[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
A strain saccharomycete STSM-1 with high flocculanting activity was isolated from activated sludge with conventional methods. The high production rate and the low cost STSM-1 medium was obtained by selecting different...A strain saccharomycete STSM-1 with high flocculanting activity was isolated from activated sludge with conventional methods. The high production rate and the low cost STSM-1 medium was obtained by selecting different kinds of media, carbon source, nitrogen source and inorganic salt ion. The best flocculant-producing conditions were found by changing medium initial pH, culture temperature and ventilation flow. The best flocculating effect was obtained by changing positive ion types, density and concentration of flocculant.展开更多
In this study,ultrafine HfB_(2) powders with low oxygen were synthesized by a flocculating settling process which yielded ceramic precursors and subsequent carbo/borothermal reduction of the precursors.The liquid phas...In this study,ultrafine HfB_(2) powders with low oxygen were synthesized by a flocculating settling process which yielded ceramic precursors and subsequent carbo/borothermal reduction of the precursors.The liquid phase precursor method can achieve uniform mixing of components at the molecular level through multiple complexation reactions,and then realize the carbo/borothermal reduction reaction at a lower temperature to obtain ultrapure HfB2 powders.The as-resulted quasi-spherical HfB2 powders under the optimum conditions(atomic molar ratio M:B:C=1:2.8:10)calcined at 1500°C for 1 h have an average particle size of 205 nm and an oxygen content of 0.097 wt.%.Detailed analysis of the phase evolution of precursors shows that the formation of HfB2 particles is a mass diffusion mode from the external to internal HfO_(2)cores.We reveal that below 1300°C,HfC is not an intermediate product of HfB2 powder during the transition of precursors.Instead,HfC was formed as a by-product at high temperatures in the carbo/borothermal reduction process.The proposed formation mechanism of HfB_(2) is completely different from the traditional two-step transformation method.After the sintering of the ultrafine powders,the HfB_(2) ceramics show a relative density of 96.1%and superior mechanical properties compared to other works.Furthermore,by simply replacing the initial metal source,chlorinated group IV and V transitional metals(Ti,Zr,Ta,Nb)can also convert into high-purity and ultrafine diborides.This work shows that flocculating settling assisted carbo/borothermal reduction has potential in lot size production of various high-purity and ultrafine boride powders.展开更多
Screening of bioflocculant-producing microorganisms was carded out. A strain that secreted excellent bioflocculant was isolated from municipal sewage using the spread plate technique, identified as Klebsiella sp. by t...Screening of bioflocculant-producing microorganisms was carded out. A strain that secreted excellent bioflocculant was isolated from municipal sewage using the spread plate technique, identified as Klebsiella sp. by the analytical profile index （API） identification system, and named A9. Several important factors that had an effect on A9＇s bioflocculant-producing and flocculating activity were studied. A total of 4 g/L Kaolin suspension was used to measure the flocculating activity of the bioflocculant from A9. It was found that maltose and urea were Ag＇s best carbon and nitrogen sources, respectively, and the flocculating activity of the flocculating agent from A9 was markedly increased by the addition of trivalent cations such as Fe^3＋ and Al^3＋; furthermore, the bioflocculant produced by A9 was most effective when the pH value was 6.0.展开更多
A bioflocculant-producing mutator strain, NIM-192, was screened out through nitrogen ion implanting into F J-7 strain. The results showed that NIM-192 had good genetic stability and high flocculating activity, and the...A bioflocculant-producing mutator strain, NIM-192, was screened out through nitrogen ion implanting into F J-7 strain. The results showed that NIM-192 had good genetic stability and high flocculating activity, and the flocculating rate increased by 34.26% than that of the original. Sucrose, complex nitrogen source contained yeast extract, urea and pH 7.0～ 9.0 were chosen as the best carbon source, nitrogen source and initial solution pH for bioflocculant production, respectively. The bioflocculant kept high and stable flocculating activity at alkalinous reaction mixture with a pH beyond 7.0, while the flocculating activity was remarkably reduced when the reaction pH was lower than 7.0. Addition of many cations could obviously increase the flocculating rate, among which Ca^2＋ demonstrated the best effect. The bioflocculant had very strong acid-base stability and thermo-stability.The flocculating rate kept over 86% when pH of the bioflocculant was in a range of 3.0 ～ 12.0, and the change of flocculating activity was not great when heated at 100℃ for 60 rain.展开更多
A compound bioflocculant CBF,produced by mixed culture of Rhizobium radiobacter F2 and Bacillus sphaeicus F6, was investigated with regard to its production and flocculating properties. The optimization of the culture...A compound bioflocculant CBF,produced by mixed culture of Rhizobium radiobacter F2 and Bacillus sphaeicus F6, was investigated with regard to its production and flocculating properties. The optimization of the culture medium constituents including carbon source,nitrogen source and C / N ratio,metal ions and ionic strength on CBF production were studied. Flocculating properties of CBF were examined by a series of experiments and CBF had good flocculating activities in kaolin suspension with divalent cations and stable over wide range of p H. Studies of the flocculating properties revealed that the flocculation could be stimulated by cations Ca2+,Mg2+,Fe2+,Al3+and Fe3+. In addition,it was stable at 4-30 ℃ in the presence of Ca Cl2. It was found to be effective for flocculation of a kaolin suspension under neutral and weak alkaline conditions( p H 7. 0- 9. 0),and flocculating activities of higher than 95% were obtained when the CBF concentrations among 6- 14 mg / L at p H 8. 0. The results of this study indicate that CBF is a potential replacement of conventional synthetic flocculants and is widely applied in water treatment and downstream processing of food and fermentation industries.展开更多
After conducting a lot of screening experiments the appropriate flocculating formulations for treating high-concentration wastewater discharged from a certain refinery were selected. The oil removal rate and COD remov...After conducting a lot of screening experiments the appropriate flocculating formulations for treating high-concentration wastewater discharged from a certain refinery were selected. The oil removal rate and COD removal achieved by these flocculating formulations were better than that achieved by the conventional compound formulation consisting of polyaluminium chloride(PAC) and polyacrylamide(PAA) . Addition of an oil/water separating agent to the formulation could improve its oil removal performance to facilitate the oil/water separation of the oil-in-water emulsion in the high-concentration wastewater along with improved adaptability of the formulation to the wastewater containing high concentration of pollutants. This flocculating agent has promising prospects for commercial application.展开更多
The effects of Ca(2+) and Al(3+)ions on flocculating process of kaolin using plogycrylamide as flocculant was studied. Mechanism of the effects was investigated and discussed through molecularorbit(MO) theory , soluti...The effects of Ca(2+) and Al(3+)ions on flocculating process of kaolin using plogycrylamide as flocculant was studied. Mechanism of the effects was investigated and discussed through molecularorbit(MO) theory , solution chemistry calculation and electronic probe examination in this article.展开更多
Microbial flocculants have become a hot spot in recent years. A bacterial strain with high flocculating activity was isolated from seawater samples. The strain was defined as Bacillus licheniformis dhs-40 by 16S rDNA ...Microbial flocculants have become a hot spot in recent years. A bacterial strain with high flocculating activity was isolated from seawater samples. The strain was defined as Bacillus licheniformis dhs-40 by 16S rDNA identification and Biolog test. Ultrasonication test confirmed the flocculating activity of the strain was both in fermentation supernatant and cell. According to flocculating activity curve, the ideal fermentation time for collecting flocculating active substances was two days. The flocculating activity of the strain was sensitive to pH. The strain could only preserve flocculating activity while pH varied from 7 to 11. However, it could preserve flocculating activity while temperature varied from -20℃to 100 ℃ Saccharide, protein, lipid, nucleic acids qualitative test and RNase, Proteinase K treatment confirmed the flocculating active substances were proteins. Their flocculating activities were insensitive to Proteinase K.展开更多
Graft copolymerization is one of the most attractive methods to modify natural polymers. In this study, graft copolymerization of acylic acid onto chitosan in aqueous media by ceric ammonium nitrate was investigated. ...Graft copolymerization is one of the most attractive methods to modify natural polymers. In this study, graft copolymerization of acylic acid onto chitosan in aqueous media by ceric ammonium nitrate was investigated. The graft copolymerization reaction was carried out in a three necked flask maintained at 70＋/-0.05 ℃ under nitrogen atmosphere in a homogeneous aqueous phase （containing a small potion of acetic acid） by using ceric ammonium nitrate as an initiator. Evidence of grafting was obtained. The synthetic conditions were systematically optimized through studying the influential factors on grafting. The effectiveness of each individual factor was investigated by calculating and monitoring the variations of the grafting parameters [like monomer conversation Cm, grafting efficiency （Ge） and viscosity]. Under optimum conditions monomer conversion of 100.5% and graft efficiency of 94% were obtained, at temperature of 70℃. Flocculating ability of the copolymerization product of chitosan was studied by using Kaolin suspension as the flocculating object. And the application of the product was applied in Huayue dyeing plant. The results indicate that the higher the viscosity is, the better the flocculating ability of the copolymerization product of chitosan will be. The flocculating percentage reaches 96.0%, when the concentration of the product is only 1.0 mg/L and pH fixed at 7.0. Suitable separating mixtures for the grafted copolymer were chosen and the investigation of flocculation ability of the grafted copolymer was carried out with the aim of developing a good flocculant for wastewater treatment. A test of treating dyeing wastewater with the grafted copolymer was carried out and showed that grafting of Acrylic Acid with chitosan has a high COD removal rate 75% to the dyeing wastewater when the concentration is only 6.0 mg/L.展开更多
The flocculating properties of polymer-colloid complexes (PCCs) formed via noncovalent interactions of positively charged aluminoxane particles (APs) with macromolecules of weakly charged cationic acrylamide copolymer...The flocculating properties of polymer-colloid complexes (PCCs) formed via noncovalent interactions of positively charged aluminoxane particles (APs) with macromolecules of weakly charged cationic acrylamide copolymers from the Praestol and Organopol series have been studied. The PCCs that spontaneously formed during mixing of sols of a high-basicity aluminum polyhydroxochloride (APHC) with aqueous solutions of the copolymers exhibit high flocculating ability under the conditions of gravity sedimentation of the model kaolin dispersion with Сd = 8 g/dm3, and their efficiency exceeds both that of the copolymers and the earlier obtained PCCs with nonionogenic polyacrylamide (PAA). In contrast to weakly charged polycationites, the fully charged KF-99 polyelectrolyte does not form PCCs and the products of its mixing with APHC do not reveal an increased flocculating effect.展开更多
The chemical coagulation-flocculation technology is touted as one of the valuable techniques and widely used for wastewater treatment because of its simplicity and effectiveness. So far, a number of flocculants have b...The chemical coagulation-flocculation technology is touted as one of the valuable techniques and widely used for wastewater treatment because of its simplicity and effectiveness. So far, a number of flocculants have been fabricated to ameliorate the flocculation process in water treatment such as alum, polyaluminium chloride. Despite its broad application in water treatment, accumulation of alum in sludge has been reported as the main source of a disposal problem. Furthermore, recent studies suggested that the presence of alum in sludge may lead to human health problems. Here in, we have used alkalization method to recover alum present in sludge collected from Kimisagara water treatment plant located in Kigali capital city of Rwanda. The recovered alum was used more than one time and showed excellent flocculation efficiency. Some physical parameters such as pH, Total Suspended Solids (TSS), Total Dissolved Solids (TDS), Conductivity and Turbidity were systematically tested and compared with those of World Health Organization (WHO) and Rwanda Standards Board (RSB) standards for drinking water. The results showed that alum present in sludge can be recovered and reused for multiple times.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
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 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
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.
文摘A strain saccharomycete STSM-1 with high flocculanting activity was isolated from activated sludge with conventional methods. The high production rate and the low cost STSM-1 medium was obtained by selecting different kinds of media, carbon source, nitrogen source and inorganic salt ion. The best flocculant-producing conditions were found by changing medium initial pH, culture temperature and ventilation flow. The best flocculating effect was obtained by changing positive ion types, density and concentration of flocculant.
基金financially supported by the National Science Fund for Distinguished Young Scholars(No.51825103)the National Science Fund for Excellent Young Scholars(No.52222208)+1 种基金the Major science and technology project of Anhui Province(No.008192841048)the HFIPS Director's Fund,CAS(No.BJPY2021B04,YZJJ202202-CX,YZJJKX202202).
文摘In this study,ultrafine HfB_(2) powders with low oxygen were synthesized by a flocculating settling process which yielded ceramic precursors and subsequent carbo/borothermal reduction of the precursors.The liquid phase precursor method can achieve uniform mixing of components at the molecular level through multiple complexation reactions,and then realize the carbo/borothermal reduction reaction at a lower temperature to obtain ultrapure HfB2 powders.The as-resulted quasi-spherical HfB2 powders under the optimum conditions(atomic molar ratio M:B:C=1:2.8:10)calcined at 1500°C for 1 h have an average particle size of 205 nm and an oxygen content of 0.097 wt.%.Detailed analysis of the phase evolution of precursors shows that the formation of HfB2 particles is a mass diffusion mode from the external to internal HfO_(2)cores.We reveal that below 1300°C,HfC is not an intermediate product of HfB2 powder during the transition of precursors.Instead,HfC was formed as a by-product at high temperatures in the carbo/borothermal reduction process.The proposed formation mechanism of HfB_(2) is completely different from the traditional two-step transformation method.After the sintering of the ultrafine powders,the HfB_(2) ceramics show a relative density of 96.1%and superior mechanical properties compared to other works.Furthermore,by simply replacing the initial metal source,chlorinated group IV and V transitional metals(Ti,Zr,Ta,Nb)can also convert into high-purity and ultrafine diborides.This work shows that flocculating settling assisted carbo/borothermal reduction has potential in lot size production of various high-purity and ultrafine boride powders.
文摘Screening of bioflocculant-producing microorganisms was carded out. A strain that secreted excellent bioflocculant was isolated from municipal sewage using the spread plate technique, identified as Klebsiella sp. by the analytical profile index （API） identification system, and named A9. Several important factors that had an effect on A9＇s bioflocculant-producing and flocculating activity were studied. A total of 4 g/L Kaolin suspension was used to measure the flocculating activity of the bioflocculant from A9. It was found that maltose and urea were Ag＇s best carbon and nitrogen sources, respectively, and the flocculating activity of the flocculating agent from A9 was markedly increased by the addition of trivalent cations such as Fe^3＋ and Al^3＋; furthermore, the bioflocculant produced by A9 was most effective when the pH value was 6.0.
基金the State Key Development Program for Basic Research of China(No.2004CB719604)
文摘A bioflocculant-producing mutator strain, NIM-192, was screened out through nitrogen ion implanting into F J-7 strain. The results showed that NIM-192 had good genetic stability and high flocculating activity, and the flocculating rate increased by 34.26% than that of the original. Sucrose, complex nitrogen source contained yeast extract, urea and pH 7.0～ 9.0 were chosen as the best carbon source, nitrogen source and initial solution pH for bioflocculant production, respectively. The bioflocculant kept high and stable flocculating activity at alkalinous reaction mixture with a pH beyond 7.0, while the flocculating activity was remarkably reduced when the reaction pH was lower than 7.0. Addition of many cations could obviously increase the flocculating rate, among which Ca^2＋ demonstrated the best effect. The bioflocculant had very strong acid-base stability and thermo-stability.The flocculating rate kept over 86% when pH of the bioflocculant was in a range of 3.0 ～ 12.0, and the change of flocculating activity was not great when heated at 100℃ for 60 rain.
基金Sponsored by the National High Technology Research and Development Program of China(Grant No.2009AA062906)the"Twelfth Five-Year Plan"National Key Technology R&D Program of China(Grant No.2012BAD14B06-04)+2 种基金the National Natural Science Foundation of China(Grant No.51478140&51408200)State Key Laboratory of Urban Water Resource and Environment(Harbin Institute of Technology)(Grant No.2015DX06)Promising Youngsters Training Program of Heilongjiang University of Science and Technology(Grant No.Q20120201)
文摘A compound bioflocculant CBF,produced by mixed culture of Rhizobium radiobacter F2 and Bacillus sphaeicus F6, was investigated with regard to its production and flocculating properties. The optimization of the culture medium constituents including carbon source,nitrogen source and C / N ratio,metal ions and ionic strength on CBF production were studied. Flocculating properties of CBF were examined by a series of experiments and CBF had good flocculating activities in kaolin suspension with divalent cations and stable over wide range of p H. Studies of the flocculating properties revealed that the flocculation could be stimulated by cations Ca2+,Mg2+,Fe2+,Al3+and Fe3+. In addition,it was stable at 4-30 ℃ in the presence of Ca Cl2. It was found to be effective for flocculation of a kaolin suspension under neutral and weak alkaline conditions( p H 7. 0- 9. 0),and flocculating activities of higher than 95% were obtained when the CBF concentrations among 6- 14 mg / L at p H 8. 0. The results of this study indicate that CBF is a potential replacement of conventional synthetic flocculants and is widely applied in water treatment and downstream processing of food and fermentation industries.
文摘After conducting a lot of screening experiments the appropriate flocculating formulations for treating high-concentration wastewater discharged from a certain refinery were selected. The oil removal rate and COD removal achieved by these flocculating formulations were better than that achieved by the conventional compound formulation consisting of polyaluminium chloride(PAC) and polyacrylamide(PAA) . Addition of an oil/water separating agent to the formulation could improve its oil removal performance to facilitate the oil/water separation of the oil-in-water emulsion in the high-concentration wastewater along with improved adaptability of the formulation to the wastewater containing high concentration of pollutants. This flocculating agent has promising prospects for commercial application.
文摘The effects of Ca(2+) and Al(3+)ions on flocculating process of kaolin using plogycrylamide as flocculant was studied. Mechanism of the effects was investigated and discussed through molecularorbit(MO) theory , solution chemistry calculation and electronic probe examination in this article.
文摘Microbial flocculants have become a hot spot in recent years. A bacterial strain with high flocculating activity was isolated from seawater samples. The strain was defined as Bacillus licheniformis dhs-40 by 16S rDNA identification and Biolog test. Ultrasonication test confirmed the flocculating activity of the strain was both in fermentation supernatant and cell. According to flocculating activity curve, the ideal fermentation time for collecting flocculating active substances was two days. The flocculating activity of the strain was sensitive to pH. The strain could only preserve flocculating activity while pH varied from 7 to 11. However, it could preserve flocculating activity while temperature varied from -20℃to 100 ℃ Saccharide, protein, lipid, nucleic acids qualitative test and RNase, Proteinase K treatment confirmed the flocculating active substances were proteins. Their flocculating activities were insensitive to Proteinase K.
文摘Graft copolymerization is one of the most attractive methods to modify natural polymers. In this study, graft copolymerization of acylic acid onto chitosan in aqueous media by ceric ammonium nitrate was investigated. The graft copolymerization reaction was carried out in a three necked flask maintained at 70＋/-0.05 ℃ under nitrogen atmosphere in a homogeneous aqueous phase （containing a small potion of acetic acid） by using ceric ammonium nitrate as an initiator. Evidence of grafting was obtained. The synthetic conditions were systematically optimized through studying the influential factors on grafting. The effectiveness of each individual factor was investigated by calculating and monitoring the variations of the grafting parameters [like monomer conversation Cm, grafting efficiency （Ge） and viscosity]. Under optimum conditions monomer conversion of 100.5% and graft efficiency of 94% were obtained, at temperature of 70℃. Flocculating ability of the copolymerization product of chitosan was studied by using Kaolin suspension as the flocculating object. And the application of the product was applied in Huayue dyeing plant. The results indicate that the higher the viscosity is, the better the flocculating ability of the copolymerization product of chitosan will be. The flocculating percentage reaches 96.0%, when the concentration of the product is only 1.0 mg/L and pH fixed at 7.0. Suitable separating mixtures for the grafted copolymer were chosen and the investigation of flocculation ability of the grafted copolymer was carried out with the aim of developing a good flocculant for wastewater treatment. A test of treating dyeing wastewater with the grafted copolymer was carried out and showed that grafting of Acrylic Acid with chitosan has a high COD removal rate 75% to the dyeing wastewater when the concentration is only 6.0 mg/L.
文摘The flocculating properties of polymer-colloid complexes (PCCs) formed via noncovalent interactions of positively charged aluminoxane particles (APs) with macromolecules of weakly charged cationic acrylamide copolymers from the Praestol and Organopol series have been studied. The PCCs that spontaneously formed during mixing of sols of a high-basicity aluminum polyhydroxochloride (APHC) with aqueous solutions of the copolymers exhibit high flocculating ability under the conditions of gravity sedimentation of the model kaolin dispersion with Сd = 8 g/dm3, and their efficiency exceeds both that of the copolymers and the earlier obtained PCCs with nonionogenic polyacrylamide (PAA). In contrast to weakly charged polycationites, the fully charged KF-99 polyelectrolyte does not form PCCs and the products of its mixing with APHC do not reveal an increased flocculating effect.
文摘The chemical coagulation-flocculation technology is touted as one of the valuable techniques and widely used for wastewater treatment because of its simplicity and effectiveness. So far, a number of flocculants have been fabricated to ameliorate the flocculation process in water treatment such as alum, polyaluminium chloride. Despite its broad application in water treatment, accumulation of alum in sludge has been reported as the main source of a disposal problem. Furthermore, recent studies suggested that the presence of alum in sludge may lead to human health problems. Here in, we have used alkalization method to recover alum present in sludge collected from Kimisagara water treatment plant located in Kigali capital city of Rwanda. The recovered alum was used more than one time and showed excellent flocculation efficiency. Some physical parameters such as pH, Total Suspended Solids (TSS), Total Dissolved Solids (TDS), Conductivity and Turbidity were systematically tested and compared with those of World Health Organization (WHO) and Rwanda Standards Board (RSB) standards for drinking water. The results showed that alum present in sludge can be recovered and reused for multiple times.
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 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.
