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 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
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
The clay mineral flocculation encapsulation poses a major technical challenge in the field of fine mineral separation.Enhancing the ability to separate clay minerals from target mineral surfaces is key to addressing t...The clay mineral flocculation encapsulation poses a major technical challenge in the field of fine mineral separation.Enhancing the ability to separate clay minerals from target mineral surfaces is key to addressing this issue.In the flotation process of ultrafine hematite,sodium polyacrylate(PAAS)was used as a selective flocculant for hematite,polyaluminum chloride(PAC)as a flocculant for kaolinite and chlorite,and sodium oleate(NaOL)as the collector to achieve asynchronous flocculation flotation.This study examines the flotation separation performance and validates it through experiments on actual mineral samples.The results indicate that with PAAS and PAC dosages of 1.25 and 50 mg·L^(-1),respectively,the iron grade and recovery of the actual mineral samples increased by 9.39%and 7.97%.Through Zeta potential,XPS analysis,infrared spectroscopy,and total organic carbon(TOC)testing,the study reveals the microscopic interaction mechanisms of different flocculants with minerals,providing insights for the clean and efficient utilization of ultrafine mineral resources.展开更多
A series of novel chitosan-based magnetic flocculants FS@CTS-P(AM-DMC)was prepared by molecular structure control.The characterization results showed that FS@CTS-P(AM-DMC)had a uniform size of about 21.46 nm,featuring...A series of novel chitosan-based magnetic flocculants FS@CTS-P(AM-DMC)was prepared by molecular structure control.The characterization results showed that FS@CTS-P(AM-DMC)had a uniform size of about 21.46 nm,featuring a typical core-shell structure,and the average coating layer thickness of CTS-P(AM-DMC)was about 5.03 nm.FS@CTS-P(AM-DMC)exhibited excellent flocculation performance for kaolin suspension,achieved 92.54% turbidity removal efficiency under dosage of 150 mg/L,pH 7.0,even at high turbidity(2000 NTU)with a removal efficiency of 96.96%.The flocculation mechanism was revealed to be dominated by charge neutralization under acidic and neutral conditions,while adsorption and bridging effects play an important role in alkaline environments.The properties of magnetic aggregates during flocculation,breakage,and regeneration were studied at different pH levels and dosages.In the process of magnetophoretic,magnetic particles collide and adsorb with kaolin particles continuously due to magnetic and electrostatic attraction,transform into magnetic chain clusters,and then further form three-dimensional network magnetic aggregates that can capture free kaolin particles and other chain clusters.Particle image velocimetry confirmed the formation of eddy current of magnetic flocs and experienced three stages:acceleration,stabilization,and deceleration.展开更多
A type of high molecular weight bioactive polymers called exopolysaccharides(EPS)are produced by thermophiles,the extremophilic microbes that thrive in acidic environmental conditions of hot springs with excessively w...A type of high molecular weight bioactive polymers called exopolysaccharides(EPS)are produced by thermophiles,the extremophilic microbes that thrive in acidic environmental conditions of hot springs with excessively warm temperatures.Over time,EPS became important as natural biotechnological additives because of their noncytotoxic,emulsifying,antioxidant,or immunostimulant activities.In this article,we unravelled a new EPS produced by Staphy-lococcus sp.BSP3 from an acidic(pH 6.03)San Pedro hot spring(38.1℃)located in the central Andean mountains in Chile.Several physicochemical techniques were performed to characterize the EPS structure including Scanning electron microscopy-energy dispersive X-ray spectroscopy(SEM-EDS),Atomic Force Microscopy(AFM),High-Performance Liquid Chromatography(HPLC),Gel permeation chromatography(GPC),Fourier Transform Infrared Spectroscopy(FTIR),1D Nuclear Magnetic Resonance(NMR),and Thermogravimetric analysis(TGA).It was confirmed that the amorphous surface of the BSP3 EPS,composed of rough pillar-like nanostructures,is evenly distributed.The main EPS monosaccharide constituents were mannose(72%),glucose(24%)and galactose(4%).Also,it is a medium molecular weight(43.7 kDa)heteropolysaccharide.NMR spectroscopy demonstrated the presence of a[→6)-α-d-Manp-(1→6)-α-d-Manp-(1→]backbone 2-O substituted with 1-α-d-Manp.A high thermal stability of EPS(287°C)was confirmed by TGA analysis.Emulsification,antioxidant,flocculation,water-holding(WHC),and oil-holding(OHC)capacities are also studied for biotechnological industry applications.The results demonstrated that BSP3 EPS could be used as a biodegradable material for different purposes,like flocculation and natural additives in product formulation.展开更多
Deep-sea sediment disturbance may occur when collecting polymetallic nodules,resulting in the creation of plumes that could have a negative impact on the ecological environment.This study aims to investigate the poten...Deep-sea sediment disturbance may occur when collecting polymetallic nodules,resulting in the creation of plumes that could have a negative impact on the ecological environment.This study aims to investigate the potential solution of using polyaluminum chloride(PAC)in the water jet.The effects of PAC are examined through a self-designed simulation system for deep-sea polymetallic nodule collection and sediment samples from a potential deep-sea mining area.The experimental results showed that the optimal PAC dose was found to be 0.75 g/L.Compared with the test conditions without the addition of PAC,the presence of PAC leads to a reduction in volume,lower characteristic turbidity,smaller diffusion velocity,and shorter settling time of the plume.This indicates that PAC inhibits the entire development process of the plume.The addition of PAC leads to the flocculation of mm-sized particles,resulting in the formation of cm-sized flocs.The flocculation of particles decreases the rate of erosion on the seabed by around 30%.This reduction in erosion helps to decrease the formation of plumes.Additionally,when the size of suspended particles increases,it reduces the scale at which they diffuse.Furthermore,the settling velocity of flocs(around 10^(-2) m/s)is much higher that of compared to sediment particles(around 10^(-5) m/s),which effectively reduces the amount of time the plume remains in suspension.展开更多
The vacuum-assisted prefabricated horizontal drain offers a promising method for strengthening soil slurry,allowing simultaneous filling and vacuum-dewatering via staged construction.However,there is limited research ...The vacuum-assisted prefabricated horizontal drain offers a promising method for strengthening soil slurry,allowing simultaneous filling and vacuum-dewatering via staged construction.However,there is limited research on the unique characteristics of staged filling.This study aims to investigate the vacuum consolidation process of staged-filled soil slurry through laboratory model tests and numerical simulations,also assessing the impact of anionic polyacrylamide.Comparative analyses are conducted between vacuum consolidation with and without anionic polyacrylamide,as well as self-weight consolidation without anionic polyacrylamide.Results reveal contour lines of excess pore pressure,water content,and soil strength forming an ellipse around the prefabricated horizontal drain board.During the consolidation process,a higher degree of consolidation,lower water content,and higher soil strength were observed closer to the prefabricated horizontal drain board.After treatment,the uppermost filling layer exhibits an average water content that was approximately 40%higher than the lower filling layer,and its average strength was about 60%lower.This discrepancy is primarily due to the absence of sealing on the top surface and the relatively short vacuum consolidation time caused by staged filling.The introduction of anionic polyacrylamide-induced flocculation significantly improves the initial consolidation rate but minimally affects the dewatering capacity of vacuum preloading.Using flocculant can enhance both the staged filling rate and soil strength(by 1e2 times).Additionally,employing a staggered arrangement between different prefabricated horizontal drain layers is advisable to prevent top-down penetration in areas with low soil strength.展开更多
Particle size is an important characteristic of suspended matter,and it contains crucial information about the deposition process.Suspended particle samples in the water mixing zone of the Changjiang River Estuary wer...Particle size is an important characteristic of suspended matter,and it contains crucial information about the deposition process.Suspended particle samples in the water mixing zone of the Changjiang River Estuary were collected in December 2016.Untreated original grain size and the decentralized grain size of the suspended particles were measured via a laser particle size analyzer.Morphological characteristics and the chemical composition of the suspended particles were also studied systematically using a scanning electron microscope(SEM)with an energy dispersive X-ray spectrometer(EDS).Then,the flocculation and sedimentation of suspended matter in the water mixing zone were explored by combining them with the water mixing processes in the estuary.The average particle size of suspended matter in the mixing zone of the Changjiang River Estuary ranges fromФ5.73 toФ7.98.The particle size distribution pattern is an abnormal model with a mainly unimodal pattern.In the freshwater area that was dominated by runoff,the suspended matter is mainly composed of fine particles,the settling velocity is slow,and the flocculation is weak.Floc particles were often seen in the mixing zone,with the flocs having a relatively large particle size,a low density and a loose structure appearing at the weak mixing zone;the flocs had a compacted structure in most areas of the mixing zone.The changes of suspended particle size in the estuarine mixing zone promote the settling and deposition of suspended matter,which has an important influence on the bed geomorphology and preservation of the fine suspended particles in the estuary.展开更多
Chemical flocculants are widely used in treating mature fine tailings(MFT)produced during bitumen extraction processes,among which polymers with high molecular weight(HMW)have demonstrated efficacy in dewatering and c...Chemical flocculants are widely used in treating mature fine tailings(MFT)produced during bitumen extraction processes,among which polymers with high molecular weight(HMW)have demonstrated efficacy in dewatering and clay flocculation.The long polymer chains carry sufficient functional groups to simultaneously interact with multiple clay surfaces,thereby modulating clay surface properties and facilitating the aggregation of clay particles.Significant efforts have been devoted to enhancing the flocculation and dewatering performance of polymer reagents.Despite some successes,the design of new and effective polymer flocculants with desired performance is hindered by the limited fundamental understanding of clay-polymer interaction mechanisms.In this work,interaction mechanisms between polymer flocculants and clay particles are reviewed.Solid flocculation by polymers can be driven by multiple mechanisms,either independently or in combination,due to the diverse properties and solution chemistry involved.Factors that affect the interactions are analyzed,with a particular focus on the effects of clay surface features,pH,ions,and asphaltene.Addressing ongoing debates regarding the synergy of multiple types of polymer segments,the influence of multi-valent ions,and the effects of amphiphilic asphaltene can significantly expedite the design of more effective flocculants and flocculation processes.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
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 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 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funded by the National Natural Science Foundation of China(No.52374265)the Central Guided Local Science and Technology Development Funding Program(No.236Z4106G)+1 种基金the Natural Science Foundation of Hebei Province(No.E2022209108)Key Projects of Hebei Provincial Department of Education(No.ZD2022059)。
文摘The clay mineral flocculation encapsulation poses a major technical challenge in the field of fine mineral separation.Enhancing the ability to separate clay minerals from target mineral surfaces is key to addressing this issue.In the flotation process of ultrafine hematite,sodium polyacrylate(PAAS)was used as a selective flocculant for hematite,polyaluminum chloride(PAC)as a flocculant for kaolinite and chlorite,and sodium oleate(NaOL)as the collector to achieve asynchronous flocculation flotation.This study examines the flotation separation performance and validates it through experiments on actual mineral samples.The results indicate that with PAAS and PAC dosages of 1.25 and 50 mg·L^(-1),respectively,the iron grade and recovery of the actual mineral samples increased by 9.39%and 7.97%.Through Zeta potential,XPS analysis,infrared spectroscopy,and total organic carbon(TOC)testing,the study reveals the microscopic interaction mechanisms of different flocculants with minerals,providing insights for the clean and efficient utilization of ultrafine mineral resources.
基金supported by the National Natural Science Foundation of China(No.51672028)the Fundamental Research Funds for the Central Universities(Nos.2015ZCQ-HJ-02 and 2015PY-08)。
文摘A series of novel chitosan-based magnetic flocculants FS@CTS-P(AM-DMC)was prepared by molecular structure control.The characterization results showed that FS@CTS-P(AM-DMC)had a uniform size of about 21.46 nm,featuring a typical core-shell structure,and the average coating layer thickness of CTS-P(AM-DMC)was about 5.03 nm.FS@CTS-P(AM-DMC)exhibited excellent flocculation performance for kaolin suspension,achieved 92.54% turbidity removal efficiency under dosage of 150 mg/L,pH 7.0,even at high turbidity(2000 NTU)with a removal efficiency of 96.96%.The flocculation mechanism was revealed to be dominated by charge neutralization under acidic and neutral conditions,while adsorption and bridging effects play an important role in alkaline environments.The properties of magnetic aggregates during flocculation,breakage,and regeneration were studied at different pH levels and dosages.In the process of magnetophoretic,magnetic particles collide and adsorb with kaolin particles continuously due to magnetic and electrostatic attraction,transform into magnetic chain clusters,and then further form three-dimensional network magnetic aggregates that can capture free kaolin particles and other chain clusters.Particle image velocimetry confirmed the formation of eddy current of magnetic flocs and experienced three stages:acceleration,stabilization,and deceleration.
基金funded by FONDECYT Regular,Grant Number 1231917 by ANID,Govt.of Chile.
文摘A type of high molecular weight bioactive polymers called exopolysaccharides(EPS)are produced by thermophiles,the extremophilic microbes that thrive in acidic environmental conditions of hot springs with excessively warm temperatures.Over time,EPS became important as natural biotechnological additives because of their noncytotoxic,emulsifying,antioxidant,or immunostimulant activities.In this article,we unravelled a new EPS produced by Staphy-lococcus sp.BSP3 from an acidic(pH 6.03)San Pedro hot spring(38.1℃)located in the central Andean mountains in Chile.Several physicochemical techniques were performed to characterize the EPS structure including Scanning electron microscopy-energy dispersive X-ray spectroscopy(SEM-EDS),Atomic Force Microscopy(AFM),High-Performance Liquid Chromatography(HPLC),Gel permeation chromatography(GPC),Fourier Transform Infrared Spectroscopy(FTIR),1D Nuclear Magnetic Resonance(NMR),and Thermogravimetric analysis(TGA).It was confirmed that the amorphous surface of the BSP3 EPS,composed of rough pillar-like nanostructures,is evenly distributed.The main EPS monosaccharide constituents were mannose(72%),glucose(24%)and galactose(4%).Also,it is a medium molecular weight(43.7 kDa)heteropolysaccharide.NMR spectroscopy demonstrated the presence of a[→6)-α-d-Manp-(1→6)-α-d-Manp-(1→]backbone 2-O substituted with 1-α-d-Manp.A high thermal stability of EPS(287°C)was confirmed by TGA analysis.Emulsification,antioxidant,flocculation,water-holding(WHC),and oil-holding(OHC)capacities are also studied for biotechnological industry applications.The results demonstrated that BSP3 EPS could be used as a biodegradable material for different purposes,like flocculation and natural additives in product formulation.
基金supported by the National Natural Science Foundation of China(Nos.52225107,U2106224,U1906234,51822904,and U1706223)the Fundamental Research Funds for the Central Universities(No.202041004)
文摘Deep-sea sediment disturbance may occur when collecting polymetallic nodules,resulting in the creation of plumes that could have a negative impact on the ecological environment.This study aims to investigate the potential solution of using polyaluminum chloride(PAC)in the water jet.The effects of PAC are examined through a self-designed simulation system for deep-sea polymetallic nodule collection and sediment samples from a potential deep-sea mining area.The experimental results showed that the optimal PAC dose was found to be 0.75 g/L.Compared with the test conditions without the addition of PAC,the presence of PAC leads to a reduction in volume,lower characteristic turbidity,smaller diffusion velocity,and shorter settling time of the plume.This indicates that PAC inhibits the entire development process of the plume.The addition of PAC leads to the flocculation of mm-sized particles,resulting in the formation of cm-sized flocs.The flocculation of particles decreases the rate of erosion on the seabed by around 30%.This reduction in erosion helps to decrease the formation of plumes.Additionally,when the size of suspended particles increases,it reduces the scale at which they diffuse.Furthermore,the settling velocity of flocs(around 10^(-2) m/s)is much higher that of compared to sediment particles(around 10^(-5) m/s),which effectively reduces the amount of time the plume remains in suspension.
基金supported by the Research Grants Council of Hong Kong Special Administrative Region Government of China(Grant Nos.15210322 and R5037-18)the financial support(Grant No.86902-00000240)from Shenzhen University.
文摘The vacuum-assisted prefabricated horizontal drain offers a promising method for strengthening soil slurry,allowing simultaneous filling and vacuum-dewatering via staged construction.However,there is limited research on the unique characteristics of staged filling.This study aims to investigate the vacuum consolidation process of staged-filled soil slurry through laboratory model tests and numerical simulations,also assessing the impact of anionic polyacrylamide.Comparative analyses are conducted between vacuum consolidation with and without anionic polyacrylamide,as well as self-weight consolidation without anionic polyacrylamide.Results reveal contour lines of excess pore pressure,water content,and soil strength forming an ellipse around the prefabricated horizontal drain board.During the consolidation process,a higher degree of consolidation,lower water content,and higher soil strength were observed closer to the prefabricated horizontal drain board.After treatment,the uppermost filling layer exhibits an average water content that was approximately 40%higher than the lower filling layer,and its average strength was about 60%lower.This discrepancy is primarily due to the absence of sealing on the top surface and the relatively short vacuum consolidation time caused by staged filling.The introduction of anionic polyacrylamide-induced flocculation significantly improves the initial consolidation rate but minimally affects the dewatering capacity of vacuum preloading.Using flocculant can enhance both the staged filling rate and soil strength(by 1e2 times).Additionally,employing a staggered arrangement between different prefabricated horizontal drain layers is advisable to prevent top-down penetration in areas with low soil strength.
基金The National Natural Science Foundation of China under contract No.42176077。
文摘Particle size is an important characteristic of suspended matter,and it contains crucial information about the deposition process.Suspended particle samples in the water mixing zone of the Changjiang River Estuary were collected in December 2016.Untreated original grain size and the decentralized grain size of the suspended particles were measured via a laser particle size analyzer.Morphological characteristics and the chemical composition of the suspended particles were also studied systematically using a scanning electron microscope(SEM)with an energy dispersive X-ray spectrometer(EDS).Then,the flocculation and sedimentation of suspended matter in the water mixing zone were explored by combining them with the water mixing processes in the estuary.The average particle size of suspended matter in the mixing zone of the Changjiang River Estuary ranges fromФ5.73 toФ7.98.The particle size distribution pattern is an abnormal model with a mainly unimodal pattern.In the freshwater area that was dominated by runoff,the suspended matter is mainly composed of fine particles,the settling velocity is slow,and the flocculation is weak.Floc particles were often seen in the mixing zone,with the flocs having a relatively large particle size,a low density and a loose structure appearing at the weak mixing zone;the flocs had a compacted structure in most areas of the mixing zone.The changes of suspended particle size in the estuarine mixing zone promote the settling and deposition of suspended matter,which has an important influence on the bed geomorphology and preservation of the fine suspended particles in the estuary.
基金the financial supports from National Natural Science Foundation of China(Grant number:52304071)MOE Key Laboratory of Petroleum Engineering(China University of Petroleum,Grant number:2462024PTJS002)。
文摘Chemical flocculants are widely used in treating mature fine tailings(MFT)produced during bitumen extraction processes,among which polymers with high molecular weight(HMW)have demonstrated efficacy in dewatering and clay flocculation.The long polymer chains carry sufficient functional groups to simultaneously interact with multiple clay surfaces,thereby modulating clay surface properties and facilitating the aggregation of clay particles.Significant efforts have been devoted to enhancing the flocculation and dewatering performance of polymer reagents.Despite some successes,the design of new and effective polymer flocculants with desired performance is hindered by the limited fundamental understanding of clay-polymer interaction mechanisms.In this work,interaction mechanisms between polymer flocculants and clay particles are reviewed.Solid flocculation by polymers can be driven by multiple mechanisms,either independently or in combination,due to the diverse properties and solution chemistry involved.Factors that affect the interactions are analyzed,with a particular focus on the effects of clay surface features,pH,ions,and asphaltene.Addressing ongoing debates regarding the synergy of multiple types of polymer segments,the influence of multi-valent ions,and the effects of amphiphilic asphaltene can significantly expedite the design of more effective flocculants and flocculation processes.
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.
