Mycelia pellet formed spontaneously in the process of cultivation was exploited as a biological carrier for whole-cell immobilization due to its unique structural characteristic. An innovative two-species whole-cell i...Mycelia pellet formed spontaneously in the process of cultivation was exploited as a biological carrier for whole-cell immobilization due to its unique structural characteristic. An innovative two-species whole-cell im- mobilization system was achieved by inoculating the marine-derived fungus Pestalotiopsis sp. J63 spores into cul- ture medium containing another fungus Penicillium janthinellum P1 pre-grown mycelia pellets for 2 days without any pretreatment. In order to evaluate the biological degradation capacity of this novel constructed immobilization system, the immobilized pellets were applied to treat paper mill effluent and decolorize dye Azure B. The use of the constructed immobilization system in the effluent resulted in successful and rapid biodegradation of numerous in- soluble fine fibers. The optimum conditions of immobilized procedure for maximum biodegradation capacity were determined using orthogonal design with biomass of P1 pellets 10 g （wet mass）, concentration of J63 spore 2x109 mlq, and immobilization time 2 d. The results demonstrate that immobilized pellets have more than 99% biodegradation capacity in a ten-hour treatment process. The kinetics of biodegradation fits the Michaelis-Menten equation well. Besides, the decolorization capability of immobilized pellets is more superior than that of P1 mycelia pellets. Overall, the present study offers a simple and reproducible way to construct a two-species whole-cell immobiliza- tion system for sewage treatment.展开更多
Converting renewable cellulose into glucose via cellulase catalysis for further production of biofuel has been recognized as one of the most promising ways for solving energy crisis.However,the hydrolysis performance ...Converting renewable cellulose into glucose via cellulase catalysis for further production of biofuel has been recognized as one of the most promising ways for solving energy crisis.However,the hydrolysis performance of immobilized cellulase was not satisfactory for practical application due to the reduced catalytic efficiency and lack of β-glucosidase(BG)component in cellulase.Here,a facile method was developed to sequentially co-immobilize BG and cellulase by polymeric microparticles with hierarchical structure.In this strategy,BG was firstly entrapped into the cross-linked poly(ethylene glycol)(PEG)microparticles via inverse emulsion polymerization initiated by isopropyl thioxanthone(ITX)under the irradiation of visible light,leaving the formed ITX semi-pinacol(ITXSP)dormant groups on surface of BG-loaded microparticles,which could be further activated by visible light irradiation and initiated a graft polymerization to introduce poly(acrylic acid)(PAA)brush on the PEG core.After that,cellulase was covalently bonded on the PAA chains via carbodiimide reaction.The synergic effect of BG and cellulase was verified in the dual enzyme immobilization system,which led to a better stability at a wide range of temperature and pH than free enzymes.The dual enzymes system exhibited excellent reusability,which could retain 75%and 57%of the initial activity after 10 cycles of hydrolysis of carboxyl methyl cellulose and 5 cycles of hydrolysis of filter paper,respectively,indicative of the potential in biofuel areas in a cost-effective manner.展开更多
The efficiency and mechanism of hydrous iron oxide(HFO)and HFO/calcite mixture to inactivate the phosphorus in the overlying water(OW)/sediment system under the feed adding condition were explored,and the effect of HF...The efficiency and mechanism of hydrous iron oxide(HFO)and HFO/calcite mixture to inactivate the phosphorus in the overlying water(OW)/sediment system under the feed adding condition were explored,and the effect of HFO and HFO/calcite mixture addition on the diversity,composition and function of bacterial communities in the sediment was examined.HFO and HFO/calcite mixture direct addition can effectively lower the concentration of soluble reactive phosphorus(RSP)and diffusion gradient in thin film-unstable phosphorus(PD GT)in OW and inactivate the P DGTin the upper sediment.The elimination efficiencies of RSP by the direct HFO and HFO/calcite mixture addition were 48.9%-97.0%and 42.4%-95.4%,respectively.The alteration in the addition mode from the one-time to multiple direct addition was beneficial to the immobilization of RSP and PD GTin OW and P DGTin the upper sediment by HFO and HFO/calcite mixture under the feed input condition in the long run.Permeable fabric wrapping reduced the inactivation efficiency of RSP in OW by HFO and HFO/calcite mixture,but it made the recycling of these materials possible.Most of P immobilized by HFO and HFO/calcite mixture was relatively or very stable.After the HFO and HFO/calcite mixture addition,the composition of bacterial communities in the surface sediment changed.However,the bacterial communities in the amended sediments still can perform good ecological function.Our findings suggest that HFO and HFO/calcite mixture are promising phosphorus-immobilization materials for the inactivation of RSP and PD GTin OW and PD GTin the upper sediment under the feed inputting condition.展开更多
[Objective] The aim was to seek effective soil remediation technologies suitable for soils slightly or moderately polluted. [Method] In-situ leaching-immobi- lization was used to research remediation soil and vegetabl...[Objective] The aim was to seek effective soil remediation technologies suitable for soils slightly or moderately polluted. [Method] In-situ leaching-immobi- lization was used to research remediation soil and vegetable contaminated by lead in vegetable bases in Chongqing. [Result] By tartaric acid-based leaching-sodium sulphide-based immobilization, vegetable Pb reduction rate was 46.4%, soil Pb reduction rate was 8.45% and Pb immobilization rate was 9.3% in deeper horizons. EDTA leaching did reduce lead content in vegetables, but reduced vegetable yield simultaneously. [Conclusion] The coupling remediation technology brought heavy metal contents down in vegetables without affecting productions. Therefore, it guarantees vegetable safety and reduces vegetable farmer＇s economic loss. It is a remediation technology suitable for soils slightly or moderately contaminated by heavy metals.展开更多
[Objective] The aim was to study the immobilization of laccase from Canoderma lucidum in three different sol-gel systems to find out the optimum ma- terials for laccase immobilization. [ Method ] Laccase from G. lucid...[Objective] The aim was to study the immobilization of laccase from Canoderma lucidum in three different sol-gel systems to find out the optimum ma- terials for laccase immobilization. [ Method ] Laccase from G. lucidum LYL 263 was immobilized in sodium alginate-gelatin, sodium alginate-chitosan and sodium alginate-gelatin-chitosan sol-gel systems, respectively; and the laccase activity was preliminarily analyzed. [ Result] The activity of laccase immobilized in sodium alginate-gelatin-chitosan was 2.14 folds and 2.75 folds respectively, compared to sodium alginate-gelatin and sodium alginate-chitosan; and this optimum system contained sodium alginate 2.0% , gelatin 1.0%, chitosan 0.3% and calcium chloride 56%. Benzoic acid was firstly used to embed immobilized laccase in this study, and single-factor experiments revealed that the activity of laccase could be effectively improved by suitable content of benzoic acid. The optimal conditions for laccase immobilization in the system were be^oie acid 2 retool/L, glutaraldehyde 0.32%, cross-linking reaction time 50 rain and enzyme concentration 10.0% ; and then the activity of the immobilized enzyme reached 635.7 U/g with these conditions. The thermal stability of the immobilized laccase was higher than free lac- case, and the activity of immobilized enzyme treated by freeze-drying was 1.59 folds compared to the non-freeze-dried, but the freeze-dried immobilized laccase had poor operational stability. [ Conclusion] The compositions of the material had significant influence on laccase immobilization and this study will provide reference to select materials for immobilization of laccase from G. lacidum LYL 263.展开更多
Chromium is an important resource in strategic metals.Different from most studies focusing on the bio-reduction of hexavalent chromium[Cr(VI)],this study aims to achieve the immobilization and recovery of chromium usi...Chromium is an important resource in strategic metals.Different from most studies focusing on the bio-reduction of hexavalent chromium[Cr(VI)],this study aims to achieve the immobilization and recovery of chromium using a sequencing batch biofilm reactor.Results showed that Cr(VI) removal efficiency remained more than 99%,and 97%of reduced Cr(III) was immobilized in the biofilm.Immobilization zone,chromium forms and extracellular polymeric substances composition changes were combined to reveal the mechanism of Cr(VI) reduction and immobilization.The chromium distribution in biofilm demonstrated that intercellular layer was the main active zone with an immobilization amount of 891.70±126.32 mg/g-VSS.The reduced products analysis confirmed that trivalent chromium[Cr(III)]chelated with carboxyl,amino and other functional groups and immobilized in the form of organic Cr(III).The digestion method realized a chromium recovery efficiency of 74.59%.This study provides an alternative method for the bioremediation and resources recovery in chromium polluted wastewater.展开更多
Objective: To evaluate the effectiveness of a patient-specific immobilization and positioning device in prostate radiotherapy. Methods: Eighty patients were immobilized and positioned by a patient-specific device. Pro...Objective: To evaluate the effectiveness of a patient-specific immobilization and positioning device in prostate radiotherapy. Methods: Eighty patients were immobilized and positioned by a patient-specific device. Prostate translations and rotations were estimated from daily cone beam computed tomography scans using a contour-based approach assisted by auto-registration and quantified by the group mean GM, systematic Σ and random σ' errors. Dosimetric impacts of residual prostate rotations where the translation errors were corrected were evaluated by robustness plan analysis. Results: Using the patient-specific immobilization alone without online image-guidance, the GM, Σ and σ' of the prostate translations were 0.8, 1.7, and 1.5 mm (left-right;LR), 0.8, 2.1, and 1.9 mm (superior-inferior;SI), and 0.5, 1.7 and 1.5 mm (anterior-posterior;AP), while for the prostate rotations they were 0.0°, 0.6°, and 0.7°(pitch), 0.2°, 0.5°, and 0.6°(roll), and 0.2°, 0.5°, and 0.6°(yaw). The resulting van Herk’s margin was 5.8 (LR), 7.3 (SI) and 5.8 (AP) mm. With adaptive online image-guidance based on estimates from the first 5 fractions, Σ were reduced by 0.7 - 1.2 mm for the prostate translations, resulting in a margin reduction by 2 - 3.5 mm. Changes of Σ and σ' in the prostate rotations were insignificant regardless of translation corrections. Dosimetric impacts of residual rotation errors were negligible if a 2 mm margin was applied. Conclusions: Our patient-specific immobilization system can effectively limit the prostate translations and rotations, which is important without 6D treatment couches or using ultrasound image-guidance without rotational corrections.展开更多
Arsenic(As)pollution in soils is a pervasive environmental issue.Biochar immobilization offers a promising solution for addressing soil As contamination.The efficiency of biochar in immobilizing As in soils primarily ...Arsenic(As)pollution in soils is a pervasive environmental issue.Biochar immobilization offers a promising solution for addressing soil As contamination.The efficiency of biochar in immobilizing As in soils primarily hinges on the characteristics of both the soil and the biochar.However,the influence of a specific property on As immobilization varies among different studies,and the development and application of arsenic passivation materials based on biochar often rely on empirical knowledge.To enhance immobilization efficiency and reduce labor and time costs,a machine learning(ML)model was employed to predict As immobilization efficiency before biochar application.In this study,we collected a dataset comprising 182 data points on As immobilization efficiency from 17 publications to construct three ML models.The results demonstrated that the random forest(RF)model outperformed gradient boost regression tree and support vector regression models in predictive performance.Relative importance analysis and partial dependence plots based on the RF model were conducted to identify the most crucial factors influencing As immobilization.These findings highlighted the significant roles of biochar application time and biochar pH in As immobilization efficiency in soils.Furthermore,the study revealed that Fe-modified biochar exhibited a substantial improvement in As immobilization.These insights can facilitate targeted biochar property design and optimization of biochar application conditions to enhance As immobilization efficiency.展开更多
Arsenic-contaminated groundwater is widely used in agriculture.To meet the increasing demand for safe water in agriculture,an efficient and cost-effective method for As removal from groundwater is urgently needed.We h...Arsenic-contaminated groundwater is widely used in agriculture.To meet the increasing demand for safe water in agriculture,an efficient and cost-effective method for As removal from groundwater is urgently needed.We hypothesized that Fe(oxyhydr)oxide(FeOOH)minerals precipitated in situ from indigenous Fe in groundwater may immobilize As,providing a solution for safely using As-contaminated groundwater in irrigation.To confirm this hypothesis and identify the controlling mechanisms,we comprehensively evaluated the transport,speciation changes,and immobilization of As and Fe in agricultural canals irrigated using As-contaminated groundwater.The efficiently removed As and Fe in the canals accumulated in shallow sediment rather than subsurface sediment.Linear combination fitting(LCF)analysis of X-ray absorption near edge spectroscopy(XANES)indicated that As(Ⅴ)was the dominant As species,followed by As(Ⅲ),and therewas no FeAsO_(4) precipitate.Sequential extraction revealed higher contents of amorphous FeOOH and associated As in shallower sediment than in the subsurface layer.Stoichiometric molar ratio calculations,SEM-EDS,FTIR,and fluorescence spectroscopy collectively demonstrated that the microbial reductive dissolution of amorphous FeOOH proceeded via reactive dissolved organic matter(DOM)consumption in subsurface anoxic porewater environment facilitating high labile As,whereas in surface sediment,the in situ-generated amorphous FeOOH was stable and strongly inhibited As release via adsorption.In summary,groundwater Fe^(2+)can efficiently precipitate in benthic surface sediment as abundant amorphous FeOOH,which immobilizes most of the dissolved As,protecting agricultural soil from contamination.This field research supports the critical roles of the phase and reactivity of in situ-generated FeOOH in As immobilization and provides new insight into the sustainable use of contaminated water.展开更多
Two strains of Fe/Mn oxidizing bacteria tolerant to high concentrations of multiple heavy metal(loid)s and efficient decontamination for them were screened.The surface of the bio-Fe/Mn oxides produced by the oxidation...Two strains of Fe/Mn oxidizing bacteria tolerant to high concentrations of multiple heavy metal(loid)s and efficient decontamination for them were screened.The surface of the bio-Fe/Mn oxides produced by the oxidation of Fe(II)and Mn(II)by Pseudomonas taiwanensis(marked as P4)and Pseudomonas plecoglossicida(marked as G1)contains rich reactive oxygen functional groups,which play critical roles in the removal efficiency and immobilization of heavymetal(loid)s in co-contamination system.The isolated strains P4 and G1 can growwell in the following environments:pH 5-9,NaCl 0-4%,and temperature 20-30℃.The removal efficiencies of Fe,Pb,As,Zn,Cd,Cu,and Mn are effective after inoculation of the strains P4 and G1 in the simulated water system(the initial concentrations of heavy metal(loid)were 1 mg/L),approximately reaching 96%,92%,85%,67%,70%,54%and 15%,respectively.The exchangeable and carbonate bound As,Cd,Pb and Cu are more inclined to convert to the Fe-Mn oxide bound fractions in P4 and G1 treated soil,thereby reducing the phytoavailability and bioaccessible of heavy metal(loid)s.This research provides alternatives method to treat water and soil containing high concentrations of multi-heavy metal(loid)s.展开更多
Coking wastewater,characterized by high biological toxicity,poses significant challenges for traditional biological treatment methods.This study developed a novel in-situ immobilized photocatalytic-algae-bacteria cons...Coking wastewater,characterized by high biological toxicity,poses significant challenges for traditional biological treatment methods.This study developed a novel in-situ immobilized photocatalytic-algae-bacteria consortia(P-ABC)system using a polyether polyurethane sponge as a carrier,aiming to enhance biological treatment efficiency for actual coking wastewater.Results showed a 16.8%increase in algal density(up to 1.51×10^(5) cells/mL)in the P-ABC system compared to non-coupled controls,with significantly improved microbial metabolic activity,confirming the carrier's exceptional biocompatibility.Compared to standalone algae-bacteria consortia systems,the P-ABC system achieved higher removal efficiencies for chemical oxygen demand(COD_(Cr),19.8%),total organic carbon(TOC,21.2%),and total nitrogen(TN,30.4%).These findings validate the system's potential for improving stable and efficient treatment of industrial wastewater.Furthermore,this study offers insights into bio-enhanced treatment technologies and provides a reference pathway for integrating advanced oxidation and biological processes.展开更多
This study demonstrates the valorization of macadamia nutshells,a lignocellulosic agricultural waste,as both a carbon source for amylase production and a support matrix for enzyme immobilization.Under optimized solid-...This study demonstrates the valorization of macadamia nutshells,a lignocellulosic agricultural waste,as both a carbon source for amylase production and a support matrix for enzyme immobilization.Under optimized solid-state fermentation conditions,Aspergillus niger ICP2 synthesized amylase with a peak activity of 0.312 U/mL after 72 hours.A four-step purification process of the crude enzyme extract resulted in a 188.54-fold increase in specific activity,albeit with a final recovery yield of 0.0031%.In parallel,nutshells were carbonized at 600℃,700℃,and 800℃,then chemically activated with ZnCl_(2).The carbon derived at 700℃ exhibited superior physicochemical characteristics,including enhanced porosity and increased availability of functional groups,which enabled effective enzyme adsorption,improved catalytic performance,and enhanced reusability.Immobilized amylase on this support retained approximately 30% of its initial activity after five hydrolysis cycles,demonstrating moderate operational reusability and potential for repeated use in bioprocesses.In contrast,carbon materials from 600℃ and 800℃ showed lower stability and enzyme performance.These findings highlight the critical role of carbonization conditions in designing effective immobilization matrices and underscore the potential of macadamia nutshells as a renewable and sustainable resource for biocatalyst development.This“biowaste-to-biocatalyst”strategy exemplifies a circular bioeconomy model with implications for green chemistry,industrial biocatalysis,and environmental sustainability.展开更多
As an energy and carbon saving process for nitrogen removal from wastewater,the partial nitrification and denitrification process(PN/D)has been extensively researched.However,achieving stable PNinmunicipalwastewater h...As an energy and carbon saving process for nitrogen removal from wastewater,the partial nitrification and denitrification process(PN/D)has been extensively researched.However,achieving stable PNinmunicipalwastewater has always been challenging.In this study,a gel immobilized PN/D nitrogen removal process(GI-PN/D)was established.A 94 days pilot-scale experiment was conducted using real municipal wastewater with an ammonia concentration of 43.5±5.3mg N/L at a temperature range of 11.3–28.7◦C.The nitrogen removal performance and associated pathways,shifts in the microbial community as well as sludge yield were investigated.The results were as follows:the effluent TN and COD were 0.6±0.4mg/L and 31.1±3.8 mg/L respectively,and the NAR exceeding 95%.GI-PN/D achieved deep nitrogen removal ofmunicipalwastewater through stable PN without taking any othermeasures.The primary pathways for nitrogen removal were identified as denitrification,simultaneous nitrification-denitrification,and aerobic denitrification.High-throughput sequencing analysis revealed that the immobilized fillers facilitated the autonomous enrichment of functional bacteria in each reactor,effectively promoting the dominance and stability of the microbial communities.In addition,GI-PN/D had the characteristic of low sludge yield,with an average sludge yield of 0.029 kg SS/kg COD.This study provides an effective technical for nitrogen removal from municipal wastewater through PN.展开更多
With the rapid development of nuclear energy,the removal of radioactive iodine generated during spent fuel reprocessing has become increasingly important.Based on the unique straw-like structure of populus tomentosa f...With the rapid development of nuclear energy,the removal of radioactive iodine generated during spent fuel reprocessing has become increasingly important.Based on the unique straw-like structure of populus tomentosa fiber(PTF)and the highly active iodine vapor capture ability of zero-valent silver nanoparticles(PTF@Ag^(0)NP),an Ag^(0)NP composite functional material with highly efficient iodine vapor capture capability was synthesized from biowaste PTF through ultrasonic and hightemperature hydrothermal methods in this study.The iodine capture experiment demonstrated that PTF@Ag^(0)NP exhibits rapid iodine capture efficiency,reaching dynamic equilibrium within 4 h and a maximum capture capacity of 1008.1 mg/g.Density functional theory calculations show that PTF@Ag^(0)NP exhibits extremely high chemical reactivity toward iodine,with a reaction binding energy of-2.88 e V.Additionally,the molecular dynamics of PTF@Ag^(0)NP indicate that there is no atomic displacement at 77?C,indicating the excellent temperature stability of the material at the operating temperature.The capture mechanism suggests that iodine vapor primarily reacts with Ag^(0)NP to form Ag I,and that the hydroxyl groups in PTF can also effectively capture iodine vapor by adsorption induction.In conclusion,PTF@Ag^(0)NP is expected to be an effective candidate adsorbent material for removing radioactive iodine vapor from exhaust gases during spent fuel reprocessing.展开更多
In photocatalytic water treatment processes,the particulate photocatalysts are typically immobilized on membrane,through either chemical/physical loading onto the surface or directly embedding in the membrane matrix.H...In photocatalytic water treatment processes,the particulate photocatalysts are typically immobilized on membrane,through either chemical/physical loading onto the surface or directly embedding in the membrane matrix.However,these immobilization strategies inevitably compromise the interfacial mass diffusion and cause activity decline relative to the suspended catalyst.Here,we propose a binder-free surface immobilization strategy for fabrication of high-activity photocatalytic membrane.Through a simple dimethylformamide(DMF)treatment,the nanofibers of polyvinylidene fluoride membrane were softened and stretched,creating enlarged micropores to efficiently capture the photocatalyst.Subsequently,the nanofibers underwent shrinking during DMF evaporation,thus firmly strapping the photocatalyst microparticles on the membrane surface.This surface self-bounded photocatalytic membrane,with firmly bounded yet highly exposed photocatalyst,exhibited 4.2-fold higher efficiency in hydrogen peroxide(H_(2)O_(2))photosynthesis than the matrix-embedded control,due to improved O_(2)accessibility and H_(2)O_(2)diffusion.It even outperformed the suspension photocatalytic system attributed to alleviated H_(2)O_(2)decomposition at the hydrophobic surface.When adopted for UV-based water treatment,the photocatalytic system exhibited tenfold faster micropollutants photodegradation than the catalyst-free control and demonstrated superior robustness for treating contaminated tap water,lake water and secondary wastewater effluent.This immobilization strategy can also be extended to the fabrication of other photocatalytic membranes with diverse catalyst types and membrane substrate.Overall,our work opens a facile avenue for fabrication of high-performance photocatalytic membranes,which may benefit advanced oxidation water purification application and beyond.展开更多
Endocrine disruptors such as bisphenol A(BPA)adversely affect the environment and human health.Laccases are used for the efficient biodegradation of various persistent organic pollutants in an environmentally safe man...Endocrine disruptors such as bisphenol A(BPA)adversely affect the environment and human health.Laccases are used for the efficient biodegradation of various persistent organic pollutants in an environmentally safe manner.However,the direct application of free laccases is generally hindered by short enzyme lifetimes,non-reusability,and the high cost of a single use.In this study,laccases were immobilized on a novel magnetic threedimensional poly(ethylene glycol)diacrylate(PEGDA)-chitosan(CS)inverse opal hydrogel(LAC@MPEGDA@CS@IOH).The immobilized laccase showed significant improvement in the BPA degradation performance and superior storage stability compared with the free laccase.91.1%of 100 mg/L BPA was removed by the LAC@MPEGDA@CS@IOH in 3 hr,whereas only 50.6%of BPA was removed by the same amount of the free laccase.Compared with the laccase,the outstanding BPA degradation efficiency of the LAC@MPEGDA@CS@IOH was maintained over a wider range of pH values and temperatures.Moreover,its relative activity of was maintained at 70.4%after 10 cycles,and the system performed well in actual water matrices.This efficientmethod for preparing immobilized laccases is simple and green,and it can be used to further develop ecofriendly biocatalysts to remove organic pollutants from wastewater.展开更多
Arsenic(As)contamination of groundwater is a serious global issue requiring effective and sustainable remediation strategies.For long-term As immobilization,this study explores the potential of in-situ magnetite preci...Arsenic(As)contamination of groundwater is a serious global issue requiring effective and sustainable remediation strategies.For long-term As immobilization,this study explores the potential of in-situ magnetite precipitation,induced by anaerobic nitrate-reducing Fe(II)-oxidizing(NRFO)bacteria.A nitrate-intercalated layered double hydroxide(NO_(3)^(-)MgFe LDH)was introduced to provide nitrate as an electron acceptor for Fe(II)bio-oxidation and serve as an iron-based precursor in magnetite formation.The experimental results showed that NO_(3)^(-)MgFe LDH was transformed into green rust(GR)in the presence of Fe(II)and HCO_(3)^(-).Meanwhile,0.5 g/L of NO_(3)^(-)MgFe LDH released cumulatively about 1.21 mM of nitrate within 12 h,promoting the transformation of GR into magnetite induced by Acidovorax sp.BoFeN1.As a result,the aqueous As concentration decreased from 2 mg/L to<0.008 mg/L,with approximately 70%of As confined in recalcitrant Fe oxides,suggesting high potential for long-term As immobilization.Environmental factors influenced the transformation process:a lower Fe(II)concentration(0.5 mM)delayed GR formation,while varying HCO_(3)^(-)concentrations(2.5-10 mM)had minimal effect.Subsequently,an elevated As level(5 mg/L)inhibited the bio-formation of magnetite,leading to lepidocrocite as the dominant mineral phase.Given the stability of magnetite,this study provides a cost-effective and environmentally friendly strategy for the durable in-situ remediation of As-contaminated groundwater.展开更多
The microbial immobilization method using polyvinyl alcohol （PVA） gel as an immobilizing material was improved and used for entrapment of activated sludge. The oxygen uptake rate （OUR） was used to characterize the...The microbial immobilization method using polyvinyl alcohol （PVA） gel as an immobilizing material was improved and used for entrapment of activated sludge. The oxygen uptake rate （OUR） was used to characterize the biological activity of immobilized activated sludge. Three kinds of PVA-immobilized particles of activated sludge, that is, PVA-boric acid beads, PVA-sodium nitrate beads and PVA-orthophosphate beads were prepared, and their biological activity was compared by measuring the OUR value. The bioactivity of both autotrophic and heterotrophic microorganisms of activated sludge was determined using different synthetic wastewater media （containing 250 mg/L COD and 25 mg/L NH4^＋ -N）. The experimental results showed that the bioactivity and stability of the three kinds of immobilized activated sludge was greatly improved after activation. With respect of the bioactivity and the mechanical stability, the PVA-orthophosphate method may be a promising and economical technique for microbial immobilization.展开更多
Activated sludge was immobilized into Ca-alginate beads via entrapment, and biosorption of three heavy metal ions, copper(Ⅱ), zinc(Ⅱ), and chromimum(Ⅱ), from aqueous solution in the concentration range of 10\_100 m...Activated sludge was immobilized into Ca-alginate beads via entrapment, and biosorption of three heavy metal ions, copper(Ⅱ), zinc(Ⅱ), and chromimum(Ⅱ), from aqueous solution in the concentration range of 10\_100 mg/L was studied by using both entrapped activated sludge and inactivated free biomass at pH≤5. A biphasic metal adsorption pattern was observed in all immobilized biomass experiments. The biosorption of metal ions by the biosorbents increased with the initial concentration increased in the medium. The adsorption rate of immobilized pre-treated activated sludge(PAS) was much lower than that of free PAS due to the increase in mass transfer resistance resulting from the polymeric matrix. Biosorption equilibrium of beads was established in about 20 h and the adsorbed heavy metal ions did not change further with time. No significant effect of temperature was observed in the test for free biomass while immobilized PAS appeared to be strong temperature dependent in the test range of 10 and 40℃. Besides, the content of activated sludge in the calcium alginate bead has an influence on the uptake of heavy metals. The sorption equilibrium was well modeled by Langmuir isotherm, implying monomolecular adsorption mechanism. Carboxyl group in cell wall played an important role in surface adsorption of heavy metal ions on PAS.展开更多
Lead （Pb） chemical fixation is an important environmental aspect for human health. Phosphate rocks （PRs） were utilized as an adsorbent to remove Pb from aqueous solution. Raw PRs and oxalic acid-activated PRs （A...Lead （Pb） chemical fixation is an important environmental aspect for human health. Phosphate rocks （PRs） were utilized as an adsorbent to remove Pb from aqueous solution. Raw PRs and oxalic acid-activated PRs （APRs） were used to investigate the effect of chemical modification on the Pb-binding capacity in the pH range 2.0-5.0. The Pb adsorption rate of all treatments above pH 3.0 reached 90%. The Pb binding on PRs and APRs was pH-independent, except at pH 2.0 in activated treatments. The X-ray diffraction analysis confirmed that the raw PRs formed cerussite after reacting with the Pb solution, whereas the APRs formed pyromorphite. The Fourier Transform Infrared spectroscopy analysis indicated that carbonate （CO32-） in raw PRs and phosphate （PO43-） groups in APRs played an important role in the Pb-binding process. After adsorption, anomalous block-shaped particles were observed by scanning electron microscopy with energy dispersive spectroscopy. The X-ray photoelectron spectroscopy data further indicated that both chemical and physical reactions occurred during the adsorption process according to the binding energy. Because of lower solubility of pyromorphite compared to cerussite, the APRs are more effective in immobilizing Pb than that of PRs.展开更多
基金Supported by the National Natural Science Foundation of China(21036005)Scientific Technology Program of Zhejiang Province(2011C33016)
文摘Mycelia pellet formed spontaneously in the process of cultivation was exploited as a biological carrier for whole-cell immobilization due to its unique structural characteristic. An innovative two-species whole-cell im- mobilization system was achieved by inoculating the marine-derived fungus Pestalotiopsis sp. J63 spores into cul- ture medium containing another fungus Penicillium janthinellum P1 pre-grown mycelia pellets for 2 days without any pretreatment. In order to evaluate the biological degradation capacity of this novel constructed immobilization system, the immobilized pellets were applied to treat paper mill effluent and decolorize dye Azure B. The use of the constructed immobilization system in the effluent resulted in successful and rapid biodegradation of numerous in- soluble fine fibers. The optimum conditions of immobilized procedure for maximum biodegradation capacity were determined using orthogonal design with biomass of P1 pellets 10 g （wet mass）, concentration of J63 spore 2x109 mlq, and immobilization time 2 d. The results demonstrate that immobilized pellets have more than 99% biodegradation capacity in a ten-hour treatment process. The kinetics of biodegradation fits the Michaelis-Menten equation well. Besides, the decolorization capability of immobilized pellets is more superior than that of P1 mycelia pellets. Overall, the present study offers a simple and reproducible way to construct a two-species whole-cell immobiliza- tion system for sewage treatment.
基金supported by the National Natural Science Foundation of China(Nos.51873014,51521062,and 51473015).
文摘Converting renewable cellulose into glucose via cellulase catalysis for further production of biofuel has been recognized as one of the most promising ways for solving energy crisis.However,the hydrolysis performance of immobilized cellulase was not satisfactory for practical application due to the reduced catalytic efficiency and lack of β-glucosidase(BG)component in cellulase.Here,a facile method was developed to sequentially co-immobilize BG and cellulase by polymeric microparticles with hierarchical structure.In this strategy,BG was firstly entrapped into the cross-linked poly(ethylene glycol)(PEG)microparticles via inverse emulsion polymerization initiated by isopropyl thioxanthone(ITX)under the irradiation of visible light,leaving the formed ITX semi-pinacol(ITXSP)dormant groups on surface of BG-loaded microparticles,which could be further activated by visible light irradiation and initiated a graft polymerization to introduce poly(acrylic acid)(PAA)brush on the PEG core.After that,cellulase was covalently bonded on the PAA chains via carbodiimide reaction.The synergic effect of BG and cellulase was verified in the dual enzyme immobilization system,which led to a better stability at a wide range of temperature and pH than free enzymes.The dual enzymes system exhibited excellent reusability,which could retain 75%and 57%of the initial activity after 10 cycles of hydrolysis of carboxyl methyl cellulose and 5 cycles of hydrolysis of filter paper,respectively,indicative of the potential in biofuel areas in a cost-effective manner.
基金supported by the Capacity Building Project of Local University of Shanghai Municipal Science and Technology Commission(No.10230502900)the Program for Shanghai Collaborative Innovation Center for Cultivating Elite Breeds and Green-culture of Aquaculture animals(No.2021-KJ-02-12)the Innovation Project for Chongming Agriculture Industry from Chongming District Agriculture Commission of Shanghai(No.2022CNKC-01-05)。
文摘The efficiency and mechanism of hydrous iron oxide(HFO)and HFO/calcite mixture to inactivate the phosphorus in the overlying water(OW)/sediment system under the feed adding condition were explored,and the effect of HFO and HFO/calcite mixture addition on the diversity,composition and function of bacterial communities in the sediment was examined.HFO and HFO/calcite mixture direct addition can effectively lower the concentration of soluble reactive phosphorus(RSP)and diffusion gradient in thin film-unstable phosphorus(PD GT)in OW and inactivate the P DGTin the upper sediment.The elimination efficiencies of RSP by the direct HFO and HFO/calcite mixture addition were 48.9%-97.0%and 42.4%-95.4%,respectively.The alteration in the addition mode from the one-time to multiple direct addition was beneficial to the immobilization of RSP and PD GTin OW and P DGTin the upper sediment by HFO and HFO/calcite mixture under the feed input condition in the long run.Permeable fabric wrapping reduced the inactivation efficiency of RSP in OW by HFO and HFO/calcite mixture,but it made the recycling of these materials possible.Most of P immobilized by HFO and HFO/calcite mixture was relatively or very stable.After the HFO and HFO/calcite mixture addition,the composition of bacterial communities in the surface sediment changed.However,the bacterial communities in the amended sediments still can perform good ecological function.Our findings suggest that HFO and HFO/calcite mixture are promising phosphorus-immobilization materials for the inactivation of RSP and PD GTin OW and PD GTin the upper sediment under the feed inputting condition.
基金Supported by Chongqing Key Technologies R&D Program(CSTC2011AC101)Technology Supporting Program in 2013 of Chongqing Agriculture Committee~~
文摘[Objective] The aim was to seek effective soil remediation technologies suitable for soils slightly or moderately polluted. [Method] In-situ leaching-immobi- lization was used to research remediation soil and vegetable contaminated by lead in vegetable bases in Chongqing. [Result] By tartaric acid-based leaching-sodium sulphide-based immobilization, vegetable Pb reduction rate was 46.4%, soil Pb reduction rate was 8.45% and Pb immobilization rate was 9.3% in deeper horizons. EDTA leaching did reduce lead content in vegetables, but reduced vegetable yield simultaneously. [Conclusion] The coupling remediation technology brought heavy metal contents down in vegetables without affecting productions. Therefore, it guarantees vegetable safety and reduces vegetable farmer＇s economic loss. It is a remediation technology suitable for soils slightly or moderately contaminated by heavy metals.
基金Supported by Guangxi Provincial Natural Science Foundation ( 2011GXNSFA018080)General Science Research Program of Educational Commission of Guangxi Province of China [( 2009) No. 25]Phase Ⅱ of the Program for the Construction of Guangxi Key Laboratory of Environmental Engineering and Protection and Assessment
文摘[Objective] The aim was to study the immobilization of laccase from Canoderma lucidum in three different sol-gel systems to find out the optimum ma- terials for laccase immobilization. [ Method ] Laccase from G. lucidum LYL 263 was immobilized in sodium alginate-gelatin, sodium alginate-chitosan and sodium alginate-gelatin-chitosan sol-gel systems, respectively; and the laccase activity was preliminarily analyzed. [ Result] The activity of laccase immobilized in sodium alginate-gelatin-chitosan was 2.14 folds and 2.75 folds respectively, compared to sodium alginate-gelatin and sodium alginate-chitosan; and this optimum system contained sodium alginate 2.0% , gelatin 1.0%, chitosan 0.3% and calcium chloride 56%. Benzoic acid was firstly used to embed immobilized laccase in this study, and single-factor experiments revealed that the activity of laccase could be effectively improved by suitable content of benzoic acid. The optimal conditions for laccase immobilization in the system were be^oie acid 2 retool/L, glutaraldehyde 0.32%, cross-linking reaction time 50 rain and enzyme concentration 10.0% ; and then the activity of the immobilized enzyme reached 635.7 U/g with these conditions. The thermal stability of the immobilized laccase was higher than free lac- case, and the activity of immobilized enzyme treated by freeze-drying was 1.59 folds compared to the non-freeze-dried, but the freeze-dried immobilized laccase had poor operational stability. [ Conclusion] The compositions of the material had significant influence on laccase immobilization and this study will provide reference to select materials for immobilization of laccase from G. lacidum LYL 263.
基金supported by the Young Elite Scientists Sponsorship Program by Tianjin (No.TJSQNTJ-2020-16)Tianjin Science and Technology Program (No.19ZXSZSN00080)。
文摘Chromium is an important resource in strategic metals.Different from most studies focusing on the bio-reduction of hexavalent chromium[Cr(VI)],this study aims to achieve the immobilization and recovery of chromium using a sequencing batch biofilm reactor.Results showed that Cr(VI) removal efficiency remained more than 99%,and 97%of reduced Cr(III) was immobilized in the biofilm.Immobilization zone,chromium forms and extracellular polymeric substances composition changes were combined to reveal the mechanism of Cr(VI) reduction and immobilization.The chromium distribution in biofilm demonstrated that intercellular layer was the main active zone with an immobilization amount of 891.70±126.32 mg/g-VSS.The reduced products analysis confirmed that trivalent chromium[Cr(III)]chelated with carboxyl,amino and other functional groups and immobilized in the form of organic Cr(III).The digestion method realized a chromium recovery efficiency of 74.59%.This study provides an alternative method for the bioremediation and resources recovery in chromium polluted wastewater.
文摘Objective: To evaluate the effectiveness of a patient-specific immobilization and positioning device in prostate radiotherapy. Methods: Eighty patients were immobilized and positioned by a patient-specific device. Prostate translations and rotations were estimated from daily cone beam computed tomography scans using a contour-based approach assisted by auto-registration and quantified by the group mean GM, systematic Σ and random σ' errors. Dosimetric impacts of residual prostate rotations where the translation errors were corrected were evaluated by robustness plan analysis. Results: Using the patient-specific immobilization alone without online image-guidance, the GM, Σ and σ' of the prostate translations were 0.8, 1.7, and 1.5 mm (left-right;LR), 0.8, 2.1, and 1.9 mm (superior-inferior;SI), and 0.5, 1.7 and 1.5 mm (anterior-posterior;AP), while for the prostate rotations they were 0.0°, 0.6°, and 0.7°(pitch), 0.2°, 0.5°, and 0.6°(roll), and 0.2°, 0.5°, and 0.6°(yaw). The resulting van Herk’s margin was 5.8 (LR), 7.3 (SI) and 5.8 (AP) mm. With adaptive online image-guidance based on estimates from the first 5 fractions, Σ were reduced by 0.7 - 1.2 mm for the prostate translations, resulting in a margin reduction by 2 - 3.5 mm. Changes of Σ and σ' in the prostate rotations were insignificant regardless of translation corrections. Dosimetric impacts of residual rotation errors were negligible if a 2 mm margin was applied. Conclusions: Our patient-specific immobilization system can effectively limit the prostate translations and rotations, which is important without 6D treatment couches or using ultrasound image-guidance without rotational corrections.
基金supported by the National Key Research and Development Program of China(No.2020YFC1808701).
文摘Arsenic(As)pollution in soils is a pervasive environmental issue.Biochar immobilization offers a promising solution for addressing soil As contamination.The efficiency of biochar in immobilizing As in soils primarily hinges on the characteristics of both the soil and the biochar.However,the influence of a specific property on As immobilization varies among different studies,and the development and application of arsenic passivation materials based on biochar often rely on empirical knowledge.To enhance immobilization efficiency and reduce labor and time costs,a machine learning(ML)model was employed to predict As immobilization efficiency before biochar application.In this study,we collected a dataset comprising 182 data points on As immobilization efficiency from 17 publications to construct three ML models.The results demonstrated that the random forest(RF)model outperformed gradient boost regression tree and support vector regression models in predictive performance.Relative importance analysis and partial dependence plots based on the RF model were conducted to identify the most crucial factors influencing As immobilization.These findings highlighted the significant roles of biochar application time and biochar pH in As immobilization efficiency in soils.Furthermore,the study revealed that Fe-modified biochar exhibited a substantial improvement in As immobilization.These insights can facilitate targeted biochar property design and optimization of biochar application conditions to enhance As immobilization efficiency.
基金supported by the National Natural Science Foundation of China(Nos.41830753,42277201,42377242,and 41977286)the Scientific Research Foundation of Guangzhou University(No.YJ2023027)the College Student Innovation and Entrepreneurship Training Program(No.S202311078057).
文摘Arsenic-contaminated groundwater is widely used in agriculture.To meet the increasing demand for safe water in agriculture,an efficient and cost-effective method for As removal from groundwater is urgently needed.We hypothesized that Fe(oxyhydr)oxide(FeOOH)minerals precipitated in situ from indigenous Fe in groundwater may immobilize As,providing a solution for safely using As-contaminated groundwater in irrigation.To confirm this hypothesis and identify the controlling mechanisms,we comprehensively evaluated the transport,speciation changes,and immobilization of As and Fe in agricultural canals irrigated using As-contaminated groundwater.The efficiently removed As and Fe in the canals accumulated in shallow sediment rather than subsurface sediment.Linear combination fitting(LCF)analysis of X-ray absorption near edge spectroscopy(XANES)indicated that As(Ⅴ)was the dominant As species,followed by As(Ⅲ),and therewas no FeAsO_(4) precipitate.Sequential extraction revealed higher contents of amorphous FeOOH and associated As in shallower sediment than in the subsurface layer.Stoichiometric molar ratio calculations,SEM-EDS,FTIR,and fluorescence spectroscopy collectively demonstrated that the microbial reductive dissolution of amorphous FeOOH proceeded via reactive dissolved organic matter(DOM)consumption in subsurface anoxic porewater environment facilitating high labile As,whereas in surface sediment,the in situ-generated amorphous FeOOH was stable and strongly inhibited As release via adsorption.In summary,groundwater Fe^(2+)can efficiently precipitate in benthic surface sediment as abundant amorphous FeOOH,which immobilizes most of the dissolved As,protecting agricultural soil from contamination.This field research supports the critical roles of the phase and reactivity of in situ-generated FeOOH in As immobilization and provides new insight into the sustainable use of contaminated water.
基金supported d by the National Key Research and Development Program of China(No.2018YFC1802905).
文摘Two strains of Fe/Mn oxidizing bacteria tolerant to high concentrations of multiple heavy metal(loid)s and efficient decontamination for them were screened.The surface of the bio-Fe/Mn oxides produced by the oxidation of Fe(II)and Mn(II)by Pseudomonas taiwanensis(marked as P4)and Pseudomonas plecoglossicida(marked as G1)contains rich reactive oxygen functional groups,which play critical roles in the removal efficiency and immobilization of heavymetal(loid)s in co-contamination system.The isolated strains P4 and G1 can growwell in the following environments:pH 5-9,NaCl 0-4%,and temperature 20-30℃.The removal efficiencies of Fe,Pb,As,Zn,Cd,Cu,and Mn are effective after inoculation of the strains P4 and G1 in the simulated water system(the initial concentrations of heavy metal(loid)were 1 mg/L),approximately reaching 96%,92%,85%,67%,70%,54%and 15%,respectively.The exchangeable and carbonate bound As,Cd,Pb and Cu are more inclined to convert to the Fe-Mn oxide bound fractions in P4 and G1 treated soil,thereby reducing the phytoavailability and bioaccessible of heavy metal(loid)s.This research provides alternatives method to treat water and soil containing high concentrations of multi-heavy metal(loid)s.
基金supported by the National Natural Science Foundation of China(No.22076113)Shaanxi Province Key R&D Program Project(No.2020NY-235)。
文摘Coking wastewater,characterized by high biological toxicity,poses significant challenges for traditional biological treatment methods.This study developed a novel in-situ immobilized photocatalytic-algae-bacteria consortia(P-ABC)system using a polyether polyurethane sponge as a carrier,aiming to enhance biological treatment efficiency for actual coking wastewater.Results showed a 16.8%increase in algal density(up to 1.51×10^(5) cells/mL)in the P-ABC system compared to non-coupled controls,with significantly improved microbial metabolic activity,confirming the carrier's exceptional biocompatibility.Compared to standalone algae-bacteria consortia systems,the P-ABC system achieved higher removal efficiencies for chemical oxygen demand(COD_(Cr),19.8%),total organic carbon(TOC,21.2%),and total nitrogen(TN,30.4%).These findings validate the system's potential for improving stable and efficient treatment of industrial wastewater.Furthermore,this study offers insights into bio-enhanced treatment technologies and provides a reference pathway for integrating advanced oxidation and biological processes.
基金a funded project under the 2024 Hibah Penelitian Produktivitas Guru Besar(Professor Research Productivity Grant)scheme at Jember University.
文摘This study demonstrates the valorization of macadamia nutshells,a lignocellulosic agricultural waste,as both a carbon source for amylase production and a support matrix for enzyme immobilization.Under optimized solid-state fermentation conditions,Aspergillus niger ICP2 synthesized amylase with a peak activity of 0.312 U/mL after 72 hours.A four-step purification process of the crude enzyme extract resulted in a 188.54-fold increase in specific activity,albeit with a final recovery yield of 0.0031%.In parallel,nutshells were carbonized at 600℃,700℃,and 800℃,then chemically activated with ZnCl_(2).The carbon derived at 700℃ exhibited superior physicochemical characteristics,including enhanced porosity and increased availability of functional groups,which enabled effective enzyme adsorption,improved catalytic performance,and enhanced reusability.Immobilized amylase on this support retained approximately 30% of its initial activity after five hydrolysis cycles,demonstrating moderate operational reusability and potential for repeated use in bioprocesses.In contrast,carbon materials from 600℃ and 800℃ showed lower stability and enzyme performance.These findings highlight the critical role of carbonization conditions in designing effective immobilization matrices and underscore the potential of macadamia nutshells as a renewable and sustainable resource for biocatalyst development.This“biowaste-to-biocatalyst”strategy exemplifies a circular bioeconomy model with implications for green chemistry,industrial biocatalysis,and environmental sustainability.
基金supported by Beijing Municipal Commission of Education(No.Z161100004516015)the Open Project Program of Hebei Center for Ecological and Environmental Geology Research(No.JSYF-202304).
文摘As an energy and carbon saving process for nitrogen removal from wastewater,the partial nitrification and denitrification process(PN/D)has been extensively researched.However,achieving stable PNinmunicipalwastewater has always been challenging.In this study,a gel immobilized PN/D nitrogen removal process(GI-PN/D)was established.A 94 days pilot-scale experiment was conducted using real municipal wastewater with an ammonia concentration of 43.5±5.3mg N/L at a temperature range of 11.3–28.7◦C.The nitrogen removal performance and associated pathways,shifts in the microbial community as well as sludge yield were investigated.The results were as follows:the effluent TN and COD were 0.6±0.4mg/L and 31.1±3.8 mg/L respectively,and the NAR exceeding 95%.GI-PN/D achieved deep nitrogen removal ofmunicipalwastewater through stable PN without taking any othermeasures.The primary pathways for nitrogen removal were identified as denitrification,simultaneous nitrification-denitrification,and aerobic denitrification.High-throughput sequencing analysis revealed that the immobilized fillers facilitated the autonomous enrichment of functional bacteria in each reactor,effectively promoting the dominance and stability of the microbial communities.In addition,GI-PN/D had the characteristic of low sludge yield,with an average sludge yield of 0.029 kg SS/kg COD.This study provides an effective technical for nitrogen removal from municipal wastewater through PN.
基金supported by the Sichuan Outstanding Young Scientific and Technological Talents Project(No.2021JDJQ0016)Doctoral Initiation Project of China West Normal University(No.22k E043)and Science and Technology Project of Sichuan Province(No.2022NSFSC0388)。
文摘With the rapid development of nuclear energy,the removal of radioactive iodine generated during spent fuel reprocessing has become increasingly important.Based on the unique straw-like structure of populus tomentosa fiber(PTF)and the highly active iodine vapor capture ability of zero-valent silver nanoparticles(PTF@Ag^(0)NP),an Ag^(0)NP composite functional material with highly efficient iodine vapor capture capability was synthesized from biowaste PTF through ultrasonic and hightemperature hydrothermal methods in this study.The iodine capture experiment demonstrated that PTF@Ag^(0)NP exhibits rapid iodine capture efficiency,reaching dynamic equilibrium within 4 h and a maximum capture capacity of 1008.1 mg/g.Density functional theory calculations show that PTF@Ag^(0)NP exhibits extremely high chemical reactivity toward iodine,with a reaction binding energy of-2.88 e V.Additionally,the molecular dynamics of PTF@Ag^(0)NP indicate that there is no atomic displacement at 77?C,indicating the excellent temperature stability of the material at the operating temperature.The capture mechanism suggests that iodine vapor primarily reacts with Ag^(0)NP to form Ag I,and that the hydroxyl groups in PTF can also effectively capture iodine vapor by adsorption induction.In conclusion,PTF@Ag^(0)NP is expected to be an effective candidate adsorbent material for removing radioactive iodine vapor from exhaust gases during spent fuel reprocessing.
基金supported by the National Key R&D Program of China(2024YFA1211004)the National Natural Science Foundation of China(52300069,52192681,U21A20160)+1 种基金the Natural Science Foundation of Jiangsu Province(BK20230276)Science and Technology Program of Suzhou,China(SWY20222003,2022SS19).
文摘In photocatalytic water treatment processes,the particulate photocatalysts are typically immobilized on membrane,through either chemical/physical loading onto the surface or directly embedding in the membrane matrix.However,these immobilization strategies inevitably compromise the interfacial mass diffusion and cause activity decline relative to the suspended catalyst.Here,we propose a binder-free surface immobilization strategy for fabrication of high-activity photocatalytic membrane.Through a simple dimethylformamide(DMF)treatment,the nanofibers of polyvinylidene fluoride membrane were softened and stretched,creating enlarged micropores to efficiently capture the photocatalyst.Subsequently,the nanofibers underwent shrinking during DMF evaporation,thus firmly strapping the photocatalyst microparticles on the membrane surface.This surface self-bounded photocatalytic membrane,with firmly bounded yet highly exposed photocatalyst,exhibited 4.2-fold higher efficiency in hydrogen peroxide(H_(2)O_(2))photosynthesis than the matrix-embedded control,due to improved O_(2)accessibility and H_(2)O_(2)diffusion.It even outperformed the suspension photocatalytic system attributed to alleviated H_(2)O_(2)decomposition at the hydrophobic surface.When adopted for UV-based water treatment,the photocatalytic system exhibited tenfold faster micropollutants photodegradation than the catalyst-free control and demonstrated superior robustness for treating contaminated tap water,lake water and secondary wastewater effluent.This immobilization strategy can also be extended to the fabrication of other photocatalytic membranes with diverse catalyst types and membrane substrate.Overall,our work opens a facile avenue for fabrication of high-performance photocatalytic membranes,which may benefit advanced oxidation water purification application and beyond.
基金supported by the National Key Research and Development Program of China(Nos.2022YFC3703700 and 2021YFA0910300)the National Natural Science Foundation of China(No.22125606)the Special Project of Ecological Environmental Technology for Carbon Dioxide Emissions Peak and Carbon Neutrality(No.RCEES-TDZ-2021-21).
文摘Endocrine disruptors such as bisphenol A(BPA)adversely affect the environment and human health.Laccases are used for the efficient biodegradation of various persistent organic pollutants in an environmentally safe manner.However,the direct application of free laccases is generally hindered by short enzyme lifetimes,non-reusability,and the high cost of a single use.In this study,laccases were immobilized on a novel magnetic threedimensional poly(ethylene glycol)diacrylate(PEGDA)-chitosan(CS)inverse opal hydrogel(LAC@MPEGDA@CS@IOH).The immobilized laccase showed significant improvement in the BPA degradation performance and superior storage stability compared with the free laccase.91.1%of 100 mg/L BPA was removed by the LAC@MPEGDA@CS@IOH in 3 hr,whereas only 50.6%of BPA was removed by the same amount of the free laccase.Compared with the laccase,the outstanding BPA degradation efficiency of the LAC@MPEGDA@CS@IOH was maintained over a wider range of pH values and temperatures.Moreover,its relative activity of was maintained at 70.4%after 10 cycles,and the system performed well in actual water matrices.This efficientmethod for preparing immobilized laccases is simple and green,and it can be used to further develop ecofriendly biocatalysts to remove organic pollutants from wastewater.
基金Project(2023YFC3207000)supported by the National Key Research and Development Program of ChinaProject(2024RC1008)supported by the Science&Technology Innovation Program of Hunan Province,China。
文摘Arsenic(As)contamination of groundwater is a serious global issue requiring effective and sustainable remediation strategies.For long-term As immobilization,this study explores the potential of in-situ magnetite precipitation,induced by anaerobic nitrate-reducing Fe(II)-oxidizing(NRFO)bacteria.A nitrate-intercalated layered double hydroxide(NO_(3)^(-)MgFe LDH)was introduced to provide nitrate as an electron acceptor for Fe(II)bio-oxidation and serve as an iron-based precursor in magnetite formation.The experimental results showed that NO_(3)^(-)MgFe LDH was transformed into green rust(GR)in the presence of Fe(II)and HCO_(3)^(-).Meanwhile,0.5 g/L of NO_(3)^(-)MgFe LDH released cumulatively about 1.21 mM of nitrate within 12 h,promoting the transformation of GR into magnetite induced by Acidovorax sp.BoFeN1.As a result,the aqueous As concentration decreased from 2 mg/L to<0.008 mg/L,with approximately 70%of As confined in recalcitrant Fe oxides,suggesting high potential for long-term As immobilization.Environmental factors influenced the transformation process:a lower Fe(II)concentration(0.5 mM)delayed GR formation,while varying HCO_(3)^(-)concentrations(2.5-10 mM)had minimal effect.Subsequently,an elevated As level(5 mg/L)inhibited the bio-formation of magnetite,leading to lepidocrocite as the dominant mineral phase.Given the stability of magnetite,this study provides a cost-effective and environmentally friendly strategy for the durable in-situ remediation of As-contaminated groundwater.
基金Project supported by the National Natural Science Foundation of China(No.50327802,50325824,50678089).
文摘The microbial immobilization method using polyvinyl alcohol （PVA） gel as an immobilizing material was improved and used for entrapment of activated sludge. The oxygen uptake rate （OUR） was used to characterize the biological activity of immobilized activated sludge. Three kinds of PVA-immobilized particles of activated sludge, that is, PVA-boric acid beads, PVA-sodium nitrate beads and PVA-orthophosphate beads were prepared, and their biological activity was compared by measuring the OUR value. The bioactivity of both autotrophic and heterotrophic microorganisms of activated sludge was determined using different synthetic wastewater media （containing 250 mg/L COD and 25 mg/L NH4^＋ -N）. The experimental results showed that the bioactivity and stability of the three kinds of immobilized activated sludge was greatly improved after activation. With respect of the bioactivity and the mechanical stability, the PVA-orthophosphate method may be a promising and economical technique for microbial immobilization.
文摘Activated sludge was immobilized into Ca-alginate beads via entrapment, and biosorption of three heavy metal ions, copper(Ⅱ), zinc(Ⅱ), and chromimum(Ⅱ), from aqueous solution in the concentration range of 10\_100 mg/L was studied by using both entrapped activated sludge and inactivated free biomass at pH≤5. A biphasic metal adsorption pattern was observed in all immobilized biomass experiments. The biosorption of metal ions by the biosorbents increased with the initial concentration increased in the medium. The adsorption rate of immobilized pre-treated activated sludge(PAS) was much lower than that of free PAS due to the increase in mass transfer resistance resulting from the polymeric matrix. Biosorption equilibrium of beads was established in about 20 h and the adsorbed heavy metal ions did not change further with time. No significant effect of temperature was observed in the test for free biomass while immobilized PAS appeared to be strong temperature dependent in the test range of 10 and 40℃. Besides, the content of activated sludge in the calcium alginate bead has an influence on the uptake of heavy metals. The sorption equilibrium was well modeled by Langmuir isotherm, implying monomolecular adsorption mechanism. Carboxyl group in cell wall played an important role in surface adsorption of heavy metal ions on PAS.
基金supported by the National Natural Science Foundation of China (No. 41071165)the Special Research Fund for the Doctoral Program of Higher Education, Ministry of Education (No. 20090146110003)
文摘Lead （Pb） chemical fixation is an important environmental aspect for human health. Phosphate rocks （PRs） were utilized as an adsorbent to remove Pb from aqueous solution. Raw PRs and oxalic acid-activated PRs （APRs） were used to investigate the effect of chemical modification on the Pb-binding capacity in the pH range 2.0-5.0. The Pb adsorption rate of all treatments above pH 3.0 reached 90%. The Pb binding on PRs and APRs was pH-independent, except at pH 2.0 in activated treatments. The X-ray diffraction analysis confirmed that the raw PRs formed cerussite after reacting with the Pb solution, whereas the APRs formed pyromorphite. The Fourier Transform Infrared spectroscopy analysis indicated that carbonate （CO32-） in raw PRs and phosphate （PO43-） groups in APRs played an important role in the Pb-binding process. After adsorption, anomalous block-shaped particles were observed by scanning electron microscopy with energy dispersive spectroscopy. The X-ray photoelectron spectroscopy data further indicated that both chemical and physical reactions occurred during the adsorption process according to the binding energy. Because of lower solubility of pyromorphite compared to cerussite, the APRs are more effective in immobilizing Pb than that of PRs.
