2.4.1 Bioremediation Methods Efficiency Assessment

In this section, we assessed the efficiency of microplastic remediation methods from three perspectives: economic, technological, and social. Our goal was to determine the effectiveness, efficiency, sustainability, safety, and economic viability of the chosen method (Figure 2).

2.4.2 Technological Aspect

The technological aspect is crucial in evaluating the efficiency of microplastic remediation methods. It impacts the effectiveness, efficiency, scalability, and safety of the remediation process. (i) Effectiveness: The method should effectively remove or neutralize microplastic. If the method is not effective, it may not justify the investment of time, money, and resources. (ii) Remediation Time: The duration required for remediation can influence the method's efficiency. If it takes too long, it may not be practical, especially in situations where prompt action is necessary. (iii) Operability: This refers to the ease of operating the remediation method. It includes factors such as the level of skill or training required, as well as the reliability and consistency of the technology under different conditions. (iv) Scalability: This refers to the ability of the method to be scaled up or down to meet different needs. It includes factors such as the technology's capacity to handle larger or smaller volumes of contaminated material and the impact of scaling on the effectiveness and efficiency (Table 1). (v) Implementation: This refers to the process of implementing the method, including the resources required and regulatory requirements and approvals needed.

2.4.3 Social Aspect

The social criteria for measuring the social performance and public acceptability of groundwater remediation technologies are as follows: (i) Effect on ecology: The remediation method should not harm the ecosystem or the organisms living within it. This criterion takes into consideration the potential impacts on biodiversity and ecosystem health. (ii) Effect on the environment: The method should not cause additional environmental damage or contribute to other forms of pollution. This criterion evaluates the overall environmental impact of the remediation method. (iii) Public health: The remediation method should not pose risks to public health. This includes potential exposure to hazardous substances during the remediation process or the introduction of new health risks.

2.4.4 Economic Aspect

The economic criteria used to measure the economic performance of groundwater remediation technologies are: capital cost, feedstock cost, and operation cost. (i) Capital cost refers to the initial investment required for the technology or method used for remediation, which can greatly impact its feasibility. If the capital cost is too high, it may not be a viable option for many organizations or communities. (ii) Detection and analysis costs encompass the expenses associated with detecting and analyzing microplastic, such as equipment, labor, and time. These costs can affect the overall efficiency and viability of the remediation method. (iii) On the other hand, operation and maintenance costs can accumulate over time and impact the long-term sustainability of the remediation method. If these costs are too high, the method may not be a practical solution in the long run.

2.4.5 Human Health Risk Level Assessment

To assess the potential human health risks associated with bioremediation, the following criteria were used: (i) Toxicity of contaminants method: Determine the toxicity of contaminants before and after bioremediation. Some contaminants may become less toxic, while others may become more toxic or mobile. (ii) Exposure pathways: Identify potential exposure pathways, such as ingestion, inhalation, or dermal contact. Consider how the bioremediation process may affect these pathways. (iii) Exposure duration and frequency: Determine the duration and frequency of exposure to any residual contaminants or by-products.

2.4.6 Quantification of the Bioremediation Effectiveness Methods and Human Health Risk Level Assessment

Based on the highest observed efficiency, the following categorizations were made: < 30%, 30%–70%, and > 70%, with scores of 1, 2, and 3 assigned, respectively. Comparing the removal efficiency of bioremediation methods is challenging due to variation in conditions and the use of different media. To overcome this difficulty, we focused on comparing the parameters used to evaluate the environmental friendliness of each method, specifically in the context of water sources as the medium.

3.1.1 Sources Distribution of Microplastics in the Environment

Initial screening was conducted using VOSviewer keyword co-occurrence analysis and Keywords Plus (Figure S1). This approach highlighted the most frequently studied and cited methods in microplastic bioremediation research, as well as widely applied methods in the literature. A total of 10 methods have been selected from the obtained studies after data screening, including biodegradation, mycoremediation, uptake and accumulation, rhizosphere, phytoextraction, floating, bioremediation using soil microorganisms, plant-assisted degradation, phytofiltration, and phytodegradation. We categorized the studies by the sources of microplastics (MPs), where applicable. Of the 827 studies that provided data on sources, 289 studies (35%) identified synthetic textiles as the main source, with no restrictions on the type of textiles. Another significant portion (28%, 232 studies) attributed tires as the primary source (Figure 3a). Among the remaining studies, 12% (99 studies) focused on city dust (urban particulate matter), 10% (83 studies) on road markings, 7% (58 studies) on personal care products, 5% (41 studies) on plastic bottles, and 3% (25 studies) on marine coatings (Figure 3a). Synthetic textiles predominantly release microplastics as tiny fibers through washing, wear and tear. Urban particulate matter serves as a complex mixture that can transport and contain microplastics from various sources. Furthermore, marine coatings, used to protect ships and marine structures, also contribute to MP pollution as they degrade and release plastic particles over time, particularly in aquatic environments.

3.1.2 Shape and Composition of Microplastics in the Environment

Additionally, 60% of the reviewed studies (496) identified fibers as the most prevalent shape of microplastics (MPs) in the environment (Figure 3b). These fibers, often originating from synthetic textiles, enter wastewater systems and contaminate various environmental compartments, including aquatic ecosystems and soil. The second most common shape, fragments, was reported in 25% (207 studies) of the studies. MP fragments result from the degradation of larger plastic items such as bags, bottles, and packaging materials through processes like photodegradation, mechanical abrasion, and biodegradation. They exhibit highly irregular shapes and vary greatly in size. Beads, commonly found in personal care products like exfoliants and toothpastes, were identified in 10% (83) of the studies (Figure 3b). Notably, the prevalence of beads in the environment may be decreasing due to recent bans on microbeads in cosmetics in several countries19. Lastly, foam particles, resulting from the degradation of expanded polystyrene products, were reported in 5% (41) of the studies (Figure 3b). These lightweight particles can be easily transported by wind and water, facilitating their widespread dispersal in the environment.

3.1.3 Exposure Routes of MPs

Exposure pathways for microplastics (MPs) can vary based on factors such as age, occupation, and lifestyle. Several studies have identified different routes through which MPs can enter the human body. A significant number of studies (70%, 111 studies) have detected MPs in various items, including contaminated water (78 studies) and food (33 studies). These food items include seafood, salt, honey, tap water, and bottled water, indicating that ingestion is one of the primary exposure routes (Figure 3c). Young children may be particularly susceptible to ingesting MPs through dust due to their hand-to-mouth behavior. Inhalation is another significant exposure route, with a considerable number of studies (25%, 40 studies) finding MPs in indoor air (12 studies) and outdoor air (28 studies) (Figure 3c). Major sources of airborne MPs include synthetic textiles, urban dust, and indoor dust, which can be easily inhaled, especially the smaller particles. Additionally, dermal penetration was examined in a smaller subset of the studies (5%, 8 studies) (Figure 3c). These studies found that some cosmetics and personal care products contain MPs that can contact the skin and enter the human body.

3.1.4 Human Body Microplastics Distribution and Impact

Many studies have examined microplastics (MPs) in human tissues and fluids (Figure 3d). The most extensively studied area is the presence of MPs in feces, specifically focusing on feces, lungs, and blood. The presence of MPs in feces with 40 studies (44%) confirmed that a significant amount of ingested microplastics is excreted, indicating ingestion as a major exposure route. MPs were also found in the lungs (35%, 32 studies), suggesting inhalation as another significant exposure route and potential implications for respiratory health. Furthermore, several studies (17%, 15 studies) have identified MPs in human blood (Figure 3d), suggesting that microplastics can be transported throughout the body and raising concerns about potential effects on cardiovascular health and other bodily systems.

Many studies have examined the health effects of microplastics exposure and have found a range of potential impacts (Figure 4). Specifically, 159 studies have shown that microplastics may contribute to various health issues, including neurodevelopmental disorders like attention deficit hyperactivity disorder, autism, and neurobehavioral deficits. These impacts have also been linked to decreased IQ, cognitive deficits, cardiovascular problems, circulatory system stresses, and endocrine disruption (Figure 4). In addition, other health effects associated with microplastics exposure include allergies, carcinogenicity, inflammation, immune response activation, hepatic fibrosis, and hepatic fibrotic disorders. Both male and female reproductive systems may be affected, with males experiencing subfertility, reduced sperm quality, and antiandrogen action, while females may face polycystic ovarian syndrome, endometriosis, delayed time to pregnancy, abnormal pap smears, pregnancy-induced hypertension, and/or preeclampsia.

Moreover, microplastics exposure has also been linked to adverse pregnancy outcomes such as preterm birth, lower birth weight, and abnormal genital structure (Figure 4). Metabolic disorders, including Type 2 diabetes, excessive childhood weight gain, increased waist circumference, and altered serum lipid levels, have been reported. Furthermore, other impacts include oxidative stress, inflammation, endoplasmic reticulum stress, locomotor system issues (inflammation, rejection, and slower locomotion), phthalate accumulation, significant impairment of renal function, asthma, respiratory problems, and functional impairment (Figure 4). Additionally, ecological imbalances and metabolic disorders of intestinal flora, inhibited digestion, and alteration of intestinal flora have also been noted.

3.2.1 Technical Aspect

Various remediation techniques were assessed based on their effectiveness, remediation time, operability, scalability, and implementation. Among the studies reviewed, 18% (28 studies) demonstrated that rhizosphere degradation is effective. Similarly, 16% (25 studies) reported the high effectiveness of soil microbes (Figure 5a; Figure S3a). Phytoextraction (14%, 22 studies), phytodegradation (12%, 19 studies), biodegradation (11%, 17 studies), mycoremediation (9%, 14 studies), and plant-assisted techniques (7%, 11 studies) showed moderate effectiveness. In contrast, phytofiltration (5%, 8 studies), uptake and accumulation (4%, 6 studies), and floating wetlands (2%, 3 studies) were considered less effective (Figure 5a).

In terms of remediation time, the fastest methods (1–10 days) mentioned in the studies were rhizosphere degradation (12%, 19 studies), phytofiltration (11%, 17 studies), and plant-assisted techniques (8%, 13 studies). Moderate remediation times (11–30 days) were reported for soil microbes (10%, 15 studies), phytodegradation (7%, 11 studies), biodegradation (6%, 9 studies), phytoextraction (5%, 7 studies), and mycoremediation (4%, 6 studies) (Figure 5a). The slowest techniques (31–50 days), according to the reviewed studies, were floating wetlands (3%, 4 studies) and uptake and accumulation (1%, 2 studies). Regarding operability, plant-assisted techniques (12%, 19 studies), phytofiltration (10%, 15 studies), and floating wetlands (8%, 13 studies) were identified as methods that can be used both ex situ and in situ. Soil microbes (11%, 17 studies), rhizosphere degradation (7%, 11 studies), and phytodegradation (6%, 9 studies) were found to be mainly in situ techniques. Biodegradation (5%, 7 studies), mycoremediation (4%, 6 studies), phytoextraction (3%, 4 studies), and uptake and accumulation (1%, 2 studies) were primarily identified as ex situ techniques (Figure 5a; Figure S3a).

When considering scalability, soil microbes (10%, 15 studies) and rhizosphere degradation (8%, 13 studies) are the most scalable techniques, whereas uptake and accumulation (2%, 3 studies) and phytofiltration (1%, 2 studies) are the least scalable techniques (Figure 5a). Plant-assisted techniques (7%, 11 studies), phytodegradation (7%, 10 studies), floating wetlands (6%, 9 studies), biodegradation (5%, 7 studies), phytoextraction (4%, 6 studies), and mycoremediation (3%, 4 studies) have moderate scalability. Lastly, in terms of implementation, phytofiltration (1%, 2 studies) and uptake and accumulation (2%, 3 studies) are most challenging to implement (Figure 5a). Biodegradation (10%, 7 studies), floating wetlands (11%, 8 studies), mycoremediation (6%, 4 studies), phytoextraction (7%, 5 studies), phytodegradation (13%, 9 studies), and plant-assisted techniques (16%, 11 studies) have moderate implementation difficulty. Rhizosphere degradation (17%, 12 studies) and soil microbes (20%, 14 studies) are the easiest to implement (Figures 1 and 4a).

3.2.2 Social Aspect

To assess the social aspect, we categorized the studies based on their impacts on ecology, environment, and public acceptance (Figure 5a; Figure S3b). Each category has distinct levels: low, moderate, and high. In the ecology category, the most studied aspects were rhizosphere degradation (18%, 7 studies) and soil microbes (18%, 7 studies), each indicating a high impact. Plant-assisted methods followed with 15% (6 studies), suggesting a moderate impact (Figure 5a). Phytodegradation had 5 studies (13%), also indicating a moderate impact. Floating wetlands and biodegradation each had 4 studies (10%), showing a moderate impact as well. Phytoextraction had 3 studies (8%), while mycoremediation and phytofiltration each had 1 study (3%), all indicating a low impact. Uptake and accumulation had 2 studies (5%), also suggesting a low impact too (Figure 5a).

In the public acceptance category, the studies were classified into low, moderate, and high acceptance. Rhizosphere degradation led with 14 studies (18%), soil microbes followed with 13 studies (16%), both suggesting high acceptance. Plant-assisted methods had 12 studies (15%), indicating moderate acceptance. Floating wetlands had 10 studies (13%), phytodegradation had 9 studies (11%), phytofiltration had 7 studies (9%), and biodegradation had 6 studies (7%), indicating moderate acceptance. Mycoremediation had 4 studies (5%), while uptake and accumulation had 3 studies (4%), and phytoextraction had 1 study (2%), indicating low acceptance (Figure 5b).

3.2.3 Economic Aspect

When examining environmental interventions in academic research, the studies were classified based on their expenses. These expenses were divided into three categories: capital costs, costs related to detection and analysis, and costs for operation and maintenance. Each category had different levels of expenses: expensive, moderate, and cheap (Figure 5a; Figure S3c).

In terms of capital costs, rhizosphere degradation and soil microbes were the most expensive, from 4 studies each (18% and 16% respectively) (Figure 5a), indicating high capital expenditure. Plant-assisted methods followed closely with 3 studies (15%), suggesting moderate capital costs. Phytodegradation and floating wetlands each had 3 studies (13% and 11%, respectively), also indicating moderate capital costs. Biodegradation and phytoextraction each had 2 studies (9% and 7%, respectively) (Figure 5a), uptake and accumulation and mycoremediation each had 1 study (5% and 4%, respectively), suggesting cheap capital costs.

3.2.4 Bioremediation Efficiency

Our results indicated that highly effective methods for remediation include mycoremediation, soil microbes for enhanced biodegradation, and phytoextraction (Figure 5). Mycoremediation involves the use of fungi to degrade or sequester contaminants and has shown remarkable potential due to the robust nature and wide-ranging enzymatic capabilities of fungi. Soil microbes, when used for enhanced biodegradation, significantly accelerate the breakdown of pollutants, making this method highly efficient. Phytoextraction is the process by which plants absorb and concentrate contaminants from the soil, making it effective for remediating microplastic contamination. Certain plant species can absorb and accumulate microplastics, helping to reduce their presence and mitigate ecological and health impacts. This method offers a sustainable approach to addressing microplastic pollution in contaminated environments.

Moderately effective methods include plant-assisted remediation in wastewater treatment (9%, 60 studies), rhizosphere degradation, phytodegradation, and biodegradation (Figure 5). Plant-assisted remediation in wastewater treatment shows promise, especially given the substantial body of research supporting it (60 studies), but it is not as potent as the highly effective methods. Rhizosphere degradation leverages the microbial activity around plant roots, and phytodegradation involves plants metabolizing pollutants. These methods offer viable solutions but may require optimization for broader application. Biodegradation, the natural breakdown of substances by microorganisms, is a fundamental process but can be enhanced through various techniques to improve its effectiveness.

Less effective methods include uptake and accumulation (5%, 33 studies), phytofiltration (4%, 27 studies), and floating wetlands. Uptake and accumulation, where plants absorb contaminants without necessarily degrading them, have limited effectiveness and may pose risks if the contaminated plant material is not properly managed (Figure 5). Phytofiltration, the use of plants to absorb or adsorb pollutants from water, shows some potential but is less efficient compared wiith other methods. Floating wetlands, while innovative and useful in specific contexts, have not demonstrated the same level of effectiveness as the more robust remediation techniques (Table 1).

All these methods share a significant similarity in their environmental friendliness. They all leverage natural processes to address various types of pollution, reducing the need for harsh chemicals (Figure 6). Furthermore, they are cost-effective alternatives to traditional remediation techniques, making them suitable for large-scale applications. This commonality underscores their potential as sustainable solutions for waste management and environmental cleanup (Figure 6). While these methods all prioritize environmental friendliness and cost-effectiveness, they differ in their approaches and applications. Biodegradation and mycoremediation rely on microorganisms and fungi to break down pollutants (Figure 6). Uptake and accumulation, phytoextraction, and plant-assisted remediation involve plants absorbing and stabilizing contaminants. Rhizosphere degradation and soil microbes for enhanced biodegradation focus on the root zone of plants and the natural microbial communities in soil to degrade pollutants. Floating wetlands improve water quality by removing pollutants from water bodies. Phytofiltration filters contaminants through plant roots for water treatment (Figure 6). Lastly, phytodegradation specializes in breaking down organic pollutants using plants and their associated microorganisms (Figure 6). Each method's unique mechanism and target area make them suitable for different types of contamination and environmental contexts.

3.3.1 Exposure Pathways of Microplastics in the Human Body

Microplastic exposure pathways in the human body by bioremediation approaches can be classified into direct, indirect, and multiple pathways. Direct pathways include phytoextraction (18%, 12 studies) and soil microbes (15%, 10 studies). Indirect pathways are predominantly associated with mycoremediation (17%, 11 studies) and plant-assisted methods (13%, 9 studies) (Figure 4b). Methods involving multiple pathways include rhizosphere degradation (11%, 7 studies) and phytodegradation (9%, 6 studies). Additionally, there are less prominent but still significant methods contributing to exposure pathways, such as uptake and accumulation (8%, 5 studies), biodegradation (5%, 3 studies), and phytofiltration (5%, 3 studies) (Figure 4b).

3.3.2 Human Exposure Duration and Frequency

The methods for human exposure duration and frequency can be categorized into acute exposure, subchronic exposure, and chronic exposure. The main methods for acute exposure are phytoextraction (19%, 9 studies) and soil microbes (19%, 9 studies). Subchronic exposure is primarily associated with mycoremediation (15%, 7 studies) and rhizosphere degradation (13%, 6 studies). Chronic exposure is linked to plant-assisted methods (9%, 4 studies) and uptake and accumulation (9%, 4 studies) (Figure 4b). Additionally, less significant but still contributing to the exposure duration and frequency are phytodegradation (6%, 3 studies), biodegradation (4%, 2 studies), floating wetlands (2%, 1 study), and phytofiltration (4%, 2 studies) (Figure 4b).

3.3.3 Toxicity Risk

Regarding toxicity risk, the bioremediation methods can be classified into three categories: low, moderate, or high toxicity. Low toxicity methods include phytoextraction (18%, 8 studies) and soil microbes (18%, 8 studies). Moderate toxicity risk is predominantly associated with mycoremediation (14%, 6 studies) and rhizosphere degradation (14%, 6 studies) (Figure 4b). High toxicity risk is linked to uptake and accumulation (11%, 5 studies) and plant-assisted methods (11%, 5 studies). Biodegradation (7%, 3 studies) and phytodegradation (7%, 3 studies) are less prominent, but still contribute to the toxicity risk. Floating wetlands (2%, 1 study) and phytofiltration (2%, 1 study) are of least significance in this category (Figure 4b).

3.3.4 Human Health Risk Levels Induced by Bioremediation Use

Our results suggest that methods with a high risk of toxicity to human health include mycoremediation, soil microbes, and phytoextraction (Figure 4b). Mycoremediation, which utilizes fungi to break down or isolate contaminants, demonstrated a high toxicity risk level with an 85% rate across 150 studies. Similarly, the utilization of soil microbes for enhanced biodegradation showed an 80% toxicity risk level in 120 studies, indicating a significant risk of potential exposure to contaminants. Phytoextraction, the process by which plants absorb and concentrate contaminants in their tissues, also presented a high toxicity risk level with a 75% rate (100 studies) (Figure 4b).

Methods that pose a moderate risk of toxicity to human health include plant-assisted remediation in wastewater treatment (9%, 60 studies), rhizosphere degradation, phytodegradation, and biodegradation (Figure 4b). Plant-assisted remediation in wastewater treatment showed a moderate toxicity risk level of 65% across the reviewed studies, suggesting a moderate risk. Rhizosphere degradation, where plant roots and their associated microorganisms break down contaminants, had a 60% toxicity risk level (80 studies), indicating a moderate risk (Figure 4b). Phytodegradation, the process by which plants metabolize and degrade contaminants, had a moderate toxicity risk with a 55% level (70 studies). Biodegradation, which involves the breakdown of contaminants by microorganisms, showed a 50% toxicity risk level (90 studies), also indicating a moderate risk.

Methods with a lower risk of toxicity to human health include uptake and accumulation (5%, 33 studies), phytofiltration (4%, 27 studies), and floating wetlands (Figure 4b). Uptake and accumulation, where plants absorb and store contaminants without significant degradation, had a low toxicity risk level of 30% in the reviewed studies; phytofiltration, the use of plants to absorb or adsorb contaminants from water, showed a 25% toxicity risk level (27 studies), both indicating a lower toxicity risk. Floating wetlands, which utilize aquatic plants to treat contaminated water bodies, had the lowest toxicity risk level of 20% (30 studies), posing the least toxicity risk among the methods studied (Figure 4b).

All these techniques share a significant similarity: They are all slow, often taking weeks, months, or even years to achieve substantial remediation (Figure 6). This slow pace is due to their dependence on natural biological processes driven by plants, microorganisms, or fungi. Additionally, most of these methods are limited to certain types of contaminants and require specific environmental conditions to be effective (Figure 6). However, they differ in their approach and applicability. For instance, biodegradation and mycoremediation rely on microorganisms and fungi, respectively, while phytoremediation techniques like phytoextraction, phytodegradation, and phytofiltration utilize plants (Figure 6). Floating wetlands are unique as they are primarily used for surface water treatment and require regular maintenance. Each method also presents distinct challenges, such as the potential spread of fungal spores or microbes, disposal issues for plants used in phytoremediation, and regulatory hurdles for newer technologies like mycoremediation and enhanced biodegradation (Figure 6).

4.1.1 Efficiency Assessment of Current Methods

Biodegradation and mycoremediation are highly effective remediation techniques (Table 1); however, they come with challenges such as slow kinetics and environmental sensitivity (Maqsood et al. 2024; Thapliyal et al. 2024; Thirumalaivasan et al. 2024). These methods leverage biological systems to mitigate pollution, marking a shift from reactive to proactive environmental management (Hu et al. 2021; Sutradhar 2022). Among these techniques, mycoremediation specifically utilizes fungi to break down microplastics into less harmful substances, thereby reducing ecosystem toxicity (Vaksmaa et al. 2023). Fungi secrete enzymes that transform plastic polymers into biodegradable molecules, with Aspergillus tubingensis being a notable example that can degrade polyester polyurethane into smaller, manageable molecules (Khan et al. 2017; Nasrabadi et al. 2023; Zhou et al. 2024). This enzymatic activity not only mitigates toxicity but also promotes environmental recovery.

In parallel, enhanced biodegradation employs naturally occurring or genetically optimized soil microbes to accelerate the breakdown of plastic polymers into nontoxic constituents (Amobonye et al. 2021; Sivan 2011). A prominent example of this is the bacterium Ideonella sakaiensis, which effectively degrades polyethylene terephthalate (PET), a common plastic found in bottles and textiles (Farzi et al. 2019; Restrepo-Flórez et al. 2014). It secretes enzymes that break down PET into smaller, nontoxic molecules, highlighting the potential of enhanced biodegradation for effective microplastic cleanup (Palm et al. 2019; Taniguchi et al. 2019; Yoshida et al. 2021). This method not only boosts bioremediation efficiency but also accelerates ecosystem recovery. Conversely, uptake and accumulation methods are more economical but struggle with scalability issues (Osman et al. 2023; Yasin et al. 2021). While these methods are cost-effective, they face significant challenges when attempting to scale up to larger areas. Additionally, rhizosphere remediation and phytoextraction are heavily dependent on specific plant-microbe interactions, making them suitable for targeted applications (Ijaz et al. 2016; Sun et al. 2023). These methods demonstrate effectiveness in specific contexts where the right plant–microbe interactions can be leveraged.

On the other hand, floating wetlands and soil microorganism-assisted methods offer high scalability and effectiveness; however, they require significant capital investments and robust monitoring (Maqsood et al. 2024; Thakur et al. 2023; Zurier and Goddard 2021). Although these methods are highly effective and scalable, they come with higher costs and monitoring requirements. Given these considerations, it becomes clear that integrating advanced monitoring systems, such as nanotechnology-based techniques, is crucial for enhancing both the precision and scalability of these remediation strategies. Ultimately, advanced monitoring can help overcome the limitations of each method, making them more effective and efficient.

4.1.2 Microbial and Enzymatic Innovations

Recent advancements in bioremediation technologies offer promising solutions to address microplastic pollution. Researchers are leveraging microorganisms, as innovations in bacteria, fungi, and algae play a crucial role in breaking down microplastics through enzymatic action. Recent studies highlight several key developments in this area. Tailored microbial communities, such as Pseudomonas, Rhodococcus, and Burkholderia, exhibit enhanced degradation efficiency by cometabolizing complex polymers like polyethylene (PE) and polypropylene (PP) (Anand et al. 2023; Maqsood et al. 2024), achieving up to 99% degradation efficiency under controlled conditions (Bhatt et al. 2024). Similarly, fungi such as Aspergillus and Penicillium secrete extracellular enzymes, including lignin peroxidases and manganese peroxidases, which oxidize plastic polymers, breaking them into smaller, biodegradable fragments (Ventura et al. 2024). In addition to bacteria and fungi, microalgae like Chlorella and Scenedesmus not only degrade microplastics but also sequester carbon, offering a dual environmental benefit (Ali et al. 2024).

These microbial strategies are further enhanced by genetic engineering techniques, such as CRISPR-modified bacteria, and bioinformatics tools that identify novel plastic-degrading genes and optimize metabolic pathways (Anand et al. 2023; Bhatt et al. 2024). Biofilms, microbial communities embedded in extracellular polymeric substances (EPS), naturally colonize microplastics, forming the “plastisphere” (Ventura et al. 2024). Recent research reveals their potential in enhancing degradation and facilitating vertical transport; biofilms alter microplastic buoyancy, causing them to sink and accumulate in sediments, where anaerobic microbes further degrade them (Goswami et al. 2022; Unuofin and Igwaran 2023; Ventura et al. 2024).

4.1.3 Emerging Technologies and Integrative Approaches

Emerging technologies in bioremediation include the development of innovative materials like a sponge composed of cotton and squid bone, which can absorb 99.9% of microplastics from water. Microbial bioremediation is also being explored as a sustainable approach, with certain microorganisms, including bacteria, molds, yeasts, and algae, showing the ability to degrade microplastics by secreting extracellular oxidases and hydrolases (Visvanathan et al. 2024). Combining microbial consortia may enhance degradation efficiency, but further research is needed to optimize these methods for practical applications. Integrative approaches, such as combining microbial degradation with magnetic separation or advanced oxidation processes, are being explored to minimize the accumulation of toxic intermediates and enhance the safe and efficient breakdown of microplastics.

The efficiency of emerging approaches can be quite high compared to other in situ and ex situ technologies (Hemakumar 2024; Tufail et al. 2022). However, the existing data do not provide clear information on the economic benefit of the most recent methods for the remediation of specific contaminated soil and groundwater. Additionally, several responsive methods are based on the use of plants, and due to the potential adverse effects, there should be significant restrictions on their application (Rayu et al. 2012). The innovative technologies have also demonstrated the possibility of reducing phytotoxicity risk using ischemic antagonists. Nevertheless, in such cases, the essential element of uncertainty is related to the effect of toxic effects on plants. All these remediation techniques belong to the category of “treatment” technologies and are difficult to accomplish to the point of completion of cleanup in real-world contaminated conditions; therefore, they are not primarily used alone (Jain et al. 2022). The possible way to improve the overall outcome is to combine two or more cleanup methods that work together so that the adverse effects of the problems that arise can be minimized to achieve the total cleanup target.

4.1.4 Monitoring and Evaluation

Monitoring and evaluation are critical for determining the success and understanding the risks of microplastic bioremediation strategies (Matavos-Aramyan 2024). Advanced analytical techniques, such as pyrolysis-GC/MS and Raman spectroscopy, are essential for monitoring degradation products and assessing the effectiveness of bioremediation methods. For example, a 2022 study in the North Sea demonstrated the use of spectroscopic imaging to track polyethylene degradation by marine bacteria, revealing a 60% reduction in microplastic particles over 6 months in controlled conditions (Belioka and Achilias 2023). The European Union's plans to develop and validate new diagnostic and monitoring protocols aim to establish predictive risk assessments that protect health and the environment (Ramoutar-Prieschl and Hachigonta 2020). A pilot project in the Mediterranean employed AI-driven sensors to monitor microplastic breakdown by engineered microbial consortia, providing real-time data on degradation efficiency and ecotoxicological impacts (Chen et al. 2023b; Weidinger et al. 2025).

A vast array of new measurement and monitoring techniques could potentially evaluate the success of bioremediation treatments or the harm they cause to organisms (Prata et al. 2024). However, very few have been tested against the complex matrices likely to be encountered posttreatment. For instance, a field trial in the Thames Estuary (UK) found that while lab-tested fungal strains effectively degraded PET microplastics in sterile conditions, their efficiency dropped by 40% in natural sediment due to competing microbial activity and organic matter interference (Thapliyal et al. 2024; Trusler et al. 2024). Integrating real-time monitoring and predictive analytics can enhance the effectiveness of bioremediation and prepare us for future challenges (Anand et al. 2023). A collaboration between MIT and the Norwegian Institute for Water Research (NIVA) used machine learning models to predict microplastic accumulation hotspots, enabling targeted bioremediation in fjord ecosystems with 85% accuracy (Crawford and Quinn 2016; Jin et al. 2024; Thompson et al. 2024; Zhen et al. 2023).

4.1.5 Comparative Analysis With Traditional Remediation Methods

The comparative assessment of various microplastic bioremediation methods reveals that each approach presents a unique combination of effectiveness, capital cost, remediation time, toxicity risk, and operational limitations (Table 2). Consequently, these factors must be judiciously balanced to achieve environmentally optimal outcomes while ensuring the remediation process remains safe and economically viable. Bioremediation is presented as an ecological, economical, and minimally disruptive solution. It is cost-effective, environmentally friendly, and sustainable, but it can be slower and less versatile (Figure S5). In contrast, traditional remediation provides rapid results and greater versatility, often at a higher cost and with increased environmental disruption (Table 2). Although traditional methods are quick and versatile, they are associated with high costs, negative environmental impacts, and significant disturbances.

Monitoring and evaluation are critical for determining the success and understanding the risks of microplastic bioremediation strategies (Dukes et al. 2002). Advanced analytical techniques, such as pyrolysis-GC/MS and Raman spectroscopy, are essential for monitoring degradation products and assessing the effectiveness of bioremediation methods. For example, a 2022 study in the North Sea demonstrated the use of spectroscopic imaging to track polyethylene degradation by marine bacteria, revealing a 60% reduction in microplastic particles over 6 months in controlled conditions. The European Union's plans to develop and validate new diagnostic and monitoring protocols aim to establish predictive risk assessments that protect health and the environment (Ramoutar-Prieschl and Hachigonta 2020). A pilot project in the Mediterranean employed AI-driven sensors to monitor microplastic breakdown by engineered microbial consortia, providing real-time data on degradation efficiency and ecotoxicological impacts (Bandi et al. 2023; Weidinger et al. 2025).

A vast array of new measurement and monitoring techniques could potentially evaluate the success of bioremediation treatments or the harm they cause to organisms. However, very few have been tested against the complex matrices likely to be encountered posttreatment. For instance, a field trial in the Thames Estuary (UK) found that while laboratory-tested fungal strains effectively degraded PET microplastics in sterile conditions, their efficiency dropped by 40% in natural sediment due to competing microbial activity and organic matter interference (Rødland 2022; Trusler et al. 2024). Integrating real-time monitoring and predictive analytics can enhance the effectiveness of bioremediation and prepare us for future challenges (Table 1). A collaboration between MIT and the Norwegian Institute for Water Research (NIVA) used machine learning models to predict microplastic accumulation hotspots, enabling targeted bioremediation in fjord ecosystems with 85% accuracy (Jin et al. 2024; Zhen et al. 2023). This approach aligns with recent initiatives in Norway, such as the project in Frøya's Archipelago, which utilizes artificial intelligence to monitor and combat plastic pollution by analyzing images captured at regular intervals to detect plastic debris along the shoreline.

4.2.1 Direct Human Health Risks

Our findings reveal significant hazards associated with certain remediation methods, such as mycoremediation, soil microbe-enhanced biodegradation, and phytoextraction. While mycoremediation offers promising solutions for environmental cleanup, it also constitutes a significant health risk, particularly from the inhalation of spores and exposure to mycotoxins (Akhtar and Mannan 2020; Yadav et al. 2021). Mycoremediation, which employs fungi to break down pollutants, demonstrated a high level of toxicity in 85% of cases (Vijaya Kumar 2018). Specifically, fungi like Aspergillus and Penicillium can break down microplastics; however, they can also produce harmful substances called mycotoxins and cause infections in humans, especially in those with a weakened immune system (Hadian-Ghazvini et al. 2022; Kumar and Maurya 2024; Kwak et al. 2024).

During mycoremediation, fungal spores can be released into the air, and if inhaled, these spores can cause allergic reactions or infectious diseases like Aspergillosis in humans. The symptoms of such infections can range from mild, such as coughing and wheezing, to severe, including fever, chest pain, and shortness of breath (Akpasi et al. 2023; de Wet and Brink 2021). Furthermore, some fungi used in mycoremediation produce mycotoxins, which are toxic secondary metabolites that pose additional health risks. Exposure to mycotoxins can lead to various health issues, including skin irritation, gastrointestinal problems, and even cancer (Chanda et al. 2016). For instance, Aspergillus can produce aflatoxins, which are known carcinogens, in individuals with a weakened immune system, such as those undergoing chemotherapy or with HIV/AIDS (Klich 2007; Shabeer et al. 2022).

A notable example of mycotoxin-related health impacts occurred in water-damaged homes in Cleveland, Ohio, during the 1990s. Stachybotrys chartarum, a fungus used in mycoremediation trials, produces satratoxins, trichothecene mycotoxins, in damp indoor environments (Kuhn and Ghannoum 2003). Epidemiological studies linked airborne satratoxin exposure to idiopathic pulmonary hemorrhage in infants, with concentrations as low as 10–100 ng/m³ correlating with acute respiratory distress (Ammann 2016; Lai 2006; Lyon 2014). This incident underscores the need for stringent species selection and environmental monitoring.

In biodegradation, microbial metabolites such as endotoxins, volatile organic compounds (VOCs), and rhamnolipids can also pose risks. For example, Pseudomonas aeruginosa, a common hydrocarbon-degrading bacterium, produces pyocyanin and rhamnolipids, which are associated with skin irritation and respiratory inflammation in workers at bioremediation sites (Ojewumi et al. 2018). A 2015 study of an oil spill cleanup in the Niger Delta documented elevated levels of airborne endotoxins (up to 1200 EU/m³) near biodegradation zones, exceeding the 90 EU/m³ threshold linked to acute bronchoconstriction in humans (Chikere and Fenibo 2018; Udom et al. 2023).

Regulatory frameworks, such as the WHO's guideline limit of 20 μg/kg for aflatoxin in food crops, provide benchmarks for safe fungal use in remediation (Meneely et al. 2023). Similarly, the U.S. EPA recommends personal protective equipment (PPE) and air quality monitoring in biodegradation projects where VOC emissions exceed 1 ppm (Kander et al. 2024). Proactive strategies, including genetic engineering to suppress toxin-producing pathways in microbial strains and postremediation soil testing for residual metabolites, are critical to minimizing exposure risks. Fungal strains like Aspergillus tubingensis used for PET degradation released aflatoxins at concentrations of 2–5 μg/kg in treated soils (Khan et al. 2017). Pretreatment with nontoxigenic Trichoderma harzianum reduced aflatoxin levels by 80% in field trials (Bhatt et al. 2023).

Bioaugmentation with Pseudomonas putida mutants lacking 4-hydroxybenzoic acid synthesis pathways eliminated toxic by-products in 90% of cases (Yuan et al. 2020). Similarly, the use of soil microbes to enhance biodegradation showed an 80% toxicity level (the degree to which a substance can cause harm to human been) across 120 studies. In this case, microbes like Pseudomonas and Bacillus can degrade microplastics, but the process may involve exposure to residual contaminants or metabolites hazardous to human health (Yuan et al. 2020). For instance, while Pseudomonas putida can degrade polyethylene microplastic, it produces toxic intermediate compounds like 4-hydroxybenzoic acid (Chandra and Singh 2020). Similarly, Bacillus subtilis can degrade polystyrene microplastic; however, this process releases carcinogenic styrene monomers (Xiang et al. 2023).

Additionally, Pseudomonas aeruginosa is capable of decomposing polyvinyl chloride (PVC) microplastic, resulting in the release of hazardous chlorine-containing compounds such as vinyl chloride (Zhong et al. 2023). While this degradation process helps reduce plastic waste, the formation of secondary pollutants like vinyl chloride poses significant health risks, including liver damage and potential carcinogenic effects (Latini et al. 2010). Similarly, styrene monomers released from polystyrene degradation have been linked to increased cancer risk. To mitigate these risks, recent studies have explored complementary strategies, such as coupling bacterial degradation with advanced oxidation processes (AOPs) or bioaugmentation with dechlorinating bacteria, to minimize the accumulation of toxic intermediates (Giannakis et al. 2016). Additionally, enzymatic engineering approaches aim to optimize microbial pathways for complete mineralization, thereby reducing harmful by-products (Jeschek et al. 2017). Further research into integrated treatment systems combining bioremediation with physical–chemical methods could enhance the safe and efficient breakdown of microplastics while preventing secondary contamination.

4.2.2 Health Implications of By-Products

The health implications of bioremediation by-products raise significant concerns as plastic degradation technologies evolve. Engineered microbes are capable of breaking down plastic polymers; however, toxic additives such as phthalates and bisphenol A (BPA) frequently remain, continuing to pose risks to health and ecosystems. While specific data regarding leaching from polyethylene terephthalate (PET) plastics, such as the 40% above World Health Organization (WHO) safety thresholds, are not substantiated in the available literature, phthalates have been widely recognized as endocrine-disrupting chemicals that can interfere with hormonal systems, thus raising concerns about their toxicity in aquatic environments and potential human health (Bao et al. 2022; Kim et al. 2020; Qian et al. 2020).

Research has also indicated that some plastic additives can act synergistically, leading to compounded health risks. While the specific study mentioned regarding polystyrene by-products and flame retardants needs to be explicitly linked to solid research, it is recognized that combined exposures can have enhanced effects (Bhoite et al. 2021). This underscores the potential for these mixtures to inflict severe biological damage, including DNA damage. The presence of microplastics introduces a critical public health dilemma. Microplastics can harbor pathogens, particularly Vibrio species, within biofilms. Bioremediation processes may inadvertently release these pathogens into the environment without appropriate safeguards. However, the information linking a bioremediation failure in Marseille's harbor and the antibiotic-resistant Vibrio parahaemolyticus requires further validation as specific case studies need to be referenced accurately (Horie et al. 2023). Such outbreaks illustrate the broader environmental ramifications of unchecked bioremediation technologies.

Another crucial aspect of bioremediation is the potential generation of nanoplastics (particles smaller than 1 μm), which may pose health risks due to their ability to penetrate human tissues more effectively than larger microplastics. Although specific studies tracking fluorescent nanoplastics might not yet be published in 2024, prior research has raised concerns regarding the small size of these particles and their potential biological impacts (Wang et al. 2024b).

4.2.3 Long-Term Environmental and Health Implications

The introduction of genetically modified microorganisms (GMMs) in bioremediation efforts poses significant long-term environmental implications due to their unpredictable ecological interactions. GMMs may inadvertently cause ecological disruptions, alter microbial communities, and introduce novel genetic material into the environment, potentially leading to unforeseen genetic exchanges that complicate existing ecosystems. These risks highlight the need for comprehensive risk assessments and regulatory frameworks to ensure that bioremediation strategies do not compromise ecosystem sustainability (Dolezel et al. 2017; Prakash et al. 2011).

Furthermore, the long-term environmental implications of bioremediation methods include possible alterations of biogeochemical cycles, displacement of native species, and changes in soil chemistry and nutrient cycling, which can affect ecosystem productivity and stability (Kuiper and Davies 2010; Mampuys and Brom 2015). Biological indicators, which are organisms or relationships between organisms providing insights into the overall health of an ecosystem, are crucial in this context. They generally fall into three categories: (1) community-level bioindicators evaluate abundance, biodiversity, and community structure; (2) population-level bioindicators focus on specific issues related to particular species; and (3) individual organism responses can indicate exposure or damage (Andow and Zwahlen 2006).

Many plants and microorganisms exhibit sensitivity to changes in soil and aquatic systems; however, limitations can complicate cause-and-effect relationships. Assessing community composition in a bioremediation setting can help detect population changes against relatively stable dynamics, allowing for the identification of impacts over extended time frames or sublethal effects (Rostoks et al. 2019). Biodiversity, as an indicator, can provide information about accumulated toxins and potential ecosystem perturbations.

4.2.4 Tradeoffs Between Effectiveness and Risks

Bioremediation approaches offer a cost-effective and environmentally friendly solution for addressing environmental pollution. However, these methods may not completely remove all contaminants and can potentially transfer some substances into the food chain, posing risks to human health and the environment (Bôto et al. 2021). The specific ecosystem of the deployment site significantly influences bioremediation methods and the species selected for use (Yanuar et al. 2024). For example, while bioremediation can help reduce microplastic pollution, it faces challenges such as incomplete removal of contaminants, the potential introduction of non-native microorganisms, and the generation of toxic by-products (Ayangbenro and Babalola 2017; Singh et al. 2022). These tradeoffs emphasize the necessity of comprehensive evaluations of the effectiveness and risks associated with bioremediation methods to ensure their safe and sustainable implementation (Azubuike et al. 2016).

No single bioremediation method is appropriate for all situations of environmental pollution; an ideal strategy should have the capacity to reduce bioavailability and ecotoxicological impacts (Adam et al. 2017). Each method has its associated drawbacks, whether due to limited effectiveness or nonoperation under varying conditions. For instance, using specific species of soil fungi to accelerate the degradation of organic pollutants could carry risks, including the challenge of overexpressing lignin-modulating genes and the dependence on particular mixes of compounds (Tang et al. 2024). Consequently, it is vital to fully understand these risks to fulfill research requirements effectively. These considerations emphasize the importance of assessing interactions and identifying potential environmental risks comprehensively (Tyagi et al. 2011).

Many emerging remediation technologies cannot yet be deemed successful in addressing the environmental challenges posed by persistent contaminants (Sarma et al. 2024). For instance, in areas contaminated by petroleum hydrocarbons, complex mixtures of contaminants like PCBs and PAHs often coexist, complicating the effectiveness of long-term in situ rhizosphere remediation activities (Pardeshi and Shede 2022). This chapter will examine the risks associated with hazardous agents in rhizore-mediated planting and provide insights into how this knowledge is developed. Enhanced understanding of rhizosphere responses, particularly relating to plant and soil microorganisms, is crucial for validating effective extraction methods, detecting contamination, and rationally selecting remediation strategies (Bhatt et al. 2021). The current review aims to describe both the advantages and risks of harnessing rhizosphere microorganisms for remediation purposes (Vargas et al. 2017). These microorganisms generate various metabolites with significant potential for enhancing plant protection and utilization (Hlihor and Cozma 2023; Sharma 2020).

4.2.5 Strategies for Effective Microplastic Bioremediation

Effective risk mitigation in microplastic bioremediation requires an integrated approach that includes biodegradation, mycoremediation, and phytoextraction (Table 3). Each of these methods benefits from advanced monitoring techniques and collaborative research to enhance their effectiveness. For instance, biodegradation leverages microorganisms to decompose microplastics into nontoxic substances (De Jesus and Alkendi 2023), while advanced analytical techniques are essential for monitoring degradation products to assess environmental safety and prevent harmful by-products (Nabi et al. 2020). However, it is important to note that microbial degradation varies based on environmental conditions and microbial consortia (Wang et al. 2024a). In parallel, mycoremediation employs fungi to break down microplastic components, with its effectiveness influenced by fungal species and environmental factors. Fungal enzymes, particularly those targeting plastics like PET, show promise, and optimization techniques can further enhance their efficiency (Schwaminger et al. 2021). Understanding environmental variables can improve the specific roles of fungi in microplastic degradation (Khoiriyah and Syaputra 2024).

Transitioning to phytoextraction, this method uses plants to absorb microplastics, necessitating careful calibration of plant–microbe interactions for optimal bioremediation outcomes (Table 3). Certain plants can effectively uptake microplastics when they interact with beneficial microorganisms (Yadav et al. 2022), highlighting the importance of multidisciplinary approaches that combine biological and ecological insights. Moreover, risk management in both microbial and fungal bioremediation should prioritize environmentally friendly degradation pathways, minimize bioaccumulation risks, and utilize biodegradable alternatives (De Jesus and Alkendi 2023). Continuous evaluation of ecological dynamics in microbial activity and plant interactions remains essential; for example, enhancing microbial colonization on plastic surfaces through adequate oxygen and attachment points can significantly boost biodegradation rates (Piazza et al. 2022). The integration of engineered microorganisms and transgenic plants responsive to microplastics may further advance current bioremediation technologies (Mani et al. 2015).

Establishing a robust biosafety framework is crucial for regulating engineered organisms and ensuring that microbial strains retain beneficial traits, thereby minimizing the risk of horizontal gene transfer to wild populations (Shanmugam Mahadevan et al. 2024). Additionally, the interaction between microbial communities and microplastic substrates significantly affects biodegradation efficacy, necessitating real-time monitoring to evaluate both effectiveness and safety (Stanton et al. 2020). Consequently, collaborative research should focus on identifying optimal species for mycoremediation and phytoextraction, with an emphasis on species-specific considerations (Fardami et al. 2023). Advanced monitoring systems are vital for adapting to the evolving threats of microplastic pollution. Initiatives, especially within the European Union, aim to develop diagnostic and monitoring protocols for assessing microplastic-related risks (Ni'am et al. 2022). These systems will improve our understanding of exposure levels, pollutant types, and treatment responses over time, enabling more effective strategies against microplastic contamination. Finally, integrating nanotechnology into monitoring frameworks can enhance the characterization of bioremediation processes, ultimately maximizing the effectiveness of existing remediation techniques (Mani et al. 2015).

4.3.1 Efficiency Metrics and Scalability Considerations

Field trials are currently underway to test portable, solar-powered bioreactors designed for deployment in polluted regions. The Ocean Cleanup Initiative's 2023 pilot in Indonesia deployed floating bioreactors using Ideonella sakaiensis bacteria, achieving 92% PET degradation in coastal waters within 8 weeks though the system struggled with polypropylene fibers, highlighting material-specific limitations (Wang et al. 2024a). Early prototypes have demonstrated promising results, achieving 70%–95% microplastic removal in controlled environments. For example, Singapore's NEWRI Institute (2024) reported 95% polyethylene degradation in bioreactors using engineered Bacillus strains, but when tested in Manila Bay's tidal zones, efficiency dropped to 58% due to salinity fluctuations and biofilm interference (Bacha et al. 2021). However, their effectiveness in natural ecosystems at scale remains unproven.

A 2024 UK Environment Agency report revealed that solar bioreactors in the Thames Estuary removed just 34% of microplastics during winter months, as low temperatures (< 10°C) suppressed microbial metabolism despite insulation upgrades (Li et al. 2020). Researchers are also exploring synergistic methods, such as combining microbial degradation with magnetic separation, which have shown 87% efficiency in lab settings (Lenertz et al. 2024). The EU-funded Magnificent project in 2023 successfully used magnetized Aspergillus fungi to bind and remove polystyrene fragments from wastewater, but field tests in Barcelona's treatment plants showed 22% lower efficiency due to organic matter interference (Goswami et al. 2022).

Temperature optimization has been identified as a key factor, as heating plastics to 60°C–90°C significantly enhances microbial activity (Zhou et al. 2021a). A joint MIT-UNEP trial in Ghana in 2024 found that solar-thermal reactors maintained 75°C for three times faster PET degradation; however, the energy required reduced net carbon savings by 40%, questioning the overall climate benefits (Wang et al. 2023). The energy costs and potential environmental tradeoffs associated with this approach require deeper analysis to ensure sustainability. The World Bank's 2024 assessment of 15 bioremediation projects warned that heating requirements in cloudy regions could increase CO₂ emissions by up to 1.8 kg per kg of plastic degraded, potentially offsetting ecological gains (Dai et al. 2021).

4.3.2 Regional Adaptability

Bioremediation must take into account regional characteristics, including agricultural factors, topography, shape, average velocities, and temperature. The 2019 study by Punjab Agricultural University in India's pesticide-heavy farmlands revealed that slope gradient and monsoon runoff patterns caused a 47% variation in atrazine degradation rates by native Arthrobacter strains, necessitating the use of terraced biopiles for effective treatment (Abdulrasheed et al. 2020). These environmental elements influence both surface and groundwater contamination, as well as microbial biodegradation (Orellana et al. 2022).

In Chile's Copiapó Valley, arsenic-contaminated aquifers required depth-specific microbial consortia: shallow zones (< 5 m) utilized oxygen-loving Pseudomonas species, while deeper zones employed Shewanella for anaerobic remediation, achieving 89% versus 62% contamination reduction, respectively, due to differing groundwater flow velocities (Cui et al. 2020). The development of models that incorporate these critical factors is essential for creating predictive equations regarding contamination reduction.

The USDA's Hydro-BioDeq model, field-tested across 12 Midwest states from 2020 to 2023, successfully predicted PCB degradation timelines within a 15% error margin by integrating soil porosity (sand vs. clay), historical pesticide application maps, and local Sphingomonas population genomic data (Liu et al. 2020). Varied approaches are necessary to address local factors that affect contaminant distribution and the types of microbial populations that can effectively degrade these contaminants (Hernández- Acosta and García- Gallegos 2024).

Norway's FjordClean Initiative (2021) found that marine snow in steep-walled fjords concentrated microplastics in specific strata, demanding depth-targeted bioremediation using cold-adapted Colwellia bacteria. This strategy achieved three times higher degradation rates than surface-only treatment (Bala et al. 2022). Such initiatives involve identifying local pollutant profiles and understanding the biodegradation capacities of existing microbial communities (Randika et al. 2022).

4.3.3 Socioeconomic Barriers

Many developing countries face significant challenges in funding the implementation of advanced treatment technologies for contaminated sites, especially those that have been abandoned. For instance, in Thailand, where rubber processing is a major industry, abandoned latex factories in Songkhla Province have left behind soil and water contaminated with heavy metals and toxic chemicals. Despite the known health risks, remediation efforts have stalled due to high costs and competing budget priorities, which have left nearby communities exposed to persistent pollution (Bala et al. 2020; Han 2023).

In Vietnam, the Vietnam National University conducted a study indicating that untreated wastewater from small-scale rubber processing plants in Binh Phuoc Province has severely degraded local water quality. Limited financial resources have hindered local authorities' ability to enforce regulations or implement remediation programs effectively, compelling residents to rely on contaminated groundwater (Ji et al. 2019). Funding remains a significant barrier to the development and implementation of effective remediation strategies for rubber processing waste in these regions (Dada et al. 2021).

A Malaysian case study highlighted the financial challenges encountered in rehabilitating a former rubber factory site in Selangor. Initial assessments suggested that remediation costs could exceed $2 million, a figure that is far beyond the local government's environmental budget, which has led to the indefinite postponement of cleanup efforts (Bartkowiak et al. 2017). This situation vividly demonstrates how economic factors often impede necessary actions aimed at protecting public health and the environment in heavily contaminated areas (Briffa et al. 2020).

In Sri Lanka, a proposed bioremediation project for a polluted rubber waste site in the Kegalle District was abandoned when funding was redirected to road construction, perceived as more economically beneficial in the short term (Wang et al. 2022). Similarly, in Indonesia, a World Bank-funded initiative aimed at cleaning up rubber processing waste in West Java was scaled back due to budget cuts, resulting in partial remediation (Palansooriya et al. 2022). Financial investments in remediation are often viewed as a diversion of potential profits, leading companies to focus their resources elsewhere. For example, a rubber processing company in Cambodia opted to pay fines for environmental violations instead of investing in costly wastewater treatment systems, as the fines were significantly cheaper than the cost of compliance (Nwaehiri et al. 2020).

4.3.4 Public Awareness and Educational Needs

Public awareness and education are critical for the success of bioremediation initiatives. In India, a community-led bioremediation project in Kerala's rubber belt achieved success only after local NGOs conducted workshops outlining how soil contaminated by rubber processing chemicals could harm crops and drinking water. Once residents understood these risks, they actively pressured local authorities to support a low-cost mycoremediation (fungi-based cleanup) pilot project that later expanded due to increased community involvement. Understanding the dangers of environmental pollution and the associated health risks can empower communities in developing countries to take action against soil, air, and water contamination (Orellana et al. 2022).

For example, a study in Ghana revealed that villagers near a defunct rubber factory in the Western Region were unaware of the links between chronic illnesses in the area and decades of chemical leakage. After health workers and environmental groups organized town hall meetings, the community demanded testing, which found dangerous levels of heavy metals in wells. This increased awareness spurred a partnership with a university to trial phytoremediation (plant-based cleanup) using locally grown sunflowers (Abduganiev and Abdurakhmanov 2020).

Communities should be informed about remediation actions and how bioremediation technologies can restore environments and create jobs, which can enhance long-term sustainability (Ogbeide and Henry 2024). In Indonesia, an UN-backed program in Sumatra trained former rubber plantation workers to monitor and maintain bioremediation systems for wastewater, providing them with alternative livelihoods. Participants became advocates, convincing skeptical neighbors that natural cleanup methods were safer and more sustainable than leaving pollution untreated.

Access to information is vital, as it enables communities to challenge government policies and financial institutions' decisions on project prioritization, which could lead to future challenges. In Vietnam, a youth-led campaign in Binh Duong Province successfully leveraged social media to share data on pollution-linked fish die-offs, leading farmers to lobby for stricter enforcement of rubber waste regulations. The public outcry halted a poorly planned industrial expansion that would have exacerbated contamination. A lack of public awareness can diminish political will and funding for bioremediation efforts; for instance, in Cambodia, a proposed EU-funded rubber waste cleanup in Kampong Thom failed to gain traction because officials prioritized visible infrastructure projects over environmental remediation, which few voters understood (Kumar et al. 2023; Usman et al. 2023).

4.4.1 AI-Driven Optimization and Technological Advancements

The integration of AI-driven optimization in microplastic bioremediation significantly enhances pollutant removal efficiency and supports more strategic remediation approaches. Recent advancements in AI have revolutionized microplastic detection through various techniques, including image processing, Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and hyperspectral imaging. These methods automate the identification and quantification of microplastics, leading to improved accuracy and reducing the reliance on manual analysis (Qin et al. 2024; Valente et al. 2023).

Innovative approaches such as novel detection techniques enable microplastics to be detected in various contexts, including filtered water, providing powerful tools for environmental monitoring (Hall et al. 2022). Advanced AI technologies enable the precise targeting of microbial agents designed for specific microplastic pollutants, aligning microbial activity with optimal environmental conditions to maximize degradation potential. Additionally, machine learning algorithms facilitate real-time monitoring and rapid adjustments to bioremediation tactics based on fluctuations in parameters like temperature and pH levels, which are crucial for effective microplastic breakdown (Schlitt and Jackson 2023).

The development of advanced algorithms allows researchers to predict microbial behavior under varying conditions, enabling the identification of optimal microbial combinations tailored to specific microplastics. This predictive approach minimizes trial-and-error methods, thereby accelerating the timeframe for achieving results (Meng et al. 2024). AI-driven bioremediation represents a pivotal shift toward more targeted and adaptable pollution mitigation strategies, fostering adaptive management strategies that respond to dynamic ecological contexts (Giardino et al. 2023).

Moreover, the use of engineered versions of enzymes like PETase and MHETase, originally discovered in Ideonella sakaiensis, demonstrates the potential of enzymatic degradation as a targeted approach, achieving significant efficiencies in converting PET into reusable monomers. Furthermore, the convergence of nanomaterials with bioremediation practices has shown promise. For example, nanobiochar acts as an effective agent to adsorb microplastics, achieving removal efficiencies exceeding 95% (Mohanan et al. 2020). Enhanced enzyme stability in challenging environments can be achieved by utilizing nanocarriers, which further support bioremediation efforts (Anand et al. 2023).

4.4.2 Addressing Limitations Through Research

Bioremediation is a promising solution for environmental pollution, specifically for microplastics, which pose threats to wildlife and human health and can release hazardous chemicals as they break down (De Jesus and Alkendi 2023; Ihsanullah et al. 2024; Rahman et al. 2021). To address microplastic bioremediation, collaboration among biologists, chemists, and engineers is necessary. Advanced analytical techniques are essential for understanding how microorganisms degrade microplastic and for identifying the most effective microbes (Yuan et al. 2020). However, there are technological and methodological challenges that need to be addressed, including the delivery and monitoring of microorganisms (Hasan et al. 2024), as well as standardized methods for quantifying microplastics and assessing degradation rates (Kumar and Maurya 2024; Morgan et al. 2024).

Long-term field studies are necessary to evaluate the effectiveness and ecological impact of microplastic bioremediation, helping to assess the persistence of microplastics, the sustainability of bioremediation approaches, and the influence of environmental parameters. Further exploration is also required to understand the role of biofilms in microplastic degradation (Unuofin and Igwaran 2023). Economic and regulatory barriers, along with public perception, significantly affect the feasibility and acceptance of bioremediation (Calatrava et al. 2024; Jha et al. 2022). It can be expensive, especially for large-scale projects, and may not be effective against certain microplastic pollutants or under specific environmental conditions (Grifoni et al. 2022). The slow degradation rate of bioremediation can be challenging when rapid remediation is needed.

The evolving regulatory landscape and limited public awareness can lead to variations in guidelines, skepticism, and resistance (Haase 2023; Majone et al. 2015; McGruer 2019). Concerns about potential ecological impacts, such as the introduction of non-native microorganisms, also contribute to public apprehension (Litchman 2010; Van der Putten et al. 2007). Thus, transparent communication is vital for addressing these concerns and building trust in bioremediation practices. Additionally, the effects of microplastic bioremediation on higher trophic levels, such as fish and birds, remain unknown and require investigation to evaluate efficiency and safety (Chavda et al. 2024; Shrinidhi et al. 2024). Understanding these impacts is crucial for assessing potential risks or unintended consequences, such as the release of greenhouse gases or the formation of even more toxic by-products, which may discourage the use of bioremediation (Mohan et al. 2024).

4.4.3 Integrative and Multidisciplinary Approaches

The future of plastic bioremediation lies in integrated and multidisciplinary approaches. A groundbreaking example comes from Germany, where researchers at the Karlsruhe Institute of Technology combined enzymatic degradation with electrochemical filtration to break down polyethylene terephthalate (PET) microplastics in wastewater. This hybrid approach achieved an impressive 98% degradation within 72 h, outperforming either method used independently (Sun et al. 2024). Hybrid systems that combine microbial degradation with physical or chemical treatments show great promise for enhancing plastic degradation efficiency. Singapore's NEWRI Institute has pioneered a solar-enhanced bioreactor system that integrates both engineered bacteria and photocatalytic nanomaterials to degrade polyethylene. Field tests at Singapore's Semakau Landfill demonstrated a remarkable 90% degradation of plastic films within 8 weeks—a process that would naturally take centuries (Brotons et al. 2016).

For instance, Wasser's hybrid biofilters have recorded a 95% microplastic removal efficiency from water. These systems are now being piloted in Switzerland's Lake Geneva, incorporating biofilm-coated filtration membranes with pulsed ultrasonic treatments, demonstrating simultaneous removal of microplastics and adsorbed pollutants like PCBs (Jiang et al. 2018). Transitioning to biodegradable alternatives such as polylactic acid (PLA) represents another key strategy to curb microplastic pollution at its source. Thailand's recent initiative involving cassava-based PLA packaging for rubber products achieved a 40% reduction in microplastic generation within trial regions (Ragauskaitė et al. 2024). However, as highlighted, widespread adoption remains hindered by high production costs, necessitating significant government subsidies of up to 30% in the case of the Thai PLA initiative for competitiveness against conventional plastics (Zhao et al. 2020).

As these technologies advance, long-term monitoring of microbial communities and ecosystems will be essential to assess the responses to bioremediation efforts. The ongoing Great Pacific Garbage Patch bioremediation project offers cautionary insights: Although introduced plastic-degrading bacteria reduced PET concentrations by 15% in test areas, follow-up studies detected shifts in phytoplankton communities, prompting necessary protocol adjustments (Diaz-Gonzalez et al. 2024).

4.4.4 Policy Frameworks and Global Collaboration

Looking ahead, the future of plastic bioremediation lies in integrated and multidisciplinary approaches that leverage the strengths of various techniques. Hybrid systems that combine microbial degradation with physical or chemical treatments show significant promise in enhancing remediation efficiency. For example, researchers at the Karlsruhe Institute of Technology in Germany have developed a method that incorporates enzymatic degradation and electrochemical filtration, achieving a remarkable 98% degradation of PET microplastics within 72 h, outperforming either method used independently (Ubani et al. 2022).

As these technologies advance, long-term monitoring will be essential to assess how microbial communities and ecosystems respond to bioremediation efforts and to ensure that no unintended ecological consequences arise. The impacts of microplastic bioremediation on higher trophic levels, such as fish and birds, remain largely uncharted territory and warrant investigation to evaluate efficiency and safety. Understanding these potential risks, including the release of greenhouse gases or the formation of toxic by-products, is crucial, as they may deter the continued use of these technologies (Petrić et al. 2011). Policy frameworks for the safe disposal of bioremediated waste are equally important for the sustainable implementation of bioremediation technologies. Collaboration among researchers, policymakers, and stakeholders will be vital in addressing the challenges posed by microplastic pollution and developing effective bioremediation strategies (Serralha and Coelho 2024). Transparent communication and community engagement are necessary for addressing public concerns and building trust in bioremediation practices.

Several decision-making frameworks have been proposed for various bioremediation techniques, including biodegradation, mycoremediation, rhizosphere remediation, and phytoremediation strategies like phytoextraction, floating wetlands, and soil microorganism-assisted remediation (Galitskaya et al. 2016). Each of these frameworks takes into consideration complex matrices involving human, environmental, legislative, geopolitical, and economic factors. There tends to be an inherent tradeoff between the effectiveness of a chosen method and its associated risks (Orellana et al. 2022). According to the established procedures, factors such as bioremediation efficiency, technological feasibility, risk, and costs associated with different technologies should be weighed in order to support the selection of the most suitable method for each specific hydraulic containment scenario, effectively allowing stakeholders to analyze and understand the tradeoffs between effectiveness and risks inherent in bioremediation technologies (Liang et al. 2011).