Conventional Remediation Research Articles

Microbe–plant–nanoparticle interactions: role in bioremediation of petroleum hydrocarbons

ABSTRACT Petroleum hydrocarbons (PHCs) are organic substances that occur naturally on earth. PHCs have emerged as one of the most prevalent and detrimental contaminants in regions comprising soil and water resources. The limitations of conventional physicochemical and biological remediation solutions could be solved by combining remediation techniques. An effective, affordable, and environmentally benign method of reducing petroleum toxins is provided by the advanced idea of bioremediation, which has evolved into nanobioremediation. Environments contaminated with PHCs have been restored through microbe–plant–nanoparticle (NP)-mediated remediation, this review emphasizes how various metallic NPs interact with microbes and plants changing both their activity and that of enzymes, therefore accelerating the remediation process. This work further examines the challenges and possible uses of nanobioremediation, as well as the application of novel technologies in the interactions between bacteria, plants, and NPs for the bioremediation of PHCs. Furthermore, it has been shown that the use of plant-based, microbe-based, microbe–plant-based, and microbe–plant–NP-based techniques to remediate contaminated soils or water bodies is economical and environmentally beneficial. Microbial consortia have been reported as the treasure houses for the cleaning and recovery of hydrocarbon-contaminated environments, and the development of technologies for bioremediation requires an understanding of hydrocarbon degradation mechanisms.

Enhancing Microplastic Degradation through Synergistic Photocatalytic and Pretreatment Approaches.

Microplastics (MPs) pollution has emerged as a pressing environmental concern in recent years. Owing to their minute dimensions, conventional plastic remediation approaches are inadequate for addressing the challenges posed by MPs. Herein, spherical (BOC-S) and nanosheet (BOC-N) BiOCl photocatalysts were prepared and applied to the degradation of poly(ethylene terephthalate) (PET) MPs after hydrothermal pretreatment. The results indicated that the degradation efficiency of pretreated PET MPs using BOC-S and BOC-N photocatalysts was 8.8 and 6.9 times that of the unpretreated MPs under the same conditions. Comparative experiments confirmed the excellent performance of the photocatalysis-pretreatment system. The creation of pores on the surface of pretreated PET MPs facilitates the entry of active substances into the interior to cause damage, while the enhancement of hydrophilicity and specific surface area facilitates the contact between the catalyst and PET MPs, thus increasing the degradation efficiency. Free radical trapping experiments revealed that hydroxyl radicals (·OH) produced by photocatalysis had the greatest influence on the degradation performance of pretreated PET MPs. Finally, a possible photocatalytic degradation mechanism for PET MPs was proposed. This research offers a novel perspective on MPs degradation, providing valuable insights for advancing the efficacy of the process.

Efficient visible-light-driven photocatalytic degradation of indoor formaldehyde using an indium-based MOF/graphene oxide composite

Formaldehyde (HCHO) severely degrades indoor air quality, and conventional remediation methods are often inadequate for addressing low concentrations of HCHO indoors. In this study, we synthesized a MIL-68(In)-NH2/graphene oxide (GO) composite using a solvothermal method, aimed specifically at enhancing the photocatalytic degradation of HCHO under visible light. Our results show that the integration of GO enhances visible light absorption and facilitates efficient electron transport, significantly improving photocatalytic performance. The MIL-68(In)-NH2/GO composite achieves a 77 % degradation rate of HCHO, significantly outperforming MIL-68(In)-NH2 (51 %) and GO (22 %) alone. This enhanced activity is attributed to the effective separation of electron-hole pairs and synergistic interactions within the composite. We proposed an enhanced photocatalytic mechanism for the MIL-68(In)-NH2/GO system, identifying h+ and •O2– as the principal active species. Moreover, the MIL-68(In)-NH2/GO composite shows excellent reusability and stability, making it a promising candidate for eco-friendly and efficient indoor air purification using metal–organic frameworks.

Appraisal of Characterization and Adsorption Isotherm in the Bioremediation of Cu and Zn Ions from Aqueous Solutions Exploiting Unmodified Corn and Coconut Husk

Environment is contaminated by heavymetals has emerged as a substantial globaly. Conventional remediation methods have proven inadequate and costly in addressing this issue. Hence, there is a pressing need to discover bio-remediation as a cost effective, effectual, and environmentally, a substitute for heavymetal removal. This work investigates the adsorption behaviour of Corn Husk (CH) and Coconut Husk (CCH), an inexpensive adsorbent, towards Cu and Zn ions for potential application in wastewater treatment. The physico-chemical variables of unmodified CH and CCH were appraised, and batch experimental methods were employed to study variables like pH, contact time, size of particle, and preliminary content of metals. The impact of solution pH on metals uptake by the adsorbent was investigated on the pH range of 3 to 8, revealing optimal removal efficiencies at pH 6 for Cu and pH 5 for Zn. Equilibrium adsorption times were determined to be 80 minutes for Cu and 60 minutes for Zn ions onto CH and CCH. adsorption volumes is conforming to mono-layer coverage, attained from the Langmuir plots were 4.792 mg/g and 4.594 mg/g respectively for Cu and Zn metals onto the CH and 4.771 mg/g and 4.400 mg/g for their adsorption onto CCH. Experimental values were confirmed to the Langmuir model and Freundlich model, with the Langmuir model providing the best fit. The CH based adsorbent was generally found to have an increased capacity of adsorption of the metal contents than Coconut husk (CCH). These findings underscore the strength of Corn husk as an active adsorbent to extract cationic heavymetal contents from industrial effluents.

Bioinspired, Carbohydrate-Containing Polymers Efficiently and Reversibly Sequester Heavy Metals.

Water scarcity and heavy metal pollution are significant challenges in today's industrialized world. Conventional heavy metal remediation methods are often inefficient and energy-intensive, and produce chemical sludge. To address these issues, we developed a bioinspired, carbohydrate-containing polymer system for efficient and selective heavy metal removal. Using ring opening metathesis polymerization, we synthesized polymers bearing amphiphilic glucuronate side chains capable of selectively binding heavy metal cations in mixed media. In samples containing high concentrations of heavy metals (>550 ppb), these polymers rapidly form a filterable precipitate upon metal capture, reducing the concentration of cation to <1.5 ppb within 3 min, as measured by inductively coupled plasma mass spectrometry. This system effectively removes cadmium ions from highly contaminated solutions to levels below the Agency for Toxic Substances and Disease Registry limit for Cd2+ in drinking water and selectively removes both Cd2+ and Pb2+ from lake water spiked with trace amounts of metal. Acidification triggers protonation of the glucuronate groups, releasing the heavy metals and resolubilizing the polymer. This capture-and-release process can be repeated over multiple cycles without loss of binding capacity. As such, this study introduces a novel class of recyclable materials with pH-responsive properties, offering potential for applications in water remediation and beyond.

Mechanism and application of bacterial exopolysaccharides: An advanced approach for sustainable heavy metal abolition from soil

The escalation of heavy metal pollutants in soils and effluents, driven by industrialization and human activities, poses significant environmental and health risks. Conventional remediation methods are often costly and ineffective, prompting a shift towards sustainable alternatives such as biological treatments. Natural biosorbents, including microbial cells and their byproducts, have emerged as promising solutions. One such approach involves leveraging exopolysaccharides (EPS), complex high-molecular-weight biopolymers synthesized by microbes under environmental stress conditions. EPS are intricate organic macromolecules comprising proteins, polysaccharides, uronic acids, humic compounds, and lipids, either located within microbial cells or secreted into their surroundings. Their anionic functional groups enable efficient electrostatic binding of cationic heavy metals, making EPS effective biosorbents for soil remediation. This review thoroughly explores the pivotal role of bacterial EPS in the removal of heavy metals, focusing on EPS biosynthesis mechanisms, the dynamics of interaction with heavy metals, and case studies that illustrate their effectiveness in practical remediation strategies. By highlighting these aspects, the review underscores the innovation and practical implications of EPS-based bioremediation technologies, demonstrating their potential to address critical environmental challenges effectively while paving the way for sustainable environmental management practices. Key findings reveal that EPS exhibit robust metal-binding capacities, facilitated by their anionic functional groups, thereby offering a promising solution for mitigating metal pollution in diverse environmental matrices.

Electrocatalytic hydrogen evolution coupled with dye hydrogenation reactions for sustainable wastewater treatment using transition-metal (Fe, Co, Ni, Cu) nanoparticles with ZnO nanowire supports

A water electrolysis coupled with chemical reduction strategy is proposed to realize sustainable wastewater treatment. Correspondingly, a series of transition-metal (e.g., iron, cobalt, nickel and copper) nanoparticles anchored on zinc oxide nanowire array (ZnO NA) with bifunctional catalytic activity for hydrogen evolution reaction together with dye hydrogenation reaction (HER/DHR) are developed, while their catalytic activity are comparatively investigated at the same time. This renewable strategy with environmental and economic benefits exhibits high-efficiency treatment capability towards various dye wastewaters. For example, a typical system based on nickel nanoparticles with ZnO NA supports, which exhibits higher catalytic activity towards the HER/DHR than those of other three counterparts under the same conditions, can transform waste 4-nitrophenol into valuable 4-aminophenol with an apparent rate constant of 36.95 × 10-3 min−1 and a conversion rate of 98.32 %, thereby achieving dye decolorization and resource regeneration simultaneously. Its efficiency is significantly superior to that of chemical method dependent on traditional reducing agents and commercial nickel materials, demonstrating its stronger competitiveness. It is mainly benefited from the interface synergistic effect of nickel nanoparticles and zinc oxide nanowires. This novel system is expected to replace conventional sewage remediation technologies for efficient, inexpensive, and eco-friendly dye degradation, and thus is very important for energy and environmental sustainability.

Cd(II) and Zn(II) adsorption on lignite‐derived humic substances and cattle manure biochar

AbstractExcessive industrial release of trace elements may pose a great risk to the environment. Conventional remediation treatments have considerable limitations, making less expensive new technologies an important research area. Batch experiments were conducted at room temperature to investigate the use of two lignite‐derived humic products (nano‐humus and humic powder) and a cattle manure biochar as adsorbents in the removal of cadmium and zinc from laboratory synthesized water. Nano‐humus was most effective in adsorbing Cd(II), wherein 89% adsorption was rapidly achieved in 15 min. The adsorbed amount of Cd(II) and Zn(II) both increased with initial metal ion concentrations from 25 to 125 mg L−1. Despite being produced from the same sources, nano‐humus and humic powder showed different properties and adsorption behaviors. The adsorption mechanism of nano‐humus followed the Freundlich isotherm model and pseudo‐second‐order kinetic model, indicating multilayer chemisorption. Humic powder followed the pseudo‐second‐order kinetic model, although it had a low isotherm model fit, implying chemisorption‐dominated adsorption. Cattle manure biochar followed the Freundlich isotherm and pseudo‐first‐order kinetics model, suggesting diffusion‐dominated multilayer adsorption. Of the three adsorbents tested, nano‐humus had greatest potential as an effective and inexpensive material for metal remediation.

Polycyclic aromatic hydrocarbon: underpinning the contribution of specialist microbial species to contaminant mitigation in the soil.

The persistence of PAHs poses a significant challenge for conventional remediation approaches, necessitating the exploration of alternative, sustainable strategies for their mitigation. This review underscores the vital role of specialized microbial species (nitrogen-fixing, phosphate-solubilizing, and biosurfactant-producing bacteria) in tackling the environmental impact of polycyclic aromatic hydrocarbons (PAHs). These resistant compounds demand innovative remediation strategies. The study explores microbial metabolic capabilities for converting complex PAHs into less harmful byproducts, ensuring sustainable mitigation. Synthesizing literature from 2016 to 2023, it covers PAH characteristics, sources, and associated risks. Degradation mechanisms by bacteria and fungi, key species, and enzymatic processes are examined. Nitrogen-fixing and phosphate-solubilizing bacteria contributions in symbiotic relationships with plants are highlighted. Biosurfactant-producing bacteria enhance PAH solubility, expanding microbial accessibility for degradation. Cutting-edge trends in omics technologies, synthetic biology, genetic engineering, and nano-remediation offer promising avenues. Recommendations emphasize genetic regulation, field-scale studies, sustainability assessments, interdisciplinary collaboration, and knowledge dissemination. These insights pave the way for innovative, sustainable PAH-contaminated environment restoration.

Recent advancements in encapsulation of poly aromatic hydrocarbons via macrocyclic host-guest chemistry

Polyaromatic hydrocarbons (PAHs) pose a significant threat to ecosystems and human health due to their widespread presence and persistence in the environment. Conventional remediation techniques often fall short in both efficiency and environmental impact. However, recent advancements in utilizing organic macrocyclic host molecules show considerable promise for effectively sequestering and eliminating PAHs across diverse media. These macrocyclic host molecules play a central role in host–guest chemistry and supramolecular chemistry. It offers distinct advantages by virtue of their precisely tailored cavities and customizable functionalities, greatly enhancing their selective recognition abilities towards guest PAHs. The pursuit of designing and synthesizing novel functional macrocycles has captivated the attention of researchers, driven by the quest to address various challenges in supramolecular research. Over decades of dedicated exploration in host–guest chemistry and supramolecular chemistry, an expansive array of macrocyclic host molecules, constructed from diverse building blocks, have emerged as pivotal tools for encapsulating PAHs. This review presents an overview of the recent progress in the design, synthesis, and application of purely organic macrocyclic molecules in the encapsulation of PAHs. It elucidates the underlying principles that govern their ability to recognise PAHs, such as host–guest interactions, shape complementarity, and π-π stacking interactions. Furthermore, the review discusses various experimental methodologies, such as spectroscopic analyses, chromatography, and computational modelling, employed to assess the efficiency of organic cage molecules in PAH trapping. Additionally, considerations regarding the scalability and environmental implications of organic cage-based PAH trapping systems are addressed. The insights gleaned from this research provide valuable guidance for the development of robust strategies to combat PAH pollution in diverse environmental contexts.

UPTAKE OF Co(II), Pb(II) AND Ni(II) IONS BY Annona senegalensis STEM BARK BIOCHAR FROM AQUEOUS SOLUTION: OPTIMIZATION, KINETIC AND THERMODYNAMIC STUDIES

The concern for heavy metal pollution in the environment is especially so since they are non-biodegradable. The use of agro materials in the removal of these heavy metal pollutants has been recognized as a low-cost alternative to the costly conventional remediation techniques. The equilibrium sorption of the chemically activated Anonna senegalensis stem bark was investigated. Using standard techniques, the physicochemical properties of activated carbon (MAASC) were ascertained. By using a simultaneous batch adsorption approach, the adsorption of Co2+, Pb2+, and Ni2+ onto MAASC was examined as a function of pH, solution temperature, initial metal ion concentration, agitation time, adsorbent dose, particle size, and carbonization temperature. The equilibrium sorption data generated were fitted into Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models as well as pseudo first-order, pseudo-second-order and intraparticle diffusion kinetic models. From the obtained results, it was discovered that the Langmuir isotherm provided the best match conformation of all the models, except for Pb2+, which was best for Freundlich with an R2 of 0.95. Physisorption was shown to be the mechanism by Dubinin-Radushkevich. For Co2+, Pb2+, and Ni2+, respectively, the pseudo second-order kinetic model had R2 values of 0.997, 0.999, and 0.999 that best matched the data. Both intraparticle diffusion and the boundary layer effect also contributed to regulating the rates of the adsorption process. The study's thermodynamic results showed that Ho for Co2+, Pb2+, and Ni2+ were 27.51, 19.70, and 13.37 KJ/mol, respectively. These values are all positive and suggest an endothermic reaction, supporting the physisorption mechanism.

The role of microplastics in the process of Paraclostridium sp. DLY7-assisted phytoremediation of phenanthrene contaminated soil

Microplastics can absorb polycyclic aromatic hydrocarbons (PAHs), decrease the bioavailability of pollutants, alter the soil microbial community, and thus might affect the dissipation of soil pollutants. However, whether microplastics could alter the remediation efficiency of PGPR-assisted plants for PAHs-contaminated soil has not been studied. This study assessed the remediation potential of PGPR exhibiting phenanthrene (PHE) degradation ability in assisting maize for PHE-contaminated soil. Especially, the role of microplastics involved in this remediation process was also investigated. The results showed that strain Paraclostridium sp. DLY7 (DLY7) significantly increased the PHE removal efficiency (63.4%) from soil by maize and reduced the content of PHE in maize leaves and roots with no microplastics addition. However, the presence of microplastics significantly inhibited the PHE removal from soil and increased the PHE accumulation in maize issues, in comparison with PHE + DLY7 treatment. Microplastics also significantly reduced soil sucrase and alkaline phosphatase activities, and the content of soil nitrate nitrogen and ammonium nitrogen under non-inoculation with strain conditions. Inoculation with strain DLY7 also altered the rhizosphere soil microbial community, enriched some beneficial bacteria and increased activities of some crucial soil enzymes, thus facilitating PHE removal from soil. On the whole, compared with conventional soil contamination remediation studies, this study innovatively pointed out that microplastics significantly reduced the removal efficiency of soil PHE and increased the uptake of PHE by maize in the PGPR-assisted phytoremediation process. However, the effects of microplastics on microorganisms might be related to the particle size, concentration and type of microplastics in the environment, which would be studied in our future research. These findings proposed new perspectives for revealing the role of microplastics on the efficiency of microbe-assisted phytoremediation of PAHs-contaminated soil.

Assisted phytoextraction as a nature-based solution for the sustainable remediation of metal(loid)-contaminated soils.

Soil contamination is a significant environmental issue that poses a threat to human health and the ecosystems. Conventional remediation techniques, such as excavation and landfilling, are often expensive, disruptive, and unsustainable. As a result, there has been growing interest in developing sustainable remediation strategies that are cost-effective, environmentally friendly, and socially acceptable. One such solution is phytoextraction: a nature-based approach that uses the abilities of hyperaccumulator plants to uptake and accumulate metals and metalloids (potentially toxic elements [PTE]) without signs of toxicity. Once harvested, plant biomass can be treated to reduce its volume and weight by combustion, thus obtaining bioenergy, and the ashes can be used for the recovery of metals or in the construction industry. However, phytoextraction has shown variable effectiveness due to soil conditions and plant species specificity, which has led researchers to develop additional approaches known as assisted phytoextraction to enhance its success. Assisted phytoextraction is a remediation strategy based on modifying certain plant traits or using different materials to increase metal uptake or bioavailability. This review article provides a practical and up-to-date overview of established strategies and the latest scientific advancements in assisted phytoextraction. Our focus is on improving plant performance and optimizing the uptake, tolerance, and accumulation of PTE, as well as the accessibility of these contaminants. While we highlight the advantages of using hyperaccumulator plants for assisted phytoextraction, we also address the challenges and limitations associated with this approach. Factors such as soil pH, nutrient availability, and the presence of other contaminants can affect its efficiency. Furthermore, the real-world challenges of implementing phytoextraction on a large scale are discussed and strategies to modify plant traits for successful phytoremediation are presented. By exploring established strategies and the latest scientific developments in assisted phytoextraction, this review provides valuable guidance for optimizing a sustainable, nature-based technology. Integr Environ Assess Manag 2024;20:2003-2022. © 2024 SETAC.

Sustainable and integrated approaches for carbon capture and rapid remediation of Cr- and Zn-contaminated soils

Soil contamination is a growing concern for sustainable development worldwide. Conventional remediation approaches, such as using ordinary Portland cement (OPC) or lime are limited due to high CO2 emissions, energy consumption, and natural resource consumption. This paper proposes a sustainable method using CO2 and a waste from steel production (ladle slag, LS) for rapid remediation of Cr and Zn-contaminated soils. Contaminated soils spiked by Cr and Zn with various initial concentrations were treated with 10% LS and subjected to conventional and CO2 curing for different periods. The results demonstrated that LS with conventional curing could reduce leaching concentrations of Cr and Zn in contaminated soils. However, it necessitated 28 days to meet the criteria of inert waste and drinking water standards. In contrast, LS with CO2 curing required significantly less time (32 h for Cr and 8 h for Zn) to achieve lower leaching concentrations of Cr and Zn than those with 28-day conventional curing. After CO2 curing for 152 h for Cr- and 80–120 h for Zn-contaminated soils, leaching concentrations of Cr and Zn were 1.5–4 times and 6–72 times lower than those with 28-day conventional curing, respectively. Simultaneously, carbon capture was increased from 10.6% to 17.5% and 19.9%, respectively, with the initial Cr and Zn concentrations increased from 0 to 8000 mg/kg. The strength of Cr- and Zn-contaminated soils with CO2 curing also effectively enhanced up to around 3.3–3.6 times and 1.3–3.3 times higher than those with 28-day conventional curing, respectively.

Role of Extremophiles in Biodegradation of Emerging Pollutants

AbstractEmerging pollutants, also referred to as emerging contaminants, are substances that have recently been recognized or are gaining attention due to their potential adverse impacts on the environment, human health, or ecosystems. These pollutants present a significant threat to both environmental and human well-being and are challenging to eliminate using conventional remediation methods. Extremophiles, organisms adapted to extreme environmental conditions like high or low temperatures, high pressure, and elevated salt concentrations, play a crucial role in this context. They produce a diverse array of enzymes capable of breaking down complex organic compounds, some of which remain stable and functional even in harsh environmental conditions, making extremophiles well-suited for use in bioremediation applications. Numerous studies have demonstrated the capability of extremophiles to degrade various pollutants, including toxic solvents, heavy metals, and industrial chemicals. Halophilic archaea, a type of extremophile, have particularly shown promise in degrading emerging contaminants in salt marsh sediments. Despite their potential, there are challenges associated with using extremophiles in bioremediation, such as the limited availability of extremophilic microorganisms capable of degrading specific pollutants and a reduction in enzyme stability when operating outside their optimum range. Nevertheless, ongoing research in this field is anticipated to result in the development of new and innovative bioremediation strategies for effectively removing emerging pollutants from the environment.

Biosorption of Triphenylmethane (TPM) Dyes by Microbial Biomass: A Review

Many organic and inorganic contaminants are present in wastewater, and releasing them into receiving waterways causes major environmental problems. The wastewater produced by numerous industries contains a significant amount of dyes; this continues to be one of the most serious ecological issues confronting public health. Unfortunately, conventional wastewater remediation methods are incapable of completely removing dyes. Biosorption is the process by which living material removes chemicals from a solution. Organic, inorganic, gaseous, liquid, or insoluble substances are examples of such substances. Absorption, adsorption, ion exchange, surface complexation, and precipitation are all mechanisms involved in this physicochemical process. It is a characteristic shared by both live and dead biomass. Triphenyl methane dyes are a significant category of commercial dyes known for their remarkable color intensity, bright red, green, and blue colors, and low lightfastness on many substrates. In contrast to live biomass, using dead biomass in biosorption is more ideal since the hazardous nature of pollutants does not affect the sorption process. There is also no need to provide nutrients or maintain a growing environment. In addition to these variables, researchers discovered that dead biomass is more efficient than active biomass at absorbing organic contaminants. This review highlighted the toxicity of dyes, principles, and theory of the adsorption process, isotherm and kinetic studies of some microbial biosorbents, and thermodynamic studies of triphenyl methane dyes adsorption.

Catalytical Degradation of Industrial Dyes using Biosynthesized Nanoparticles - Review

The rapid growth of the textile industry has led to a surge in the release of industrial dyes, posing a severe environmental threat. An attempt was made in this review paper to explore the catalytical degradation of industrial dyes using biosynthesized nanoparticles as a promising avenue for sustainable remediation and to provide a thorough understanding of the advancements, challenges and potential applications of this innovative approach. The synthesis methods of biosynthesized nanoparticles were explained, highlighting the use of natural extracts and their inherent catalytic properties. A critical analysis of the catalytic degradation process was presented, examining the diverse range of industrial dyes targeted by biosynthesized nanoparticles. The factors influencing degradation efficiency, such as nanoparticle size, composition and the nature of the dye pollutants were investigated and the kinetics and mechanisms governing catalytic degradation were explored, shedding light on the intricacies of the reaction pathways. The environmental impact and sustainability of biosynthesized nanoparticles for dye degradation were thoroughly evaluated. Comparisons with conventional remediation methods were made, emphasizing the eco-friendly nature and potential scalability of this innovative approach. Moreover, challenges and future directions in this field were outlined to guide further research efforts.

Controlled-Release Materials for Remediation of Trichloroethylene Contamination in Groundwater

Groundwater contamination by trichloroethylene (TCE) presents a pressing environmental challenge with far-reaching consequences. Traditional remediation methods have shown limitations in effectively addressing TCE contamination. This study reviews the limitations of conventional remediation techniques and investigates the application of oxidant-based controlled-release materials, including encapsulated, loaded, and gel-based potassium permanganate since the year 2000. Additionally, it examines reductant controlled-release materials and electron donor-release materials such as tetrabutyl orthosilicate (TBOS) and polyhydroxybutyrate (PHB). The findings suggest that controlled-release materials offer a promising avenue for enhancing TCE degradation and promoting groundwater restoration. This study concludes by highlighting the future research directions and the potential of controlled-release materials in addressing TCE contamination challenges.

A concise overview of perchlorate sources, contamination, and remediation techniques

Perchlorate has become one of the most significant contaminants in our environment. Perchlorate is responsible for difficulties relating to both human and environmental health. In contaminated areas, microorganisms that degrade perchlorate are now promising bioremediation techniques. Microorganisms based on chemical, physical, and other biological approaches are favored for economic and environmental reasons. These microbes were accountable for the breakdown of perchlorate in the environment. This state-of-the-art review explores the perchlorate is a nonvolatile anion that is non-reactive and kinetically stable due to the most oxidized form of the chlorine atom. However, several industrial applications of perchlorate contamination have become a global concern. Perchlorate has several undesirable effects on the ecosystem as it degrades the environmental quality along with numerous anthropogenic activities. Currently, perchlorate-reducing microbes have proven to be a promising approach toward bioremediation. It can be hypothesized that bioreactors using perchlorate-reducing microbes would facilitate water treatment’s efficacy and prevent several deadly diseases caused by perchlorate contamination. Additionally, this study delves into innovative and conventional remediation techniques used to mitigate perchlorate contamination. It covers a wide range of strategies, including biological treatments, ion exchange, chemical reduction, and phytoremediation, among others. Furthermore, it discusses each technique’s advantages, limitations, and feasibility, considering factors such as cost, scalability, and site-specific conditions.

Nanotechnologies for environmental remediation and their ecotoxicological impacts.

Environmental nanoremediation is an emerging technology that aims to rapidly and efficiently remove contaminants from the polluted sites using engineered nanomaterials (ENMs). Inorganic nanoparticles which are generally metallic, silica-based, carbon-based, or polymeric in nature serve to remediate through chemical reactions, filtration, or adsorption. Their greater surface area per unit mass and high reactivity enable them to treat groundwater, wastewater, oilfields, and toxic industrial contaminants. Despite the growing interest in nanotechnological solutions for bioremediation, the environmental and human hazard associated with their use is raising concerns globally. Nanoremediation techniques when compared to conventional remediation solutions show increased effectivity in terms of cost and time; however, the main challenge is the ability of ENMs to remove contaminants from different environmental mediums by safeguarding the ecosystem. ENMs improving the accretion of the pollutant and increasing their bioavailability should be rectified along with the vigilant management of their transfer to the upper levels of the food chain which subsequently causes biomagnification. The ecosystem-centered approach will help monitor the ecotoxicological impacts of nanoremediation considering the safety, sustainability, and proper disposal of ENMs. The environment and human health risk assessment of each novel engineered nanomaterial along with the regulation of life cycle assessment (LCA) tools of ENMs for nanoremediation can help investigate the possible environmental hazard. This review focuses on the currently available nanotechnological methods used for environmental remediation and their potential toxicological impacts on the ecosystem.