Search Results (92)

Widespread antibiotic residues are accumulating in the environment, potentially causing adverse effects for humans, animals, and the ecosystem, including an increase in antibiotic-resistant bacteria, resulting in worldwide concern. There are various commonly used physical, chemical, and biological treatments for the degradation of antibiotics. However, the elimination of toxic end products generated by physicochemical methods and the need for industrial applications pose significant challenges. Hence, environmentally sustainable, green, and readily available approaches for the transformation and degradation of these antibiotic compounds are being sought. Herein, we review the impact of sustainable fungal laccase-based bioremediation strategies. Fungal laccase enzyme is considered one of the most active enzymes for biotransformation and biodegradation of antibiotic residue in vitro. For industrial applications, the low laccase yields in natural and genetically modified hosts may constitute a bottleneck. Methods to screen for high-laccase-producing sources, optimizing cultivation conditions, and identifying key genes and metabolites involved in extracellular laccase activity are reviewed. These include advanced transcriptomics, proteomics, and metagenomics technologies, as well as diverse laccase-immobilization technologies with different inert carrier/support materials improving enzyme performance whilst shifting from experimental assays to in situ monitoring of residual toxicity. Still, more basic and applied research on laccase-mediated bioremediation of pharmaceuticals, especially antibiotics that are recalcitrant and prevalent, is needed. Full article

Aerated accumulation bioreactors represent a promising alternative for the aerobic bioremediation of solid contaminated substrates. However, achieving homogeneous mixing and effective air distribution remains a key design challenge in solid-phase systems. This study presents the design and construction of a novel pilot-scale aerated bioreactor equipped with an angled-paddle agitation system, specifically developed to improve solid mixing and aeration. To evaluate the geometric configuration, a series of simulations were performed using the Discrete Element Method (DEM), with particle dynamics analyzed through the Lacey Mixing Index ($LMI$). Four paddle angles (0°, 15°, 45°, and 55°) were compared, with the 45° configuration achieving optimal performance, reaching $LMI$ values above 0.95 in less than 15 s and maintaining high homogeneity at a filling volume of 70%. These results confirm that the paddle angle significantly influences mixing efficiency in granular media. While this work focuses on engineering design and DEM-based validation, future studies will include experimental trials to evaluate biodegradation kinetics. The proposed design offers a scalable and adaptable solution for ex situ bioremediation applications. This work reinforces the value of integrating DEM simulations early in the bioreactor development process and opens pathways for further optimization and implementation in real-world environmental remediation scenarios. Full article

To promote environmentally sustainable remediation and resource recovery from ion-adsorption rare earth tailings (IRET), this study comprehensively investigated the previously isolated strain REO-01 by examining its sulfate-reducing performance, Cd(II) immobilization potential, and physiological and biochemical responses under varying environmental conditions. Strain REO-01 was identified as a Gram-negative facultative anaerobe with strong sulfate-reducing activity and effective Cd(II) immobilization capacity. During a 96 h incubation period, the strain entered the exponential growth phase within 36 h, after which the OD₆₀₀ values plateaued. Concurrently, the culture pH increased from 6.83 to 7.5, and the oxidation-reduction potential (ORP) declined to approximately −300 mV. Cd(II) concentrations decreased from 0.2 mM to 3.33 μM, corresponding to a removal efficiency exceeding 95%, while sulfate concentrations declined from 1500 mg/L to 640 mg/L, with a maximum reduction efficiency of 66.16%. The strain showed optimal growth at 25–40 °C and near-neutral pH (6–7), whereas elevated Cd(II) concentrations (≥0.2 mM) significantly inhibited cell growth. A sulfate concentration of 1500 mg/L was found to be optimal for cellular activity. Among the tested carbon sources, sodium lactate at 4.67 g/L yielded the most favorable results, reducing ORP to −325 mV, increasing pH to 7.6, and lowering Cd(II) and sulfate concentrations to 3.33 μM and 510 mg/L, respectively. These findings highlight the strong potential of strain REO-01 for simultaneous sulfate reduction and Cd(II) remediation, supporting its application in the in situ bioremediation and resource utilization of rare earth tailings. Full article

This study investigates the effect of nanoscale zero-valent iron (NZVI) and sediment microbial fuel cells (SMFCs) on the three typical heavy metals’ (Pb, Cr and As) removal and stabilization. Results showed that the combined use of NZVI and SMFCs obtained the highest removal efficiencies in the sediment (Pb 37.7 ± 2.2%, Cr 26.4 ± 1.5% and As 30.1 ± 2.0%) and overlying water (Pb 55.8 ± 2.3%, Cr 47.6 ± 1.9% and As 45.8 ± 2.1%). The use of an NZVI electrode can transform heavy metals with relatively weak binding into forms with stronger binding, thereby diminishing their bioavailability and toxicity. After 60 days of operation with the addition of NZVI in the SMFC system, over 50% of the Pb, Cr and As in the sediment was transformed into the residual fraction. An anodic microbial communities analysis indicated that operating a SMFC can mitigate the adverse effects of NZVI on the community diversity and increase the content of electrogenic bacteria in sediments. Consequently, our findings indicated that integrating SMFCs and NZVI represents a viable approach for remediating rivers contaminated with heavy-metal-polluted sediments. Full article

17β-estradiol (E2) contamination resulting from the widespread use of animal manure poses a new threat to the agricultural environment. Since anaerobic environments have been reported to significantly extend the persistence of E2, estrogen pollution of anaerobic farmland soils (e.g., paddy soils) is of particular concern, necessitating the development of in situ high-efficiency E2 bioremediation microorganisms. In this work, six E2-degrading strains were isolated from paddy soils, including strains from Elizabethkingia, Stenotrophomonas, Microbacterium, Ochrobactrum, Gordonia, and Acinetobacter. Among these strains, Ochrobactrum sp. AEPI-SP11 and Acinetobacter sp. AEPI-SP17 were able to degrade over 90% of 20 mg/L E2 within 5 days. Although both AEPI-SP11 and AEPI-SP17 exhibited strong tolerance to pH, temperature, and initial E2 concentrations (2, 5, 20, and 50 mg/L), only AEPI-SP17 was capable of biodegrading E2 under anaerobic conditions. Based on genomic analysis, we further obtained the whole genome sequences of AEPI-SP11 and AEPI-SP17 and identified and compared potential genes responsible for estrogen degradation in the two strains. Overall, this work significantly enhances our understanding of E2-degrading strains in paddy soils, offers valuable insights into the degradation mechanisms under varying conditions, and provides potential microbial resources for the effective control of E2 pollution in farmlands. Full article

The weathering of seafloor hydrothermal sulfides is facilitated by microbial activities, yet the specific mechanisms of different sulfide types are not well understood. Previous studies have primarily been carried out under laboratory conditions, making it difficult to accurately replicate the complex in situ conditions of deep-sea hydrothermal fields. Herein, we deployed two well-characterized pyrite (Py)-dominated and chalcopyrite (Ccp)-dominated sulfide slices, which were placed 300 m from an active venting site in the Wocan-1 hydrothermal field (Carlsberg Ridge, Northwest Indian Ocean) for an 18-month in situ incubation experiment. Microscopic observations and organic matter analyses were conducted on the recovered sulfide slices to investigate the microbial weathering features of different sulfide types. Our results demonstrated that the weathering of the Py-dominated sulfide sample was primarily mediated by extracellular polymeric substances (EPSs) through indirect interactions, whereas the Ccp-dominated sulfide sample exhibited both direct microbial dissolution, resulting in the formation of distinct dissolution pits, and indirect EPS-mediated interactions. Four distinct phases of microbe–sulfide interactions were identified: approach, adsorption, stable attachment, and extensive colonization. Furthermore, the weathering products and biomineralization structures differed significantly between the two sulfide types, reflecting their different microbial colonization processes. Our study confirms that microorganisms are crucial in seafloor sulfide weathering. These findings advance our understanding of microbial-driven processes in sulfide mineral transformations and their role in marine ecosystems. Our findings are also valuable for future research on biogeochemical cycles and for developing bioremediation strategies for deep-sea mining. Full article

Difenoconazole, a broad-spectrum systemic fungicide, can effectively prevent and control plant diseases such as rice blast, leaf spot, and black spot caused by Colletotrichum godetiae, Alternaria alternata, and Neopestalotiopsis rosae. However, its residual accumulation in the environment may pose potential toxicity risks to non-target organisms. In this study, a highly efficient DIF-degrading microbial consortium TA01 was enriched from long-term pesticide-contaminated soil by a laboratory-based adaptive evolution strategy. The microbial consortium TA01 was able to degrade 83.87% of 50 mg/L of DIF within 3 days. In addition, three intermediate metabolites were identified using HPLC–MS/MS, and the results indicated that the degradation of DIF by microbial consortium TA01 may involve catalytic reactions such as hydrolysis, dehalogenation, and hydroxylation. High-throughput sequencing results showed that Pantoea, Serratia, Ochrobactrum, and Bacillus were the dominant microbial members involved in the degradation process. Finally, bioremediation capacity experiments showed that inoculation with microbial consortium TA01 was able to accelerate the degradation of DIF in the water–sediment system. The findings of this study not only enrich the microbial resources available for DIF degradation but also offer new potential strategies for in situ remediation of DIF contamination. Full article

Crude oil and its derivates are among the most important environmental pollutants, where P. aeruginosa strains producing AlkB1 and AlkB2 alkane hydroxylases are often involved in their biodegradation. The aim of this study was to analyze antibiotic resistance and virulence determinants of a P. aeruginosa isolate cultured from a hydrocarbon-contaminated soil sample from Ogoniland, Nigeria, and to compare its characteristics with P. aeruginosa isolates cultured worldwide from hydrocarbon-contaminated environments or from clinical samples. Using the ResFinder reference database, a catB7 chloramphenicol acetyltransferase gene, an ampC-type PDC β-lactamase gene, and an OXA-50 type β-lactamase gene were identified in all P. aeruginosa strains analyzed in this study. In some of these P. aeruginosa strains, loss-of-function mutations were detected in the regulatory genes mexR, nalC, or nalD, predicting an efflux-mediated acquired antibiotic-resistance mechanism. Several P. aeruginosa sequence types that were associated with oil-contaminated environments have also been cultured from human clinical samples worldwide, including sequence types ST532, ST267, ST244, and ST1503. Our findings also indicate that environmental P. aeruginosa may serve as the source of human infections, warranting further studies from a One Health perspective about the application of P. aeruginosa for the in situ bioremediation of hydrocarbon-contaminated sites. Full article

Volatile and semi-volatile compounds, such as petroleum hydrocarbons and equipment lubricating oils, often contaminate soil due to accidents, posing significant ecological and health risks. Traditional soil remediation methods, such as thermal desorption and bioremediation, are time-consuming and resource-intensive, prompting researchers to explore more efficient alternatives. This study investigates the effectiveness of an in situ reactor for microwave-assisted soil remediation, specifically focusing on the impact of soil type and moisture content on pollutant removal efficiency. The reactor, designed to operate within a modified household microwave oven, provides direct microwave irradiation to the soil surface, enabling precise control of heating conditions. Experiments were conducted using soil samples of varying particle sizes and moisture levels under standardized conditions (1000 W microwave power, 2.45 GHz frequency). The results show that moisture content plays a critical role in pollutant removal efficiency, with an optimal moisture content of 10 wt % enhancing microwave absorption and energy transfer, thus improving pollutant recovery. In comparison with traditional resistive heating, microwave heating achieved a faster temperature rise and higher final temperatures, significantly improving pollutant removal efficiency in a shorter time frame. This study highlights the advantages of microwave heating, including its superior energy efficiency, faster pollutant volatilization, and the potential for optimized soil remediation in real-world applications. These findings provide valuable insights for the development of more sustainable and efficient soil remediation technologies. Full article

Polycyclic aromatic hydrocarbons (PAHs) are considered hazardous pollutants due to their negative impact on the environment and human health. PAHs can accumulate and be retained in the soil, so PAH pollution is a worldwide problem. This review paper highlights the sources of PAH soil pollution, factors affecting the bioavailability of PAHs in soil, and soil bioremediation methods, as well as the advantages and limitations of the application of these methods. Aspects regarding the impact of the application of surfactants are presented in order to obtain good bioavailability during PAH bioremediation. Bioremediation techniques of soil polluted by these hydrocarbons are addressed: phytoremediation, rhizoremediation, composting, vermiremediation, micoremediation, and electrokinetic bioremediation of PAH-polluted soils. A comprehensive overview of bioremediation technologies for PAH-polluted soils is needed so that the right soil remediation technology is chosen. It has been observed the bioremediation of contaminated soils through rhizoremediation proved to be an effective process, the future of organic pollutants in interaction with plants and microbes must be researched. Vermiremediation, electrokinetic bioremediation, and microcomposting are effective processes for treating soils in situ. Phytoremediation is a sustainable and ecological method of PAH depollution. It improves soil fertility by releasing different organic matter in the soil, and it can be applied on a large scale. Full article

Phosphorus (P) is a key component that limits plant growth. P is a limited resource; hence, effective P management is needed to increase plant P consumption from the soil and reduce P input levels through fertilization. In light of these difficulties, the goal of this review is to investigate the role of soil electrokinetics (SEKs)—a physicochemical approach—as the main approach in our in-depth analysis of publication history across six P-management research search engines to ensure sustainable management. This review covers the management of P using the SEKs from a number of perspectives, such as P injection in soil to improve bioremediation efficiency; P specific and synergistic separation from other related elements; increasing plant P availability and reusing it as fertilizer; and P removal from soil and sewage sludge. In terms of P adsorption, after seven days on kaolin, no organic P adsorption was observed, while inorganic P adsorbed to a maximum of 73% after six days. This implies that in low-permeability soils, the organic P source can be a practical source of P during in situ bioremediation. With the use of chemical additives, the specific and synergistic separation of P from/with other elements was made possible. When compared to the region near the cathode, P availability for the plant was higher in the vicinity of the anode electrode. P can be recycled and used as fertilizer. The iron electrodes result in a noticeably greater removal of phosphate than titanium electrodes. Further research is required to offer a technical solution for the proper handling of P, as there has been little research on P management from many perspectives. Full article

Contamination or pollution of our environment has become a real global concern, especially in parallel with the increasing evolution of urbanization and industrialization, which in turn have released a plethora of different pollutants that end up being deposited in soils. It is crucial to investigate solutions that can minimize the extent of damage, and that are cost-effective, feasible and environmentally friendly, to treat a wide variety of contaminants in soils, as well as to detoxify various compounds. Bioremediation is a safe technique that has demonstrated satisfactory results and is easy to apply and maintain. This technique explores the degradation pathways of various biological agents (microorganisms, plants, algae, etc.) to neutralize contaminants. It is based on biodegradation through a complete mineralization of organic pollutants into inorganic innocuous compounds, such as carbon dioxide and water. This review aims to determine the feasibility of bioremediation as a cleanup technology for soils contaminated with pesticides, agrochemicals, chlorinated compounds, heavy metals, organic halogens, greenhouse gases, petroleum hydrocarbons, and many others, either in situ or ex situ. Different bioremediation approaches are described and compared, showing their advantages and drawbacks from a critical point of view. Moreover, both the economic and technical barriers of bioremediation are addressed, along with the outlook for the role of microorganisms in the process, the aim to identify future directions, and the application feasibility of this process. Full article

The remediation of contaminated groundwater is a critical component of environmental management. In situ bioremediation (ISB) is a technique used to treat contaminated groundwater by promoting the activity of microorganisms, which transform harmful substances into less toxic or non-toxic forms. The present study investigates social issues regarding the sustainability approach applied to the remediation of contaminated sites by analyzing occupational health and safety (OH&S) impacts on workers involved in the remediation process. Occupational chemical risk is analyzed by comparing two techniques for the remediation of groundwater contaminated by chlorinated aliphatic hydrocarbons (CAHs): the pump-and-treat system and biological barriers. A contaminated Italian site, located near an industrial waste disposal site, was analyzed, applying a quantitative approach for chemical risk assessment. This approach is based on the use of a validated algorithm (SNPA software) and environmental measurement campaigns of chemical agents. This study (as far as the authors know) is the first research carried out in this field and shows that the adoption of bio-barriers for remediation is intrinsically safer in terms of OH&S impacts on workers. Full article

This paper presents the implementation of an innovative solution based on heterogeneous autonomous vehicles to tackle maritime pollution (in particular, oil spills). This solution is based on native microbial consortia with bioremediation capacity, and the adaptation of air and surface autonomous vehicles for in situ release of autochthonous microorganisms (bioaugmentation) and nutrients (biostimulation). By doing so, these systems can be applied as the first line of the response to pollution incidents from several origins that may occur inside ports, around industrial and extraction facilities, or in the open sea during transport activities in a fast, efficient, and low-cost way. The paper describes the work done in the development of a team of autonomous vehicles able to carry as payload, native organisms to naturally degrade oil spills (avoiding the introduction of additional chemical or biological additives), and the development of a multi-robot framework for efficient oil spill mitigation. Field tests have been performed in Portugal and Spain’s harbors, with a simulated oil spill, and the coordinate oil spill task between the autonomous surface vehicle (ASV) ROAZ and the unmanned aerial vehicle (UAV) STORK has been validated. Full article

The presence of high concentrations of geogenic arsenic (As) in groundwater poses a serious threat to the health of millions of individuals globally. This paper examines the research progress of groundwater with high concentrations of geogenic As through a comprehensive literature review and analysis, covering distribution, health risks, in situ remediation, regulatory technologies, and development trends, to establish a reference for future research. The global distribution of geogenic high-As groundwater is mainly in inland basins and river deltas of countries in South Asia, East Asia, and South America. High-As risk areas can be modeled using hydrogeologic data and field measurements. This modeling approach allows for assessing and measuring potential areas of high-As groundwater. In order to provide safe drinking water promptly and effectively to areas affected by high-As groundwater, in situ rapid detection and remediation techniques have been given significant attention. This paper introduces household- or community-scale As removal technologies, including flocculant–disinfectant, bucket treatment units, use of activated alumina, use of nano zero-valent iron, aquifer iron coating technology, and bioremediation, summarizing the basic mechanisms of arsenic removal for each technology. Guaranteeing the sustainability of site-scale remediation technologies, reasonable aquifer management, and exploring alternative water sources are crucial for combating high-As groundwater contamination. Future studies should aim to elucidate the mechanisms of As’s coexistence with other pollutants in groundwater, effectively treating As-containing wastes or sludge produced during the treatment process and exploring better treatment options. Full article