Some studies show how exposure to fields can enhance or reduce cell activity, with possible applicative consequences in the field of biotechnology, including biological techniques for depollution. In order to identify full-scale conditions that are suitable and potentially applicable for use in electromagnetic fields to stimulate and accelerate bioremediation processes, this paper offers an examination of the scientific literature that is available on the effects of fields on microorganisms, and a critical analysis of it. The biological effects at times contrast with each other.

Groundwater is the environmental matrix that is most frequently affected by anthropogenic hexavalent chromium contamination. Due to its carcinogenicity, Cr(VI) has to be removed, using environmental-friendly and economically sustainable remediation technologies. BioElectrochemical Systems (BESs), applied to bioremediation, thereby offering a promising alternative to traditional bioremediation techniques, without affecting the natural groundwater conditions. Some bacterial families are capable of oxidizing and/or reducing a solid electrode obtaining an energetic advantage for their own growth. In the present study, we assessed the possibility of stimulating bioelectrochemical reduction of Cr(VI) in a dual-chamber polarized system using an electrode as the sole energy source. To develop an electroactive microbial community three electrodes were, at first, inserted into the anodic compartment of a dual-chamber microbial fuel cell, and inoculated with sludge from an anaerobic digester. After a period of acclimation, one electrode was transferred into a polarized system and it was fixed at −0.3 V (versus standard hydrogen electrode, SHE), to promote the reduction of 1000 µg Cr(VI) L⁻¹. A second electrode, served for the set-up of an open circuit control, operated in parallel. Cr(VI) dissolved concentration was analysed at the initial, during the experiment and final time by spectrophotometric method. Initial and final microbial characterization of the communities enriched in polarized system and open circuit control was performed by 16S rRNA gene sequencing. The bioelectrode set at −0.3 V showed high Cr(VI) removal efficiency (up to 93%) and about 150 µg L⁻¹ day⁻¹ removal rate. Similar efficiency was observed in the open circuit (OC) even at about half rate. Whereas, purely electrochemical reduction, limited to 35%, due to neutral operating conditions. These results suggest that bioelectrochemical Cr(VI) removal by polarized electrode offers a promising new and sustainable approach to the treatment of groundwater Cr(VI) plumes, deserving further research.

Chromium is one of the most frequently used metal contaminants. Its hexavalent form Cr(VI), which is exploited in many industrial activities, is highly toxic, is water-soluble in the full pH range, and is a major threat to groundwater resources. Alongside traditional approaches to Cr(VI) treatment based on physical-chemical methods, technologies exploiting the ability of several microorganisms to reduce toxic and mobile Cr(VI) to the less toxic and stable Cr(III) form have been developed to improve the cost-effectiveness and sustainability of remediating hexavalent chromium-contaminated groundwater. Bioelectrochemical systems (BESs), principally investigated for wastewater treatment, may represent an innovative option for groundwater remediation. By using electrodes as virtually inexhaustible electron donors and acceptors to promote microbial oxidation-reduction reactions, in in situ remediation, BESs may offer the advantage of limited energy and chemicals requirements in comparison to other bioremediation technologies, which rely on external supplies of limiting inorganic nutrients and electron acceptors or donors to ensure proper conditions for microbial activity. Electron transfer is continuously promoted/controlled in terms of current or voltage application between the electrodes, close to which electrochemically active microorganisms are located. Therefore, this enhances the options of process real-time monitoring and control, which are often limited in in situ treatment schemes. This paper reviews research with BESs for treating chromium-contaminated wastewater, by focusing on the perspectives for Cr(VI) bioelectrochemical remediation and open research issues.

Sites contaminated by hexavalent chromium raise concerns relating to the toxicity of the pollutant, as well as for the increased solubility of its compounds, which helps it to seep into aquifers. Chemical and biological in situ treatment technologies, with good potential in terms of environmental sustainability, have recently been designed and implemented on a wide scale. A useful support tool is shown in the manuscript in the preliminary phase of assessing possible technologies applicable according to the site-specific characteristics of sites. The actual efficacy of the technologies identified should nevertheless be verified in laboratory trials and pilot tests.

Microbial electrochemical technologies represent innovative approaches to contaminated soil and groundwater remediation and provide a flexible framework for removing organic and inorganic contaminants by integrating electrochemical and biological techniques. To simulate in situ microbial electrochemical treatment of groundwater plumes, this study investigates Cr(VI) reduction within a bioelectrochemical continuous flow (BECF) system equipped with soil-buried electrodes, comparing it to abiotic and open-circuit controls. Continuous-flow systems were tested with two chromium-contaminated solutions (20–50 mg Cr(VI)/L). Additional nutrients, buffers, or organic substrates were introduced during the tests in the systems. With an initial Cr(VI) concentration of 20 mg/L, 1.00 mg Cr(VI)/(L day) bioelectrochemical removal rate in the BECF system was observed, corresponding to 99.5% removal within nine days. At the end of the test with 50 mg Cr(VI)/L (156 days), the residual Cr(VI) dissolved concentration was two orders of magnitude lower than that in the open circuit control, achieving 99.9% bioelectrochemical removal in the BECF. Bacteria belonging to the orders Solirubrobacteriales, Gaiellales, Bacillales, Gemmatimonadales, and Propionibacteriales characterized the bacterial communities identified in soil samples; differently, Burkholderiales, Mycobacteriales, Cytophagales, Rhizobiales, and Caulobacterales characterized the planktonic bacterial communities. The complexity of the microbial community structure suggests the involvement of different microorganisms and strategies in the bioelectrochemical removal of chromium. In the absence of organic carbon, microbial electrochemical removal of hexavalent chromium was found to be the most efficient way to remove Cr(VI), and it may represent an innovative and sustainable approach for soil and groundwater remediation. Integr Environ Assess Manag 2024;20:2033–2049. © 2024 The Author(s). Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC). Key Points The research offers valuable insights that can contribute to advancing microbial electrochemical remediation systems designed to reduce Cr(VI) in water-saturated soils. There were substantial differences from previously reported studies: acclimatization and/or adaptation and transfer of the electroactive bacterial community to Cr(VI) to a bioelectrochemical continuous flow system, no ion exchange membranes, and no nutrients and/or organic carbon added. The research was conducted to simulate most realistically the real conditions of Cr(VI)-contaminated aquifers, in terms of solid-to-liquid ratio, interactions among soil phases, and physicochemical parameters (pH and electrical conductivity). The outcomes achieved in the system for Cr(VI) reduction in water-saturated soil can demonstrate the feasibility of employing microbial electrochemical technology for the in situ treatment of contaminated aquifers, with interesting implications for economic and environmental sustainability.

Surfactants are widely used in domestic, industrial, and medical sectors, with a growing global market. However, synthetic surfactants pose environmental concerns, as they often enter ecosystems as recalcitrant organic pollutants due to their molecular properties. Residual surfactants persist in the environment, contributing to pollution. These issues highlight the need for safer, sustainable alternatives. Biosurfactants and bioemulsifiers are surface-active agents that reduce surface and interfacial tensions, derived from biological systems or microorganisms and alternative to synthetic surfactants. They can also facilitate environmental remediation, regenerative agriculture, and industrial applications. Key advantages include low toxicity, high biodegradability, potential derivation from renewable resources and domestic, urban and agricultural waste streams, increasing compatibility with circular economy principles. Therefore, they are fundamental to advancing environmental sustainability and allowing industries to transition towards greener solutions, aligning with global goals for zero-pollution objectives. This review highlights the application of these products in the bioremediation of contaminated soils and in enhanced oil recovery. It also addresses production challenges, particularly those related to cost and scalability, emphasizing the use of waste feedstock from strategic industries as a key factor in sustainability. Furthermore, recent advances and new strategies in metabolic, genetic, enzymatic and process engineering are discussed, which aims to optimize production yields and pave the way for broader commercialization. Available studies on biodegradability and toxicological profiles are reviewed to provide context for real-world applications. To support decision-making by managers and policymakers, real case studies are examined, along with a comparative analysis of the performance of biogenic versus synthetic surfactants in soil remediation. Finally, the review outlines current limitations and priority challenges in remediation practices that must be addressed. In conclusion, the successful commercialization and application of biosurfactants and bioemulsifiers will require a dual focus: advancing technological innovation to reduce production costs and aligning with operational demands, while also strengthening safety assessments to deepen understanding of their environmental and health impacts—ensuring their role as scientifically robust and socially responsible solutions. Graphical abstract