Mineral carbonation is emerging as a reliable CO_(2) capture technology that can mitigate climate change.In lime-treated clayey soils,mineral carbonation occurs through the carbonation of free lime and cementitious pr...Mineral carbonation is emerging as a reliable CO_(2) capture technology that can mitigate climate change.In lime-treated clayey soils,mineral carbonation occurs through the carbonation of free lime and cementitious products derived from pozzolanic reactions.The kinetics of the reactions in lime-treated clayey soils are variable and depend primarily on soil mineralogy.The present study demonstrates the role of soil mineralogy in CO_(2) capture and the subsequent changes caused by carbon mineralization in terms of the unconfined compressive strength(UCS)of lime-treated soils during their service life.Three clayey soils(kaolin,bentonite,and silty clay)with different mineralogical characteristics were treated with 4%lime content,and the samples were cured in a controlled environment for 7 d,90 d,180 d,and 365 d.After the specified curing periods,the samples were exposed to CO_(2) in a carbonation cell for 7 d.The non-carbonated samples purged with N2 gas were used as a benchmark to compare the mechanical,chemical-mineralogical,and microstructure changes caused by carbonation reactions.Experimental investigations indicated that exposure to CO_(2) resulted in an average increase of 10%in the UCS of limetreated bentonite,whereas the strength of lime-treated kaolin and silty clay was reduced by an average of 35%.The chemical and microstructural analyses revealed that the precipitated carbonates effectively filled the macropores of the treated bentonite,compared to the inadequate cementation caused by pozzolanic reactions,resulting in strength enhancement.In contrast,strength loss in lime-treated kaolin and silty clay was attributed to the carbonation of cementitious phases and partly to the tensile stress induced by carbonate precipitation.In terms of carbon mineralization prospects,lime-treated kaolin exhibited maximum carbonation due to the higher availability of unreacted lime.The results suggest that,in addition to the increase in compressive strength,adequate calcium-bearing phases and macropores determine the efficiency of carbon mineralization in lime-treated clayey soils.展开更多
In tropical regions,heavy rainfall induces erosion and shallow landslides on road embankments.Cement-based stabilization methods,common in these regions,contribute to climate change due to their high carbon footprint....In tropical regions,heavy rainfall induces erosion and shallow landslides on road embankments.Cement-based stabilization methods,common in these regions,contribute to climate change due to their high carbon footprint.This study explored the potential application of coir fiber-reinforced laterite soil-bottom ash mixtures as embankment materials in the tropics.The objective is to enhance engineered embankment slopes'erosion resistance and stability while offering reuse options for industrial byproducts.This study examined various mix designs for unconfined compressive strength(UCS)and permeability,utilizing 30%bottom ash(BA)and 1%coir fiber(CF)with varying sizes ranging from 10 to 40 mm,6%lime,and laterite soil(LS),followed by microstructural analyses.The results demonstrate that the compressive strength increases as the CF length increases to 25 mm.In contrast,permeability increases continuously with increasing CF length.Lime-treated mixtures exhibit superior short-and long-term strength and reduce permeability owing to the formation of cementitious materials,as confirmed by microstructural analyses.A lab-scale slope box was constructed to evaluate the surface erosion of the stabilized laterite soil embankment.Based on the rainfall simulation results,the LS-BA-CF mixtures show better resistance to erosion and deformation compared to untreated LS,especially when lime is added to the top layer.This study provides insights into a sustainable and cost-effective approach for slope stabilization using BA and CF,offering a promising solution for tropical regions susceptible to surface erosion and landslides.展开更多
The machine learning models of multiple linear regression(MLR),support vector regression(SVR),and extreme learning ma-chine(ELM)and the proposed ELM models of online sequential ELM(OS-ELM)and OS-ELM with forgetting me...The machine learning models of multiple linear regression(MLR),support vector regression(SVR),and extreme learning ma-chine(ELM)and the proposed ELM models of online sequential ELM(OS-ELM)and OS-ELM with forgetting mechanism(FOS-ELM)are applied in the prediction of the lime utilization ratio of dephosphorization in the basic oxygen furnace steelmaking process.The ELM model exhibites the best performance compared with the models of MLR and SVR.OS-ELM and FOS-ELM are applied for sequential learning and model updating.The optimal number of samples in validity term of the FOS-ELM model is determined to be 1500,with the smallest population mean absolute relative error(MARE)value of 0.058226 for the population.The variable importance analysis reveals lime weight,initial P content,and hot metal weight as the most important variables for the lime utilization ratio.The lime utilization ratio increases with the decrease in lime weight and the increases in the initial P content and hot metal weight.A prediction system based on FOS-ELM is applied in actual industrial production for one month.The hit ratios of the predicted lime utilization ratio in the error ranges of±1%,±3%,and±5%are 61.16%,90.63%,and 94.11%,respectively.The coefficient of determination,MARE,and root mean square error are 0.8670,0.06823,and 1.4265,respectively.The system exhibits desirable performance for applications in actual industrial pro-duction.展开更多
This paper presents and analyzes the results of a series of compaction,fragmentability and damage tests performed on an expansive overconsolidated clay treated with cement and lime.This clay was obtained from the urba...This paper presents and analyzes the results of a series of compaction,fragmentability and damage tests performed on an expansive overconsolidated clay treated with cement and lime.This clay was obtained from the urban site of Sidi-Hadjrès city(wilaya of M'sila,Algeria),where significant damages frequently appears in the road infrastructures,roadway systems and light structures.Tests results obtained show that the geotechnical parameters values deduced from these tests are concordant and confirm the evolutivity of this natural clay treated with composed Portland cement or extinct lime and compacted under optimum Proctor conditions.展开更多
The aim of this study was to evaluate the compressive strength of clay bricks and their stability to water absorption by inserting stabilizers such as lime and cement of 0%, 4%, 6%, 8%, 10%, 12% to 14%. Spectrometric ...The aim of this study was to evaluate the compressive strength of clay bricks and their stability to water absorption by inserting stabilizers such as lime and cement of 0%, 4%, 6%, 8%, 10%, 12% to 14%. Spectrometric analysis was used to characterize the various stabilizers and the clay used, and tests of resistance and water absorption were also carried out. The clay was found to be an aluminosilicate (15.55% to 17.17% Al2O3 and 42.12% to 44.15% SiO2). The lime contains 90.84% CaO and the cement has 17.80% SiO2, 3.46% Al2O3, 2.43% Fe2O3 and 58.47% CaO in the combined form of tricalcium silicate, dicalcium silicate, tricalcium aluminate and ferro-tetra calcium aluminate. The results showed that the insertion of locally available stabilizers (lime and cement) improved the strength of the material by almost 80% when the lime was increased from 0% to 14% for 14 days. For compressed cement, a 65% increase in strength was observed under the same conditions. Strength increases with drying time, with a 52% increase in strength at 28 days compared to 14 days. Furthermore, compressed cement bricks have a more compact structure, absorbing very little water (32%). In view of all these results, cement appears to be the best stabilizer, and compression improves compressive strength and reduces water absorption.展开更多
Agricultural liming contributes significantly to atmospheric CO2 emission from soils but data on magnitude of lime- contributed CO2 in a wide range of acid soils are still few. Data on lime-contributed CO2 and SOC tur...Agricultural liming contributes significantly to atmospheric CO2 emission from soils but data on magnitude of lime- contributed CO2 in a wide range of acid soils are still few. Data on lime-contributed CO2 and SOC turnover for global acid soils are needed to estimate the potential contribution of agricultural liming to atmospheric CO2. Using Ca13CO3 (13C 99%) as lime and tracer, here we separated lime-contributed and SOC-originated CO2 evolution in an acidic Kuroboku Andisol from Tanashi, Tokyo Prefecture (35°44′ N, 139°32′ E) and Kunigami Mahji Ultisol of Nakijin, Okinawa Prefecture, Japan (26°38′ N, 127°58′ E). On the average, lime-CO2 was 76.84% (Kuroboku Andisol) and 66.36% (Kunigami Mahji Ultisol) of overall CO2 emission after 36 days. There was increased SOC turnover in all limed soils, confirming priming effect (PE) of liming. The calculated PE of lime (Kuroboku Andisol, 51.97% - 114.95%;Kunigami Mahji Ultisol, 10.13% - 35.61%) was entirely 12C turnover of stable soil organic carbon (SOC) since SMBC, a labile SOC pool, was suppressed by liming in our experiment. Our results confirmed that mineralization of lime-carbonates is the major source of CO2 emission from acid soils during agricultural liming. Liming can influence the size of CO2 evolution from agricultural ecosystems considering global extent of acid soils and current volume of lime utilization. We propose the inclusion of liming in simulating carbon dynamics in agricultural ecosystems.展开更多
Two field experiments were conducted in the main seasons of 2021/22 at the farmers'farm in two districts of southwest Ethiopia to investigate the effects of lime and phosphorus on groundnut yield and yield compone...Two field experiments were conducted in the main seasons of 2021/22 at the farmers'farm in two districts of southwest Ethiopia to investigate the effects of lime and phosphorus on groundnut yield and yield components,employing four levels of lime(0,2,4,and 6 t CaCO_(3)ha^(-1))and phosphorus(0,46,69,and 92 kg P_(2)O_(5)ha^(-1))arranged in factorial RCBD design with three replications.Data on the yield and its components were collected and subjected to an ANOVA using SAS software.The result demonstrated that plant height,number of branches,canopy spread,and shelling percentage were affected significantly by liming while effective nodule number,total peg,matured pod,and pod yield of groundnut significantly influenced by the main factors and their interactions.The combined application of 4 t lime and 46 kg P_(2)O_(5)ha^(-1)resulted in the highest number of effective nodules(147.23 plant^(-1)),total pod(72.6 plant^(-1)),mature pod(62.4 plant^(-1)),pod yield(4.49 t ha^(-1)),oil content(50.6%)and protein content(33.1%)whereas the lowest values of these parameters were seen in plots where neither lime nor phosphorus was applied.Therefore,it is advised that groundnut growers in the study areas,and similar agroecologies,apply the combination of 4 t lime and 46 kg P_(2)O_(5)ha^(-1).展开更多
In this paper the use of lime stabilized subgrade for low volume roads in two regions with high mountains and different frost penetration conditions in Türkiye was investigated in terms of design,performance,and ...In this paper the use of lime stabilized subgrade for low volume roads in two regions with high mountains and different frost penetration conditions in Türkiye was investigated in terms of design,performance,and cost.Pavements on unstabilized and stabilized subgrade were designed for two regions(Izmir and Van),covering all climate variations.The resilient modulus of the lime stabilized subgrade with different soil pulverization levels for non-freezing and freezing conditions were taken from a previous laboratory study.Frost effects were considered in pavement design using two different approaches,including limited subgrade frost penetration method and reduced subgrade strength method.Detailed application and evaluation were performed for all steps.Lime stabilized subgrades significantly reduced the thickness of base courses,and the benefit of lime stabilization was highly dependent on soil pulverization level.A detailed cost analysis on the unstabilized and stabilized cases found that the use of lime stabilization in the subgrade provided significant initial cost savings.Comparative analysis by using the AASHTO(1993)method and KENPAVE software,and quantity effect of soil pulverization level on the performance of low volume roads from a service life perspective,show that subgrade resilient modulus can be estimated.It is also possible to make correct performance estimation in the field.The results of the study show that lime stabilization is a good solution for low volume roads in the mountainous regions of Türkiye.展开更多
The main objective of the study is to improve the removal efficiency of Ourlago-kaolin (Kao), sodium montmorillonite (Na-MMT), and two formulated clay-lime (F13 and F23) towards CI Acid Orange 52 dye (AO52). F13 and F...The main objective of the study is to improve the removal efficiency of Ourlago-kaolin (Kao), sodium montmorillonite (Na-MMT), and two formulated clay-lime (F13 and F23) towards CI Acid Orange 52 dye (AO52). F13 and F23 were obtained by chemical stabilization through thermal treatment at 300°C. Fourier Transform Infrared spectra showed different surface functional groups on the clay materials, X-ray diffraction patterns revealed the raw materials contain many crystalline phases, scanning electron microscopy micrographs showed the variation of the layered structures of different clay materials, energy dispersive X-Ray analysis micrographs revealed compositional information and thermogravimetric-differential scanning calorimetry curves indicated the higher weight loss of 11.26% and 11.38% were observed for F13 and F23 respectively. BET surface area analyzed gave 133.0071 m<sup>2</sup>•g<sup>−1</sup> for F13 and 132.34803 m<sup>2</sup>•g<sup>−1</sup> for F23. The optimum pH value was 2.0 for Kao and Na-MMT. The adsorption experiments indicated that F13 and F23 have the maximum uptake abilities of 7.8740 and 3.1645 mg•g<sup>−1</sup>, respectively, compared to Kao (0.8761 mg•g<sup>−1</sup>) and Na-MMT (2.6178 mg•g<sup>−1</sup>). The pseudo-second-order model well described the adsorption kinetic model of AO52 dye onto the overall samples;Langmuir and Freundlich’s isotherms appropriately described the uptake mechanism. The positive values of ∆G° and negative value ∆H° indicated that the adsorption process was spontaneous and endothermic for Na-MMT, and non-spontaneous and exothermic for Kao, F13, and F23 because of their positive values of ∆G° and negative value of ∆H°. The modified clays have higher adsorption capacities and better life cycles compared hence opening new avenues for efficient wastewater treatment.展开更多
Thermal alkaline hydrolysis is a common pretreatment method for the utilization of excess activated sludge(EAS).Owing to strict environment laws and need for better energy utilization,new methods were developed in thi...Thermal alkaline hydrolysis is a common pretreatment method for the utilization of excess activated sludge(EAS).Owing to strict environment laws and need for better energy utilization,new methods were developed in this study to improve the efficiency of pretreatment method.Direct thermal hydrolysis(TH),pasteurized thermal hydrolysis(PTH),and alkaline pasteurized thermal hydrolysis(PTH+CaO and PTH+NaOH)methods were used to treat EAS.Each method was compared and analyzed in terms of dissolution in ammonium nitrogen(NH_(4)^(+)-N)and soluble COD(SCOD)in EAS.Furthermore,the removal of tetracycline resistance genes(TRGs)and class 1 transposon gene intI1 from EAS was investigated.The NH_(4)^(+)-N and SCOD concentrations in EAS treated by PTH were 1.24 and 2.58 times higher than those of TH.However,the removal efficiency of total TRGs and intI1 between the groups was comparable.The SCOD concentration of the PTH+NaOH group was 4.37 times higher than that of the PTH group,and the removal efficiency of total TRGs was increased by 9.52%compared with that by PTH.The NH_(4)^(+)-N and SCOD concentrations of the PTH+CaO group could reach 85.04%and 92.14%of the PTH+NaOH group,but the removal efficiency of total TRGs by PTH+CaO was 19.78%lower than that by PTH+NaOH.Thus,to reduce the financial cost in actual operation,lime(CaO)can be used instead of a strong alkali(NaOH),and pasteurized steam at 70℃ instead of conventional high-temperature heating to treat EAS.This study provides a reference for the development of alkaline hydrolysis under moderate temperatures along with the removal of TRGs in EAS.展开更多
基金partial financial support by the Women Leading IITM,IIT Madras,Chennai,India.
文摘Mineral carbonation is emerging as a reliable CO_(2) capture technology that can mitigate climate change.In lime-treated clayey soils,mineral carbonation occurs through the carbonation of free lime and cementitious products derived from pozzolanic reactions.The kinetics of the reactions in lime-treated clayey soils are variable and depend primarily on soil mineralogy.The present study demonstrates the role of soil mineralogy in CO_(2) capture and the subsequent changes caused by carbon mineralization in terms of the unconfined compressive strength(UCS)of lime-treated soils during their service life.Three clayey soils(kaolin,bentonite,and silty clay)with different mineralogical characteristics were treated with 4%lime content,and the samples were cured in a controlled environment for 7 d,90 d,180 d,and 365 d.After the specified curing periods,the samples were exposed to CO_(2) in a carbonation cell for 7 d.The non-carbonated samples purged with N2 gas were used as a benchmark to compare the mechanical,chemical-mineralogical,and microstructure changes caused by carbonation reactions.Experimental investigations indicated that exposure to CO_(2) resulted in an average increase of 10%in the UCS of limetreated bentonite,whereas the strength of lime-treated kaolin and silty clay was reduced by an average of 35%.The chemical and microstructural analyses revealed that the precipitated carbonates effectively filled the macropores of the treated bentonite,compared to the inadequate cementation caused by pozzolanic reactions,resulting in strength enhancement.In contrast,strength loss in lime-treated kaolin and silty clay was attributed to the carbonation of cementitious phases and partly to the tensile stress induced by carbonate precipitation.In terms of carbon mineralization prospects,lime-treated kaolin exhibited maximum carbonation due to the higher availability of unreacted lime.The results suggest that,in addition to the increase in compressive strength,adequate calcium-bearing phases and macropores determine the efficiency of carbon mineralization in lime-treated clayey soils.
文摘In tropical regions,heavy rainfall induces erosion and shallow landslides on road embankments.Cement-based stabilization methods,common in these regions,contribute to climate change due to their high carbon footprint.This study explored the potential application of coir fiber-reinforced laterite soil-bottom ash mixtures as embankment materials in the tropics.The objective is to enhance engineered embankment slopes'erosion resistance and stability while offering reuse options for industrial byproducts.This study examined various mix designs for unconfined compressive strength(UCS)and permeability,utilizing 30%bottom ash(BA)and 1%coir fiber(CF)with varying sizes ranging from 10 to 40 mm,6%lime,and laterite soil(LS),followed by microstructural analyses.The results demonstrate that the compressive strength increases as the CF length increases to 25 mm.In contrast,permeability increases continuously with increasing CF length.Lime-treated mixtures exhibit superior short-and long-term strength and reduce permeability owing to the formation of cementitious materials,as confirmed by microstructural analyses.A lab-scale slope box was constructed to evaluate the surface erosion of the stabilized laterite soil embankment.Based on the rainfall simulation results,the LS-BA-CF mixtures show better resistance to erosion and deformation compared to untreated LS,especially when lime is added to the top layer.This study provides insights into a sustainable and cost-effective approach for slope stabilization using BA and CF,offering a promising solution for tropical regions susceptible to surface erosion and landslides.
基金supported by the National Natural Science Foundation of China (No.U1960202).
文摘The machine learning models of multiple linear regression(MLR),support vector regression(SVR),and extreme learning ma-chine(ELM)and the proposed ELM models of online sequential ELM(OS-ELM)and OS-ELM with forgetting mechanism(FOS-ELM)are applied in the prediction of the lime utilization ratio of dephosphorization in the basic oxygen furnace steelmaking process.The ELM model exhibites the best performance compared with the models of MLR and SVR.OS-ELM and FOS-ELM are applied for sequential learning and model updating.The optimal number of samples in validity term of the FOS-ELM model is determined to be 1500,with the smallest population mean absolute relative error(MARE)value of 0.058226 for the population.The variable importance analysis reveals lime weight,initial P content,and hot metal weight as the most important variables for the lime utilization ratio.The lime utilization ratio increases with the decrease in lime weight and the increases in the initial P content and hot metal weight.A prediction system based on FOS-ELM is applied in actual industrial production for one month.The hit ratios of the predicted lime utilization ratio in the error ranges of±1%,±3%,and±5%are 61.16%,90.63%,and 94.11%,respectively.The coefficient of determination,MARE,and root mean square error are 0.8670,0.06823,and 1.4265,respectively.The system exhibits desirable performance for applications in actual industrial pro-duction.
文摘This paper presents and analyzes the results of a series of compaction,fragmentability and damage tests performed on an expansive overconsolidated clay treated with cement and lime.This clay was obtained from the urban site of Sidi-Hadjrès city(wilaya of M'sila,Algeria),where significant damages frequently appears in the road infrastructures,roadway systems and light structures.Tests results obtained show that the geotechnical parameters values deduced from these tests are concordant and confirm the evolutivity of this natural clay treated with composed Portland cement or extinct lime and compacted under optimum Proctor conditions.
文摘The aim of this study was to evaluate the compressive strength of clay bricks and their stability to water absorption by inserting stabilizers such as lime and cement of 0%, 4%, 6%, 8%, 10%, 12% to 14%. Spectrometric analysis was used to characterize the various stabilizers and the clay used, and tests of resistance and water absorption were also carried out. The clay was found to be an aluminosilicate (15.55% to 17.17% Al2O3 and 42.12% to 44.15% SiO2). The lime contains 90.84% CaO and the cement has 17.80% SiO2, 3.46% Al2O3, 2.43% Fe2O3 and 58.47% CaO in the combined form of tricalcium silicate, dicalcium silicate, tricalcium aluminate and ferro-tetra calcium aluminate. The results showed that the insertion of locally available stabilizers (lime and cement) improved the strength of the material by almost 80% when the lime was increased from 0% to 14% for 14 days. For compressed cement, a 65% increase in strength was observed under the same conditions. Strength increases with drying time, with a 52% increase in strength at 28 days compared to 14 days. Furthermore, compressed cement bricks have a more compact structure, absorbing very little water (32%). In view of all these results, cement appears to be the best stabilizer, and compression improves compressive strength and reduces water absorption.
文摘Agricultural liming contributes significantly to atmospheric CO2 emission from soils but data on magnitude of lime- contributed CO2 in a wide range of acid soils are still few. Data on lime-contributed CO2 and SOC turnover for global acid soils are needed to estimate the potential contribution of agricultural liming to atmospheric CO2. Using Ca13CO3 (13C 99%) as lime and tracer, here we separated lime-contributed and SOC-originated CO2 evolution in an acidic Kuroboku Andisol from Tanashi, Tokyo Prefecture (35°44′ N, 139°32′ E) and Kunigami Mahji Ultisol of Nakijin, Okinawa Prefecture, Japan (26°38′ N, 127°58′ E). On the average, lime-CO2 was 76.84% (Kuroboku Andisol) and 66.36% (Kunigami Mahji Ultisol) of overall CO2 emission after 36 days. There was increased SOC turnover in all limed soils, confirming priming effect (PE) of liming. The calculated PE of lime (Kuroboku Andisol, 51.97% - 114.95%;Kunigami Mahji Ultisol, 10.13% - 35.61%) was entirely 12C turnover of stable soil organic carbon (SOC) since SMBC, a labile SOC pool, was suppressed by liming in our experiment. Our results confirmed that mineralization of lime-carbonates is the major source of CO2 emission from acid soils during agricultural liming. Liming can influence the size of CO2 evolution from agricultural ecosystems considering global extent of acid soils and current volume of lime utilization. We propose the inclusion of liming in simulating carbon dynamics in agricultural ecosystems.
基金Mattu University Research Affairs directorate and Mattu University Bedele Campus research coordination office for their administrative and financial support.
文摘Two field experiments were conducted in the main seasons of 2021/22 at the farmers'farm in two districts of southwest Ethiopia to investigate the effects of lime and phosphorus on groundnut yield and yield components,employing four levels of lime(0,2,4,and 6 t CaCO_(3)ha^(-1))and phosphorus(0,46,69,and 92 kg P_(2)O_(5)ha^(-1))arranged in factorial RCBD design with three replications.Data on the yield and its components were collected and subjected to an ANOVA using SAS software.The result demonstrated that plant height,number of branches,canopy spread,and shelling percentage were affected significantly by liming while effective nodule number,total peg,matured pod,and pod yield of groundnut significantly influenced by the main factors and their interactions.The combined application of 4 t lime and 46 kg P_(2)O_(5)ha^(-1)resulted in the highest number of effective nodules(147.23 plant^(-1)),total pod(72.6 plant^(-1)),mature pod(62.4 plant^(-1)),pod yield(4.49 t ha^(-1)),oil content(50.6%)and protein content(33.1%)whereas the lowest values of these parameters were seen in plots where neither lime nor phosphorus was applied.Therefore,it is advised that groundnut growers in the study areas,and similar agroecologies,apply the combination of 4 t lime and 46 kg P_(2)O_(5)ha^(-1).
基金a joint venture project between Istanbul University and the Turkish General Directorate of Highways by project number KGM-ARGE/2012-25funded by Istanbul University-Cerrahpasa Scientific Research Projects under Project No:ACIP 54739。
文摘In this paper the use of lime stabilized subgrade for low volume roads in two regions with high mountains and different frost penetration conditions in Türkiye was investigated in terms of design,performance,and cost.Pavements on unstabilized and stabilized subgrade were designed for two regions(Izmir and Van),covering all climate variations.The resilient modulus of the lime stabilized subgrade with different soil pulverization levels for non-freezing and freezing conditions were taken from a previous laboratory study.Frost effects were considered in pavement design using two different approaches,including limited subgrade frost penetration method and reduced subgrade strength method.Detailed application and evaluation were performed for all steps.Lime stabilized subgrades significantly reduced the thickness of base courses,and the benefit of lime stabilization was highly dependent on soil pulverization level.A detailed cost analysis on the unstabilized and stabilized cases found that the use of lime stabilization in the subgrade provided significant initial cost savings.Comparative analysis by using the AASHTO(1993)method and KENPAVE software,and quantity effect of soil pulverization level on the performance of low volume roads from a service life perspective,show that subgrade resilient modulus can be estimated.It is also possible to make correct performance estimation in the field.The results of the study show that lime stabilization is a good solution for low volume roads in the mountainous regions of Türkiye.
文摘The main objective of the study is to improve the removal efficiency of Ourlago-kaolin (Kao), sodium montmorillonite (Na-MMT), and two formulated clay-lime (F13 and F23) towards CI Acid Orange 52 dye (AO52). F13 and F23 were obtained by chemical stabilization through thermal treatment at 300°C. Fourier Transform Infrared spectra showed different surface functional groups on the clay materials, X-ray diffraction patterns revealed the raw materials contain many crystalline phases, scanning electron microscopy micrographs showed the variation of the layered structures of different clay materials, energy dispersive X-Ray analysis micrographs revealed compositional information and thermogravimetric-differential scanning calorimetry curves indicated the higher weight loss of 11.26% and 11.38% were observed for F13 and F23 respectively. BET surface area analyzed gave 133.0071 m<sup>2</sup>•g<sup>−1</sup> for F13 and 132.34803 m<sup>2</sup>•g<sup>−1</sup> for F23. The optimum pH value was 2.0 for Kao and Na-MMT. The adsorption experiments indicated that F13 and F23 have the maximum uptake abilities of 7.8740 and 3.1645 mg•g<sup>−1</sup>, respectively, compared to Kao (0.8761 mg•g<sup>−1</sup>) and Na-MMT (2.6178 mg•g<sup>−1</sup>). The pseudo-second-order model well described the adsorption kinetic model of AO52 dye onto the overall samples;Langmuir and Freundlich’s isotherms appropriately described the uptake mechanism. The positive values of ∆G° and negative value ∆H° indicated that the adsorption process was spontaneous and endothermic for Na-MMT, and non-spontaneous and exothermic for Kao, F13, and F23 because of their positive values of ∆G° and negative value of ∆H°. The modified clays have higher adsorption capacities and better life cycles compared hence opening new avenues for efficient wastewater treatment.
基金supported by the Key R&D Projects of the Sichuan Provincial Department of Science and Technology in 2022 (No.2022YFS0457)Innovation and Entrepreneurship Training Program for College Students (No.202210649050).
文摘Thermal alkaline hydrolysis is a common pretreatment method for the utilization of excess activated sludge(EAS).Owing to strict environment laws and need for better energy utilization,new methods were developed in this study to improve the efficiency of pretreatment method.Direct thermal hydrolysis(TH),pasteurized thermal hydrolysis(PTH),and alkaline pasteurized thermal hydrolysis(PTH+CaO and PTH+NaOH)methods were used to treat EAS.Each method was compared and analyzed in terms of dissolution in ammonium nitrogen(NH_(4)^(+)-N)and soluble COD(SCOD)in EAS.Furthermore,the removal of tetracycline resistance genes(TRGs)and class 1 transposon gene intI1 from EAS was investigated.The NH_(4)^(+)-N and SCOD concentrations in EAS treated by PTH were 1.24 and 2.58 times higher than those of TH.However,the removal efficiency of total TRGs and intI1 between the groups was comparable.The SCOD concentration of the PTH+NaOH group was 4.37 times higher than that of the PTH group,and the removal efficiency of total TRGs was increased by 9.52%compared with that by PTH.The NH_(4)^(+)-N and SCOD concentrations of the PTH+CaO group could reach 85.04%and 92.14%of the PTH+NaOH group,but the removal efficiency of total TRGs by PTH+CaO was 19.78%lower than that by PTH+NaOH.Thus,to reduce the financial cost in actual operation,lime(CaO)can be used instead of a strong alkali(NaOH),and pasteurized steam at 70℃ instead of conventional high-temperature heating to treat EAS.This study provides a reference for the development of alkaline hydrolysis under moderate temperatures along with the removal of TRGs in EAS.