Microbially induced calcium carbonate precipitation(MICP)technology can induce calcium carbonate crystals with cementation and stable performance in the process of microbial metabolism or enzymization through the regu...Microbially induced calcium carbonate precipitation(MICP)technology can induce calcium carbonate crystals with cementation and stable performance in the process of microbial metabolism or enzymization through the regulation of environmental factors MICP can be used as a cementing agent to cement cohesionless sand particles to form the materials with the characteristics of higher strength,better durability and environmental friendli-ness,as well as a good engineering application prospect.In this paper,the shear strength of sand column was tested by triaxial compression tests,and the strength index was obtained.In order to further study the micro-strength mechanism and the failure process,based on the discrete element method,a numerical model of MICP cemented sand column was established considering the factors of matrix soil particle gradation,particle mor-phology,content ratio of induced calcium carbonate,pore distribution characteristics,inter-particle cementation and so on.The failure process of MICP cemented sand column under load was analysed by numerical simulation,and the reliability of the numerical model was tested by combining with the stress intensity curve of samples under test conditions.The results indicate that compared with the actual triaxial tests of MICP cemented sand column,although there are deviations in stress and strain,cohesion and internal friction angle,the numerical simulation shows similar development law and intensity amplitude,and the same failure trend.The work in this paper verifies the reliability of the numerical model and provides a theoretical basis for the subsequent analysis of the factors influencing the geotechnical mechanical properties of biomineralized materials.展开更多
Microbially induced calcite precipitation(MICP)is a recently proposed method that is environmentally friendly and has considerable potential applications in artificial biotreated geomaterials.New artificial biotreated...Microbially induced calcite precipitation(MICP)is a recently proposed method that is environmentally friendly and has considerable potential applications in artificial biotreated geomaterials.New artificial biotreated geomaterials are produced based on the MICP technology for different parent soils.The purpose of this study is to explore the strength-increase mechanism and microstmctural characteristics of the biotreated geomaterial through a series of experiments.The results show that longer mineralization time results in higher-strength biotreated geomaterial.The strength growth rate rapidly increases in the beginning and remains stable afterwards.The calcium ion content significantly increases with the extended mineralization time.When standard sand was used as a parent soil,the calcium ion content increased to a factor of 39 after 7 days.The bacterial cells with attached calcium ions serve as the nucleus of crystallization and fill the pore space.When fine sand was used as a parent soil,the calcium ion content increased to only a factor of 7 after 7 days of mineralization.The nucleus of crystallization could not normally grow because of the limited pore space.The porosity and variation in porosity are clearly affected by the parent soil.Therefore,the strength of the biotreated geomaterial is affected by the parent soil properties,mineralization time,and granular material pore space.This paper provides a basis for theory and experiments for biotreated geomaterials in future engineering practice.展开更多
The global concern surrounding the advancement of methods for treating wastewater and polluted soil has markedly increased over time.While electrochemical advanced oxidation processes(EAOPs)and biotreatments are commo...The global concern surrounding the advancement of methods for treating wastewater and polluted soil has markedly increased over time.While electrochemical advanced oxidation processes(EAOPs)and biotreatments are commonly employed technologies for remediating wastewater and polluted soil,their widespread adoption is hindered by their limitations,which include high costs associated with EAOPs and prolonged remediation time of biotreatments.In the review,we provided an overviewof EAOP technology and biotreatment,emphasizing the critical aspects involved in building a combined system.This review systematically evaluates recent research that combines EAOPswith bioremediation for treating wastewater or contaminated soil as pretreatment or post-treatment process.Research findings suggest that the combined treatment method represents a promising and competitive technology that can overcome some of the limitations of individual treatments.Additionally,we discussed the potential applications of this technology in varying levels of wastewater and soil pollution,as well as the underlying combination mechanisms.展开更多
The biotreatment of mine drainage containing dissolved manganese(Mn)using Mn(II)-oxidizing bacteria is challenging.Sequencing-batch(SBRs)and continuous-flow reactors(CFRs)packed with limestones and inoculated with the...The biotreatment of mine drainage containing dissolved manganese(Mn)using Mn(II)-oxidizing bacteria is challenging.Sequencing-batch(SBRs)and continuous-flow reactors(CFRs)packed with limestones and inoculated with the mine-drainage microbial communitywere compared to determine the removal efficiency of Mn(II)from mine drainage.Mn(II)removal in CFRs was 11.4%±0.0%(mean±standard deviation)in the first two weeks and;it slightly increased to 13.6%±0.0%after four weeks,and more than 94%of Mn(II)was removed under the steady-state treatment phase.The performance of SBRs was more effective,wherein 24.4%±0.1%of Mn was removed in the first two weeks,and in four weeks,surpassed 66.6%±0.2%.Rapid Mn(II)removal observed in the start-up of SBR resulted from higher microbial metabolic activities.The adenosine triphosphate(ATP)content of the microbial community was four-fold more than in CFR,but comparable during the steady-state phase.The Mn-oxide deposits occurring in the SBR and CFR at steady-state were mixed phases of birnessite and woodruffite,and the average Mn oxidation valence in the SBR(+3.73)was slightly higher than that in the CFR(+3.54).During the start-up treatment,the closest relatives of Methyloversatilis,Methylibium,and Curvibacter dominated the SBR,whereas putative Mn oxidizers were associated with Hyphomicrobium,Pedobacter,Pedomicrobium,Terricaulis sp.,Sulfuritalea,and Terrimonas organisms.The growth of potential Mnoxidizing genera,including Mesorhizobium,Rhodococcus,Hydrogenophaga,Terricaulis sp.,and‘Candidatus Manganitrophus-noduliformans’was observed under the steady state.The SBR operation was effective as a prior start-up treatment for mine drainage-containing Mn(II),through which the CFR performed well as posterior bio-treatment.展开更多
[Objective] To find out the process conditions and influence factors for the biotreatment of odor gases of hydrogen sulfide（H2S） and ammonia（NH3）. [Method]The degradation performances on H2 S and NH3 were investig...[Objective] To find out the process conditions and influence factors for the biotreatment of odor gases of hydrogen sulfide（H2S） and ammonia（NH3）. [Method]The degradation performances on H2 S and NH3 were investigated during the start-up and stable operation process of biofilter with ceramsites as the packing microorganisms. [Result] The biofilm formation of the biofilter system to purify the waste gas of H2 S was completed within 9 d, and the removal rate of H2 S could reach up to 99% with the initial concentration of 100-1 000 mg/m^3 and empty bed residence time（EBRT） of142-290 s. The biofilm formation of the biofilter system to purify the waste gas of NH3 was completed within 10 d with the removal rate reaching up to 94.61%.[Conclusion] Under suitable conditions, the biofilter showed high removal rates to both H2 S and NH3.展开更多
Purification of the total DNA extracted from activated sludge samples was studied. The effects of extraction buffers and lysis treatments （lysozyme, sodium dodecyl sulfate （SDS）, sonication, mechanical mill and the...Purification of the total DNA extracted from activated sludge samples was studied. The effects of extraction buffers and lysis treatments （lysozyme, sodium dodecyl sulfate （SDS）, sonication, mechanical mill and thermal shock） on yield and purity of the total DNA extracted from activated sludge were investigated. It was found that SDS and mechanical mill were the most effective ways for cell lysis, and both gave the highest DNA yields, while by SDS and thermal shock, the purest DNA extract could be obtained. The combination of SDS with other lysis treatment, such as sonication and thermal shock, could apparently increase the DNA yields but also result in severe shearing. For the purification of the crude DNA extract, polyvinyl polypyrrolidone was used for the removal of humic contaminants. Cetyltrimethyl ammonium bromide, potassium acetate and phenol/chloroform were used to remove proteins and polysaccharides from crude DNA. Crude DNA was further purified by isopropanol precipitation. Thus, a suitable protocol was proposed for DNA extraction, yielding about 49.9 mg （total DNA）/g volatile suspended solids, and the DNA extracts were successfully used in PCR amplifications for 16S rDNA and 16S rDNA V3 region. The PCR products of 16S rDNA V3 region allowed the DGGE analysis （denatured gradient gel electrophoresis） to be possible.展开更多
Four microorganism strains were isolated from coastal petroleum-polluted soil and sand samples of Bohai Sea oilfield; they were found to degrade marine oil spills effectively. The experimental results show that the de...Four microorganism strains were isolated from coastal petroleum-polluted soil and sand samples of Bohai Sea oilfield; they were found to degrade marine oil spills effectively. The experimental results show that the degradation efficiency of crude oil with these four strains （XT-4, SZ-1-25, B-4-9, BS-3-12） is 95.97%, 96.01%, 97.99% and 98.99%, respectively, in their optimum conditions. The characteristics of bacterial biodegradation are investigated. The simulation biotreatment of oil-contaminated beach sand, with an initial oil content of 5,664mg/kg-dry-sand, shows that the residual oil content is 2,700 mg/kg-dry-sand and 2,679 mg/kg-dry-sand after 170 days＇ treatment with two bacteria （B-4-9, BS-3- 12）, respectively.展开更多
Biotreatment of acidic rare earth mining wastewater via acidophilic living organisms is a promising approach owing to their high tolerance to high concentrations of rare earth elements(REEs);however,simultaneous remov...Biotreatment of acidic rare earth mining wastewater via acidophilic living organisms is a promising approach owing to their high tolerance to high concentrations of rare earth elements(REEs);however,simultaneous removal of both REEs and ammonium is generally hindered since most acidophilic organisms are positively charged.Accordingly,immobilization of acidophilic Galdieria sulphuraria(G.sulphuraria)by calcium alginate to improve its affinity to positively charged REEs has been used for simultaneous bioremoval of REEs and ammonium.The results indicate that 97.19%,96.19%,and 98.87%of La,Y,and Sm,respectively,are removed by G.sulphuraria beads(GS-BDs).The adsorption of REEs by calcium alginate beads(BDs)and GS-BDs is well fitted by both pseudo first-order(PFO)and pseudo second-order(PSO)kinetic models,implying that adsorption of REEs involves both physical adsorption caused by affinity of functional groups such as-COO-and -OH and chemical adsorption based on ion exchange of Ca^(2+) with REEs.Notably,GS-BDs exhibit high tolerance to La,Y,and Sm with maximum removal efficiencies of 97.9%,96.6%,and 99.1%,respectively.Furthermore,the ammonium removal efficiency of GS-BDs is higher than that of free G.sulphuraria cells at an initial ammonium concentration of 100 mg L^(-1),while the efficiency decreases when initial concentration of ammonium is higher than 150 mg L^(-1).Last,small size of GS-BDs favors ammonium removal because of their lower mass transfer resistance.This study achieves simultaneous removal of REEs and ammonium from acidic mining drainage,providing a potential strategy for biotreatment of REE tailing wastewater.展开更多
基金sponsored by the National Natural Science Foundation of China(Grant No.12002173,12262027)Research start-up project of Inner Mongolia University of Technology(No.2200000924)key Lab.of University of Geological Hazards and Geotechnical Engineering Defense in Sandy and Drought Regions,Inner Mongolia Autonomous.
文摘Microbially induced calcium carbonate precipitation(MICP)technology can induce calcium carbonate crystals with cementation and stable performance in the process of microbial metabolism or enzymization through the regulation of environmental factors MICP can be used as a cementing agent to cement cohesionless sand particles to form the materials with the characteristics of higher strength,better durability and environmental friendli-ness,as well as a good engineering application prospect.In this paper,the shear strength of sand column was tested by triaxial compression tests,and the strength index was obtained.In order to further study the micro-strength mechanism and the failure process,based on the discrete element method,a numerical model of MICP cemented sand column was established considering the factors of matrix soil particle gradation,particle mor-phology,content ratio of induced calcium carbonate,pore distribution characteristics,inter-particle cementation and so on.The failure process of MICP cemented sand column under load was analysed by numerical simulation,and the reliability of the numerical model was tested by combining with the stress intensity curve of samples under test conditions.The results indicate that compared with the actual triaxial tests of MICP cemented sand column,although there are deviations in stress and strain,cohesion and internal friction angle,the numerical simulation shows similar development law and intensity amplitude,and the same failure trend.The work in this paper verifies the reliability of the numerical model and provides a theoretical basis for the subsequent analysis of the factors influencing the geotechnical mechanical properties of biomineralized materials.
基金This study was sponsored by the National Natural Science Foundation of China(Grant Nos.51668050,51968057)the Natural Science Foundation of Inner Mongolia Autonomous Region of China(Nos.2018MS01014,2019MS05075).
文摘Microbially induced calcite precipitation(MICP)is a recently proposed method that is environmentally friendly and has considerable potential applications in artificial biotreated geomaterials.New artificial biotreated geomaterials are produced based on the MICP technology for different parent soils.The purpose of this study is to explore the strength-increase mechanism and microstmctural characteristics of the biotreated geomaterial through a series of experiments.The results show that longer mineralization time results in higher-strength biotreated geomaterial.The strength growth rate rapidly increases in the beginning and remains stable afterwards.The calcium ion content significantly increases with the extended mineralization time.When standard sand was used as a parent soil,the calcium ion content increased to a factor of 39 after 7 days.The bacterial cells with attached calcium ions serve as the nucleus of crystallization and fill the pore space.When fine sand was used as a parent soil,the calcium ion content increased to only a factor of 7 after 7 days of mineralization.The nucleus of crystallization could not normally grow because of the limited pore space.The porosity and variation in porosity are clearly affected by the parent soil.Therefore,the strength of the biotreated geomaterial is affected by the parent soil properties,mineralization time,and granular material pore space.This paper provides a basis for theory and experiments for biotreated geomaterials in future engineering practice.
基金supported by the National Natural Science Foundation of China(No.51709103)the Natural Science Foundation of Hunan Province,China(Nos.2018JJ3242 and 2021JJ30362)the Science and Technology Innovation Leading Plan of High Tech Industry in Hunan Province(No.2021GK4055).
文摘The global concern surrounding the advancement of methods for treating wastewater and polluted soil has markedly increased over time.While electrochemical advanced oxidation processes(EAOPs)and biotreatments are commonly employed technologies for remediating wastewater and polluted soil,their widespread adoption is hindered by their limitations,which include high costs associated with EAOPs and prolonged remediation time of biotreatments.In the review,we provided an overviewof EAOP technology and biotreatment,emphasizing the critical aspects involved in building a combined system.This review systematically evaluates recent research that combines EAOPswith bioremediation for treating wastewater or contaminated soil as pretreatment or post-treatment process.Research findings suggest that the combined treatment method represents a promising and competitive technology that can overcome some of the limitations of individual treatments.Additionally,we discussed the potential applications of this technology in varying levels of wastewater and soil pollution,as well as the underlying combination mechanisms.
基金funded by the JOGMEC Research Grant and JSPS KAKENHI(No.JP21H03636).
文摘The biotreatment of mine drainage containing dissolved manganese(Mn)using Mn(II)-oxidizing bacteria is challenging.Sequencing-batch(SBRs)and continuous-flow reactors(CFRs)packed with limestones and inoculated with the mine-drainage microbial communitywere compared to determine the removal efficiency of Mn(II)from mine drainage.Mn(II)removal in CFRs was 11.4%±0.0%(mean±standard deviation)in the first two weeks and;it slightly increased to 13.6%±0.0%after four weeks,and more than 94%of Mn(II)was removed under the steady-state treatment phase.The performance of SBRs was more effective,wherein 24.4%±0.1%of Mn was removed in the first two weeks,and in four weeks,surpassed 66.6%±0.2%.Rapid Mn(II)removal observed in the start-up of SBR resulted from higher microbial metabolic activities.The adenosine triphosphate(ATP)content of the microbial community was four-fold more than in CFR,but comparable during the steady-state phase.The Mn-oxide deposits occurring in the SBR and CFR at steady-state were mixed phases of birnessite and woodruffite,and the average Mn oxidation valence in the SBR(+3.73)was slightly higher than that in the CFR(+3.54).During the start-up treatment,the closest relatives of Methyloversatilis,Methylibium,and Curvibacter dominated the SBR,whereas putative Mn oxidizers were associated with Hyphomicrobium,Pedobacter,Pedomicrobium,Terricaulis sp.,Sulfuritalea,and Terrimonas organisms.The growth of potential Mnoxidizing genera,including Mesorhizobium,Rhodococcus,Hydrogenophaga,Terricaulis sp.,and‘Candidatus Manganitrophus-noduliformans’was observed under the steady state.The SBR operation was effective as a prior start-up treatment for mine drainage-containing Mn(II),through which the CFR performed well as posterior bio-treatment.
基金Supported by the Climbing Program for Graduates of Guangdong Province~~
文摘[Objective] To find out the process conditions and influence factors for the biotreatment of odor gases of hydrogen sulfide（H2S） and ammonia（NH3）. [Method]The degradation performances on H2 S and NH3 were investigated during the start-up and stable operation process of biofilter with ceramsites as the packing microorganisms. [Result] The biofilm formation of the biofilter system to purify the waste gas of H2 S was completed within 9 d, and the removal rate of H2 S could reach up to 99% with the initial concentration of 100-1 000 mg/m^3 and empty bed residence time（EBRT） of142-290 s. The biofilm formation of the biofilter system to purify the waste gas of NH3 was completed within 10 d with the removal rate reaching up to 94.61%.[Conclusion] Under suitable conditions, the biofilter showed high removal rates to both H2 S and NH3.
基金This work was supported by the China Postdoctoral Science Foundation(No.20060390060).
文摘Purification of the total DNA extracted from activated sludge samples was studied. The effects of extraction buffers and lysis treatments （lysozyme, sodium dodecyl sulfate （SDS）, sonication, mechanical mill and thermal shock） on yield and purity of the total DNA extracted from activated sludge were investigated. It was found that SDS and mechanical mill were the most effective ways for cell lysis, and both gave the highest DNA yields, while by SDS and thermal shock, the purest DNA extract could be obtained. The combination of SDS with other lysis treatment, such as sonication and thermal shock, could apparently increase the DNA yields but also result in severe shearing. For the purification of the crude DNA extract, polyvinyl polypyrrolidone was used for the removal of humic contaminants. Cetyltrimethyl ammonium bromide, potassium acetate and phenol/chloroform were used to remove proteins and polysaccharides from crude DNA. Crude DNA was further purified by isopropanol precipitation. Thus, a suitable protocol was proposed for DNA extraction, yielding about 49.9 mg （total DNA）/g volatile suspended solids, and the DNA extracts were successfully used in PCR amplifications for 16S rDNA and 16S rDNA V3 region. The PCR products of 16S rDNA V3 region allowed the DGGE analysis （denatured gradient gel electrophoresis） to be possible.
基金This work was financially supported by the National Natural Science Foundation of China (No.40472152)
文摘Four microorganism strains were isolated from coastal petroleum-polluted soil and sand samples of Bohai Sea oilfield; they were found to degrade marine oil spills effectively. The experimental results show that the degradation efficiency of crude oil with these four strains （XT-4, SZ-1-25, B-4-9, BS-3-12） is 95.97%, 96.01%, 97.99% and 98.99%, respectively, in their optimum conditions. The characteristics of bacterial biodegradation are investigated. The simulation biotreatment of oil-contaminated beach sand, with an initial oil content of 5,664mg/kg-dry-sand, shows that the residual oil content is 2,700 mg/kg-dry-sand and 2,679 mg/kg-dry-sand after 170 days＇ treatment with two bacteria （B-4-9, BS-3- 12）, respectively.
基金financial support from the Anhui Provincial Natural Science Foundation-China(1908085QB70)the Natural Science Fund of the Education Department of Anhui Province(KJ2021A0031)+1 种基金Anhui University(Startup Fund-China Y040418343)the Horizontal Cooperation Project of Fuyang Municipal Government-Fuyang Normal University(SXHZ202102)。
文摘Biotreatment of acidic rare earth mining wastewater via acidophilic living organisms is a promising approach owing to their high tolerance to high concentrations of rare earth elements(REEs);however,simultaneous removal of both REEs and ammonium is generally hindered since most acidophilic organisms are positively charged.Accordingly,immobilization of acidophilic Galdieria sulphuraria(G.sulphuraria)by calcium alginate to improve its affinity to positively charged REEs has been used for simultaneous bioremoval of REEs and ammonium.The results indicate that 97.19%,96.19%,and 98.87%of La,Y,and Sm,respectively,are removed by G.sulphuraria beads(GS-BDs).The adsorption of REEs by calcium alginate beads(BDs)and GS-BDs is well fitted by both pseudo first-order(PFO)and pseudo second-order(PSO)kinetic models,implying that adsorption of REEs involves both physical adsorption caused by affinity of functional groups such as-COO-and -OH and chemical adsorption based on ion exchange of Ca^(2+) with REEs.Notably,GS-BDs exhibit high tolerance to La,Y,and Sm with maximum removal efficiencies of 97.9%,96.6%,and 99.1%,respectively.Furthermore,the ammonium removal efficiency of GS-BDs is higher than that of free G.sulphuraria cells at an initial ammonium concentration of 100 mg L^(-1),while the efficiency decreases when initial concentration of ammonium is higher than 150 mg L^(-1).Last,small size of GS-BDs favors ammonium removal because of their lower mass transfer resistance.This study achieves simultaneous removal of REEs and ammonium from acidic mining drainage,providing a potential strategy for biotreatment of REE tailing wastewater.
