The basic chemistry laboratories of three colleges and universities in Guizhou Province were investigated completely,especially the pollution situations of the basic chemistry projects were counted,and the discharge a...The basic chemistry laboratories of three colleges and universities in Guizhou Province were investigated completely,especially the pollution situations of the basic chemistry projects were counted,and the discharge amounts of the poisonous and harmful pollutants in the waste liquid from laboratories were monitored and analyzed.On the basis of the summing-up and analysis of the current research findings,a simple and feasible treatment scheme through flocculating,precipitating and constructed wetlands was designed to control the three kinds of excessive pollutants.展开更多
Inexpensive flocculant-modified iron tailings sand(ITS)were converted into effective flocculation materials for cyanobacteria blooms.After composite modification with polyaluminum chloride(PAC)and polyacrylamide(PAM),...Inexpensive flocculant-modified iron tailings sand(ITS)were converted into effective flocculation materials for cyanobacteria blooms.After composite modification with polyaluminum chloride(PAC)and polyacrylamide(PAM),the surface charge of ITS was altered from negative to positive,and surface adhesion was increased by~1.5 times.PAC/PAM-modified ITS(PP-ITS)had strong flocculating effects on cyanobacteria,facilitating their removal.When the dosage of PP-ITS was 150 mg/L and the ratio of flocculant to ITS was 1:20,the elimination rate of cyanobacteria was as high as 90%.The flocs formed were better than those with chitosan-modified clays(CS-CA)and PAC-modified ITS(PAC-ITS)in terms of settling velocity,size,and recovery ability.The positively charged groups in the flocculant,such as-NH_(2) and Al^(3+),are attracted to negatively charged ions on the surface of ITS,altering the surface charge.Additionally,hydrogen bonds could form between amide side groups,and surface adhesion was improved through molecular association.Coupled with the strong bridging and sweeping effects of the flocculant,the flocs generated by PP-ITS formed rapidly and were large and resilient.The use of PP-ITS could effectively treat cyanobacteria blooms as well as solve the problem of ore tailings disposal.These results are of practical importance for engineering strategies to control cyanobacteria blooms,though there are still some issues that need to be addressed,such as how cyanobacteria flocs are collected and utilized after settling.展开更多
The valorization of plant biomass towards high-value chemicals is a global trend aimed at solving the problem of the huge accumulation of lignocellulosic waste.Plant polysaccharides are natural polymers that make up a...The valorization of plant biomass towards high-value chemicals is a global trend aimed at solving the problem of the huge accumulation of lignocellulosic waste.Plant polysaccharides are natural polymers that make up about 20%by weight of biomass,with a unique variety of structures and properties that depend on the type of raw materials and themethod of their extraction.In this study,the effect of variability of the oxidative delignification process conditions in the《acetic acid-hydrogen peroxide-water-(NH_(4))_(6)Mo_(7)O_(24)》on the extraction and properties of aspen(Populus tremula)wood hemicelluloses was investigated for the first time.The developed method for the extraction of hemicelluloses provided the production of water-soluble polysaccharides with a high yield(to 62.55 wt.%in relation to total content in wood),high purity,with a branched structure and active centers on the side chains in the form of uronic acids.In the course of the work,it was found that the obtained hemicelluloses aremainly represented by partially acetylated galactoxylan and glucuronoxylan.Promising results of biological studies of the antioxidant and flocculation activity of xylans are promising for the use of plant polysaccharides in health care and food industry.展开更多
The flocculation behavior of carbon black (CB)-filled isoprene rubber (IR) nanocomposites was systematically investigated under both dynamic and static conditions to unravel the distinct mechanisms governing filler ne...The flocculation behavior of carbon black (CB)-filled isoprene rubber (IR) nanocomposites was systematically investigated under both dynamic and static conditions to unravel the distinct mechanisms governing filler network evolution.Under dynamic conditions,small oscillatory shear strains (0.1%) significantly enhanced filler particle motion,leading to pronounced agglomeration and a flocculation degree of about 4.3MPa at 145℃.In contrast,static flocculation exhibited a fundamentally different mechanism dominated by polymer chain dynamics,which is driven mainly by thermal activation.Radial distribution function (RDF) analysis of transmission electron microscopy (TEM) images revealed a slight decrease (2 nm) in the interparticle distance peak after static annealing at 100℃ for 7 h,indicating localized motion of CB particles.However,the overall filler network remained stable,with no significant agglomeration observed.The increase in bound rubber content from about 23% to 28% with rising temperature further confirmed the dominant role of polymer chain adsorption and interfacial reinforcement in static flocculation.These findings highlight the critical influence of external strain on filler network formation and provide new insights into the polymer-dominated mechanism of static flocculation.The results offer practical guidance for optimizing the storage and processing of rubber nanocomposites,particularly in applications where static flocculation during prolonged storage is a concern.展开更多
Chalcopyrite is often intergrown with talc,which,after grinding,forms ultrafine particles(<10μm)that readily coat chalcopyrite surfaces,hindering flotation and causing significant losses in tailings.This study eva...Chalcopyrite is often intergrown with talc,which,after grinding,forms ultrafine particles(<10μm)that readily coat chalcopyrite surfaces,hindering flotation and causing significant losses in tailings.This study evaluates polyvinyl acetate(PVAc),a thermoplastic polymer,as a selective flocculant to enhance reverse flot ation separation of chalcopyrite from ultrafine talc.Flotation tests showed that at a PVAc dosage of 40 mg/L,talc can be effectively and selectively removed,enabling efficient separation.Laser particle size analysis and scanning electron microscopy-energy dispersive spectrometry(SEM-EDS)confirmed that PVAc promotes selective talc aggregation without affecting chalcopyrite.X-ray photoelectron spectroscopy(XPS)and density functional theory(DFT)calculations revealed that hydrogen bonding between PVAc ester groups and surface hydroxyls on talc drives the flocculation,while chalcopyrite lacks suitable binding sites.PVAc adsorption also enhances talc hydrophobicity.Furthermore,particle-bubble coverage angle measurements and extended Derjaguin-Landau-Verwey-Overbeek(DLVO)theory theoretical calculations demonstrated that PVAc-induced flocculation increases attractive interactions between talc and bubbles,shifting the total interaction energy from repulsive to attractive and promoting bubble-particle attachment.This study clarifies the selective adsorption and flocculation mechanisms of PVAc and reveals the coupling of flocculation and flotation of ultrafine talc from a particle-bubble capture perspective,while expanding the potential of ester-based polymers for ultrafine mineral recovery.展开更多
Hypersaline mariculture wastewater necessitates treatment prior to its discharge into marine environments.Algal-mycelial pellets(AMPs),known for their cost-effectiveness,energy efficiency and sustainability,have not b...Hypersaline mariculture wastewater necessitates treatment prior to its discharge into marine environments.Algal-mycelial pellets(AMPs),known for their cost-effectiveness,energy efficiency and sustainability,have not been previously explored for their flocculation and pollutant removal capabilities in hyperhaline conditions.This work employed an orthogonal test design to investigate the effects of nine factors at three levels on the treatment efficiency of mariculture wastewater using Chlorella sp.TNBR1 and Aspergillus niger AMPs.The comprehensive optimal conditions for achieving the highest flocculation efficiency and pollutant removal are determined to be a temperature of 30℃,light intensity of 6000 lux,a 12:0 light-dark cycle,an initial pH of 6,amicroalgal density of 11.25×10^(6)cell/mL,microalgal growth phase at the early logarithmic stage,a fungal spore density of 9.00×10^(5)spore/mL and a fungal pellet phase of 60 h.Under such conditions,the treatment of nonsterile actual mariculture wastewater with Chlorella sp.TNBR1 and Aspergillus niger AMPs results in a 93.35%±7.20%reduction in chemical oxygen demand(COD),92.83%±7.29%reduction in total nitrogen(TN),100%removal of total phosphorus(TP),and a flocculation efficiency of 69.21%±5.36%.These findings confirm that AMPs are a viable solution for effectively treating COD,TN and TP in real hypersaline mariculture wastewater,while also facilitating the flocculation and harvesting of microalgae.展开更多
Effects of stirring speed and time, pH and sodium oleate concentration on the shear hydrophobic flocculation of ultrafine Anshan hematite with sodium oleate as the surfactant were discussed. The results show that thes...Effects of stirring speed and time, pH and sodium oleate concentration on the shear hydrophobic flocculation of ultrafine Anshan hematite with sodium oleate as the surfactant were discussed. The results show that these parameters significantly affect the shear hydrophobic flocculation of ultrafine hematite. The optimum conditions for the flocculation are： stirring speed 1 400 r/min, flocculation time 20 min, pH 9 and sodium oleate concentration 3.94×10-4 mol/L; the flotation recovery of hematite flocs is remarkably high compared with non flocculated ultrafine hematite. According to the extended DLVO theory, the total interaction potential of Anshan ultrafine hematite was determined. The calculation results indicate that the hydrophobic flocculation state of the ultrafine hematite-sodium oleate system is mainly dominated by electric double layer repulsive interaction potential and hydrophobic interaction potential. A mechanical agitation is required to impart particles a kinetic energy to overcome potential barrier between them due to the existence of electric double layer repulsive interaction potential. Those particles further approach to form flocs due to the significant increase of the hydrophobic interaction potential.展开更多
In order to accelerate the sedimentation of super-large-scale argillized ultrafine tailings with bad features such as low settling velocity, muddy overflow water, and large flocculant dosage, a fly-ash-based magnetic ...In order to accelerate the sedimentation of super-large-scale argillized ultrafine tailings with bad features such as low settling velocity, muddy overflow water, and large flocculant dosage, a fly-ash-based magnetic coagulant （FAMC） was used in a dynamic experimental device. To obtain the best possible combination of the impact factors （magnetic intensity, FAMC dosage, flocculant dosage, and feed speed） for minimum overflow turbidity, a response surface methodology test coupled with a four-factor five-level central composite design was conducted. The synergy mechanism of FAMC and flocculant was analyzed based on the potential measurement and scanning electron microscopy. The results show that the flocculant dosage, overflow turbidity, and solid content can be reduced by 50%, 90%, and 80%, while the handling capacity per unit and efficiency of backfill and dry stacking can be promoted by 20%, 17%, and 13%, respectively, with a magnetic intensity of 0.3 T, FAMC dosage of 200 mL/t, flocculant dosage of 30 g/t, and feed speed of 0.6 t/（m^2·h）. Therefore, synergy of FAMC and flocculant has obvious efficiency in saving energy and protecting the environment by allowing 70×10^6 t/a of argillized ultrafine tailings slurry to be disposed safely and efficiently with a cost saving of more than 53×106 Yuan/a, which gives it great promise for use in domestic and foreign mines.展开更多
A novel inorganic polymer flocculant,poly-ferric sulfate（BPFS） was prepared by oxidation of ferrous sulfate using domestic Thiobacillus ferrooxidans（T·f） under acid condition.The optimal conditions for the pr...A novel inorganic polymer flocculant,poly-ferric sulfate（BPFS） was prepared by oxidation of ferrous sulfate using domestic Thiobacillus ferrooxidans（T·f） under acid condition.The optimal conditions for the preparation were pH value of 1.5,（NH4）2SO4 dosage of 0.5 g/L,initial Fe2＋ concentration of 45g/L,inoculum 10%,rotating speed of 120 r/min,reaction time of 5-6 d and reaction temperature of 30 ℃.Under the optimal conditions,the BPFS product with pH value of 1.5-2.2,basicity of 17.5%-22.7% and total iron content of 43.87-45.24 g/L was obtained.The application of the BPFS to three wastewaters was carried out,and the removal efficiencies of COD,decolorization and Zn2＋ by BPFS can be reached 70%,90% and 99%,respectively.The result suggests that the BPFS is an excellent flocculant for water treatment.展开更多
[Objective] To screen out a microbial flocculant with good decolorization effect on methyl orange wastewater,and study the effect of different cultural conditions on decolorization effect of methyl orange.[Method] Abs...[Objective] To screen out a microbial flocculant with good decolorization effect on methyl orange wastewater,and study the effect of different cultural conditions on decolorization effect of methyl orange.[Method] Absorbance of methyl orange solution before and after decolorization was determined by spectrophotometer,and the decolorization rate was calculated to compare the effects of different cultural conditions on removal rate of methyl orange.[Result]An optimal actinomycete stain（F-1-2） was screened out,and the best cultural condition was as follows：with sucrose as carbon source and NaNO3 as nitrogen source,cultured in constant temperature oscillator at 150 r/min,30℃ for 72 h.Under the optimal condition,the removal rate against methyl orange could reach 68.4%.[Conclusion]Different culture conditions have great impact on decolorization effect of strain.展开更多
[Objective] The aim was to indentify a bioflocculatnt producing strain W5 isolated from soil samples and analyze its flocculating characteristics. [Method] The universal primers of bacterial 16S rDNA were used for PCR...[Objective] The aim was to indentify a bioflocculatnt producing strain W5 isolated from soil samples and analyze its flocculating characteristics. [Method] The universal primers of bacterial 16S rDNA were used for PCR amplification of its genome; effects of the medium pH,carbon and nitrogen sources on its flocculating activity were analyzed by using single factor method; and infrared spectroscopy was used for functional groups analysis. [Result] The results of homology comparison showed that strain W5 belonging to Gram-negative,long bacilli and had 98.34% of homology with Hymenobacter gelipurpurascens,. In addition,the optimum carbon source,nitrogen source,pH for fermentation condition were glucose,yeast extract and pH 7.04,respectively. Microbe flocculant produced by W5 strain （MBF-W5） was extracted and purified to obtain reddish and flocculent products. Fourier-transform infrared （FTIR） spectroscopy indicated that the major functional groups of MBF-W5 were hydroxyl,carboxyl and amino. [Conclusion] More than 85% of flocculating activity was achieved under the conditions of 150-500 μl bioflocculation dosage,5-65 ℃ temperature and pH 2-10.展开更多
[Objective] This study aimed to screen a bacterial strain capable of producing bioflocculant. [Method] A bacterial strain T-11 capable of producing bioflocculant was isolated from activated sludge. Detailed tests on t...[Objective] This study aimed to screen a bacterial strain capable of producing bioflocculant. [Method] A bacterial strain T-11 capable of producing bioflocculant was isolated from activated sludge. Detailed tests on the morphological, physiological and biochemical characteristics were carried out and identification was performed to identify the strain. Finally, the bioflocculant was isolated and purified, and the flocculating activity and chemical characteristics were measured. [Result] It was identified as Serratia plumuthica based on its morphological, physiological and biochemical characteristics. This strain secreted flocculant best in a culture medium which included sucrose and NaNO3. The maximal cell growth was achieved within 10 h and the flocculating activity paralleled to it. It was found to be effective for flocculation of kaolin suspension, when added at a final concentration of 0.7 mg/L, over a range of pHs （2-7）, and temperature （approximately 30-80 ℃）. Chemical analysis indicated that the bioflocculant was an acidic polysaccharide consisting of glucose, glucuronic acid and galactose, talose and altrose. Infrared spectrum analysis also revealed typical characteristics of polysaccharides. [Conclusion] The biofloccu- lants produced by strain T-11 can greatly improve the ability of activated sludge to settle.展开更多
The effect of electrolyte on settling behavior of kaolinite was studied. Effects of hard water on selective flocculation of diasporic bauxite was tested and the measures were taken to eliminate the effects of Ca2＋ an...The effect of electrolyte on settling behavior of kaolinite was studied. Effects of hard water on selective flocculation of diasporic bauxite was tested and the measures were taken to eliminate the effects of Ca2＋ and Mg2＋ in hard water. The results indicated that, not only the concentration of electrolyte ions but also the ionic valence of the electrolyte ions affects the settling behavior of kaolinite; hard water significantly affects its selective flocculation owing to Ca2＋ and Mg2＋; general dispersants could not eliminate the effects of Ca2＋ and Mg2＋. Self-made softening agent in our lab could weaken or eliminate the effects of hard water on flocculation processes. The results of molecular dynamics simulation show that softening agent molecules could restrict Ca2＋ and prevent them from playing their roles, so as to eliminate the effects. The continuous pilot experiment results of bauxite flocculation were even better than those obtained in laboratory.展开更多
The composition of tailings particles in mines plays a key role in the flocculation settlement of slurries.To study the influence of coarse particle tailings(CPTs)on the flocculation settlement of tailings slurries(TS...The composition of tailings particles in mines plays a key role in the flocculation settlement of slurries.To study the influence of coarse particle tailings(CPTs)on the flocculation settlement of tailings slurries(TSs),static flocculent settling tests,scanning electron microscopy observations,and laser particle size analyses were conducted using the tailings obtained from a copper mine.The results demonstrate that(i)in the accelerated and free settling process,CPTs did not directly settle at the bottom of graduated cylinders;instead,they were netted by the flocculent structures(FSs)and settled together more quickly.The CPTs accelerate the rapid settlement of TSs;the acceleration effect is more obvious when the CPTs content is greater than 50 wt%.(ii)The most appropriate flocculant unit consumption(FUC)is 20 g·t-1,and no substantial increase is observed in the flocculant settling velocity with an increase in the flocculant because the effective FSs did not substantially change and thus did not lead to a notable increase in the settling velocity of the solid–liquid interface(SLI).(iii)In the effective settling space of the thickening facility,free water quickly flowed from the pores of FSs,which is reflected in the period from 0 to 1 min.展开更多
As a special biofilm structure,microbial attachment is believed to play an important role in the granulation of aerobic granular activated sludge（AGAS）.This experiment was to investigate the biological effect of Ca^...As a special biofilm structure,microbial attachment is believed to play an important role in the granulation of aerobic granular activated sludge（AGAS）.This experiment was to investigate the biological effect of Ca^2＋,Mg^2＋,Cu^2＋,Fe^2＋,Zn^2＋,and K＋which are the most common ions present in biological wastewater treatment systems,on the microbial attachment of AGAS and flocculent activated sludge（FAS）,from which AGAS is always derived,in order to provide a new strategy for the rapid cultivation and stability control of AGAS.The result showed that attachment biomass of AGAS was about 300%higher than that of FAS without the addition of metal ions.Different metal ions had different effects on the process of microbial attachment.FAS and AGAS reacted differently to the metal ions as well,and in fact,AGAS was more sensitive to the metal ions.Specifically,Ca^2＋,Mg^2＋,and K＋could increase the microbial attachment ability of both AGAS and FAS under appropriate concentrations,Cu^2＋,Fe^2＋,and Zn^2＋were also beneficial to the microbial attachment of FAS at low concentrations,but Cu^2＋,Fe^2＋,and Zn^2＋greatly inhibited the attachment process of AGAS even at extremely low concentrations.In addition,the acylated homoserine lactone（AHL）-based quorum sensing system,the content of extracellular polymeric substances and the relative hydrophobicity of the sludges were greatly influenced by metal ions.As all these parameters had close relationships with the microbial attachment process,the microbial attachment may be affected by changes of these parameters.展开更多
[Objective] The purpose was to select out and identify a flocculant producing strain which could produce high active flocculant.[Method] The strain producing high active flocculant was isolated out and purified throug...[Objective] The purpose was to select out and identify a flocculant producing strain which could produce high active flocculant.[Method] The strain producing high active flocculant was isolated out and purified through medium culture and the selected strain was identified through observing its culture characters and determining its physiological and biochemical property.[Result] Fourteen strains of bacteria with flocculant producing function were isolated from tested soil samples through isolation,purification and preliminary screening using dilution-spread plate method and plate streaking method.Five strains of flocculant producing bacteria showing higher flocculation activity were selected out after second screening and their flocculation rates were higher than 70%;the flocculation activity of one strain among them was still stable after multiple subculturings,its flocculation rate was always above 90% and it was marked as TS-1.TS-1 was encapsulated Gram-positive bacillus and there was no lipid in it,such as poly-β-hydroxybutyric acid.TS-1 was Bacillus amyloliquefaciens,so it was named Bacillus TS-1.[Conclusion] The strain selected out in this experiment could be used in the flocculation and biochemical treatment of wastewater from starch industry.展开更多
The hydrophobic flocculation of marmatite fines in aqueous suspensions induced by butyl xanthate （KBX） and ammonium dibutyl dithiophosphate （ADD） was investigated using laser particle size analysis, microscopy ana...The hydrophobic flocculation of marmatite fines in aqueous suspensions induced by butyl xanthate （KBX） and ammonium dibutyl dithiophosphate （ADD） was investigated using laser particle size analysis, microscopy analysis, electrophoretic light scattering, contact angle measurement and infrared spectroscopy. The studies were performed on single minerals with size 〈20 μm by varying several parameters, including pH, collector concentration and kerosene addition. The results show that the floc fotation closely correlated with the size of flocs and the particle hydrophobicity, but was not lowered with increasing the particle surface charges due to collector adsorption. Under good operating conditions, the floc flotation of marmatite fines as a function of KBX and ADD can all reach floatability over 90%, in comparison with conventional flotation obtaining floatability of about 60%. It also has been found that a small addition of kerosene greatly improved the floc flotation because of the formation of oil films on marmatite particles. The results of FTIR spectra indicate that adsorption of the two collectors onto marmatite were chemical adsorption.展开更多
[Objective] The technological parameter suitable for the dewatering of dredged sediment from Dianchi Lake was studied.[Method] By means of the treatment method of sewage sludge in sewage treatment plant,flocculants in...[Objective] The technological parameter suitable for the dewatering of dredged sediment from Dianchi Lake was studied.[Method] By means of the treatment method of sewage sludge in sewage treatment plant,flocculants including FeCl3,Al2(SO4)3 and PAM were taken as dewatering agents which were added in dredged sediment.[Result] The results showed that Al2(SO4)3 had better dewatering effect than FeCl3 and PAM,and the optimum dosing quantity of Al2(SO4)3 in dredged sediment was 170 mg/L,in addition,the water quality of supernatant met the first class B standard of GB18918-2002 and could be directly discharged to nature water without pollution.[Conclusion] The study could provide a simple and feasible way for the rapid dewatering of dredged sediment from Dianchi Lake,which would be convenient for the disposal and resource utilization of dredged sediment.展开更多
In this paper, the conditions of modified melamine formaldehyde resin (MF) used for a flocculent such as the ratio of reactant, reaction time, reaction temperature and the value of pH, were studied. The preferable syn...In this paper, the conditions of modified melamine formaldehyde resin (MF) used for a flocculent such as the ratio of reactant, reaction time, reaction temperature and the value of pH, were studied. The preferable synthetic conditions were melamine:formaldehyde:acrylamide (mole)=1:5:(2～3), reaction temperature 70 ℃, reaction time 4 h, pH 9.0.展开更多
A coagulation/flocculation process using the composite flocculant polyaluminum chloride-epichlorohydrin dimethylamine （PAC- EPI-DMA） was employed for the treatment of an anionic azo dye （Reactive Brilliant Red K-2B...A coagulation/flocculation process using the composite flocculant polyaluminum chloride-epichlorohydrin dimethylamine （PAC- EPI-DMA） was employed for the treatment of an anionic azo dye （Reactive Brilliant Red K-2BP dye）. The effect of viscosity 01）, basicity （B = [OH]/[Al]） and organic content （Wp） on the flocculation performance as well as the mechanism of PAC-EPI-DMA flocculant were investigated. The η was the key factor affecting the dye removal efficiency of PAC-EPI-DMA. PAC-EPI-DMA with an intermediate η （2400 mPa.sec） gave higher decolorization efficiency by adsorption bridging and charge neutralization due to the co-effect of PAC and EPI-DMA polymers. The Wp of the composite flocculant was a minor important factor for the flocculation. The adsorption bridging of PAC-EPI-DMA with η of 300 or 4300 mPa.sec played an important role with the increase of Wp, whereas the charge neutralization of them was weaker with the increase of Wp. There was interaction between Wp and B on the removal of reactive dye. The composite flocculant with intermediate viscosity and organic content was effective for the treatment of reactive dyeing wastewater, which could achieve high reactive dye removal efficiency with low organic dosage.展开更多
基金Supported by Natural Science Foundation Projects of Education Department of Guizhou Province (2006319)
文摘The basic chemistry laboratories of three colleges and universities in Guizhou Province were investigated completely,especially the pollution situations of the basic chemistry projects were counted,and the discharge amounts of the poisonous and harmful pollutants in the waste liquid from laboratories were monitored and analyzed.On the basis of the summing-up and analysis of the current research findings,a simple and feasible treatment scheme through flocculating,precipitating and constructed wetlands was designed to control the three kinds of excessive pollutants.
基金Supported by the National Key Research and Development Program of China(No.2022 YFC 3202700)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX 24_0904)。
文摘Inexpensive flocculant-modified iron tailings sand(ITS)were converted into effective flocculation materials for cyanobacteria blooms.After composite modification with polyaluminum chloride(PAC)and polyacrylamide(PAM),the surface charge of ITS was altered from negative to positive,and surface adhesion was increased by~1.5 times.PAC/PAM-modified ITS(PP-ITS)had strong flocculating effects on cyanobacteria,facilitating their removal.When the dosage of PP-ITS was 150 mg/L and the ratio of flocculant to ITS was 1:20,the elimination rate of cyanobacteria was as high as 90%.The flocs formed were better than those with chitosan-modified clays(CS-CA)and PAC-modified ITS(PAC-ITS)in terms of settling velocity,size,and recovery ability.The positively charged groups in the flocculant,such as-NH_(2) and Al^(3+),are attracted to negatively charged ions on the surface of ITS,altering the surface charge.Additionally,hydrogen bonds could form between amide side groups,and surface adhesion was improved through molecular association.Coupled with the strong bridging and sweeping effects of the flocculant,the flocs generated by PP-ITS formed rapidly and were large and resilient.The use of PP-ITS could effectively treat cyanobacteria blooms as well as solve the problem of ore tailings disposal.These results are of practical importance for engineering strategies to control cyanobacteria blooms,though there are still some issues that need to be addressed,such as how cyanobacteria flocs are collected and utilized after settling.
基金supported by the Russian Science Foundation,project no.22-73-10212,https://rscf.ru/en/project/22-73-10212/(accessed on 14 April 2025).
文摘The valorization of plant biomass towards high-value chemicals is a global trend aimed at solving the problem of the huge accumulation of lignocellulosic waste.Plant polysaccharides are natural polymers that make up about 20%by weight of biomass,with a unique variety of structures and properties that depend on the type of raw materials and themethod of their extraction.In this study,the effect of variability of the oxidative delignification process conditions in the《acetic acid-hydrogen peroxide-water-(NH_(4))_(6)Mo_(7)O_(24)》on the extraction and properties of aspen(Populus tremula)wood hemicelluloses was investigated for the first time.The developed method for the extraction of hemicelluloses provided the production of water-soluble polysaccharides with a high yield(to 62.55 wt.%in relation to total content in wood),high purity,with a branched structure and active centers on the side chains in the form of uronic acids.In the course of the work,it was found that the obtained hemicelluloses aremainly represented by partially acetylated galactoxylan and glucuronoxylan.Promising results of biological studies of the antioxidant and flocculation activity of xylans are promising for the use of plant polysaccharides in health care and food industry.
基金supported by the National Natural Science Foundation of China(No.52293471)National Key R&D Program of China(No.2022YFB3707303).
文摘The flocculation behavior of carbon black (CB)-filled isoprene rubber (IR) nanocomposites was systematically investigated under both dynamic and static conditions to unravel the distinct mechanisms governing filler network evolution.Under dynamic conditions,small oscillatory shear strains (0.1%) significantly enhanced filler particle motion,leading to pronounced agglomeration and a flocculation degree of about 4.3MPa at 145℃.In contrast,static flocculation exhibited a fundamentally different mechanism dominated by polymer chain dynamics,which is driven mainly by thermal activation.Radial distribution function (RDF) analysis of transmission electron microscopy (TEM) images revealed a slight decrease (2 nm) in the interparticle distance peak after static annealing at 100℃ for 7 h,indicating localized motion of CB particles.However,the overall filler network remained stable,with no significant agglomeration observed.The increase in bound rubber content from about 23% to 28% with rising temperature further confirmed the dominant role of polymer chain adsorption and interfacial reinforcement in static flocculation.These findings highlight the critical influence of external strain on filler network formation and provide new insights into the polymer-dominated mechanism of static flocculation.The results offer practical guidance for optimizing the storage and processing of rubber nanocomposites,particularly in applications where static flocculation during prolonged storage is a concern.
基金supported by the National Natural Science Foundation of China(Nos.52174239 and 52374259)the Program of China Scholarship Council(No.202406080114)Natural Sciences and Engineering Research Council of Canada(No.NSERC RGPIN 2024-04570).
文摘Chalcopyrite is often intergrown with talc,which,after grinding,forms ultrafine particles(<10μm)that readily coat chalcopyrite surfaces,hindering flotation and causing significant losses in tailings.This study evaluates polyvinyl acetate(PVAc),a thermoplastic polymer,as a selective flocculant to enhance reverse flot ation separation of chalcopyrite from ultrafine talc.Flotation tests showed that at a PVAc dosage of 40 mg/L,talc can be effectively and selectively removed,enabling efficient separation.Laser particle size analysis and scanning electron microscopy-energy dispersive spectrometry(SEM-EDS)confirmed that PVAc promotes selective talc aggregation without affecting chalcopyrite.X-ray photoelectron spectroscopy(XPS)and density functional theory(DFT)calculations revealed that hydrogen bonding between PVAc ester groups and surface hydroxyls on talc drives the flocculation,while chalcopyrite lacks suitable binding sites.PVAc adsorption also enhances talc hydrophobicity.Furthermore,particle-bubble coverage angle measurements and extended Derjaguin-Landau-Verwey-Overbeek(DLVO)theory theoretical calculations demonstrated that PVAc-induced flocculation increases attractive interactions between talc and bubbles,shifting the total interaction energy from repulsive to attractive and promoting bubble-particle attachment.This study clarifies the selective adsorption and flocculation mechanisms of PVAc and reveals the coupling of flocculation and flotation of ultrafine talc from a particle-bubble capture perspective,while expanding the potential of ester-based polymers for ultrafine mineral recovery.
基金supported by the Program for Guangdong Introducing Innovative and Entrepreneurial Teams(No.2019ZT08L213)the National Natural Science Foundation of China(No.42277101).
文摘Hypersaline mariculture wastewater necessitates treatment prior to its discharge into marine environments.Algal-mycelial pellets(AMPs),known for their cost-effectiveness,energy efficiency and sustainability,have not been previously explored for their flocculation and pollutant removal capabilities in hyperhaline conditions.This work employed an orthogonal test design to investigate the effects of nine factors at three levels on the treatment efficiency of mariculture wastewater using Chlorella sp.TNBR1 and Aspergillus niger AMPs.The comprehensive optimal conditions for achieving the highest flocculation efficiency and pollutant removal are determined to be a temperature of 30℃,light intensity of 6000 lux,a 12:0 light-dark cycle,an initial pH of 6,amicroalgal density of 11.25×10^(6)cell/mL,microalgal growth phase at the early logarithmic stage,a fungal spore density of 9.00×10^(5)spore/mL and a fungal pellet phase of 60 h.Under such conditions,the treatment of nonsterile actual mariculture wastewater with Chlorella sp.TNBR1 and Aspergillus niger AMPs results in a 93.35%±7.20%reduction in chemical oxygen demand(COD),92.83%±7.29%reduction in total nitrogen(TN),100%removal of total phosphorus(TP),and a flocculation efficiency of 69.21%±5.36%.These findings confirm that AMPs are a viable solution for effectively treating COD,TN and TP in real hypersaline mariculture wastewater,while also facilitating the flocculation and harvesting of microalgae.
基金Project (20062026) supported by Natural Science Foundation of Liaoning Province, China
文摘Effects of stirring speed and time, pH and sodium oleate concentration on the shear hydrophobic flocculation of ultrafine Anshan hematite with sodium oleate as the surfactant were discussed. The results show that these parameters significantly affect the shear hydrophobic flocculation of ultrafine hematite. The optimum conditions for the flocculation are： stirring speed 1 400 r/min, flocculation time 20 min, pH 9 and sodium oleate concentration 3.94×10-4 mol/L; the flotation recovery of hematite flocs is remarkably high compared with non flocculated ultrafine hematite. According to the extended DLVO theory, the total interaction potential of Anshan ultrafine hematite was determined. The calculation results indicate that the hydrophobic flocculation state of the ultrafine hematite-sodium oleate system is mainly dominated by electric double layer repulsive interaction potential and hydrophobic interaction potential. A mechanical agitation is required to impart particles a kinetic energy to overcome potential barrier between them due to the existence of electric double layer repulsive interaction potential. Those particles further approach to form flocs due to the significant increase of the hydrophobic interaction potential.
基金Project(2012BAC09B02)supported by the 12th-Five Years Key Programs for Science and Technology Development of ChinaProject(2015zzts078)supported by the Fundamental Research Funds for the Central Universities of Central South University,ChinaProject(2015CX005)supported by Innovation Driven Plan of Central South University,China
文摘In order to accelerate the sedimentation of super-large-scale argillized ultrafine tailings with bad features such as low settling velocity, muddy overflow water, and large flocculant dosage, a fly-ash-based magnetic coagulant （FAMC） was used in a dynamic experimental device. To obtain the best possible combination of the impact factors （magnetic intensity, FAMC dosage, flocculant dosage, and feed speed） for minimum overflow turbidity, a response surface methodology test coupled with a four-factor five-level central composite design was conducted. The synergy mechanism of FAMC and flocculant was analyzed based on the potential measurement and scanning electron microscopy. The results show that the flocculant dosage, overflow turbidity, and solid content can be reduced by 50%, 90%, and 80%, while the handling capacity per unit and efficiency of backfill and dry stacking can be promoted by 20%, 17%, and 13%, respectively, with a magnetic intensity of 0.3 T, FAMC dosage of 200 mL/t, flocculant dosage of 30 g/t, and feed speed of 0.6 t/（m^2·h）. Therefore, synergy of FAMC and flocculant has obvious efficiency in saving energy and protecting the environment by allowing 70×10^6 t/a of argillized ultrafine tailings slurry to be disposed safely and efficiently with a cost saving of more than 53×106 Yuan/a, which gives it great promise for use in domestic and foreign mines.
基金Project (2009ZX07212-001-01) supported by the Major Science and Technology Program for Water Pollution Control and Treatment,ChinaProject (50925417) supported by the National Natural Science Foundation for Distinguished Young Scholars of ChinaProjects (50830301,51074191) supported by the National Natural Science Foundation of China
文摘A novel inorganic polymer flocculant,poly-ferric sulfate（BPFS） was prepared by oxidation of ferrous sulfate using domestic Thiobacillus ferrooxidans（T·f） under acid condition.The optimal conditions for the preparation were pH value of 1.5,（NH4）2SO4 dosage of 0.5 g/L,initial Fe2＋ concentration of 45g/L,inoculum 10%,rotating speed of 120 r/min,reaction time of 5-6 d and reaction temperature of 30 ℃.Under the optimal conditions,the BPFS product with pH value of 1.5-2.2,basicity of 17.5%-22.7% and total iron content of 43.87-45.24 g/L was obtained.The application of the BPFS to three wastewaters was carried out,and the removal efficiencies of COD,decolorization and Zn2＋ by BPFS can be reached 70%,90% and 99%,respectively.The result suggests that the BPFS is an excellent flocculant for water treatment.
基金Supported by National Natural Science Foundation of China(51064011)Jiangxi Education Science " Twelfth Five-year" Planning Program (10YB335)Science Foundation for Youths of Jiangxi Educational Committee (GJJ09599)~~
文摘[Objective] To screen out a microbial flocculant with good decolorization effect on methyl orange wastewater,and study the effect of different cultural conditions on decolorization effect of methyl orange.[Method] Absorbance of methyl orange solution before and after decolorization was determined by spectrophotometer,and the decolorization rate was calculated to compare the effects of different cultural conditions on removal rate of methyl orange.[Result]An optimal actinomycete stain（F-1-2） was screened out,and the best cultural condition was as follows：with sucrose as carbon source and NaNO3 as nitrogen source,cultured in constant temperature oscillator at 150 r/min,30℃ for 72 h.Under the optimal condition,the removal rate against methyl orange could reach 68.4%.[Conclusion]Different culture conditions have great impact on decolorization effect of strain.
基金Supported by Special Project of Graduate Research and Innovation(2009)National Natural Science Foundation of China (30700010)Special Fund for Agro-scientific Research in the Public Interest(200803033)~~
文摘[Objective] The aim was to indentify a bioflocculatnt producing strain W5 isolated from soil samples and analyze its flocculating characteristics. [Method] The universal primers of bacterial 16S rDNA were used for PCR amplification of its genome; effects of the medium pH,carbon and nitrogen sources on its flocculating activity were analyzed by using single factor method; and infrared spectroscopy was used for functional groups analysis. [Result] The results of homology comparison showed that strain W5 belonging to Gram-negative,long bacilli and had 98.34% of homology with Hymenobacter gelipurpurascens,. In addition,the optimum carbon source,nitrogen source,pH for fermentation condition were glucose,yeast extract and pH 7.04,respectively. Microbe flocculant produced by W5 strain （MBF-W5） was extracted and purified to obtain reddish and flocculent products. Fourier-transform infrared （FTIR） spectroscopy indicated that the major functional groups of MBF-W5 were hydroxyl,carboxyl and amino. [Conclusion] More than 85% of flocculating activity was achieved under the conditions of 150-500 μl bioflocculation dosage,5-65 ℃ temperature and pH 2-10.
基金Supported by the Science Research Project of Qingdao Technical College in 2012(12-A-2)~~
文摘[Objective] This study aimed to screen a bacterial strain capable of producing bioflocculant. [Method] A bacterial strain T-11 capable of producing bioflocculant was isolated from activated sludge. Detailed tests on the morphological, physiological and biochemical characteristics were carried out and identification was performed to identify the strain. Finally, the bioflocculant was isolated and purified, and the flocculating activity and chemical characteristics were measured. [Result] It was identified as Serratia plumuthica based on its morphological, physiological and biochemical characteristics. This strain secreted flocculant best in a culture medium which included sucrose and NaNO3. The maximal cell growth was achieved within 10 h and the flocculating activity paralleled to it. It was found to be effective for flocculation of kaolin suspension, when added at a final concentration of 0.7 mg/L, over a range of pHs （2-7）, and temperature （approximately 30-80 ℃）. Chemical analysis indicated that the bioflocculant was an acidic polysaccharide consisting of glucose, glucuronic acid and galactose, talose and altrose. Infrared spectrum analysis also revealed typical characteristics of polysaccharides. [Conclusion] The biofloccu- lants produced by strain T-11 can greatly improve the ability of activated sludge to settle.
基金Project (2005CB623701) supported by the National Basic Research Program of China
文摘The effect of electrolyte on settling behavior of kaolinite was studied. Effects of hard water on selective flocculation of diasporic bauxite was tested and the measures were taken to eliminate the effects of Ca2＋ and Mg2＋ in hard water. The results indicated that, not only the concentration of electrolyte ions but also the ionic valence of the electrolyte ions affects the settling behavior of kaolinite; hard water significantly affects its selective flocculation owing to Ca2＋ and Mg2＋; general dispersants could not eliminate the effects of Ca2＋ and Mg2＋. Self-made softening agent in our lab could weaken or eliminate the effects of hard water on flocculation processes. The results of molecular dynamics simulation show that softening agent molecules could restrict Ca2＋ and prevent them from playing their roles, so as to eliminate the effects. The continuous pilot experiment results of bauxite flocculation were even better than those obtained in laboratory.
基金financially supported by the National Key R&D Program of China(No.2017YFC0804601)the National Natural Science Foundation of China(Nos.51804134and 51804135)+2 种基金the Natural Science Foundation of Jiangxi Province(No.20181BAB216013)the Program of Qingjiang Excellent Young Talents,Jiangxi University of Science and Technologythe Doctoral Startup Fund of Jiangxi University of Science and Technology(No.jxxjbs17011)。
文摘The composition of tailings particles in mines plays a key role in the flocculation settlement of slurries.To study the influence of coarse particle tailings(CPTs)on the flocculation settlement of tailings slurries(TSs),static flocculent settling tests,scanning electron microscopy observations,and laser particle size analyses were conducted using the tailings obtained from a copper mine.The results demonstrate that(i)in the accelerated and free settling process,CPTs did not directly settle at the bottom of graduated cylinders;instead,they were netted by the flocculent structures(FSs)and settled together more quickly.The CPTs accelerate the rapid settlement of TSs;the acceleration effect is more obvious when the CPTs content is greater than 50 wt%.(ii)The most appropriate flocculant unit consumption(FUC)is 20 g·t-1,and no substantial increase is observed in the flocculant settling velocity with an increase in the flocculant because the effective FSs did not substantially change and thus did not lead to a notable increase in the settling velocity of the solid–liquid interface(SLI).(iii)In the effective settling space of the thickening facility,free water quickly flowed from the pores of FSs,which is reflected in the period from 0 to 1 min.
基金supported by the National Natural Science Foundation of China (No. 51578069)
文摘As a special biofilm structure,microbial attachment is believed to play an important role in the granulation of aerobic granular activated sludge（AGAS）.This experiment was to investigate the biological effect of Ca^2＋,Mg^2＋,Cu^2＋,Fe^2＋,Zn^2＋,and K＋which are the most common ions present in biological wastewater treatment systems,on the microbial attachment of AGAS and flocculent activated sludge（FAS）,from which AGAS is always derived,in order to provide a new strategy for the rapid cultivation and stability control of AGAS.The result showed that attachment biomass of AGAS was about 300%higher than that of FAS without the addition of metal ions.Different metal ions had different effects on the process of microbial attachment.FAS and AGAS reacted differently to the metal ions as well,and in fact,AGAS was more sensitive to the metal ions.Specifically,Ca^2＋,Mg^2＋,and K＋could increase the microbial attachment ability of both AGAS and FAS under appropriate concentrations,Cu^2＋,Fe^2＋,and Zn^2＋were also beneficial to the microbial attachment of FAS at low concentrations,but Cu^2＋,Fe^2＋,and Zn^2＋greatly inhibited the attachment process of AGAS even at extremely low concentrations.In addition,the acylated homoserine lactone（AHL）-based quorum sensing system,the content of extracellular polymeric substances and the relative hydrophobicity of the sludges were greatly influenced by metal ions.As all these parameters had close relationships with the microbial attachment process,the microbial attachment may be affected by changes of these parameters.
基金Supproted by the Key Project of Chinese Ministry of Education(211189)~~
文摘[Objective] The purpose was to select out and identify a flocculant producing strain which could produce high active flocculant.[Method] The strain producing high active flocculant was isolated out and purified through medium culture and the selected strain was identified through observing its culture characters and determining its physiological and biochemical property.[Result] Fourteen strains of bacteria with flocculant producing function were isolated from tested soil samples through isolation,purification and preliminary screening using dilution-spread plate method and plate streaking method.Five strains of flocculant producing bacteria showing higher flocculation activity were selected out after second screening and their flocculation rates were higher than 70%;the flocculation activity of one strain among them was still stable after multiple subculturings,its flocculation rate was always above 90% and it was marked as TS-1.TS-1 was encapsulated Gram-positive bacillus and there was no lipid in it,such as poly-β-hydroxybutyric acid.TS-1 was Bacillus amyloliquefaciens,so it was named Bacillus TS-1.[Conclusion] The strain selected out in this experiment could be used in the flocculation and biochemical treatment of wastewater from starch industry.
基金Project(51274255)supported by the National Natural Science Foundation of ChinaProject supported by the Foundation of State Key Laboratory of Comprehensive Utilization of Low-Grade Ores(Zijin Mining Group Co.,Ltd),China
文摘The hydrophobic flocculation of marmatite fines in aqueous suspensions induced by butyl xanthate （KBX） and ammonium dibutyl dithiophosphate （ADD） was investigated using laser particle size analysis, microscopy analysis, electrophoretic light scattering, contact angle measurement and infrared spectroscopy. The studies were performed on single minerals with size 〈20 μm by varying several parameters, including pH, collector concentration and kerosene addition. The results show that the floc fotation closely correlated with the size of flocs and the particle hydrophobicity, but was not lowered with increasing the particle surface charges due to collector adsorption. Under good operating conditions, the floc flotation of marmatite fines as a function of KBX and ADD can all reach floatability over 90%, in comparison with conventional flotation obtaining floatability of about 60%. It also has been found that a small addition of kerosene greatly improved the floc flotation because of the formation of oil films on marmatite particles. The results of FTIR spectra indicate that adsorption of the two collectors onto marmatite were chemical adsorption.
基金Supported by Scientific Research Foundation of Yunnan Provincial Education Department(09Y0292)~~
文摘[Objective] The technological parameter suitable for the dewatering of dredged sediment from Dianchi Lake was studied.[Method] By means of the treatment method of sewage sludge in sewage treatment plant,flocculants including FeCl3,Al2(SO4)3 and PAM were taken as dewatering agents which were added in dredged sediment.[Result] The results showed that Al2(SO4)3 had better dewatering effect than FeCl3 and PAM,and the optimum dosing quantity of Al2(SO4)3 in dredged sediment was 170 mg/L,in addition,the water quality of supernatant met the first class B standard of GB18918-2002 and could be directly discharged to nature water without pollution.[Conclusion] The study could provide a simple and feasible way for the rapid dewatering of dredged sediment from Dianchi Lake,which would be convenient for the disposal and resource utilization of dredged sediment.
基金Supported by the Science Foundation of Shanghai MunicipalCommission of Education!( 97A2 6 )
文摘In this paper, the conditions of modified melamine formaldehyde resin (MF) used for a flocculent such as the ratio of reactant, reaction time, reaction temperature and the value of pH, were studied. The preferable synthetic conditions were melamine:formaldehyde:acrylamide (mole)=1:5:(2～3), reaction temperature 70 ℃, reaction time 4 h, pH 9.0.
基金supported by the National Natural Science Foundation of China (No. 50578089,21077066)the Key Projects in the National Science & Technology Pillar Program in the Eleventh Five-year Plan Period (No. 2006BAJ08B05-2)+2 种基金the Scientific Technology Research and Development Program of Shandong of China (No. 2009GG10006003 2010GZX20605)the Natural Science Foundation of Shandong Province of China (No. ZR2010BM014)
文摘A coagulation/flocculation process using the composite flocculant polyaluminum chloride-epichlorohydrin dimethylamine （PAC- EPI-DMA） was employed for the treatment of an anionic azo dye （Reactive Brilliant Red K-2BP dye）. The effect of viscosity 01）, basicity （B = [OH]/[Al]） and organic content （Wp） on the flocculation performance as well as the mechanism of PAC-EPI-DMA flocculant were investigated. The η was the key factor affecting the dye removal efficiency of PAC-EPI-DMA. PAC-EPI-DMA with an intermediate η （2400 mPa.sec） gave higher decolorization efficiency by adsorption bridging and charge neutralization due to the co-effect of PAC and EPI-DMA polymers. The Wp of the composite flocculant was a minor important factor for the flocculation. The adsorption bridging of PAC-EPI-DMA with η of 300 or 4300 mPa.sec played an important role with the increase of Wp, whereas the charge neutralization of them was weaker with the increase of Wp. There was interaction between Wp and B on the removal of reactive dye. The composite flocculant with intermediate viscosity and organic content was effective for the treatment of reactive dyeing wastewater, which could achieve high reactive dye removal efficiency with low organic dosage.
