Shortcut nitrification for ammonium-rich wastewater is energy-saving and cost-effective procedure that has become one of the hotspots in the field of biological denitrogenation. An orthogonal experiment was performed ...Shortcut nitrification for ammonium-rich wastewater is energy-saving and cost-effective procedure that has become one of the hotspots in the field of biological denitrogenation. An orthogonal experiment was performed to study the combined effects of operational parameters on the performance of internal-loop airlift bioreactor for shortcut nitrification. The optimum operational parameters for the shortcut nitrification were fotmd as temperature 35 ℃, pH 8.0, dissolved oxygen concentration 1.0 mg/L, ammonium concentration 4 mmol/L and HRT 16 h, which have different influence on the performance of shortcut nitrification reactor. The pH, temperature and dissolved oxygen concentration have significant bearing on the process. The results showed that the shortcut nitrification reactor could be successfully started up within 42 d, and the reactor performance is steady with minimum NO2-/NOx- of 85.2%, maximum 93.4% and average value of 91.4% in effluent. Based on the analysis of experimental data, a new control strategy named “priority ＋ combination” for shortcut nitrification was suggested. Through this strategy, the startup and operation of shortcut nitrification for ammonium-rich sludge digester liquids were optimized. The control strategy works well to keep the reactor operation in steady state and in achieving high-efficiency for shortcut nitrification.展开更多
采用正交表头L16(4^3×2^6)设计正交实验,优化了一种适用于同时测定烟用有机肥中总氮、总磷、总钾含量的样品消解仪方法。实验考察了三个因子:称样量、冲洗水体积、硫酸体积,每个因子各四水平的实验条件。经过直观分析发现:称样量...采用正交表头L16(4^3×2^6)设计正交实验,优化了一种适用于同时测定烟用有机肥中总氮、总磷、总钾含量的样品消解仪方法。实验考察了三个因子:称样量、冲洗水体积、硫酸体积,每个因子各四水平的实验条件。经过直观分析发现:称样量对钾的测定结果影响较大,故取钾测定时消化条件中称样量的最佳条件,即0.4 g,而冲洗水体积和H2SO4体积对总氮、总磷、钾测定结果的影响都不大。本着尽量淹没样品、节约试剂的原则,冲洗水和H2SO4的体积均选择4 m L。展开更多
S<span>everal challenges are associated </span></span><span style="font-family:"">with</span><span style="font-family:""> the development, adoption and...S<span>everal challenges are associated </span></span><span style="font-family:"">with</span><span style="font-family:""> the development, adoption and de</span><span style="font-family:"">ployment of biogas digesters in developing countries. Amongst these challenges is a comprehensive and systematic procedure for the design of digesters suitable for rural communities. This paper proposes the Flexible Biogas Digester System (FBDS) as a viable option for rural communities in developing countries and provide</span><span style="font-family:"">s</span><span style="font-family:""> a detailed step-by-step procedure for it</span><span style="font-family:"">s</span><span style="font-family:""> design. The biogas production process is a function of the digester operating factors which may be grouped into physical, process and performance parameters. The physical design parameters include</span><span style="font-family:""> </span><span style="font-family:"">the digester volume, the volume of the biogas storage tank, and the volume of the installation pit. The process parameters include total solid content of the slurry (TS), organic loading rate (OLR), digester operating temperatures, pH of the slurry inside the digester. The performance parameters include</span><span style="font-family:""> </span><span style="font-family:"">biogas production rate, biogas productivity and biogas quality. The Net Present Value and the Levelised Cost of Energy are presented for simple economic evaluation of the FBDS.展开更多
A domestic balloon-type digester with 1200 liters of substrate and a 700-litre gas reserve was installed at the Université Gaston Berger pilot farm, which has 4 cows. After an initial load of 1000 L of water, 90 ...A domestic balloon-type digester with 1200 liters of substrate and a 700-litre gas reserve was installed at the Université Gaston Berger pilot farm, which has 4 cows. After an initial load of 1000 L of water, 90 L of bovine rumen and 145 L of cow dung, the functional parameters of the reaction medium, i.e., temperature, pH, salinity and conductimetry, were regularly monitored at a rate of 3 tests per day until the thirtieth day, corresponding to the flame test and the start of analysis and daily loading of the biodigester. The analysis of the biogas obtained after the flame test showed us the considerable contribution of bovine hindquarters to the CH4 fraction, which reached 72.2% from the start of the production phase. As anaerobic digestion is both a complex and multiparametric process, microbiological analysis revealed the presence of several strains of bacteria in the substrate used. Among the most abundant were Escherichia coli, Klebsiella spp, non-fermentative Gram-negative bacilli and Enterococcus sp. However, the bacterial strain that interests us most in anaerobic digestion is the non-fermentative Gram-negative family. We see the identification and temporal monitoring of these families of bacteria as a major step forward in the control of anaerobic fermentation processes in the Sahelian context and in Senegal in particular.展开更多
Pulping production process produces a large amount of wastewater and pollutant emitted, which has become one of the main pollution sources in pulp and paper industry. To solve this problem, it is necessary to implemen...Pulping production process produces a large amount of wastewater and pollutant emitted, which has become one of the main pollution sources in pulp and paper industry. To solve this problem, it is necessary to implement cleaner production by using modeling and optimization technology. This paper studies the modeling and multi\|objective genetic algorithms for continuous digester process. First, model is established, in which environmental pollution and saving energy factors are considered. Then hybrid genetic algorithm based on Pareto stratum\|niche count is designed for finding near\|Pareto or Pareto optimal solutions in the problem and a new genetic evaluation and selection mechanism is proposed. Finally using the real data from a pulp mill shows the results of computer simulation. Through comparing with the practical curve of digester,this method can reduce the pollutant effectively and increase the profit while keeping the pulp quality unchanged.展开更多
The quality of the resulting pulping continuous digesters is monitored by measuring the Kappa number, which is a reference of residual lignin. The control of the kappa number is carried out mainly in the top of the di...The quality of the resulting pulping continuous digesters is monitored by measuring the Kappa number, which is a reference of residual lignin. The control of the kappa number is carried out mainly in the top of the digester, therefore it is important to get some indication of this analysis beforehand. In this context, the aim of this work was to obtain a prediction model of the kappa number in advance to the laboratory results. This paper proposes a new approach using the Box & Jenkins methodology to develop a dynamic model for predicting the kappa number from a Kamyr continuous digester from an eucalyptus Kraft pulp mill in Brazil. With a database of 1500 observations over a period of 30 days of operation, some ARMA models were studied, leading to the choice of ARMA (1, 2) as the best forecasting model. After fitting the model, we performed validation with a new set of data from 30 days of operation, achieving a model of 2.7% mean absolute percent error.展开更多
Ammonia recovery from wastewater is crucial,yet technology of low carbon emission and high ammonia perm-selectivity against complex stream compositions is urgently needed.Herein,a membrane-based hybrid process of the ...Ammonia recovery from wastewater is crucial,yet technology of low carbon emission and high ammonia perm-selectivity against complex stream compositions is urgently needed.Herein,a membrane-based hybrid process of the Donnan dialysiseelectrodialysis process(DDeED)was proposed for sustainable and efficient ammonia recovery.In principle,DD removes the majority of ammonia in wastewater by exploring the concentration gradient of NH4 t and driven cation(Nat)across the cation exchange membrane,given industrial sodium salt as a driving chemical.An additional ED stage driven by solar energy realizes a further removal of ammonia,recovery of driven cation,and replenishment of OHtoward ammonia stripping.Our results demonstrated that the hybrid DDeED process achieved ammonia removal efficiency>95%,driving cation(Nat)recovery efficiency>87.1%for synthetic streams,and reduced the OH-loss by up to 78%compared to a standalone DD case.Ammonia fluxes of 98.2 gN m^(-2)d^(-1)with the real anaerobic digestion effluent were observed using only solar energy input at 3.8 kWh kgN^(-1).With verified mass transfer modeling,reasonably controlled operation,and beneficial recovery performance,the hybrid process can be a promising candidate for future nutrient recovery from wastewater in a rural,remote area.展开更多
文摘Shortcut nitrification for ammonium-rich wastewater is energy-saving and cost-effective procedure that has become one of the hotspots in the field of biological denitrogenation. An orthogonal experiment was performed to study the combined effects of operational parameters on the performance of internal-loop airlift bioreactor for shortcut nitrification. The optimum operational parameters for the shortcut nitrification were fotmd as temperature 35 ℃, pH 8.0, dissolved oxygen concentration 1.0 mg/L, ammonium concentration 4 mmol/L and HRT 16 h, which have different influence on the performance of shortcut nitrification reactor. The pH, temperature and dissolved oxygen concentration have significant bearing on the process. The results showed that the shortcut nitrification reactor could be successfully started up within 42 d, and the reactor performance is steady with minimum NO2-/NOx- of 85.2%, maximum 93.4% and average value of 91.4% in effluent. Based on the analysis of experimental data, a new control strategy named “priority ＋ combination” for shortcut nitrification was suggested. Through this strategy, the startup and operation of shortcut nitrification for ammonium-rich sludge digester liquids were optimized. The control strategy works well to keep the reactor operation in steady state and in achieving high-efficiency for shortcut nitrification.
文摘采用正交表头L16(4^3×2^6)设计正交实验,优化了一种适用于同时测定烟用有机肥中总氮、总磷、总钾含量的样品消解仪方法。实验考察了三个因子:称样量、冲洗水体积、硫酸体积,每个因子各四水平的实验条件。经过直观分析发现:称样量对钾的测定结果影响较大,故取钾测定时消化条件中称样量的最佳条件,即0.4 g,而冲洗水体积和H2SO4体积对总氮、总磷、钾测定结果的影响都不大。本着尽量淹没样品、节约试剂的原则,冲洗水和H2SO4的体积均选择4 m L。
文摘S<span>everal challenges are associated </span></span><span style="font-family:"">with</span><span style="font-family:""> the development, adoption and de</span><span style="font-family:"">ployment of biogas digesters in developing countries. Amongst these challenges is a comprehensive and systematic procedure for the design of digesters suitable for rural communities. This paper proposes the Flexible Biogas Digester System (FBDS) as a viable option for rural communities in developing countries and provide</span><span style="font-family:"">s</span><span style="font-family:""> a detailed step-by-step procedure for it</span><span style="font-family:"">s</span><span style="font-family:""> design. The biogas production process is a function of the digester operating factors which may be grouped into physical, process and performance parameters. The physical design parameters include</span><span style="font-family:""> </span><span style="font-family:"">the digester volume, the volume of the biogas storage tank, and the volume of the installation pit. The process parameters include total solid content of the slurry (TS), organic loading rate (OLR), digester operating temperatures, pH of the slurry inside the digester. The performance parameters include</span><span style="font-family:""> </span><span style="font-family:"">biogas production rate, biogas productivity and biogas quality. The Net Present Value and the Levelised Cost of Energy are presented for simple economic evaluation of the FBDS.
文摘A domestic balloon-type digester with 1200 liters of substrate and a 700-litre gas reserve was installed at the Université Gaston Berger pilot farm, which has 4 cows. After an initial load of 1000 L of water, 90 L of bovine rumen and 145 L of cow dung, the functional parameters of the reaction medium, i.e., temperature, pH, salinity and conductimetry, were regularly monitored at a rate of 3 tests per day until the thirtieth day, corresponding to the flame test and the start of analysis and daily loading of the biodigester. The analysis of the biogas obtained after the flame test showed us the considerable contribution of bovine hindquarters to the CH4 fraction, which reached 72.2% from the start of the production phase. As anaerobic digestion is both a complex and multiparametric process, microbiological analysis revealed the presence of several strains of bacteria in the substrate used. Among the most abundant were Escherichia coli, Klebsiella spp, non-fermentative Gram-negative bacilli and Enterococcus sp. However, the bacterial strain that interests us most in anaerobic digestion is the non-fermentative Gram-negative family. We see the identification and temporal monitoring of these families of bacteria as a major step forward in the control of anaerobic fermentation processes in the Sahelian context and in Senegal in particular.
基金TheNationNaturalScienceFoundationofChina (No .6 9974 0 34)
文摘Pulping production process produces a large amount of wastewater and pollutant emitted, which has become one of the main pollution sources in pulp and paper industry. To solve this problem, it is necessary to implement cleaner production by using modeling and optimization technology. This paper studies the modeling and multi\|objective genetic algorithms for continuous digester process. First, model is established, in which environmental pollution and saving energy factors are considered. Then hybrid genetic algorithm based on Pareto stratum\|niche count is designed for finding near\|Pareto or Pareto optimal solutions in the problem and a new genetic evaluation and selection mechanism is proposed. Finally using the real data from a pulp mill shows the results of computer simulation. Through comparing with the practical curve of digester,this method can reduce the pollutant effectively and increase the profit while keeping the pulp quality unchanged.
文摘The quality of the resulting pulping continuous digesters is monitored by measuring the Kappa number, which is a reference of residual lignin. The control of the kappa number is carried out mainly in the top of the digester, therefore it is important to get some indication of this analysis beforehand. In this context, the aim of this work was to obtain a prediction model of the kappa number in advance to the laboratory results. This paper proposes a new approach using the Box & Jenkins methodology to develop a dynamic model for predicting the kappa number from a Kamyr continuous digester from an eucalyptus Kraft pulp mill in Brazil. With a database of 1500 observations over a period of 30 days of operation, some ARMA models were studied, leading to the choice of ARMA (1, 2) as the best forecasting model. After fitting the model, we performed validation with a new set of data from 30 days of operation, achieving a model of 2.7% mean absolute percent error.
基金support provided by the National Natural Science Foundation of China(51908083,52270058)the Venture&Innovation Support Program for Chongqing Overseas Returnees(CX2021121)+1 种基金the National Key Research and Development Program of China(2022YFC3203402)the Graduate Research and Innovation Foundation of Chongqing,China(CYS22066)。
文摘Ammonia recovery from wastewater is crucial,yet technology of low carbon emission and high ammonia perm-selectivity against complex stream compositions is urgently needed.Herein,a membrane-based hybrid process of the Donnan dialysiseelectrodialysis process(DDeED)was proposed for sustainable and efficient ammonia recovery.In principle,DD removes the majority of ammonia in wastewater by exploring the concentration gradient of NH4 t and driven cation(Nat)across the cation exchange membrane,given industrial sodium salt as a driving chemical.An additional ED stage driven by solar energy realizes a further removal of ammonia,recovery of driven cation,and replenishment of OHtoward ammonia stripping.Our results demonstrated that the hybrid DDeED process achieved ammonia removal efficiency>95%,driving cation(Nat)recovery efficiency>87.1%for synthetic streams,and reduced the OH-loss by up to 78%compared to a standalone DD case.Ammonia fluxes of 98.2 gN m^(-2)d^(-1)with the real anaerobic digestion effluent were observed using only solar energy input at 3.8 kWh kgN^(-1).With verified mass transfer modeling,reasonably controlled operation,and beneficial recovery performance,the hybrid process can be a promising candidate for future nutrient recovery from wastewater in a rural,remote area.
