Persistent organic pollutants (POPs) pose a significant threat to global ecosystems and human health due to their resistance to degradation and their tendency to bioaccumulate. These toxic compounds, ranging from industrial chemicals like polychlorinated biphenyls (PCBs) to pesticides like DDT and unintentionally released substances such as dioxins, are a pressing environmental concern. Traditional remediation methods for POPs are often costly and can lead to secondary pollution, necessitating the development of more sustainable and economical solutions.

A comprehensive review by Sharma et al., published in Current Pollution Reports , sheds light on the pivotal role of organic and biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More amendments in enhancing the bioremediation of POP-contaminated soils. These amendments, which include materials like composted manure, biosolids, municipal solid waste, and biochar, are traditionally used to improve soil health and crop productivity. However, their ability to transform soil properties and influence POP dynamics makes them invaluable tools for environmental cleanup.

The review highlights that organic and biochar amendments work by changing soil pHpH is a measure of how acidic or alkaline a substance is. A pH of 7 is neutral, while lower pH values indicate acidity and higher values indicate alkalinity. Biochars are normally alkaline and can influence soil pH, often increasing it, which can be beneficial More, organic matter content, and soluble organic carbon levels. This can shift POPs from solid to aqueous phases, making them more accessible for microbial breakdown. Biochar, with its high surface area and excellent sorption properties, also functions as an electron donor, acceptor, or shuttle for microorganisms, facilitating various biological and chemical reactions that degrade POPs.

The application of these amendments can significantly accelerate the biodegradation of POPs through “biostimulation” and “bioaugmentation” of both native and introduced microorganisms. For instance, combining compost with arbuscular mycorrhizal fungiThese are friendly fungi that form a partnership with plant roots. They act like an extension of the root system, helping plants access water and nutrients more effectively. Biochar can create a cozy habitat for these helpful fungi, boosting their growth and improving plant health.   More (AMF) led to a 53.3% degradation rate of BDE-209 in rice rhizospheres within 120 days. Successful pilot-scale bioremediation efforts using composting have even achieved over 70% removal efficiencies for various POPs.

One notable finding from the review emphasizes biochar’s effectiveness as a microbial carrier. When wood biochar was used to carry PCB-degrading strains, the PCB removal rate significantly increased from 2.3–6.8% (with direct inoculation of free microbes) to 7.2–30.3%. Similarly, biochar inoculated with Pseudomonas plecoglossicida led to a 42.8% reduction in BDE-47 within 60 days, compared to a mere 11.8% with free bacteria. In a compelling example, green garden waste biochar, when combined with ryegrass for rhizoremediation of PCBs, achieved an outstanding 85% degradation rate in just five months.

Despite these promising results, the review also addresses limitations. The effectiveness of these amendments can depend on site-specific conditions, such as soil organic matter content. For instance, biochar enhanced PCB biodegradation only in soils with low organic matter content (3.5 g/kg). Moreover, some amendments might introduce new contaminants or lead to nutrient imbalances, and their long-term stability and regeneration potential require further study.

The integration of various remediation techniques, known as synergistic remediation, is gaining traction. Combining organic and biochar amendments with other methods like phytoremediationThis is a technique that uses plants to clean up contaminated soil or water. Biochar can enhance phytoremediation by improving soil conditions and promoting plant growth, allowing plants to absorb and break down pollutants more effectively.   More or chemical oxidation has shown enhanced bioremediation processes, often exceeding 60-70% efficiency. Advanced approaches, such as biomolecular engineering to enhance microbial biocatalytic ability, and the use of microbial fuel cells for POP treatment, also show considerable promise for the future.

In conclusion, organic and biochar amendments offer a sustainable and effective pathway for remediating POP-contaminated soils. By leveraging their ability to improve soil properties, enhance microbial activity, and act as effective carriers, these materials are crucial for mitigating POP pollution and restoring environmental health.

Source: Sharma, S., Bolan, S., Mukherjee, S., Petruzzelli, G., Pedron, F., Franchi, E., Fonseka, W., Wijesekara, H., Wang, L., Hou, D., Siddique, K. H. M., & Bolan, N. (2025). Role of Organic and Biochar Amendments on Enhanced Bioremediation of Soils Contaminated with Persistent Organic Pollutants (POPs). Current Pollution Reports, 11(3), 33.