E. O. Dada, K. Njoku, A. Osuntoki et al.

Ethiopian Journal of Environmental Studies and Management • 2015

Soil plays crucial and strategic life-supporting roles as man and many other living organisms depend directly or indirectly on if for food and shelter. In spite of this fact, the soil is constantly subjected to various forms of abuse, including heavy metals pollution. The ecological destructive effect, high cost, and intensive labour requirement associated with ex situ physico-chemical remediation methods make the search for in situ remediation techniques inevitable. This paper gives an update on the remediation techniques that can be carried out in situ. Included in the review are more recent biological remediation methods, like vermiremediation, which are especially eco-friendly, cost effective, and sustainable. Key Words: Bioremediation, bioaccumulation, heavy metals, soil

R. Wu, Fangting Yao, Xiaoya Li et al.

Microorganisms • 2022

Manganese (Mn), as a cofactor of multiple enzymes, exhibits great significance to the human body, plants and animals. It is also a critical raw material and alloying element. However, extensive employment for industrial purposes leads to its excessive emission into the environment and turns into a significant threat to the ecosystem and public health. This review firstly introduces the essentiality, toxicity and regulation of Mn. Several traditional physicochemical methods and their problems are briefly discussed as well. Biological remediation, especially microorganism-mediated strategies, is a potential alternative for remediating Mn-polluted environments in a cost-efficient and eco-friendly manner. Among them, microbially induced carbonate precipitation (MICP), biosorption, bioaccumulation, bio-oxidation are discussed in detail, including their mechanisms, pivotal influencing factors along with strengths and limitations. In order to promote bioremediation efficiency, the combination of different techniques is preferable, and their research progress is also summarized. Finally, we propose the future directions of Mn bioremediation by microbes. Conclusively, this review provides a scientific basis for the microbial remediation performance for Mn pollution and guides the development of a comprehensive competent strategy towards practical Mn remediation.

Martin J. Hamper

Remediation Journal • 2020

<jats:title>Abstract</jats:title><jats:p>Polychlorinated biphenyls (PCBs) came onto the scene as an environmental threat quickly after they were discovered in humans and wildlife by Jensen in 1966. By October 1970, it was reported that PCBs were “truly ubiquitous pollutants” as PCBs were found at detectable concentrations in environmental samples throughout the world. Before 1971, the U.S. Environmental Protection Agency (EPA) reported that 26% of PCBs sold were used in open‐end use applications, such as caulks, sealants, plasticizers, surface coatings, ink, adhesive, and carbonless paper. Processing and distribution of PCBs in commerce were largely banned in the U.S. after July 1979 with certain continued uses authorized by the EPA. While PCBs were banned a long time ago, the ban had no immediate tangible effect on the continued use of regulated levels of PCBs in buildings constructed before the bans were implemented. Legacy buildings with PCB‐containing building materials continue to represent potential sources of indoor air, dust, outdoor air, and soil contamination. Where PCBs are present in building materials, they have the potential to pose a risk to building occupants. Proper removal of PCB‐containing materials is a highly effective approach to abating the risk. The removal can range from targeting specific building PCB‐containing materials through demolition of the building. Engineering and administrative controls can also be useful tools when addressing the risks posed by PCB‐containing materials.</jats:p>

O. González, M. Esplugas, C. Sans et al.

Water Science and Technology • 2008

<jats:p>A combined strategy of a photo-Fenton pretreatment followed by a Sequencing Batch Biofilm Reactor (SBBR) was evaluated for total C and N removal from a synthetic wastewater containing 200 mg L−1 of the antibiotic Sulfamethoxazole (SMX). Photo-Fenton reaction was performed with two different H2O2 concentrations (300 and 400 mg L−1) and 10 mg L−1 of Fe2 + . The pre-treated effluents with the antibiotic intermediates as sole carbon source, together with a nutrients solution, were used as feed for the biological reactor. The SBBR was operated under aerobic conditions to mineralize the organic carbon and the hydraulic retention time (HRT) was optimized down to 8 hours. Then, an anoxic denitrification stage of 24 hours of HRT was added right after the aerobic stage of the same duration in order to remove the NO3− generated along the chemical–biological treatment. TOC, COD and SMX concentrations together with O2 uptake rate (OUR) profiles were monitored in purpose of assessing the performance of the system. NO3−, NH4+ and total N concentrations were analyzed to find out the fate of N contained in the initial SMX molecule. A start up strategy resulted in the correct formation of a biofilm over the volcanic support. The total TOC removals achieved with the combination of the chemical and the biological processes were 75.7 and 87.7% for the low and the high H2O2 concentration pretreatments respectively. Practically all N present in the SMX solution was eliminated in the SBBR when the aerobic–anoxic strategy was used.</jats:p>

Peter Phillips, Judith Bender

Federal Facilities Environmental Journal • 1995

<jats:title>Abstract</jats:title><jats:p>Although for regulatory purposes, mixed waste contains both a hazardous component as well as a radioactive component, the biotreatment technology described here remediates waste in the form of organic and metal mixtures and radionuclides and mixed metals. The <jats:italic>Biomat<jats:sup>TM</jats:sup></jats:italic>, a proprietary microbial consortium, is photosynthetic, using atmospheric carbon dioxide and water to produce oxygen, and is nitrogen‐fixing (i.e., it uses atmospheric nitrogen to make usable nitrogen compounds for its growth). It contains anoxic (without oxygen) and oxic (with oxygen) zones in close proximity, which are assumed, for example, to simultaneously facilitate dechlorination and cleavage of aromatic carbon rings, respectively, in such difficult organic contaminants as PCBs and chlordane. It produces negatively charged, flocculating macromolecules which likely bind to metals.</jats:p><jats:p>The <jats:italic>Biomat<jats:sup>TM</jats:sup></jats:italic> tolerates chemical toxins and various pH, salinity, and temperature levels. In the laboratory, it has removed an array of heavy metals and metalloids, mineralized pesticides, PCB, solvents, oils, and explosives to carbon dioxide, and removed mixed waste in a continuous flow system. In the field, it has removed manganese, zinc, and other heavy metals (e.g., silver, chromium, cadmium, copper, lead, nickel, and iron) from mine drainage and BTEX, a gasoline mixture of benzene, toluene, ethylbenzene, and xylene, from contaminated groundwater. Landfill leachate is a mixture of toxic organics, metals, and ammonia. Waste Management, Inc., Microbial &amp; Aquatic Treatment Systems, Inc., and the University of Louisville are currently collaborating in a pilot project testing simultaneous remediation of leachate with the <jats:italic>Biomat<jats:sup>TM</jats:sup></jats:italic>.</jats:p>

Itziar Alkorta, Carlos Garbisu

Frontiers in Environmental Science • 0

<jats:p>The field of soil biological remediation was initially focused on the use of microorganisms. For organic contaminants, biostimulation and bioaugmentation were the strategies of choice. For heavy metals, bioremediation was centered on the feasibility of using microorganisms to reduce metal toxicity. Partly due to the impossibility to degrade metals, phytoremediation emerged proposing the use of plants to extract them (phytoextraction) or reduce their bioavailability (phytostabilization). Later, microbial-assisted phytoremediation addressed the inoculation of plant growth-promoting microorganisms to improve phytoremediation efficiency. Similarly, plant-assisted bioremediation examined the stimulatory effect of plant growth on the microbial degradation of soil contaminants. The combination of plants and microorganisms is nowadays often recommended for mixed contaminated soils. Finally, phytomanagement emerged as a phytotechnology focused on the use of plants and associated microorganisms to decrease contaminant linkages, maximize ecosystem services, and provide economic revenues. Although biological remediation methods have been in use for decades, the truth is that they have not yet yielded the expected results. Here, we claim that much more research is needed to make the most of the many ways that microorganisms have evolutionary developed to access the contaminants and to better understand the soil microbial networks responsible, to a great extent, for soil functioning.</jats:p>

Tibor Pasinszki, Melinda Krebsz

Nanomaterials • 0

<jats:p>Present and past anthropogenic pollution of the hydrosphere and lithosphere is a growing concern around the world for sustainable development and human health. Current industrial activity, abandoned contaminated plants and mining sites, and even everyday life is a pollution source for our environment. There is therefore a crucial need to clean industrial and municipal effluents and remediate contaminated soil and groundwater. Nanosized zero-valent iron (nZVI) is an emerging material in these fields due to its high reactivity and expected low impact on the environment due to iron’s high abundance in the earth crust. Currently, there is an intensive research to test the effectiveness of nZVI in contaminant removal processes from water and soil and to modify properties of this material in order to fulfill specific application requirements. The number of laboratory tests, field applications, and investigations for the environmental impact are strongly increasing. The aim of the present review is to provide an overview of the current knowledge about the catalytic activity, reactivity and efficiency of nZVI in removing toxic organic and inorganic materials from water, wastewater, and soil and groundwater, as well as its toxic effect for microorganisms and plants.</jats:p>

Alena Luptakova, Tomislav Spaldon, Magdalena Balintova

Advanced Materials Research • 0

<jats:p>The formation and treatment of acid mine drainage is the biggest environmental problems relating to mining and processing activities in the worldwide. Various methods are used for the sulphates and heavy metals removal from acid mine drainage in the world, but any of them is universal. Main aim of the paper is the interpretation of chemical and biological-chemical methods for the metals and sulphates removal from acid mine drainage sample. The chemical method is based on the sulphates precipitation by the sodium aluminate in combination with the calcium hydrate. The biological-chemical method is based on the application of sulphate-reducing bacteria (SRB). A sample of acid mine drainage from the abandoned and flooded deposit of Smolník located in Slovak republic was used in this study.</jats:p>

M. D. Ratliff

SPE Health, Safety and Environment in Oil and Gas Exploration and Production Conference • 1994

<jats:title>ABSTRACT</jats:title> <jats:p>The paper discusses two different approaches to the remediation of contaminated soil and groundwater. The information was obtained from two case studies where these methods were utilized to treat contaminants. The first approach involves the treatment of hydrocarbon-contaminated soil with microorganisms which digest the hydrocarbons releasing carbon dioxide and water. The use of microbes in this manner is commonly referred to as biotreatment. The case study was conducted in Kenai, Alaska.</jats:p> <jats:p>The second case study involved the treatment of gasoline-contaminated groundwater through the use of active permeable barrier trench systems. Trenches were installed below the surface of the groundwater and air was pumped into the groundwater, stripping the volatile hydrocarbons which were evacuated by a vapor recovery system. Because of the low hydraulic conductivity of the soil in the area, more traditional treatment options, such as the standard pump and treat operation, were not viable alternatives. The active permeable barrier trench system is being utilized at a Halliburton field facility in Artesia, New Mexico.</jats:p>

Rui C Martins, Rosa M. Quinta-Ferreira

International Journal of Chemical Reactor Engineering • 2010

<jats:p>This work deals with a real environmental problem related with milk whey wastewater. Even if a high depuration degree can be achieved using aerobic biological processes, the final effluent does not accomplish the legal regulation for disposal. In this context, we studied the application of ozone oxidation after an activated sludge treatment in order to obtain an effluent suitable to be discharged into the natural water courses. Even if the pH increase improved single ozonation efficiency, the treated wastewater was not yet able to be disposed of. The introduction of hydrogen peroxide at low concentrations enhanced the ozone action over the pollutants, and this combination led to residual water within the environmental law conditions to be released on the surroundings. Furthermore, heterogeneous catalytic ozonation over Mn-Ce-O 70/30 (prepared in our laboratory) and the commercial N-150 catalyst (Fe2O3-MnOx) was very efficient on the wastewater depuration. Nevertheless, the high amount of carbon adsorbed on the recovered catalysts disable the industrial implementation of this technology.</jats:p>

Yuan Yuan

Applied Mechanics and Materials • 0

<jats:p>Nuclear energy, due to having rich savings, great power, and less air pollution, gradually uses in civilian life widely. However, when this new energy is booming, some serious problems has appeared,such as radiation damage, the pollution of radioactive wastewater.etc .So how to make an effective protection and remediation to radiation injury has become a hot spot around the world. Here we will resport the relationship between a biological nanomaterials --Mollusk shell and the nuclear radiation, and we find that Mollusk shell not only can adsorb radionuclides, but also can repair the radiation injuries.This new function may contrubute to the design and synthesis of new radiation resistant materials.</jats:p>

Hossain Md Anawar, Rezaul Chowdhury

Sustainability • 0

<jats:p>Selection of appropriate river water treatment methods is important for the restoration of river ecosystems. An in-depth review of different river water treatment technologies has been carried out in this study. Among the physical-engineering processes, aeration is an effective, sustainable and popular technique which increases microbial activity and degrades organic pollutants. Other engineering techniques (water diversion, mechanical algae removal, hydraulic structures and dredging) are effective as well, but they are cost intensive and detrimental to river ecosystems. Riverbank filtration is a natural, slow and self-sustainable process which does not pose any adverse effects. Chemical treatments are criticised for their short-term solution, high cost and potential for secondary pollution. Ecological engineering-based techniques are preferable due to their high economic, environmental and ecological benefits, their ease of maintenance and the fact that they are free from secondary pollution. Constructed wetlands, microbial dosing, ecological floating beds and biofilms technologies are the most widely applicable ecological techniques, although some variabilities are observed in their performances. Constructed wetlands perform well under low hydraulic and pollutant loads. Sequential constructed wetland floating bed systems can overcome this limitation. Ecological floating beds are highly recommended for their low cost, high effectiveness and optimum plant growth facilities.</jats:p>

Colin Hayes, Michael Worth Calfee, Timothy Boe

Remediation Journal • 2023

<jats:title>Abstract</jats:title><jats:p>Large‐scale biological contamination incidents pose unique yet significant challenges to remediation operations. Previous incidents have demonstrated the utility of readily available commercial and municipal equipment for conducting remediation tasks. Preidentification and evaluation of such equipment could reduce lag time for response initiation and enhance overall response effectiveness and efficiency. The current study aimed to identify commercial and municipal equipment that could be beneficial in wide‐area biological remediation operations. Equipment were identified by market research, their utility was assessed by a group of subject matter experts, and a subset of those equipment was observed under operational conditions in a realistic urban environment. Observations and feedback from demonstration participants are presented within the article. This information is intended to support rapid decision‐making following large‐scale biological incidents, broaden the universe of potentially useful equipment to support the response, enhance response operations, and reduce the impact on the public.</jats:p>

Melissa Schmitt, Srinivasa Varadhan, Sandra Dworatzek et al.

Remediation Journal • 2017

<jats:title>Abstract</jats:title><jats:p>Laboratory and field demonstration studies were conducted to assess the efficacy of enhanced biological reduction of 1,2,3‐trichloropropane (TCP) in groundwater. Laboratory studies evaluated the effects of pH and initial TCP concentrations on TCP reduction and the activity of a microbial inoculum containing <jats:italic>Dehalogenimonas</jats:italic> (<jats:italic>Dhg</jats:italic>). Laboratory results showed successful reduction at a pH of 5 to 9 with optimal reduction at 7 to 9 and at initial TCP concentrations ranging from 10 to over 10,000 micrograms per liter (μg/L). Based on findings from the laboratory study, the effects of TCP concentration, geochemical conditions, and amendment concentration on bioremediation efficacy were investigated during a field demonstration at a site with relatively low initial concentrations of TCP (&lt; 2 μg/L). The field demonstration included injection of emulsified vegetable oil (EVO) and lactate as a carbon substrate for biostimulation, followed by bioaugmentation using the microbial inoculum containing <jats:italic>Dhg</jats:italic>. Post‐injection performance monitoring demonstrated reduction of TCP to below laboratory detection limits (&lt; 0.005 μg/L) after an initial lag period of approximately six months following injections. TCP reduction was accompanied by generation of the degradation byproduct propene. A marginal increase in TCP concentrations, potentially due to an influx of upgradient aerobic groundwater containing TCP, was observed eight months after injections thereby demonstrating the sensitivity of this bioaugmentation application to changes in geochemical parameters. Despite this marginal increase, performance monitoring results indicate continued TCP biodegradation 15 months after implementation of the injection program. This demonstration suggests that enhanced biodegradation of TCP by combining biostimulation and bioaugmentation may be a promising solution to the challenges associated with remediation of TCP, even when present at low part per billion concentrations in groundwater.</jats:p>

Patrick M. Woodhull, Douglas E. Jerger

Remediation Journal • 1994

<jats:title>Abstract</jats:title><jats:p>Slurry‐phase bioremediation is an engineered process for treating contaminated soils or sludges. Slurry‐phase biological treatment can be applied to a variety of contaminated wastes amenable to microbial degradation, including manufactured gas plant wastes, wood‐treating wastes, refinery wastes, petroleum hydrocarbons, and select chlorinated compounds, including PCBs. This article describes the process by which a commercial slurry‐phase treatment system was used to bioremediate contaminants at two sites–a wood treatment facility and a manufactured gas plant. A process description of the system and an analysis of project costs are provided.</jats:p><jats:p>Bioremediation offers two advantages over other remediation alternatives: on‐site destruction of the contaminant(s) and lower total remedial costs. Slurry‐phase biological treatment offers several advantages over conventional bioremediation technologies (i.e., land treatment). Slurry‐phase biological treatment can achieve increased degradation rates, higher treatment efficiencies, greater control of environmental and operating conditions, and smaller treatment area requirements. Slurry‐phase biological treatment costs range from approximately $200 to $230 per cubic yard, which is comparable to other on‐site remediation technologies.</jats:p>

, Shahzad Ali

Indian Journal of Pure &amp; Applied Biosciences • 0

<jats:p>Such elements have an atomic density of more than 4g/cm3 or 5 times or more than water is heavy metals, i.e. Nical (Ni), silver (Ag), cobalt (Co), iron (Fe), manganese (Mn), lead (Pb), arsenic (As) and cadmium (Cd). In these, some are essential, i.e. iron (Fe), zinc (Zn), copper (Cu), manganese (Mn), molybdenum (Mo) and Nical (Ni). Rapid increments in industry, agriculture, and urbanization produce non-degradable toxic materials, i.e. heavy metals. Heavy metals are also produced by natural resources but higher values reflect anthropogenic accumulation. Soil is one of the valuable, essential, non-regenerative resources. Many soil properties, i.e. pH, organic contents, ion exchange capacity, texture, microbial growth, microbial density or metabolic processes, are deteriorated by the heavy metals accumulation. Heavy metals are a non-degradable part of the soil environment. Soil remediation is necessary due to high productive pressure with food security concerns. Different Physico-chemical and biological practices are in practice to remediate the soil environment. Mainly use of amendments (liming material, organic contents and adequate fertilizer rate) and plants (phytoremediation and phytodegration) are the most economical cost-effective and environmentally well-sounded techniques for cleanup of the soil environment. Amendments help to reclaim the soil's Physico-chemical properties, microbial community establishment and bond different heavy metals to reduce their mobility. Prevention of the entry of heavy metals into the food chain is a major goal of phytoremediation. Physical with genetic engineering approaches must be practiced to make new genetically controlled plants used in future prospects to remediate the soil.</jats:p>

Sanjoy K. Bhattacharya

Remediation Journal • 1992

<jats:title>Abstract</jats:title><jats:p>Because bioremediation must satisfy the fundamental biological tastes of specific organisms, environmental engineers must create a nutritious waste stew. Waste‐hungry organisms need a proper electron acceptor. Oxygen is preferred; if it is not available, nitrate, sulfate, or carbon dioxide may work. The waste itself is a source of carbon and energy. Macronutrients are next—including phosphorus, nitrogen, and certain metals, if they are not already present in the wastewater—as well as micronutrients. Other factors, including pH, temperature, aeration, and mixing must suit the organisms' natural temperaments. This article explores how bioengineers can combine these ingredients in precise quantities and proportions in both conventional and innovative aerobic and anaerobic bioprocesses, including in situ treatment and even composting, to make the organisms healthy, happy, and inexpensive.</jats:p>

Xue-ling Wu, Yichao Gu, Xiao-yan Wu et al.

Microorganisms • 2020

As an environmental pollutant, tetracycline (TC) can persist in the soil for years and damage the ecosystem. So far, many methods have been developed to handle the TC contamination. Microbial remediation, which involves the use of microbes to biodegrade the pollutant, is considered cost-efficient and more suitable for practical application in soil. This study isolated several strains from TC-contaminated soil and constructed a TC-degrading bacterial consortium containing Raoultella sp. XY-1 and Pandoraea sp. XY-2, which exhibited better growth and improved TC degradation efficiency compared with single strain (81.72% TC was biodegraded within 12 days in Lysogeny broth (LB) medium). Subsequently, lab-scale soil remediation was conducted to evaluate its effectiveness in different soils and the environmental effects it brought. Results indicated that the most efficient TC degradation was recorded at 30 °C and in soil sample Y which had relatively low initial TC concentration (around 35 mg/kg): TC concentration decreased by 43.72% within 65 days. Soil properties were affected, for instance, at 30 °C, the pH value of soil sample Y increased to near neutral, and soil moisture content (SMC) of both soils declined. Analysis of bacterial communities at the phylum level showed that Proteobacteria, Bacteroidetes, Acidobacteria, and Chloroflexi were the four dominant phyla, and the relative abundance of Proteobacteria significantly increased in both soils after bioremediation. Further analysis of bacterial communities at the genus level revealed that Raoultella sp. XY-1 successfully proliferated in soil, while Pandoraea sp. XY-2 was undetectable. Moreover, bacteria associated with nitrogen cycling, biodegradation of organic pollutants, soil biochemical reactions, and plant growth were affected, causing the decline in soil bacterial diversity. Variations in the relative abundance of tetracycline resistance genes (TRGs) and mobile gene elements (MGEs) were investigated, the results obtained indicated that tetD, tetG, tetX, intI1, tnpA-04, and tnpA-05 had higher relative abundance in original soils, and the relative abundance of most TRGs and MGEs declined after the microbial remediation. Network analysis indicated that tnpA may dominate the transfer of TRGs, and Massilia, Alkanibacter, Rhizomicrobium, Xanthomonadales, Acidobacteriaceae, and Xanthomonadaceae were possible hosts of TRGs or MGEs. This study comprehensively evaluated the effectiveness and the ecological effects of the TC-degrading bacterial consortium in soil environment.

R. Ammeri, W. Hassen, Y. Hidri et al.

International Journal of Phytoremediation • 2021

Abstract This study has contributed in the description of bioaugmentation-phytoremediation efficiency process using Typha angustifolia concerning PCP tolerance and removal from wastewater. Samples of wastewater were collected from industrial wastewater plants, namely row wastewater effluent “E.WW”, primary wastewater “P.WW”, secondary wastewater “S.WW”, clarified wastewater “AC.WW”. These effluents were spiked with PCP at different rate (100, 500, and 1000 mg.L−1), physical, chemical and biological properties were monitored. A second experiment was set up in order to check the efficiency of phytoremediation treatments of the different effluents artificially contaminated with 200 mg.L−1 PCP after 20 days lab scale experiment. An important PCP removal by indigenous bacteria was showed in S. WW with values from 1000 to 72.2 mg.L−1 from T0 (start of the experiment) to TF (end of the experiment), respectively. Phytoremediation process allowed a decrease of PCP rate from 200 to 6.4 mg.L−1, a decrease of chloride content from 14.0 to 4.0 mg.L−1 in S.WW samples was observed. Furthermore, a significant increase of bacterial number in S.WW and AC.WW to 1.700 × 106 and 1.450 × 106 CFU.mL−1, respectively was observed. In addition, the DGGE analysis showed that after bioaugmentation-phytoremediation treatments, the highest species richness and relative abundance in wastewater effluent was observed. Novelty statement Pentachlorophenol (PCP) is one of highly toxic of polychlorophenols and required to continuously monitor in environment. This paper presenting a sensitive method phytoremediation and bioaugmentation for PCP biotransformation in wastewater. The novelty is the choice of a macrophyte Typha angustifolia, which is still used for the elimination of heavy metals but it not used for pesticide and pollutant removal in wastewater. Also, there are different analysis that was performed in order to check phyto-technique process (DGGE and HPLC). On the other side, in this study, the phyto-techniques with Typha angustifolia positively affected intrinsic microorganisms in order to promote pollutant remediation. So, the intrinsic microorganisms in wastewater with the macrophyte presence have a great capacity to reduce this pollutant and improve the bioremediation process.

Jin-wook Kim, Y. Hong, H. Kim et al.

Toxics • 2021

Soil washing and landfarming processes are widely used to remediate total petroleum hydrocarbon (TPH)-contaminated soil, but the impact of these processes on soil bacteria is not well understood. Four different states of soil (uncontaminated soil (control), TPH-contaminated soil (CS), after soil washing (SW), and landfarming (LF)) were collected from a soil remediation facility to investigate the impact of TPH and soil remediation processes on soil bacterial populations by metagenomic analysis. Results showed that TPH contamination reduced the operational taxonomic unit (OTU) number and alpha diversity of soil bacteria. Compared to SW and LF remediation techniques, LF increased more bacterial richness and diversity than SW, indicating that LF is a more effective technique for TPH remediation in terms of microbial recovery. Among different bacterial species, Proteobacteria were the most abundant in all soil groups followed by Actinobacteria, Acidobacteria, and Firmicutes. For each soil group, the distribution pattern of the Proteobacteria class was different. The most abundant classed were Alphaproteobacteria (16.56%) in uncontaminated soils, Deltaproteobacteria (34%) in TPH-contaminated soils, Betaproteobacteria (24%) in soil washing, and Gammaproteobacteria (24%) in landfarming, respectively. TPH-degrading bacteria were detected from soil washing (23%) and TPH-contaminated soils (21%) and decreased to 12% in landfarming soil. These results suggest that soil pollution can change the diversity of microbial groups and different remediation techniques have varied effective ranges for recovering bacterial communities and diversity. In conclusion, the landfarming process of TPH remediation is more advantageous than soil washing from the perspective of bacterial ecology.

A. Castaño, A. Prosenkov, D. Baragaño et al.

Frontiers in Microbiology • 2021

Nanoscale Zero-Valent Iron (nZVI) is a cost-effective nanomaterial that is widely used to remove a broad range of metal(loid)s and organic contaminants from soil and groundwater. In some cases, this material alters the taxonomic and functional composition of the bacterial communities present in these matrices; however, there is no conclusive data that can be generalized to all scenarios. Here we studied the effect of nZVI application in situ on groundwater from the site of an abandoned fertilizer factory in Asturias, Spain, mainly polluted with arsenic (As). The geochemical characteristics of the water correspond to a microaerophilic and oligotrophic environment. Physico-chemical and microbiological (cultured and total bacterial diversity) parameters were monitored before and after nZVI application over six months. nZVI treatment led to a marked increase in Fe(II) concentration and a notable fall in the oxidation-reduction potential during the first month of treatment. A substantial decrease in the concentration of As during the first days of treatment was observed, although strong fluctuations were subsequently detected in most of the wells throughout the six-month experiment. The possible toxic effects of nZVI on groundwater bacteria could not be clearly determined from direct observation of those bacteria after staining with viability dyes. The number of cultured bacteria increased during the first two weeks of the treatment, although this was followed by a continuous decrease for the following two weeks, reaching levels moderately below the initial number at the end of sampling, and by changes in their taxonomic composition. Most bacteria were tolerant to high As(V) concentrations and showed the presence of diverse As resistance genes. A more complete study of the structure and diversity of the bacterial community in the groundwater using automated ribosomal intergenic spacer analysis (ARISA) and sequencing of the 16S rRNA amplicons by Illumina confirmed significant alterations in its composition, with a reduction in richness and diversity (the latter evidenced by Illumina data) after treatment with nZVI. The anaerobic conditions stimulated by treatment favored the development of sulfate-reducing bacteria, thereby opening up the possibility to achieve more efficient removal of As.

C. Campillo-Cora, D. Soto-Gómez, M. Arias-Estévez et al.

Agronomy • 2022

The assessment of remediation on metal-polluted soils is usually focused on total and/or bioavailable metal content. However, these chemical variables do not provide direct information about reductions in heavy metals pressure on soil microorganisms. We propose the use of bacterial communities to evaluate the efficiency of three remediation techniques: crushed mussel shell (CMS) and pine bark (PB) as soil amendments and EDTA-washing. A soil sample was polluted with different doses of Cu, Ni, and Zn (separately). After 30 days of incubation, the remediation techniques were applied, and bacterial community tolerance to heavy metals determined. If bacterial communities develop tolerance, it is an indicator that the metal is exerting toxicity on them. Soil bacterial communities developed tolerance to Cu, Ni, and Zn in response to metal additions. After remediation, bacterial communities showed decreases in bacterial community tolerance to Cu, Ni, and Zn for all remediation techniques. For Cu and Ni, soil EDTA-washing showed the greatest reduction of bacterial community tolerance to Cu and Ni, respectively, while for Zn the soil amendment with PB was the most effective remediation technique. Thus, bacterial community tolerance to heavy metals successfully detect differences in the effectiveness of the three remediation techniques.

N. Agarwal, V. S. Solanki, A. Gacem et al.

Water • 2022

Biological treatment methods for the biodegradation of anthropogenic toxic pollutants are eco-friendly in nature and are powered by a variety of microbial enzymes. Green chemistry and enzymes play a crucial role in catalyzing the biodegradation of organic and inorganic pollutants including azo dyes; polyaromatic hydrocarbons; lead; organic cyanides; aromatic amines; mono-, di-, and polyphenols; polymers; and mercury. Laccases form a prospective group of multifunctional oxidoreductase enzymes with great potential for oxidizing different categories of organic and inorganic pollutants and their diversified functions, such as pigment formation, lignin degradation, and detoxification of industrial wastes including xenobiotics mainly from the pharmaceutical, paper textile, and petrochemical industries. Therefore, it is very important to study laccases as green and environmentally friendly alternatives for the degradation of xenobiotics. This review article will cover comprehensive information about the functions and properties of bacterial laccases for a deep understanding of their scope and applications for effective bioremediation of recalcitrant xenobiotics.

Zhong-Fei Xue, W. Cheng, Lin Wang et al.

Frontiers in Bioengineering and Biotechnology • 2022

Lead and copper ions from wastewater induced by metallurgical processes are accumulated in soils, threatening plant and human health. The bioinspired calcium carbonate precipitation is proven effective in improving the cementation between soil particles. However, studies on capsulizing heavy metal ions using the bioinspired calcium carbonate precipitation are remarkably limited. The present study conducted a series of test tube experiments to investigate the effects of bacterial culture and calcium source addition on the remediation efficiency against lead and copper ions. The calcium carbonate precipitation was reproduced using the Visual MINTEQ software package to reveal the mechanism affecting the remediation efficiency. The degradation in the remediation efficiency against lead ions relies mainly upon the degree of urea hydrolysis. However, higher degrees of urea hydrolysis cause remediation efficiency against copper ions to reduce to zero. Such high degree of urea hydrolysis turns pH surrounding conditions into highly alkaline environments. Therefore, pursuing higher degrees of urea hydrolysis might not be the most crucial factor while remedying copper ions. The findings shed light on the importance of modifying pH surrounding conditions in capsulizing copper ions using the bioinspired calcium carbonate precipitation.

Xiaoyun Chai, Mutian Wang, Xiaowen Fu et al.

Frontiers in Environmental Science • 2023

Introduction: Bioremediation has been shown to be an effective strategy for removing toxic pollutants from the environment, particularly organic chemicals such as petroleum hydrocarbons. This paper investigates the changes in toxicity of petroleum-contaminated soil as a result of microbial remediation processes. Methods: Changes in the ecotoxicity of the contaminated soil were examined using a plant, earthworm, enzyme activity and luminescent bacteria toxicity tests. Results: The results showed that bioremediation could effectively degrade petroleum hydrocarbon (C10–C40) pollutants. After 42 days of remediation, the petroleum hydrocarbon (C10–C40) content of Group A (bioaugmented polluted wetland soil) decreased from 1.66 g/kg to 1.00 g/kg, and the degradation rate was 40.6%. The petroleum hydrocarbon (C10–C40) content of Group B (bioaugmented polluted farmland soil decreased from 4.00 g/kg to 1.94 g/kg, and the degradation rate was 51.6%. During the microbial remediation progress, the ecological toxicity of petroleum-contaminated soil first increased and then decreased. The photosynthetic pigment content index in the higher plant toxicity test, the earthworm survival index and the soil catalase activity all showed good agreement with the relative luminescence index of extracted DCM/DMSO in the luminescent bacterial toxicity test. The soil toxicity decreased significantly after remediation. Specifically, the photosynthetic pigment content of wheat were inhibited in the soil during the whole process (remediation for 42 days), and decreased to the minimum on remediation day 21. The 7-day and 14-day survival rate of earthworms in Group A and Group B gradually decreased in the soil remediation process, and then gradually increased, survival rate at the end of remediation was higher than at the beginning. Soil catalase activity was significantly negatively correlated with petroleum hydrocarbon (C10–C40) content (−0.988, −0.989). The ecological toxicity of contaminated soil reached to the maximum on the 21st day of remediation, relative luminosity of luminescent bacteria in dichloromethane/dimethyl sulfoxide extracts from Group A and Group B were 26.3% and 16.3%, respectively. Conclusion: Bioremediation could effectively degrade petroleum hydrocarbon (C10–C40) pollutants. Wheat photosynthetic pigment content, earthworm survival rate, soil catalase activity and relative luminescence of luminescent bacteria can better indicate the ecological toxicity of petroleum-contaminated soil in bioremediation process.

Dongchu Guo, Zhouzhou Fan, Shuyu Lu et al.

Scientific Reports • 0

<jats:title>Abstract</jats:title><jats:p>Mining and smelting activities are the major sources of antimony (Sb) contamination. The soil around Xikuangshan (XKS), one of the largest Sb mines in the world, has been contaminated with high concentrations of Sb and other associated metals, and has attracted extensive scholarly attention. Phytoremediation is considered a promising method for removing heavy metals, and the diversity and structure of rhizosphere microorganisms may change during the phytoremediation process. The rhizosphere microbiome is involved in soil energy transfer, nutrient cycling, and resistance and detoxification of metal elements. Thus, changes in this microbiome are worthy of investigation using high-throughput sequencing techniques. Our study in Changlongjie and Lianmeng around XKS revealed that microbial diversity indices in the rhizospheres of <jats:italic>Broussonetia papyrifera</jats:italic> and <jats:italic>Ligustrum lucidum</jats:italic> were significantly higher than in bulk soil, indicating that plants affect microbial communities. Additionally, most of the bacteria that were enriched in the rhizosphere belonged to the Proteobacteria, Acidobacteria, Actinobacteria, and Bacteroidetes. In Changlongjie and Lianmeng, the diversity and abundance of the microbial community in the <jats:italic>B</jats:italic>. <jats:italic>papyrifera</jats:italic> rhizosphere were higher than in <jats:italic>L</jats:italic>. <jats:italic>lucidum</jats:italic>. In parallel, the soil pH of the <jats:italic>B</jats:italic>. <jats:italic>papyrifera</jats:italic> rhizosphere increased significantly in acidic soil and decreased significantly in near-neutral soil. Redundancy analyses indicated that pH was likely the main factor affecting the overall bacterial community compositions, followed by moisture content, Sb, arsenic (As), and chromium (Cr).</jats:p>

Paul Bardos

Remediation Journal • 2014

<jats:p>In the past decade or so, management of historically contaminated land has largely been based on prevention of unacceptable risks to human health and the environment, to ensure a site is “fit for use” (i.e., achieves suitability for beneficial uses). More recently, interest has been shown in including sustainability as a decision‐making criterion. Sustainability concerns include the environmental, social, and economic consequences of risk‐management activities themselves, and also the opportunities for wider benefit beyond achieving risk‐reduction goals alone. This article provides a global roundup of progress by these initiatives and their key documentation. It reviews common themes and points of divergence. The information is based on a literature review and surveying the various networks involved, with a particular focus on recent developments in the United Kingdom. The global roundup updates a previous global roundup presented in Europe in 2013 at Aquaconsoil 2013 (Bardos et al., 2013a, 2013b). © 2014 Paul Bardos</jats:p>

Paul Nathanail

Remediation Journal • 2011

<jats:title>Abstract</jats:title><jats:p>Sustainable remediation is at a crossroads. In a few short years it has become a mainstream topic while simultaneously maintaining its chimeral status. Sustainable remediation is a term claimed by many yet a concept apparently understood by few. Its characterization has necessitated the development of a plethora of metrics and tools yet its essence readily emerges. U.S.‐led initiatives have been adopted around the globe. Relative sustainability appraisal is easy to carry out and potentially sufficient for most site circumstances. The need to adequately protect human health and the environment has been recognized. Now the industry needs to focus our attention on protection and restoration that itself has a reasonably maximized net benefit. © 2011 Wiley Periodicals, Inc.</jats:p>

Paul W. Hadley, Melissa Harclerode

Remediation Journal • 2015

<jats:p>Different points of view have emerged concerning how to best consider and address the largely unexamined ancillary environmental impacts, and more particularly the social and economic impacts, of remediation activities. These views are generally categorized as “green remediation” and “sustainable remediation.” This article dissects the commonalities and differences between “green” and “sustainable” remediation approaches. Several key obstacles to the broader implementation of sustainable remediation practices are identified. Similarities identified among the two concepts offer a common ground and areas of collaboration. The objective of this article is to support maturation of the remediation industry by addressing the opposition to and supporting the implementation of sustainable remediation practices, including offering recommendations for a path forward. ©2015 Wiley Periodicals, Inc.</jats:p>

Yongqi Zhu, Mengjie An, Tumur Anwar et al.

Frontiers in Microbiology • 0

<jats:sec><jats:title>Introduction</jats:title><jats:p>Heavy metal pollution is a major worldwide environmental problem. Many remediation techniques have been developed, these techniques have different performance in different environments.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>In this study, soil sampling was conducted in multiple cotton fields in Xinjiang, China, and found that cadmium (Cd) was the most abundant soil heavy metal. Then, to find the most suitable technique for the remediation of Cd pollution in cotton fields, a two-year study was conducted to explore the effects of cotton straw-derived biochar (BC, 3%) and <jats:italic>Bacillus</jats:italic>-based biofertilizer (BF, 1.5%) on cotton Cd uptake and transport and soil microbial community structure under Cd exposure conditions (soil Cd contents: 1, 2, and 4 mg·kg<jats:sup>−1</jats:sup>).</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>The results showed that the bioaccumulation coefficients (Cd content of cotton organs / soil available Cd content) of cotton roots, stems, leaves, and buds/bolls reduced by 15.93%, 14.41%, 23.53%, and 20.68%, respectively after the application of BC, and reduced by 16.83%, 17.15%, 22.21%, and 26.25%, respectively after the application of BF, compared with the control (no BC and BF). Besides, the application of BC and BF reduced the transport of Cd from soil to root system, and enhanced the diversity of soil bacterial communities (dominant species: <jats:italic>Alphaproteobacteria</jats:italic> and <jats:italic>Actinobacteria</jats:italic>) and the metabolic functions related to amino acid synthesis. It was worth noting that the differential species for BF group <jats:italic>vs</jats:italic> BC group including <jats:italic>Alphaproteobacteria</jats:italic>, <jats:italic>Gemmatimonadetes</jats:italic>, <jats:italic>Bacilli</jats:italic>, and <jats:italic>Vicinamibacteria</jats:italic> were associated with the enrichment and transport of Cd, especially the transport of Cd from cotton roots to stems.</jats:p></jats:sec><jats:sec><jats:title>Discussion</jats:title><jats:p>Therefore, the application of BC and BF changed the soil bacterial diversity in Cd-polluted cotton field, and then promoted the transport of Cd in cotton, ultimately improving soil quality. This study will provide a reference for the selection of soil heavy metal pollution remediation techniques in Xinjiang, China.</jats:p></jats:sec>

Ting Wang, Hongwen Sun, Xinhao Ren et al.

Scientific Reports • 0

<jats:title>Abstract</jats:title><jats:p>Two kinds of biochars, one derived from corn straw and one from pig manure, were studied as carriers of a mutant genotype from <jats:italic>Bacillus subtili</jats:italic>s (B38) for heavy metal contaminated soil remediation. After amendment with biochar, the heavy metal bioavailability decreased. Moreover, the heavy metal immobilization ability of the biochar was enhanced by combining it with B38. The simultaneous application of B38 and pig manure-derived biochar exhibited a superior effect on the promotion of plant growth and the immobilization of heavy metals in soil. The plant biomass increased by 37.9% and heavy metal concentrations in the edible part of lettuce decreased by 69.9–96.1%. The polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) profiles revealed that pig manure-derived biochar could enhance the proliferation of both exotic B38 and native microbes. These results suggest that B38 carried by pig manure-derived biochar may be a promising candidate for the remediation of soils contaminated by multiple heavy metals.</jats:p>

S.T. Azeko, O.S. Odusanya, K. Malatesta et al.

Advanced Materials Research • 0

<jats:p>Improper disposal of commodity plastics such as polyethylene (PE) in the environment causes land pollution and soil infertility. It is unsightly and strongly threatens plant and animal life. The current effort describes the bacteria-mediated biodegradation of polyethylene by<jats:italic>Serratia marcescens marcescens</jats:italic>(<jats:italic>SM</jats:italic>) without prior exposure to thermo-oxidative aging. This study further describes the mechanism involved in the biodegradation of PE, in which a carbonless medium containing essential minerals and vitamins and powdered PE, were placed in the presence of overnight cultures of<jats:italic>SM.</jats:italic>The samples were incubated at 30°C, centrifuged at a speed of 141 revolutions per minute (rpm) in a rotary shaker for ten weeks in order to observe the degradation process. The effects of cell-free supernatants (from the<jats:italic>SM</jats:italic>cultures) upon the degradation of sterile PE are elucidated. The results show that the supernatants from<jats:italic>SM</jats:italic>degrade PE faster than the bacteria, with a 37.5 percent of degradation rate within a month. The SEM micrographs suggest that the biodegradation of polyethylene involves the formation and coalescence of microvoids. The DSC results revealed that the feeding activity of SM is mostly favored at the crystalline region due to its high energy.</jats:p>

Uloma Linda Nwaehiri, Peter Ikechukwu Akwukwaegbu, Bertram Ekejiuba Bright Nwoke

Environmental Analysis Health and Toxicology • 0

<jats:p>Bacterial remediation of heavy metal polluted soil and effluent from paper mill was investigated using standard analytical methods. The paper mill was visited for 6 months at interval of 30 days to collect soil and effluent samples for the analysis. The pH of soil was slightly alkaline while effluent was acidic. There was a significant increase (P &lt; 0.05) in total organic carbon (TOC) of soil; and turbidity, biochemical oxygen demand (BOD), chemical oxygen demand (COD) and TOC of effluent when compared to control. Bacteria isolated from the samples were grouped into two and used to remediate eight heavy metals. The remediation experiment consists of three treatments; Treatment 1 (treated with proteobacteria), Treatment 2 (treated with non-proteobacteria) and Treatment 3 (without bacteria) (control experiment). Result of the remediation study showed that there was a significant decrease (P &lt; 0.05) in Treatment 1 and Treatment 2 of all the heavy metals in soil and effluent samples from day 30-180 when compared to day 0. The rate of removal of heavy metals in soil was highest in Treatment 1 for chromium (Cr; 0.00846 day-1) and lowest in Treatment 1 for cadmium (Cd; 0.00403 day-1) while the rate of removal in effluent was highest in Treatment 1 for zinc (Zn; 0.01207 day-1) and lowest in Treatment 1 for Cd (0.00391 day-1). It was concluded that bacteria isolated from soil and effluent samples were capable of remediating the concentration of Pb, arsenic (As), Cr, Zn and nickel (Ni) heavy metals.</jats:p>

Ali Firoozi, Ali Asghar Firoozi

New Environmentally-Friendly Materials • 0

<jats:p>Ground contamination poses significant environmental and health challenges globally. Traditional remediation methods, while effective, have often resulted in secondary environmental issues. In light of this, there has been a distinct shift towards more sustainable solutions. This study delves into the potential of three environmentally friendly materials, namely plant fibers, green stones, and anti-bacterial substances, as viable tools for ground remediation. Simulated scenarios, representing industrial, agricultural, and urban landfill contaminations, were employed to assess the efficacy of these materials. Results suggest that each material has a unique potential to address specific contamination types, underpinning their value in a comprehensive, eco-conscious ground remediation strategy.</jats:p>

Qian Wang, Xinhua Xu, Fanglin Zhao et al.

Water Science and Technology • 2010

<jats:p>Chromium(VI) is a priority pollutant in soils and wastewaters and reduction of Cr(VI) to Cr(III) is a solution to this problem. In this study a low-cost method was proposed to adapt indigenous bacteria and use them to reduce Cr(VI) in solutions. The experiment results show that Cr(VI) could be efficiently reduced by indigenous bacteria under anaerobic and pH-unadjusted conditions. After about 24 h the concentration of Cr(VI) could be reduced from 21.74 mg/L to below 0.5 mg/L. The observed Cr(VI) reduction rates were affected by temperature and pH. Cr(VI) in aqueous solutions could be reduced to Cr(III) completely and partly be incepted by the organisms. Cr(VI) reduction was enzyme-mediated. It was not an energy-conserving process but a detoxification reaction. This method could be used in an anaerobic reactor to treat low-concentration wastewater or industrial water as the last step.</jats:p>

Jamilu E. Ssenku, Abdul Walusansa, Hannington Oryem-Origa et al.

BMC Microbiology • 0

<jats:title>Abstract</jats:title><jats:sec> <jats:title>Background</jats:title> <jats:p>Oil spills are ranked among the greatest global challenges to humanity. In Uganda, owing to the forthcoming full-scale production of multi-billion barrels of oil, the country’s oil pollution burden is anticipated to escalate, necessitating remediation. Due to the unsuitability of several oil clean-up technologies, the search for cost-effective and environmentally friendly remediation technologies is paramount. We thus carried out this study to examine the occurrence of metabolically active indigenous bacterial species and chemical characteristics of soils with a long history of oil pollution in Uganda that can be used in the development of a bacterial-based product for remediation of oil-polluted sites.</jats:p> </jats:sec><jats:sec> <jats:title>Results</jats:title> <jats:p>Total hydrocarbon analysis of the soil samples revealed that the three most abundant hydrocarbons were pyrene, anthracene and phenanthrene that were significantly higher in oil-polluted sites than in the control sites. Using the BIOLOG EcoPlate™, the study revealed that bacterial species richness, bacterial diversity and bacterial activity (ANOVA, <jats:italic>p</jats:italic> &lt; 0.05) significantly varied among the sites. Only bacterial activity showed significant variation across the three cities (ANOVA, <jats:italic>p</jats:italic> &lt; 0.05). Additionally, the study revealed significant moderate positive correlation between the bacterial community profiles with Zn and organic contents while correlations between the bacterial community profiles and the hydrocarbons were largely moderate and positively correlated.</jats:p> </jats:sec><jats:sec> <jats:title>Conclusions</jats:title> <jats:p>This study revealed largely similar bacterial community profiles between the oil-polluted and control sites suggestive of the occurrence of metabolically active bacterial populations in both sites. The oil-polluted sites had higher petroleum hydrocarbon, heavy metal, nitrogen and phosphorus contents. Even though we observed similar bacterial community profiles between the oil polluted and control sites, the actual bacterial community composition may be different, owing to a higher exposure to petroleum hydrocarbons. However, the existence of oil degrading bacteria in unpolluted soils should not be overlooked. Thus, there is a need to ascertain the actual indigenous bacterial populations with potential to degrade hydrocarbons from both oil-polluted and unpolluted sites in Uganda to inform the design and development of a bacterial-based oil remediation product that could be used to manage the imminent pollution from oil exploration and increased utilization of petroleum products in Uganda.</jats:p> </jats:sec>

Sweta Parimita Bera, Maulin P. Shah, Manoj Godhaniya

Frontiers in Environmental Science • 0

<jats:p>Textile effluent generated during the dyeing process of textiles is a huge supplier to water toxicity all over the world. Textile dyes are the main toxic component found in the effluent sample which is difficult to treat. A bacterial consortium capable of decolourizing and degrading the textile dye acid orange is reported in this research article. The bacterial consortium was identified by 16 S rDNA sequence and phenotypic characteristics. It is composed of four strains i.e., <jats:italic>Pseudomonas stutzeri</jats:italic> (MW219251), <jats:italic>Bacillus tequilensis</jats:italic> (MW110471), <jats:italic>Bacillus flexus</jats:italic> (MW131645), <jats:italic>Kocuria rosea</jats:italic> (MW132411). The consortium was able to cause decolorization of azo dye acid orange (30 mg/L) in 23 h, when kept under static laboratory conditions. The optimal pH and temperature for color removal were pH 7.5 and 32°C, respectively. The decolorization of dye before and after was checked by UV-Visible absorption spectra. This gives evidence that decolorization was caused due to biodegradation. This was further assured by studying the reduction of biological oxygen demand (BOD<jats:sub>5</jats:sub> (96%), chemical oxygen demand (COD) (79%), and TOC (total organic carbon) (54%) of the bacterial-treated water sample. The Fourier transform-infrared spectroscopy (FT-IR) spectroscopy and gas chromatography-mass spectroscopy (GC-MS) results confirmed the mineralization of the dye. The results indicate the effectiveness of the bacterial consortium SPB92 in the biodegradation of acid orange dye. This demonstrates that the consortium has immense potential and will serve as an important contributor to the treatment of textile wastewater.</jats:p>

Uriel Fernando Carreño Sayago, Vladimir Ballesteros Ballesteros, Angelica María Lozano Aguilar

Polymers • 0

<jats:p>The search for adsorbents that are non-toxic and low cost with a high adsorption capacity and excellent recyclability is a priority to determine the way to reduce the serious environmental impacts caused by the discharge of effluents loaded with heavy metals. Bacterial cellulose (BC) biomass has functional groups such as hydroxyl and carbonyl groups that play a crucial role in making this cellulose so efficient at removing contaminants present in water through cation exchange. This research aims to develop an experimental process for the adsorption, elution, and reuse of bacterial cellulose biomass in treating water contaminated with Cr (VI). SEM images and the kinetics behavior were analyzed with pseudo-first- and pseudo-second-order models together with isothermal analysis after each elution and reuse process. The adsorption behavior was in excellent agreement with the Langmuir model along with its elution and reuse; the adsorption capacity was up to 225 mg/g, adding all the elution processes. This study presents a novel approach to the preparation of biomass capable of retaining Cr (VI) with an excellent adsorption capacity and high stability. This method eliminates the need for chemical agents, which would otherwise be difficult to implement due to their costs. The viability of this approach for the field of industrial wastewater treatment is demonstrated.</jats:p>

Jun Hirose

Microorganisms • 0

<jats:p>Integrative and conjugative elements (ICEs) are mobile DNA molecules that can be transferred through excision, conjugation, and integration into chromosomes. They contribute to the horizontal transfer of genomic islands across bacterial species. ICEs carrying genes encoding aromatic compound degradation pathways are of interest because of their contribution to environmental remediation. Recent advances in DNA sequencing technology have increased the number of newly discovered ICEs in bacterial genomes and have enabled comparative analysis of their evolution. The two different families of ICEs carry various aromatic compound degradation pathway genes. ICEclc and its related ICEs contain a number of members with diverse catabolic capabilities. In addition, the Tn4371 family, which includes ICEs that carry the chlorinated biphenyl catabolic pathway, has been identified. It is apparent that they underwent evolution through the acquisition, deletion, or exchange of modules to adapt to an environmental niche. ICEs have the property of both stability and mobility in the chromosome. Perspectives on the use of ICEs in environmental remediation are also discussed.</jats:p>

Clayton L. Rugh, Scott A. Merkle, Richard B. Meagher

HortScience • 1996

<jats:p>The use of plants to stabilize, reduce, or detoxify aquatic and terrestrial pollution is known as phytoremediation. We have employed a molecular genetic approach for the development of potentially phytoremediative species using a bacterial gene for ionic mercury detoxification. One gene of the bacterial mercury resistance operon, <jats:italic>merA</jats:italic>, codes for mercuric ion reductase. This enzyme catalyzes the reduction of toxic, ionic mercury to volatile, elemental mercury having far lower toxicity. Early attempts to confer Hg<jats:sup>++</jats:sup> resistance to plants using the wildtype <jats:italic>merA</jats:italic> gene were unsuccessful. We hypothesized the highly GC-skewed codon usage was ineffective for efficient plant gene expression, and sequence modification would be necessary to confer <jats:italic>merA</jats:italic> gene activity and ionic mercury resistance in plants. A directed mutagenesis strategy is being used to develop modified <jats:italic>merA</jats:italic> gene constructs for transformation and analysis in plants species. Transgenic <jats:italic>Arabidopsis</jats:italic> and yellow-poplar plants having modified <jats:italic>merA</jats:italic> codon usage display Hg<jats:sup>++</jats:sup>-resistance. <jats:italic>Arabidopsis</jats:italic> plants with modified <jats:italic>merA</jats:italic> were observed to evolve ≈4 times the quantity of Hg<jats:sup>0</jats:sup> from aqueous Hg<jats:sup>++</jats:sup> in controlled experiments. In contrast, plants with unaltered <jats:italic>merA</jats:italic> coding sequences display unstable and inactivated gene expression. Our progress towards further <jats:italic>merA</jats:italic> modification and transgenic plant development will be reported. Additionally, the theoretical phytoremediative benefits and potential advantages of <jats:italic>merA</jats:italic>-expressing plant species will be discussed as part of our long-term goals.</jats:p>