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Bioremediation; Emerging contaminants; Environmental sustainability; Pharmaceuticals; Genetically engineered microbes; Bioaugmentation; microbial consortia; Synthetic biology; Nano-biotechnology; Bioelectrochemical systems

Introduction

Emerging contaminants (ECs), including pharmaceuticals, personal care products (PCPs), industrial chemicals, heavy metals, microplastics, and endocrine-disrupting chemicals, have become significant environmental pollutants. These contaminants are commonly found in water, soil, and sediments, and often persist in the environment due to their resistance to conventional treatment methods. In many cases, ECs are biologically active even at low concentrations, posing potential risks to ecosystems and human health through bioaccumulation and toxicity. Traditional treatment technologies, such as physical adsorption, chemical degradation, and high-temperature incineration, are often inefficient, expensive, or environmentally damaging. As a result, the need for more sustainable, effective, and eco-friendly solutions has led to an increased interest in bioremediation an environmentally friendly process that utilizes biological agents to remove or neutralize pollutants [1]. Bioremediation offers several advantages, including cost-effectiveness, low energy consumption, and the ability to break down pollutants into non-toxic or less toxic by-products. The natural biodegradation pathways of microorganisms, fungi, and plants provide a powerful tool to address the contamination of ECs in diverse environments. In recent years, several innovative approaches have emerged to enhance the efficiency of bioremediation for ECs [2]. Genetically engineered microorganisms (GEMs), designed to degrade specific pollutants, have shown substantial promise in degrading persistent contaminants, including pharmaceuticals, pesticides, and plastics. The development of microbial consortia, where different microbial species work synergistically to degrade complex mixtures of contaminants, has also been explored to increase degradation efficiency.

Moreover, the integration of synthetic biology and nano-biotechnology has introduced new strategies for accelerating biodegradation and improving pollutant bioavailability. Bioelectrochemical systems (BESs), which utilize microbial fuel cells to drive bioremediation processes, offer a promising avenue for addressing environmental pollution while also generating renewable energy [3-5]. Despite these advances, several challenges remain, including optimizing bioremediation processes under varied environmental conditions, ensuring the ecological safety of genetically engineered organisms, and scaling up laboratory findings to field-level applications. This review provides a comprehensive overview of the latest advances in the bioremediation of emerging contaminants, focusing on innovative strategies that enhance degradation rates, improve pollutant bioavailability, and contribute to long-term environmental sustainability.

Methodology

The innovative approaches in the bioremediation of emerging contaminants (ECs) are explored through a combination of laboratory-based experiments, field trials, and computational modeling. The methodologies used in the bioremediation of ECs focus on enhancing microbial degradation capabilities, optimizing environmental conditions, and integrating advanced biotechnologies [6]. The following techniques have been widely implemented:

Microbial engineering and bioaugmentation: Genetic Engineering of Microorganisms: Laboratory techniques involve the modification of microbial strains (e.g., bacteria, fungi) to enhance their ability to degrade specific pollutants. Gene cloning, mutagenesis, and synthetic biology are employed to insert or modify genes encoding for enzymes that can degrade emerging contaminants such as pharmaceuticals, pesticides, or microplastics. Bioaugmentation the introduction of pollutant degrading microbial consortia or single strains into contaminated sites is conducted to enhance bioremediation. Microbial consortia are chosen based on their synergistic interactions and collective degradation capabilities, targeting a wide range of contaminants [7].

Bioreactor design and bioelectrochemical systems (BESs): Bioreactor Setup: In laboratory trials, various types of bioreactors (batch, continuous flow, and immobilized systems) are used to simulate the bioremediation of ECs under controlled conditions. Parameters like temperature, pH, nutrient availability, and oxygen levels are adjusted to optimize microbial activity. Bioelectrochemical systems  BESs, including microbial fuel cells (MFCs) and microbial electrolysis cells (MECs), are employed to use microbial metabolism for both pollutant degradation and energy generation [8]. The interaction between microbes and electrodes in these systems can enhance the rate of biodegradation, providing an integrated approach for environmental cleanup and energy recovery.

Nanotechnology in bioremediation: Nanomaterials: Nanoparticles, such as nano-zero-valent iron (nZVI), magnetic nanoparticles, and carbon-based nanomaterials, are introduced into bioremediation systems to enhance pollutant adsorption and bioavailability. These materials facilitate the breakdown of complex pollutants by increasing the surface area and providing additional catalytic sites for microbial enzymes. Nanobiotechnology Integration fungi, bacteria, or algae are often used in conjunction with nanoparticles to facilitate the transformation of hazardous pollutants into less toxic forms. Nanomaterials enhance the interaction between pollutants and microbial enzymes, improving the efficiency of bioremediation processes.

Computational models and environmental simulations: Modeling Pollutant Degradation: Mathematical models, including kinetic models and reaction-diffusion models, are used to simulate the biodegradation of pollutants in various environmental conditions. These models help predict the optimal conditions for bioremediation and identify the key factors that influence degradation rates [9]. Environmental simulation field trials in natural water bodies and soils, combined with laboratory-controlled experiments, help assess the real-world applicability of bioremediation strategies. Environmental variables such as temperature, salinity, and pollution load are modeled to assess how different bioremediation techniques perform under variable conditions.

Results

Recent advances in the bioremediation of emerging contaminants have demonstrated significant success in both laboratory settings and preliminary field trials. Key findings include:

Genetic engineering of microorganisms: Enhanced Pollutant Degradation: Genetically engineered strains, such as modified Escherichia coli and Pseudomonas putida, have shown improved degradation rates of complex pollutants like acetaminophen, triclosan, and chlorpyrifos. The insertion of genes encoding for specific degrading enzymes (e.g., laccases, peroxidases, cytochrome P450s) led to enhanced degradation efficiency by up to 50% compared to wild-type strains (Chaudhary et al., 2022). Microbial consortia the use of mixed microbial communities has been effective in degrading a wider array of pollutants, especially in polluted environments where complex mixtures of ECs are present. In a study on pharmaceutical-contaminated water, a consortium of Bacillus, Pseudomonas, and Aspergillus species degraded ibuprofen and sulfamethoxazole by up to 60% within 10 days (Rizzo et al., 2020).

Bioelectrochemical systems (BESs): Increased Degradation Efficiency: BESs, such as microbial fuel cells (MFCs), have demonstrated the ability to degrade a range of ECs, including bisphenol A, antibiotics, and organic dyes, while simultaneously producing electricity. In one study, the MFC setup degraded caffeine by 72% within 48 hours, while generating 12.5 mW of electrical power, indicating the dual benefit of these systems for both remediation and energy recovery (Wang et al., 2021). Improved pollutant bioavailability in BESs, the addition of electrodes has been shown to increase the bioavailability of pollutants, enhancing microbial activity and degradation rates [10]. The ability of electrodes to shuttle electrons across microbial membranes has led to higher degradation efficiency of pharmaceutical pollutants in wastewater treatment systems.

Nanotechnology applications: Enhanced Pollutant Adsorption: Nanomaterials, particularly nano-zero-valent iron (nZVI), have shown excellent capabilities in adsorbing and reducing pollutants like heavy metals and organic solvents. In one experiment, nZVI particles removed cadmium (Cd) and lead (Pb) from contaminated water by up to 85% after 72 hours, significantly reducing their toxicity (Zhang et al., 2022). Nanobiotechnology synergy the integration of nano-biosorbents and microbial cultures has been shown to enhance the degradation of pesticides and pharmaceuticals. For instance, Pseudomonas putida cultured in combination with magnetic nanoparticles was able to degrade atrazine more effectively than when the microorganism was used alone, achieving over 90% degradation in 7 days (Li et al., 2023).

Conclusion

The bioremediation of emerging contaminants through innovative approaches is rapidly advancing, offering promising strategies for enhancing environmental sustainability. Genetic engineering, bioaugmentation, microbial consortia, bioelectrochemical systems, and nanotechnology have all been shown to significantly improve the efficiency of pollutant degradation. These strategies are particularly effective in addressing the complex and persistent nature of emerging contaminants, such as pharmaceuticals, pesticides, personal care products, and microplastics, which are difficult to remove using traditional treatment methods. However, several challenges remain, including the need to optimize environmental conditions for large-scale applications, the potential ecological risks of introducing genetically engineered organisms into natural ecosystems, and the economic feasibility of deploying these technologies in real-world environments. Additionally, scaling up laboratory-based successes to field-level applications requires careful consideration of site-specific factors such as pollutant concentrations, environmental variability, and the long-term sustainability of bioremediation processes. Future research should focus on improving the integration of these innovative technologies, enhancing microbial strain performance, and designing more effective bioreactor systems. Furthermore, interdisciplinary approaches combining biotechnology, nano-biotechnology, and environmental engineering will likely provide the most robust solutions for the large-scale remediation of emerging contaminants. As these innovative bioremediation methods continue to evolve, they hold the potential to contribute significantly to the restoration of contaminated ecosystems and the advancement of environmental sustainability.

Acknowledgement

None

Conflict of Interest

None

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