Prominent cadmium(Cd)pollution and widespread phoxim(p H)use hinder the growth and medicinal value of Ligusticum chuanxiong Hort.(Chuanxiong).While bioremediation by rhizobacteria helps plants counter pollutants,the s...Prominent cadmium(Cd)pollution and widespread phoxim(p H)use hinder the growth and medicinal value of Ligusticum chuanxiong Hort.(Chuanxiong).While bioremediation by rhizobacteria helps plants counter pollutants,the specific roles of indigenous resistant consortia collected from polluted soils in immobilizing heavy metals,degrading pesticides,and enhancing plant stress tolerance remain insufficiently explored.Here,an indigenous pollutant-resistant consortium(RM)was developed from a highly Cd-polluted area(14.85 mg/kg Cd)as a bioremediation strategy to alleviate stress on Chuanxiong.The RM was specifically enriched with a Cd-p H co-resistant strain,Halomonas spp.TS2.Through16S r RNA sequencing,active microorganisms within RM was identified,including Bacillus,Acinetobacter,Enterococcus,Paraclostridium,and Staphylococcus.Pot experiments demonstrated that RM increased Chuanxiong biomass by 93.38%under Cd-contaminated and by 32.89%under Cd-p H co-contaminated.Furthermore,RM enhanced p H degradation,stabilized soil compounds,and reduced Cd bioavailability,thereby mitigating oxidative damage and altering the diversity and composition of Cd-p H-resistant organisms.These results indicate that utilizing indigenous microbial consortia as a bioremediation strategy can effectively improve soil health and enhance the sustainable cultivation of medicinal herbs in environments heavily contaminated.展开更多
Harnessing bacteria for superoxide production in bioremediation holds immense promise,yet its practical application is hindered by slow production rates and the relatively weak redox potential of superoxide.This study...Harnessing bacteria for superoxide production in bioremediation holds immense promise,yet its practical application is hindered by slow production rates and the relatively weak redox potential of superoxide.This study delves into a cost-effective approach to amplify superoxide production using an Arthrobacter strain,a prevalent soil bacterial genus.Our research reveals that introducing a carbon source along with specific iron-binding ligands,including deferoxamine(DFO),diethylenetriamine pentaacetate(DTPA),citrate,and oxalate,robustly augments microbial superoxide generation.Moreover,our findings suggest that these iron-binding ligands play a pivotal role in converting superoxide into hydroxyl radicals by modulating the electron transfer rate between Fe(Ⅲ)/Fe(Ⅱ)and superoxide.Remarkably,among the tested ligands,only DTPA emerges as a potent promoter of this conversion process when complexed with Fe(Ⅲ).We identify an optimal Fe(Ⅲ)to DTPA ratio of approximately 1:1 for enhancing hydroxyl radical production within the Arthrobacter culture.This research underscores the efficacy of simultaneously introducing carbon sources and DTPA in facilitating superoxide production and its subsequent conversion to hydroxyl radicals,significantly elevating bioremediation performance.Furthermore,our study reveals that DTPA augments superoxide production in cultures of diverse soils,with various soil microorganisms beyond Arthrobacter identified as contributors to superoxide generation.This emphasizes the universal applicability of DTPA across multiple bacterial genera.In conclusion,our study introduces a promising methodology for enhancing microbial superoxide production and its conversion into hydroxyl radicals.These findings hold substantial implications for the deployment of microbial reactive oxygen species in bioremediation,offering innovative solutions for addressing environmental contamination challenges.展开更多
Mariculture tailwater poses significant environmental challenges such as water pollution and eutrophication.Photosynthetic bacteria(PSB)have been widely used for pollutant treatment.The integrated aquaculture wastewat...Mariculture tailwater poses significant environmental challenges such as water pollution and eutrophication.Photosynthetic bacteria(PSB)have been widely used for pollutant treatment.The integrated aquaculture wastewater bioremediation system(IAWBS)consists of four key components:sedimentation,biofilm,shellfish,and macro-algae.However,there is still some room for improvement in the treatment efficiency of the IAWBS.In this study,PSB(Rhodopseudomonos,Rhodobacteria,Rhodococcus)were added to the system.High-throughput amplicon of 16S rRNA,PERMANOVA,NMDS and other statistical analyses were used to investigate the impacts of PSB.The results showed that significant removal efficiencies of CODMn,NH_(4)^(+)-N,NO_(3)^(-)-N,NO_(2)^(-)-N,PO_(4)^(3-)-P were 71.42%,91.37%,91.72%,87.20%,and 88.80%,respectively.The impact of PSB on bacterioplankton community(BC)was not affected by the time interval but affected by different units,Proteobacteria,Bacteriodia and Actinobacteria were the most abundant phyla in all the units.Alpha diversity underscored a significant decrease in bacterial community diversity due to the PSB.Notably,the PERMANOVA analysis highlighted a significant interaction between the time interval and treated unit,influencing the composition of the microbial community(R^(2)=0.152;P=0.001).This study provides a better understanding of the role of photosynthetic bacteria in an integrated bioremediation system that can effectively treat mariculture tailwater,which is of great significance for the sustainable development of aquaculture.展开更多
Petroleum extraction and its organic pollutants have numerous negative consequences on the composition and ecological function of grasslands,such as vegetation degradation,reduction in species diversity,and salinizati...Petroleum extraction and its organic pollutants have numerous negative consequences on the composition and ecological function of grasslands,such as vegetation degradation,reduction in species diversity,and salinization.Thus,finding a comprehensive method for polluted soil and restoring grasslands faces many challenges,and the mecha-nism to influence soil environments and microbial commu-nity composition remains unclear.In this study,container experiments explored the potential of sulfonic acid group(–SO3H groups)modified biochar combined with isolated bac-terium(named Y-1,Acinetobacter-spp.)on physicochemical properties and microbial communities of polluted soil.The results show that modified biochar and Y-1 combined addi-tion had the highest petroleum degradation rate(39.4%),and soil nutrients such as dissolved organic carbon(DOC),cat-ion exchange capacity(CEC),available nitrogen,invertase and urease activities in CK were decreased by 35.4,12.1,30,43.2 and 32.5%compared to treatments.The contents of available phosphorus in CM treatment were increased 2.4 times compared to CK.The-SO3H groups efficiently improve salinity by accumulating Ca2+and Mg2+and inhib-iting the aggregation of Na+.The correlation heatmap indi-cated that soil organic carbon,total nitrogen and CEC mark-edly interact with microbial communities.High-throughput sequencing indicated that the biomarkers enriched by the present integrated treatment are crucial for stimulating nitro-gen and phosphorus cycles.The results indicate that-SO3H groups modified biochar,and Y-1 has great potential to serve as a novel bioremediation technology to remediate soil from petroleum pollutants and alkalization and achieve better res-toration of degradation grasslands.展开更多
Nicosulfuron(NSR),a sulfonylurea herbicide,readily infiltrates water bodies,potentially compromising aquatic ecosystems and human health.In this study,bacteria consortium YM2 was isolated and cultivated from pesticide...Nicosulfuron(NSR),a sulfonylurea herbicide,readily infiltrates water bodies,potentially compromising aquatic ecosystems and human health.In this study,bacteria consortium YM2 was isolated and cultivated from pesticide plant active sludge for NSR wastewater bioremediation.Response surface methodology analysis demonstrated that under optimal cultivation conditions(9.41 g L^(-1)maltodextrin,21.37 g L^(-1)yeast extract,and 12.45 g L^(-1)NaCl),the YM2 bacteria consortium achieved 97.49%NSR degradation within 4 d.Optimal degradation parameters were established at 30℃,pH 6.0,1%inoculum,and 20 mg L^(-1)initial NSR concentration.The degradation system demonstrated resistance to heavy metal ions including Cd^(2+),Pb^(2+),Ni^(2+),and Zn^(2+),with degradation primarily occurring through bacterial extracellular enzymes(92.17%).During the degradation process,reactive oxygen species,oxidative stress,cell membrane permeability,cell surface hydrophobicity,and apoptosis rate exhibited initial increases followed by decreases.Additionally,bioflm formation-related genes luxS,waaE,spo0A,and wza showed temporal and concentration-dependent expression patterns.NSR concentrations in wastewater and soil were reduced to 1.92 and 2.72 mg L^(-1),respectively.In a simulated wastewater treatment unit with a 12-h hydraulic retention time,YM2 achieved 84.55%NSR degradation after 10 d.These fndings provide a theoretical foundation for microbial remediation of NSR contamination.展开更多
This research study explored the efficacy of leaf litter compost as a sustainable soil amendment with the objective of promoting soil health and mitigating the accumulation of potentially toxic elements. The investiga...This research study explored the efficacy of leaf litter compost as a sustainable soil amendment with the objective of promoting soil health and mitigating the accumulation of potentially toxic elements. The investigation encompassed the impact of various organic compost amendments, including leaf compost, cow dung manure, kitchen waste compost, municipal organic waste compost, and vermicompost. The study employed Inductively Coupled Plasma Mass Spectrometry (ICP-MS) to evaluate soil nutrient levels and concentrations of Potentially Toxic Elements (PTEs) such as arsenic, chromium, cadmium, mercury, lead, nickel, and lithium. The fertilization and bioremediation potential of these compost amendments are quantified using an indexing method. Results indicated a substantial increase in overall nutrient levels (carbon, nitrogen, phosphorus, potassium, and sulfur) in soils treated with leaf compost and other organic composts. Fertility indices (FI) are notably higher in compost-amended soils (ranging from 2.667 to 3.938) compared to those amended with chemical fertilizers (ranging from 2.250 to 2.813) across all soil samples. Furthermore, the mean concentrations of PTEs were significantly lower in soils treated with leaf compost and other organic compost amendments compared to those treated with chemical fertilizers amendments. The assessment through the indexing method revealed a high clean index (CI) for leaf compost amendment (ranging from 3.407 to 3.58), whereas the chemical fertilizer amendment exhibits a relatively lower CI (ranging from 2.78 to 3.20). Consequently, leaf compost and other organic composts exhibit the potential to enhance sustainable productivity, promoting soil health and environmental safety by improving nutrient levels and remediating potentially toxic elements in the soil.展开更多
[ Objective ] The aim was to study the bioremediation mechanism of soil pollution. [ Method ] The effects of applying biological organic fertilizers on the bioremediation of soil pollution in orchard were studid by ex...[ Objective ] The aim was to study the bioremediation mechanism of soil pollution. [ Method ] The effects of applying biological organic fertilizers on the bioremediation of soil pollution in orchard were studid by experiment in orchard field and soil simulative experiment. [ Result] The biological organic fertilizers improved the activities of enzymes like polyphenol oxidase, urease, phosphatase, etc. in root-zone soil, promoted the passivation of heavy metals like Cd^2＋ , Pb^2＋ , Cr^3＋ , As^8＋ , etc. in root-zone soil, increased the quantities of useful active bacterium like beneficial fungi, actinomycetes, bacterium, etc. and decreased the quantities of harmful biology （like Fusarium oxysporum, Moniliophthora roreri, Ruselliniu necutrix/Helicobasidium mompa, nematode, etc. [ Conclusion] The study results provide some references for the popularization and application of biological organic fertilizers on fruit trees.展开更多
In order to implement industrial production of selected functional bacteria for bioremediation of shrimp culture environment, the fermentation conditions of the three functional bacteria, which have high ability in de...In order to implement industrial production of selected functional bacteria for bioremediation of shrimp culture environment, the fermentation conditions of the three functional bacteria, which have high ability in degrading organic pollutants at the bottom of shrimp ponds, were studied. The results showed that the favorable fermentation medium （per L） was 25 g of peptone, 5 g of yeast extract, and 0.2 g of ferric phosphate, and the initial pH value of the medium was 8.0. The optimum fermentation time was 20 h. The optimum stirring way was stirring one hour after one hour. Iso-electric point sedimentation collecting method was the most efficient and economic method to collect the bacteria cells after fermentation, with the optimum sediment pH of 3.67, 4.02, and 3.40 for the strains Lt7222, Gy7018 and Lt7511,respectively. It was also indicated that the survival and reproducing ability of the bacterial cells were not affected by the sedimentation process.展开更多
Statistical work and analysis were made based on data of monitored wa- ter quality data in Hedi Reservoir during 2000-2010 and the results show that the content of nutritive salt was higher and water was moderate or l...Statistical work and analysis were made based on data of monitored wa- ter quality data in Hedi Reservoir during 2000-2010 and the results show that the content of nutritive salt was higher and water was moderate or light eutrophication. Based on status quo and practical survey research of the Reservoir, the causes for eutrophication deterioration were analyzed and countermeasures were proposed, providing scientific references for sustainable development of Hedi Reservoir.展开更多
Laboratory simulation studies and composting pilot study wereconducted to evaluate the capacity of three strains of fungi,indigenous fungus Fusarium sp. And Phanerochaete chrysosporium andCoriolus Versicolor, to remed...Laboratory simulation studies and composting pilot study wereconducted to evaluate the capacity of three strains of fungi,indigenous fungus Fusarium sp. And Phanerochaete chrysosporium andCoriolus Versicolor, to remediate petroleum-contaminated soils. Inlaboratory, the fungi were inoculated into a liquid Culture mediumand the petroleum-contaminated soil samples for incubation of 40 and50 days, respectively. In the 200-day pilot study, nutrient contentsand moisture were adjusted and maintained under aerobic Condition incomposting units using concrete container (118.5 cm×65.5 cm×12.5cm) designed specially For this study.展开更多
Along with the rapid development of oil industries internationally,petroleum prospecting and exploitation activities are growing intensively.Especially in China,with the fastest economic growth in the world and shorta...Along with the rapid development of oil industries internationally,petroleum prospecting and exploitation activities are growing intensively.Especially in China,with the fastest economic growth in the world and shortage of petroleum resources,we are leading the practices of petroleum deep exploitation.Obviously,the risk of damage to the natural environment from these activities is high.Oil contamination in soils and groundwater is becoming a big issue along with pesticide pollution,which makes organic pollution prevention and control （OPPC） much more complex.In this paper,based on recent research on oil-contaminated soil at home and abroad,we make comments on the remediation technologies for polluted soil,emphasizing bioremediation techniques and degradation mechanisms in order to push forward research into bound organic pollution prevention and control （OPPC）,especially in China.展开更多
A bacterial strain (AD26) capable of utilizing atrazine as a sole nitrogen source for growth was isolated from an industrial wastewater sample by enrichment culture. The 16S rRNA gene sequencing identified AD26 as an ...A bacterial strain (AD26) capable of utilizing atrazine as a sole nitrogen source for growth was isolated from an industrial wastewater sample by enrichment culture. The 16S rRNA gene sequencing identified AD26 as an Arthrobacter sp. PCR assays indicated that AD26 contained atrazine-degrading genes trzN and atzBC. The trzN gene of AD26 only differs from the trzN of Arthrobacter aurescens TC1 by one base (A→T at 907) and one amino acid (Met→Leu at 303). The specific activity of trzN of AD26 in crude cell ext...展开更多
Graded modified Fenton’s （MF） oxidation is a strategy in which H 2 O 2 is added intermittently to prevent a sharp temperature increase and undesired soil sterilization at soil circumneutral pH versus adding the sam...Graded modified Fenton’s （MF） oxidation is a strategy in which H 2 O 2 is added intermittently to prevent a sharp temperature increase and undesired soil sterilization at soil circumneutral pH versus adding the same amount of H 2 O 2 continuously.The primary objective of the present study was to investigate whether a mild MF pre-oxidation such as a stepwise addition of H 2 O 2 can prevent sterilization and achieve a maximum degradation of tank oil in soil.Optimization experiments of graded MF oxidation were conducted using citric acid,oxalic acid and SOLV-X as iron chelators under different frequencies of H 2 O 2 addition.The results indicated that the activity order of iron chelates decreased as：citric acid （51%） SOLV-X （44%） oxalic acid （9%）,and citric acid was found to be an optimized iron chelating agent of graded MF oxidation.Three-time addition of H 2 O 2 was found to be favorable and economical due to decreasing total petroleum hydrocarbon removal from three time addition （51%） to five time addition （59%）.Biological experiments were conducted after graded MF oxidation of tank oil completed under optimum conditions mentioned above.After graded oxidation,substantially higher increase （31%） in microbial activity was observed with excessive H 2 O 2 （1470 mmol/L,the mol ratio of H 2 O 2：Fe 2＋ was 210：1） than that of non-oxidized soil.Removal efficiency of tank oil was up to 93% after four weeks.Especially,the oil fraction （C 10 –C 40 ） became more biodagradable after graded MF oxidation than its absence.Therefore,graded MF oxidation is a mild pretreatment to achieve an effective bioremediation of oil contaminated soil.展开更多
The use of surfactants to enhance plant-microbe associated dissipation in soils contaminated with polycyclic aromatic hydrocarbons （PAHs） is a promising bioremediation technology. This comparative study was conducte...The use of surfactants to enhance plant-microbe associated dissipation in soils contaminated with polycyclic aromatic hydrocarbons （PAHs） is a promising bioremediation technology. This comparative study was conducted on the effects of plant-microbe treatment on the removal of phenanthrene and pyrene from contaminated soil, in the presence of low concentration single anionic, nonionic and anionic-nonionic mixed surfactants. Sodium dodecyl benzene sulfonate （SDBS） and Tween 80 were chosen as representative anionic and nonionic surfactants, respectively. We found that mixed surfactants with concentrations less than 150 mg/kg were more effective in promoting plant-microbe associated bioremediation than the same amount of single surfactants. Only about （m/m） of mixed surfactants was needed to remove the same amount of phenanthrene and pyrene from either the planted or unplanted soils, when compared to Tween 80. Mixed surfactants （〈 150 mg/kg） better enhanced the degradation efficiency of phenanthrene and pyrene via microbe or plant-microbe routes in the soils. In the concentration range of 60-150 mg/kg, both ryegrass roots and shoots could accumulate 2-3 times the phenanthrene and pyrene with mixed surfactants than with Tween 80. These results may be explained by the lower sorption loss and reduced inteffacial tension of mixed surfactants relative to Tween 80, which enhanced the bioavailability of PAHs in soil and the microbial degradation efficiency. The higher remediation efficiency of low dosage SDBS-Tween 80 mixed surfactants thus advanced the technology of surfactant-enhanced plant-microbe associated bioremediation.展开更多
The present study was aimed to assess the ability of Bacillus sp.JDM-2-1 and Staphylococcus capitis to reduce hexavalent chromium into its trivalent form.Bacillus sp.JDM-2-1 could tolerate Cr（Ⅵ）（4800 μg/mL） and ...The present study was aimed to assess the ability of Bacillus sp.JDM-2-1 and Staphylococcus capitis to reduce hexavalent chromium into its trivalent form.Bacillus sp.JDM-2-1 could tolerate Cr（Ⅵ）（4800 μg/mL） and S.capitis could tolerate Cr（Ⅵ）（2800 μg/mL）.Both organisms were able to resist Cd^2＋（50 μg/mL）,Cu^2＋（200 μg/mL）,Pb^2＋（800 μg/mL）,Hg^2＋（50 μg/mL） and Ni2＋（4000 μg/mL）.S.capitis resisted Zn^2＋ at 700 μg/mL while Bacillus sp.JDM-2-1 only showed resistance up to 50 μg/mL.Bacillus sp.JDM-2-1 and S.capitis showed optimum growth at pH 6 and 7,respectively,while both bacteria showed optimum growth at 37°C.Bacillus sp.JDM-2-1 and S.capitis could reduce 85% and 81% of hexavalent chromium from the medium after 96 h and were also capable of reducing hexavalent chromium 86% and 89%,respectively,from the industrial effuents after 144 h.Cell free extracts of Bacillus sp.JDM-2-1 and S.capitis showed reduction of 83% and 70% at concentration of 10 μg Cr（Ⅵ）/mL,respectively.The presence of an induced protein having molecular weight around 25 kDa in the presence of chromium points out a possible role of this protein in chromium reduction.The bacterial isolates can be exploited for the bioremediation of hexavalent chromium containing wastes,since they seem to have a potential to reduce the toxic hexavalent form to its nontoxic trivalent form.展开更多
Oil spills have become a serious problem in cold environments with the ever-increasing resource exploitation, transportation, storage, and accidental leakage of oil. Several techniques, including physical, chemical, a...Oil spills have become a serious problem in cold environments with the ever-increasing resource exploitation, transportation, storage, and accidental leakage of oil. Several techniques, including physical, chemical, and biological methods, are used to recover spilled oil from the environment. Bioremediation is a promising option for remediation since it is effective and economic in removing oil with less undue environmental damages. However, it is a relatively slow process in cold regions and the degree of success depends on a number of factors, including the properties and fate of oil spilled in cold environments, and the major microbial and environmental limitations of bioremediation. The microbial factors include bioavailability of hydrocarbons, mass transfer through the cell membrane, and metabolic limitations. As for the environmental limitations in the cold regions, the emphasis is on soil temperatures, freeze-thaw processes, oxygen and nutrients availability, toxicity, and electron acceptors. There have been several cases of success in the polar regions, particularly in the Arctic and sub-Arctic regions. However, the challenges and constraints for bioremediation in cold environments remain large.展开更多
Since the early 1980’s there have been several different strategies designed and applied to the remediation of subsurface environment including physical, chemical and biological approaches.They have had varying degre...Since the early 1980’s there have been several different strategies designed and applied to the remediation of subsurface environment including physical, chemical and biological approaches.They have had varying degrees of success in remediating contaminants from subsurface soils and groundwater.The objective of this review is to examine the range of technologies for the remediation of contaminants, particularly petroleum hydrocarbons, in subsurfaces with a specific focus on bioremediation and electrokinetic remediation.Further, this review examines the efficiency of remediation carried out by combining bioremediation and electrokinetic remediation.Surfactants, which are slowly becoming the selected chemicals for mobilizing contaminants, are also considered in this review.The current knowledge gaps of these technologies and techniques identified which could lead to development of more efficient ways of utilizing these technologies or development of a completely new technology.展开更多
The bioremediation of a long-term contaminated soil through biostimulation and surfactant addition was evaluated. The concentrations of 1,1,1-trichloro-2,2-bis（4-chlorophenyl）ethane（DDT） and its metabolites 1,1-di...The bioremediation of a long-term contaminated soil through biostimulation and surfactant addition was evaluated. The concentrations of 1,1,1-trichloro-2,2-bis（4-chlorophenyl）ethane（DDT） and its metabolites 1,1-dichloro-2,2-bis（4-chlorophenyl） ethane（DDD） and1,1-dichloro-2,2-bis（4-chlorophenyl） ethylene（DDE） were monitored during an 8-week remediation process. Physicochemical characterization of the treated soil was performed before and after the bioremediation process. The isolation and identification of predominant microorganisms during the remediation process were also carried out. The efficiency of detoxification was evaluated after each bioremediation protocol. Humidity and p H and the heterotrophic microorganism count were monitored weekly. The DDT concentration was reduced by 79% after 8 weeks via biostimulation with surfactant addition（B ＋ S） and 94.3%via biostimulation alone（B）. Likewise, the concentrations of the metabolites DDE and DDD were reduced to levels below the quantification limits. The microorganisms isolated during bioremediation were identified as Bacillus thuringiensis, Flavobacterium sp., Cuprivadius sp.,Variovorax soli, Phenylobacterium sp. and Lysobacter sp., among others. Analysis with scanning electron microscopy（SEM） allowed visualization of the colonization patterns of soil particles. The toxicity of the soil before and after bioremediation was evaluated using Vibrio fischeri as a bioluminescent sensor. A decrease in the toxic potential of the soil was verified by the increase of the concentration/effect relationship EC50 to 26.9% and 27.2% for B ＋ S and B, respectively, compared to 0.4% obtained for the soil before treatment and 2.5%by natural attenuation after 8 weeks of treatment.展开更多
This study examines the possibility of using live spirulina to biologically remove aqueous lead of low concentration (below 50 mg/L) from wastewater. The spirulina cells were first immersed for seven days in five wast...This study examines the possibility of using live spirulina to biologically remove aqueous lead of low concentration (below 50 mg/L) from wastewater. The spirulina cells were first immersed for seven days in five wastewater samples containing lead of different concentrations, and the growth rate was determined by light at wavelength of 560 nm. The 72 h-EC50 (72 h medium effective concentration) was estimated to be 11.46 mg/L (lead). Afterwards, the lead adsorption by live spirulina cells was conducted. It was observed that at the initial stage (0–12 min) the adsorption rate was so rapid that 74% of the metal was bio- logically adsorbed. The maximum biosorption capacity of live spirulina was estimated to be 0.62 mg lead per 105 alga cells.展开更多
Leakage of oil and its derivatives into the soil can change the engineering behavior of soil as well as cause environmental disasters.Also,recovering the contaminated sites into their natural condition and making cont...Leakage of oil and its derivatives into the soil can change the engineering behavior of soil as well as cause environmental disasters.Also,recovering the contaminated sites into their natural condition and making contaminated materials as both environmentally and geotechnically suitable construction materials need the employment of remediation techniques.Bioremediation,as an efficient,low cost and environmentalfriendly approach,was used in the case of highly plastic clayey soils.To better understand the change in geotechnical properties of highly plastic fine-grained soil due to crude oil contamination and bioremediation,Atterberg limits,compaction,unconfined compression,direct shear,and consolidation tests were conducted on natural,contaminated,and bioremediated soil samples to investigate the effects of contamination and remediation on fine-grained soil properties.Oil contamination reduced maximum dry density(MDD),optimum moisture content(OMC),unconfined compressive strength(UCS),shear strength,swelling pressure,and coefficient of consolidation of soil.In addition,contamination increased the compression and swelling indices and compressibility of soil.Bioremediation reduced soil contamination by about 50%.Moreover,in comparison with contaminated soil,bioremediation reduced the MDD,UCS,swelling index,free swelling and swelling pressure of soil,and also increased OMC,shear strength,cohesion,internal friction angle,failure strain,porosity,compression index,and settlement.Microstructural analyses showed that oil contamination does not alter the soil structure in terms of chemical compounds,elements,and constituent minerals.While it decreased the specific surface area of the soil,and the bioremediation significantly increased the mentioned parameters.Bioremediation resulted in the formation of quasi-fibrous textures and porous and agglomerated structures.As a result,oil contamination affected the mechanical properties of soil negatively,but bioremediation improved these properties.展开更多
基金supported by the National Natural Science Foundation of China(Nos.51978576,42207021 and 52370177)Sichuan Province Science and Technology Support Program(Nos.2023ZHCG0058,2025ZNSFSC0194 and 2024NSFSC0131)+1 种基金the Fundamental Research Funds for the Central Universities(No.2682024ZTPY012)the Science and Technology Project of Sichuan Tobacco Company of China National Tobacco Corporation(Nos.SCYC202109 and SCYC202409)。
文摘Prominent cadmium(Cd)pollution and widespread phoxim(p H)use hinder the growth and medicinal value of Ligusticum chuanxiong Hort.(Chuanxiong).While bioremediation by rhizobacteria helps plants counter pollutants,the specific roles of indigenous resistant consortia collected from polluted soils in immobilizing heavy metals,degrading pesticides,and enhancing plant stress tolerance remain insufficiently explored.Here,an indigenous pollutant-resistant consortium(RM)was developed from a highly Cd-polluted area(14.85 mg/kg Cd)as a bioremediation strategy to alleviate stress on Chuanxiong.The RM was specifically enriched with a Cd-p H co-resistant strain,Halomonas spp.TS2.Through16S r RNA sequencing,active microorganisms within RM was identified,including Bacillus,Acinetobacter,Enterococcus,Paraclostridium,and Staphylococcus.Pot experiments demonstrated that RM increased Chuanxiong biomass by 93.38%under Cd-contaminated and by 32.89%under Cd-p H co-contaminated.Furthermore,RM enhanced p H degradation,stabilized soil compounds,and reduced Cd bioavailability,thereby mitigating oxidative damage and altering the diversity and composition of Cd-p H-resistant organisms.These results indicate that utilizing indigenous microbial consortia as a bioremediation strategy can effectively improve soil health and enhance the sustainable cultivation of medicinal herbs in environments heavily contaminated.
基金supported by the National Natural Science Foundation of China(Nos.52170156,52250056,and 52293443)the Shenzhen Science and Technology Program(No.KQTD20190929172630447).
文摘Harnessing bacteria for superoxide production in bioremediation holds immense promise,yet its practical application is hindered by slow production rates and the relatively weak redox potential of superoxide.This study delves into a cost-effective approach to amplify superoxide production using an Arthrobacter strain,a prevalent soil bacterial genus.Our research reveals that introducing a carbon source along with specific iron-binding ligands,including deferoxamine(DFO),diethylenetriamine pentaacetate(DTPA),citrate,and oxalate,robustly augments microbial superoxide generation.Moreover,our findings suggest that these iron-binding ligands play a pivotal role in converting superoxide into hydroxyl radicals by modulating the electron transfer rate between Fe(Ⅲ)/Fe(Ⅱ)and superoxide.Remarkably,among the tested ligands,only DTPA emerges as a potent promoter of this conversion process when complexed with Fe(Ⅲ).We identify an optimal Fe(Ⅲ)to DTPA ratio of approximately 1:1 for enhancing hydroxyl radical production within the Arthrobacter culture.This research underscores the efficacy of simultaneously introducing carbon sources and DTPA in facilitating superoxide production and its subsequent conversion to hydroxyl radicals,significantly elevating bioremediation performance.Furthermore,our study reveals that DTPA augments superoxide production in cultures of diverse soils,with various soil microorganisms beyond Arthrobacter identified as contributors to superoxide generation.This emphasizes the universal applicability of DTPA across multiple bacterial genera.In conclusion,our study introduces a promising methodology for enhancing microbial superoxide production and its conversion into hydroxyl radicals.These findings hold substantial implications for the deployment of microbial reactive oxygen species in bioremediation,offering innovative solutions for addressing environmental contamination challenges.
基金financially supported by the National Key R&D Program of China(No.2020YFD0900201)the Ningbo Public Welfare Technology Application Research Project(No.2022S164)the K.C.Wong Magna Fund in Ningbo University。
文摘Mariculture tailwater poses significant environmental challenges such as water pollution and eutrophication.Photosynthetic bacteria(PSB)have been widely used for pollutant treatment.The integrated aquaculture wastewater bioremediation system(IAWBS)consists of four key components:sedimentation,biofilm,shellfish,and macro-algae.However,there is still some room for improvement in the treatment efficiency of the IAWBS.In this study,PSB(Rhodopseudomonos,Rhodobacteria,Rhodococcus)were added to the system.High-throughput amplicon of 16S rRNA,PERMANOVA,NMDS and other statistical analyses were used to investigate the impacts of PSB.The results showed that significant removal efficiencies of CODMn,NH_(4)^(+)-N,NO_(3)^(-)-N,NO_(2)^(-)-N,PO_(4)^(3-)-P were 71.42%,91.37%,91.72%,87.20%,and 88.80%,respectively.The impact of PSB on bacterioplankton community(BC)was not affected by the time interval but affected by different units,Proteobacteria,Bacteriodia and Actinobacteria were the most abundant phyla in all the units.Alpha diversity underscored a significant decrease in bacterial community diversity due to the PSB.Notably,the PERMANOVA analysis highlighted a significant interaction between the time interval and treated unit,influencing the composition of the microbial community(R^(2)=0.152;P=0.001).This study provides a better understanding of the role of photosynthetic bacteria in an integrated bioremediation system that can effectively treat mariculture tailwater,which is of great significance for the sustainable development of aquaculture.
基金Natural Science Foundation of Heilongjiang Province(LH2023E009)the Fundamental Research Funds for the Central Universities(2572021BA01)the Ecological and Environmental Protection project of Heilongjiang Province(HST2022ST004).
文摘Petroleum extraction and its organic pollutants have numerous negative consequences on the composition and ecological function of grasslands,such as vegetation degradation,reduction in species diversity,and salinization.Thus,finding a comprehensive method for polluted soil and restoring grasslands faces many challenges,and the mecha-nism to influence soil environments and microbial commu-nity composition remains unclear.In this study,container experiments explored the potential of sulfonic acid group(–SO3H groups)modified biochar combined with isolated bac-terium(named Y-1,Acinetobacter-spp.)on physicochemical properties and microbial communities of polluted soil.The results show that modified biochar and Y-1 combined addi-tion had the highest petroleum degradation rate(39.4%),and soil nutrients such as dissolved organic carbon(DOC),cat-ion exchange capacity(CEC),available nitrogen,invertase and urease activities in CK were decreased by 35.4,12.1,30,43.2 and 32.5%compared to treatments.The contents of available phosphorus in CM treatment were increased 2.4 times compared to CK.The-SO3H groups efficiently improve salinity by accumulating Ca2+and Mg2+and inhib-iting the aggregation of Na+.The correlation heatmap indi-cated that soil organic carbon,total nitrogen and CEC mark-edly interact with microbial communities.High-throughput sequencing indicated that the biomarkers enriched by the present integrated treatment are crucial for stimulating nitro-gen and phosphorus cycles.The results indicate that-SO3H groups modified biochar,and Y-1 has great potential to serve as a novel bioremediation technology to remediate soil from petroleum pollutants and alkalization and achieve better res-toration of degradation grasslands.
基金financially supported by the Jilin Province Development and Reform Commission(Innovation Capacity Building)Project,China(20231036-3)the Key R&D Project of the Science and Technology Development Plan of Jilin,China(20230203014SF)。
文摘Nicosulfuron(NSR),a sulfonylurea herbicide,readily infiltrates water bodies,potentially compromising aquatic ecosystems and human health.In this study,bacteria consortium YM2 was isolated and cultivated from pesticide plant active sludge for NSR wastewater bioremediation.Response surface methodology analysis demonstrated that under optimal cultivation conditions(9.41 g L^(-1)maltodextrin,21.37 g L^(-1)yeast extract,and 12.45 g L^(-1)NaCl),the YM2 bacteria consortium achieved 97.49%NSR degradation within 4 d.Optimal degradation parameters were established at 30℃,pH 6.0,1%inoculum,and 20 mg L^(-1)initial NSR concentration.The degradation system demonstrated resistance to heavy metal ions including Cd^(2+),Pb^(2+),Ni^(2+),and Zn^(2+),with degradation primarily occurring through bacterial extracellular enzymes(92.17%).During the degradation process,reactive oxygen species,oxidative stress,cell membrane permeability,cell surface hydrophobicity,and apoptosis rate exhibited initial increases followed by decreases.Additionally,bioflm formation-related genes luxS,waaE,spo0A,and wza showed temporal and concentration-dependent expression patterns.NSR concentrations in wastewater and soil were reduced to 1.92 and 2.72 mg L^(-1),respectively.In a simulated wastewater treatment unit with a 12-h hydraulic retention time,YM2 achieved 84.55%NSR degradation after 10 d.These fndings provide a theoretical foundation for microbial remediation of NSR contamination.
文摘This research study explored the efficacy of leaf litter compost as a sustainable soil amendment with the objective of promoting soil health and mitigating the accumulation of potentially toxic elements. The investigation encompassed the impact of various organic compost amendments, including leaf compost, cow dung manure, kitchen waste compost, municipal organic waste compost, and vermicompost. The study employed Inductively Coupled Plasma Mass Spectrometry (ICP-MS) to evaluate soil nutrient levels and concentrations of Potentially Toxic Elements (PTEs) such as arsenic, chromium, cadmium, mercury, lead, nickel, and lithium. The fertilization and bioremediation potential of these compost amendments are quantified using an indexing method. Results indicated a substantial increase in overall nutrient levels (carbon, nitrogen, phosphorus, potassium, and sulfur) in soils treated with leaf compost and other organic composts. Fertility indices (FI) are notably higher in compost-amended soils (ranging from 2.667 to 3.938) compared to those amended with chemical fertilizers (ranging from 2.250 to 2.813) across all soil samples. Furthermore, the mean concentrations of PTEs were significantly lower in soils treated with leaf compost and other organic compost amendments compared to those treated with chemical fertilizers amendments. The assessment through the indexing method revealed a high clean index (CI) for leaf compost amendment (ranging from 3.407 to 3.58), whereas the chemical fertilizer amendment exhibits a relatively lower CI (ranging from 2.78 to 3.20). Consequently, leaf compost and other organic composts exhibit the potential to enhance sustainable productivity, promoting soil health and environmental safety by improving nutrient levels and remediating potentially toxic elements in the soil.
基金Supported by Natural Science Foundation of Liaoning Province(20082131)~~
文摘[ Objective ] The aim was to study the bioremediation mechanism of soil pollution. [ Method ] The effects of applying biological organic fertilizers on the bioremediation of soil pollution in orchard were studid by experiment in orchard field and soil simulative experiment. [ Result] The biological organic fertilizers improved the activities of enzymes like polyphenol oxidase, urease, phosphatase, etc. in root-zone soil, promoted the passivation of heavy metals like Cd^2＋ , Pb^2＋ , Cr^3＋ , As^8＋ , etc. in root-zone soil, increased the quantities of useful active bacterium like beneficial fungi, actinomycetes, bacterium, etc. and decreased the quantities of harmful biology （like Fusarium oxysporum, Moniliophthora roreri, Ruselliniu necutrix/Helicobasidium mompa, nematode, etc. [ Conclusion] The study results provide some references for the popularization and application of biological organic fertilizers on fruit trees.
文摘In order to implement industrial production of selected functional bacteria for bioremediation of shrimp culture environment, the fermentation conditions of the three functional bacteria, which have high ability in degrading organic pollutants at the bottom of shrimp ponds, were studied. The results showed that the favorable fermentation medium （per L） was 25 g of peptone, 5 g of yeast extract, and 0.2 g of ferric phosphate, and the initial pH value of the medium was 8.0. The optimum fermentation time was 20 h. The optimum stirring way was stirring one hour after one hour. Iso-electric point sedimentation collecting method was the most efficient and economic method to collect the bacteria cells after fermentation, with the optimum sediment pH of 3.67, 4.02, and 3.40 for the strains Lt7222, Gy7018 and Lt7511,respectively. It was also indicated that the survival and reproducing ability of the bacterial cells were not affected by the sedimentation process.
基金Supported by Guangdong Natural Science Foundation(8152500002000005)Guangdong Science and Technology Project(2011B030800017)Zhanjiang Normal University Talents Introduction and Undergraduates Innovation Program~~
文摘Statistical work and analysis were made based on data of monitored wa- ter quality data in Hedi Reservoir during 2000-2010 and the results show that the content of nutritive salt was higher and water was moderate or light eutrophication. Based on status quo and practical survey research of the Reservoir, the causes for eutrophication deterioration were analyzed and countermeasures were proposed, providing scientific references for sustainable development of Hedi Reservoir.
基金National Natural Science Foundation of China(No.49831070) the ChineseAcademy of Sciences(No.KZ951-B1-207-01-03).
文摘Laboratory simulation studies and composting pilot study wereconducted to evaluate the capacity of three strains of fungi,indigenous fungus Fusarium sp. And Phanerochaete chrysosporium andCoriolus Versicolor, to remediate petroleum-contaminated soils. Inlaboratory, the fungi were inoculated into a liquid Culture mediumand the petroleum-contaminated soil samples for incubation of 40 and50 days, respectively. In the 200-day pilot study, nutrient contentsand moisture were adjusted and maintained under aerobic Condition incomposting units using concrete container (118.5 cm×65.5 cm×12.5cm) designed specially For this study.
基金supports from the New Century Excellent Talents in University of Ministry of Education (NCET-09-0765)the China Scholarship of Council (2009644509)the Natural Scientific Funds of China (40973064)
文摘Along with the rapid development of oil industries internationally,petroleum prospecting and exploitation activities are growing intensively.Especially in China,with the fastest economic growth in the world and shortage of petroleum resources,we are leading the practices of petroleum deep exploitation.Obviously,the risk of damage to the natural environment from these activities is high.Oil contamination in soils and groundwater is becoming a big issue along with pesticide pollution,which makes organic pollution prevention and control （OPPC） much more complex.In this paper,based on recent research on oil-contaminated soil at home and abroad,we make comments on the remediation technologies for polluted soil,emphasizing bioremediation techniques and degradation mechanisms in order to push forward research into bound organic pollution prevention and control （OPPC）,especially in China.
文摘A bacterial strain (AD26) capable of utilizing atrazine as a sole nitrogen source for growth was isolated from an industrial wastewater sample by enrichment culture. The 16S rRNA gene sequencing identified AD26 as an Arthrobacter sp. PCR assays indicated that AD26 contained atrazine-degrading genes trzN and atzBC. The trzN gene of AD26 only differs from the trzN of Arthrobacter aurescens TC1 by one base (A→T at 907) and one amino acid (Met→Leu at 303). The specific activity of trzN of AD26 in crude cell ext...
基金supported by the Program of In-ternational S&T Cooperation(No.2010 DFA 94550,2010KW-24-1)the National Natural Science Founda-tion of China(No.50830303)+1 种基金the Major Science and Technology Program for Water Pollution Control and Treatment(No.2009ZX07317-007-001)the Program for Changjiang Scholars and Innovative Research Team in University(No.IRT0853)
文摘Graded modified Fenton’s （MF） oxidation is a strategy in which H 2 O 2 is added intermittently to prevent a sharp temperature increase and undesired soil sterilization at soil circumneutral pH versus adding the same amount of H 2 O 2 continuously.The primary objective of the present study was to investigate whether a mild MF pre-oxidation such as a stepwise addition of H 2 O 2 can prevent sterilization and achieve a maximum degradation of tank oil in soil.Optimization experiments of graded MF oxidation were conducted using citric acid,oxalic acid and SOLV-X as iron chelators under different frequencies of H 2 O 2 addition.The results indicated that the activity order of iron chelates decreased as：citric acid （51%） SOLV-X （44%） oxalic acid （9%）,and citric acid was found to be an optimized iron chelating agent of graded MF oxidation.Three-time addition of H 2 O 2 was found to be favorable and economical due to decreasing total petroleum hydrocarbon removal from three time addition （51%） to five time addition （59%）.Biological experiments were conducted after graded MF oxidation of tank oil completed under optimum conditions mentioned above.After graded oxidation,substantially higher increase （31%） in microbial activity was observed with excessive H 2 O 2 （1470 mmol/L,the mol ratio of H 2 O 2：Fe 2＋ was 210：1） than that of non-oxidized soil.Removal efficiency of tank oil was up to 93% after four weeks.Especially,the oil fraction （C 10 –C 40 ） became more biodagradable after graded MF oxidation than its absence.Therefore,graded MF oxidation is a mild pretreatment to achieve an effective bioremediation of oil contaminated soil.
基金supported by the National Natural Science Foundation of China(No.21137003)the National KeyBasic Research Program of China(No.2014CB441106)
文摘The use of surfactants to enhance plant-microbe associated dissipation in soils contaminated with polycyclic aromatic hydrocarbons （PAHs） is a promising bioremediation technology. This comparative study was conducted on the effects of plant-microbe treatment on the removal of phenanthrene and pyrene from contaminated soil, in the presence of low concentration single anionic, nonionic and anionic-nonionic mixed surfactants. Sodium dodecyl benzene sulfonate （SDBS） and Tween 80 were chosen as representative anionic and nonionic surfactants, respectively. We found that mixed surfactants with concentrations less than 150 mg/kg were more effective in promoting plant-microbe associated bioremediation than the same amount of single surfactants. Only about （m/m） of mixed surfactants was needed to remove the same amount of phenanthrene and pyrene from either the planted or unplanted soils, when compared to Tween 80. Mixed surfactants （〈 150 mg/kg） better enhanced the degradation efficiency of phenanthrene and pyrene via microbe or plant-microbe routes in the soils. In the concentration range of 60-150 mg/kg, both ryegrass roots and shoots could accumulate 2-3 times the phenanthrene and pyrene with mixed surfactants than with Tween 80. These results may be explained by the lower sorption loss and reduced inteffacial tension of mixed surfactants relative to Tween 80, which enhanced the bioavailability of PAHs in soil and the microbial degradation efficiency. The higher remediation efficiency of low dosage SDBS-Tween 80 mixed surfactants thus advanced the technology of surfactant-enhanced plant-microbe associated bioremediation.
文摘The present study was aimed to assess the ability of Bacillus sp.JDM-2-1 and Staphylococcus capitis to reduce hexavalent chromium into its trivalent form.Bacillus sp.JDM-2-1 could tolerate Cr（Ⅵ）（4800 μg/mL） and S.capitis could tolerate Cr（Ⅵ）（2800 μg/mL）.Both organisms were able to resist Cd^2＋（50 μg/mL）,Cu^2＋（200 μg/mL）,Pb^2＋（800 μg/mL）,Hg^2＋（50 μg/mL） and Ni2＋（4000 μg/mL）.S.capitis resisted Zn^2＋ at 700 μg/mL while Bacillus sp.JDM-2-1 only showed resistance up to 50 μg/mL.Bacillus sp.JDM-2-1 and S.capitis showed optimum growth at pH 6 and 7,respectively,while both bacteria showed optimum growth at 37°C.Bacillus sp.JDM-2-1 and S.capitis could reduce 85% and 81% of hexavalent chromium from the medium after 96 h and were also capable of reducing hexavalent chromium 86% and 89%,respectively,from the industrial effuents after 144 h.Cell free extracts of Bacillus sp.JDM-2-1 and S.capitis showed reduction of 83% and 70% at concentration of 10 μg Cr（Ⅵ）/mL,respectively.The presence of an induced protein having molecular weight around 25 kDa in the presence of chromium points out a possible role of this protein in chromium reduction.The bacterial isolates can be exploited for the bioremediation of hexavalent chromium containing wastes,since they seem to have a potential to reduce the toxic hexavalent form to its nontoxic trivalent form.
基金Project supported by the 100 Talents Program of the Chinese Academy of Sciences (No.2004407).
文摘Oil spills have become a serious problem in cold environments with the ever-increasing resource exploitation, transportation, storage, and accidental leakage of oil. Several techniques, including physical, chemical, and biological methods, are used to recover spilled oil from the environment. Bioremediation is a promising option for remediation since it is effective and economic in removing oil with less undue environmental damages. However, it is a relatively slow process in cold regions and the degree of success depends on a number of factors, including the properties and fate of oil spilled in cold environments, and the major microbial and environmental limitations of bioremediation. The microbial factors include bioavailability of hydrocarbons, mass transfer through the cell membrane, and metabolic limitations. As for the environmental limitations in the cold regions, the emphasis is on soil temperatures, freeze-thaw processes, oxygen and nutrients availability, toxicity, and electron acceptors. There have been several cases of success in the polar regions, particularly in the Arctic and sub-Arctic regions. However, the challenges and constraints for bioremediation in cold environments remain large.
基金funded through Cooperative Research Center for Contamination Assessment and Remediation of the Environment (CRC CARE)the University of Newcastle.
文摘Since the early 1980’s there have been several different strategies designed and applied to the remediation of subsurface environment including physical, chemical and biological approaches.They have had varying degrees of success in remediating contaminants from subsurface soils and groundwater.The objective of this review is to examine the range of technologies for the remediation of contaminants, particularly petroleum hydrocarbons, in subsurfaces with a specific focus on bioremediation and electrokinetic remediation.Further, this review examines the efficiency of remediation carried out by combining bioremediation and electrokinetic remediation.Surfactants, which are slowly becoming the selected chemicals for mobilizing contaminants, are also considered in this review.The current knowledge gaps of these technologies and techniques identified which could lead to development of more efficient ways of utilizing these technologies or development of a completely new technology.
基金the GDCON group and the 2013–2014 sustainability grant of the Pro-Vice Chancellor for Research of the University of Antioquia for funding the project
文摘The bioremediation of a long-term contaminated soil through biostimulation and surfactant addition was evaluated. The concentrations of 1,1,1-trichloro-2,2-bis（4-chlorophenyl）ethane（DDT） and its metabolites 1,1-dichloro-2,2-bis（4-chlorophenyl） ethane（DDD） and1,1-dichloro-2,2-bis（4-chlorophenyl） ethylene（DDE） were monitored during an 8-week remediation process. Physicochemical characterization of the treated soil was performed before and after the bioremediation process. The isolation and identification of predominant microorganisms during the remediation process were also carried out. The efficiency of detoxification was evaluated after each bioremediation protocol. Humidity and p H and the heterotrophic microorganism count were monitored weekly. The DDT concentration was reduced by 79% after 8 weeks via biostimulation with surfactant addition（B ＋ S） and 94.3%via biostimulation alone（B）. Likewise, the concentrations of the metabolites DDE and DDD were reduced to levels below the quantification limits. The microorganisms isolated during bioremediation were identified as Bacillus thuringiensis, Flavobacterium sp., Cuprivadius sp.,Variovorax soli, Phenylobacterium sp. and Lysobacter sp., among others. Analysis with scanning electron microscopy（SEM） allowed visualization of the colonization patterns of soil particles. The toxicity of the soil before and after bioremediation was evaluated using Vibrio fischeri as a bioluminescent sensor. A decrease in the toxic potential of the soil was verified by the increase of the concentration/effect relationship EC50 to 26.9% and 27.2% for B ＋ S and B, respectively, compared to 0.4% obtained for the soil before treatment and 2.5%by natural attenuation after 8 weeks of treatment.
文摘This study examines the possibility of using live spirulina to biologically remove aqueous lead of low concentration (below 50 mg/L) from wastewater. The spirulina cells were first immersed for seven days in five wastewater samples containing lead of different concentrations, and the growth rate was determined by light at wavelength of 560 nm. The 72 h-EC50 (72 h medium effective concentration) was estimated to be 11.46 mg/L (lead). Afterwards, the lead adsorption by live spirulina cells was conducted. It was observed that at the initial stage (0–12 min) the adsorption rate was so rapid that 74% of the metal was bio- logically adsorbed. The maximum biosorption capacity of live spirulina was estimated to be 0.62 mg lead per 105 alga cells.
文摘Leakage of oil and its derivatives into the soil can change the engineering behavior of soil as well as cause environmental disasters.Also,recovering the contaminated sites into their natural condition and making contaminated materials as both environmentally and geotechnically suitable construction materials need the employment of remediation techniques.Bioremediation,as an efficient,low cost and environmentalfriendly approach,was used in the case of highly plastic clayey soils.To better understand the change in geotechnical properties of highly plastic fine-grained soil due to crude oil contamination and bioremediation,Atterberg limits,compaction,unconfined compression,direct shear,and consolidation tests were conducted on natural,contaminated,and bioremediated soil samples to investigate the effects of contamination and remediation on fine-grained soil properties.Oil contamination reduced maximum dry density(MDD),optimum moisture content(OMC),unconfined compressive strength(UCS),shear strength,swelling pressure,and coefficient of consolidation of soil.In addition,contamination increased the compression and swelling indices and compressibility of soil.Bioremediation reduced soil contamination by about 50%.Moreover,in comparison with contaminated soil,bioremediation reduced the MDD,UCS,swelling index,free swelling and swelling pressure of soil,and also increased OMC,shear strength,cohesion,internal friction angle,failure strain,porosity,compression index,and settlement.Microstructural analyses showed that oil contamination does not alter the soil structure in terms of chemical compounds,elements,and constituent minerals.While it decreased the specific surface area of the soil,and the bioremediation significantly increased the mentioned parameters.Bioremediation resulted in the formation of quasi-fibrous textures and porous and agglomerated structures.As a result,oil contamination affected the mechanical properties of soil negatively,but bioremediation improved these properties.
