This study advances the DRASTIC groundwater vulnerability assessment framework by integrating a multi-hazard groundwater index(MHGI)to account for the dynamic impacts of diverse anthropogenic activities and natural fa...This study advances the DRASTIC groundwater vulnerability assessment framework by integrating a multi-hazard groundwater index(MHGI)to account for the dynamic impacts of diverse anthropogenic activities and natural factors on both groundwater quality and quantity.Incorporating factors such as population growth,agricultural practices,and groundwater extraction enhances the framework’s ability to capture multi-dimensional,spatiotemporal changes in groundwater vulnerability.Additional improvements include refined weighting and rating scales for thematic layers based on available observational data,and the inclusion of distributed recharge.We demonstrate the practical utility of this dynamic DRASTIC-based framework through its application to the agro-urban regions of the Irrigated Indus Basin,a major groundwater-dependent agricultural area in South Asia.Results indicate that between 2005 and 2020,54%of the study area became highly vulnerable to pollution.The MHGI revealed a 13%decline in potential groundwater storage and a 25%increase in groundwater-stressed zones,driven primarily by population growth and intensive agriculture.Groundwater vulnerability based on both groundwater quality and quantity dimensions showed a 19%decline in areas of low to very low vulnerability and a 6%reduction in medium vulnerability zones by 2020.Sensitivity analyses indicated that groundwater vulnerability in the region is most influenced by groundwater recharge(42%)and renewable groundwater stress(38%).Validation with in-situ data yielded area under the curve values of 0.71 for groundwater quality vulnerability and 0.63 for MHGI.The framework provides valuable insights to guide sustainable groundwater management,safeguarding both environmental integrity and human well-being.展开更多
The mechanical, physical and thermal characterization of a composite made from woven raffia fiber vinifiera molded in epoxy resin intended for shipbuilding shows that the density (0.5 g/cm3 with a relative error of 0....The mechanical, physical and thermal characterization of a composite made from woven raffia fiber vinifiera molded in epoxy resin intended for shipbuilding shows that the density (0.5 g/cm3 with a relative error of 0.05 g/cm3) of the composite produced is lower than that of wood used in this field. The material has low porosity (9.8%) and is less absorbent (12.61%) than wood. The result of the thermal conductivity test by the hot plane method shows that this composite can contribute to the internal thermal insulation (an example of thermal conductivity is 0.32W/m.K) of floating boats. The mechanical tests of compression (young modulus is 22.86 GPa), resilience (1.238 J/Cm2) and hardness (233.04 BH30-2.5/187.5-15s) show that this composite is much harder and more absorbent than many wood and bio-composite materials used in the construction of pleasure boats. The abrasion test (0.005349) shows that this composite could well resist friction with the beach.展开更多
To understand the long-term performance of bioretention systems under sulfamethoxazole (SMX) stress, an unplanted bioretention system (BRS) and two modified BRSs with coconut-shell activated carbon (CAC) and CAC/zero-...To understand the long-term performance of bioretention systems under sulfamethoxazole (SMX) stress, an unplanted bioretention system (BRS) and two modified BRSs with coconut-shell activated carbon (CAC) and CAC/zero-valent-iron (Fe^(0)) granules (CAC-BRS and Fe/CAC-BRS) were established. Both CAC-BRS and Fe/CAC-BRS significantly outperformed BRS in removing total nitrogen (TN)(CAC-BRS:82.48%;Fe/CAC-BRS:78.08%;BRS:47.51%), total phosphorous (TP)(CAC-BRS:79.36%;Fe/CAC-BRS:98.26%;BRS:41.99%),and SMX (CAC-BRS:99.74%, Fe/CAC-BRS:99.80%;BRS:23.05%) under the long-term SMX exposure (0.8 mg/L, 205 days). High-throughput sequencing revealed that the microbial community structures of the three BRSs shifted greatly in upper zones after SMX exposure.Key functional genera, dominantly Nitrospira, Rhodoplanes, Desulfomicrobium, Geobacter,were identified by combining the functional prediction by the FAPROTAX database with the dominant genera. The higher abundance of nitrogen functional genes (nirK, nirS and nos Z) in CAC-BRS and Fe/CAC-BRS might explain the more efficient TN removal in these two systems. Furthermore, the relative abundance of antibiotic-resistant genes (ARGs)sul I and sulII increased in all BRSs along with SMX exposure, suggesting the selection of bacteria containing sul genes. Substrates tended to become reservoirs of sul genes. Also,co-occurrence network analysis revealed distinct potential host genera of ARGs between upper and lower zones. Notably, Fe/CAC-BRS succeeded to reduce the effluent sul genes by1-2 orders of magnitude, followed by CAC-BRS after 205-day exposure. This study demon-strated that substrate modification was crucial to maintain highly efficient nutrients and SMX removals, and ultimately extend the service life of BRSs in treating SMX wastewater.展开更多
The dynamics of Cd scavenging from solutions by Fe/Mn oxides in natural surface coatings （NSCs） was investigated under laboratory conditions. Selective extraction methods were employed to estimate the contributions ...The dynamics of Cd scavenging from solutions by Fe/Mn oxides in natural surface coatings （NSCs） was investigated under laboratory conditions. Selective extraction methods were employed to estimate the contributions of Fe/Mn oxides, where hydroxylamine hydrochloride （0.01 mol/L NH2OH-HCl ＋ 0.01 mol/L HNO3）, sodium dithionite （0.4 mol/L Na2S2O4） and nitric acid （10% HNO3） were used as extraction reagents. The Cd scavenging was accomplished with developing periods of the NSCs （totally 21 data sets）. The resulting process dynamics fitted well to the Elovich equation, demonstrating that the amount of Cd scavenged was proportional to the increments of Fe/Mn oxides that were accumulated in the NSCs. The amount of Cd bound to Fe oxides （MCdFe） and Mn oxides （MCdMn） could be quantified by solving two equations based on the properties of two extraction reagents. The amount of Cd scavenged by Fe/Mn oxides could also be estimated using MCdFe and MCdMn divided by the total amounts of Fe and Mn oxides in the NSCs, respectively. The results indicated that the Cd scavenging by Fe/Mn oxides was dominated by Fe oxides, with less roles attributed to Mn oxides. The estimated levels of Cd scavenging through Fe and Mn oxides agreed well with those predicted through additive-adsorption and linear-regression models.展开更多
The main objective of this study was to determine the desiccation behavior of clay slurries. A clay slurry with high water adsorption capacity(W_L = 180%,W_P 60%,W_s = 20) was used to determine the soil water characte...The main objective of this study was to determine the desiccation behavior of clay slurries. A clay slurry with high water adsorption capacity(W_L = 180%,W_P 60%,W_s = 20) was used to determine the soil water characteristic curve(SWCC), shrinkage curve, and hydraulic conductivity. The last parameter was determined similar to the Instantaneous Profile Method using evaporation tests. Results indicated that the clay slurry had an air entry value(AEV) of 1000 kPa and a residual suction of 5000 kPa that occurred at the plastic limit and the shrinkage limit, respectively. The discrepancy between theoretical and measured shrinkage limit was due to the gradual increase in clay particle contact. Unlike soils, the saturated hydraulic conductivity varied by two orders of magnitude(4×10 ~10 m/s at 20 kPa to 3 x 10 ~12 m/s at AEV). The unsaturated k further decreased to 10 ~14 m/s at 6 x 10~4 kPa beyond which vapor flow took place.展开更多
This paper investigates the geotechnical behavior of uranium mill tailings from Saskatchewan,Canada.The 4%tailings were well-graded with 29%fines whereas the 5%and 6%tailings were gap-graded with 49%fines.All samples ...This paper investigates the geotechnical behavior of uranium mill tailings from Saskatchewan,Canada.The 4%tailings were well-graded with 29%fines whereas the 5%and 6%tailings were gap-graded with 49%fines.All samples exhibited a negligible strength(0.4 k Pa)up to 60%solids,followed by a rapid increase.The 4%tailings exhibited a lower rate and amount of settlement than 5%and 6%tailings.The kidecreased from 10^(-2)to 10^(-4)m/s with a decrease in eifrom 16 to 4 and a decrease in ef from 8 to 4 such that 4%tailings showed one order of magnitude lower values than the 5%and 6%tailings.The settling potential decreased ten times(50%-5%)for 4%tailings and four times(60%-15%)for 5%and 6%tailings.The effective stress increased from 80 to 260 Pa in the settling tests.The 4%tailings were less prone to segregation when compared with 5%and 6%tailings.The average solids content after settling was 35%for 4%tailings,40%for 5%tailings and 39%for 6%tailings with a solids content deviation of±3%,±8%,±6%,respectively.All materials were essentially non-segregating at 40%initial solids.展开更多
The new turning method was proposed and verified its effectiveness to pathogens by laboratory scale experiments.Considering the results obtained from the previous studies,it could be said that turning of a composting ...The new turning method was proposed and verified its effectiveness to pathogens by laboratory scale experiments.Considering the results obtained from the previous studies,it could be said that turning of a composting pile was essential in terms of hygienic aspects but the number of turning should be minimized.Effectiveness of inactivation was estimated for each composting run.From this estimation,turning by layers,which is different from conventional turning that mixes compost pile entirely,was proposed and investigated its performance by experiments.Composting operations with static pile method,complete mix(conventional)turning method,and proposed turning(layer turning)method were done and their effectiveness on inactivation of indicator microorganism was evaluated and compared.As results,the conventional turning method was not a proper method in terms of pathogen inactivation,whereas,the proposed turning method showed an excellent performance and should be employed in a composting operation.展开更多
The main objective of this study was to determine the consolidation behaviour of clay slurries.A finegrained clay with high consistency limits(W_L = 180%,w_P= 120%) was investigated using conventional oedometer and be...The main objective of this study was to determine the consolidation behaviour of clay slurries.A finegrained clay with high consistency limits(W_L = 180%,w_P= 120%) was investigated using conventional oedometer and bench-top centrifuge tests.Results indicated that the slurry had an apparent preconsolidation(due to initial conditions,electrochemical interactions,tortuous drainage,and thixotropic strength) from e = 5.7 to e = 5.5 followed by virgin compression.Likewise,the low hydraulic conductivity(10^(-10)-10^(-12) m/s) was due to low porosity(small pore throats) and high tortuosity(long flow paths).Unlike consolidation of soils,the c_v and m_v decreased with increasing σ' but increased with increasing e and k.The data from the two tests correlated well in the range of σ' = 10-65 kPa,e = 5.5-3.86,k= 1.7 × 10^(-10)-5×10^(-11) m/s,F_c = 1-40 MN.New equations were developed to correlate the consolidation parameters(e,σ',k) with F_c.The deviation of k beyond 40 MN(e = 4.65) was due to deviation from the initial straight line portion of the settlement curve in the centrifuge test.展开更多
Bench-scale treatments with three mixtures of Mg and P salts, including K3PO4＋MgSO4, K2HPO4＋MgSO4, and KH2PO4＋MgSO4 as additives in a simulated food waste aerobic composting process, were conducted to test the magn...Bench-scale treatments with three mixtures of Mg and P salts, including K3PO4＋MgSO4, K2HPO4＋MgSO4, and KH2PO4＋MgSO4 as additives in a simulated food waste aerobic composting process, were conducted to test the magnesium ammonium phosphate（MAP） formation, and the compost products were analyzed by X-ray diffraction（XRD）, Scanning electron microscopy（SEM）, and Energy dispersive X-ray spectroscopy（EDS） analyses. The comparison results between XRD, SEM, and EDS analyses of MAPs in the dried compost and synthesized MAPs confirm the formation of MAP crystals in the simulated food waste aerobic composting process. The analysis of the compost also indicates that the addition of all the three mixtures of Mg and P salts in the aerobic composting process can increase nitrogen conservation and decrease nitrogen loss because of the formation of MAPs. The mechanism of MAP formation was verified as the reaction of ammonium（NH4＋） with magnesium（Mg^2＋） and phosphate[HnPO4^（3-n） , n=0, 1, and 2）.展开更多
In the mid-eastern China,there are few or no lakes which are in the absence of anthropogenic disturbances,or their sediments remain undisturbed.As a result,the reference lakes distribution and paleolimnological recons...In the mid-eastern China,there are few or no lakes which are in the absence of anthropogenic disturbances,or their sediments remain undisturbed.As a result,the reference lakes distribution and paleolimnological reconstruction approaches usually are inappropriate to estimate lake reference conditions for nutrients.This yields the necessity of using the extrapolation methods to estimate the lake reference conditions for nutrients within those regions.The lake reference conditions for nutrients could be inferred inversely from the law of mass conservation,current lake nutrient concentration,and the loadings from watershed.Considering the scarcity of hydrological and water quality data associated with lakes and watersheds in China,as well as the low requirement of the watershed nutrient loadings models for these data,the soil conservation service(SCS) distributed hydrological model and the universal soil loss equation(USLE) were applied.The SCS model simulates the runoff process of the watershed,thereby calculating dissolved nutrients annually.The USLE estimates the soil erosion and particulate nutrients annually in a watershed.Then,with the loadings from atmospheric deposition and point source,the previous annual average nutrient concentrations could be acquired given the current nutrient concentrations in a lake.Therefore,the nutrient reference conditions minimally impacted by human activities could be estimated.Based on the proposed model,the reference conditions for total nitrogen and total phosphorus of Chaohu Lake,Anhui Province,China are 0.031 mg/L and 0.640 mg/L,respectively.The proposed reference conditions estimation model is of clear physical concept,and less data required.Thus,the proposed approach can be used in other lakes with similar circumstances.展开更多
A mathematical model for the catalytic autothermal reforming(ATR)reaction of synthetic crude glycerol to hydrogen in a fixed bed tubular reactor(FBTR)and over an in-house developed metal oxide catalyst is presented in...A mathematical model for the catalytic autothermal reforming(ATR)reaction of synthetic crude glycerol to hydrogen in a fixed bed tubular reactor(FBTR)and over an in-house developed metal oxide catalyst is presented in this work.The heterogeneous model equations account for a two-phase system of solid catalyst and bulk feed gas.Also,the ATR of crude glycerol reaction scheme and intrinsic kinetic rate model over an active,selective,and stable nickel-based catalyst were integrated in the developed model.Also,the model was validated using experimental data generated in our labs for the ATR of synthetic crude glycerol.The modelling results adequately described the detailed gas product composition and distribution,temperature profiles,and conversion propagation in the axial direction of the fixed bed reactor over a wide range of reaction temperature(773–923 K)and mass-time(12.71–158.23 g cat·min·(mol C)^(-1)).The crude glycerol conversion predicted with the model showing a close resemblance to those obtained experimentally with an average absolute deviation(AAD)of less than 8%.The maximum crude glycerol conversion and hydrogen yield were found to be 92%and 3 mol hydrogen/mol crude glycerol,respectively.Also,the gas product concentration profile in the reactor was adequately described(90%)accuracy with a hydrogen concentration of 39%(volume).展开更多
Planning for water quality management is important for facilitating sustainable socio-economic development;however, the planning is also complicated by a variety of uncertainties and nonlinearities. In this study, an ...Planning for water quality management is important for facilitating sustainable socio-economic development;however, the planning is also complicated by a variety of uncertainties and nonlinearities. In this study, an interval-parameter fuzzy robust nonlinear programming (IFRNP) model was developed for water quality management to deal with such difficulties. The developed model incorporated interval nonlinear programming (INP) and fuzzy robust programming (FRP) methods within a general optimization framework. The developed IFRNP model not only could explicitly deal with uncertainties represented as discrete interval numbers and fuzzy membership functions, but also was able to deal with nonlinearities in the objective function.展开更多
Polycyclic aromatic hydrocarbons(PAHs)are persistent and widespread in the aquatic environment,causing potential hazards for human health.In this study,a superwetting and robust PES-PAA-ZrO_(2)nanofiltration membrane ...Polycyclic aromatic hydrocarbons(PAHs)are persistent and widespread in the aquatic environment,causing potential hazards for human health.In this study,a superwetting and robust PES-PAA-ZrO_(2)nanofiltration membrane was proposed through surface modification for PAH removal with high efficiency.A ZrO_(2)coating was formed on polyethersulfone(PES)membrane surface through chemical bonding,thus the PES-PAA-ZrO_(2)membrane exhibited super-hydrophilicity,under-water oleophobicity,and excellent stability.In comparison with the original PES membrane,the water contact angle of the modified membrane was significantly decreased from about 50°to less than 10°,and quickly dropped to 0°within 1s.This provided a much lower energy barrier for water permeation due to its super-high water affinity.The wastewater treatment efficiency was increased by about 4 times after modification with more than 90%of PAH rejection rate.The excellent robustness of PES-PAA-ZrO_(2)membrane was verified under various conditions,which gave the membrane practical potential for long-term operation.展开更多
In the field of organic syntheses, the development of environmentally friendly methods based on the concept of green chemistry has been always required. In response to this requirement, we reported solvent- and cataly...In the field of organic syntheses, the development of environmentally friendly methods based on the concept of green chemistry has been always required. In response to this requirement, we reported solvent- and catalyst-free syntheses of imines using the pressure reduction technique as a key technology. We found that this reaction proceeded very rapidly in the initial stage, but its rate decreased with the passage of time. It was also found that the reaction of benzaldehyde with aniline had a specificity that the phase transition occurred. In this method, the desired imines could be obtained in good to excellent yields, but target compounds had to be given by purifications using organic solvents. Therefore, we tried to develop the perfect synthetic method of imine derivatives without organic or inorganic solvents. We selected two methods and took them into this investigation. One was exactly mixing (1:1, substance ratio) aldehydes and amines and the other was employing lower pressure (>0.1 mmHg, previous method: 1.0 mmHg) at the pressure reducing technique. When this improved synthetic method was performed, it was revealed that pure target imines were obtained in excellent yields without any purification.展开更多
Because imines could be used as convenient starting materials in various fields, the development of an easy synthetic method of imine was strongly desired. In response to this demand, we thought that it would be an ef...Because imines could be used as convenient starting materials in various fields, the development of an easy synthetic method of imine was strongly desired. In response to this demand, we thought that it would be an effective synthesis method if an aldehyde and an amine could be reacted to give an imine in good yield under solvent- and catalyst-free conditions. In fact, we tried the reaction of benzaldehyde with various amines under solvent- and catalyst-free conditions followed by removal of water that was produced in the reaction system by a vacuum pump, and desired imines could be obtained in good yields. Observation of this reaction using a nuclear magnetic resonance spectrometer revealed that the reaction rate was extremely fast at the initial stage but slowed over time. However, the reaction of benzaldehyde with aniline differed greatly, and the reaction rate dramatically improved in 47 - 48 minutes after the start of the reaction. At this time, we found that the reaction system underwent a phase transition from the liquid phase to the solid phase.展开更多
Alginate is a widely used polymer matrix in food industry since it allows formation of spherical, soft, and strong membranes adequate for encapsulation of a large amount of products, including food. The flow rate of a...Alginate is a widely used polymer matrix in food industry since it allows formation of spherical, soft, and strong membranes adequate for encapsulation of a large amount of products, including food. The flow rate of alginate solutions and the permeability of the capsules were evaluated within an acidic-low acidic pH range and different alginate concentrations. In solutions adjusted at different pH （3.0 to 7.0） with concentrations of alginate of 0.8, 1.0, and 1.2% w/v, flow rates at 20 ℃ were 6.95 to 10.00, 4.54-5.35, and 2.60-2.80 mL sl, respectively. Permeability of the capsules was evaluated in terms of the diffusion of H＋ions （expressed as pH） and soluble solids （~Brix）. Meanwhile both diffusions were minor at 4.0 〈 pH 〈 7.0 and were significantly superior at more acidic pH （P 〈 0.05）, alginate concentration did not present significant effect. Yellow, purple, and red juices from Stenocereus spp. fruits （pitayas） were encapsulated using 1.0% of alginate and stored with isotonic solution （3 mL g^-1） at 4 ℃ in the dark. The capsules were spherical with diameter between 4.59 and 470 mm, weight from 82.60 to 97.50 rag, and volume of 0.075-0.098 mL. Pigment （total betalains content） diffusion reached equilibrium at 24 h of storage, at which point retentions of total betalains in the yellow, purple, and red capsules were 87.79, 96.13, and 85.13%, respectively. Also, changes in the color of the capsules were observed during storage.展开更多
基金funding from the National Science Foundation(NSF Award 2114701)of the United States.
文摘This study advances the DRASTIC groundwater vulnerability assessment framework by integrating a multi-hazard groundwater index(MHGI)to account for the dynamic impacts of diverse anthropogenic activities and natural factors on both groundwater quality and quantity.Incorporating factors such as population growth,agricultural practices,and groundwater extraction enhances the framework’s ability to capture multi-dimensional,spatiotemporal changes in groundwater vulnerability.Additional improvements include refined weighting and rating scales for thematic layers based on available observational data,and the inclusion of distributed recharge.We demonstrate the practical utility of this dynamic DRASTIC-based framework through its application to the agro-urban regions of the Irrigated Indus Basin,a major groundwater-dependent agricultural area in South Asia.Results indicate that between 2005 and 2020,54%of the study area became highly vulnerable to pollution.The MHGI revealed a 13%decline in potential groundwater storage and a 25%increase in groundwater-stressed zones,driven primarily by population growth and intensive agriculture.Groundwater vulnerability based on both groundwater quality and quantity dimensions showed a 19%decline in areas of low to very low vulnerability and a 6%reduction in medium vulnerability zones by 2020.Sensitivity analyses indicated that groundwater vulnerability in the region is most influenced by groundwater recharge(42%)and renewable groundwater stress(38%).Validation with in-situ data yielded area under the curve values of 0.71 for groundwater quality vulnerability and 0.63 for MHGI.The framework provides valuable insights to guide sustainable groundwater management,safeguarding both environmental integrity and human well-being.
文摘The mechanical, physical and thermal characterization of a composite made from woven raffia fiber vinifiera molded in epoxy resin intended for shipbuilding shows that the density (0.5 g/cm3 with a relative error of 0.05 g/cm3) of the composite produced is lower than that of wood used in this field. The material has low porosity (9.8%) and is less absorbent (12.61%) than wood. The result of the thermal conductivity test by the hot plane method shows that this composite can contribute to the internal thermal insulation (an example of thermal conductivity is 0.32W/m.K) of floating boats. The mechanical tests of compression (young modulus is 22.86 GPa), resilience (1.238 J/Cm2) and hardness (233.04 BH30-2.5/187.5-15s) show that this composite is much harder and more absorbent than many wood and bio-composite materials used in the construction of pleasure boats. The abrasion test (0.005349) shows that this composite could well resist friction with the beach.
基金supported by the National Natural Science Foundation of China (Nos. 41671468, 41967043)the Qing Lan Project of Jiangsu Province, Science and Technology Service Network Initiative (No. KFJ-STS-QYZX-051)+1 种基金the Educational and Teaching Reforms Project of Ministry of Education (No. GPSJZW2020-31)the Fundamental Research Funds for the Central Universities。
文摘To understand the long-term performance of bioretention systems under sulfamethoxazole (SMX) stress, an unplanted bioretention system (BRS) and two modified BRSs with coconut-shell activated carbon (CAC) and CAC/zero-valent-iron (Fe^(0)) granules (CAC-BRS and Fe/CAC-BRS) were established. Both CAC-BRS and Fe/CAC-BRS significantly outperformed BRS in removing total nitrogen (TN)(CAC-BRS:82.48%;Fe/CAC-BRS:78.08%;BRS:47.51%), total phosphorous (TP)(CAC-BRS:79.36%;Fe/CAC-BRS:98.26%;BRS:41.99%),and SMX (CAC-BRS:99.74%, Fe/CAC-BRS:99.80%;BRS:23.05%) under the long-term SMX exposure (0.8 mg/L, 205 days). High-throughput sequencing revealed that the microbial community structures of the three BRSs shifted greatly in upper zones after SMX exposure.Key functional genera, dominantly Nitrospira, Rhodoplanes, Desulfomicrobium, Geobacter,were identified by combining the functional prediction by the FAPROTAX database with the dominant genera. The higher abundance of nitrogen functional genes (nirK, nirS and nos Z) in CAC-BRS and Fe/CAC-BRS might explain the more efficient TN removal in these two systems. Furthermore, the relative abundance of antibiotic-resistant genes (ARGs)sul I and sulII increased in all BRSs along with SMX exposure, suggesting the selection of bacteria containing sul genes. Substrates tended to become reservoirs of sul genes. Also,co-occurrence network analysis revealed distinct potential host genera of ARGs between upper and lower zones. Notably, Fe/CAC-BRS succeeded to reduce the effluent sul genes by1-2 orders of magnitude, followed by CAC-BRS after 205-day exposure. This study demon-strated that substrate modification was crucial to maintain highly efficient nutrients and SMX removals, and ultimately extend the service life of BRSs in treating SMX wastewater.
基金The National Basic Research Program (973) of China (No. 2004CB3418501)
文摘The dynamics of Cd scavenging from solutions by Fe/Mn oxides in natural surface coatings （NSCs） was investigated under laboratory conditions. Selective extraction methods were employed to estimate the contributions of Fe/Mn oxides, where hydroxylamine hydrochloride （0.01 mol/L NH2OH-HCl ＋ 0.01 mol/L HNO3）, sodium dithionite （0.4 mol/L Na2S2O4） and nitric acid （10% HNO3） were used as extraction reagents. The Cd scavenging was accomplished with developing periods of the NSCs （totally 21 data sets）. The resulting process dynamics fitted well to the Elovich equation, demonstrating that the amount of Cd scavenged was proportional to the increments of Fe/Mn oxides that were accumulated in the NSCs. The amount of Cd bound to Fe oxides （MCdFe） and Mn oxides （MCdMn） could be quantified by solving two equations based on the properties of two extraction reagents. The amount of Cd scavenged by Fe/Mn oxides could also be estimated using MCdFe and MCdMn divided by the total amounts of Fe and Mn oxides in the NSCs, respectively. The results indicated that the Cd scavenging by Fe/Mn oxides was dominated by Fe oxides, with less roles attributed to Mn oxides. The estimated levels of Cd scavenging through Fe and Mn oxides agreed well with those predicted through additive-adsorption and linear-regression models.
基金the Natural Sciences and Engineering Research Council of Canada for providing financial assistance
文摘The main objective of this study was to determine the desiccation behavior of clay slurries. A clay slurry with high water adsorption capacity(W_L = 180%,W_P 60%,W_s = 20) was used to determine the soil water characteristic curve(SWCC), shrinkage curve, and hydraulic conductivity. The last parameter was determined similar to the Instantaneous Profile Method using evaporation tests. Results indicated that the clay slurry had an air entry value(AEV) of 1000 kPa and a residual suction of 5000 kPa that occurred at the plastic limit and the shrinkage limit, respectively. The discrepancy between theoretical and measured shrinkage limit was due to the gradual increase in clay particle contact. Unlike soils, the saturated hydraulic conductivity varied by two orders of magnitude(4×10 ~10 m/s at 20 kPa to 3 x 10 ~12 m/s at AEV). The unsaturated k further decreased to 10 ~14 m/s at 6 x 10~4 kPa beyond which vapor flow took place.
基金the University of Regina for providing laboratory space and computing facilitiesCameco Corporation for material and financial support
文摘This paper investigates the geotechnical behavior of uranium mill tailings from Saskatchewan,Canada.The 4%tailings were well-graded with 29%fines whereas the 5%and 6%tailings were gap-graded with 49%fines.All samples exhibited a negligible strength(0.4 k Pa)up to 60%solids,followed by a rapid increase.The 4%tailings exhibited a lower rate and amount of settlement than 5%and 6%tailings.The kidecreased from 10^(-2)to 10^(-4)m/s with a decrease in eifrom 16 to 4 and a decrease in ef from 8 to 4 such that 4%tailings showed one order of magnitude lower values than the 5%and 6%tailings.The settling potential decreased ten times(50%-5%)for 4%tailings and four times(60%-15%)for 5%and 6%tailings.The effective stress increased from 80 to 260 Pa in the settling tests.The 4%tailings were less prone to segregation when compared with 5%and 6%tailings.The average solids content after settling was 35%for 4%tailings,40%for 5%tailings and 39%for 6%tailings with a solids content deviation of±3%,±8%,±6%,respectively.All materials were essentially non-segregating at 40%initial solids.
文摘The new turning method was proposed and verified its effectiveness to pathogens by laboratory scale experiments.Considering the results obtained from the previous studies,it could be said that turning of a composting pile was essential in terms of hygienic aspects but the number of turning should be minimized.Effectiveness of inactivation was estimated for each composting run.From this estimation,turning by layers,which is different from conventional turning that mixes compost pile entirely,was proposed and investigated its performance by experiments.Composting operations with static pile method,complete mix(conventional)turning method,and proposed turning(layer turning)method were done and their effectiveness on inactivation of indicator microorganism was evaluated and compared.As results,the conventional turning method was not a proper method in terms of pathogen inactivation,whereas,the proposed turning method showed an excellent performance and should be employed in a composting operation.
基金the University of Regina for providing laboratory space and the Natural Science and Engineering Research Council of Canada for financial assistance
文摘The main objective of this study was to determine the consolidation behaviour of clay slurries.A finegrained clay with high consistency limits(W_L = 180%,w_P= 120%) was investigated using conventional oedometer and bench-top centrifuge tests.Results indicated that the slurry had an apparent preconsolidation(due to initial conditions,electrochemical interactions,tortuous drainage,and thixotropic strength) from e = 5.7 to e = 5.5 followed by virgin compression.Likewise,the low hydraulic conductivity(10^(-10)-10^(-12) m/s) was due to low porosity(small pore throats) and high tortuosity(long flow paths).Unlike consolidation of soils,the c_v and m_v decreased with increasing σ' but increased with increasing e and k.The data from the two tests correlated well in the range of σ' = 10-65 kPa,e = 5.5-3.86,k= 1.7 × 10^(-10)-5×10^(-11) m/s,F_c = 1-40 MN.New equations were developed to correlate the consolidation parameters(e,σ',k) with F_c.The deviation of k beyond 40 MN(e = 4.65) was due to deviation from the initial straight line portion of the settlement curve in the centrifuge test.
基金Supported by the Scholarship from China Scholarship Council(No.22822053)
文摘Bench-scale treatments with three mixtures of Mg and P salts, including K3PO4＋MgSO4, K2HPO4＋MgSO4, and KH2PO4＋MgSO4 as additives in a simulated food waste aerobic composting process, were conducted to test the magnesium ammonium phosphate（MAP） formation, and the compost products were analyzed by X-ray diffraction（XRD）, Scanning electron microscopy（SEM）, and Energy dispersive X-ray spectroscopy（EDS） analyses. The comparison results between XRD, SEM, and EDS analyses of MAPs in the dried compost and synthesized MAPs confirm the formation of MAP crystals in the simulated food waste aerobic composting process. The analysis of the compost also indicates that the addition of all the three mixtures of Mg and P salts in the aerobic composting process can increase nitrogen conservation and decrease nitrogen loss because of the formation of MAPs. The mechanism of MAP formation was verified as the reaction of ammonium（NH4＋） with magnesium（Mg^2＋） and phosphate[HnPO4^（3-n） , n=0, 1, and 2）.
基金Under the auspices of the Major Special Technological Program of Water Pollution Control and Management (No. 2009ZX07106-001)National Natural Science Foundation of China (No. 51079037,51109052)
文摘In the mid-eastern China,there are few or no lakes which are in the absence of anthropogenic disturbances,or their sediments remain undisturbed.As a result,the reference lakes distribution and paleolimnological reconstruction approaches usually are inappropriate to estimate lake reference conditions for nutrients.This yields the necessity of using the extrapolation methods to estimate the lake reference conditions for nutrients within those regions.The lake reference conditions for nutrients could be inferred inversely from the law of mass conservation,current lake nutrient concentration,and the loadings from watershed.Considering the scarcity of hydrological and water quality data associated with lakes and watersheds in China,as well as the low requirement of the watershed nutrient loadings models for these data,the soil conservation service(SCS) distributed hydrological model and the universal soil loss equation(USLE) were applied.The SCS model simulates the runoff process of the watershed,thereby calculating dissolved nutrients annually.The USLE estimates the soil erosion and particulate nutrients annually in a watershed.Then,with the loadings from atmospheric deposition and point source,the previous annual average nutrient concentrations could be acquired given the current nutrient concentrations in a lake.Therefore,the nutrient reference conditions minimally impacted by human activities could be estimated.Based on the proposed model,the reference conditions for total nitrogen and total phosphorus of Chaohu Lake,Anhui Province,China are 0.031 mg/L and 0.640 mg/L,respectively.The proposed reference conditions estimation model is of clear physical concept,and less data required.Thus,the proposed approach can be used in other lakes with similar circumstances.
基金the financial support provided by the Natural Science and Engineering Research Council of Canada (NSERC)the Canada Foundation for Innovation (CFI)
文摘A mathematical model for the catalytic autothermal reforming(ATR)reaction of synthetic crude glycerol to hydrogen in a fixed bed tubular reactor(FBTR)and over an in-house developed metal oxide catalyst is presented in this work.The heterogeneous model equations account for a two-phase system of solid catalyst and bulk feed gas.Also,the ATR of crude glycerol reaction scheme and intrinsic kinetic rate model over an active,selective,and stable nickel-based catalyst were integrated in the developed model.Also,the model was validated using experimental data generated in our labs for the ATR of synthetic crude glycerol.The modelling results adequately described the detailed gas product composition and distribution,temperature profiles,and conversion propagation in the axial direction of the fixed bed reactor over a wide range of reaction temperature(773–923 K)and mass-time(12.71–158.23 g cat·min·(mol C)^(-1)).The crude glycerol conversion predicted with the model showing a close resemblance to those obtained experimentally with an average absolute deviation(AAD)of less than 8%.The maximum crude glycerol conversion and hydrogen yield were found to be 92%and 3 mol hydrogen/mol crude glycerol,respectively.Also,the gas product concentration profile in the reactor was adequately described(90%)accuracy with a hydrogen concentration of 39%(volume).
文摘Planning for water quality management is important for facilitating sustainable socio-economic development;however, the planning is also complicated by a variety of uncertainties and nonlinearities. In this study, an interval-parameter fuzzy robust nonlinear programming (IFRNP) model was developed for water quality management to deal with such difficulties. The developed model incorporated interval nonlinear programming (INP) and fuzzy robust programming (FRP) methods within a general optimization framework. The developed IFRNP model not only could explicitly deal with uncertainties represented as discrete interval numbers and fuzzy membership functions, but also was able to deal with nonlinearities in the objective function.
基金supported by the National Key Research and Development Plan(2016YFA0601502)the Canada Research Chairs(CRC)Program+3 种基金the Canada Foundation for Innovation(CFI)the Natural Science and Engineering Research Council(NSERC)of CanadaWestern Canada Clean Energy Initiative(No.000015269)Petroleum Technology Research Centre
文摘Polycyclic aromatic hydrocarbons(PAHs)are persistent and widespread in the aquatic environment,causing potential hazards for human health.In this study,a superwetting and robust PES-PAA-ZrO_(2)nanofiltration membrane was proposed through surface modification for PAH removal with high efficiency.A ZrO_(2)coating was formed on polyethersulfone(PES)membrane surface through chemical bonding,thus the PES-PAA-ZrO_(2)membrane exhibited super-hydrophilicity,under-water oleophobicity,and excellent stability.In comparison with the original PES membrane,the water contact angle of the modified membrane was significantly decreased from about 50°to less than 10°,and quickly dropped to 0°within 1s.This provided a much lower energy barrier for water permeation due to its super-high water affinity.The wastewater treatment efficiency was increased by about 4 times after modification with more than 90%of PAH rejection rate.The excellent robustness of PES-PAA-ZrO_(2)membrane was verified under various conditions,which gave the membrane practical potential for long-term operation.
文摘In the field of organic syntheses, the development of environmentally friendly methods based on the concept of green chemistry has been always required. In response to this requirement, we reported solvent- and catalyst-free syntheses of imines using the pressure reduction technique as a key technology. We found that this reaction proceeded very rapidly in the initial stage, but its rate decreased with the passage of time. It was also found that the reaction of benzaldehyde with aniline had a specificity that the phase transition occurred. In this method, the desired imines could be obtained in good to excellent yields, but target compounds had to be given by purifications using organic solvents. Therefore, we tried to develop the perfect synthetic method of imine derivatives without organic or inorganic solvents. We selected two methods and took them into this investigation. One was exactly mixing (1:1, substance ratio) aldehydes and amines and the other was employing lower pressure (>0.1 mmHg, previous method: 1.0 mmHg) at the pressure reducing technique. When this improved synthetic method was performed, it was revealed that pure target imines were obtained in excellent yields without any purification.
文摘Because imines could be used as convenient starting materials in various fields, the development of an easy synthetic method of imine was strongly desired. In response to this demand, we thought that it would be an effective synthesis method if an aldehyde and an amine could be reacted to give an imine in good yield under solvent- and catalyst-free conditions. In fact, we tried the reaction of benzaldehyde with various amines under solvent- and catalyst-free conditions followed by removal of water that was produced in the reaction system by a vacuum pump, and desired imines could be obtained in good yields. Observation of this reaction using a nuclear magnetic resonance spectrometer revealed that the reaction rate was extremely fast at the initial stage but slowed over time. However, the reaction of benzaldehyde with aniline differed greatly, and the reaction rate dramatically improved in 47 - 48 minutes after the start of the reaction. At this time, we found that the reaction system underwent a phase transition from the liquid phase to the solid phase.
文摘Alginate is a widely used polymer matrix in food industry since it allows formation of spherical, soft, and strong membranes adequate for encapsulation of a large amount of products, including food. The flow rate of alginate solutions and the permeability of the capsules were evaluated within an acidic-low acidic pH range and different alginate concentrations. In solutions adjusted at different pH （3.0 to 7.0） with concentrations of alginate of 0.8, 1.0, and 1.2% w/v, flow rates at 20 ℃ were 6.95 to 10.00, 4.54-5.35, and 2.60-2.80 mL sl, respectively. Permeability of the capsules was evaluated in terms of the diffusion of H＋ions （expressed as pH） and soluble solids （~Brix）. Meanwhile both diffusions were minor at 4.0 〈 pH 〈 7.0 and were significantly superior at more acidic pH （P 〈 0.05）, alginate concentration did not present significant effect. Yellow, purple, and red juices from Stenocereus spp. fruits （pitayas） were encapsulated using 1.0% of alginate and stored with isotonic solution （3 mL g^-1） at 4 ℃ in the dark. The capsules were spherical with diameter between 4.59 and 470 mm, weight from 82.60 to 97.50 rag, and volume of 0.075-0.098 mL. Pigment （total betalains content） diffusion reached equilibrium at 24 h of storage, at which point retentions of total betalains in the yellow, purple, and red capsules were 87.79, 96.13, and 85.13%, respectively. Also, changes in the color of the capsules were observed during storage.
