Combustion of agricultural organic solid waste(AOSW)was an ideal solution for their resource utilization in view of their massive annual production and great potential for reduction of fossil fuel utilization.However,...Combustion of agricultural organic solid waste(AOSW)was an ideal solution for their resource utilization in view of their massive annual production and great potential for reduction of fossil fuel utilization.However,high alkali and alkaline earth metals(AAEMs)content in the feedstock can arose severe fouling and slagging issues and thus prohibiting its vast utilization.In this study,a semi-continuous water washing method was proposed to preliminarily remove AAEMs from agricultural organic solid waste and its effects on the combustion behaviors of washed solid product were investigated.Results showed that the combustion index S were improved to 2.63×10-6,over 68%of the total ashes were removed from the cotton stalk,and 96.3%,89.0%and 74.7%of K,Na and Mg were effectively removed,respectively.Moreover,the softening temperature of low temperature ash from the washed sample was as high as 1450◦C,538◦C higher than the low temperature ash from the original sample;the base acid ratio and fouling index were improved from high slagging and fouling risk(1.7 and 90.8)of the original organic solid waste to low and medium risk(0.4 and 3.5),respectively.All these results signified the contributing effect of proposed semi-continuous water washing method on the combustion of agricultural organic solid waste.In a word,this study provided a promising method for fouling and slagging inhibition during the agricultural organic solid waste combustion.展开更多
Identification of waste characteristics is an important step towards improving waste recovery. The aim of this research was to determine the physical and physico-chemical characteristics of waste of Abomey–Calavi cit...Identification of waste characteristics is an important step towards improving waste recovery. The aim of this research was to determine the physical and physico-chemical characteristics of waste of Abomey–Calavi city and to study the relationship between standard of living and average ratio of daily waste generated by each person. In this study the methodology used French standards to characterize particle size and typology of solid waste generated by the population of Calavi City in Benin, West Africa. According to home criteria, the study area was stratified into three distinct levels of standard of living called: high standing, medium standing and low standing;Waste from 60 households was weighed daily. The total waste produced by each household was collected seven (7) days a week, for a period of three weeks. Waste characterization was performed using ratio, size granulometry and typological composition. Physico- Chemical analysis including organic mater, pH, Total Organic Carbon, total Kjeldahl nitrogen and metal trace element were also performed. To better assess waste compostability, water extractable organic matter was quantified and qualitative identification was made with XAD8 and XAD4 resins. Results show that the amount of waste increases with the standard of living;the average ratio of daily waste generated is 0.89 kg day-1 person-1. Independently of the standard of living, fermentable compounds represent the largest proportion of waste materials (45%). Qualitative difference of waste content in organic matter is shown as a function of the population’s living standards. These results could be explained by a higher consumption of meat in the households with a higher standard of living, reflecting a greater proportion of transphilic (TPI), and hydrophilic (HPI) fractions. The C/N ratio is lower in the high standing households than in low ones. Metal trace element analysis showed a low but still significant pollution, whereas high iron and alu minum concentrations were found in all standings. In conclusion we propose a strategy for waste management in Abomey-Calavi based on sorting at the source to eliminate plastic waste and valorization of wastes via composting.展开更多
The rapid development of nuclear technology has led to more liquid organic radioactive wastes. Different from the regular aqueous radioactive wastes, these liquids possess a higher hazard potential and cannot be dispo...The rapid development of nuclear technology has led to more liquid organic radioactive wastes. Different from the regular aqueous radioactive wastes, these liquids possess a higher hazard potential and cannot be disposed through the conventional methods due to their radioactivity and chemical nature. Spent extraction solvent is a kind of common liquid organic radioactive wastes. In this work, tri-butyl phosphate(TBP), which is more difficult to degrade in the spent extraction solvent, was used as the model compound. Influences of reaction conditions on total organic carbon(TOC) removal and the volume percentage of each gas component under supercritical water oxidation(SCWO) were studied. The SCWO behaviors of spent extraction solvent simulants were studied under the optimal conditions derived from the TBP experiment. The SCWO experiments were studied at 400–550℃, oxidant stoichiometric ratio of 0–200%, feed concentration of 1.5%–4% and pressure of25 MPa for 15–75 s. The results show that the TOC removal of the simulants was greater than 99.7% and CH4,H2 and CO were not detected at 550℃, 25 MPa, oxidant stoichiometric ratio of 150%, feed concentration of3%, and residence time of 30 s.展开更多
The effects of additional oxidants,such as NaNO_(3),Na_(2)S_(2)O_(3),KClO_(4),and K_(2)Cr_(2)O_(7),on the supercritical water oxidation(SCWO)of tributyl phosphate(TBP)were studied.The coupling of an ionic oxidant with...The effects of additional oxidants,such as NaNO_(3),Na_(2)S_(2)O_(3),KClO_(4),and K_(2)Cr_(2)O_(7),on the supercritical water oxidation(SCWO)of tributyl phosphate(TBP)were studied.The coupling of an ionic oxidant with SCWO can effectively enhance the oxidative degradation ability of the system,thus increasing its organic-matter-removal efficiency at a reduced reaction temperature.Moreover,the addition of NaNO_(3),KClO_(4),or K_(2)Cr_(2)O_(7)could improve this efficiency at a reaction temperature of 500℃compared with that of the original system at 550℃.Additionally,based on the conditions adopted in this study,the addition of either of these oxidants could reduce the final total organic carbon(TOC)of the effluent from~500 to<100 ppm.Concurrently,the ionic oxidants could effectively improve the processing capacity of the SCWO system to reduce the scale of the equipment,as well as the amount of produced wastewater.Compared with KClO_(4)and Na_(2)S_(2)O_(3),the addition of 10 mmol/L NaNO_(3)and K_(2)Cr_(2)O_(7)to the organic feed could increase the processing capacity of the system from 4 to 10%while maintaining the TOC removal at>99%.The effects of the ionic oxidants on the gas products,including CO_(2),CO,H_(2),and CH_(4),as well as other organic gases,have also been studied.Among these gas products,CO_(2)accounted for the main gas product with a proportion of more than half.At<500℃,temperature significantly affected the as products(CO,H_(2),CH_(4),and other organic gases).However,the gas product was mainly CO_(2)when the temperature was increased to≥500℃.This study initially revealed the enhancement effect of ionic oxidants on SCWO,which still requires further research.展开更多
基金the financial supports provided by the National Key Research and Development Program of China(2019YFC190252).
文摘Combustion of agricultural organic solid waste(AOSW)was an ideal solution for their resource utilization in view of their massive annual production and great potential for reduction of fossil fuel utilization.However,high alkali and alkaline earth metals(AAEMs)content in the feedstock can arose severe fouling and slagging issues and thus prohibiting its vast utilization.In this study,a semi-continuous water washing method was proposed to preliminarily remove AAEMs from agricultural organic solid waste and its effects on the combustion behaviors of washed solid product were investigated.Results showed that the combustion index S were improved to 2.63×10-6,over 68%of the total ashes were removed from the cotton stalk,and 96.3%,89.0%and 74.7%of K,Na and Mg were effectively removed,respectively.Moreover,the softening temperature of low temperature ash from the washed sample was as high as 1450◦C,538◦C higher than the low temperature ash from the original sample;the base acid ratio and fouling index were improved from high slagging and fouling risk(1.7 and 90.8)of the original organic solid waste to low and medium risk(0.4 and 3.5),respectively.All these results signified the contributing effect of proposed semi-continuous water washing method on the combustion of agricultural organic solid waste.In a word,this study provided a promising method for fouling and slagging inhibition during the agricultural organic solid waste combustion.
文摘Identification of waste characteristics is an important step towards improving waste recovery. The aim of this research was to determine the physical and physico-chemical characteristics of waste of Abomey–Calavi city and to study the relationship between standard of living and average ratio of daily waste generated by each person. In this study the methodology used French standards to characterize particle size and typology of solid waste generated by the population of Calavi City in Benin, West Africa. According to home criteria, the study area was stratified into three distinct levels of standard of living called: high standing, medium standing and low standing;Waste from 60 households was weighed daily. The total waste produced by each household was collected seven (7) days a week, for a period of three weeks. Waste characterization was performed using ratio, size granulometry and typological composition. Physico- Chemical analysis including organic mater, pH, Total Organic Carbon, total Kjeldahl nitrogen and metal trace element were also performed. To better assess waste compostability, water extractable organic matter was quantified and qualitative identification was made with XAD8 and XAD4 resins. Results show that the amount of waste increases with the standard of living;the average ratio of daily waste generated is 0.89 kg day-1 person-1. Independently of the standard of living, fermentable compounds represent the largest proportion of waste materials (45%). Qualitative difference of waste content in organic matter is shown as a function of the population’s living standards. These results could be explained by a higher consumption of meat in the households with a higher standard of living, reflecting a greater proportion of transphilic (TPI), and hydrophilic (HPI) fractions. The C/N ratio is lower in the high standing households than in low ones. Metal trace element analysis showed a low but still significant pollution, whereas high iron and alu minum concentrations were found in all standings. In conclusion we propose a strategy for waste management in Abomey-Calavi based on sorting at the source to eliminate plastic waste and valorization of wastes via composting.
基金Supported by the"Strategic Priority Research Program"of the Chinese Academy of Sciences(No.XDA02050000)
文摘The rapid development of nuclear technology has led to more liquid organic radioactive wastes. Different from the regular aqueous radioactive wastes, these liquids possess a higher hazard potential and cannot be disposed through the conventional methods due to their radioactivity and chemical nature. Spent extraction solvent is a kind of common liquid organic radioactive wastes. In this work, tri-butyl phosphate(TBP), which is more difficult to degrade in the spent extraction solvent, was used as the model compound. Influences of reaction conditions on total organic carbon(TOC) removal and the volume percentage of each gas component under supercritical water oxidation(SCWO) were studied. The SCWO behaviors of spent extraction solvent simulants were studied under the optimal conditions derived from the TBP experiment. The SCWO experiments were studied at 400–550℃, oxidant stoichiometric ratio of 0–200%, feed concentration of 1.5%–4% and pressure of25 MPa for 15–75 s. The results show that the TOC removal of the simulants was greater than 99.7% and CH4,H2 and CO were not detected at 550℃, 25 MPa, oxidant stoichiometric ratio of 150%, feed concentration of3%, and residence time of 30 s.
基金supported by the Shanghai Sail Program (No.19YF1458000)
文摘The effects of additional oxidants,such as NaNO_(3),Na_(2)S_(2)O_(3),KClO_(4),and K_(2)Cr_(2)O_(7),on the supercritical water oxidation(SCWO)of tributyl phosphate(TBP)were studied.The coupling of an ionic oxidant with SCWO can effectively enhance the oxidative degradation ability of the system,thus increasing its organic-matter-removal efficiency at a reduced reaction temperature.Moreover,the addition of NaNO_(3),KClO_(4),or K_(2)Cr_(2)O_(7)could improve this efficiency at a reaction temperature of 500℃compared with that of the original system at 550℃.Additionally,based on the conditions adopted in this study,the addition of either of these oxidants could reduce the final total organic carbon(TOC)of the effluent from~500 to<100 ppm.Concurrently,the ionic oxidants could effectively improve the processing capacity of the SCWO system to reduce the scale of the equipment,as well as the amount of produced wastewater.Compared with KClO_(4)and Na_(2)S_(2)O_(3),the addition of 10 mmol/L NaNO_(3)and K_(2)Cr_(2)O_(7)to the organic feed could increase the processing capacity of the system from 4 to 10%while maintaining the TOC removal at>99%.The effects of the ionic oxidants on the gas products,including CO_(2),CO,H_(2),and CH_(4),as well as other organic gases,have also been studied.Among these gas products,CO_(2)accounted for the main gas product with a proportion of more than half.At<500℃,temperature significantly affected the as products(CO,H_(2),CH_(4),and other organic gases).However,the gas product was mainly CO_(2)when the temperature was increased to≥500℃.This study initially revealed the enhancement effect of ionic oxidants on SCWO,which still requires further research.
