[Objective] This study aimed to make use of the limited filamentous sludge bulking characteristics to purify water quality and save energy. [Method] The effects of dissolved oxygen （DO） on sludge bulking were explor...[Objective] This study aimed to make use of the limited filamentous sludge bulking characteristics to purify water quality and save energy. [Method] The effects of dissolved oxygen （DO） on sludge bulking were explored by changing the DO con- centration in the aerobiotic pool of NO system from the low load （0.25 kg COD/（kg MLSS.d）） and the medium to high load （0.55 kgCOD/（kg MLSSod））. [Result] In the NO activated sludge system, when the sludge load was 0.25 kg COD/（kg MLSS.d）, DO=1.5 mg/L, the sludge index was at around 250, while when the sludge load- ing was 0.55 kg COD/（kg MLSS.d）, DO=1.5 mg/L, the sludge index was close to 300, occurring the limited filamentous bulking. The bulked sludge still showed high removal rates to COD, SS, nitrogen and phosphorus. [Conclusion] It could improve the oxygen transfer rate and reduce the aeration rate at low DO conditions to achieve energy-saving.展开更多
The present study examines the results of the researches related to the gob bulking factor carried out at home and abroad.A mathematical function of a three-dimensional gob bulking factor is described based on a three...The present study examines the results of the researches related to the gob bulking factor carried out at home and abroad.A mathematical function of a three-dimensional gob bulking factor is described based on a three-dimensional gob model.The method of taking value for interstice and permeability ratios is also proposed.The law of air leakage of fully mechanized top coal is researched in this study.The results show that the speed of air flow near the upper and lower crossheadings is higher than that in the central section of the gob at the same distance from the working face.When the amount of air at the working face exceeds a critical amount,the width of the spontaneous combustion zone in the upper and lower crossheadings is also larger than that in the central section.In this situation,the key is preventing the coal left in the upper and lower crossheadings from self-igniting.Reducing the amount of air at the working face can decrease the width of the spontaneous combustion zone,especially the width near the upper and lower crossheadings.This also moves the spontaneous combustion zone in the direction of the working face.It can prevent the coal in the gob from self-igniting by making the coal left in the crossheadings to be inert and by effectively controlling the amount of air at the working face.展开更多
Static aerobic composting of municipal sewage sludge with forced ventilation or air ventilation using matured compost as bulking conditioner was investigated. Physical and chemical parame ,eters, e.g., temperature, mo...Static aerobic composting of municipal sewage sludge with forced ventilation or air ventilation using matured compost as bulking conditioner was investigated. Physical and chemical parame ,eters, e.g., temperature, moisture content, VSS, CODcr, pH, and germination index （GI）, were analyzed to characterize the composting process. Fermentation starts quickly in both forced and air ventilation compost heaps and reaches high-temperature stage after 2 d, owing to the bulking function of matured compost. Compared to air ventilation, however, forced ventilation enables the high-temperature stage to last longer for approximately 7 d. The moisture content of both compost bodies decreases from 62% to about 50% as a result of evaporation, and it decreases slightly faster in forced ventilation compost heap after 13 d due to the higher temperature and better ventilation condition. Although no obvious differences of VSS and pH are observed between both compost heaps, the soluble CODcr and GI show differences during the second half period of fermentation. In forced ventilation compost, the soluble CODcr has a small rebound after 13 d, and GI decreases from 46% to 35% but then increases. These results show that in general, the matured compost is a good conditioner and force ventilation with a proper air supply strategy can be more efficient than air ventilation.展开更多
Bulking characteristics of gangue are of great significance for the stability of goafs in mining overburden in the caving zones.In this paper,a particle discrete element method with clusters to represent gangue was ad...Bulking characteristics of gangue are of great significance for the stability of goafs in mining overburden in the caving zones.In this paper,a particle discrete element method with clusters to represent gangue was adopted to explore the bulking coefficient time effect of the broken rock in the caving zone under three-dimensional triaxial compression condition.The phenomena of stress corrosion,deformation,and failure of rock blocks were simulated in the numerical model.Meanwhile,a new criterion of rock fragments damage was put forward.It was found that the broken rock has obvious viscoelastic properties.A new equation based on the Burgers creep model was proposed to predict the bulking coefficient of broken rock.A deformation characteristic parameter of the prediction equation was analyzed,which can be set as a fixed value in the mid-and long-term prediction of the bulking coefficient.There are quadratic function relationships between the deformation characteristic parameter value and Talbot gradation index,axial pressure and confining pressure.展开更多
Viscous sludge bulking is a rare phenomenon in activated sludge process.The performances of nutrients removal were investigated with normal sludge and viscous bulking sludge.The results showed that when COD loading an...Viscous sludge bulking is a rare phenomenon in activated sludge process.The performances of nutrients removal were investigated with normal sludge and viscous bulking sludge.The results showed that when COD loading and C/N ratio were around 0.13 mg COD/(mg MLSS·d)and 7.67,the effect of viscous sludge bulking on the maximum specific oxidation rates of NH_(4)^(+)⁃N was very little,while the maximum specific oxidation rates of NO_(2)^(-)⁃N decreased from 24.69 mg/(g·h)to 1.20 mg/(g·h).Compared with normal sludge,viscous bulking sludge had bigger particle size and more extracellular polymeric substances(EPS).The mass transfer resistance in sludge flocs might be the main cause of the difference in NO-2⁃N oxidation rates.Therefore,this study demonstrates that viscous sludge bulking is beneficial to enhance simultaneous nitrification and denitrification(SND),and excessive EPS will exhibit storage function during phosphorus removal process.展开更多
Sludge bulking property of membrane bio-reactor was investigated in this study through contrast research. When the sludge bulking appeared, the removal efficiency of COD in membrane bio-reactor increased slightly thro...Sludge bulking property of membrane bio-reactor was investigated in this study through contrast research. When the sludge bulking appeared, the removal efficiency of COD in membrane bio-reactor increased slightly through the function of filamentous bacteria. However, the negative effects of the higher net water-head differential pressures, the high block rate of membrane pore and the great quantity of filamentous bacteria at the external surface presented at the same time. Thus, plenty of methods should be performed to control sludge bulking once it happened in membrane bio-reactor.展开更多
Albumen wastewater was treated by Membrane Bio-reactor. Sludge bulking property of Membrane Bio-Reactor was investigated in this study through contrast research. When the sludge bulking appeared, the removal efficienc...Albumen wastewater was treated by Membrane Bio-reactor. Sludge bulking property of Membrane Bio-Reactor was investigated in this study through contrast research. When the sludge bulking appeared, the removal efficiency of COD in Membrane Bio-reactor increased slightly under the function of filamentous bacteria. However, the negative effects of the higher net water-head differential pressures,the higher block rate of membrane pore and the great quantity of filamentous bacteria at the externalsurface pres...展开更多
Background: Urinary incontinence mainly affects women regardless of age and, as it affects their quality of life, influences work, sex life and independence for activities of daily living. The treatment of stress urin...Background: Urinary incontinence mainly affects women regardless of age and, as it affects their quality of life, influences work, sex life and independence for activities of daily living. The treatment of stress urinary incontinence including urethral volume injection therapy can provide an intermediate option over non-surgical and surgical therapies. One of the mechanisms for stress continence depends on the effective coaptation of the urethra during the increase in intra-abdominal pressure. The bulking agents can be injected transurethral or periurethral retrogradely, using direct vision from a cystoscope. Purpose: To evaluate the feasibility and preliminary outcome performance of the bacterial polysaccharide gel used as biological bulking agent applied in female patients with stress urinary incontinence. Methods: A prospective clinical pilot study was performed, in a single institution, including female patients who were admitted to the urologic outpatient clinic with Stress Urinary Incontinence (SUI) without previous treatments and they were selected and underwent bulking agent procedure. The evaluation was performed at the time of enrollment and 6 months after treatment. The primary outcome was Quality of Life (QOL) using the ICIQ-SF Questionnaire. The amount of urine leakage measured by the 1-HOUR PAD-TEST was the second outcome. Results: Fifteen women (with an average age of 53 years) were submitted to the application of bacterial cellulose gel and she was analyzed. Only two patients presented unchanged incontinence. The study considered as primary outcome the improvement or disappearance of symptoms after six months of intervention. Post-intervention Quality of Life (QOL) questionnaire indicated that all of these patients related a better quality of life (62.5%). Through the PAD-test it was possible to observe a decrease in urinary leak of 85% comparing the results pre and post-intervention (BCA—Bacterial Cellulose Application) with p-value equal to 0.000009. Conclusions: The results of this pilot study suggest that the use of biological bulking agent is a promising approach to treat stress urinary incontinence in female patients. Trial registration: Registration number and date of registration should be instated in this section.展开更多
The use of hyaluronic acid and dextranomer (Solesta, Salix) injection in the anal canal is an emerging modal-ity in the treatment of fecal incontinence. However, little is known regarding the endoscopic and radiologic...The use of hyaluronic acid and dextranomer (Solesta, Salix) injection in the anal canal is an emerging modal-ity in the treatment of fecal incontinence. However, little is known regarding the endoscopic and radiological appearance following injection of this ano-rectal bulking agent. We report computed tomography and endoscopic findings after hyaluronic acid/dextranomer injection in the ano-rectal area.展开更多
Based on the characteristics of 3D bulk forming process, the arbitrary Lagrangian-Eulerian (ALE) formulation-based FEM is studied, and a prediction-correction ALE-based FEM is proposed which integrates the advantages ...Based on the characteristics of 3D bulk forming process, the arbitrary Lagrangian-Eulerian (ALE) formulation-based FEM is studied, and a prediction-correction ALE-based FEM is proposed which integrates the advantages of precisely predicting the boundary configuration of the deformed material, and of efficiently avoiding hexahedron remeshing processes. The key idea of the prediction-correction ALE FEM is elaborated in detail. Accordingly, the strategy of mesh quality control, one of the key enabling techniques for the 3D bulk forming process numerical simulation by the prediction-correction ALE FEM is carefully investigated, and the algorithm for hexahedral element refinement is formulated based on the mesh distortion energy.展开更多
The Voronoi grain-based breakable block model(VGBBM)based on the combined finite-discrete element method(FDEM)was proposed to explicitly characterize the failure mechanism and predict the deformation behavior of hard-...The Voronoi grain-based breakable block model(VGBBM)based on the combined finite-discrete element method(FDEM)was proposed to explicitly characterize the failure mechanism and predict the deformation behavior of hard-rock mine pillars.The influence of the microscopic parameters on the macroscopic mechanical behavior was investigated using laboratory-scale models.The field-scale pillar models(width-to-height,W/H=1,2 and 3)were calibrated based on the empirically predicted stress-strain curves of Creighton mine pillars.The results indicated that as the W/H ratios increased,the VGBBM effectively predicted the transition from strain-softening to pseudo-ductile behavior in pillars,and explicitly captured the separated rock slabs and the V-shaped damage zones on both sides of pillars and conjugate shear bands in core zones of pillars.The volumetric strain field revealed significant compressional deformation in core zones of pillars.While the peak strains of W/H=1 and 2 pillars were relatively consistent,there were significant differences in the strain energy storage and release mechanism.W/H was the primary factor influencing the deformation and strain energy in the pillar core.The friction coefficient of the structural plane was also an important factor affecting the pillar strength and the weakest discontinuity angle.The fracture surface was controlled by the discontinuity angle and the friction coefficient.This study demonstrated the capability of the VGBBM in predicting the strengths and deformation behavior of hard-rock pillars in deep mine design.展开更多
Layered oxide is a promising cathode material for sodium-ion batteries because of its high-capacity,high operating voltage,and simple synthesis.Cycling performance is an important criterion for evaluating the applicat...Layered oxide is a promising cathode material for sodium-ion batteries because of its high-capacity,high operating voltage,and simple synthesis.Cycling performance is an important criterion for evaluating the application prospects of batteries.However,facing challenges,including phase transitions,ambient stability,side reactions,and irreversible anionic oxygen activity,the cycling performance of layered oxide cathode materials still cannot meet the application requirements.Therefore,this review proposes several strategies to address these challenges.First,bulk doping is introduced from three aspects:cationic single doping,anionic single doping,and multi-ion doping.Second,homogeneous surface coating and concentration gradient modification are reviewed.In addition,methods such as mixed structure design,particle engineering,high-entropy material construction,and integrated modification are proposed.Finally,a summary and outlook provide a new horizon for developing and modifying layered oxide cathode materials.展开更多
目的:比较Fuji IX GP玻璃离子水门汀、3M ESPE Filtek^(TM) Bulk Fill Flowable树脂、VOCO Polofil Supra树脂及Beautiful Flow Plus F03树脂修复根面龋的临床疗效。方法:选取后牙根面龋患者128例(422颗患牙),按照充填修复材料分为A组(F...目的:比较Fuji IX GP玻璃离子水门汀、3M ESPE Filtek^(TM) Bulk Fill Flowable树脂、VOCO Polofil Supra树脂及Beautiful Flow Plus F03树脂修复根面龋的临床疗效。方法:选取后牙根面龋患者128例(422颗患牙),按照充填修复材料分为A组(Fuji IX GP玻璃离子水门汀修复)34例、B组(3M ESPE Filtek^(TM) Bulk Fill Flowable树脂修复)29例、C组(VOCO Polofil Supra树脂修复)35例、D组(Beautiful Flow Plus F03树脂修复)30例。手术治疗后随访6个月,比较4组患者牙髓活力、材料密合性、充填物表面磨损及充填物完好性情况。结果:术后6个月,4组患者牙髓活力均正常。A组、B组、C组、D组材料密合性好的患牙占比分别为75.49%、90.74%、88.57%、97.20%,A组低于B组、C组、D组,差异均有统计学意义(P<0.05);B组与D组、C组与D组比较,差异均有统计学意义(P<0.05),B、C组之间差异无统计学意义(P>0.05)。A组、B组、C组、D组充填物表面无磨损的患牙占比分别为77.45%、95.37%、94.29%、99.07%,A组占比低于B组、C组及D组,差异均有统计学意义(P<0.05);B组与C组、B组与D组、C组与D组间比较,差异均无统计学意义(P>0.05)。A组、B组、C组、D组充填物完好的患牙占比分别为91.18%、97.22%、97.14%、99.07%,A组占比低于D组,差异有统计学意义(P<0.05)。其他组之间比较,差异均无统计学意义(P>0.05)。结论:4种材料对牙髓活力均无影响,树脂类材料在密合性、表面磨损情况以及完好性上均优于Fuji IX GP玻璃离子水门汀。三种树脂类材料中Beautiful Flow Plus F03在密闭性方面优于其他两种树脂。展开更多
Two acetate-fed sequencing batch reactors （SBR） were operated under an aerobic dynamic feeding （ADF） model （SBR#2） and with anaerobic phase before aerobic phase （SBR#1） to select mixed cultures with a high pol...Two acetate-fed sequencing batch reactors （SBR） were operated under an aerobic dynamic feeding （ADF） model （SBR#2） and with anaerobic phase before aerobic phase （SBR#1） to select mixed cultures with a high polyhydroxyalkanoates （PHA） storage response. Although kinetic selection based on storage response should bring about a predominance of floc-formers, a bulking sludge with storage response comparable to well-settled sludge was steadily established. An anaerobic phase was introduced before the aerobic phase in the ADF model to improve the sludge settleability （SBR #1）, however, due to the consequent increased feast/famine ratio, the performance of SBR #1, in terms of both the maximum PHB （polyhydroxybutyrate） cell content and APHB, was lower than that of SBR #2. SBR #2 gradually reached a steady state while SBR #1 failed suddenly after 50 days of operation. The maximum specific substrate uptake rate and storage rate for the selected bulking sludge were 0.4 Cmol Ae/（Cmol X.hr） and 0.18 Cmol Ac/（Cmol PHB.hr）, respectively, resulting a yield of 0.45 Cmol PHB/（Cmol Ae） in SBR #2 in the culture enrichment phase. A maximum PHB content of 53% of total suspended solids and PHB storage rate of 1.36 Cmol Ac/（Cmol PHB.hr） was achieved at 10.2 hr in batch accumulation tests under nitrogen starvation. The results indicated that it was feasible to utilize filamentous bacteria to accumulate PHA with a rate comparable to well-settled sludge, Furthermore, the lower dissolved oxygen demand of filamentous bacteria would save energy required for aeration in the culture enrichment stage.展开更多
The bacterial community of a bulking sludge from a municipal wastewater treatment plant with anoxic-anaerobic-oxic process was investigated by combination of cultivation and 16S rRNA gene clone library analysis for un...The bacterial community of a bulking sludge from a municipal wastewater treatment plant with anoxic-anaerobic-oxic process was investigated by combination of cultivation and 16S rRNA gene clone library analysis for understanding the causes of bulking.A total of 28 species were obtained from 63 isolates collected from six culture media.The most cultivable species belonged to γ-Proteobacteria including Klebsiella sp.,Pseudomonas sp.,Aeromonas sp.and Acinetobacter sp.Further analysis of these strains by repetitive sequence based on polymerase chain reaction （rep-PCR） technology showed that rep-PCR yielded discriminatory banding patterns within the same genus using REP and BOX primer sets.While the culture-independent assessment revealed that β-Proteobacteria was the dominant group in the bulking sample.Sequence analysis revealed that the highest proportion （14.7%） of operational taxonomic units was 98% similar to Candidatus Accumulibacter phosphatis,which is used to remove phosphorous from wastewater.Our results indicated that combining different approaches can produce complementary information,thus generate a more accurate view of microbial community in bulking sludge.展开更多
The effects of adding a bulking agent on the performance and odor emissions（ammonia and eight sulfur-containing odorous compounds） when biodrying kitchen waste were investigated. Three treatments were considered： t...The effects of adding a bulking agent on the performance and odor emissions（ammonia and eight sulfur-containing odorous compounds） when biodrying kitchen waste were investigated. Three treatments were considered： the addition of either cornstalks（CS） or wood peat（WP） to kitchen waste as a bulking agent before biodrying, and a control treatment（CK）. The water-removal rates for CK, CS, and WP treatments were 0.35, 0.56, and0.43 kg/kg, respectively. Addition of bulking agents to kitchen waste produced less leachate,higher moisture-removal rates, and lower consumption of volatile solids. The CS treatment had the highest biodrying index（4.07）, and those for the WP and CK treatments were 3.67 and 1.97, respectively. Adding cornstalks or wood peat decreased NH3 emissions by 55.8%and 71.7%, respectively. Total sulfur losses were 3.6%–21.6% after 21 days biodrying, and H2 S and Me2 SS were the main（〉 95%） sulfur compounds released. The smallest amounts of sulfur-containing odorous compounds were emitted when cornstalks were added, and adding cornstalks and wood peat decreased total sulfur losses by 50.6%–64.8%.展开更多
Mismanagement of the composting process can result in emissions of CH4,N2O,and NH3,which have caused severe environmental problems.This study was aimed at determining whether CH4,N2O,and NH3 emissions from composting ...Mismanagement of the composting process can result in emissions of CH4,N2O,and NH3,which have caused severe environmental problems.This study was aimed at determining whether CH4,N2O,and NH3 emissions from composting are affected by bulking agents during rapid composting of pig manure from the Chinese Ganqinfen system.Three bulking agents,corn stalks,spent mushroom compost,and sawdust,were used in composting with pig manure in 60 L reactors with forced aeration for more than a month.Gas emissions were measured continuously,and detailed gas emission patterns were obtained.Concentrations of NH3 and N2O from the composting pig manure mixed with corn stalks or sawdust were higher than those from the spent mushroom compost treatment,especially the sawdust treatment,which had the highest total nitrogen loss among the three runs.Most of the nitrogen was lost in the form of NH3,which accounts for 11.16% to 35.69% of the initial nitrogen.One-way analysis of variance for NH3emission showed no significant differences between the corn stalk and sawdust treatments,but a significant difference was noted between the spent mushroom compost and sawdust treatments.The introduction of sawdust reduced CH4emission more than the corn stalks and spent mushroom compost.However,there were no significant differences among the three runs for total carbon loss.All treatments were matured after 30 d.展开更多
This laboratory research investigated a possible cause of filamentous bulking under low level of dissolved oxygen conditions （dissolved oxygen value in aerobic zone maintained between 0.6-0.8 mgO2 /L） in an airlift ...This laboratory research investigated a possible cause of filamentous bulking under low level of dissolved oxygen conditions （dissolved oxygen value in aerobic zone maintained between 0.6-0.8 mgO2 /L） in an airlift inner-circular anoxic-aerobic reactor. During the operating period, it was observed that low nitrate concentrations affected sludge volume index significantly. Unlike the existing hypothesis, the batch tests indicated that filamentous bacteria （mainly Thiothrix sp.） could store nitrate temporarily under carbon restricted conditions. When nitrate concentration was below 4 mg/L, low levels of carbon substrates and dissolved oxygen in the aerobic zone stimulated the nitrate-storing capacity of filaments. When filamentous bacteria riched in nitrate reached the anoxic zone, where they were exposed to high levels of carbon but limited nitrate, they underwent denitrification. However, when nonfilamentous bacteria were exposed to similar conditions, denitrification was restrained due to their intrinsic nitrate limitation. Hence, in order to avoid filamentous bulking, the nitrate concentration in the return sludge （from aerobic zone to the anoxic zone） should be above 4 mg/L, or alternatively, the nitrate load in the anoxic zone should be kept at levels above 2.7 mg NO-3N/g SS.展开更多
基金Supported by the National Natural Science Foundation of China(51208068)~~
文摘[Objective] This study aimed to make use of the limited filamentous sludge bulking characteristics to purify water quality and save energy. [Method] The effects of dissolved oxygen （DO） on sludge bulking were explored by changing the DO con- centration in the aerobiotic pool of NO system from the low load （0.25 kg COD/（kg MLSS.d）） and the medium to high load （0.55 kgCOD/（kg MLSSod））. [Result] In the NO activated sludge system, when the sludge load was 0.25 kg COD/（kg MLSS.d）, DO=1.5 mg/L, the sludge index was at around 250, while when the sludge load- ing was 0.55 kg COD/（kg MLSS.d）, DO=1.5 mg/L, the sludge index was close to 300, occurring the limited filamentous bulking. The bulked sludge still showed high removal rates to COD, SS, nitrogen and phosphorus. [Conclusion] It could improve the oxygen transfer rate and reduce the aeration rate at low DO conditions to achieve energy-saving.
基金Financial support for this work was obtained from the National Natural Science Foundation of China(No.51074059)
文摘The present study examines the results of the researches related to the gob bulking factor carried out at home and abroad.A mathematical function of a three-dimensional gob bulking factor is described based on a three-dimensional gob model.The method of taking value for interstice and permeability ratios is also proposed.The law of air leakage of fully mechanized top coal is researched in this study.The results show that the speed of air flow near the upper and lower crossheadings is higher than that in the central section of the gob at the same distance from the working face.When the amount of air at the working face exceeds a critical amount,the width of the spontaneous combustion zone in the upper and lower crossheadings is also larger than that in the central section.In this situation,the key is preventing the coal left in the upper and lower crossheadings from self-igniting.Reducing the amount of air at the working face can decrease the width of the spontaneous combustion zone,especially the width near the upper and lower crossheadings.This also moves the spontaneous combustion zone in the direction of the working face.It can prevent the coal in the gob from self-igniting by making the coal left in the crossheadings to be inert and by effectively controlling the amount of air at the working face.
基金Projects(50978087,50908081)supported by the National Natural Science Foundation of China
文摘Static aerobic composting of municipal sewage sludge with forced ventilation or air ventilation using matured compost as bulking conditioner was investigated. Physical and chemical parame ,eters, e.g., temperature, moisture content, VSS, CODcr, pH, and germination index （GI）, were analyzed to characterize the composting process. Fermentation starts quickly in both forced and air ventilation compost heaps and reaches high-temperature stage after 2 d, owing to the bulking function of matured compost. Compared to air ventilation, however, forced ventilation enables the high-temperature stage to last longer for approximately 7 d. The moisture content of both compost bodies decreases from 62% to about 50% as a result of evaporation, and it decreases slightly faster in forced ventilation compost heap after 13 d due to the higher temperature and better ventilation condition. Although no obvious differences of VSS and pH are observed between both compost heaps, the soluble CODcr and GI show differences during the second half period of fermentation. In forced ventilation compost, the soluble CODcr has a small rebound after 13 d, and GI decreases from 46% to 35% but then increases. These results show that in general, the matured compost is a good conditioner and force ventilation with a proper air supply strategy can be more efficient than air ventilation.
基金This work was supported by the National Natural Science Foundation of China,NSFC(Nos.U1803118 and 51974296)and the China Scholarship Council(CSC)(award to Fanfei Meng for PhD period at Kyushu University).
文摘Bulking characteristics of gangue are of great significance for the stability of goafs in mining overburden in the caving zones.In this paper,a particle discrete element method with clusters to represent gangue was adopted to explore the bulking coefficient time effect of the broken rock in the caving zone under three-dimensional triaxial compression condition.The phenomena of stress corrosion,deformation,and failure of rock blocks were simulated in the numerical model.Meanwhile,a new criterion of rock fragments damage was put forward.It was found that the broken rock has obvious viscoelastic properties.A new equation based on the Burgers creep model was proposed to predict the bulking coefficient of broken rock.A deformation characteristic parameter of the prediction equation was analyzed,which can be set as a fixed value in the mid-and long-term prediction of the bulking coefficient.There are quadratic function relationships between the deformation characteristic parameter value and Talbot gradation index,axial pressure and confining pressure.
基金the Key Scientific Research in Colleges and Universities of Henan Province Project(Grant No.20B560018)the National Science and Technology Major Project of the Ministry of Science and Technology of China(Grant No.2015ZX07204-002-04).
文摘Viscous sludge bulking is a rare phenomenon in activated sludge process.The performances of nutrients removal were investigated with normal sludge and viscous bulking sludge.The results showed that when COD loading and C/N ratio were around 0.13 mg COD/(mg MLSS·d)and 7.67,the effect of viscous sludge bulking on the maximum specific oxidation rates of NH_(4)^(+)⁃N was very little,while the maximum specific oxidation rates of NO_(2)^(-)⁃N decreased from 24.69 mg/(g·h)to 1.20 mg/(g·h).Compared with normal sludge,viscous bulking sludge had bigger particle size and more extracellular polymeric substances(EPS).The mass transfer resistance in sludge flocs might be the main cause of the difference in NO-2⁃N oxidation rates.Therefore,this study demonstrates that viscous sludge bulking is beneficial to enhance simultaneous nitrification and denitrification(SND),and excessive EPS will exhibit storage function during phosphorus removal process.
基金863 Program(2002AA601310) Heilongjiang Province Natural Science Fund (E0323)+1 种基金 Education Bureau Projects of HeilongjiangProvince (10541031) Science and Technology Projects of Heilongjiang Province (GB04B717- 06)
文摘Sludge bulking property of membrane bio-reactor was investigated in this study through contrast research. When the sludge bulking appeared, the removal efficiency of COD in membrane bio-reactor increased slightly through the function of filamentous bacteria. However, the negative effects of the higher net water-head differential pressures, the high block rate of membrane pore and the great quantity of filamentous bacteria at the external surface presented at the same time. Thus, plenty of methods should be performed to control sludge bulking once it happened in membrane bio-reactor.
基金Supported by 863 program ( No. 2002aa601310 )Harbin Municipal Science and Technology Commission (No.0014211038).
文摘Albumen wastewater was treated by Membrane Bio-reactor. Sludge bulking property of Membrane Bio-Reactor was investigated in this study through contrast research. When the sludge bulking appeared, the removal efficiency of COD in Membrane Bio-reactor increased slightly under the function of filamentous bacteria. However, the negative effects of the higher net water-head differential pressures,the higher block rate of membrane pore and the great quantity of filamentous bacteria at the externalsurface pres...
文摘Background: Urinary incontinence mainly affects women regardless of age and, as it affects their quality of life, influences work, sex life and independence for activities of daily living. The treatment of stress urinary incontinence including urethral volume injection therapy can provide an intermediate option over non-surgical and surgical therapies. One of the mechanisms for stress continence depends on the effective coaptation of the urethra during the increase in intra-abdominal pressure. The bulking agents can be injected transurethral or periurethral retrogradely, using direct vision from a cystoscope. Purpose: To evaluate the feasibility and preliminary outcome performance of the bacterial polysaccharide gel used as biological bulking agent applied in female patients with stress urinary incontinence. Methods: A prospective clinical pilot study was performed, in a single institution, including female patients who were admitted to the urologic outpatient clinic with Stress Urinary Incontinence (SUI) without previous treatments and they were selected and underwent bulking agent procedure. The evaluation was performed at the time of enrollment and 6 months after treatment. The primary outcome was Quality of Life (QOL) using the ICIQ-SF Questionnaire. The amount of urine leakage measured by the 1-HOUR PAD-TEST was the second outcome. Results: Fifteen women (with an average age of 53 years) were submitted to the application of bacterial cellulose gel and she was analyzed. Only two patients presented unchanged incontinence. The study considered as primary outcome the improvement or disappearance of symptoms after six months of intervention. Post-intervention Quality of Life (QOL) questionnaire indicated that all of these patients related a better quality of life (62.5%). Through the PAD-test it was possible to observe a decrease in urinary leak of 85% comparing the results pre and post-intervention (BCA—Bacterial Cellulose Application) with p-value equal to 0.000009. Conclusions: The results of this pilot study suggest that the use of biological bulking agent is a promising approach to treat stress urinary incontinence in female patients. Trial registration: Registration number and date of registration should be instated in this section.
文摘The use of hyaluronic acid and dextranomer (Solesta, Salix) injection in the anal canal is an emerging modal-ity in the treatment of fecal incontinence. However, little is known regarding the endoscopic and radiological appearance following injection of this ano-rectal bulking agent. We report computed tomography and endoscopic findings after hyaluronic acid/dextranomer injection in the ano-rectal area.
基金the National Natural Science Foundation of China(No.50275094).
文摘Based on the characteristics of 3D bulk forming process, the arbitrary Lagrangian-Eulerian (ALE) formulation-based FEM is studied, and a prediction-correction ALE-based FEM is proposed which integrates the advantages of precisely predicting the boundary configuration of the deformed material, and of efficiently avoiding hexahedron remeshing processes. The key idea of the prediction-correction ALE FEM is elaborated in detail. Accordingly, the strategy of mesh quality control, one of the key enabling techniques for the 3D bulk forming process numerical simulation by the prediction-correction ALE FEM is carefully investigated, and the algorithm for hexahedral element refinement is formulated based on the mesh distortion energy.
基金the National Natural Science Foundation of China(No.42377172)the National Key Research and Development Plan Project of China(No.2023YFC2907204).
文摘The Voronoi grain-based breakable block model(VGBBM)based on the combined finite-discrete element method(FDEM)was proposed to explicitly characterize the failure mechanism and predict the deformation behavior of hard-rock mine pillars.The influence of the microscopic parameters on the macroscopic mechanical behavior was investigated using laboratory-scale models.The field-scale pillar models(width-to-height,W/H=1,2 and 3)were calibrated based on the empirically predicted stress-strain curves of Creighton mine pillars.The results indicated that as the W/H ratios increased,the VGBBM effectively predicted the transition from strain-softening to pseudo-ductile behavior in pillars,and explicitly captured the separated rock slabs and the V-shaped damage zones on both sides of pillars and conjugate shear bands in core zones of pillars.The volumetric strain field revealed significant compressional deformation in core zones of pillars.While the peak strains of W/H=1 and 2 pillars were relatively consistent,there were significant differences in the strain energy storage and release mechanism.W/H was the primary factor influencing the deformation and strain energy in the pillar core.The friction coefficient of the structural plane was also an important factor affecting the pillar strength and the weakest discontinuity angle.The fracture surface was controlled by the discontinuity angle and the friction coefficient.This study demonstrated the capability of the VGBBM in predicting the strengths and deformation behavior of hard-rock pillars in deep mine design.
基金the Fundamental Research Funds for the Central Universities,China(No.06500177)the National Natural Science Foundation of China Joint Fund Project(No.U1764255)。
文摘Layered oxide is a promising cathode material for sodium-ion batteries because of its high-capacity,high operating voltage,and simple synthesis.Cycling performance is an important criterion for evaluating the application prospects of batteries.However,facing challenges,including phase transitions,ambient stability,side reactions,and irreversible anionic oxygen activity,the cycling performance of layered oxide cathode materials still cannot meet the application requirements.Therefore,this review proposes several strategies to address these challenges.First,bulk doping is introduced from three aspects:cationic single doping,anionic single doping,and multi-ion doping.Second,homogeneous surface coating and concentration gradient modification are reviewed.In addition,methods such as mixed structure design,particle engineering,high-entropy material construction,and integrated modification are proposed.Finally,a summary and outlook provide a new horizon for developing and modifying layered oxide cathode materials.
文摘目的:比较Fuji IX GP玻璃离子水门汀、3M ESPE Filtek^(TM) Bulk Fill Flowable树脂、VOCO Polofil Supra树脂及Beautiful Flow Plus F03树脂修复根面龋的临床疗效。方法:选取后牙根面龋患者128例(422颗患牙),按照充填修复材料分为A组(Fuji IX GP玻璃离子水门汀修复)34例、B组(3M ESPE Filtek^(TM) Bulk Fill Flowable树脂修复)29例、C组(VOCO Polofil Supra树脂修复)35例、D组(Beautiful Flow Plus F03树脂修复)30例。手术治疗后随访6个月,比较4组患者牙髓活力、材料密合性、充填物表面磨损及充填物完好性情况。结果:术后6个月,4组患者牙髓活力均正常。A组、B组、C组、D组材料密合性好的患牙占比分别为75.49%、90.74%、88.57%、97.20%,A组低于B组、C组、D组,差异均有统计学意义(P<0.05);B组与D组、C组与D组比较,差异均有统计学意义(P<0.05),B、C组之间差异无统计学意义(P>0.05)。A组、B组、C组、D组充填物表面无磨损的患牙占比分别为77.45%、95.37%、94.29%、99.07%,A组占比低于B组、C组及D组,差异均有统计学意义(P<0.05);B组与C组、B组与D组、C组与D组间比较,差异均无统计学意义(P>0.05)。A组、B组、C组、D组充填物完好的患牙占比分别为91.18%、97.22%、97.14%、99.07%,A组占比低于D组,差异有统计学意义(P<0.05)。其他组之间比较,差异均无统计学意义(P>0.05)。结论:4种材料对牙髓活力均无影响,树脂类材料在密合性、表面磨损情况以及完好性上均优于Fuji IX GP玻璃离子水门汀。三种树脂类材料中Beautiful Flow Plus F03在密闭性方面优于其他两种树脂。
基金support of the National Special S&T Project on the Treatment and Control of Water Pollution of China (No. 2008ZX07313-003)the Science Foundation of Harbin (No. 2007RFLXS013)+1 种基金the State Key Lab of Urban Water Resource and Environment at Harbin Institute of Technology (No. 2010DX02)the National Innovation Team supported by the National Science Foundation of China (No. 50821002)
文摘Two acetate-fed sequencing batch reactors （SBR） were operated under an aerobic dynamic feeding （ADF） model （SBR#2） and with anaerobic phase before aerobic phase （SBR#1） to select mixed cultures with a high polyhydroxyalkanoates （PHA） storage response. Although kinetic selection based on storage response should bring about a predominance of floc-formers, a bulking sludge with storage response comparable to well-settled sludge was steadily established. An anaerobic phase was introduced before the aerobic phase in the ADF model to improve the sludge settleability （SBR #1）, however, due to the consequent increased feast/famine ratio, the performance of SBR #1, in terms of both the maximum PHB （polyhydroxybutyrate） cell content and APHB, was lower than that of SBR #2. SBR #2 gradually reached a steady state while SBR #1 failed suddenly after 50 days of operation. The maximum specific substrate uptake rate and storage rate for the selected bulking sludge were 0.4 Cmol Ae/（Cmol X.hr） and 0.18 Cmol Ac/（Cmol PHB.hr）, respectively, resulting a yield of 0.45 Cmol PHB/（Cmol Ae） in SBR #2 in the culture enrichment phase. A maximum PHB content of 53% of total suspended solids and PHB storage rate of 1.36 Cmol Ac/（Cmol PHB.hr） was achieved at 10.2 hr in batch accumulation tests under nitrogen starvation. The results indicated that it was feasible to utilize filamentous bacteria to accumulate PHA with a rate comparable to well-settled sludge, Furthermore, the lower dissolved oxygen demand of filamentous bacteria would save energy required for aeration in the culture enrichment stage.
基金supported by the"Knowledge In-novation"Program of Chinese Academy of Sciences(No.KZCX2-YW-JC407-3,KSCX2-YW-G-054-2)the Ministry of Science and Technology,China(No.2006DFA91870)
文摘The bacterial community of a bulking sludge from a municipal wastewater treatment plant with anoxic-anaerobic-oxic process was investigated by combination of cultivation and 16S rRNA gene clone library analysis for understanding the causes of bulking.A total of 28 species were obtained from 63 isolates collected from six culture media.The most cultivable species belonged to γ-Proteobacteria including Klebsiella sp.,Pseudomonas sp.,Aeromonas sp.and Acinetobacter sp.Further analysis of these strains by repetitive sequence based on polymerase chain reaction （rep-PCR） technology showed that rep-PCR yielded discriminatory banding patterns within the same genus using REP and BOX primer sets.While the culture-independent assessment revealed that β-Proteobacteria was the dominant group in the bulking sample.Sequence analysis revealed that the highest proportion （14.7%） of operational taxonomic units was 98% similar to Candidatus Accumulibacter phosphatis,which is used to remove phosphorous from wastewater.Our results indicated that combining different approaches can produce complementary information,thus generate a more accurate view of microbial community in bulking sludge.
基金financially supported by the Ministry of Science and Technology of the People's Republic of Chinathrough the High Effective Intelligent Composting Process and Key Technology Research program(No.2016YFD0800601)the project of“State Key Laboratory of Solid Waste Reuse for Building Materials”(No.SWR-2014-005)
文摘The effects of adding a bulking agent on the performance and odor emissions（ammonia and eight sulfur-containing odorous compounds） when biodrying kitchen waste were investigated. Three treatments were considered： the addition of either cornstalks（CS） or wood peat（WP） to kitchen waste as a bulking agent before biodrying, and a control treatment（CK）. The water-removal rates for CK, CS, and WP treatments were 0.35, 0.56, and0.43 kg/kg, respectively. Addition of bulking agents to kitchen waste produced less leachate,higher moisture-removal rates, and lower consumption of volatile solids. The CS treatment had the highest biodrying index（4.07）, and those for the WP and CK treatments were 3.67 and 1.97, respectively. Adding cornstalks or wood peat decreased NH3 emissions by 55.8%and 71.7%, respectively. Total sulfur losses were 3.6%–21.6% after 21 days biodrying, and H2 S and Me2 SS were the main（〉 95%） sulfur compounds released. The smallest amounts of sulfur-containing odorous compounds were emitted when cornstalks were added, and adding cornstalks and wood peat decreased total sulfur losses by 50.6%–64.8%.
基金supported by the National Natural Science Foundation of China(Nos.41275161 and 41075110)the National Science&Technology Pillar Program(Nos.2012BAD14B01 and 2012BAD14B03)+1 种基金the Sino-German Cooperation Project of Recycling of Organic Residues from Agricultural and Municipal Residues in China(No.BMBF FKZ 0330847)the Chinese Universities Scientific Fund
文摘Mismanagement of the composting process can result in emissions of CH4,N2O,and NH3,which have caused severe environmental problems.This study was aimed at determining whether CH4,N2O,and NH3 emissions from composting are affected by bulking agents during rapid composting of pig manure from the Chinese Ganqinfen system.Three bulking agents,corn stalks,spent mushroom compost,and sawdust,were used in composting with pig manure in 60 L reactors with forced aeration for more than a month.Gas emissions were measured continuously,and detailed gas emission patterns were obtained.Concentrations of NH3 and N2O from the composting pig manure mixed with corn stalks or sawdust were higher than those from the spent mushroom compost treatment,especially the sawdust treatment,which had the highest total nitrogen loss among the three runs.Most of the nitrogen was lost in the form of NH3,which accounts for 11.16% to 35.69% of the initial nitrogen.One-way analysis of variance for NH3emission showed no significant differences between the corn stalk and sawdust treatments,but a significant difference was noted between the spent mushroom compost and sawdust treatments.The introduction of sawdust reduced CH4emission more than the corn stalks and spent mushroom compost.However,there were no significant differences among the three runs for total carbon loss.All treatments were matured after 30 d.
基金supported by the National Natural Science Foundation of China (No. 51138009, 41072172)the National Key Technology R&D Program (No. 2012BAJ25B04)+1 种基金the Program for New Century Excellent Talents in University (No. NCET-11-0391)the Project of Shanghai Science and Technology Commision (No. 11QH1402600)
文摘This laboratory research investigated a possible cause of filamentous bulking under low level of dissolved oxygen conditions （dissolved oxygen value in aerobic zone maintained between 0.6-0.8 mgO2 /L） in an airlift inner-circular anoxic-aerobic reactor. During the operating period, it was observed that low nitrate concentrations affected sludge volume index significantly. Unlike the existing hypothesis, the batch tests indicated that filamentous bacteria （mainly Thiothrix sp.） could store nitrate temporarily under carbon restricted conditions. When nitrate concentration was below 4 mg/L, low levels of carbon substrates and dissolved oxygen in the aerobic zone stimulated the nitrate-storing capacity of filaments. When filamentous bacteria riched in nitrate reached the anoxic zone, where they were exposed to high levels of carbon but limited nitrate, they underwent denitrification. However, when nonfilamentous bacteria were exposed to similar conditions, denitrification was restrained due to their intrinsic nitrate limitation. Hence, in order to avoid filamentous bulking, the nitrate concentration in the return sludge （from aerobic zone to the anoxic zone） should be above 4 mg/L, or alternatively, the nitrate load in the anoxic zone should be kept at levels above 2.7 mg NO-3N/g SS.
