Table of Contents
Sustainable soil remediation represents a critical intersection of environmental science, public health, and ecological stewardship. As global soil degradation accelerates due to industrialization, intensive agriculture, and climate change, the need for effective, environmentally responsible remediation strategies has never been more urgent. The United Nations Food and Agriculture Organization (FAO) has projected that by 2050, nearly 90% of the world’s soil resources will be at risk due to factors such as erosion, overuse of agrochemicals, and industrial pollution. This comprehensive guide explores the principles, techniques, and implementation strategies that define sustainable soil remediation in the modern era.
Understanding Sustainable Soil Remediation
Sustainable soil remediation encompasses a holistic approach to restoring contaminated soil while minimizing environmental impact and maximizing long-term ecological benefits. Unlike traditional remediation methods that often prioritize speed and efficiency at the expense of environmental health, sustainable approaches integrate ecological, economic, and social considerations into every phase of the remediation process.
Biological remediation including bioremediation and phytoremediation employs microorganisms and/or plants to remove, degrade and/or immobilize contaminants in the environment. With its advantages being low-cost, simple operation, and eco-friendly, biological remediation has wide application in restoring contaminated sites. These methods represent a fundamental shift from conventional “pump and treat” and “dig and dump” techniques that have dominated the field for decades.
Chemical and physical methods such as precipitation, ion exchange, chemical leaching, oxidation-reduction, immobilization, electro-kinetics, and vitrification have been used for soil remediation, but they often generate toxic sludge, and disrupt soil quality. The limitations of these traditional approaches have driven researchers and practitioners toward more sustainable alternatives.
The Global Soil Contamination Crisis
The scale of soil contamination worldwide demands immediate and sustained attention. Over 10 million contaminated sites globally are estimated to contain hazardous levels of pollutants, including heavy metals (e.g., Pb, Cd, As), petroleum hydrocarbons, pesticides, polychlorinated biphenyls (PCBs), and emerging contaminants like microplastics and pharmaceuticals. This widespread contamination threatens food security, ecosystem stability, and human health across multiple continents.
As soil sustains over 95% of the global food supply, such degradation poses a critical threat to food security and ecosystem stability. Among the myriad environmental pollutants, heavy metals (HMs) like arsenic (As), lead (Pb), cadmium (Cd), and chromium (Cr) stand out as insidious threats to the environment. The bioaccumulation of these contaminants through food chains presents severe risks to human health and ecological balance.
Soil pollution, exacerbated by rapid urbanization, intensive agriculture, and climate change, introduces a complex mix of contaminants such as heavy metals, pesticides, per- and polyfluoroalkyl substances, and microplastics into the soil. These pollutants pose severe risks to environmental health and agricultural productivity by altering soil functionality and contaminant mobility.
Core Principles of Sustainable Soil Remediation
The foundation of sustainable soil remediation rests on several interconnected principles that guide decision-making and implementation strategies. These principles ensure that remediation efforts not only address immediate contamination concerns but also contribute to long-term environmental health and resilience.
Minimizing Environmental Footprint
Research has increasingly shifted towards microbial-based bioremediation approaches, which are recognized for their cost-effectiveness, environmental sustainability, and minimal ecological disruption. This principle emphasizes reducing energy consumption, limiting greenhouse gas emissions, and avoiding the generation of secondary pollutants during the remediation process.
Biochar contributes to climate change mitigation through long-term carbon storage and by reducing greenhouse gas emissions, such as N₂O and CH₄. By managing crop residues and preventing their burning, biochar not only improves soil quality but also enhances nutrient and water use efficiency, further promoting sustainability.
Leveraging Natural Processes
Sustainable remediation prioritizes techniques that work with natural biological and chemical processes rather than against them. Bioremediation broadly refers to any process wherein a biological system (typically bacteria, microalgae, fungi in mycoremediation, and plants in phytoremediation), living or dead, is employed for removing environmental pollutants from air, water, soil, fuel gasses, industrial effluents etc., in natural or artificial settings. The natural ability of organisms to adsorb, accumulate, and degrade common and emerging pollutants has attracted the use of biological resources in treatment of contaminated environment.
Preventing Secondary Pollution
A critical aspect of sustainable remediation involves ensuring that cleanup efforts do not create new environmental problems. The environmental implications of surfactant use emphasize the need for selecting biodegradable and environmentally friendly surfactants to minimize secondary pollution. This principle requires careful consideration of all inputs, byproducts, and potential unintended consequences of remediation activities.
Integrating Circular Economy Principles
The remediation treatment train approach encourages resource recovery, strengthens the circular economy, and employs a Life Cycle Assessment (LCA) framework to assess the environmental impacts of different remediation strategies. The study explores mechanisms to integrate sustainability principles into soil remediation practices. This approach transforms contaminated soil from a liability into a potential resource, aligning with broader sustainability goals.
This approach aligns with the principles of sustainable remediation practices, the emerging EU Soil Health law, and the United Nations Sustainable Development Goals (SDGs). Opportunities for resource recovery from contaminated soil can include i) extraction of valuable metals, ii) production of biofuels, iii) production of amendment, and iv) bioremediation.
Comprehensive Bioremediation Techniques
Bioremediation harnesses the metabolic capabilities of microorganisms to degrade, transform, or immobilize contaminants in soil. This biological approach offers numerous advantages over conventional physical and chemical methods, including lower costs, reduced environmental impact, and the potential for complete mineralization of organic pollutants.
Microbial Bioremediation Mechanisms
Bioremediation is the process/method which detoxify the heavy metals with the help of microorganism in environment. Microorganisms employ various mechanisms to remediate contaminated soil, including biodegradation, biotransformation, biosorption, and bioaccumulation. These processes can occur under aerobic or anaerobic conditions, depending on the contaminant type and environmental conditions.
Microbial-assisted bioremediation particularly involving plant growth-promoting rhizobacteria (PGPRs) has emerged as a promising approach to enhance HMs detoxification while supporting plant health and soil recovery. Recent research has demonstrated the remarkable potential of specific bacterial strains in heavy metal remediation.
These studies underscore the promising role of PGPRs in mitigating heavy metal toxicity, enhancing nutrient cycling, and restoring soil biological activity, thereby contributing to sustainable soil health management in contaminated agroecosystems.
In-Situ Bioremediation Approaches
These techniques involve treating polluted substances at the site of pollution. It does not require any excavation; therefore, it is accompanied by little or no disturbance to soil structure. In-situ methods offer significant advantages in terms of cost-effectiveness and minimal site disruption.
Bioventing: Bioventing is a process that increases the oxygen or air flow into the unsaturated zone of the soil, this in turn increases the rate of natural in situ degradation of the targeted hydrocarbon contaminant. This technique is particularly effective for petroleum hydrocarbon contamination in vadose zone soils.
Biosparging: Similar to bioventing but applied to saturated zones, biosparging introduces air or oxygen into groundwater to stimulate aerobic biodegradation of contaminants. The air injection pressure must be great enough to overcome the hydrostatic pressure of the water and resistance to air flow through the soil.
Natural Attenuation: Bioremediation can be carried out by bacteria that are naturally present. In biostimulation, the population of these helpful bacteria can be increased by adding nutrients. This passive approach relies on naturally occurring processes to reduce contaminant concentrations over time.
Ex-Situ Bioremediation Methods
Ex-situ techniques involve excavating contaminated soil and treating it in controlled environments. While generally more expensive than in-situ methods, they offer greater control over treatment conditions and can achieve faster remediation rates.
Biopiles: Bioremediation, particularly biopile technology, offers an environmentally friendly approach by leveraging microbial activity to degrade pollutants. The efficiency of biopiles depends on key factors such as moisture, temperature, nutrient availability, oxygen levels, and microbial diversity. Biopiles combine excavated soil with amendments and aeration systems to optimize microbial activity.
Landfarming: Landfarming, or land treatment, is a method commonly used for sludge spills. This method disperses contaminated soil and aerates the soil by cyclically rotating. This process is an above land application and contaminated soils are required to be shallow in order for microbial activity to be stimulated.
Composting: Windrow systems are similar to compost techniques where soil is periodically turned in order to enhance aeration. This periodic turning also allows contaminants present in the soil to be uniformly distributed which accelerates the process of bioremediation.
Advanced Biochar-Based Systems
The biochar-activated persulfate (PS)-based advanced oxidation process (AOP) has emerged as a promising strategy for the sustainable remediation of organic-contaminated soils. This innovative approach combines the adsorptive properties of biochar with chemical oxidation to achieve enhanced remediation efficiency.
The implementation of the Trichoderma reesei-laccase-biochar coupling system (TLBS) demonstrated remarkable efficiency in the bioremediation of heavy metals (Ni and Cd) and organic pollutants. The TLBS achieved a 93.63% reduction in Ni and 89.68% reduction in Cd bioavailability while simultaneously remediating a range of organic contaminants (71.41–96.79%), including antibiotics and pesticides.
Phytoremediation: Plant-Based Soil Restoration
Phytoremediation technologies use living plants to clean up soil, air and water contaminated with hazardous contaminants. This green technology leverages the natural capabilities of plants to extract, degrade, or stabilize pollutants, offering an aesthetically pleasing and cost-effective alternative to conventional remediation methods.
Phytoextraction
Phytoextraction involves using plants to absorb contaminants from soil and accumulate them in harvestable biomass. Phytoextraction could also be performed by non-hyperaccumulating plants (e.g. Populus and Salix). Although they take up only low levels of pollutants, owing to their high growth rate, such plants could in principle remove a considerable amount of contaminants from the soil.
Hyperaccumulating plants represent a specialized category with exceptional metal uptake capabilities. Hyperaccumulating plants are often metallophytes, i.e. they hyperaccumulate metals. Metallophytes are the basis of phytomining, a proposed technology for collecting valuable metals without excavating. This dual-purpose approach combines remediation with resource recovery.
One challenge to phytoremediation is that heavy metals are often insufficiently mobile to be taken up by the plants, hyperaccumulators or otherwise. This challenge prompted the invention of assisted phytoextraction, whereby a chelator is added to soil to increase metal solubility or mobilization so that the plants can absorb them more easily.
Phytostabilization
Phytostabilization lowers the mobility of substances in the soil, for example, by limiting the leaching of substances from the soil. This technique focuses on immobilizing contaminants rather than removing them, reducing their bioavailability and preventing their spread through the environment.
It focuses on the long term stabilization and containment of the pollutant. Unlike phytoextraction, phytostabilization focuses mainly on sequestering pollutants in soil near the roots but not in plant tissues. Pollutants become less bioavailable. Stabilization results in reduced erosion, runoff, leaching, in addition to reducing the bioavailability of the contaminant.
Phytodegradation
Phytodegradation (also called phytotransformation) is the use of plants to degrade organic pollutants. Plants accomplish this through enzymatic processes within their tissues or by releasing enzymes into the rhizosphere that break down contaminants into less harmful compounds.
The techniques used for phytoremediation are phytoextraction, phytofiltration, phytostabilization, phytovolatilization, and phytodegradation. Each technique addresses specific contamination scenarios and contaminant types.
Rhizofiltration and Hydraulic Containment
There are five basic types of phytoremediation techniques: 1) rhizofiltration, a water remediation technique involving the uptake of contaminants by plant roots; 2) phytoextraction, a soil technique involving uptake from soil, 3) phytotransformation, applicable to both soil and water, involving the degradation of contaminants through plant metabolism, 4) phyto-stimulation or plant-assisted bioremediation, also used for both soil and water, which involves the stimulation of microbial biodegradation through the activities of plants in the root zone, and 5) phytostabilization, using plants to reduce the mobility and migration potential of contaminants in soil.
Biological hydraulic containment occurs when some plants, like poplars, draw water upwards through the soil into the roots and out through the plant, which decreases the movement of soluble contaminants downwards, deeper into the site and into the groundwater.
Plant-Microbe Synergies
Microbial agents are effective in promoting plant growth and contaminant removal. With the inoculation of arbuscular mycorrhizal fungi, the biomass of Dandelion and Bermuda grass grown in a Cr-contaminated soil increased by 232 and 85%, respectively. As such, the inoculated microbes improve nutrient absorption, decrease the toxic effects of contaminants, and secrete plant hormones to promote plant growth, thereby enhancing phytoremediation.
Plant growth-promoting bacteria, or PGPB, are soil bacteria in the rhizosphere that enhance plant productivity by increasing nutrient bioavailability, secreting metabolites and hormones that stimulate increased plant growth, and secreting antibiotics that prevent pathogenic infection. PGPB have been shown to assist heavily with enhancing the transport of soil pollutants like heavy metals from the soil into the roots of hyperaccumulators via phytostimulation. PGPB increase transport speed by improving plant metabolic processes and biomass production, and by producing chelating or solubilizing agents that mobilize heavy metals, overall improving phytoremediation efficiency.
Physical and Chemical Remediation Methods
While biological methods form the cornerstone of sustainable remediation, certain physical and chemical techniques play important complementary roles, particularly when integrated into treatment trains or when dealing with specific contamination scenarios.
Soil Washing and Flushing
A recent study reported by Zhao et al, in 2024 provides a comprehensive review of surfactant-enhanced soil washing techniques for remediating oil-contaminated soils. The study examines various surfactants, including synthetic surface-active agents and biosurfactants, and their effectiveness in enhancing the solubilization, desorption, and separation of petroleum hydrocarbons from soil matrices. Key findings highlight that surfactant-enhanced soil washing can significantly improve the removal of hydrophobic organic contaminants, with efficiency influenced by factors such as surfactant type, concentration, soil properties, and contaminant characteristics.
Soil washing physically separates contaminants from soil particles using water or chemical solutions. This technique is most effective for sandy soils and can remove a wide range of contaminants, including heavy metals and organic compounds. The process typically involves size separation, gravity concentration, and flotation to isolate contaminated fractions.
In-Situ Stabilization and Immobilization
In-situ stabilization techniques immobilize pollutants within the soil matrix, preventing their migration and reducing their bioavailability. This approach is particularly useful when complete removal is impractical or when dealing with large volumes of moderately contaminated soil.
Chemical methods like gypsum reclamation, electrokinetic remediation, and advanced oxidation processes (AOPs) focus on the mobilization and breakdown of contaminants, achieving high removal efficiencies epitomized by heavy metals and organics. These techniques can be optimized to minimize environmental impact when carefully implemented.
Advanced Oxidation Processes
Fenton-based processes, ozonation, and sulfate radical-based oxidation. Innovations in catalytic materials and the integration of unconventional methods have significantly improved the efficiency of AOPs. Advanced oxidation processes generate highly reactive species that can degrade recalcitrant organic contaminants.
PMS exhibits a high reactivity and a rapid degradation rate, making it particularly suitable for emergency scenarios involving complex contamination and the efficient removal of persistent organic pollutants. However, its lower environmental stability leads to a short-lived radical generation period. Additionally, its higher cost constrains large-scale, long-term applications.
Thermal Desorption
Thermal desorption uses heat to volatilize contaminants from soil, which are then collected and treated. Some of the physical processes are soil flushing and thermal desorption which can efficiently remove pollutants, but energy costs are high. While effective, the high energy requirements of thermal methods limit their sustainability unless powered by renewable energy sources.
Integrated and Nano-Remediation Approaches
The complexity of modern soil contamination often requires integrated approaches that combine multiple remediation techniques to achieve optimal results while maintaining sustainability principles.
Treatment Train Strategies
The use of a treatment train can help address the complexity of soil contamination and the challenges associated with remediation, such as the presence of multiple contaminants and the need to meet sustainability requirements. Treatment trains sequence different remediation technologies to leverage the strengths of each approach while compensating for individual limitations.
The study integrated bioventing and SVE at a lab-scale and demonstrated efficiency in the removal of over 99.5% of potentially toxic elements (PTEs) after 96 hours of air injection at a constant flow rate of 250 mL/min. This indicates that physical and chemical remediation approaches could be integrated to achieve better efficiency and reduced net environmental impact.
Integrated remediation approaches, such as the combination of biochar with microbial or electrokinetic systems, provide enhanced and more sustainable outcomes than single-method applications.
Nanotechnology in Soil Remediation
Sustainable materials, including nanotechnology-based solutions like nanoparticles and biosurfactants, further enhance the bioremediation process, improving pollutant removal and promoting long-term soil health. Nanomaterials offer unique properties that can enhance remediation efficiency through increased surface area and reactivity.
Nanotechnology supports microbial bioremediation by supplying essential nutrients or serving as catalysts to accelerate pollutant degradation. For instance, silver nanoparticles inhibit harmful microbial growth while encouraging beneficial microbial activity in the soil.
GO provide active sites for adsorbing contaminants. Heavy metals are removed through chemical bonding or ion exchange, while organic pollutants are adsorbed via π-π interactions, hydrophobic effects, or van der Waals forces.
Nano-remediation methods offer high contaminant removal efficiency but raise environmental and regulatory concerns that need careful evaluation. The potential for nanoparticle mobility and ecotoxicity requires careful assessment before widespread application.
Bioaugmentation and Biostimulation
Methods such as phytoremediation, bioaugmentation, and mycoremediation, enhance soil fertility and employ restorational biology while inventive methods like Microbially-Induced Calcite Precipitation (MICP) bolster soil strength. These biological enhancement strategies optimize natural remediation processes.
Bioaugmentation involves introducing specific microorganisms with enhanced degradation capabilities to contaminated sites. Biostimulation focuses on optimizing environmental conditions to promote the activity of indigenous microbial populations. The success of any phytoremediation approach primarily depends on optimizing the remediation potentials of native plants growing in polluted sites either by bioaugmentation with endogenous or exogenous plant rhizobacteria, or by biostimulation.
Site Assessment and Characterization
Effective sustainable remediation begins with comprehensive site assessment and characterization. Understanding the nature, extent, and behavior of contamination is essential for selecting appropriate remediation strategies and ensuring their success.
Contaminant Characterization
Thorough characterization involves identifying all contaminants present, their concentrations, distribution patterns, and chemical forms. Different contaminants require different remediation approaches, and co-contamination scenarios add complexity to remediation planning.
The pollutant ultimately determines which bioremediation method to use. The depth and spread of the pollutant are other important factors. Understanding contaminant mobility, bioavailability, and potential transformation pathways informs strategy selection.
Soil Properties and Conditions
Soil characteristics significantly influence remediation effectiveness. Key parameters include soil texture, pH, organic matter content, moisture levels, temperature, and microbial community composition. These factors affect contaminant behavior and the performance of biological remediation approaches.
Phytoremediation and plant-assisted bioremediation are most effective if soil contamination is limited to within 3 feet of the surface, and if groundwater is within 10 feet of the surface. Physical constraints must be considered when selecting remediation techniques.
Ecological Sensitivity Assessment
Evaluating the ecological context of contaminated sites ensures that remediation activities protect sensitive habitats, endangered species, and ecosystem services. This assessment should consider both current ecological conditions and restoration potential.
The perspective discusses the challenges and future directions in soil pollution research, particularly the need for robust policy frameworks and international cooperation to effectively manage and mitigate soil contamination. Emphasizing a multidisciplinary approach, this study calls for enhanced global standards, public engagement, and continued scientific research to develop sustainable solutions for soil remediation and to ensure the protection of vital soil resources for future generations.
Implementation Strategies and Best Practices
Successful implementation of sustainable soil remediation requires careful planning, stakeholder engagement, and adaptive management throughout the remediation lifecycle.
Remediation Design and Planning
It underscores the necessity for a comprehensive and systematic approach that takes into account the economic, social, and environmental consequences of remediation methodologies in the development of sustainable solutions. Design considerations should balance technical effectiveness with sustainability objectives.
The methodology adopted for this review involved a comprehensive examination of existing literature on advancements in soil remediation techniques. Emphasis was placed on evaluating advanced remediation strategies for their effectiveness in restoring degraded soils. Each method was critically analyzed based on environmental impact, practical applicability, and alignment with sustainability goals.
Monitoring and Performance Assessment
Continuous monitoring ensures that remediation proceeds as planned and allows for timely adjustments when needed. Monitoring programs should track contaminant concentrations, soil health indicators, and ecological recovery metrics.
Deep-learning algorithms, such as convolutional neural networks, analyze high-dimensional sensor data and hyperspectral images for soil pollution identification and spatial mapping. Machine learning approaches, such as random forests, support vector machines, and gradient-boosting models, have been applied in modeling source attribution or soil contaminant distribution. Additionally, advanced geostatistical techniques, such as Bayesian hierarchical modeling and kriging interpolation, provide frameworks to quantify uncertainties and predict contaminant transport at large scales.
Adaptive Management
Adaptive management recognizes that remediation is an iterative process requiring flexibility and responsiveness to new information. This approach involves regular evaluation of remediation progress, identification of challenges, and modification of strategies as needed to achieve remediation goals.
In the case of bioremediation, which involves the use of microorganisms, it can be implemented either in situ or ex situ, depending on factors like cost, site characteristics, and the type and concentration of pollutants. Phytoremediation, another biological treatment method, utilizes plants to extract, immobilize, or degrade pollutants, contributing to the overall remediation effort.
Stakeholder Engagement and Community Involvement
Recent community science projects, such as citizen-led microplastic monitoring campaigns, have demonstrated that informed community participation can enhance data collection capabilities and increase public awareness. By combining science with community outreach, “SoilSHOP” initiative led by the U.S. Agency for Toxic Substances and Disease Registry empowers individuals to take action and reduce exposure risks in their own environments.
Engaging local communities, landowners, and other stakeholders throughout the remediation process builds support, incorporates local knowledge, and ensures that remediation outcomes align with community needs and values.
Economic Considerations and Cost-Effectiveness
While sustainability encompasses environmental and social dimensions, economic viability remains a critical factor in remediation decision-making. Sustainable approaches often offer long-term cost advantages despite potentially higher initial investments.
Comparative Cost Analysis
The conventional methods of removing pollutants from the environment are associated with numerous issues, such as partial removal, needing high energy, producing a significant amount of toxic sludge, being limited to a small area, and being costly. The economic burden of soil remediation by physical methods can be understood by the report of Salt et al.
In comparison to conventional physicochemical treatment methods bioremediation may offer advantages as it aims to be sustainable, eco-friendly, cheap, and scalable. Biological methods typically require lower capital investment and operating costs compared to physical and chemical alternatives.
Ideally, these techniques ought to be less expensive compared to ex situ bioremediation techniques, due to no extra cost required for excavation processes; nonetheless, cost of design and on-site installation of some sophisticated equipment to improve microbial activities during bioremediation is of major concern.
Life Cycle Cost Assessment
In summary, the use of LCA to evaluate sustainable soil remediation technologies has several advantages. Life cycle assessment provides a comprehensive framework for evaluating the total environmental and economic costs of remediation strategies from inception through completion and long-term monitoring.
This holistic approach accounts for direct costs, indirect costs, long-term maintenance requirements, and potential benefits such as land value restoration and ecosystem service enhancement.
Resource Recovery and Value Creation
Resource recovery from contaminated soil is an emerging area of research that seeks to maximize the use of resources contained in contaminated soil while offering sustainable solutions to mitigate environmental pollution. This approach aligns with the principles of sustainable remediation practices, the emerging EU Soil Health law, and the United Nations Sustainable Development Goals (SDGs).
Innovative approaches that extract value from remediation processes—such as metal recovery from hyperaccumulator biomass or biogas production from bioremediation—can offset remediation costs and create economic incentives for sustainable practices.
Challenges and Limitations
Despite significant advances in sustainable soil remediation, several challenges and limitations must be acknowledged and addressed to improve remediation outcomes.
Time Requirements
However, biological remediation takes time due to issues with its environmental adaptability, nutrient limitation, toxicity resistance and limited contaminant bioavailability. Biological methods typically require longer timeframes than physical or chemical approaches, which may not be acceptable in all situations.
Phytoremediation is not the answer to all contamination problems. Plants can generally only remediate soil or sediment in the top three feet of the soil because of their root lengths. Phytoremediation is generally limited to a depth of ten feet for groundwater remediation. As with bioremediation, phytoremediation is a research-intensive technology, and it can require long periods of time to effectively remediate a site.
Contaminant-Specific Limitations
Heavy metals are introduced into the environment by both anthropogenic activities and natural factors. Unlike organic pollutants, metals (or more properly, metal ions and metal compounds) cannot be degraded. This fundamental difference requires different remediation strategies for inorganic versus organic contaminants.
Phytoextraction and phytostabilization do not actually result in the destruction of the contaminant. Instead they accumulate or immobilize the contaminant. Although these are beneficial outcomes, destruction of the contaminant is generally preferred.
Site-Specific Constraints
Environmental conditions, site accessibility, regulatory requirements, and stakeholder concerns can all constrain remediation options. Taking all factors into consideration, bioremediation or phytoremediation may not be the best choice for all sites. A presentation at the 1996 Air and Waste Management Association Annual Meeting discussed the results of a treatability study for pesticide-contaminated soil, which addressed six technologies including two bioremediation approaches.
Knowledge Gaps and Research Needs
As a result, selecting appropriate plant species and microorganisms can have a considerable impact on the outcome of phytoremediation. A comprehensive study of the root chemistry of metal-tolerant plants and microorganisms under stress conditions is much needed. How microorganisms and plants work together for the wellness of the metaorganism (resulting from the plant–microbe association) under particular stress conditions is required for further study for effective remediation of contaminated soil.
Emerging Technologies and Future Directions
The field of sustainable soil remediation continues to evolve rapidly, with emerging technologies and approaches offering new possibilities for more effective and environmentally responsible contamination management.
Genetic Engineering and Biotechnology
An emerging field of study and one with significant potential for commercial use is the creation of transgenic plants with an outstanding capacity to chelate certain metals and prevent the deleterious effects of these metals. In the future, the bioremediation of polluted places may benefit from the coordinated use of traditional breeding techniques in combination with molecular biology.
Breeding programs and genetic engineering are powerful methods for enhancing natural phytoremediation capabilities, or for introducing new capabilities into plants. Genes for phytoremediation may originate from a micro-organism or may be transferred from one plant to another variety better adapted to the environmental conditions at the cleanup site. For example, genes encoding a nitroreductase from a bacterium were inserted into tobacco and showed faster removal of TNT and enhanced resistance to the toxic effects of TNT.
Artificial Intelligence and Machine Learning
Future research should integrate AI-driven analytical workflows for proactive pollution management. Advanced computational tools can optimize remediation design, predict treatment outcomes, and identify optimal combinations of remediation techniques for specific contamination scenarios.
This review paper provides a comprehensive overview of the last decade of biological remediation methods, with a focus on biopiles and their integration with other techniques. Integration of multiple data streams and modeling approaches will enhance decision-making and remediation effectiveness.
Advanced Materials and Catalysts
This review further summarizes advancements in the design of modified biochars, including metal (Fe, Cu, Co, Mn, Zn, and La), non-metal (N, S, B, P), and functional group modifications, aimed at enhancing the PS activation efficiency while minimizing secondary environmental risks.
This review emphasizes the sustainability-oriented evolution of PS/biochar technology, highlighting the importance of a cost-efficient implementation, ecological compatibility, and the rational engineering of smart, regenerable catalysts. These insights support the advancement of PS/biochar-based AOPs toward scalable, intelligent, and environmentally sustainable soil remediation.
Ecosystem-Based Management
Remediation practices based on circular economy principles and ecosystem-based management are more likely to ensure long-term soil health. Future approaches will increasingly integrate remediation with broader landscape restoration and ecosystem management objectives.
This concept of “brownfield-to-greenfield” conversion supports the growing trend of urban agriculture and land circularity, aligning well with the United Nations Sustainable Development Goals (SDGs). In this context, the objective of this review is to provide a holistic, comparative assessment of advanced soil remediation strategies by examining their mechanisms, effectiveness, sustainability, and alignment with global climate-resilient agriculture and SDGs.
Regulatory Framework and Policy Considerations
Effective sustainable soil remediation requires supportive regulatory frameworks that encourage innovation while protecting human health and the environment. Policy development must balance risk management with practical implementation considerations.
Remediation Standards and Goals
Establishing appropriate cleanup standards involves balancing risk reduction with technical and economic feasibility. Risk-based approaches that consider site-specific conditions and intended land use can promote more flexible and sustainable remediation strategies.
The study advocates for an integrative approach to soil remediation, one that harmoniously balances environmental sustainability, cost-effectiveness, and the specific requirements of contaminated sites. It underscores the necessity of a holistic strategy that combines various remediation methods, tailored to meet both regulatory compliance and the long-term sustainability of decontamination efforts.
International Cooperation and Standards
Soil contamination transcends national boundaries, requiring international cooperation to develop consistent standards, share best practices, and address transboundary pollution issues. Global initiatives and knowledge-sharing platforms facilitate the dissemination of sustainable remediation technologies and approaches.
Incentive Structures
Farmers and other societal stakeholders through incentives and legislative frameworks need to adopt to better land management, restoration and mitigation strategies with the help of modern and better knowledge technologies i.e. cost effective agricultural practices more friendly with natural and environmental ecosystems; such practices are essential to delivering sustainable communities.
Case Studies and Practical Applications
Real-world applications of sustainable soil remediation demonstrate the practical viability and effectiveness of these approaches across diverse contamination scenarios and geographic contexts.
Heavy Metal Remediation Success Stories
Recent study by Nie et al. (2025) showed that Pb resistant Pseudomonas sp. and Bacillus sp. treatment significantly decreased the Pb content, improved the available P, and K in the Pb contaminated rhizosphere soil. This demonstrates the dual benefits of bioremediation in both contaminant reduction and soil quality improvement.
The total phenol degradation is >90% in less than 4 days after a co-application of bacteria Burkholderia sp. to plants (Brassica chinensis and Ipomoea aquatica), compared to 38–50% without microbial amendment. These results highlight the enhanced effectiveness of integrated plant-microbe approaches.
Petroleum Hydrocarbon Remediation
Addition of organic waste (brewery spent grains) to waste lubricating oil contaminated soil enhanced the growth of Jatropha curcas and microbial proliferation at the rhizosphere, resulting in additional 33 % contaminant removal from 2.5 % used lubricating oil contaminated soil compared to treatment with J. curcas alone. This case demonstrates how waste materials can enhance phytoremediation effectiveness.
Multi-Contaminant Sites
Complex contamination scenarios involving multiple pollutant types require integrated remediation strategies. Treatment trains that sequence different technologies based on contaminant characteristics and site conditions have shown particular promise in addressing these challenging situations.
Soil Health Restoration Beyond Contaminant Removal
Sustainable remediation extends beyond simply removing contaminants to encompass comprehensive soil health restoration that supports long-term ecosystem function and productivity.
Microbial Community Restoration
The overlooked contributions of soil microorganisms in PS/biochar systems are discussed, highlighting their potential to complement chemical oxidation and contribute to eco-compatible remediation pathways. Restoring diverse and functional microbial communities is essential for sustainable soil health.
The biofertilizer significantly improved key soil physicochemical properties, including available N, P, K, and organic matter content. Enzymatic activities of dehydrogenase, alkaline phosphatase, and β-D-glucosidase were also substantially enhanced in biofertilizer-treated soils compared to control plots.
Nutrient Cycling and Fertility
Remediation strategies should support the restoration of nutrient cycling processes and soil fertility. This includes rebuilding organic matter content, enhancing cation exchange capacity, and promoting beneficial soil organisms that facilitate nutrient availability to plants.
Soil Structure and Physical Properties
Physical soil properties including aggregate stability, porosity, water-holding capacity, and infiltration rates must be considered in remediation planning. Techniques that preserve or enhance soil structure contribute to long-term sustainability and ecosystem function.
Conclusion and Path Forward
Sustainable soil remediation represents a paradigm shift from conventional cleanup approaches toward holistic strategies that integrate environmental protection, economic viability, and social responsibility. As global soil contamination continues to threaten food security, ecosystem health, and human well-being, the adoption of sustainable remediation principles becomes increasingly critical.
The field has made remarkable progress in developing and refining biological, physical, and integrated remediation technologies. Advances in bioremediation are revolutionizing soil remediation efforts using biological agents to degrade persistent contaminants such as PFAS. These innovations, combined with emerging technologies in genetic engineering, nanotechnology, and artificial intelligence, offer unprecedented opportunities for effective and sustainable contamination management.
Success in sustainable soil remediation requires multidisciplinary collaboration, stakeholder engagement, adaptive management, and continued research and innovation. We conclude by providing insights into the underlying remediation strategies’ mechanisms, key challenges, and future directions for the remediation of metal(loid)s-polluted agricultural soils with environmentally friendly techniques.
The path forward involves scaling up proven sustainable remediation technologies, developing supportive policy frameworks, building capacity among practitioners and stakeholders, and fostering international cooperation to address this global challenge. By embracing the principles of sustainable soil remediation and continuing to advance the science and practice of this critical field, we can protect and restore one of our most vital natural resources for current and future generations.
For additional resources on environmental remediation and soil health, visit the U.S. Environmental Protection Agency’s remediation portal, explore FAO’s Global Soil Partnership, or consult the Interstate Technology & Regulatory Council for technical guidance on sustainable remediation practices.