

Water pollution from Heavy metal (HM) contamination poses a critical threat to environmental sustainability and public health. Industrial activities have increased the presence of HMs in wastewater, necessitating effective remediation strategies. Conventional methods like chemical precipitation, ion exchange, adsorption, and membrane filtration are widely used but possess various limitations. These include high costs, environmental impacts, and the potential for generating secondary pollutants, highlighting the need for sustainable alternatives. Phytoremediation, enhanced by microbial interactions, offers an eco-friendly solution to this issue. The unique physiological and biochemical traits of plants, combined with microbial metabolic capabilities, enable efficient uptake and detoxification of HMs. Microbial enzymes play a crucial role in these processes by breaking down complex compounds, enhancing HM bioavailability, and facilitating their conversion into less toxic forms. Synergistic interactions between root-associated microbes and plants further improves metal absorption and stabilization, boosting phytoremediation efficiency. However, challenges remain, including the limited bioavailability of contaminants and plant resilience in highly polluted environments. Recent advancements focus on improving microbial-assisted phytoremediation through mechanisms like bioavailability facilitation, phytoextraction, and phytostabilization. Genetic engineering facilitates the altering of genes that control plant immune responses and growth which improves the ability of plants to interact beneficially with microbes to thrive in HM rich environments while efficiently cleaning contaminated wastewater. This review examines these strategies and highlights future research directions to enhance wastewater remediation using phytoremediation technologies.

Preparation of dandelion flower extract-based polyvinyl alcohol-chitosan-dandelion-CuNPs composite gel for efficient bacteriostatic and dye adsorption

A multifunctional composite gel with efficient bacteriostatic and dye adsorption properties was prepared using polyvinyl alcohol, chitosan, and soybean isolate protein as carriers, CuNPs prepared by green reduction of dandelion extract as bacteriostatic agent, and glutaraldehyde as cross-linking agent. The composite gel showed good inhibition capacity of Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa with the diameter of inhibition zone of 27.0-28.3 mm by agar diffusion method. The composite gel antibacterial rate remained above 90 % after 14 days of preparation. After 6 times reuse of composite gel in water, the antibacterial rate remained above 90 %, proving its good stability and reusability. Adding dandelion extract and CuNPs greatly improved the gel antioxidant property, acquiring free radical scavenging rate at 95.6 %. This composite gel had good biocompatibility and adsorption performance, and the maximum adsorption amount of methylene blue and methyl orange was 40.36 mg/g and 41.81 mg/g, respectively. To sum up, the green composition of composite gel has good antimicrobial performance and high dye adsorption, which holds significant promising for treating the water body pollution and protecting the environment. To build cost-effective antibacterial and dye adsorption process on a large-scale, in-depth exploration about this topic is still needed to develop.

An overview of deploying different treatment processes with membrane bioreactor for enhanced treatment of wastewaters: synergistic performances and reduced fouling of membrane

The membrane bioreactor (MBR) process synergistically combines biological treatment with membrane filtration, offering a compact design and enhanced operational flexibility. However, membrane fouling remains a critical bottleneck, limiting its widespread application, particularly in treating high-strength wastewater. Recent advances have demonstrated that integrating MBR systems with auxiliary processes such as adsorption, electrochemical treatments, algal-assisted systems, and others can significantly mitigate fouling and enhance treatment efficacy. This paper critically reviews various MBR hybrid configurations, examining their mechanisms, advantages, and limitations in terms of treatment performance and fouling control, while highlighting their potential to extend conventional MBR's applicability to challenging wastewaters and addressing operational challenges like economic viability and sustainability. Elaborated tables incorporating a wide variety of research studies within the realm of synchronization have been meticulously compiled to generate a comprehensive literature review.

Nanoparticles in drinking water: Assessing health risks and regulatory challenges

Nanoparticles (NPs) pose a significant concern in drinking water due to their potential health risks and environmental impact. This review provides a comprehensive analysis of the current understanding of NP sources and contamination in drinking water, focusing on health concerns, mitigation strategies, regulatory frameworks, and future perspectives. This review highlights the importance of nano-specific pathways, fate processes, health risks & toxicity, and the need for realistic toxicity assessments. Different NPs like titanium dioxide, silver, nanoplastics, nanoscale liquid crystal monomers, copper oxide, and others pose potential health risks through ingestion, inhalation, or dermal exposure, impacting organs and potentially leading to oxidative stress, inflammatory responses, DNA damage, cytotoxicity, disrupt intracellular energetic mechanisms, reactive oxygen species generation, respiratory and immune toxicity, and genotoxicity in humans. Utilizing case studies and literature reviews, we investigate the health risks associated with NPs in freshwater environments, emphasizing their relevance to drinking water quality. Various mitigation and treatment strategies, including filtration systems (e.g., reverse osmosis, and ultra/nano-filtration), adsorption processes, coagulation/flocculation, electrocoagulation, advanced oxidation processes, membrane distillation, and ultraviolet treatment, all of which demonstrate high removal efficiencies for NPs from drinking water. Regulatory frameworks and challenges for the production, applications, and disposal of NPs at both national and international levels are discussed, emphasizing the need for tailored regulations to address NP contamination and standardize safety testing and risk assessment practices. Looking ahead, this review underscores the necessity of advancing detection methods and nanomaterial-based treatment technologies while stressing the pivotal role of public awareness and tailored regulatory guidelines in upholding drinking water quality standards. This review emphasizes the urgency of addressing NP contamination in drinking water and provides insights into potential solutions and future research directions. Lastly, this review worth concluded with future recommendations on advanced analytical techniques and sensitive sensors for NP detection for safeguarding public health and policy implementations.

Advancements in nanoparticle-modified zeolites for sustainable water treatment: An interdisciplinary review

The contamination of water sources with heavy metals, dyes, and other pollutants poses significant challenges to environmental sustainability and public health. Traditional water treatment methods often exhibit limitations in effectively addressing these complex contaminants. In response, recent developments in nanotechnology have catalyzed the exploration of novel materials for water remediation, with nanoparticle-doped zeolites emerging as a promising solution. This comprehensive review synthesizes current literature on the integration of nanoparticles into zeolite frameworks for enhanced contaminant removal in water treatment applications. We delve into synthesis methodologies, elucidate mechanistic insights, and evaluate the efficacy of nanoparticle-doped zeolites in targeting specific pollutants, while also assessing considerations of material stability and environmental impact. The review underscores the superior adsorptive and catalytic properties of nanoparticle-doped zeolites, owing to their high surface area, tailored porosity, and enhanced ion-exchange capabilities. Furthermore, we highlight recent advancements in heavy metal and organic pollutant uptake facilitated by these materials. Additionally, we explore the catalytic degradation of contaminants through advanced oxidation processes, demonstrating the multifunctionality of nanoparticle-doped zeolites in water treatment. By providing a comprehensive analysis of existing research, this review aims to guide future developments in the field, promoting the sustainable utilization of nanoparticle-doped zeolites as efficient and versatile materials for water remediation endeavors.

Hydrochar as a bio-based adsorbent for heavy metals removal: A review of production processes, adsorption mechanisms, kinetic models, regeneration and reusability

The spread of heavy metals throughout the ecosystem has extremely endangered human health, animals, plants, and natural resources. Hydrochar has emerged as a promising adsorbent for removal of heavy metals from water and wastewater. Hydrochar, obtained from hydrothermal carbonization of biomass, owns unique physical and chemical properties that are highly potent in capturing heavy metals via surface complexation, electrostatic interactions, and ion exchange mechanisms. This review focuses on removing heavy metals by hydrochar adsorbents from water bodies. The article discusses factors affecting the adsorption capacity of hydrochars, such as contact time, pH, initial metal concentration, temperature, and competing ions. Literature on optimization approaches such as surface modification, composite development, and hybrid systems are reviewed to enlighten mechanisms undertaking the efficiency of hydrochars in heavy metals removal from wastewater. The review also addresses challenges such as hydrochar regeneration and reusability, alongside potential issues related to its disposal and metal leaching. Integration with current water purification methods and the significance of ongoing research and initiatives promoting hydrochar-based technologies were also outlined. The article concludes that combining hydrochar with modern technologies such as nanotechnology and advanced oxidation techniques holds promise for improving heavy metal remediation. Overall, this comprehensive analysis provides valuable insights to guide future studies and foster the development of effective, affordable, and environmentally friendly heavy metal removal technologies to ensure the attainment of safer drinking water for communities worldwide.

MOF-Based Membranes for Remediated Application of Water Pollution

Membrane separation plays a crucial role in the current increasingly complex energy environment. Membranes prepared by metal-organic framework (MOF) materials usually possess unique advantages in common, such as uniform pore size, ultra-high porosity, enhanced selectivity and throughput, and excellent adsorption property, which have been contributed to the separation fields. In this comprehensive review, we summarize various designs and synthesized strategies of free-standing MOF and composite MOF-based membranes for water treatment. Special emphases are given not only on the effects of MOF on membrane performance, removal efficiencies, and elimination mechanisms, but also on the importance of MOF-based membranes for the applications of oily and micro-pollutant removal, adsorption, separation, and catalysis. The challenges and opportunities in the future for the industrial implementation of MOF-based membranes are also discussed.

Novel S-N/WO3: Optimization of photocatalytic performance of WO3 by simultaneous existence of S and N in WO3 against MB dye

In this work, pure and S-N/WO3 (1%-7%) nanoparticles (NPs) have been developed for the degradation of MB dye. Optical properties, vibrational analysis, morphology, structural analysis, and photocatalytic activity of the samples have been evaluated using a variety of characterization techniques, including UV-vis, PL, FTIR, SEM, and x-ray diffraction (XRD). The XRD patterns showed that the stability of the orthorhombic phase of WO3 was affected by the concentrations of S and N. In SEM, nanospheres with an average size of 80 nm of NPs have been observed. The PL results showed that the e-, h+ recombination rate for the S-N7%/WO3 sample was the lowest. The degradation of MB dye has also been investigated in order to investigate the photocatalytic performance. Remarkably, S-N7%/WO3 shows the best results, with a maximum degradation of 90% in 120 min. The stability of the improved catalyst was tested using recycling and trapping studies. S-N7%/WO3 catalyst's exceptional photocatalytic activity highlights its potential use in wastewater treatment. This study will be helpful for manufacturing innovation.

Adsorption of Heavy Metal Ions on Alginate-Based Magnetic Nanocomposite Adsorbent Beads

Graphene oxide and its magnetic nanoparticle-based composites are a well-known tool to remove heavy metals from wastewater. Unfortunately, one of the major issues in handling such small particles consists of their difficult removal from treated wastewater (even when their magnetic properties are exploited), due to their very small diameter. One possible way to overcome this problem is to embed them in a macroscopic biopolymer matrix, such as alginate or chitosan beads. In this way, the adsorbent becomes easier to handle and can be used to build, for example, a packed column, as in a traditional industrial adsorber. In this work, the removal performances of two different embedded magnetic nanocomposite adsorbents (MNAs) are discussed. The first type of MNA is based on ferrite magnetic nanoparticles (MNPs) generated by coprecipitation using iron(II/III) salts and ammonium hydroxide, while the second is based on a 2D material composed of MNP-decorated graphene oxide. Both MNAs were embedded in cross-linked alginate beads and used to treat artificial water contaminated with chromium(III), nickel(II), and copper(II) in different concentrations. The yield of removal and differences between MNAs and non-embedded magnetic nanomaterials are also discussed. From the results, it was found that the time to reach the adsorption equilibrium is higher when compared to that of the nanomaterials only, due to the lower surface/volume ratio of the beads, but the adsorption capacity is higher, due to the additional interaction with alginate.

Polysaccharide nanocomposites in wastewater treatment: A review

In modern times, wastewater treatment is vital due to increased water contamination arising from pollutants such as nutrients, pathogens, heavy metals, and pharmaceutical residues. Polysaccharides (PSAs) are natural, renewable, and non-toxic biopolymers used in wastewater treatment in the field of gas separation, liquid filtration, adsorption processes, pervaporation, and proton exchange membranes. Since addition of nanoparticles to PSAs improves their sustainability and strength, nanocomposite PSAs has gained significant attention for wastewater treatment in the past decade. This review presents a comprehensive analysis of PSA-based nanocomposites used for efficient wastewater treatment, focusing on adsorption, photocatalysis, and membrane-based methods. It also discusses potential future applications, challenges, and opportunities in adsorption, filtration, and photocatalysis. Recently, PSAs have shown promise as adsorbents in biological-based systems, effectively removing heavy metals that could hinder microbial activity. Cellulose-mediated adsorbents have successfully removed various pollutants from wastewater, including heavy metals, dyes, oil, organic solvents, pesticides, and pharmaceutical residues. Thus, PSA nanocomposites would support biological processes in wastewater treatment plants. A major concern is the discharge of antibiotic wastes from pharmaceutical industries, posing significant environmental and health risks. PSA-mediated bio-adsorbents, like clay polymeric nanocomposite hydrogel beads, efficiently remove antibiotics from wastewater, ensuring water quality and ecosystem balance. The successful use of PSA-mediated bio-adsorbents in wastewater treatment depends on ongoing research to optimize their application and evaluate their potential environmental impacts. Implementing these eco-friendly adsorbents on a large scale holds great promise in significantly reducing water pollution, safeguarding ecosystems, and protecting human health.

Popcorn-stick-like NH2-UiO-66/TiO2 nanotube nanocomposites toward optimized photocatalytic carbon oxidation with nitrogen dioxide

Developing photocatalytic technologies for pollutants removal with high harmless product selectivity is a significant challenge. Construction and optimization of nanocomposites junction with appropriate band alignments is an effective method for achieving this objective. Herein, a unique popcorn-stick-like NH2-UiO-66/TiO2 nanotube nanocomposites with staggered band alignment is fabricated. The small metal organic frameworks (MOFs) particles with diameters around 20 nm are uniformly dispersed on the surface of TiO2 nanoplates, creating a popcorn-stick-like structure. The resulting as-synthesized nanocomposites photocatalysts show distinguished photocatalytic activity for simultaneous removal of carbon particles and nitrogen dioxide with 100% NO2 conversion and 99% N2 selectivity, about 3.9 times higher than that of pristine TiO2. The significant enhancement is attributed to the rapid charge separation and transfer in TiO2 and NH2-UiO-66 interface and the visible light absorption. The enhanced charge transfer follows double charge transfer mechanism, which is confirmed by surface photovoltage spectroscopy, photoluminescence, transient photocurrent measurements, and electrochemical impedance spectroscopy. This study demonstrates the potential for the simultaneously removal of two pollutants using the composite of TiO2 and MOF materials with high surface area and visible light absorption ability, thereby providing the possible applications of NH2-UiO-66/TiO2 composites in environmental remediation including air purification and wastewater treatment.