Due to a prolonged operation time and low mass transfer efficiency, the primary challenge in the aeration process of non-Newtonian fluids is the high energy consumption, which is closely related to the form and rate o...Due to a prolonged operation time and low mass transfer efficiency, the primary challenge in the aeration process of non-Newtonian fluids is the high energy consumption, which is closely related to the form and rate of impeller, ventilation, rheological properties and bubble morphology in the reactor. In this perspective, through optimal computational fluid dynamics models and experiments, the relationship between power consumption, volumetric mass transfer rate(kLa) and initial bubble size(d0) was constructed to establish an efficient operation mode for the aeration process of non-Newtonian fluids. It was found that reducing the d0could significantly increase the oxygen mass transfer rate, resulting in an obvious decrease in the ventilation volume and impeller speed. When d0was regulated within 2-5 mm,an optimal kLa could be achieved, and 21% of power consumption could be saved, compared to the case of bubbles with a diameter of 10 mm.展开更多
Landfilled organic waste, in the presence of oxygen, can undergo aerobic decomposition facilitated by heterotrophic microorganisms. Aerobic degradation of solid waste can quickly consume available oxygen thus curtaili...Landfilled organic waste, in the presence of oxygen, can undergo aerobic decomposition facilitated by heterotrophic microorganisms. Aerobic degradation of solid waste can quickly consume available oxygen thus curtailing further degradation. The aim of this study was the investigation of a low-cost method of replenishing oxygen consumed in landfilled waste. Three 2D lysimeters were established to investigate the effectiveness of stand-alone, vertical ventilation pipes inserted into waste masses. Two different configurations of ventilation were tested with the third lysimeter acting as an unventilated control. Lysimeters were left uninsulated and observed over the course of 6 months with regular collection of gas and leachate samples. Lysimeters were then simulated for Oxygen (O<sub>2</sub>) and Nitrous oxide (N<sub>2</sub>O) to analyze the denitrification contributions of each. The experiment revealed that a single ventilation pipe can increase the mean oxygen level of a 1.7 m × 1.0 m area by up to 13.5%. It also identified that while increasing the density of ventilation pipes led to increased O<sub>2</sub> levels, this increase was not significant at the 0.05 probability level. A single vent averaged 13.67% O<sub>2</sub> while inclusion of an additional vent in the same area only increased the average to 14.59%, a 6.7% increase. Simulation helped to verify that lower ventilation pipe placement density may be more efficient as in addition to the effect on oxygenation, denitrification efficiency may increase. Simulations of N<sub>2</sub>O production estimated between 8% - 20% more N<sub>2</sub>O being generated with lower venting density configurations.展开更多
The Chicago Area Waterway System(CAWS)is a 133.9 km branching network of navigable waterways controlled by hydraulic structures,in which the majority of the flow is treated wastewater effluent and there are periods of...The Chicago Area Waterway System(CAWS)is a 133.9 km branching network of navigable waterways controlled by hydraulic structures,in which the majority of the flow is treated wastewater effluent and there are periods of substantial combined sewer overflows.The CAWS comprises a network of effluent dominated streams.More stringent dissolved oxygen(DO)standards and a reduced flow augmentation allowance have been recently applied to the CAWS.Therefore,a carefully calibrated and verified one-dimensional flow and water quality model was applied to the CAWS to determine emission-based real-time control guidelines for the operation of flow augmentation and aeration stations.The goal of these guidelines was to attain DO standards at least 95%of the time.The“optimal”guidelines were tested for representative normal,dry,and wet years.The finally proposed guidelines were found in the simulations to attain the 95%target for nearly all locations in the CAWS for the three test years.The developed operational guidelines have been applied since 2018 and have shown improved attainment of the DO standards throughout the CAWS while at the same time achieving similar energy use at the aeration stations on the Calumet River system,greatly lowered energy use on the Chicago River system,and greatly lowered discretionary diversion from Lake Michigan,meeting the recently enacted lower amount of allowed annual discretionary diversion.This case study indicates that emission-based real-time control developed from a well calibrated model holds potential to help many receiving water bodies achieve high attainment of water quality standards.展开更多
The effects of aeration rates and aeration patterns on the oxidation of ammonia-nitrogen into nitrite were investigated. The influent high ammonia-nitrogen synthetic wastewater resembled to those of the catalytic proc...The effects of aeration rates and aeration patterns on the oxidation of ammonia-nitrogen into nitrite were investigated. The influent high ammonia-nitrogen synthetic wastewater resembled to those of the catalytic process of the petrochemical refinery. The method involved the biological shortcut nitrification and denitrification lab-scale’s sequencing batch reactor (SBR) process based on intermittent aerations and aeration patterns. All the operations were carried out in a 20 L working volume SBR bioreactor, and the influent synthetic wastewater’s concentration was always 1000 mg/L ammonia-nitrogen NH<sub>4</sub>-N concentration at a C/N (carbon/nitrogen) ratio of 2.5:1. Effective shortcut nitrification to nitrite was registered at 1.1 mg-O<sub>2</sub>/L (i.e. 9 L-air/min) with 99.1% nitrification efficiency, 99.0% nitritation rate and 2.6 mg-NO<sub>3</sub>-</sup>-N/L nitrate concentration. The best results with 99.3% nitrification efficiency were recorded when operating at 1.4 mg-O<sub>2</sub>/L (i.e. 12 L-air/min). According to these experiments, it results that the nitrite accumulation rate was related to aeration rate and cycle’s duration. However, at 1.7 mg-O<sub>2</sub>/L (i.e. 15 L-air/min), the system was limited by an increase in nitrate concentration with more than 5 mg/L which could be a point of reverse to conventional nitrification. The best total nitrogen (TN) removal was about 71.5%.展开更多
In order to clarify the effects of aeration on root nitrogen metabolism in rice seedlings,rice cultivars Guodao 6 (indica) and Xiushui 09 (japonica) were investigated for root growth,the activities of glutamine synthe...In order to clarify the effects of aeration on root nitrogen metabolism in rice seedlings,rice cultivars Guodao 6 (indica) and Xiushui 09 (japonica) were investigated for root growth,the activities of glutamine synthetase (GS),glutamic acid-pyruvic acid transaminase (GPT) and glutamic acid oxaloacetate transaminase (GOT),the nitrate (NO 3-N) concertration,the contents of free amino acids and soluble sugar in root under hydroponics with continuous aeration treatment.The results showed that rice seedlings grown in oxygenation solutions had higher root dry matter,longer root length,stronger root activity and larger root absorption area compared with the control.In addition,the contents of soluble sugar,root vigor and the activities of GS,GOT and GPT in the aeration solutions were higher than those in the control.The results also indicated that the activities of enzymes involved in root nitrogen metabolism of Xiushui 09 were enhanced by aeration,however,there was no significant influence on root nitrogen metabolism of Guodao 6,which suggested that effect of oxygenation on rice root nitrogen metabolism might be genotype-specific.展开更多
Despite lots of techniques in improving the heap leaching performance,many constraints on the industrial applications remain.We proposed a correspondingly effective and new idea of introducing forced aeration to impro...Despite lots of techniques in improving the heap leaching performance,many constraints on the industrial applications remain.We proposed a correspondingly effective and new idea of introducing forced aeration to improve the bad permeability and leaching effect of Yangla Copper Mine(YCM)during heap leaching.The dual-media theory was employed to study the impact mechanism of forced aeration on the variations of porous and fractured media during the column leaching experiments.An X-Ray Computed Tomography(CT)set was utilized to perform the pore imaging of the specimens and the fracture morphology of the particles within the columns was analyzed by Scanning Electron Microscope(SEM)as aeration rate(AR)changed.The results show that there exists copious fine particles within the heap of YCM,the particle size distribution of which is not reasonable.The forced aeration can not only promote the development of the porous and fractured structures but effectively break the blocked seepage paths.Then the leaching degree is improved and the seepage performance of the solute within the solution is enhanced.Therefore,the forced aeration is probable of making the leaching performance greatly improved.展开更多
Bacterial community dynamics and copper leaching with applied forced aeration were investigated during low-grade copper sulphide bioleaching to obtain better bioleaching efficiency.Results illustrated that appropriate...Bacterial community dynamics and copper leaching with applied forced aeration were investigated during low-grade copper sulphide bioleaching to obtain better bioleaching efficiency.Results illustrated that appropriate aeration improved bacterial concentrations and leaching efficiencies.The highest bacterial concentration and Cu^(2+)concentration after 14-d leaching were 7.61×10^(7) cells·mL^(−1) and 704.9 mg·L^(−1),respectively,at aeration duration of 4 h·d^(−1).The attached bacteria played a significant role during bioleaching from 1 to 7 d.However,free bacteria dominated the bioleaching processes from 8 to 14 d.This phenomenon was mainly caused by the formation of passivation layer through Fe3+hydrolysis along with bioleaching,which inhibited the contact between the attached bacteria and ore.Meanwhile,16S rDNA analysis verified the effect of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans on the bioleaching process.The results demonstrate the importance of free and attached bacteria in bioleaching.展开更多
In order to develop an effective MIBK removal method of H 2TaF 7 solution in tantalum extraction process, MIBK removal from aqueous solution by the aeration method was investigated by using an aeration column with the...In order to develop an effective MIBK removal method of H 2TaF 7 solution in tantalum extraction process, MIBK removal from aqueous solution by the aeration method was investigated by using an aeration column with the dimensions of 78 mm in inner diameter and 1 100 mm in length. The effects of aeration conditions on aerating efficiency were investigated in the ranges of temperature 303 333 K, airflow rate 50 300 L/h,volume of solution 1 600 3 200 mL. Aerating efficiency increases with the increase of temperature and airflow rate. MIBK in aqueous solution can be removed from 0.058 mol/L to 0.002 mol/L at 50 ℃,airflow rate 200 L/h, volume of solution 2 400 mL and aeration time 1h. The experimental results show that MIBK can be removed effectively from aqueous solution by the aeration method.展开更多
To improve the efficiency of ethanol production in a batch fermentation from sweet sorghum juice under a very high gravity(VHG)condition(~290 g/L of total sugar)by Saccharomyces cerevisiae NP01,repeatedbatch fermentat...To improve the efficiency of ethanol production in a batch fermentation from sweet sorghum juice under a very high gravity(VHG)condition(~290 g/L of total sugar)by Saccharomyces cerevisiae NP01,repeatedbatch fermentation under an aerated condition(2.5 vvm for the first 4 h during every cycle)was done in a5-L fermenter.The average ethanol concentration(P),productivity(Qp)and yield(Yp/s)for five successive cycles were 112.31 g/L,1.55 g/L·h^-1 and 0.44,respectively with 80.97%sugar consumption.To complete sugar consumption,the total sugar of the juice was reduced to a high gravity(HG)level(~240 g/L).The results showed that yeast extract was not necessary for ethanol production,and aeration during every other cycle i.e.,alternating cycles,was sufficient to promote both yeast growth and ethanol production.The average P,Qpand Yp/svalues for eight successive cycles with aeration during alternating cycles were97.58 g/L,1.98 g/Láh and 0.41,respectively with 91.21%sugar consumption.The total fatty acids in the yeast cells under the aerated condition were^50%higher than without aeration,irrespective the initial sugar concentration,whereas the ergosterol contents under aeration condition were^29%to 49%higher than those without aeration.展开更多
The effects of soil aeration on physiological characters and root tuber yield of Ipomoea batatas (L.) Lam. CV Lushu7 and Xushu18 were studied. The results showed that soil aeration improvement could increase ATP conte...The effects of soil aeration on physiological characters and root tuber yield of Ipomoea batatas (L.) Lam. CV Lushu7 and Xushu18 were studied. The results showed that soil aeration improvement could increase ATP content and ATPase activity in functional leaves and root tubers and ABA content in root tubers.It also accelerated the transportation of 14C-photosynthate from leaves to root tubers and enhanced dry matter distribution in root tubers and thus root tuber yield was significantly raised. The role of ATP, ATPase and ABA in accelerating the transportation of 14C-photosynthate was discussed based on the changes of soluble carbonhydrate content in sweet potato plant.展开更多
Different cadmium(Cd)-accumulated rice genotypes(Erjiunan 1 and Fupin 36)were used to explore the effect of rice rhizosphere aeration on Cd uptake and accumulation.Aeration in the nutrient soluti on influe need the ag...Different cadmium(Cd)-accumulated rice genotypes(Erjiunan 1 and Fupin 36)were used to explore the effect of rice rhizosphere aeration on Cd uptake and accumulation.Aeration in the nutrient soluti on influe need the agronomic characteristics in duced by Cd-stress,such as the in creases of rice root length and root vigor,but the reductions of plant height and shoot dry weight.Aeration also alleviated the decreasing effects of Cd stress on antioxidant enzyme activities and soluble protein,malonaldehyde and nicotianamine contents in rice.Moreover,with aeration treatment,the accumulation and bioavailability of metal elements changed significantly,with a Cd increase and an Fe reduction in both rice genotypes.In addition,at the molecular level,aeration upregulated the expression of Fe-inducible genes(such as OsIRTI,OsNRAMPI,OsYSL15 and OsNAS3).Furthermore,as a Cd^(2+)/Fe^(2+) transporter,the high transcription level of OsNRAMPI can elevate the Cd uptake and translocation in rice due to the Fe reduction caused by aeration and Cd-exposure,which indicated that OsNRAMPI might play a crucial role in the effect of aeration on Cd uptake and accumulation.展开更多
Aeration is an important measure to prevent cyanobacterial growth in eutrophic lakes and reservoirs.The purpose of this study is to clarify the infl uence of aeration induced turbulence on growth and competition of Mi...Aeration is an important measure to prevent cyanobacterial growth in eutrophic lakes and reservoirs.The purpose of this study is to clarify the infl uence of aeration induced turbulence on growth and competition of Microcystis and Scenedesmus in the presence of sediments with varying particle sizes.Microcystis aeruginosa and Scenedesmus obliquus were selected as the model organisms.Sediments with varying particle sizes were added into mono and mixed cultures of the organisms.In the absence of sediment,both low-and high-intensity aerations(the turbulent dissipation rates were 1.60×10^(-6)and 1.16×10^(-5)m^(2)/s^(3),respectively)promoted the growth of Scenedesmus,but the growth of Microcystis was inhibited particularly obvious under the high-intensity aeration conditions.In the presence of sediment,Scenedesmus was promoted under all aeration conditions,while Microcystis was inhibited.The inhibition rate of Microcystis decreased with the increase of sediment size when treated with low-intensity aeration in the nighttime.The highest inhibition rate of M.aeruginosa(89.2%)was identifi ed under the condition of low-intensity aeration in the nighttime with small sediment addition.Furthermore,our results indicated that the impacts of sediment-induced light intensity reduction on algal growth were insignifi cant.In the mixed culture,the growth of Microcystis was inhibited by Scenedesmus in all treatments with aeration.Our results provided a theoretical basis for the practice in controlling cyanobacteria by aeration.展开更多
Recently a research team at Ohio University,USA,conducted a unique full-scale feld load test to simulate the aeration pipe installations at a copper extraction mine operated in Chile.The overliner material taken from ...Recently a research team at Ohio University,USA,conducted a unique full-scale feld load test to simulate the aeration pipe installations at a copper extraction mine operated in Chile.The overliner material taken from the mine was used in recreating the in situ conditions.Electric heaters were utilized to raise the temperature inside each pipe to simulate the essential element of the copper extraction process.The maximum vertical deflection reached by the test pipes was close to 20%,when the simulated heap pile height was 80 m.The plastic pipes and the overliner material were also tested in the laboratory.Based on the results,the maximum heap pile fll depth was recommended for the aeration system.The results indicated that the vertical deflection was the primary performance index for the aeration pipes installed in heap piles at mines.Lastly,the pipe made of polypropylene resin was super.展开更多
In order to accelerate the consolidation of the dredged sludge and look for an effective material for mud-water separation,the study on the comparison of geotextiles is carried on. It is based on the laboratory model ...In order to accelerate the consolidation of the dredged sludge and look for an effective material for mud-water separation,the study on the comparison of geotextiles is carried on. It is based on the laboratory model test of aeration vacuum rapid mud- water separating( AVMWS) technique and evaluated by the cumulative weight of pumping water,the decrease of moisture content and the stable pumping speed. The results show that woven fabric is the best anti- clogging aeration vacuum material,followed by machine-woven fabric and non-woven fabric is the worst. The analysis has been proposed from two aspects of geotextile weaving technology and aeration vacuum condition.展开更多
With autotrophic microalgae cultivation,?we can feed back the CO2?content of process streams and we can get lots of valuable organic compounds, among others biofuel components. For the production of energy source,we m...With autotrophic microalgae cultivation,?we can feed back the CO2?content of process streams and we can get lots of valuable organic compounds, among others biofuel components. For the production of energy source,we must reckon with the energy balance of the whole process. Densification and processing of microalgae can consume 50% - 70% of the energy that can be extracted from the cells,?therefore the cultivation should use such a little energy as it possible. In closed cultivation systems,?there are three main energy intensive steps: artificial illumination, dissolution of gas compounds and mixing. We have carried out our measurements in our lab-scale screening photobioreactor system for the investigation of the most energy effective program for aeration. We have found the aeration program considerable solution for lower energy consumption in?algae cultivation.展开更多
A membrane bioreactor(MBR)with ordinary aeration(reactor R1)and a MBR with microporous aeration(reactor R2)are conducted in parallel to investigate the characteristics of oily sludge and its effect on membrane fouling...A membrane bioreactor(MBR)with ordinary aeration(reactor R1)and a MBR with microporous aeration(reactor R2)are conducted in parallel to investigate the characteristics of oily sludge and its effect on membrane fouling.The results indicate that the order of membrane fouling rate from high to low is:reactor R1 dissolved oxygen(DO)(1 mg/L)>reactor R2 DO(1 mg/L)>reactor R1 DO(4 mg/L)>reactor R2 DO(4 mg/L).Membrane fouling rate is not related to oily sludge concentration but to oily sludge sedimentation performance and the small particle oily sludge is the key factor to affect the membrane fouling.The soluble microbial products(SMP)are examined by three-dimensional excitation-emission matrix(3DEEM)fluorescence spectra.3DEEM spectra demonstrate that the main organic substances of the SMP in two reactors are tyrosine aromatic protein,fulvic acid-like substances and soluble microbial products under DO are1 mg/L and 4 mg/L,respectively.The proportion sum of fulvic acid-like substances and soluble microbial products is the key factor affecting membrane fouling,and membrane fouling accelerates as the ratio increases.展开更多
In the present study, the yeast Rhodotorula glutinis has been assessed with the aim of producing microbial lipids from glycerol under different aeration conditions. For such a purpose, experiments were carried out in ...In the present study, the yeast Rhodotorula glutinis has been assessed with the aim of producing microbial lipids from glycerol under different aeration conditions. For such a purpose, experiments were carried out in shake flasks, under different conditions of agitation (150 to 250 rpm) and aeration (2.5 to 5.0 of flask volume-to-medium volume ratio). Furthermore, their influence on fermentative parameters (lipid and cell concentration, biomass yield;lipid yield;and lipid volumetric productivity) has been investigated using a 22 full factorial design. The statistical analysis has revealed a strong influence of both variables on substrate consumption, lipid accumulation, cell growth and lipid productivity. As a whole, results suggest that higher aeration levels provide greater cell and lipid concentrations, and lipid volumetric productivity. The best results (4.5 g/L of lipids and QP = 0.95 g/L⋅day) were achieved at the highest aeration (5.0 flask volume-to-medium volume ratio) and agitation (250 rpm) levels. Their fatty acid profile showed that oleic acid was produced in greater quantity (53.5%), followed by linoleic acid (18.7%), palmitic acid (6.8%) and stearic acid (9.9%). The microbial oil presented viscosity of 39.3 cP at 50°C and free fatty acid content of 1.93% ± 0.08%. These are significant results and contribute to establishing operational conditions that maximize single-cell oil production from glycerol by Rhodotorula glutinis, i.e. an alternative source as renewable raw material for lipid-based biorefineries.展开更多
The aim of this work was the determination of the optimal aerations, and more specifically the corresponding optimal air velocities uopt, at which the largest COD removals were achieved in treatment of industrial wast...The aim of this work was the determination of the optimal aerations, and more specifically the corresponding optimal air velocities uopt, at which the largest COD removals were achieved in treatment of industrial wastewaters of various strength conducted in the inverse fluidized bed biofilm reactor. The largest COD removals were achieved at the following air velocities uopt and retention times ts, and (Vb/VR) = 0.55: i) for CODo = 72,780 mg/l at uopt = 0.052 m/s and ts = 80 h;ii) for CODo = 62,070 mg/l at uopt = 0.042 m/s and ts = 65 h;iii) for CODo = 49,130 mg/l at uopt = 0.033 m/s and ts= 55 h;iv) for CODo = 41,170 mg/l at uopt = 0.028 m/s and ts = 45 h;v) for CODo = 35,460 mg/l at uopt = 0.025 m/s and ts = 27.5 h;and vi) for CODo = 26,470 mg/l at uopt= 0.014 m/s and ts = 22.5 h. In the treatment operation conducted in a reactor optimally controlled at the above values of uopt, ts and (Vb/VR), the following decreases in COD were obtained: i) from 72,780 to 5410 mg/l;ii) from 62,070 to 3730 mg/l;iii) from 49,130 to 2820 mg/l;iv) from 41,170 to 1820 mg/l;v) from 35,460 to 1600 mg/l;and vi) from 26,470 to 1180 mg/l, that is, approximately a 93%, 94%, 95%, 96%, 95% and 96% COD reduction was attained, respectively.展开更多
In order to protect quality of Baiyangdian surface water and Gaoyang groundwater,the project is applied to process printing and dyeing wastewater that contains complicated compositions,high concentrations of organics ...In order to protect quality of Baiyangdian surface water and Gaoyang groundwater,the project is applied to process printing and dyeing wastewater that contains complicated compositions,high concentrations of organics and SS,and lots of pollutants difficult to degrade by microorganism. The process and operating parameters of project are optimized and debugged,and its economic and environmental benefits are analyzed.The results show that the process of coagulation sedimentation-hydrolytic acidification with aeration tank-biological aerated filter-active sand filter is applied in Gaoyang Sewage Treatment Plant. The design scale of sewage treatment plant is 120000 m^3/d. The influent is as following: COD is 669mg/L; SS is 424mg/L; NH_3-N is 8.83mg/L; TP is 6.03mg/L. After the process,the best removal rates of COD,SS,NH_3-N and TP are 93. 5%,98. 8%,97. 1% and 96. 2%,respectively. The various indexes of effluent water complied with standard A of the first order in Pollutants Emission Standard of Urban Wastewater Treatment Plant( GB 18918-2002). The processing cost is only 0. 807 yuan/m^3. As a result,the project construction and operation not only improve the environment,but also promote regional economic development. Process design and operating parameters provide an important reference value for the printing and dyeing wastewater treatment industry.展开更多
基金financial support of the National Natural Science Foundation of China(21776122).
文摘Due to a prolonged operation time and low mass transfer efficiency, the primary challenge in the aeration process of non-Newtonian fluids is the high energy consumption, which is closely related to the form and rate of impeller, ventilation, rheological properties and bubble morphology in the reactor. In this perspective, through optimal computational fluid dynamics models and experiments, the relationship between power consumption, volumetric mass transfer rate(kLa) and initial bubble size(d0) was constructed to establish an efficient operation mode for the aeration process of non-Newtonian fluids. It was found that reducing the d0could significantly increase the oxygen mass transfer rate, resulting in an obvious decrease in the ventilation volume and impeller speed. When d0was regulated within 2-5 mm,an optimal kLa could be achieved, and 21% of power consumption could be saved, compared to the case of bubbles with a diameter of 10 mm.
文摘Landfilled organic waste, in the presence of oxygen, can undergo aerobic decomposition facilitated by heterotrophic microorganisms. Aerobic degradation of solid waste can quickly consume available oxygen thus curtailing further degradation. The aim of this study was the investigation of a low-cost method of replenishing oxygen consumed in landfilled waste. Three 2D lysimeters were established to investigate the effectiveness of stand-alone, vertical ventilation pipes inserted into waste masses. Two different configurations of ventilation were tested with the third lysimeter acting as an unventilated control. Lysimeters were left uninsulated and observed over the course of 6 months with regular collection of gas and leachate samples. Lysimeters were then simulated for Oxygen (O<sub>2</sub>) and Nitrous oxide (N<sub>2</sub>O) to analyze the denitrification contributions of each. The experiment revealed that a single ventilation pipe can increase the mean oxygen level of a 1.7 m × 1.0 m area by up to 13.5%. It also identified that while increasing the density of ventilation pipes led to increased O<sub>2</sub> levels, this increase was not significant at the 0.05 probability level. A single vent averaged 13.67% O<sub>2</sub> while inclusion of an additional vent in the same area only increased the average to 14.59%, a 6.7% increase. Simulation helped to verify that lower ventilation pipe placement density may be more efficient as in addition to the effect on oxygenation, denitrification efficiency may increase. Simulations of N<sub>2</sub>O production estimated between 8% - 20% more N<sub>2</sub>O being generated with lower venting density configurations.
基金supported by the Metropolitan Water Reclamation District of Greater Chicago(Requisition No.1449764).
文摘The Chicago Area Waterway System(CAWS)is a 133.9 km branching network of navigable waterways controlled by hydraulic structures,in which the majority of the flow is treated wastewater effluent and there are periods of substantial combined sewer overflows.The CAWS comprises a network of effluent dominated streams.More stringent dissolved oxygen(DO)standards and a reduced flow augmentation allowance have been recently applied to the CAWS.Therefore,a carefully calibrated and verified one-dimensional flow and water quality model was applied to the CAWS to determine emission-based real-time control guidelines for the operation of flow augmentation and aeration stations.The goal of these guidelines was to attain DO standards at least 95%of the time.The“optimal”guidelines were tested for representative normal,dry,and wet years.The finally proposed guidelines were found in the simulations to attain the 95%target for nearly all locations in the CAWS for the three test years.The developed operational guidelines have been applied since 2018 and have shown improved attainment of the DO standards throughout the CAWS while at the same time achieving similar energy use at the aeration stations on the Calumet River system,greatly lowered energy use on the Chicago River system,and greatly lowered discretionary diversion from Lake Michigan,meeting the recently enacted lower amount of allowed annual discretionary diversion.This case study indicates that emission-based real-time control developed from a well calibrated model holds potential to help many receiving water bodies achieve high attainment of water quality standards.
文摘The effects of aeration rates and aeration patterns on the oxidation of ammonia-nitrogen into nitrite were investigated. The influent high ammonia-nitrogen synthetic wastewater resembled to those of the catalytic process of the petrochemical refinery. The method involved the biological shortcut nitrification and denitrification lab-scale’s sequencing batch reactor (SBR) process based on intermittent aerations and aeration patterns. All the operations were carried out in a 20 L working volume SBR bioreactor, and the influent synthetic wastewater’s concentration was always 1000 mg/L ammonia-nitrogen NH<sub>4</sub>-N concentration at a C/N (carbon/nitrogen) ratio of 2.5:1. Effective shortcut nitrification to nitrite was registered at 1.1 mg-O<sub>2</sub>/L (i.e. 9 L-air/min) with 99.1% nitrification efficiency, 99.0% nitritation rate and 2.6 mg-NO<sub>3</sub>-</sup>-N/L nitrate concentration. The best results with 99.3% nitrification efficiency were recorded when operating at 1.4 mg-O<sub>2</sub>/L (i.e. 12 L-air/min). According to these experiments, it results that the nitrite accumulation rate was related to aeration rate and cycle’s duration. However, at 1.7 mg-O<sub>2</sub>/L (i.e. 15 L-air/min), the system was limited by an increase in nitrate concentration with more than 5 mg/L which could be a point of reverse to conventional nitrification. The best total nitrogen (TN) removal was about 71.5%.
基金supported by the Provincial Natural Science Foundation of Zhejiang (Grant No. Y3100270)the Twelfth Five-Year Science and Technology Project (Grant No. 2011BAD16B14)
文摘In order to clarify the effects of aeration on root nitrogen metabolism in rice seedlings,rice cultivars Guodao 6 (indica) and Xiushui 09 (japonica) were investigated for root growth,the activities of glutamine synthetase (GS),glutamic acid-pyruvic acid transaminase (GPT) and glutamic acid oxaloacetate transaminase (GOT),the nitrate (NO 3-N) concertration,the contents of free amino acids and soluble sugar in root under hydroponics with continuous aeration treatment.The results showed that rice seedlings grown in oxygenation solutions had higher root dry matter,longer root length,stronger root activity and larger root absorption area compared with the control.In addition,the contents of soluble sugar,root vigor and the activities of GS,GOT and GPT in the aeration solutions were higher than those in the control.The results also indicated that the activities of enzymes involved in root nitrogen metabolism of Xiushui 09 were enhanced by aeration,however,there was no significant influence on root nitrogen metabolism of Guodao 6,which suggested that effect of oxygenation on rice root nitrogen metabolism might be genotype-specific.
基金the National Natural Science Foundation of China(No.51374035)the Foundation for the Author of National Excellent Doctoral Dissertation of PR China(No.201351)the Program for New Century Excellent Talents in University of China(No.NCET-13-0669).
文摘Despite lots of techniques in improving the heap leaching performance,many constraints on the industrial applications remain.We proposed a correspondingly effective and new idea of introducing forced aeration to improve the bad permeability and leaching effect of Yangla Copper Mine(YCM)during heap leaching.The dual-media theory was employed to study the impact mechanism of forced aeration on the variations of porous and fractured media during the column leaching experiments.An X-Ray Computed Tomography(CT)set was utilized to perform the pore imaging of the specimens and the fracture morphology of the particles within the columns was analyzed by Scanning Electron Microscope(SEM)as aeration rate(AR)changed.The results show that there exists copious fine particles within the heap of YCM,the particle size distribution of which is not reasonable.The forced aeration can not only promote the development of the porous and fractured structures but effectively break the blocked seepage paths.Then the leaching degree is improved and the seepage performance of the solute within the solution is enhanced.Therefore,the forced aeration is probable of making the leaching performance greatly improved.
基金This work was supported by National Science Foundation for Excellent Young Scholars,China(No.51722401)Key Project of National Natural Science Foundation,China(No.51734001)Fundamental Research Funds for the Central Universities(No.FRF-TP-18-003C1).
文摘Bacterial community dynamics and copper leaching with applied forced aeration were investigated during low-grade copper sulphide bioleaching to obtain better bioleaching efficiency.Results illustrated that appropriate aeration improved bacterial concentrations and leaching efficiencies.The highest bacterial concentration and Cu^(2+)concentration after 14-d leaching were 7.61×10^(7) cells·mL^(−1) and 704.9 mg·L^(−1),respectively,at aeration duration of 4 h·d^(−1).The attached bacteria played a significant role during bioleaching from 1 to 7 d.However,free bacteria dominated the bioleaching processes from 8 to 14 d.This phenomenon was mainly caused by the formation of passivation layer through Fe3+hydrolysis along with bioleaching,which inhibited the contact between the attached bacteria and ore.Meanwhile,16S rDNA analysis verified the effect of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans on the bioleaching process.The results demonstrate the importance of free and attached bacteria in bioleaching.
文摘In order to develop an effective MIBK removal method of H 2TaF 7 solution in tantalum extraction process, MIBK removal from aqueous solution by the aeration method was investigated by using an aeration column with the dimensions of 78 mm in inner diameter and 1 100 mm in length. The effects of aeration conditions on aerating efficiency were investigated in the ranges of temperature 303 333 K, airflow rate 50 300 L/h,volume of solution 1 600 3 200 mL. Aerating efficiency increases with the increase of temperature and airflow rate. MIBK in aqueous solution can be removed from 0.058 mol/L to 0.002 mol/L at 50 ℃,airflow rate 200 L/h, volume of solution 2 400 mL and aeration time 1h. The experimental results show that MIBK can be removed effectively from aqueous solution by the aeration method.
基金Supported by the Post-Doctoral Training Program from Research Affairs and Graduate School,Khon Kaen University(KKU).Thailand(Grant no.59153)
文摘To improve the efficiency of ethanol production in a batch fermentation from sweet sorghum juice under a very high gravity(VHG)condition(~290 g/L of total sugar)by Saccharomyces cerevisiae NP01,repeatedbatch fermentation under an aerated condition(2.5 vvm for the first 4 h during every cycle)was done in a5-L fermenter.The average ethanol concentration(P),productivity(Qp)and yield(Yp/s)for five successive cycles were 112.31 g/L,1.55 g/L·h^-1 and 0.44,respectively with 80.97%sugar consumption.To complete sugar consumption,the total sugar of the juice was reduced to a high gravity(HG)level(~240 g/L).The results showed that yeast extract was not necessary for ethanol production,and aeration during every other cycle i.e.,alternating cycles,was sufficient to promote both yeast growth and ethanol production.The average P,Qpand Yp/svalues for eight successive cycles with aeration during alternating cycles were97.58 g/L,1.98 g/Láh and 0.41,respectively with 91.21%sugar consumption.The total fatty acids in the yeast cells under the aerated condition were^50%higher than without aeration,irrespective the initial sugar concentration,whereas the ergosterol contents under aeration condition were^29%to 49%higher than those without aeration.
文摘The effects of soil aeration on physiological characters and root tuber yield of Ipomoea batatas (L.) Lam. CV Lushu7 and Xushu18 were studied. The results showed that soil aeration improvement could increase ATP content and ATPase activity in functional leaves and root tubers and ABA content in root tubers.It also accelerated the transportation of 14C-photosynthate from leaves to root tubers and enhanced dry matter distribution in root tubers and thus root tuber yield was significantly raised. The role of ATP, ATPase and ABA in accelerating the transportation of 14C-photosynthate was discussed based on the changes of soluble carbonhydrate content in sweet potato plant.
基金supported by the National Key Research and Development Plan of China(Grant No.2017YFD0801102)the Central Public-Interest Scientific Institution Basal Research Fund,China(Grant No.2017RG006-5)+1 种基金the National Science Foundation of China(Grant No.31701407)the Chinese Academy of Agricultural Sciences to the Scientific and Technical Innovation Team.
文摘Different cadmium(Cd)-accumulated rice genotypes(Erjiunan 1 and Fupin 36)were used to explore the effect of rice rhizosphere aeration on Cd uptake and accumulation.Aeration in the nutrient soluti on influe need the agronomic characteristics in duced by Cd-stress,such as the in creases of rice root length and root vigor,but the reductions of plant height and shoot dry weight.Aeration also alleviated the decreasing effects of Cd stress on antioxidant enzyme activities and soluble protein,malonaldehyde and nicotianamine contents in rice.Moreover,with aeration treatment,the accumulation and bioavailability of metal elements changed significantly,with a Cd increase and an Fe reduction in both rice genotypes.In addition,at the molecular level,aeration upregulated the expression of Fe-inducible genes(such as OsIRTI,OsNRAMPI,OsYSL15 and OsNAS3).Furthermore,as a Cd^(2+)/Fe^(2+) transporter,the high transcription level of OsNRAMPI can elevate the Cd uptake and translocation in rice due to the Fe reduction caused by aeration and Cd-exposure,which indicated that OsNRAMPI might play a crucial role in the effect of aeration on Cd uptake and accumulation.
基金Supported by the National Natural Science Foundation of China(No.51979236)the Sichuan Science and Technology Program(No.2019YFH0127)the Water Conservancy Science and Technology project of Shaanxi Province(No.2019slkj-1).Ming LI was funded as a Tang Scholar by the Cyrus Tang Foundation and Northwest A&F University。
文摘Aeration is an important measure to prevent cyanobacterial growth in eutrophic lakes and reservoirs.The purpose of this study is to clarify the infl uence of aeration induced turbulence on growth and competition of Microcystis and Scenedesmus in the presence of sediments with varying particle sizes.Microcystis aeruginosa and Scenedesmus obliquus were selected as the model organisms.Sediments with varying particle sizes were added into mono and mixed cultures of the organisms.In the absence of sediment,both low-and high-intensity aerations(the turbulent dissipation rates were 1.60×10^(-6)and 1.16×10^(-5)m^(2)/s^(3),respectively)promoted the growth of Scenedesmus,but the growth of Microcystis was inhibited particularly obvious under the high-intensity aeration conditions.In the presence of sediment,Scenedesmus was promoted under all aeration conditions,while Microcystis was inhibited.The inhibition rate of Microcystis decreased with the increase of sediment size when treated with low-intensity aeration in the nighttime.The highest inhibition rate of M.aeruginosa(89.2%)was identifi ed under the condition of low-intensity aeration in the nighttime with small sediment addition.Furthermore,our results indicated that the impacts of sediment-induced light intensity reduction on algal growth were insignifi cant.In the mixed culture,the growth of Microcystis was inhibited by Scenedesmus in all treatments with aeration.Our results provided a theoretical basis for the practice in controlling cyanobacteria by aeration.
文摘Recently a research team at Ohio University,USA,conducted a unique full-scale feld load test to simulate the aeration pipe installations at a copper extraction mine operated in Chile.The overliner material taken from the mine was used in recreating the in situ conditions.Electric heaters were utilized to raise the temperature inside each pipe to simulate the essential element of the copper extraction process.The maximum vertical deflection reached by the test pipes was close to 20%,when the simulated heap pile height was 80 m.The plastic pipes and the overliner material were also tested in the laboratory.Based on the results,the maximum heap pile fll depth was recommended for the aeration system.The results indicated that the vertical deflection was the primary performance index for the aeration pipes installed in heap piles at mines.Lastly,the pipe made of polypropylene resin was super.
基金Sponsored by the National Natural Science Foundation of China(Grant No.51109071)
文摘In order to accelerate the consolidation of the dredged sludge and look for an effective material for mud-water separation,the study on the comparison of geotextiles is carried on. It is based on the laboratory model test of aeration vacuum rapid mud- water separating( AVMWS) technique and evaluated by the cumulative weight of pumping water,the decrease of moisture content and the stable pumping speed. The results show that woven fabric is the best anti- clogging aeration vacuum material,followed by machine-woven fabric and non-woven fabric is the worst. The analysis has been proposed from two aspects of geotextile weaving technology and aeration vacuum condition.
文摘With autotrophic microalgae cultivation,?we can feed back the CO2?content of process streams and we can get lots of valuable organic compounds, among others biofuel components. For the production of energy source,we must reckon with the energy balance of the whole process. Densification and processing of microalgae can consume 50% - 70% of the energy that can be extracted from the cells,?therefore the cultivation should use such a little energy as it possible. In closed cultivation systems,?there are three main energy intensive steps: artificial illumination, dissolution of gas compounds and mixing. We have carried out our measurements in our lab-scale screening photobioreactor system for the investigation of the most energy effective program for aeration. We have found the aeration program considerable solution for lower energy consumption in?algae cultivation.
基金National Natural Science Foundation of China(No.21173026)Key Program of the Natural Science Foundation of Hubei Province(No.2013CFA107).
文摘A membrane bioreactor(MBR)with ordinary aeration(reactor R1)and a MBR with microporous aeration(reactor R2)are conducted in parallel to investigate the characteristics of oily sludge and its effect on membrane fouling.The results indicate that the order of membrane fouling rate from high to low is:reactor R1 dissolved oxygen(DO)(1 mg/L)>reactor R2 DO(1 mg/L)>reactor R1 DO(4 mg/L)>reactor R2 DO(4 mg/L).Membrane fouling rate is not related to oily sludge concentration but to oily sludge sedimentation performance and the small particle oily sludge is the key factor to affect the membrane fouling.The soluble microbial products(SMP)are examined by three-dimensional excitation-emission matrix(3DEEM)fluorescence spectra.3DEEM spectra demonstrate that the main organic substances of the SMP in two reactors are tyrosine aromatic protein,fulvic acid-like substances and soluble microbial products under DO are1 mg/L and 4 mg/L,respectively.The proportion sum of fulvic acid-like substances and soluble microbial products is the key factor affecting membrane fouling,and membrane fouling accelerates as the ratio increases.
基金the financial support from FAPESP(Fundacao de Amparo a Pesquisa do Estado de Sao Paulo—Process Number 2016/06683-0)the CNPq(Conselho Nacional de Desenvolvimento Cientifico e Tecnologico-Process Number 455260/2014-1)financed in part by the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior—Brasil(CAPES)—Finance Code 001.
文摘In the present study, the yeast Rhodotorula glutinis has been assessed with the aim of producing microbial lipids from glycerol under different aeration conditions. For such a purpose, experiments were carried out in shake flasks, under different conditions of agitation (150 to 250 rpm) and aeration (2.5 to 5.0 of flask volume-to-medium volume ratio). Furthermore, their influence on fermentative parameters (lipid and cell concentration, biomass yield;lipid yield;and lipid volumetric productivity) has been investigated using a 22 full factorial design. The statistical analysis has revealed a strong influence of both variables on substrate consumption, lipid accumulation, cell growth and lipid productivity. As a whole, results suggest that higher aeration levels provide greater cell and lipid concentrations, and lipid volumetric productivity. The best results (4.5 g/L of lipids and QP = 0.95 g/L⋅day) were achieved at the highest aeration (5.0 flask volume-to-medium volume ratio) and agitation (250 rpm) levels. Their fatty acid profile showed that oleic acid was produced in greater quantity (53.5%), followed by linoleic acid (18.7%), palmitic acid (6.8%) and stearic acid (9.9%). The microbial oil presented viscosity of 39.3 cP at 50°C and free fatty acid content of 1.93% ± 0.08%. These are significant results and contribute to establishing operational conditions that maximize single-cell oil production from glycerol by Rhodotorula glutinis, i.e. an alternative source as renewable raw material for lipid-based biorefineries.
文摘The aim of this work was the determination of the optimal aerations, and more specifically the corresponding optimal air velocities uopt, at which the largest COD removals were achieved in treatment of industrial wastewaters of various strength conducted in the inverse fluidized bed biofilm reactor. The largest COD removals were achieved at the following air velocities uopt and retention times ts, and (Vb/VR) = 0.55: i) for CODo = 72,780 mg/l at uopt = 0.052 m/s and ts = 80 h;ii) for CODo = 62,070 mg/l at uopt = 0.042 m/s and ts = 65 h;iii) for CODo = 49,130 mg/l at uopt = 0.033 m/s and ts= 55 h;iv) for CODo = 41,170 mg/l at uopt = 0.028 m/s and ts = 45 h;v) for CODo = 35,460 mg/l at uopt = 0.025 m/s and ts = 27.5 h;and vi) for CODo = 26,470 mg/l at uopt= 0.014 m/s and ts = 22.5 h. In the treatment operation conducted in a reactor optimally controlled at the above values of uopt, ts and (Vb/VR), the following decreases in COD were obtained: i) from 72,780 to 5410 mg/l;ii) from 62,070 to 3730 mg/l;iii) from 49,130 to 2820 mg/l;iv) from 41,170 to 1820 mg/l;v) from 35,460 to 1600 mg/l;and vi) from 26,470 to 1180 mg/l, that is, approximately a 93%, 94%, 95%, 96%, 95% and 96% COD reduction was attained, respectively.
基金Supported by Key Project of National Water Pollution Control and Treatment Science and Technology(2014ZX07211-001)Demonstration Study on Integration Model of Environmental Public Utilities in Industrial Parks of Key Watershed(2014ZX07211-001-04)
文摘In order to protect quality of Baiyangdian surface water and Gaoyang groundwater,the project is applied to process printing and dyeing wastewater that contains complicated compositions,high concentrations of organics and SS,and lots of pollutants difficult to degrade by microorganism. The process and operating parameters of project are optimized and debugged,and its economic and environmental benefits are analyzed.The results show that the process of coagulation sedimentation-hydrolytic acidification with aeration tank-biological aerated filter-active sand filter is applied in Gaoyang Sewage Treatment Plant. The design scale of sewage treatment plant is 120000 m^3/d. The influent is as following: COD is 669mg/L; SS is 424mg/L; NH_3-N is 8.83mg/L; TP is 6.03mg/L. After the process,the best removal rates of COD,SS,NH_3-N and TP are 93. 5%,98. 8%,97. 1% and 96. 2%,respectively. The various indexes of effluent water complied with standard A of the first order in Pollutants Emission Standard of Urban Wastewater Treatment Plant( GB 18918-2002). The processing cost is only 0. 807 yuan/m^3. As a result,the project construction and operation not only improve the environment,but also promote regional economic development. Process design and operating parameters provide an important reference value for the printing and dyeing wastewater treatment industry.
