2024 Vol. 42, No. 8
Display Method:
2024, 42(8): 1-7.
doi: 10.13205/j.hjgc.202408001
Abstract:
To address the challenge of managing substantial quantities of dredged sediments during the construction of hydropower stations, we collected hydrostatic sediment samples from the overburden riverbed at the dam site of Lawa Hydropower Station in the upstream region of Jinsha River. The sediment samples underwent analysis to determine their physicochemical properties and heavy metals concentrations. The contamination levels of heavy metals in the sediment and their associated ecological risk were assessed, followed by a discussion on the feasible resource utilization of the sediments. The findings revealed that the pH values of the sediment samples ranged from 7.77 to 7.91, indicating weak alkalinity. The coefficient uniformity (Cμ) exceeded 10, suggesting diverse particle fractions and continuous grading within the sediment. The sediment texture was classified as loam, including sandy loam and silty sandy loam. The organic matter content in sediment samples ranged from 1.33% to 1.86%, which was at a low level, indicating limited nutrient availability. The geoaccumulation index (Igeo) indicated that the sediment samples were not contaminated by heavy metals. According to the potential ecological risk index, only Cd in the sediment sample collected from prospecting line Ⅰ posed a moderate potential ecological risk. The dammed lake hydrostatic sediments can serve as the substituted topsoil capping material for landscaping, or building materials. To enhance the fertility of the sediment capping layer due to its inherent lack of organic matter, it’s suggested to be incorporated with local-sourced municipal sewage sludge, kitchen waste, livestock, and poultry manures along with their composts, which are rich in both organic matter and nutrients. The compressive and flexural strengths of sediment-based building materials can be improved through incorporating coal cinder, cement, or other solidification technologies.
To address the challenge of managing substantial quantities of dredged sediments during the construction of hydropower stations, we collected hydrostatic sediment samples from the overburden riverbed at the dam site of Lawa Hydropower Station in the upstream region of Jinsha River. The sediment samples underwent analysis to determine their physicochemical properties and heavy metals concentrations. The contamination levels of heavy metals in the sediment and their associated ecological risk were assessed, followed by a discussion on the feasible resource utilization of the sediments. The findings revealed that the pH values of the sediment samples ranged from 7.77 to 7.91, indicating weak alkalinity. The coefficient uniformity (Cμ) exceeded 10, suggesting diverse particle fractions and continuous grading within the sediment. The sediment texture was classified as loam, including sandy loam and silty sandy loam. The organic matter content in sediment samples ranged from 1.33% to 1.86%, which was at a low level, indicating limited nutrient availability. The geoaccumulation index (Igeo) indicated that the sediment samples were not contaminated by heavy metals. According to the potential ecological risk index, only Cd in the sediment sample collected from prospecting line Ⅰ posed a moderate potential ecological risk. The dammed lake hydrostatic sediments can serve as the substituted topsoil capping material for landscaping, or building materials. To enhance the fertility of the sediment capping layer due to its inherent lack of organic matter, it’s suggested to be incorporated with local-sourced municipal sewage sludge, kitchen waste, livestock, and poultry manures along with their composts, which are rich in both organic matter and nutrients. The compressive and flexural strengths of sediment-based building materials can be improved through incorporating coal cinder, cement, or other solidification technologies.
2024, 42(8): 8-16.
doi: 10.13205/j.hjgc.202408002
Abstract:
To maintain the stability of the Suaeda salsa population and their patterns, the Yellow River Delta National Nature Reserve has carried out ecological restoration projects in the degraded Suaeda salsa wetlands since 2019. Two types of restoration measures were carried out in the degraded area: microtopographic adjustment, and replenishing fresh water to reduce soil salinity. In order to evaluate the effect of the two restoration measures, we monitored and analyzed the morphological and population characteristics of Suaeda salsa, soil physicochemical properties, and macrobenthos community characteristics in the restoration project, degraded wetlands, and natural wetlands. The results showed that microtopographic adjustment was the most effective measure, while the density, coverage, and biomass of Suaeda salsa in the restoration project were higher than those in the degraded wetland, and were close to the natural wetland. In addition, the density of macrobenthos was increased, but the community structure of macrobenthos had been changed, and the diversity and evenness index decreased. On the contrary, the effect of the replenishment of fresh water was not significant, which might be caused by the interruption of fresh water.
To maintain the stability of the Suaeda salsa population and their patterns, the Yellow River Delta National Nature Reserve has carried out ecological restoration projects in the degraded Suaeda salsa wetlands since 2019. Two types of restoration measures were carried out in the degraded area: microtopographic adjustment, and replenishing fresh water to reduce soil salinity. In order to evaluate the effect of the two restoration measures, we monitored and analyzed the morphological and population characteristics of Suaeda salsa, soil physicochemical properties, and macrobenthos community characteristics in the restoration project, degraded wetlands, and natural wetlands. The results showed that microtopographic adjustment was the most effective measure, while the density, coverage, and biomass of Suaeda salsa in the restoration project were higher than those in the degraded wetland, and were close to the natural wetland. In addition, the density of macrobenthos was increased, but the community structure of macrobenthos had been changed, and the diversity and evenness index decreased. On the contrary, the effect of the replenishment of fresh water was not significant, which might be caused by the interruption of fresh water.
2024, 42(8): 17-24.
doi: 10.13205/j.hjgc.202408003
Abstract:
Regional water quality monitoring and cause analysis are important prerequisites for controlling water pollution. Based on the surface water quality data of 547 monitoring sections in Hunan Province from 2021 to 2022, and the GB 3838—2002 Surface Water Environmental Quality Standard, the temporal variation patterns and regional differences in surface water quality in Hunan Province were analyzed. The principal component analysis method was used to identify the main pollution indicators, and the grey relational analysis method was applied to explore the main factors driving the heterogeneity of water quality. The results showed that from 2021 to 2022, the overall surface water quality in Hunan Province was good, with the proportion of Class I to II sections not less than 70% each month. The monthly variation characteristics of surface water quality in Hunan Province showed that the quality in summer was inferior to other seasons. Compared with 2021, the water quality improved in 2022. The main pollution indicators in Hunan Province are the permanganate index, ammonia nitrogen, total phosphorus, and dissolved oxygen. Among the various driving factors, the total industrial water intake, urban sewage discharge, gross regional product, and urban population had an average grey relational grade greater than 0.8 with water quality indicators, which are key factors driving the heterogeneity of surface water quality in different cities and closely related to the water environmental quality of industrial cities.
Regional water quality monitoring and cause analysis are important prerequisites for controlling water pollution. Based on the surface water quality data of 547 monitoring sections in Hunan Province from 2021 to 2022, and the GB 3838—2002 Surface Water Environmental Quality Standard, the temporal variation patterns and regional differences in surface water quality in Hunan Province were analyzed. The principal component analysis method was used to identify the main pollution indicators, and the grey relational analysis method was applied to explore the main factors driving the heterogeneity of water quality. The results showed that from 2021 to 2022, the overall surface water quality in Hunan Province was good, with the proportion of Class I to II sections not less than 70% each month. The monthly variation characteristics of surface water quality in Hunan Province showed that the quality in summer was inferior to other seasons. Compared with 2021, the water quality improved in 2022. The main pollution indicators in Hunan Province are the permanganate index, ammonia nitrogen, total phosphorus, and dissolved oxygen. Among the various driving factors, the total industrial water intake, urban sewage discharge, gross regional product, and urban population had an average grey relational grade greater than 0.8 with water quality indicators, which are key factors driving the heterogeneity of surface water quality in different cities and closely related to the water environmental quality of industrial cities.
2024, 42(8): 25-34.
doi: 10.13205/j.hjgc.202408004
Abstract:
In this paper, microporous-rich biomass charcoal (referred to as FWB) was prepared using waste fir wood chips as the raw material, and 2,4-dichlorophenol (2,4-DCP) was used as the target pollutant. The effects of different adsorption conditions on the adsorption performance of 2,4-DCP by FWB were studied, and the kinetic models (quasi-primary kinetics, quasi-secondary kinetics and intraparticle diffusion models), isothermal adsorption models (Langmuir, Freundlich and Temkin models) and the adsorption thermodynamic model (Van’t Hoff model) were used to fit the adsorption process and analyze its adsorption characteristics. The basic characteristics and adsorption mechanism of FWB were analyzed by SEM-EDS, BET, FTIR, XRD and XPS. The results showed that the adsorption process followed the quasi-secondary kinetic model and the Freundlich model, i.e. the adsorption of 2,4-DCP by FWB was based on the chemisorption of multilayers, with a maximum adsorption capacity of 138.05 mg/g. The adsorption process was a spontaneous heat absorption process. The biochar possesses a high specific surface area (326.770 m2/g), and an average pore size of 1.960. The total pore volume is 0.219 mL/g, and the micro-pore volume (0.178 mL/g) accounts for 81.279% of the total pore volume.
In this paper, microporous-rich biomass charcoal (referred to as FWB) was prepared using waste fir wood chips as the raw material, and 2,4-dichlorophenol (2,4-DCP) was used as the target pollutant. The effects of different adsorption conditions on the adsorption performance of 2,4-DCP by FWB were studied, and the kinetic models (quasi-primary kinetics, quasi-secondary kinetics and intraparticle diffusion models), isothermal adsorption models (Langmuir, Freundlich and Temkin models) and the adsorption thermodynamic model (Van’t Hoff model) were used to fit the adsorption process and analyze its adsorption characteristics. The basic characteristics and adsorption mechanism of FWB were analyzed by SEM-EDS, BET, FTIR, XRD and XPS. The results showed that the adsorption process followed the quasi-secondary kinetic model and the Freundlich model, i.e. the adsorption of 2,4-DCP by FWB was based on the chemisorption of multilayers, with a maximum adsorption capacity of 138.05 mg/g. The adsorption process was a spontaneous heat absorption process. The biochar possesses a high specific surface area (326.770 m2/g), and an average pore size of 1.960. The total pore volume is 0.219 mL/g, and the micro-pore volume (0.178 mL/g) accounts for 81.279% of the total pore volume.
2024, 42(8): 35-42.
doi: 10.13205/j.hjgc.202408005
Abstract:
The conventional biological nitrogen removal of wastewater with low C/N ratio and high ammonia nitrogen has some deficiencies, such as high energy consumption of aeration, and high amount of added carbon source. In this study, a shortcut nitrogen removal system for algal-bacterial symbiosis was constructed by combining shortcut nitrification functional sludge enriched with ammonia-oxidizing bacteria (AOB) with Chlorella. The effects of the film coating method and light intensity on nitrogen and phosphorus removal in the system were studied. The high-throughput sequencing technology was used to analyze the microbial community structure, and to analyze and determine the nitrogen conversion pathway in the system. The results demonstrated that the relative abundance of AOB in acclimated sludge was 19.31%, of which the main strain was Nitrosomonas, accounting for 94.41% of total AOB. The shortcut nitrification ability of acclimated sludge was excellent. An efficient nitrogen removal was achieved in the algal-bacterial symbiotic system. When first inoculating sludge and then inoculating microalgae, and the light intensity was set to 5000 lux, the best removal efficiency of TN and TP from simulated biogas slurry in the system could be realized as high as 93.22% and 82.38%, respectively. After stable operation of the system for 37 days, the microbial richness of the algal-bacterial symbiotic biofilm increased, and the nitrogen removal efficiency was higher than 90%. In biofilm, Thauera, with an relative abundance of 56.42%, played a dominant role in denitrification, while the relative abundance of AOB was reduced to 5.65%, and the abundance of NOB was very low. The high efficiency of nitrogen removal was realized through the shortcut nitrification-denitrification process (about 88.46%) and biological assimilation (about 6.79%) in shortcut nitrogen removal system for algal-bacterial symbiosis. About 60.5% of the carbon source for denitrification was saved, compared with traditional biological denitrification technology.
The conventional biological nitrogen removal of wastewater with low C/N ratio and high ammonia nitrogen has some deficiencies, such as high energy consumption of aeration, and high amount of added carbon source. In this study, a shortcut nitrogen removal system for algal-bacterial symbiosis was constructed by combining shortcut nitrification functional sludge enriched with ammonia-oxidizing bacteria (AOB) with Chlorella. The effects of the film coating method and light intensity on nitrogen and phosphorus removal in the system were studied. The high-throughput sequencing technology was used to analyze the microbial community structure, and to analyze and determine the nitrogen conversion pathway in the system. The results demonstrated that the relative abundance of AOB in acclimated sludge was 19.31%, of which the main strain was Nitrosomonas, accounting for 94.41% of total AOB. The shortcut nitrification ability of acclimated sludge was excellent. An efficient nitrogen removal was achieved in the algal-bacterial symbiotic system. When first inoculating sludge and then inoculating microalgae, and the light intensity was set to 5000 lux, the best removal efficiency of TN and TP from simulated biogas slurry in the system could be realized as high as 93.22% and 82.38%, respectively. After stable operation of the system for 37 days, the microbial richness of the algal-bacterial symbiotic biofilm increased, and the nitrogen removal efficiency was higher than 90%. In biofilm, Thauera, with an relative abundance of 56.42%, played a dominant role in denitrification, while the relative abundance of AOB was reduced to 5.65%, and the abundance of NOB was very low. The high efficiency of nitrogen removal was realized through the shortcut nitrification-denitrification process (about 88.46%) and biological assimilation (about 6.79%) in shortcut nitrogen removal system for algal-bacterial symbiosis. About 60.5% of the carbon source for denitrification was saved, compared with traditional biological denitrification technology.
2024, 42(8): 43-50.
doi: 10.13205/j.hjgc.202408006
Abstract:
To explore the effect of dynamic mixing on strengthening coagulation and its influencing factors, a comparative test of the coagulation effect was carried out with the assistance of dynamic mixing, static mixing, and tube mixing pilot test equipment in a water supply plant. The results showed that the comprehensive flocculation effect was ranked as dynamic mixing>static mixing>tube mixing. The removal rates of turbidity and chroma of dynamic mixing could reach 91% and 95%, respectively. The floc form was large and dense, which was conducive to sedimentation. The floc of static mixing and tube mixing was relatively loose. The removal rate of CODMn and TOC by dynamic mixing and other mixing methods was only in a range of 20% to 35%. Dynamic mixing had a better treatment effect on low temperature and turbidity water at a lower PAC dosage (20 mg/L), and the turbidity removal rate can still reach 90%. The study on the influence of flow rate, speed, turbine angle, pipe-turbine diameter ratio, installation distance, and other factors on dynamic mixing showed that the application of the dynamic mixing method should be combined with a low speed and a short installation distance from the flocculation tank in the treatment of small flow rate, while the opposite is true for a large flow rate. It is recommended to choose a smaller turbine angle (30° to 45°), and the turbine diameter ratio has no significant influence on the coagulation effect.
To explore the effect of dynamic mixing on strengthening coagulation and its influencing factors, a comparative test of the coagulation effect was carried out with the assistance of dynamic mixing, static mixing, and tube mixing pilot test equipment in a water supply plant. The results showed that the comprehensive flocculation effect was ranked as dynamic mixing>static mixing>tube mixing. The removal rates of turbidity and chroma of dynamic mixing could reach 91% and 95%, respectively. The floc form was large and dense, which was conducive to sedimentation. The floc of static mixing and tube mixing was relatively loose. The removal rate of CODMn and TOC by dynamic mixing and other mixing methods was only in a range of 20% to 35%. Dynamic mixing had a better treatment effect on low temperature and turbidity water at a lower PAC dosage (20 mg/L), and the turbidity removal rate can still reach 90%. The study on the influence of flow rate, speed, turbine angle, pipe-turbine diameter ratio, installation distance, and other factors on dynamic mixing showed that the application of the dynamic mixing method should be combined with a low speed and a short installation distance from the flocculation tank in the treatment of small flow rate, while the opposite is true for a large flow rate. It is recommended to choose a smaller turbine angle (30° to 45°), and the turbine diameter ratio has no significant influence on the coagulation effect.
2024, 42(8): 51-60.
doi: 10.13205/j.hjgc.202408007
Abstract:
The interception facility is a key structure in water pollution control. To investigate the fluid movement and the determination method of interception capacity in different interceptor facilities, pilot test, and computational fluid dynamics simulation were conducted. The results of fluid motion analysis showed that the narrowing effect of the overflow section made different water flow characteristics in the interceptor, which can be divided into wide top weir flow stage, gate hole free flow stage, gate hole flooded flow stage, and full tube with pressure flow stage. The water blocking and flow turning of the weir make the weir-type interceptor prone to siltation at the side away from the interceptor. The slot interceptor was influenced by the falling water of the slot, and the water flow fragmentation and a large amount of gas doping occurred, increasing the water loss; the slot and weir interceptor were mainly influenced by the slot, when the ratio of the weir to the slot was less than 1.2, and the influence of the weir dominated when the ratio was greater than 1.4. In this study, combined with hydrodynamics and mathematical analysis, the determination methods of interception capacity of different types of interceptors are derived.
The interception facility is a key structure in water pollution control. To investigate the fluid movement and the determination method of interception capacity in different interceptor facilities, pilot test, and computational fluid dynamics simulation were conducted. The results of fluid motion analysis showed that the narrowing effect of the overflow section made different water flow characteristics in the interceptor, which can be divided into wide top weir flow stage, gate hole free flow stage, gate hole flooded flow stage, and full tube with pressure flow stage. The water blocking and flow turning of the weir make the weir-type interceptor prone to siltation at the side away from the interceptor. The slot interceptor was influenced by the falling water of the slot, and the water flow fragmentation and a large amount of gas doping occurred, increasing the water loss; the slot and weir interceptor were mainly influenced by the slot, when the ratio of the weir to the slot was less than 1.2, and the influence of the weir dominated when the ratio was greater than 1.4. In this study, combined with hydrodynamics and mathematical analysis, the determination methods of interception capacity of different types of interceptors are derived.
2024, 42(8): 61-71.
doi: 10.13205/j.hjgc.202408008
Abstract:
Particulate matter is the primary carrier of nitrogen and phosphorus in stormwater runoff, and controlling the particulate matter with large nitrogen and phosphorus content can effectively reduce the total pollution load. Particulate-borne nitrogen and phosphorus are susceptible to transformation influenced by external environmental factors such as pH, temperature, dissolved oxygen, organic matter, and so on. This paper firstly summarizes the sources of nitrogen and phosphorus contained in runoff particulate matter, and comparatively analyzes the characteristics of nitrogen and phosphorus components in surface, pipeline, and water sediment. It was found that in the three types of sediments, total nitrogen was composed of 88% to 92% organic nitrogen and 8% to 12% inorganic nitrogen, while total phosphorus was composed of 5% to 20% organic phosphorus and 80% to 95% inorganic phosphorus. Furthermore, it summarizes the particle size distribution of particulate matter in different scenarios, along with the variations in the main ranges of nitrogen and phosphorus pollutants on particles of different sizes. Sediments within the particle size range of 11 to 150 μm contribute 20% to 50% of particulate nitrogen and 40% to 50% of particulate phosphorus in stormwater runoff. An analysis was also conducted on the inherent characteristics of particulate matter (particle size, metal composition, surface morphology), other environmental factors (pH, temperature, dissolved oxygen, organic matter), and the impact of microorganisms on the forms of nitrogen and phosphorus carried by the particulate matter. For example, when water temperature increased from 6.85 ℃ to 29.85 ℃, the adsorption rate of phosphorus by particulate matter increased by 12%. This article summarizes the shortcomings in the relevant studies on nitrogen and phosphorus pollutants in particulate matter, aiming to provide insights for precise control of nitrogen and phosphorus pollution in urban runoff.
Particulate matter is the primary carrier of nitrogen and phosphorus in stormwater runoff, and controlling the particulate matter with large nitrogen and phosphorus content can effectively reduce the total pollution load. Particulate-borne nitrogen and phosphorus are susceptible to transformation influenced by external environmental factors such as pH, temperature, dissolved oxygen, organic matter, and so on. This paper firstly summarizes the sources of nitrogen and phosphorus contained in runoff particulate matter, and comparatively analyzes the characteristics of nitrogen and phosphorus components in surface, pipeline, and water sediment. It was found that in the three types of sediments, total nitrogen was composed of 88% to 92% organic nitrogen and 8% to 12% inorganic nitrogen, while total phosphorus was composed of 5% to 20% organic phosphorus and 80% to 95% inorganic phosphorus. Furthermore, it summarizes the particle size distribution of particulate matter in different scenarios, along with the variations in the main ranges of nitrogen and phosphorus pollutants on particles of different sizes. Sediments within the particle size range of 11 to 150 μm contribute 20% to 50% of particulate nitrogen and 40% to 50% of particulate phosphorus in stormwater runoff. An analysis was also conducted on the inherent characteristics of particulate matter (particle size, metal composition, surface morphology), other environmental factors (pH, temperature, dissolved oxygen, organic matter), and the impact of microorganisms on the forms of nitrogen and phosphorus carried by the particulate matter. For example, when water temperature increased from 6.85 ℃ to 29.85 ℃, the adsorption rate of phosphorus by particulate matter increased by 12%. This article summarizes the shortcomings in the relevant studies on nitrogen and phosphorus pollutants in particulate matter, aiming to provide insights for precise control of nitrogen and phosphorus pollution in urban runoff.
2024, 42(8): 72-77.
doi: 10.13205/j.hjgc.202408009
Abstract:
Sewage contains abundant heat energy. Recycling heat energy in sewage is an important research direction in the field of energy conservation. Sewage source heat pump technology is an important technical means for recycling sewage heat energy. However, the long-term operation of sewage source heat pump in sewage will cause its heat exchanger affected by corrosion and scaling, thereby reducing the conversion efficiency of sewage heat energy and the resource utilization rate of sewage treatment plants. Therefore, taking the water source heat pump heat exchanger of urban sewage treatment plant as the research object, the key water quality factors affecting its heat transfer performance are deeply explored, and the effect of protective measures taken under complex water quality conditions is comprehensively evaluated. This study provides a reference for solving the long-term pollution problems of water source heat pump heat exchanger in the sewage treatment process with high efficiency and low cost, helps achieve the goal of carbon neutralization operation of sewage treatment.
Sewage contains abundant heat energy. Recycling heat energy in sewage is an important research direction in the field of energy conservation. Sewage source heat pump technology is an important technical means for recycling sewage heat energy. However, the long-term operation of sewage source heat pump in sewage will cause its heat exchanger affected by corrosion and scaling, thereby reducing the conversion efficiency of sewage heat energy and the resource utilization rate of sewage treatment plants. Therefore, taking the water source heat pump heat exchanger of urban sewage treatment plant as the research object, the key water quality factors affecting its heat transfer performance are deeply explored, and the effect of protective measures taken under complex water quality conditions is comprehensively evaluated. This study provides a reference for solving the long-term pollution problems of water source heat pump heat exchanger in the sewage treatment process with high efficiency and low cost, helps achieve the goal of carbon neutralization operation of sewage treatment.
2024, 42(8): 78-86.
doi: 10.13205/j.hjgc.202408010
Abstract:
In recent years, water pollution incidents in industrial parks have occurred frequently. As the important province of chemical industry in China, Jiangsu is with the status of the dense water system, industrial agglomeration, and severe and complex environmental security situation. It was urgently needed to research the environmental risk prevention and control system of sudden water pollution incidents for Jiangsu Province. Based on the investigation data of the three-level prevention and control system of sudden water pollution incidents in typical industrial parks, the experiences and existing problems in the three-level prevention and control system construction of sudden water pollution incidents in Jiangsu Province were analyzed in recent years, and the key design points of the three-level prevention and control system were expounded from the aspects of emergency pool construction, environmental emergency interception dam, and the intelligent emergency system. At the same time, this study took a heavy industrial park with prominent environmental risks as an example to carry out the design of a three-level prevention and control system for the enterprises, public pipe networks (emergency pools) and water bodies in the area, in order to provide reference for other regions to carry out water environment risk prevention and control.
In recent years, water pollution incidents in industrial parks have occurred frequently. As the important province of chemical industry in China, Jiangsu is with the status of the dense water system, industrial agglomeration, and severe and complex environmental security situation. It was urgently needed to research the environmental risk prevention and control system of sudden water pollution incidents for Jiangsu Province. Based on the investigation data of the three-level prevention and control system of sudden water pollution incidents in typical industrial parks, the experiences and existing problems in the three-level prevention and control system construction of sudden water pollution incidents in Jiangsu Province were analyzed in recent years, and the key design points of the three-level prevention and control system were expounded from the aspects of emergency pool construction, environmental emergency interception dam, and the intelligent emergency system. At the same time, this study took a heavy industrial park with prominent environmental risks as an example to carry out the design of a three-level prevention and control system for the enterprises, public pipe networks (emergency pools) and water bodies in the area, in order to provide reference for other regions to carry out water environment risk prevention and control.
2024, 42(8): 87-96.
doi: 10.13205/j.hjgc.202408011
Abstract:
Nitrogen oxides, as one of the atmospheric pollutants, have caused serious environmental problems, endangering the ecological environment and human health. Selective catalytic reduction of NOx with ammonia (NH3-SCR) has become an important application technology for denitrification. Different from the supported ZSM-5 catalyst synthesized by traditional methods, Ce and Mn bimetallic modified ZSM-5 catalyst was synthesized by one-pot method, and the ZSM-5 molecular sieve was pretreated by alkali. The CeMn/ZSM-5-OH catalyst with improved surface area and pore structure was successfully synthesized. In the performance test, the NOx conversion rate was beyond 90% in the temperature range of 175 to 350 ℃, and the activity was increased by nearly 40%, compared with that of CeMn/ZSM-5 samples in low temperature section. After alkali-treatment, the CeMn/ZSM-5-OH catalyst generated more Ce3+ and Mn4+, which increased the adsorption performance of NO and NH3. The results of XPS showed that lattice oxygen participated in the electron transfer between Ce3+ and Mn4+, which was conducive to the activation of NO and NH3. Thus, the NH3-SCR reaction was promoted.
Nitrogen oxides, as one of the atmospheric pollutants, have caused serious environmental problems, endangering the ecological environment and human health. Selective catalytic reduction of NOx with ammonia (NH3-SCR) has become an important application technology for denitrification. Different from the supported ZSM-5 catalyst synthesized by traditional methods, Ce and Mn bimetallic modified ZSM-5 catalyst was synthesized by one-pot method, and the ZSM-5 molecular sieve was pretreated by alkali. The CeMn/ZSM-5-OH catalyst with improved surface area and pore structure was successfully synthesized. In the performance test, the NOx conversion rate was beyond 90% in the temperature range of 175 to 350 ℃, and the activity was increased by nearly 40%, compared with that of CeMn/ZSM-5 samples in low temperature section. After alkali-treatment, the CeMn/ZSM-5-OH catalyst generated more Ce3+ and Mn4+, which increased the adsorption performance of NO and NH3. The results of XPS showed that lattice oxygen participated in the electron transfer between Ce3+ and Mn4+, which was conducive to the activation of NO and NH3. Thus, the NH3-SCR reaction was promoted.
2024, 42(8): 97-104.
doi: 10.13205/j.hjgc.202408012
Abstract:
Chlorinated volatile organic compounds (Cl-VOCs) such as chlorobenzenes, are difficult to remove from the environment because they are hydrophobic, volatile, and biotoxic. In this study, an electrochemical oxidation system was constructed to investigate the effect of a single factor, current density, electrode distance, and electrolyte concentration on the removal of chlorobenzene gas, using response surface methodology (RSM), and a prediction model by Design-Expert 10.0.1 software was established to optimize the reaction condition. The results of one-factor experiments showed that when treating 2.90 g/m3 chlorobenzene gas with 0.40 L/min flow rate, Ti/Ti4O7 as anode, stainless steel wire mesh as cathode, 0.15 mol/L NaCl electrolyte, 10.0 mA/cm2 current density and 4.0 cm electrode distance, and then the average removal efficiency (RE), efficiency capacity (EC) and energy consumption (Esp) was 57.99%, 20.18 g/(m3·h) and 190.2 kW·h/kg, respectively. The results of RSM showed that current density had significant effect on RE, while the electrolyte concentration had the least effect; electrolyte concentration and current density had the biggest interaction effect on RE; the optimal experimental conditions were as follows: 0.149 mol/L NaCl, 18.11 mA/cm2 current density, 3.804 cm electrode distance, and under these conditions, the RE achieved 66.43%; it also showed that the regression model reached significant level, and the validation results was in agreement with the predicted results, which proved the feasibility of the model in treating actual waste gas.
Chlorinated volatile organic compounds (Cl-VOCs) such as chlorobenzenes, are difficult to remove from the environment because they are hydrophobic, volatile, and biotoxic. In this study, an electrochemical oxidation system was constructed to investigate the effect of a single factor, current density, electrode distance, and electrolyte concentration on the removal of chlorobenzene gas, using response surface methodology (RSM), and a prediction model by Design-Expert 10.0.1 software was established to optimize the reaction condition. The results of one-factor experiments showed that when treating 2.90 g/m3 chlorobenzene gas with 0.40 L/min flow rate, Ti/Ti4O7 as anode, stainless steel wire mesh as cathode, 0.15 mol/L NaCl electrolyte, 10.0 mA/cm2 current density and 4.0 cm electrode distance, and then the average removal efficiency (RE), efficiency capacity (EC) and energy consumption (Esp) was 57.99%, 20.18 g/(m3·h) and 190.2 kW·h/kg, respectively. The results of RSM showed that current density had significant effect on RE, while the electrolyte concentration had the least effect; electrolyte concentration and current density had the biggest interaction effect on RE; the optimal experimental conditions were as follows: 0.149 mol/L NaCl, 18.11 mA/cm2 current density, 3.804 cm electrode distance, and under these conditions, the RE achieved 66.43%; it also showed that the regression model reached significant level, and the validation results was in agreement with the predicted results, which proved the feasibility of the model in treating actual waste gas.
2024, 42(8): 105-115.
doi: 10.13205/j.hjgc.202408013
Abstract:
Atmospheric particulate matter concentration is closely related to environmental pollution, and accurate prediction of PM2.5 concentration is crucial for ecological environmental protection. Based on PM2.5 concentration and meteorological data from January 1, 2020, to December 31, 2021, in Xi’an, the PM2.5 concentration series was decomposed into multiple eigenmodal components by complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) for the non-stationary and non-linear characteristics, and the sample entropy (SE) was used as an indicator to perform k-means clustering to reduce data noise. Then the reconstructed components were inputted into a bi-directional long short-term memory model (BiLSTM model), supplemented with the enhanced information of meteorological data and temporal data after unique thermal coding processing to output the prediction results of each component, finally superimposed to obtain the final PM2.5 concentration prediction results. The results showed that the CEEMDAN-SE-BiLSTM model had better prediction performance at four future moments (T+3, T+6, T+12, and T+24) compared with the XGBoost model, long short-term memory neural network (LSTM) model, BiLSTM model, and other combined models. The CEEMDAN-SE-BiLSTM model had better prediction performance, in terms of root mean square error (RMSE), mean absolute error (MAE), and mean absolute percentage error (MAPE) were all decreased and at the moment of T+3, the determination coefficient (R2) was 0.993. The prediction accuracy was greatly improved. In addition, five cities (Zhengzhou, Chengdu, Beijing, Shanghai, and Guangzhou) were randomly selected nationwide to verify the model’s generalization, and the results showed that the prediction errors in the five cities were all small. The CEEMDAN-SE-BiLSTM model can be extended to other regions and cities and is capable of accurate short-term prediction.
Atmospheric particulate matter concentration is closely related to environmental pollution, and accurate prediction of PM2.5 concentration is crucial for ecological environmental protection. Based on PM2.5 concentration and meteorological data from January 1, 2020, to December 31, 2021, in Xi’an, the PM2.5 concentration series was decomposed into multiple eigenmodal components by complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) for the non-stationary and non-linear characteristics, and the sample entropy (SE) was used as an indicator to perform k-means clustering to reduce data noise. Then the reconstructed components were inputted into a bi-directional long short-term memory model (BiLSTM model), supplemented with the enhanced information of meteorological data and temporal data after unique thermal coding processing to output the prediction results of each component, finally superimposed to obtain the final PM2.5 concentration prediction results. The results showed that the CEEMDAN-SE-BiLSTM model had better prediction performance at four future moments (T+3, T+6, T+12, and T+24) compared with the XGBoost model, long short-term memory neural network (LSTM) model, BiLSTM model, and other combined models. The CEEMDAN-SE-BiLSTM model had better prediction performance, in terms of root mean square error (RMSE), mean absolute error (MAE), and mean absolute percentage error (MAPE) were all decreased and at the moment of T+3, the determination coefficient (R2) was 0.993. The prediction accuracy was greatly improved. In addition, five cities (Zhengzhou, Chengdu, Beijing, Shanghai, and Guangzhou) were randomly selected nationwide to verify the model’s generalization, and the results showed that the prediction errors in the five cities were all small. The CEEMDAN-SE-BiLSTM model can be extended to other regions and cities and is capable of accurate short-term prediction.
2024, 42(8): 116-124.
doi: 10.13205/j.hjgc.202408014
Abstract:
To understand the influence of blending antibiotic filter residue on the combustion performance of municipal solid waste, this paper selected a typical streptomycin residue and studied the combustion characteristics and synergies of municipal solid waste mixed streptomycin residue by thermogravimetric analyzer. The kinetic characteristics of the samples were analyzed by the Kissen-Akahire-Sunose (KAS) method and Flynn-Wall-Ozawa (FWO) method, and the NO emission characteristics of the samples were studied by blended combustion experiments on a fixed bed. The results showed that when the mixture ratio was 10%, the flammability index of the sample increased by 9.7%, the comprehensive combustion characteristic index increased by 11.1%, and the average activation energy decreased by 6.9%. The synergistic effect of the mixed combustion process of the two substances is mainly the promotion on the combustion of fixed carbon. With the increase of the mixing ratio from 10% to 30%, the flammability index and comprehensive combustion characteristic index of the sample gradually decreased, the average activation energy gradually increased, and the synergistic effect changed to inhibit the combustion of fixed carbon. The concentration of NO emission increased with the increase of the mixing proportion of streptomycin residue, and the interaction between streptomycin residue and municipal solid waste further promoted the emission of NO.
To understand the influence of blending antibiotic filter residue on the combustion performance of municipal solid waste, this paper selected a typical streptomycin residue and studied the combustion characteristics and synergies of municipal solid waste mixed streptomycin residue by thermogravimetric analyzer. The kinetic characteristics of the samples were analyzed by the Kissen-Akahire-Sunose (KAS) method and Flynn-Wall-Ozawa (FWO) method, and the NO emission characteristics of the samples were studied by blended combustion experiments on a fixed bed. The results showed that when the mixture ratio was 10%, the flammability index of the sample increased by 9.7%, the comprehensive combustion characteristic index increased by 11.1%, and the average activation energy decreased by 6.9%. The synergistic effect of the mixed combustion process of the two substances is mainly the promotion on the combustion of fixed carbon. With the increase of the mixing ratio from 10% to 30%, the flammability index and comprehensive combustion characteristic index of the sample gradually decreased, the average activation energy gradually increased, and the synergistic effect changed to inhibit the combustion of fixed carbon. The concentration of NO emission increased with the increase of the mixing proportion of streptomycin residue, and the interaction between streptomycin residue and municipal solid waste further promoted the emission of NO.
2024, 42(8): 125-133.
doi: 10.13205/j.hjgc.202408015
Abstract:
Food waste (FW) and waste-activated sludge (WAS) were utilized to study the effects of different FW proportions (0%, 25%, 50%, 75%, and 100%) on the performance of anaerobic co-fermentation (Co-AF) for volatile fatty acids (VFAs) synthesis during 16 days. The results demonstrated that injecting FW increased Co-AF performance by promoting organic matter decomposition, balancing the system’s C/N ratio, and delivering critical nutrients. When the FW ratio was 50%, the maximum VFA yield was (282.8±2.9) mg COD/g VSS. The abundance of acidogenic bacteria (Prevotella_7, Lactobacillus, Veillonella) increased steadily during the co-fermentation period, the activities of hydrolytic and acidogenic enzymes were inhibited early but recovered later, and methanogenic enzymes were inhibited throughout the period, which promoted VFA accumulation. This research could promote the utilization of WAS and FW through the Co-AF process.
Food waste (FW) and waste-activated sludge (WAS) were utilized to study the effects of different FW proportions (0%, 25%, 50%, 75%, and 100%) on the performance of anaerobic co-fermentation (Co-AF) for volatile fatty acids (VFAs) synthesis during 16 days. The results demonstrated that injecting FW increased Co-AF performance by promoting organic matter decomposition, balancing the system’s C/N ratio, and delivering critical nutrients. When the FW ratio was 50%, the maximum VFA yield was (282.8±2.9) mg COD/g VSS. The abundance of acidogenic bacteria (Prevotella_7, Lactobacillus, Veillonella) increased steadily during the co-fermentation period, the activities of hydrolytic and acidogenic enzymes were inhibited early but recovered later, and methanogenic enzymes were inhibited throughout the period, which promoted VFA accumulation. This research could promote the utilization of WAS and FW through the Co-AF process.
2024, 42(8): 134-141.
doi: 10.13205/j.hjgc.202408016
Abstract:
To systematically grasp the pollution characteristics and environmental risks of incineration residues, their chemical and mineral composition and pollution characteristics of heavy metals and chlorides were analyzed. The risk assessment code (RAC) and synthesis toxicity index (STI) were used to evaluate the environmental risks of heavy metals. Results showed that grate furnace fly ash presented characteristics of high calcium and chlorine, in which Cu, Zn and Cd were mainly in the F2 state, and leaching toxicity of Pb exceeded the limit, while fluidized bed fly ash was rich in SiO2 and Al2O3, with a Cl content of 5.79%. Hazardous waste and medical waste fly ash presented the same characteristics of high sodium and chlorine, in which Zn, Cd and Ni were mainly in the F1 state, but the difference was that the leaching toxicity of Cu of the former exceeded the limit, while the later was Zn, existing in the form of ZnCl2. Both hazardous waste and medical waste incineration slag were rich in SiO2, Al2O3 and Fe2O3 and with a Cl content of 3.27%, and their Cu and Ni contents reached 7525.5, 991.4 mg/kg and 4168.8, 628.2 mg/kg, respectively. Risk assessment indicated that the STI of grate furnace, fluidized bed, hazardous waste and medical fly ash were also all in moderate or high risk levels, and RAC and STI of all kinds heavy metals in hazardous waste and medical waste incineration slag were in low or moderate risk level. Cu or Pb in incineration residues had a negative impact on human health, and Cd and Cr were both at high carcinogenic risk levels.
To systematically grasp the pollution characteristics and environmental risks of incineration residues, their chemical and mineral composition and pollution characteristics of heavy metals and chlorides were analyzed. The risk assessment code (RAC) and synthesis toxicity index (STI) were used to evaluate the environmental risks of heavy metals. Results showed that grate furnace fly ash presented characteristics of high calcium and chlorine, in which Cu, Zn and Cd were mainly in the F2 state, and leaching toxicity of Pb exceeded the limit, while fluidized bed fly ash was rich in SiO2 and Al2O3, with a Cl content of 5.79%. Hazardous waste and medical waste fly ash presented the same characteristics of high sodium and chlorine, in which Zn, Cd and Ni were mainly in the F1 state, but the difference was that the leaching toxicity of Cu of the former exceeded the limit, while the later was Zn, existing in the form of ZnCl2. Both hazardous waste and medical waste incineration slag were rich in SiO2, Al2O3 and Fe2O3 and with a Cl content of 3.27%, and their Cu and Ni contents reached 7525.5, 991.4 mg/kg and 4168.8, 628.2 mg/kg, respectively. Risk assessment indicated that the STI of grate furnace, fluidized bed, hazardous waste and medical fly ash were also all in moderate or high risk levels, and RAC and STI of all kinds heavy metals in hazardous waste and medical waste incineration slag were in low or moderate risk level. Cu or Pb in incineration residues had a negative impact on human health, and Cd and Cr were both at high carcinogenic risk levels.
2024, 42(8): 142-149.
doi: 10.13205/j.hjgc.202408017
Abstract:
Hydrogen, as an ideal clean energy source, possesses remarkable characteristics such as excellent energy production efficiency, environmental friendliness, and sustainability. However, the insufficient production of hydrogen constrains its primary development in industrial application, thus necessitating the development of economically efficient hydrogen production technology. Utilizing the discarded activated sludge for anaerobic fermentation-based hydrogen production, is with a simpler operation and lower energy consumption, and it can also utilize a wide range of organic waste materials as substrates, demonstrating significant developmental potential. Within the anaerobic fermentation process of sludge for hydrogen production, process models exhibit capabilities including data analysis and prediction, parameter and operational strategy optimization, system and design optimization, as well as multi-factor analysis and system modeling. Through the construction of process models, a better understanding and guidance of the sludge hydrogen production process can be achieved, enabling efficient, stable, and sustainable anaerobic fermentation-based hydrogen production technology. However, different anaerobic fermentation process models have their own advantages and limitations, so it is necessary to summarize the progress of process model research, so as to select the appropriate model for fermentation process optimization and prediction according to the actual situation, and obtain more accurate simulation results and expand the scope of application. Based on this, this paper comprehensively analyzed the latest process progress of hydrogen production by anaerobic fermentation of waste activated sludge, as well as the application status and limitations of anaerobic fermentation process modeling in prediction and optimization. This is helpful to promote the application of sludge anaerobic fermentation for hydrogen production, and realize the sustainable utilization of sludge resources more effectively.
Hydrogen, as an ideal clean energy source, possesses remarkable characteristics such as excellent energy production efficiency, environmental friendliness, and sustainability. However, the insufficient production of hydrogen constrains its primary development in industrial application, thus necessitating the development of economically efficient hydrogen production technology. Utilizing the discarded activated sludge for anaerobic fermentation-based hydrogen production, is with a simpler operation and lower energy consumption, and it can also utilize a wide range of organic waste materials as substrates, demonstrating significant developmental potential. Within the anaerobic fermentation process of sludge for hydrogen production, process models exhibit capabilities including data analysis and prediction, parameter and operational strategy optimization, system and design optimization, as well as multi-factor analysis and system modeling. Through the construction of process models, a better understanding and guidance of the sludge hydrogen production process can be achieved, enabling efficient, stable, and sustainable anaerobic fermentation-based hydrogen production technology. However, different anaerobic fermentation process models have their own advantages and limitations, so it is necessary to summarize the progress of process model research, so as to select the appropriate model for fermentation process optimization and prediction according to the actual situation, and obtain more accurate simulation results and expand the scope of application. Based on this, this paper comprehensively analyzed the latest process progress of hydrogen production by anaerobic fermentation of waste activated sludge, as well as the application status and limitations of anaerobic fermentation process modeling in prediction and optimization. This is helpful to promote the application of sludge anaerobic fermentation for hydrogen production, and realize the sustainable utilization of sludge resources more effectively.
2024, 42(8): 150-158.
doi: 10.13205/j.hjgc.202408018
Abstract:
The pollution and migration characteristics of cadmium (Cd) in typical e-waste disposal areas are still unclear. Thus, the electronic waste dismantling area in Taizhou, Zhejiang, was selected as the research area. The vertical pollution and migration characteristics of Cd in soil were studied through pollution investigation, isothermal adsorption experiment, soil column experiment, and HYDRUS-1D software. The migration model of Cd dissolved from accumulated slag under rainfall leaching was established, and its migration in the soil of the study area was predicted. The results showed that Cd pollution in the soil mainly exists in the southwest of the study area, where there has been a history of leachation of e-waste deposits for nearly 30 years, and soil Cd pollution mainly exists in the depth of 0 to 40 cm. The isothermal adsorption of Cd in the vadose zone soil conformed to the Langmuir equation, with KL and qm of 0.0373 L/kg and 5465 mg/kg, respectively. The two-site model (TSM model) could well simulate the penetration process of Cd in the soil column (R2=0.998). The migration simulation of the accumulated slag in the actual electronic waste dismantling area using the TSM model showed that the measured and simulated values of Cd concentration in the soil of the study area were consistent (R2=0.970), which further verified the reliability of the model. A further 100-year migration simulation was carried out for the Cd dissolved from the accumulated slag. The results indicated that when the Cd concentration eluted from the accumulated slag was 0.02 mg/L, the Cd concentration in the leaching solution at the bottom of the vadose zone in the 100th year was 0.0042 mg/L, which did not exceed Class Ⅲ water quality standard specified in Groundwater Quality Standard (GB/T 14848—2017), indicating that there was no risk of Cd pollution in groundwater under this scenario, and Cd pollution mainly existed in the vadose zone soil. In conclusion, for the slag leaching scenario in the informal dismantling area in Taizhou, Zhejiang, it was necessary to focus on the risk of Cd contamination in the vadose zone soil. It is recommended to clean up and disassemble the slag in time to avoid receiving rain leaching for a long time. However, for areas where the accumulation time of the slag body is less than 30 years, the surface soil (with a depth of 0~40 cm) should be prioritized in remediation.
The pollution and migration characteristics of cadmium (Cd) in typical e-waste disposal areas are still unclear. Thus, the electronic waste dismantling area in Taizhou, Zhejiang, was selected as the research area. The vertical pollution and migration characteristics of Cd in soil were studied through pollution investigation, isothermal adsorption experiment, soil column experiment, and HYDRUS-1D software. The migration model of Cd dissolved from accumulated slag under rainfall leaching was established, and its migration in the soil of the study area was predicted. The results showed that Cd pollution in the soil mainly exists in the southwest of the study area, where there has been a history of leachation of e-waste deposits for nearly 30 years, and soil Cd pollution mainly exists in the depth of 0 to 40 cm. The isothermal adsorption of Cd in the vadose zone soil conformed to the Langmuir equation, with KL and qm of 0.0373 L/kg and 5465 mg/kg, respectively. The two-site model (TSM model) could well simulate the penetration process of Cd in the soil column (R2=0.998). The migration simulation of the accumulated slag in the actual electronic waste dismantling area using the TSM model showed that the measured and simulated values of Cd concentration in the soil of the study area were consistent (R2=0.970), which further verified the reliability of the model. A further 100-year migration simulation was carried out for the Cd dissolved from the accumulated slag. The results indicated that when the Cd concentration eluted from the accumulated slag was 0.02 mg/L, the Cd concentration in the leaching solution at the bottom of the vadose zone in the 100th year was 0.0042 mg/L, which did not exceed Class Ⅲ water quality standard specified in Groundwater Quality Standard (GB/T 14848—2017), indicating that there was no risk of Cd pollution in groundwater under this scenario, and Cd pollution mainly existed in the vadose zone soil. In conclusion, for the slag leaching scenario in the informal dismantling area in Taizhou, Zhejiang, it was necessary to focus on the risk of Cd contamination in the vadose zone soil. It is recommended to clean up and disassemble the slag in time to avoid receiving rain leaching for a long time. However, for areas where the accumulation time of the slag body is less than 30 years, the surface soil (with a depth of 0~40 cm) should be prioritized in remediation.
2024, 42(8): 159-166.
doi: 10.13205/j.hjgc.202408019
Abstract:
The risk screening and intervention values for soil contamination of development land can be used for decision-making on soil pollution risk control and remediation. This study was based on the basic theory and methodology of soil pollution health risk assessment for global development land. It involved selecting multi-medium exposure assessment models, determining localized model parameters, calculating model theoretical values, and correcting model theoretical values. Based on the characteristics of land use for development land and the types of pollutants in typical industries in Shenzhen, the soil risk screening and intervention values for 68 pollutants under the first and second types of land use were established. The classification differences of development land in major countries and regions were analyzed. The study showed that the second-category land screening value of pollutants was higher than the first-category land, and the intervention value of the same pollutant was higher than the screening value. The screening and intervention values were within the representative range of similar soil pollution risk control standards at home and overseas. The main reasons for the differences in screening values at home and overseas are the selection of exposure assessment models, receptor exposure values, soil properties, air characteristics, pollutant toxicity parameters, and the correction of theoretical calculation values for the model. The results will play a guiding role in risk screening and control for soil contamination of development land in Shenzhen.
The risk screening and intervention values for soil contamination of development land can be used for decision-making on soil pollution risk control and remediation. This study was based on the basic theory and methodology of soil pollution health risk assessment for global development land. It involved selecting multi-medium exposure assessment models, determining localized model parameters, calculating model theoretical values, and correcting model theoretical values. Based on the characteristics of land use for development land and the types of pollutants in typical industries in Shenzhen, the soil risk screening and intervention values for 68 pollutants under the first and second types of land use were established. The classification differences of development land in major countries and regions were analyzed. The study showed that the second-category land screening value of pollutants was higher than the first-category land, and the intervention value of the same pollutant was higher than the screening value. The screening and intervention values were within the representative range of similar soil pollution risk control standards at home and overseas. The main reasons for the differences in screening values at home and overseas are the selection of exposure assessment models, receptor exposure values, soil properties, air characteristics, pollutant toxicity parameters, and the correction of theoretical calculation values for the model. The results will play a guiding role in risk screening and control for soil contamination of development land in Shenzhen.
2024, 42(8): 167-172.
doi: 10.13205/j.hjgc.202408020
Abstract:
In this paper, through the combination of emergency monitoring of environmental emergencies and object-oriented Petri net theory, the object-oriented Petri net modeling work was applied to the emergency monitoring linkage system after feasibility analysis. Based on the OPMSE simulation platform, three levels of environmental emergencies are modeled for each city in Liaoning Province, each regional center in Liaoning Province, and the overall Liaoning Province. The model of the joint defense system sets the threshold range of pollutant monitoring capacity at each level, and if the concentration of pollutants in the corresponding air and water exceeds the threshold, the emergency monitoring is handed over to the next level of the emergency monitoring center for processing, thus constructing the model of the joint defense system for the monitoring of environmental emergencies based on the Petri network. The optimized organization system of linkage and defense scheme provides a technical guarantee for emergency monitoring and a theoretical basis for further improvement of the emergency monitoring linkage and defense system for environmental emergencies in Liaoning Province.
In this paper, through the combination of emergency monitoring of environmental emergencies and object-oriented Petri net theory, the object-oriented Petri net modeling work was applied to the emergency monitoring linkage system after feasibility analysis. Based on the OPMSE simulation platform, three levels of environmental emergencies are modeled for each city in Liaoning Province, each regional center in Liaoning Province, and the overall Liaoning Province. The model of the joint defense system sets the threshold range of pollutant monitoring capacity at each level, and if the concentration of pollutants in the corresponding air and water exceeds the threshold, the emergency monitoring is handed over to the next level of the emergency monitoring center for processing, thus constructing the model of the joint defense system for the monitoring of environmental emergencies based on the Petri network. The optimized organization system of linkage and defense scheme provides a technical guarantee for emergency monitoring and a theoretical basis for further improvement of the emergency monitoring linkage and defense system for environmental emergencies in Liaoning Province.
2024, 42(8): 173-183.
doi: 10.13205/j.hjgc.202408021
Abstract:
To investigate the feasibility of the mixture design methodology applied to the construction of composite inoculum, and the optimization of components to address the current problems of long composting cycles and low wood fiber conversion efficiency of garden waste, the degrading strains from the GW compost samples and their interrelationships were identified, using isolation culture and antagonism experiments. The non-antagonistic strains were mixed in different proportions using the mixture design method and their enzyme activities were measured, after which the mathematical models between the proportions of different strains and the enzyme activities were established. The results showed the composite consisted of Bacillus tequilensis, Bacillus velezensis, and Bacillus oryzaecorticis, and their optimum ratio was 28.95%: 39.63%: 31.42%. Meanwhile, in the degradation experiment using GW as the carbon source, the maximum enzyme activity of laccase was 47.25 U/L, lignin peroxidase was 66.67 U/L, manganese peroxidase was 99.65 U/L, carboxymethyl cellulase was 90.66 U/mL, and filter paper activity was 48.44 U/mL. The degradation rates of cellulose and lignin on the 18th day could reach 13.48% and 9.73%, respectively. The composite inoculum constructed based on the mixture design showed superior short-term enzyme activity production and biodegradation capacity, which is conducive to the application of GW composting.
To investigate the feasibility of the mixture design methodology applied to the construction of composite inoculum, and the optimization of components to address the current problems of long composting cycles and low wood fiber conversion efficiency of garden waste, the degrading strains from the GW compost samples and their interrelationships were identified, using isolation culture and antagonism experiments. The non-antagonistic strains were mixed in different proportions using the mixture design method and their enzyme activities were measured, after which the mathematical models between the proportions of different strains and the enzyme activities were established. The results showed the composite consisted of Bacillus tequilensis, Bacillus velezensis, and Bacillus oryzaecorticis, and their optimum ratio was 28.95%: 39.63%: 31.42%. Meanwhile, in the degradation experiment using GW as the carbon source, the maximum enzyme activity of laccase was 47.25 U/L, lignin peroxidase was 66.67 U/L, manganese peroxidase was 99.65 U/L, carboxymethyl cellulase was 90.66 U/mL, and filter paper activity was 48.44 U/mL. The degradation rates of cellulose and lignin on the 18th day could reach 13.48% and 9.73%, respectively. The composite inoculum constructed based on the mixture design showed superior short-term enzyme activity production and biodegradation capacity, which is conducive to the application of GW composting.