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2024 Vol. 42, No. 1
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2024, 42(1): 1-8.
doi: 10.13205/j.hjgc.202401001
Abstract:
Anaerobic ammonia oxidation(anammox) is the most promising biological nitrogen removal technology in the wastewater treatment process, and biofilm is an effective means to enrich anammox bacteria. However, the formation of anammox biofilm and the enrichment of anammox bacteria usually takes several months or even longer, which hinders the widespread application of anammox technology. This review summarizes a series of methods to enhance the formation of anammox biofilm and enrich anammox bacteria in recent years, focusing on the effects of the selection of carrier types, carrier surface pretreatment methods, biomass fixation technology, reactor types, anammox bacteria activity, and competitive enhancement on the formation of anammox biofilm and the enrichment of bacteria. Based on clarifying the enhancement strategies, this review elaborates on the advantages, disadvantages, and potential application scenarios of each method, and looks forward to the future research directions of anammox biofilm technology, to provide important references for the optimization and application of anammox processes.
Anaerobic ammonia oxidation(anammox) is the most promising biological nitrogen removal technology in the wastewater treatment process, and biofilm is an effective means to enrich anammox bacteria. However, the formation of anammox biofilm and the enrichment of anammox bacteria usually takes several months or even longer, which hinders the widespread application of anammox technology. This review summarizes a series of methods to enhance the formation of anammox biofilm and enrich anammox bacteria in recent years, focusing on the effects of the selection of carrier types, carrier surface pretreatment methods, biomass fixation technology, reactor types, anammox bacteria activity, and competitive enhancement on the formation of anammox biofilm and the enrichment of bacteria. Based on clarifying the enhancement strategies, this review elaborates on the advantages, disadvantages, and potential application scenarios of each method, and looks forward to the future research directions of anammox biofilm technology, to provide important references for the optimization and application of anammox processes.
2024, 42(1): 9-15.
doi: 10.13205/j.hjgc.202401002
Abstract:
To guarantee the safe and efficient recycling of bottle washing wastewater for the Chinese baijiu industry, wastewater characteristics were analyzed, the risk types and factors of different recycling pathways were identified, and then the control methods also were proposed.Resultsdemonstrated that bottle washing wastewater was with a low level of contamination, and the concentration of pollutants was slightly higher than the corresponding water quality standard. Suspended solids, organic matters, and bacteria were the main risk factors, which could trigger some risks for each recycling situation, such as food safety, health risks from microorganisms, nozzles clogging and damaging equipment, etc. The main reason for the differences in risk is that different recycling pathways have different protection targets and focus on different characteristic pollutants. Suspended solids removal was the necessary control measure for bottle washing wastewater recycling. Removal of organic matters and nutrients, and control of bacterial counts were the key control points for each situation respectively. Bottle washing wastewater should be reused for agriculture irrigation as a priority, followed by industrial cooling, washing and production, miscellaneous use in cities, environmental use in landscapes, and reuse in bottle washing processes. The strategies and measures for bottle washing wastewater reuse for Luzhou were proposed. In the future, we should focus on the full process control of the risk of recycling bottle washing wastewater, broaden the ways of wastewater recycling, and integrate it into the urban water ecological cycle cascade utilization. This paper can provide the theoretical basis and technical reference for the safe recycling of bottle washing wastewater.
To guarantee the safe and efficient recycling of bottle washing wastewater for the Chinese baijiu industry, wastewater characteristics were analyzed, the risk types and factors of different recycling pathways were identified, and then the control methods also were proposed.Resultsdemonstrated that bottle washing wastewater was with a low level of contamination, and the concentration of pollutants was slightly higher than the corresponding water quality standard. Suspended solids, organic matters, and bacteria were the main risk factors, which could trigger some risks for each recycling situation, such as food safety, health risks from microorganisms, nozzles clogging and damaging equipment, etc. The main reason for the differences in risk is that different recycling pathways have different protection targets and focus on different characteristic pollutants. Suspended solids removal was the necessary control measure for bottle washing wastewater recycling. Removal of organic matters and nutrients, and control of bacterial counts were the key control points for each situation respectively. Bottle washing wastewater should be reused for agriculture irrigation as a priority, followed by industrial cooling, washing and production, miscellaneous use in cities, environmental use in landscapes, and reuse in bottle washing processes. The strategies and measures for bottle washing wastewater reuse for Luzhou were proposed. In the future, we should focus on the full process control of the risk of recycling bottle washing wastewater, broaden the ways of wastewater recycling, and integrate it into the urban water ecological cycle cascade utilization. This paper can provide the theoretical basis and technical reference for the safe recycling of bottle washing wastewater.
2024, 42(1): 16-23.
doi: 10.13205/j.hjgc.202401003
Abstract:
One-stage partial nitrification-anammox(PN/A),as an autotrophic nitrogen removal technology, has made the low-carbon treatment of wastewater possible. However, maintaining stable and efficient partial nitrification and increasing the biomass retention of anammox bacteria remain the main challenges for the successful application of the PN/A process. In this study, a novel composite carrier composed of layered silicate minerals and nonwoven fabric was developed to enhance the nitrogen removal performance of the PN/A process. The adsorption characteristics between the carrier and microorganisms, as well as the influence of the composite carrier on the microbial community in the PN/A process, were investigated. The results showed that the reactor with the addition of layered silicate minerals achieved the highest nitrogen removal rate of 131.4 mg/(L·d), which was significantly higher than control group without layered silicate minerals addition(97.2 mg/(L·d)). Surface thermodynamic analysis and the extended DLVO theory indicated that layered silicate minerals formed strong electrostatic attractive forces with the microbial community, promoting microbial adsorption and extracellular polymeric substance secretion. In addition, the surface of the silicate minerals contains abundant metal ion which can promote sludge aggregation and facilitate the retention and growth of anammox bacteria. The hydrotalcite composite carrier provides an effective method for rapid start-up and stable operation of the PN/A process.
One-stage partial nitrification-anammox(PN/A),as an autotrophic nitrogen removal technology, has made the low-carbon treatment of wastewater possible. However, maintaining stable and efficient partial nitrification and increasing the biomass retention of anammox bacteria remain the main challenges for the successful application of the PN/A process. In this study, a novel composite carrier composed of layered silicate minerals and nonwoven fabric was developed to enhance the nitrogen removal performance of the PN/A process. The adsorption characteristics between the carrier and microorganisms, as well as the influence of the composite carrier on the microbial community in the PN/A process, were investigated. The results showed that the reactor with the addition of layered silicate minerals achieved the highest nitrogen removal rate of 131.4 mg/(L·d), which was significantly higher than control group without layered silicate minerals addition(97.2 mg/(L·d)). Surface thermodynamic analysis and the extended DLVO theory indicated that layered silicate minerals formed strong electrostatic attractive forces with the microbial community, promoting microbial adsorption and extracellular polymeric substance secretion. In addition, the surface of the silicate minerals contains abundant metal ion which can promote sludge aggregation and facilitate the retention and growth of anammox bacteria. The hydrotalcite composite carrier provides an effective method for rapid start-up and stable operation of the PN/A process.
2024, 42(1): 24-28.
doi: 10.13205/j.hjgc.202401004
Abstract:
Wastewater regeneration and recycling are essential means for developing unconventional water resources and reducing environmental pollutant discharge. However, in China, the regeneration and reuse efficiencies of wastewater remain low, and the energy and resource consumption for wastewater regeneration are relatively high, and the green circulation system has not yet been formed. This article, therefore, investigates and summarizes the ecological methods for wastewater regeneration from the perspectives of resources, environment, ecology, and safety. It outlines the relationship and implications of ecological treatment and ecologicalization treatment of regenerated water, analyzes the methods and key points for the ecological storage of regenerated water, and defines water quality conditions and environmental impacts for regenerating water resources. It discusses the ecological responses and risks of sensitive biological communities to regenerated water discharge and presents the main pathways to block pollutants' co-exposure risks. This article also elucidates the critical control factors for regenerated water as a key source of ecological water supply in urban surface water bodies, and proposes practical strategies for integrating regenerated water with aquatic ecosystems to promote ecological restoration.
Wastewater regeneration and recycling are essential means for developing unconventional water resources and reducing environmental pollutant discharge. However, in China, the regeneration and reuse efficiencies of wastewater remain low, and the energy and resource consumption for wastewater regeneration are relatively high, and the green circulation system has not yet been formed. This article, therefore, investigates and summarizes the ecological methods for wastewater regeneration from the perspectives of resources, environment, ecology, and safety. It outlines the relationship and implications of ecological treatment and ecologicalization treatment of regenerated water, analyzes the methods and key points for the ecological storage of regenerated water, and defines water quality conditions and environmental impacts for regenerating water resources. It discusses the ecological responses and risks of sensitive biological communities to regenerated water discharge and presents the main pathways to block pollutants' co-exposure risks. This article also elucidates the critical control factors for regenerated water as a key source of ecological water supply in urban surface water bodies, and proposes practical strategies for integrating regenerated water with aquatic ecosystems to promote ecological restoration.
2024, 42(1): 29-36.
doi: 10.13205/j.hjgc.202401005
Abstract:
This study implemented a comprehensive one-year monitoring program to assess the levels of nutrients and antibiotics in both surface water and sediments across diverse locations within Jin'an Lake in Fuzhou. The investigation was primarily directed towards scrutinizing the nuanced spatiotemporal variations induced by conventional pollutants and emerging contaminants, coupled with evaluating the associated ecological risks. The findings unveiled that the total nitrogen concentration in the lake's surface water consistently maintained an elevated status throughout the year(1.88 to 4.96 mg/L), while total phosphorus exhibited heightened concentration during the summer(0.15 to 0.55 mg/L), indicating a state of moderate eutrophication(with a trophic level index ranging from 59.92 to 66.34) during this season. The sediment analysis indicated a total nitrogen content ranging from 30.0 to 1780.0 mg/kg and a total phosphorus content ranging from 81.4 to 2585.0 mg/kg, signifying a condition of moderate to severe eutrophication pollution level. Notably, five antibiotics(sulfamethoxazole, tetracycline, sulfadimoxine, sulfamethoxymethane, and tylosin) were discerned in both surface water and sediments, exhibiting concentrations spanning from 0.49 to 13.03 ng/L and 0.23 to 4.80 ng/g, respectively. The concentrations of antibiotics and associated ecological risks manifested a seasonal disparity, with higher levels observed in winter than in other seasons. Considering the potential co-occurrence of eutrophication and ecological risk within urban artificial lakes, prudent consideration of the spatiotemporal distribution characteristics of conventional pollutants and emerging contaminants is imperative. Moreover, the judicious selection of more productive technologies for the targeted remediation of composite pollution at critical sites emerges as a critical imperative.
This study implemented a comprehensive one-year monitoring program to assess the levels of nutrients and antibiotics in both surface water and sediments across diverse locations within Jin'an Lake in Fuzhou. The investigation was primarily directed towards scrutinizing the nuanced spatiotemporal variations induced by conventional pollutants and emerging contaminants, coupled with evaluating the associated ecological risks. The findings unveiled that the total nitrogen concentration in the lake's surface water consistently maintained an elevated status throughout the year(1.88 to 4.96 mg/L), while total phosphorus exhibited heightened concentration during the summer(0.15 to 0.55 mg/L), indicating a state of moderate eutrophication(with a trophic level index ranging from 59.92 to 66.34) during this season. The sediment analysis indicated a total nitrogen content ranging from 30.0 to 1780.0 mg/kg and a total phosphorus content ranging from 81.4 to 2585.0 mg/kg, signifying a condition of moderate to severe eutrophication pollution level. Notably, five antibiotics(sulfamethoxazole, tetracycline, sulfadimoxine, sulfamethoxymethane, and tylosin) were discerned in both surface water and sediments, exhibiting concentrations spanning from 0.49 to 13.03 ng/L and 0.23 to 4.80 ng/g, respectively. The concentrations of antibiotics and associated ecological risks manifested a seasonal disparity, with higher levels observed in winter than in other seasons. Considering the potential co-occurrence of eutrophication and ecological risk within urban artificial lakes, prudent consideration of the spatiotemporal distribution characteristics of conventional pollutants and emerging contaminants is imperative. Moreover, the judicious selection of more productive technologies for the targeted remediation of composite pollution at critical sites emerges as a critical imperative.
2024, 42(1): 37-46.
doi: 10.13205/j.hjgc.202401006
Abstract:
Membrane bioreactor(MBR) technology, which can combine membrane separation with biological treatment, has advantages of high treatment efficiency, strong adaptability and good application prospects. The basic principle and process type of MBR was briefly introduced in this paper. Besides, impacts of main factors like organic load, sludge concentration, pretreatment, aeration intensity, and temperature were systemically analyzed on the performance of the MBR process. Moreover, the MBR process possesses a great application prospect in municipal wastewater, rural dispersed wastewater, industrial wastewater, seawater desalination, and content recycling, due to easy assembly and a high degree of modularity. Additionally, it is shown that MBR process is mainly used in upgrading large sewage plants, advanced treatment of sewage, and recovery of dispersed sewage in small sewage plants based on practical examples. The existing problems of MBR were also pointed out. Next, the latest research progress of MBR process, including membrane material development, process optimization, new MBR type, microorganisms, process combination, and emerging pollutants were introduced in detail in this paper. At the end of this paper, the future development trends of MBR process were provided as well, pointing out that solving membrane pollution and reducing energy consumption were the research directions for subsequent MBR process optimization.
Membrane bioreactor(MBR) technology, which can combine membrane separation with biological treatment, has advantages of high treatment efficiency, strong adaptability and good application prospects. The basic principle and process type of MBR was briefly introduced in this paper. Besides, impacts of main factors like organic load, sludge concentration, pretreatment, aeration intensity, and temperature were systemically analyzed on the performance of the MBR process. Moreover, the MBR process possesses a great application prospect in municipal wastewater, rural dispersed wastewater, industrial wastewater, seawater desalination, and content recycling, due to easy assembly and a high degree of modularity. Additionally, it is shown that MBR process is mainly used in upgrading large sewage plants, advanced treatment of sewage, and recovery of dispersed sewage in small sewage plants based on practical examples. The existing problems of MBR were also pointed out. Next, the latest research progress of MBR process, including membrane material development, process optimization, new MBR type, microorganisms, process combination, and emerging pollutants were introduced in detail in this paper. At the end of this paper, the future development trends of MBR process were provided as well, pointing out that solving membrane pollution and reducing energy consumption were the research directions for subsequent MBR process optimization.
2024, 42(1): 47-54.
doi: 10.13205/j.hjgc.202401007
Abstract:
Based on the biofilm annular reactor, this study simulated pipe wall biofilm in the chlorine disinfection and chloramine disinfection system. The impact of disinfection(chlorination/chloramination) on the growth characteristics, community composition, and functional abundance of the microbial was explored. The results showed that in comparison with chlorine, the biofilm biomass in the chloramine disinfection system was higher, and the proportion of live bacteria was larger. The community richness and diversity of biofilm under chloramination were higher than that under chlorination. There were significant differences in the community structure of biofilm under the two disinfection methods. Under chlorination, Gammaproteobacteria(63.8%) were predominant, and Nevskia(32.9%) and Methylophilus(20.4%) were the dominant genera; under chloramination, Alphaproteobacteria(53.8%) was the most dominant class, and Bradyrhizobium(10.4%) was the dominant genus. Compared with chloramination, the metabolism functional abundance of the biofilms in the chlorine disinfection system was more advantageous, especially in amino acid metabolism, carbohydrate metabolism, and xenobiotics metabolism. In terms of amino acid metabolism functional pathway, there were significant differences in the functional abundance of tryptophan metabolism, β-alanine metabolism, lysine degradation, and degradation of valine, leucine, and isoleucine for the biofilms under the two disinfection methods.
Based on the biofilm annular reactor, this study simulated pipe wall biofilm in the chlorine disinfection and chloramine disinfection system. The impact of disinfection(chlorination/chloramination) on the growth characteristics, community composition, and functional abundance of the microbial was explored. The results showed that in comparison with chlorine, the biofilm biomass in the chloramine disinfection system was higher, and the proportion of live bacteria was larger. The community richness and diversity of biofilm under chloramination were higher than that under chlorination. There were significant differences in the community structure of biofilm under the two disinfection methods. Under chlorination, Gammaproteobacteria(63.8%) were predominant, and Nevskia(32.9%) and Methylophilus(20.4%) were the dominant genera; under chloramination, Alphaproteobacteria(53.8%) was the most dominant class, and Bradyrhizobium(10.4%) was the dominant genus. Compared with chloramination, the metabolism functional abundance of the biofilms in the chlorine disinfection system was more advantageous, especially in amino acid metabolism, carbohydrate metabolism, and xenobiotics metabolism. In terms of amino acid metabolism functional pathway, there were significant differences in the functional abundance of tryptophan metabolism, β-alanine metabolism, lysine degradation, and degradation of valine, leucine, and isoleucine for the biofilms under the two disinfection methods.
2024, 42(1): 55-62.
doi: 10.13205/j.hjgc.202401008
Abstract:
Emulsion oily wastewater is difficult to treat because of its high concentration of organic pollutants and complex composition. The pulse electric field was used to realize oil-water separation, and persulfate was activated by the pulse electric field to produce SO-4·with strong oxidation, which degrades the organic matter in the demulsified wastewater. The results showed that in the pulsed electric field demulsification experiment, when the power supply voltage was 18 V, the solution pH was 2, the power supply frequency was 800 Hz, the duty ratio was 50%, the distance between the electrode plates was 2.5 cm, and the reaction time was 50 min, the demulsification effect was the best, and the COD(with an initial value of 78340 mg/L) removal rate was as high as 98.03. In the experiment of treatment of demulsified wastewater by pulsed electric field activated PMS, when ρ(PMS)∶ρ(COD)=3, solution pH=2, power supply voltage was 15 V, frequency was 3000 Hz, duty cycle was 70%, electrode spacing was 2.5 cm, and reaction time is 2 h, the degradation rate of organic matters in emulsified oily wastewater is up to 60.8%; Under the same conditions, the degradation rate of pulse power+PMS treatment system is 6.4% higher than that of DC power+PMS treatment system.
Emulsion oily wastewater is difficult to treat because of its high concentration of organic pollutants and complex composition. The pulse electric field was used to realize oil-water separation, and persulfate was activated by the pulse electric field to produce SO-4·with strong oxidation, which degrades the organic matter in the demulsified wastewater. The results showed that in the pulsed electric field demulsification experiment, when the power supply voltage was 18 V, the solution pH was 2, the power supply frequency was 800 Hz, the duty ratio was 50%, the distance between the electrode plates was 2.5 cm, and the reaction time was 50 min, the demulsification effect was the best, and the COD(with an initial value of 78340 mg/L) removal rate was as high as 98.03. In the experiment of treatment of demulsified wastewater by pulsed electric field activated PMS, when ρ(PMS)∶ρ(COD)=3, solution pH=2, power supply voltage was 15 V, frequency was 3000 Hz, duty cycle was 70%, electrode spacing was 2.5 cm, and reaction time is 2 h, the degradation rate of organic matters in emulsified oily wastewater is up to 60.8%; Under the same conditions, the degradation rate of pulse power+PMS treatment system is 6.4% higher than that of DC power+PMS treatment system.
2024, 42(1): 63-71.
doi: 10.13205/j.hjgc.202401009
Abstract:
As an efficient conversion pathway to produce biomass fuel gas, the integrated anaerobic digestion and gasification process shows significant advantages in energy conversion. To ascertain the effect of anaerobic digestion degree on the environmental benefits, a model of gradient-controlled anaerobic digestion and gasification integration process was built, and the distiller's grains were treated with different anaerobic digestion times. The life cycle analysis method and Gabi software were used to conduct the environmental impact assessment.Resultsshowed that the energy produced by the gradient-controlled coupled system can not only cover the drying of the biogas residue, but also achieve net energy output. And the positive environmental impacts based on energy flow can offset the negative environmental impacts based on material flow, so that the system can obtain positive comprehensive environmental impacts. The optimal total potential environmental impact of a 1000 kg distiller's grains system was-2.02×10-9 with anaerobic digestion treatment lasting for 8 days. The control of the coupling degree of anaerobic digestion and gasification process makes the coupled system optimize its net energy output and have the most favorable environmental impact, so as to provide theoretical guidance for the application of the coupled process.
As an efficient conversion pathway to produce biomass fuel gas, the integrated anaerobic digestion and gasification process shows significant advantages in energy conversion. To ascertain the effect of anaerobic digestion degree on the environmental benefits, a model of gradient-controlled anaerobic digestion and gasification integration process was built, and the distiller's grains were treated with different anaerobic digestion times. The life cycle analysis method and Gabi software were used to conduct the environmental impact assessment.Resultsshowed that the energy produced by the gradient-controlled coupled system can not only cover the drying of the biogas residue, but also achieve net energy output. And the positive environmental impacts based on energy flow can offset the negative environmental impacts based on material flow, so that the system can obtain positive comprehensive environmental impacts. The optimal total potential environmental impact of a 1000 kg distiller's grains system was-2.02×10-9 with anaerobic digestion treatment lasting for 8 days. The control of the coupling degree of anaerobic digestion and gasification process makes the coupled system optimize its net energy output and have the most favorable environmental impact, so as to provide theoretical guidance for the application of the coupled process.
2024, 42(1): 72-78.
doi: 10.13205/j.hjgc.202401010
Abstract:
With the development of technology, digital and intelligent technologies are playing increasingly critical roles in economic and social development. China has proposed a series of strategies to promote digital and intelligent transformation in various industries, to drive economic development and achieve sustainable development. The steel industry generates a large amount of dust during production, which poses a severe threat to the environment and human health. The dust removal system, as an important component of environmental protection equipment in the steel industry, still has a low level of digital intelligence. Based on the actual needs of operation and management, this project combines information network platforms and big data analysis technology to develop intelligent fault monitoring and diagnosis technologies for dust removal systems, including data collection and transmission technology for the dust removal system, automatic visual inspection technology for the scraper ash conveying system, intelligent pulse valve spraying control and bag leak diagnosis and location system, intelligent diagnosis technology for fan faults, and intelligent inspection and diagnosis technology for electrical rooms. These technologies have been applied in the project of the Zhanjiang Plant of Baosteel Corp. This technology improves the efficiency of equipment maintenance and reduces the maintenance costs, enhances the safety and stability of equipment operation, further realizes the scientific, intelligent, and refined operation management of the environmental dust removal system, and enhances the market competitiveness of enterprises.
With the development of technology, digital and intelligent technologies are playing increasingly critical roles in economic and social development. China has proposed a series of strategies to promote digital and intelligent transformation in various industries, to drive economic development and achieve sustainable development. The steel industry generates a large amount of dust during production, which poses a severe threat to the environment and human health. The dust removal system, as an important component of environmental protection equipment in the steel industry, still has a low level of digital intelligence. Based on the actual needs of operation and management, this project combines information network platforms and big data analysis technology to develop intelligent fault monitoring and diagnosis technologies for dust removal systems, including data collection and transmission technology for the dust removal system, automatic visual inspection technology for the scraper ash conveying system, intelligent pulse valve spraying control and bag leak diagnosis and location system, intelligent diagnosis technology for fan faults, and intelligent inspection and diagnosis technology for electrical rooms. These technologies have been applied in the project of the Zhanjiang Plant of Baosteel Corp. This technology improves the efficiency of equipment maintenance and reduces the maintenance costs, enhances the safety and stability of equipment operation, further realizes the scientific, intelligent, and refined operation management of the environmental dust removal system, and enhances the market competitiveness of enterprises.
2024, 42(1): 79-84.
doi: 10.13205/j.hjgc.202401011
Abstract:
Identifying the abnormal phenomenon of pollutant emission data caused by subjective tampering or abnormal equipment working conditions is of great significance for environmental pollution monitoring, remediation and management of key pollutant discharging units. Taking a steel enterprise in Hebei Province as an example, we developed a prediction model, TabNet, based on hourly working condition data and smoke concentration. We trained the model by using an improved loss function, MSECorrLoss. TabNet was compared with XGBoost, LightGBM and BiLSTM. We developed a K-error anomaly detection algorithm to identify the anomaly data of smoke emission. The results show that: 1) the MAPE of TabNet model decreases from 15.33% to 15.10% and TabNet model converges faster after being trained by improved MSECorrLoss comparing with being trained by RMSELoss loss function. 2) LightGBM and XGBoost have high training speed, but low prediction accuracy(RMSE=0.3201, MAPE=29.45%). The robustness and stability of XGBoost and BiLSTM models(RMSE: 0.3403~0.3425, MAPE: 13.58%~18.38%) is lower than TabNet(RMSE: 0.2886~0.2934, MAPE: 15.10%~15.33%). Although TabNet takes longer training time, it does not require manual feature selection, has low application restrictions, and has a better application performance in smoke prediction. 3) The TabNet model constructed based on working condition data has high prediction accuracy and stability in pollutant discharge prediction. With K-error detection, the TabNet model overcomes the subjectivity brought by a threshold method. This method can detect the abnormal data of pollutant discharge quickly and support environmental management decision making.
Identifying the abnormal phenomenon of pollutant emission data caused by subjective tampering or abnormal equipment working conditions is of great significance for environmental pollution monitoring, remediation and management of key pollutant discharging units. Taking a steel enterprise in Hebei Province as an example, we developed a prediction model, TabNet, based on hourly working condition data and smoke concentration. We trained the model by using an improved loss function, MSECorrLoss. TabNet was compared with XGBoost, LightGBM and BiLSTM. We developed a K-error anomaly detection algorithm to identify the anomaly data of smoke emission. The results show that: 1) the MAPE of TabNet model decreases from 15.33% to 15.10% and TabNet model converges faster after being trained by improved MSECorrLoss comparing with being trained by RMSELoss loss function. 2) LightGBM and XGBoost have high training speed, but low prediction accuracy(RMSE=0.3201, MAPE=29.45%). The robustness and stability of XGBoost and BiLSTM models(RMSE: 0.3403~0.3425, MAPE: 13.58%~18.38%) is lower than TabNet(RMSE: 0.2886~0.2934, MAPE: 15.10%~15.33%). Although TabNet takes longer training time, it does not require manual feature selection, has low application restrictions, and has a better application performance in smoke prediction. 3) The TabNet model constructed based on working condition data has high prediction accuracy and stability in pollutant discharge prediction. With K-error detection, the TabNet model overcomes the subjectivity brought by a threshold method. This method can detect the abnormal data of pollutant discharge quickly and support environmental management decision making.
2024, 42(1): 85-94.
doi: 10.13205/j.hjgc.202401012
Abstract:
Single non-thermal plasma technology(NTP) and single wet heterogeneous catalytic technology for the degradation of VOCs suffer from the problems of O3 emission and the need for continuous oxidant supply, respectively. To overcome the single technology bottleneck, this study combines NTP with wet heterogeneous catalytic technology for the degradation of chlorobenzene(CB), using NTP by-product O3 as the oxidant source for the wet system to achieve deep mineralization of CB. Activated carbon(AC) was used as the support for the heterogeneous catalyst, and a surface loaded with different metal fractions was injected into the wet reactor. Experimental results showed that the NTP-coupled liquid-phase heterogeneous system significantly improved the degradation of chlorobenzene(CB), compared to a single NTP. The best CB degradation performance was obtained for the coupled system when Fe was used as the active component, the Fe-C catalyst was injected at a dosage of 1 g/L, the initial pH of the solution was 7, and the supply voltage was 14 kV, and the CB removal efficiency and mineralization rate reached 81.4% and 48%, respectively. Fe-C injection increased the CB absorption mass transfer coefficient in the liquid phase from 0.0280 s-1 to 0.1207 s-1, resulting in a mass transfer enhancement factor of 9.81 for the catalytic process. Finally, the CB degradation pathway was deduced from the intermediates of each system.
Single non-thermal plasma technology(NTP) and single wet heterogeneous catalytic technology for the degradation of VOCs suffer from the problems of O3 emission and the need for continuous oxidant supply, respectively. To overcome the single technology bottleneck, this study combines NTP with wet heterogeneous catalytic technology for the degradation of chlorobenzene(CB), using NTP by-product O3 as the oxidant source for the wet system to achieve deep mineralization of CB. Activated carbon(AC) was used as the support for the heterogeneous catalyst, and a surface loaded with different metal fractions was injected into the wet reactor. Experimental results showed that the NTP-coupled liquid-phase heterogeneous system significantly improved the degradation of chlorobenzene(CB), compared to a single NTP. The best CB degradation performance was obtained for the coupled system when Fe was used as the active component, the Fe-C catalyst was injected at a dosage of 1 g/L, the initial pH of the solution was 7, and the supply voltage was 14 kV, and the CB removal efficiency and mineralization rate reached 81.4% and 48%, respectively. Fe-C injection increased the CB absorption mass transfer coefficient in the liquid phase from 0.0280 s-1 to 0.1207 s-1, resulting in a mass transfer enhancement factor of 9.81 for the catalytic process. Finally, the CB degradation pathway was deduced from the intermediates of each system.
2024, 42(1): 95-101.
doi: 10.13205/j.hjgc.202401013
Abstract:
To explore the effects of garden waste compost on saline soil properties and carbon sequestration, field experiments were conducted using three treatments: garden waste compost(T1), a mixture of garden waste compost and bentonite(T2), and a non-amended control(CK). Changes in soil pH, EC, total porosity, saturated hydraulic conductivity, available nitrogen, phosphorus, and potassium, organic carbon storage(ΔSOC), microbial biomass carbon(MBC), and microbial community were analyzed. The results showed that composting garden waste can reduce carbon emissions by 53% compared to traditional incineration. Additionally, the application of garden waste compost can increase ΔSOC by 5 to 24 times. The soil bulk density and EC of T1 and T2 were significantly lower than CK, while the total porosity and saturated hydraulic conductivity were significantly higher than CK. T2 had the highest nutrient content, with soil organic matter and available nitrogen twice as high as those in the CK group. The mixed application of compost and bentonite significantly increased soil nutrient content, with an improvement effect significantly higher than that of other treatments. The application of garden waste compost can also change the microbial community structure. The main dominant bacteria included Proteobacteria, Actinomycetes, Bacteroidetes, Chloroflexi, Gemmatimonadetes, and Acidobacteria. Among the fungi, Ascomycota, Basidiomycota, Chytridiomycota, and Mortierella were dominant. Pearson correlation analysis also showed that Acidobacteria and Actinomycetes were significantly positively correlated with organic carbon, microbial biomass carbon, and soil nutrients, and significantly negatively correlated with soil salinity and bulk density.
To explore the effects of garden waste compost on saline soil properties and carbon sequestration, field experiments were conducted using three treatments: garden waste compost(T1), a mixture of garden waste compost and bentonite(T2), and a non-amended control(CK). Changes in soil pH, EC, total porosity, saturated hydraulic conductivity, available nitrogen, phosphorus, and potassium, organic carbon storage(ΔSOC), microbial biomass carbon(MBC), and microbial community were analyzed. The results showed that composting garden waste can reduce carbon emissions by 53% compared to traditional incineration. Additionally, the application of garden waste compost can increase ΔSOC by 5 to 24 times. The soil bulk density and EC of T1 and T2 were significantly lower than CK, while the total porosity and saturated hydraulic conductivity were significantly higher than CK. T2 had the highest nutrient content, with soil organic matter and available nitrogen twice as high as those in the CK group. The mixed application of compost and bentonite significantly increased soil nutrient content, with an improvement effect significantly higher than that of other treatments. The application of garden waste compost can also change the microbial community structure. The main dominant bacteria included Proteobacteria, Actinomycetes, Bacteroidetes, Chloroflexi, Gemmatimonadetes, and Acidobacteria. Among the fungi, Ascomycota, Basidiomycota, Chytridiomycota, and Mortierella were dominant. Pearson correlation analysis also showed that Acidobacteria and Actinomycetes were significantly positively correlated with organic carbon, microbial biomass carbon, and soil nutrients, and significantly negatively correlated with soil salinity and bulk density.
2024, 42(1): 102-109.
doi: 10.13205/j.hjgc.202401014
Abstract:
Under the goal of low carbon, the resource utilization of waste-activated sludge is an important approach to synergistically realize the pollution reduction and carbon reduction of organic solid waste in sewage treatment plants. Anaerobic co-fermentation technology is one of the most effective strategies to realize waste-activated sludge resource utilization. High-value products such as volatile fatty acids obtained by anaerobic co-fermentation of waste-activated sludge and other organic solid wastes can be widely used in the production of industrial products, which can simultaneously reduce carbon emissions and realize resource utilization. However, the existing studies mainly focus on the discussion of acid production efficiency during co-fermentation, and lack a systematic summary and analysis of the mechanism and optimal regulation methods. Therefore, based on previous studies, this paper systematically analyzed acid production efficiency from anaerobic co-fermentation of waste-activated sludge with food waste and agricultural waste, discussed the influence of technological parameters such as C/N ratio, pH, temperature, and sludge residence time, and proposed the downstream application of volatile fatty acids. Meanwhile, the work also prospected the perspective of anaerobic co-fermentation technology of waste-activated sludge from the aspects of energy and economy. This work would provide the theoretical basis and technical guidance for the low carbonization application of waste-activated sludge anaerobic co-fermentation technology.
Under the goal of low carbon, the resource utilization of waste-activated sludge is an important approach to synergistically realize the pollution reduction and carbon reduction of organic solid waste in sewage treatment plants. Anaerobic co-fermentation technology is one of the most effective strategies to realize waste-activated sludge resource utilization. High-value products such as volatile fatty acids obtained by anaerobic co-fermentation of waste-activated sludge and other organic solid wastes can be widely used in the production of industrial products, which can simultaneously reduce carbon emissions and realize resource utilization. However, the existing studies mainly focus on the discussion of acid production efficiency during co-fermentation, and lack a systematic summary and analysis of the mechanism and optimal regulation methods. Therefore, based on previous studies, this paper systematically analyzed acid production efficiency from anaerobic co-fermentation of waste-activated sludge with food waste and agricultural waste, discussed the influence of technological parameters such as C/N ratio, pH, temperature, and sludge residence time, and proposed the downstream application of volatile fatty acids. Meanwhile, the work also prospected the perspective of anaerobic co-fermentation technology of waste-activated sludge from the aspects of energy and economy. This work would provide the theoretical basis and technical guidance for the low carbonization application of waste-activated sludge anaerobic co-fermentation technology.
2024, 42(1): 110-118.
doi: 10.13205/j.hjgc.202401015
Abstract:
The study on pyrolysis characteristics of plastic waste is in favor of achieving its clean and efficient conversion and utilization. The catalytic pyrolysis characteristics of high-density polyethylene(HDPE), low-density polyethylene(LDPE), and polypropylene(PP), with three different catalysts of HZSM-5,Hβ and HUSY, were investigated by the thermogravimetric experiments at different heating rates of 10, 20, 30,40,50 ℃/min. The increase of heating rate caused thermal hysteresis, and the different types of catalysts had different effects on the improvement of pyrolysis rates of the HDPE, LDPE, and PP. In order to provide theoretical support, three kinetic modeling analysis methods, including Coats-Redfern(CR), Flynn-Wall-Ozawa(FWO), and distributed activation energy model(DAEM), were used to calculate the kinetic parameters of HDPE, LDPE, and PP pyrolysis under different conditions. CR method verified that each pyrolysis reaction was following the first-order reaction model and found that the catalysts could significantly reduce the activation energy of the reaction. The calculated activation energy by two iso-conversion rate methods, including the FWO method and DAEM, was similar to each other. The DAEM model, including the kinetic compensation effect, showed that the activation energy increased and then decreased as the conversion rate(α) increases, and reached the highest at α=40%~50%.
The study on pyrolysis characteristics of plastic waste is in favor of achieving its clean and efficient conversion and utilization. The catalytic pyrolysis characteristics of high-density polyethylene(HDPE), low-density polyethylene(LDPE), and polypropylene(PP), with three different catalysts of HZSM-5,Hβ and HUSY, were investigated by the thermogravimetric experiments at different heating rates of 10, 20, 30,40,50 ℃/min. The increase of heating rate caused thermal hysteresis, and the different types of catalysts had different effects on the improvement of pyrolysis rates of the HDPE, LDPE, and PP. In order to provide theoretical support, three kinetic modeling analysis methods, including Coats-Redfern(CR), Flynn-Wall-Ozawa(FWO), and distributed activation energy model(DAEM), were used to calculate the kinetic parameters of HDPE, LDPE, and PP pyrolysis under different conditions. CR method verified that each pyrolysis reaction was following the first-order reaction model and found that the catalysts could significantly reduce the activation energy of the reaction. The calculated activation energy by two iso-conversion rate methods, including the FWO method and DAEM, was similar to each other. The DAEM model, including the kinetic compensation effect, showed that the activation energy increased and then decreased as the conversion rate(α) increases, and reached the highest at α=40%~50%.
2024, 42(1): 119-125.
doi: 10.13205/j.hjgc.202401016
Abstract:
The solid waste, such as sintering machine head ash generated by steel enterprises has a high potassium content. If it is directly returned as ironmaking raw materials for sintering and recycling without treatment, it will not only affect the quality of sintered ore, but also lead to problems such as an increase in coke ratio and obstruction in the blast furnace ironmaking process. At the same time, China's potassium ore reserves are insufficient, and the external dependence of potash is higher than 1/2. Given the above problems, this paper first introduces the treatment of iron and steel dust and the production and consumption status of potassium salt, and deeply analyzes the impact of potassium dust removal as sintering raw material on the ironmaking process. After that, the dust removal process of the rotary kiln and rotary hearth furnace is introduced, which also leads to the enrichment of potassium in the secondary zinc dust. Finally, based on the physical and chemical properties and the existing state of potassium-containing substances in the dust, the research progress of potassium extraction from the potassium-containing dust by two processes of “flotation gravity separation” and “water leaching-separation-purification-crystallization” is introduced. If the potassium-containing dust from the sintering process and the secondary zinc dust from the rotary hearth furnace are all recycled for KCl, it is expected to reduce the external dependence proportion of KCl in China by about 20%.
The solid waste, such as sintering machine head ash generated by steel enterprises has a high potassium content. If it is directly returned as ironmaking raw materials for sintering and recycling without treatment, it will not only affect the quality of sintered ore, but also lead to problems such as an increase in coke ratio and obstruction in the blast furnace ironmaking process. At the same time, China's potassium ore reserves are insufficient, and the external dependence of potash is higher than 1/2. Given the above problems, this paper first introduces the treatment of iron and steel dust and the production and consumption status of potassium salt, and deeply analyzes the impact of potassium dust removal as sintering raw material on the ironmaking process. After that, the dust removal process of the rotary kiln and rotary hearth furnace is introduced, which also leads to the enrichment of potassium in the secondary zinc dust. Finally, based on the physical and chemical properties and the existing state of potassium-containing substances in the dust, the research progress of potassium extraction from the potassium-containing dust by two processes of “flotation gravity separation” and “water leaching-separation-purification-crystallization” is introduced. If the potassium-containing dust from the sintering process and the secondary zinc dust from the rotary hearth furnace are all recycled for KCl, it is expected to reduce the external dependence proportion of KCl in China by about 20%.
2024, 42(1): 126-134.
doi: 10.13205/j.hjgc.202401017
Abstract:
This study intends to effectively improve the efficiency of sludge lysis and reduce the yield of excess sludge through hydrodynamic cavitation combined with ozone. To reveal the synergism of hydrodynamic cavitation/O3 treatment, a suite of analysis was implemented: sludge concentration, the content of organic matter, the destruction and three-dimensional excitation-emission matrix spectra of EPS, the particle size of sludge flocs and microphotograph of sludge. When the ozone concentration and operation time was(160±10) g/m3 and 135 min, the removal rates of VSS and TSS reached 79.12% and 68.55%, respectively, DDCOD reached 90.67%, NH+4-N increased from(3.15±0.07) mg/L to(42.75±0.21) mg/L, total protein and polysaccharide content in the sludge supernatant increased by 627.05% and 957.28%, respectively. From the change of particle size distribution of sludge and the observation of floc structure under the microscope, it was concluded that the particles of sludge flocs are significantly smaller than the raw sludge, by pretreatment of hydrodynamic cavitation combined with ozonation. The analysis of three-dimensional fluorescence results showed that this method enhanced the effect of sludge lysis and the hydrodynamic cavitation/O3 pretreatment showed a significant synergistic effect in enhancing sludge lysis.
This study intends to effectively improve the efficiency of sludge lysis and reduce the yield of excess sludge through hydrodynamic cavitation combined with ozone. To reveal the synergism of hydrodynamic cavitation/O3 treatment, a suite of analysis was implemented: sludge concentration, the content of organic matter, the destruction and three-dimensional excitation-emission matrix spectra of EPS, the particle size of sludge flocs and microphotograph of sludge. When the ozone concentration and operation time was(160±10) g/m3 and 135 min, the removal rates of VSS and TSS reached 79.12% and 68.55%, respectively, DDCOD reached 90.67%, NH+4-N increased from(3.15±0.07) mg/L to(42.75±0.21) mg/L, total protein and polysaccharide content in the sludge supernatant increased by 627.05% and 957.28%, respectively. From the change of particle size distribution of sludge and the observation of floc structure under the microscope, it was concluded that the particles of sludge flocs are significantly smaller than the raw sludge, by pretreatment of hydrodynamic cavitation combined with ozonation. The analysis of three-dimensional fluorescence results showed that this method enhanced the effect of sludge lysis and the hydrodynamic cavitation/O3 pretreatment showed a significant synergistic effect in enhancing sludge lysis.
2024, 42(1): 135-143.
doi: 10.13205/j.hjgc.202401018
Abstract:
The baijiu industry has witnessed a long-existing challenge for recycling the distillers' grains(DG) to minimize its impact on the environment. A new thermochemical technology is developed for DG disposal by recovering materials and energy, defined as the new technology. This research used materials/energy flow analysis and life cycle assessment to evaluate the environmental impacts of this new technology under different scenarios. The key findings, as compared with the traditional technology are as follows: 1) the new technology, in large part, will contribute remarkable environmental benefits for the whole baijiu production process while considering seven typical life cycle environmental impact categories, and in particular, the global warming impacts will decrease by 40% to 60%. 2) the new technology will bring additional environmental burden in three categories, including 9% in human being toxicity, 26% in marine aquatic ecotoxicity, and 73% in terrestrial biological toxicity. The reason is that the new technology has electricity consumption 19 times that of the traditional technology. The new system has higher impacts in 10 categories when the new technology generates hot water than that generates steam, of which global warming impacts increase by 49%. Based on the assessment result, there are three methods to dramatically decrease the holistic environmental impacts of Baijiu production: 1) producing steam rather than hot water by using recovery thermochemical waste heat in the new DG disposal process; 2) using a natural gas boiler instead of an electric boiler; 3) upgrading the energy-saving facility and energy-intensive processes during scaling up.
The baijiu industry has witnessed a long-existing challenge for recycling the distillers' grains(DG) to minimize its impact on the environment. A new thermochemical technology is developed for DG disposal by recovering materials and energy, defined as the new technology. This research used materials/energy flow analysis and life cycle assessment to evaluate the environmental impacts of this new technology under different scenarios. The key findings, as compared with the traditional technology are as follows: 1) the new technology, in large part, will contribute remarkable environmental benefits for the whole baijiu production process while considering seven typical life cycle environmental impact categories, and in particular, the global warming impacts will decrease by 40% to 60%. 2) the new technology will bring additional environmental burden in three categories, including 9% in human being toxicity, 26% in marine aquatic ecotoxicity, and 73% in terrestrial biological toxicity. The reason is that the new technology has electricity consumption 19 times that of the traditional technology. The new system has higher impacts in 10 categories when the new technology generates hot water than that generates steam, of which global warming impacts increase by 49%. Based on the assessment result, there are three methods to dramatically decrease the holistic environmental impacts of Baijiu production: 1) producing steam rather than hot water by using recovery thermochemical waste heat in the new DG disposal process; 2) using a natural gas boiler instead of an electric boiler; 3) upgrading the energy-saving facility and energy-intensive processes during scaling up.
2024, 42(1): 144-149.
doi: 10.13205/j.hjgc.202401019
Abstract:
Sponge city construction is an important measure for urban non-point source pollution control and waterlogging prevention, which has been widely extended in China. To quantify the environmental and economic impacts of the construction and operation stages of sponge city source facilities, aiming at the shortcomings of the current global research on the environmental and economic benefits in sponge city, 5 typical source facilities in a school site were selected as the examples to quantitatively analyze the environmental and economic impacts and benefits and identify key influencing factors by life cycle assessment(LCA) and life cycle costing(LCC) integrated evaluation method(LCA-LCC). The results presented that the construction stage could generate high environmental impact and economic cost, while the operation stage could generate significant environmental and economic benefits. In the operational phase, the payback period of the total environmental impact on runoff and water quality control was within 8 years, and the payback period of total economic cost was within 2 years, and the overall benefits of sponge city source facilities were considerable.
Sponge city construction is an important measure for urban non-point source pollution control and waterlogging prevention, which has been widely extended in China. To quantify the environmental and economic impacts of the construction and operation stages of sponge city source facilities, aiming at the shortcomings of the current global research on the environmental and economic benefits in sponge city, 5 typical source facilities in a school site were selected as the examples to quantitatively analyze the environmental and economic impacts and benefits and identify key influencing factors by life cycle assessment(LCA) and life cycle costing(LCC) integrated evaluation method(LCA-LCC). The results presented that the construction stage could generate high environmental impact and economic cost, while the operation stage could generate significant environmental and economic benefits. In the operational phase, the payback period of the total environmental impact on runoff and water quality control was within 8 years, and the payback period of total economic cost was within 2 years, and the overall benefits of sponge city source facilities were considerable.
2024, 42(1): 150-156.
doi: 10.13205/j.hjgc.202401020
Abstract:
To evaluate the impact of the external water inflow on the urban drainage pressure in a city in Shandong Province, a one-dimensional and two-dimensional combined model was established on InfoWorks ICM to analyze the drainage capacity and flooding distribution in the urban under different rainfall conditions. Then the optimization schemes were proposed. The results showed that the inflow of external water was the main reason for the drainage pipe network overloading, nodes overflowing, and flooding in the main urban area of the city. More than half of the pipes were overloaded under the design rainfall recurrence of 2 a and 3 a with a duration of 2 h, and the overflow nodes accounted for 1.38% and 3.1%, respectively. The proportion of flooded areas was 35.9% and 38.7% under the design rainfall recurrence of 20 a and 30 a with a duration of 24 h, respectively, among which 9.60% and 9.94% of the area were posted at high risk. Considering both economy and effectiveness, the construction of surface culverts and flood discharge ditches was adopted to intercept surface runoff and alleviate the drainage pressure of urban pipeline networks. The optimized plan can effectively reduce the flooded areas in urban under external water inflow, especially for high-risk areas. The high-risk area was reduced by 75% and 71% under the design rainfall recurrence of 20 a and 30 a with a duration of 24 h, respectively, and the maximum flooding depth decreased to 1 meter below.
To evaluate the impact of the external water inflow on the urban drainage pressure in a city in Shandong Province, a one-dimensional and two-dimensional combined model was established on InfoWorks ICM to analyze the drainage capacity and flooding distribution in the urban under different rainfall conditions. Then the optimization schemes were proposed. The results showed that the inflow of external water was the main reason for the drainage pipe network overloading, nodes overflowing, and flooding in the main urban area of the city. More than half of the pipes were overloaded under the design rainfall recurrence of 2 a and 3 a with a duration of 2 h, and the overflow nodes accounted for 1.38% and 3.1%, respectively. The proportion of flooded areas was 35.9% and 38.7% under the design rainfall recurrence of 20 a and 30 a with a duration of 24 h, respectively, among which 9.60% and 9.94% of the area were posted at high risk. Considering both economy and effectiveness, the construction of surface culverts and flood discharge ditches was adopted to intercept surface runoff and alleviate the drainage pressure of urban pipeline networks. The optimized plan can effectively reduce the flooded areas in urban under external water inflow, especially for high-risk areas. The high-risk area was reduced by 75% and 71% under the design rainfall recurrence of 20 a and 30 a with a duration of 24 h, respectively, and the maximum flooding depth decreased to 1 meter below.
2024, 42(1): 157-165.
doi: 10.13205/j.hjgc.202401021
Abstract:
A series of smectite-supported sulfidized nanoscale zero-valent iron(CSZVI) was synthesized by a one-step method. The surface physicochemical properties and material structure of CSZVI were characterized using TEM, BET, XRD, XPS, and contact angle meter, focusing on the effect of the n(S)/n(Fe) on the removal of organic pollutants by CSZVI. The results showed that smectite effectively inhibited the aggregation and reduced the particle size of sulfidized nanoscale zero-valent iron(SnZVI); CSZVI exhibited the highest reactivity at m(smectite)/m(Fe) of 5, and the degradation efficiency of florfenicol(FF) reached 100% within 15 min; at a S/Fe molar ratio of 0.112, CSZVI exhibited the highest reactivity toward 2,4-dinitrotoluene(DNT), p-nitrophenol(PNP), florfenicol(FF), and chloramphenicol(CAP), and the reactivity of CSZVI decreased with the increase of n(S)/n(Fe) molar ratio; increasing n(S)/n(Fe)resulted in greater inhibition on the degradation of hydrophilic PNP and smaller inhibition on the degradation of hydrophobic FF in the cosolvent with V(water)/V(ethanol)=7∶3 than in the aqueous phase. The results demonstrated that an increase in n(S)/n(Fe) enhances the surface hydrophobicity of CSZVI, which increases the degradation efficiency for hydrophobic pollutants and decreases the degradation efficiency for hydrophilic pollutants.
A series of smectite-supported sulfidized nanoscale zero-valent iron(CSZVI) was synthesized by a one-step method. The surface physicochemical properties and material structure of CSZVI were characterized using TEM, BET, XRD, XPS, and contact angle meter, focusing on the effect of the n(S)/n(Fe) on the removal of organic pollutants by CSZVI. The results showed that smectite effectively inhibited the aggregation and reduced the particle size of sulfidized nanoscale zero-valent iron(SnZVI); CSZVI exhibited the highest reactivity at m(smectite)/m(Fe) of 5, and the degradation efficiency of florfenicol(FF) reached 100% within 15 min; at a S/Fe molar ratio of 0.112, CSZVI exhibited the highest reactivity toward 2,4-dinitrotoluene(DNT), p-nitrophenol(PNP), florfenicol(FF), and chloramphenicol(CAP), and the reactivity of CSZVI decreased with the increase of n(S)/n(Fe) molar ratio; increasing n(S)/n(Fe)resulted in greater inhibition on the degradation of hydrophilic PNP and smaller inhibition on the degradation of hydrophobic FF in the cosolvent with V(water)/V(ethanol)=7∶3 than in the aqueous phase. The results demonstrated that an increase in n(S)/n(Fe) enhances the surface hydrophobicity of CSZVI, which increases the degradation efficiency for hydrophobic pollutants and decreases the degradation efficiency for hydrophilic pollutants.
2024, 42(1): 166-176.
doi: 10.13205/j.hjgc.202401022
Abstract:
Emerging contaminants(ECs) are biotoxic, environmentally persistent, and bio-accumulative in soil, and are widely present in contaminated sites in China. This paper reviews the current research status, migration and transformation mechanisms, and remediation processes of new contaminants in contaminated site soils, discusses in detail the sources and biotoxicity of typical new contaminants in soils, and looks into the future of new contaminant remediation at contaminated sites in China. It is expected to provide a reference for future in-depth research on the whole chain of new pollutant detection-metabolism pathway-soil remediation technology, and the theoretical basis of new pollutant treatment, and to promote the development of the related practical application.
Emerging contaminants(ECs) are biotoxic, environmentally persistent, and bio-accumulative in soil, and are widely present in contaminated sites in China. This paper reviews the current research status, migration and transformation mechanisms, and remediation processes of new contaminants in contaminated site soils, discusses in detail the sources and biotoxicity of typical new contaminants in soils, and looks into the future of new contaminant remediation at contaminated sites in China. It is expected to provide a reference for future in-depth research on the whole chain of new pollutant detection-metabolism pathway-soil remediation technology, and the theoretical basis of new pollutant treatment, and to promote the development of the related practical application.
2024, 42(1): 177-183.
doi: 10.13205/j.hjgc.202401023
Abstract:
Several remediation technologies have been exploited and developed to remove petroleum hydrocarbons, a typical pollutant in the petrochemical industry. Bio-remediation has been considered an appropriate one to treat the in-service sites for its advantages in difficulty, cost, and security. Nevertheless, the application of this technology was still restricted by tedious periods and limited efficiency. Thus, 4 kinds of solubilizers were designed and tested in this paper. To all solubilizers, the critical micelle concentration(CMC) was determined within 100~120 mg/kg and the corresponding surface tension was around 30 mN/m. In a typical soil-flushing process, the total petroleum hydrocarbons(TPHs) could be decreased from 27000 mg/kg to 4500 mg/kg or less by LIS-1, LAS-1, and LIS-2, and the TPH removal was proved to depend mainly on the ratio of solubilizers to the polluted soil. The intensification of the solubilizer was confirmed by the micro-biological degradation process, and the results were proved consistent with that of the soil-flushing process. Further, such consistency could help reduce the design period of more new types of solubilizers and improve the development efficiency of soil solubilization technology.
Several remediation technologies have been exploited and developed to remove petroleum hydrocarbons, a typical pollutant in the petrochemical industry. Bio-remediation has been considered an appropriate one to treat the in-service sites for its advantages in difficulty, cost, and security. Nevertheless, the application of this technology was still restricted by tedious periods and limited efficiency. Thus, 4 kinds of solubilizers were designed and tested in this paper. To all solubilizers, the critical micelle concentration(CMC) was determined within 100~120 mg/kg and the corresponding surface tension was around 30 mN/m. In a typical soil-flushing process, the total petroleum hydrocarbons(TPHs) could be decreased from 27000 mg/kg to 4500 mg/kg or less by LIS-1, LAS-1, and LIS-2, and the TPH removal was proved to depend mainly on the ratio of solubilizers to the polluted soil. The intensification of the solubilizer was confirmed by the micro-biological degradation process, and the results were proved consistent with that of the soil-flushing process. Further, such consistency could help reduce the design period of more new types of solubilizers and improve the development efficiency of soil solubilization technology.
2024, 42(1): 184-190.
doi: 10.13205/j.hjgc.202401024
Abstract:
To study the inducing effects of different concentrations of benzene on the oil-degrading bacterium R. erythropolis KB1, characterize the benzene-induced VBNC state of the bacterial cells, and physiological and biochemical characteristics of bacterial cells, and petroleum degradation ability of the resuscitated R. erythropolis cells, R. erythropolis KB1 was cultured in LB medium and basal medium. The formation of the VBNC state of R. erythropolis KB1 cells induced by benzene was observed by spectrophotometry, scanning electron microscopy, and transmission electron microscopy, and the oil degradation abilities of the resuscitated bacterial cells were determined by infrared spectrophotometry. The results showed that when the concentration of benzene in the culture medium was 2.5% above, the growth of R. erythropolis KB1 could be effectively inhibited. After being cultured for 6 h, R. erythropolis KB1 cells entered the VBNC state. The VBNC cells could be resuscitated into the culturable state under certain conditions. The resuscitated bacterial cells showed good adaptabilities to the environments, and their oil degradation ability was not changed obviously.
To study the inducing effects of different concentrations of benzene on the oil-degrading bacterium R. erythropolis KB1, characterize the benzene-induced VBNC state of the bacterial cells, and physiological and biochemical characteristics of bacterial cells, and petroleum degradation ability of the resuscitated R. erythropolis cells, R. erythropolis KB1 was cultured in LB medium and basal medium. The formation of the VBNC state of R. erythropolis KB1 cells induced by benzene was observed by spectrophotometry, scanning electron microscopy, and transmission electron microscopy, and the oil degradation abilities of the resuscitated bacterial cells were determined by infrared spectrophotometry. The results showed that when the concentration of benzene in the culture medium was 2.5% above, the growth of R. erythropolis KB1 could be effectively inhibited. After being cultured for 6 h, R. erythropolis KB1 cells entered the VBNC state. The VBNC cells could be resuscitated into the culturable state under certain conditions. The resuscitated bacterial cells showed good adaptabilities to the environments, and their oil degradation ability was not changed obviously.
2024, 42(1): 191-198.
doi: 10.13205/j.hjgc.202401025
Abstract:
China's water conservancy engineering construction has gradually shifted from flood control to water ecological environment restoration, and engineering construction always plays an important supporting role. This paper took the construction of an ecological reservoir in the water source area of Reservoir in a typical dense built-up area in Shenzhen as an example. The effect of ecological reservoir interception on the improvement of the water environment in water source areas in a megacity with water shortage was studied through the methods of monitoring and model before and after the construction of the project. The results showed that all kinds of pollutants in the water source area met the standards, and the water quality was increased by 3.6 times on average after the completion of the ecological reservoir. When the initial rainwater was 110 mm and the normal rainwater was 40 mm, rainwater collected by the ecological reservoir can be overflowed into the reservoir. The model predicted that the water quality of the reservoir area under the condition of normal rain was better than that of the initial rain condition, and the initial rain and normal rain could significantly improve the utilization of water resources and the water environment. After the construction of the ecological bank was completed, the initial rain and regular rain will increase the water environment capacity by 4.7 and 3.3 times, respectively. This study provides a scientific basis for the research on construction of water source areas in developed cities with water-source and water-quality water shortages.
China's water conservancy engineering construction has gradually shifted from flood control to water ecological environment restoration, and engineering construction always plays an important supporting role. This paper took the construction of an ecological reservoir in the water source area of Reservoir in a typical dense built-up area in Shenzhen as an example. The effect of ecological reservoir interception on the improvement of the water environment in water source areas in a megacity with water shortage was studied through the methods of monitoring and model before and after the construction of the project. The results showed that all kinds of pollutants in the water source area met the standards, and the water quality was increased by 3.6 times on average after the completion of the ecological reservoir. When the initial rainwater was 110 mm and the normal rainwater was 40 mm, rainwater collected by the ecological reservoir can be overflowed into the reservoir. The model predicted that the water quality of the reservoir area under the condition of normal rain was better than that of the initial rain condition, and the initial rain and normal rain could significantly improve the utilization of water resources and the water environment. After the construction of the ecological bank was completed, the initial rain and regular rain will increase the water environment capacity by 4.7 and 3.3 times, respectively. This study provides a scientific basis for the research on construction of water source areas in developed cities with water-source and water-quality water shortages.
2024, 42(1): 199-205.
doi: 10.13205/j.hjgc.202401026
Abstract:
Since the traditional groundwater risk assessment of contaminated sites ignored the risk of pollution spreading risk, a groundwater contaminated site and its surroundings in Hunan were selected as the research area for groundwater pollution dynamic risk assessment and trend prediction. A combination of quantitative and qualitative methods was used to establish a dynamic assessment method based on numerical simulation and risk screening through index screening and determination. The simulation prediction shows that the pollutants in the soil and groundwater of the site gradually diffuse downstream over time. The concentration of Cr(Ⅵ) in groundwater reaches a maximum of 1239.5 mg/L on the 38th day. Pollutants migrate to the river on the 585 day, and the groundwater pollution plume reaches its maximum on the 917th day. The total groundwater pollution risk scores of the site calculated by the two methods are 76.2 and 72.4, both belong to high risks, indicating that qualitative analysis of migration in the vadose zone and the water-saturated zone may tend to be conservative compared to quantitative analysis. The dynamic risk assessment results show that the site is always at high-risk throughout its lifetime, and the groundwater pollution risk first rises and then declines, reaching the highest risk of 95.2 points from the 500th day to the 700th day. It is suggested that groundwater risk control or restoration should be carried out to avoid greater risk.
Since the traditional groundwater risk assessment of contaminated sites ignored the risk of pollution spreading risk, a groundwater contaminated site and its surroundings in Hunan were selected as the research area for groundwater pollution dynamic risk assessment and trend prediction. A combination of quantitative and qualitative methods was used to establish a dynamic assessment method based on numerical simulation and risk screening through index screening and determination. The simulation prediction shows that the pollutants in the soil and groundwater of the site gradually diffuse downstream over time. The concentration of Cr(Ⅵ) in groundwater reaches a maximum of 1239.5 mg/L on the 38th day. Pollutants migrate to the river on the 585 day, and the groundwater pollution plume reaches its maximum on the 917th day. The total groundwater pollution risk scores of the site calculated by the two methods are 76.2 and 72.4, both belong to high risks, indicating that qualitative analysis of migration in the vadose zone and the water-saturated zone may tend to be conservative compared to quantitative analysis. The dynamic risk assessment results show that the site is always at high-risk throughout its lifetime, and the groundwater pollution risk first rises and then declines, reaching the highest risk of 95.2 points from the 500th day to the 700th day. It is suggested that groundwater risk control or restoration should be carried out to avoid greater risk.
2024, 42(1): 206-214.
doi: 10.13205/j.hjgc.202401027
Abstract:
Industrial activities of cities discharge large amounts of CO2 and pollutants. They are important sources of environmental pollution. Existing studies on the synergistic control of pollutants and CO2 emissions mostly focus on the national or provincial scale, as well as in a single environmental medium. It is necessary to investigate the synergistic nature of pollutants and CO2 emissions at the urban scale and across environmental media. This study analyzed the synergy degree between industrial CO2 emissions and the emissions of four pollutants to different environmental media(namely SO2, NOx, COD, and NH3-N) in 178 Chinese cities from 2013 to 2019. Moreover, the socioeconomic factors influencing the synergy degree were revealed.Resultsshowed that the annual mean synergy degrees of industrial CO2 and four pollutants emissions showed an “N”-shaped trend. Nearly 40% of the cities realized the synergistic control of industrial pollutants and CO2 emissions. Around 50% of the cities realized only industrial pollutants reduction. Unfortunately, about 10% of the cities have increased industrial CO2 and pollutant emissions simultaneously. Generally, strengthening government policies is a key factor influencing the industrial synergy degree. However, there is a spatial heterogeneity in the key factors influencing the synergy degree of eastern, central, and western cities. In addition, encouraging innovation and attracting talent are key factors in promoting synergistic control of pollutants and CO2 emissions in old industrial cities.
Industrial activities of cities discharge large amounts of CO2 and pollutants. They are important sources of environmental pollution. Existing studies on the synergistic control of pollutants and CO2 emissions mostly focus on the national or provincial scale, as well as in a single environmental medium. It is necessary to investigate the synergistic nature of pollutants and CO2 emissions at the urban scale and across environmental media. This study analyzed the synergy degree between industrial CO2 emissions and the emissions of four pollutants to different environmental media(namely SO2, NOx, COD, and NH3-N) in 178 Chinese cities from 2013 to 2019. Moreover, the socioeconomic factors influencing the synergy degree were revealed.Resultsshowed that the annual mean synergy degrees of industrial CO2 and four pollutants emissions showed an “N”-shaped trend. Nearly 40% of the cities realized the synergistic control of industrial pollutants and CO2 emissions. Around 50% of the cities realized only industrial pollutants reduction. Unfortunately, about 10% of the cities have increased industrial CO2 and pollutant emissions simultaneously. Generally, strengthening government policies is a key factor influencing the industrial synergy degree. However, there is a spatial heterogeneity in the key factors influencing the synergy degree of eastern, central, and western cities. In addition, encouraging innovation and attracting talent are key factors in promoting synergistic control of pollutants and CO2 emissions in old industrial cities.
2024, 42(1): 215-222.
doi: 10.13205/j.hjgc.202401028
Abstract:
In order to promote the in-depth development of CO2 conversion and utilization technology and facilitate the smooth implementation of the "dual carbon" policy, this paper has conducted a series of experimental studies on CO2 hydrogenation to methane based on the modulation of perovskite composite catalysts through basic research. Through comparison, the influence of catalyst composition factors on catalytic performance was investigated. Through a single factor variable experiment, the relationship between operational factors and catalytic performance was investigated in detail. The microstructure of the catalyst was analyzed and characterized in detail using analytical methods such as XRD, BET, SEM, CO2-TPD, XPS. The impact of catalyst physicochemical properties on catalytic activity was analyzed, and the positive role of doping Mg in perovskite type catalysts in regulating CH4 selectivity was clarified. The results show that La0.9Mg0.1Co0.5Ni0.5O3 catalyst has excellent catalytic performance at atmospheric pressure, and can achieve nearly 100% CH4 selectivity in the temperature range of 350 ℃ to 500 ℃. Through characterization methods, it has been proven that the doping of Mg can provide more CO2 adsorption sites, which plays an important auxiliary role in improving catalytic performance.
In order to promote the in-depth development of CO2 conversion and utilization technology and facilitate the smooth implementation of the "dual carbon" policy, this paper has conducted a series of experimental studies on CO2 hydrogenation to methane based on the modulation of perovskite composite catalysts through basic research. Through comparison, the influence of catalyst composition factors on catalytic performance was investigated. Through a single factor variable experiment, the relationship between operational factors and catalytic performance was investigated in detail. The microstructure of the catalyst was analyzed and characterized in detail using analytical methods such as XRD, BET, SEM, CO2-TPD, XPS. The impact of catalyst physicochemical properties on catalytic activity was analyzed, and the positive role of doping Mg in perovskite type catalysts in regulating CH4 selectivity was clarified. The results show that La0.9Mg0.1Co0.5Ni0.5O3 catalyst has excellent catalytic performance at atmospheric pressure, and can achieve nearly 100% CH4 selectivity in the temperature range of 350 ℃ to 500 ℃. Through characterization methods, it has been proven that the doping of Mg can provide more CO2 adsorption sites, which plays an important auxiliary role in improving catalytic performance.
2024, 42(1): 223-234.
doi: 10.13205/j.hjgc.202401029
Abstract:
Accurate prediction of river water quality change is an important basis for watershed water environment management. Currently, training of the commonly used data-driven deep learning model relies on large amounts of monitoring data. However, many rivers lack monitoring data so they can't meet the accuracy requirements of water quality prediction. In this study, we have developed an approach of selecting transfer conditions based on the XGBoost model. Water quality data(temperature, pH, dissolved oxygen, total nitrogen) from automatic monitoring stations across the major river in China are used for the establishment of long and short-term memory neural network(LSTM) models. The prediction ability of the LSTM model was improved by optimizing transfer learning conditions. The results showed that: 1) the prediction accuracy of the models trained by different source domains and transfer modes was quite different; 2) when the optimal transfer conditions were selected based on the XGBoost model, the prediction error(RMSE) of the transfer model was reduced by 9.6% to 28.9%, indicating that the prediction accuracy of selected LSTM model was significantly improved. 3) selecting appropriate transfer mode, using source domain data with similar properties, and increasing the amount of training data can improve the prediction accuracy of the transfer model. The modeling approach proposed in this paper can be directly applied to the prediction of river water quality with little monitoring data, which can support watershed water environment management.
Accurate prediction of river water quality change is an important basis for watershed water environment management. Currently, training of the commonly used data-driven deep learning model relies on large amounts of monitoring data. However, many rivers lack monitoring data so they can't meet the accuracy requirements of water quality prediction. In this study, we have developed an approach of selecting transfer conditions based on the XGBoost model. Water quality data(temperature, pH, dissolved oxygen, total nitrogen) from automatic monitoring stations across the major river in China are used for the establishment of long and short-term memory neural network(LSTM) models. The prediction ability of the LSTM model was improved by optimizing transfer learning conditions. The results showed that: 1) the prediction accuracy of the models trained by different source domains and transfer modes was quite different; 2) when the optimal transfer conditions were selected based on the XGBoost model, the prediction error(RMSE) of the transfer model was reduced by 9.6% to 28.9%, indicating that the prediction accuracy of selected LSTM model was significantly improved. 3) selecting appropriate transfer mode, using source domain data with similar properties, and increasing the amount of training data can improve the prediction accuracy of the transfer model. The modeling approach proposed in this paper can be directly applied to the prediction of river water quality with little monitoring data, which can support watershed water environment management.
2024, 42(1): 235-242.
doi: 10.13205/j.hjgc.202401030
Abstract:
Heavy metal contamination of shellfish has become an urgent problem of marine food safety, among which cadmium is one of the important contamination sources. The consumption of mussels contaminated with heavy metal cadmium is a serious health hazard. A non-destructive and rapid detection method for mussels contaminated with cadmium based on near-infrared reflectance spectroscopy was researched in this study. By collecting spectral data of normal and cadmium-contaminated mussels in the range of 950~1700 nm, a detection model based on the least squares projection twin support vector machine(LSPTSVM) was constructed. The parameters of the model and the number of orthogonal projection axes were optimized to obtain the best detection performance. The accuracy of the proposed LSPTSVM model achieved 99.50% for detecting cadmium-contaminated mussels, which was superior to other twin support vector machine models. The LSPTSVM model was suitable for the datasets with small samples. In the case that it was difficult to obtain many cadmium-contaminated training samples, the LSPTSVM model had better robustness than other models. The results showed that near-infrared spectroscopy combined with the LSPTSVM model can realize the detection of cadmium-contaminated mussels, which provides a new method for quality evaluation and safety detection of shellfish.
Heavy metal contamination of shellfish has become an urgent problem of marine food safety, among which cadmium is one of the important contamination sources. The consumption of mussels contaminated with heavy metal cadmium is a serious health hazard. A non-destructive and rapid detection method for mussels contaminated with cadmium based on near-infrared reflectance spectroscopy was researched in this study. By collecting spectral data of normal and cadmium-contaminated mussels in the range of 950~1700 nm, a detection model based on the least squares projection twin support vector machine(LSPTSVM) was constructed. The parameters of the model and the number of orthogonal projection axes were optimized to obtain the best detection performance. The accuracy of the proposed LSPTSVM model achieved 99.50% for detecting cadmium-contaminated mussels, which was superior to other twin support vector machine models. The LSPTSVM model was suitable for the datasets with small samples. In the case that it was difficult to obtain many cadmium-contaminated training samples, the LSPTSVM model had better robustness than other models. The results showed that near-infrared spectroscopy combined with the LSPTSVM model can realize the detection of cadmium-contaminated mussels, which provides a new method for quality evaluation and safety detection of shellfish.
2024, 42(1): 243-252.
doi: 10.13205/j.hjgc.202401031
Abstract:
In recent years, coastal eutrophication and the resulting red tide occurrences have emerged as pressing environmental concerns, posing significant challenges to the sustainable development of Shenzhen, a key city in the China Great Bay Area. Addressing this issue effectively hinges upon a comprehensive understanding of the spatiotemporal dynamics of water quality and red tide outbreaks in Shenzhen's coastal regions. This study utilized the data from the Moderate Resolution Imaging Spectroradiometer(MODIS) to establish models for remote sensing inversion of water quality parameters and automated extraction of red tide occurrences. It has unveiled, for the first time, the spatiotemporal patterns linking key water quality parameters in Shenzhen's coastal waters with red tide outbreaks and analyzed the primary driving factors. Our findings revealed an average annual affected area of red tide occurrence spanning approximately 300.50 km2 within Shenzhen's jurisdictional waters, occurring on average 2.38 times annually. Between 2015 and 2022, the annual growth rate of red tide outbreak coverage was approximately 6.7%. Suspended sediment and chlorophyll-a concentrations in the Pearl River Estuary and Shenzhen Bay surpassed those in Dapeng Bay and Daya Bay, exhibiting an increasing trend. Despite the high eutrophication level in the eastern part of the Pearl River Estuary, the frequency of red tide outbreaks remained relatively low, primarily influenced by estuarine suspended sediments. In contrast, regions with superior water quality, such as Dapeng Bay and Daya Bay, experienced higher red tide frequencies that exhibited an annual increasing trend, potentially linking to the variation in nitrogen-phosphorus ratios. The study underscored the imperative need to target nitrogen-phosphorus ratios in the Nan'ao, Kuichong, and Baguang areas and undertook a comprehensive assessment of non-point pollution sources in their terrestrial zones. This information can serve as baseline information crucial for continuously advancing environmental governance, restoration efforts, and management evaluations concerning Shenzhen and its surrounding maritime areas.
In recent years, coastal eutrophication and the resulting red tide occurrences have emerged as pressing environmental concerns, posing significant challenges to the sustainable development of Shenzhen, a key city in the China Great Bay Area. Addressing this issue effectively hinges upon a comprehensive understanding of the spatiotemporal dynamics of water quality and red tide outbreaks in Shenzhen's coastal regions. This study utilized the data from the Moderate Resolution Imaging Spectroradiometer(MODIS) to establish models for remote sensing inversion of water quality parameters and automated extraction of red tide occurrences. It has unveiled, for the first time, the spatiotemporal patterns linking key water quality parameters in Shenzhen's coastal waters with red tide outbreaks and analyzed the primary driving factors. Our findings revealed an average annual affected area of red tide occurrence spanning approximately 300.50 km2 within Shenzhen's jurisdictional waters, occurring on average 2.38 times annually. Between 2015 and 2022, the annual growth rate of red tide outbreak coverage was approximately 6.7%. Suspended sediment and chlorophyll-a concentrations in the Pearl River Estuary and Shenzhen Bay surpassed those in Dapeng Bay and Daya Bay, exhibiting an increasing trend. Despite the high eutrophication level in the eastern part of the Pearl River Estuary, the frequency of red tide outbreaks remained relatively low, primarily influenced by estuarine suspended sediments. In contrast, regions with superior water quality, such as Dapeng Bay and Daya Bay, experienced higher red tide frequencies that exhibited an annual increasing trend, potentially linking to the variation in nitrogen-phosphorus ratios. The study underscored the imperative need to target nitrogen-phosphorus ratios in the Nan'ao, Kuichong, and Baguang areas and undertook a comprehensive assessment of non-point pollution sources in their terrestrial zones. This information can serve as baseline information crucial for continuously advancing environmental governance, restoration efforts, and management evaluations concerning Shenzhen and its surrounding maritime areas.
2024, 42(1): 253-256.
Abstract:
