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2024 Vol. 42, No. 7
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2024, 42(7): 1-14.
doi: 10.13205/j.hjgc.202407001
Abstract:
In recent years, the extensive use of antibiotics has led to increasingly prominent problems of antibiotic contamination and resistance in the environment, posing a serious threat to ecological security. During the degradation of antibiotics, traditional single chemical or biological treatment processes have the disadvantages of high energy consumption and low efficiency, while intimately coupled photocatalysis and biodegradation (ICPB) can achieve efficient degradation and complete mineralization of antibiotics. In this review, the efficiency and influencing factors of antibiotic degradation in ICPB reactors were summarized to review the antibiotic degradation process and microbial community succession characteristics. Furthermore, the assignment characteristics and evolution mechanism of ARGs in ICPB reactors were analyzed. The results showed that the ICPB reactors have been proven to have excellent performance in degrading antibiotics, and the microbial community structure and cell physiological and metabolic functions in the reactors have been undergoing adaptive adjustments, which led to the evolution and flow of ARGs. It is recommended to strengthen the research of ARGs in the ICPB reactors to provide theoretical and technical support for the development of processes for efficient removal of antibiotics and ARGs.
In recent years, the extensive use of antibiotics has led to increasingly prominent problems of antibiotic contamination and resistance in the environment, posing a serious threat to ecological security. During the degradation of antibiotics, traditional single chemical or biological treatment processes have the disadvantages of high energy consumption and low efficiency, while intimately coupled photocatalysis and biodegradation (ICPB) can achieve efficient degradation and complete mineralization of antibiotics. In this review, the efficiency and influencing factors of antibiotic degradation in ICPB reactors were summarized to review the antibiotic degradation process and microbial community succession characteristics. Furthermore, the assignment characteristics and evolution mechanism of ARGs in ICPB reactors were analyzed. The results showed that the ICPB reactors have been proven to have excellent performance in degrading antibiotics, and the microbial community structure and cell physiological and metabolic functions in the reactors have been undergoing adaptive adjustments, which led to the evolution and flow of ARGs. It is recommended to strengthen the research of ARGs in the ICPB reactors to provide theoretical and technical support for the development of processes for efficient removal of antibiotics and ARGs.
2024, 42(7): 15-24.
doi: 10.13205/j.hjgc.202407002
Abstract:
Emerging contaminants (ECs) are a kind of environmental pollutants with characteristics of biotoxicity, environmental persistence, and bioaccumulation, which pose great risks to the ecological environment or human health, and are widely detected in the process units of wastewater treatment plants (WWTPs) in China. This review focuses on the characteristics of ECs in China’s WWTPs and the efficiency of each process to remove ECs. The results show that: compared with foreign standards for the control of new pollutants in WWTPs discharge and recycled water, China’s standards mostly focus on the control of pesticides, and lack restrictions on drugs and personal care products (PPCPs) and endocrine disruptors (EDCs); PPCPs and EDCs have been detected in many domestic and foreign WWTPs studies. The primary treatment process of WWTPs has limited removal efficiency of PPCPs and EDCs. Biological treatment can effectively remove the above two kinds of ECs, but it still needs an in-depth treatment process to achieve complete removal. On this basis, the removal processes for different types of ECs in WWTPs are proposed, and the future development of the process for removing ECs in WWTPs is prospected.
Emerging contaminants (ECs) are a kind of environmental pollutants with characteristics of biotoxicity, environmental persistence, and bioaccumulation, which pose great risks to the ecological environment or human health, and are widely detected in the process units of wastewater treatment plants (WWTPs) in China. This review focuses on the characteristics of ECs in China’s WWTPs and the efficiency of each process to remove ECs. The results show that: compared with foreign standards for the control of new pollutants in WWTPs discharge and recycled water, China’s standards mostly focus on the control of pesticides, and lack restrictions on drugs and personal care products (PPCPs) and endocrine disruptors (EDCs); PPCPs and EDCs have been detected in many domestic and foreign WWTPs studies. The primary treatment process of WWTPs has limited removal efficiency of PPCPs and EDCs. Biological treatment can effectively remove the above two kinds of ECs, but it still needs an in-depth treatment process to achieve complete removal. On this basis, the removal processes for different types of ECs in WWTPs are proposed, and the future development of the process for removing ECs in WWTPs is prospected.
2024, 42(7): 25-37.
doi: 10.13205/j.hjgc.202407003
Abstract:
Municipal reclaimed water plays a crucial role in water supplementation, significantly enhancing the self-purification capacity of water bodies and improving water environment quality. However, the prevalent presence of emerging trace pollutants (EMPs) in reclaimed water threatens the ecological security of rivers where it is reused. This article reviews the development process of reclaimed water in China, and introduces the evolution of standards and policies, as well as the requirements for reclaimed water quality. Focusing on the EMPs, occurrence characteristics and origins of typical EMPs such as pharmaceutical and personal care products (PPCPs), endocrine disrupting chemicals (EDCs), and perfluorinated compounds (PFCs) in reclaimed water are analyzed. It is proposed that EMPs achieve migration and transformation primarily through four pathways: dynamic transport, adsorption and desorption, physical-chemical migration and degradation, and biodegradation, during the process of river water replenishment. Analyzing the ecological risks of EMPs on river water bodies, provides insights and theoretical references for the ecological risk assessment of EMPs and the safe reuse of reclaimed water. In the future, the degradation behavior of EMPs in actual water bodies should be emphasized in the reuse of reclaimed water streams, and rigorous monitoring and management protocols for EMPs should also be implemented.
Municipal reclaimed water plays a crucial role in water supplementation, significantly enhancing the self-purification capacity of water bodies and improving water environment quality. However, the prevalent presence of emerging trace pollutants (EMPs) in reclaimed water threatens the ecological security of rivers where it is reused. This article reviews the development process of reclaimed water in China, and introduces the evolution of standards and policies, as well as the requirements for reclaimed water quality. Focusing on the EMPs, occurrence characteristics and origins of typical EMPs such as pharmaceutical and personal care products (PPCPs), endocrine disrupting chemicals (EDCs), and perfluorinated compounds (PFCs) in reclaimed water are analyzed. It is proposed that EMPs achieve migration and transformation primarily through four pathways: dynamic transport, adsorption and desorption, physical-chemical migration and degradation, and biodegradation, during the process of river water replenishment. Analyzing the ecological risks of EMPs on river water bodies, provides insights and theoretical references for the ecological risk assessment of EMPs and the safe reuse of reclaimed water. In the future, the degradation behavior of EMPs in actual water bodies should be emphasized in the reuse of reclaimed water streams, and rigorous monitoring and management protocols for EMPs should also be implemented.
2024, 42(7): 38-48.
doi: 10.13205/j.hjgc.202407004
Abstract:
Disinfection by-products (DBPs) are the reaction products during the disinfection process of drinking water, which are a serious threat to human health. Therefore, it is crucial to establish relevant models to predict their concentrations and achieve accurate control. This paper reviews the research progress of empirical models for DBPs prediction, briefly reviews the current common disinfection means, types of DBPs, and the corresponding relevant norms and standards, and explores the principles of DBP models based on regression and machine learning, respectively. The prediction effects of models constructed by taking these two approaches are summarized and evaluated. Among them, the principles of machine learning algorithms for three DBPs prediction models, namely, random forest algorithm, support vector machine, and artificial neural network, are focused on and analyzed. This paper puts forward the problems of the current DBPs disinfection by-products prediction model. It looks forward to its future development direction, aiming to promote the building of the prediction model with higher accuracy and applicability.
Disinfection by-products (DBPs) are the reaction products during the disinfection process of drinking water, which are a serious threat to human health. Therefore, it is crucial to establish relevant models to predict their concentrations and achieve accurate control. This paper reviews the research progress of empirical models for DBPs prediction, briefly reviews the current common disinfection means, types of DBPs, and the corresponding relevant norms and standards, and explores the principles of DBP models based on regression and machine learning, respectively. The prediction effects of models constructed by taking these two approaches are summarized and evaluated. Among them, the principles of machine learning algorithms for three DBPs prediction models, namely, random forest algorithm, support vector machine, and artificial neural network, are focused on and analyzed. This paper puts forward the problems of the current DBPs disinfection by-products prediction model. It looks forward to its future development direction, aiming to promote the building of the prediction model with higher accuracy and applicability.
2024, 42(7): 49-59.
doi: 10.13205/j.hjgc.202407005
Abstract:
Anaerobic digestion is one of the most effective and eco-friendly technologies for resource utilization and harmless disposal of organic wastes. In recent years, antibiotics have been widely misused and enriched into sludge, which inevitably has a potential impact on the anaerobic digestion system of sludge. This study comprehensively investigated the effects of different antibiotics on the efficacy of anaerobic digestion of sludge under various environmental conditions (temperature, concentration, substrate, exposure mode, coexistence, etc.). The results showed that antibiotics were generally inhibitory and a few tended to promote and restore. The reason for this discrepancy could be attributed to the variability in the effects of antibiotics on cell structure disruption (e.g., cell wall structure), metabolic pathways (e.g., enzyme activity, extracellular polymer secretion), and adaptive mechanisms (quorum sensing systems). However, the adverse effects of antibiotics in the system could be effectively reduced, and anaerobic digestion efficacy could be enhanced by adopting physical (such as hydrothermal, ultrasound, etc.), chemical (such as advanced oxidation technologies, ozone, electrochemistry, etc.), biological (such as the addition of exogenous bioenzymes, materials to accelerate electron transfer, etc.), and combined (such as alkali heat, ultrasound-ozone, etc.) pretreatment methods. Finally, prospects for the optimization of pretreatment methods and the potential impacts of antibiotic migration on ecosystems were discussed, which could provide references for enhancing the efficacy of anaerobic digestion.
Anaerobic digestion is one of the most effective and eco-friendly technologies for resource utilization and harmless disposal of organic wastes. In recent years, antibiotics have been widely misused and enriched into sludge, which inevitably has a potential impact on the anaerobic digestion system of sludge. This study comprehensively investigated the effects of different antibiotics on the efficacy of anaerobic digestion of sludge under various environmental conditions (temperature, concentration, substrate, exposure mode, coexistence, etc.). The results showed that antibiotics were generally inhibitory and a few tended to promote and restore. The reason for this discrepancy could be attributed to the variability in the effects of antibiotics on cell structure disruption (e.g., cell wall structure), metabolic pathways (e.g., enzyme activity, extracellular polymer secretion), and adaptive mechanisms (quorum sensing systems). However, the adverse effects of antibiotics in the system could be effectively reduced, and anaerobic digestion efficacy could be enhanced by adopting physical (such as hydrothermal, ultrasound, etc.), chemical (such as advanced oxidation technologies, ozone, electrochemistry, etc.), biological (such as the addition of exogenous bioenzymes, materials to accelerate electron transfer, etc.), and combined (such as alkali heat, ultrasound-ozone, etc.) pretreatment methods. Finally, prospects for the optimization of pretreatment methods and the potential impacts of antibiotic migration on ecosystems were discussed, which could provide references for enhancing the efficacy of anaerobic digestion.
2024, 42(7): 60-69.
doi: 10.13205/j.hjgc.202407006
Abstract:
To comprehend the current state of phthalate esters (PAEs) pollution in aquatic environments, an exhaustive review of pertinent scholarly literature spanning from 2000 to 2024 was conducted utilizing the Web of Science Core Collection. Employing CiteSpace software 6.2.R6(Advanced Version), an in-depth analysis was performed to delineate the aggregate publication count from both global scholars, main institutions and journals, and highly cited literature in the field of PAEs pollution in water environment. This comprehensive analysis elucidated the intellectual foundation, research focal points and emerging trends within this domain. The volume of publications in this field existed an upward trajectory, particularly after the year of 2013. Notably, China contributed the highest number of published papers (238, accounting for 49.1% of the total), showing a significant research presence. Chinese research institutions, notably the Chinese Academy of Sciences and Nanjing University, led the field in terms of publication output. Keyword analysis revealed "PAEs" as the largest node, while terms such as "ecological risk assessment", "sediment" and "exposure" gained prominence. Moreover, "degradation" emerged as the keyword with the strongest citation bursts. Research endeavors in this field mainly include investigation of PAEs contamination levels within the region, sources, degradation mechanisms, and ecological risk assessment. The future research will underscore the influence of climate factors on the spatial distribution of PAEs, elucidate environmental fate mechanisms such as mixed pollution, and scrutinize the migration and transformation of PAEs across various media, as well as the co-occurrence of PAEs with other pollutants.
To comprehend the current state of phthalate esters (PAEs) pollution in aquatic environments, an exhaustive review of pertinent scholarly literature spanning from 2000 to 2024 was conducted utilizing the Web of Science Core Collection. Employing CiteSpace software 6.2.R6(Advanced Version), an in-depth analysis was performed to delineate the aggregate publication count from both global scholars, main institutions and journals, and highly cited literature in the field of PAEs pollution in water environment. This comprehensive analysis elucidated the intellectual foundation, research focal points and emerging trends within this domain. The volume of publications in this field existed an upward trajectory, particularly after the year of 2013. Notably, China contributed the highest number of published papers (238, accounting for 49.1% of the total), showing a significant research presence. Chinese research institutions, notably the Chinese Academy of Sciences and Nanjing University, led the field in terms of publication output. Keyword analysis revealed "PAEs" as the largest node, while terms such as "ecological risk assessment", "sediment" and "exposure" gained prominence. Moreover, "degradation" emerged as the keyword with the strongest citation bursts. Research endeavors in this field mainly include investigation of PAEs contamination levels within the region, sources, degradation mechanisms, and ecological risk assessment. The future research will underscore the influence of climate factors on the spatial distribution of PAEs, elucidate environmental fate mechanisms such as mixed pollution, and scrutinize the migration and transformation of PAEs across various media, as well as the co-occurrence of PAEs with other pollutants.
2024, 42(7): 70-80.
doi: 10.13205/j.hjgc.202407007
Abstract:
Hexabromocyclododecane (HBCD) is an alicyclic additive flame retardant with high bromine content. It has been widely used in the production of polystyrene building insulation materials, textiles, electrical and electronic equipment. Because HBCD is not chemically bound to the products, it will be inevitably released from the product during production, use and disposal. HBCD has been proven to have toxic effects on the liver, thyroid and nerves of organisms, and its accumulation in organisms can cause serious harm to the human body. In recent years, the presence of HBCD has been detected in daily necessities, atmosphere, water, soil and various organisms, even in breast milk, which has potential long-term harm to humans and the environment. Food, air and dust are the main pathways for the human body to ingest HBCD. Regardless of the route of exposure, the exposure rate of toddlers is higher than that of adults, and occupational exposure to HBCD has a more serious impact on occupational personnel health. This article reviews the distribution and determination methods of HBCD in environmental media and organisms, summarizes its toxic effects on organisms, and discusses the human exposure pathways and risk assessment of HBCD. This paper also proposes that future research on HBCD should pay more attention to the exposure pathways and risks of occupational groups, and explore the potential mechanism of HBCD on the human body.
Hexabromocyclododecane (HBCD) is an alicyclic additive flame retardant with high bromine content. It has been widely used in the production of polystyrene building insulation materials, textiles, electrical and electronic equipment. Because HBCD is not chemically bound to the products, it will be inevitably released from the product during production, use and disposal. HBCD has been proven to have toxic effects on the liver, thyroid and nerves of organisms, and its accumulation in organisms can cause serious harm to the human body. In recent years, the presence of HBCD has been detected in daily necessities, atmosphere, water, soil and various organisms, even in breast milk, which has potential long-term harm to humans and the environment. Food, air and dust are the main pathways for the human body to ingest HBCD. Regardless of the route of exposure, the exposure rate of toddlers is higher than that of adults, and occupational exposure to HBCD has a more serious impact on occupational personnel health. This article reviews the distribution and determination methods of HBCD in environmental media and organisms, summarizes its toxic effects on organisms, and discusses the human exposure pathways and risk assessment of HBCD. This paper also proposes that future research on HBCD should pay more attention to the exposure pathways and risks of occupational groups, and explore the potential mechanism of HBCD on the human body.
2024, 42(7): 81-87.
doi: 10.13205/j.hjgc.202407008
Abstract:
To develop an assessment system for evaluating the ranking of the quantitative detection list from the nontarget screening of emerging pollutants in the environmental samples, specific indicators were determined by Delphi method, and the weight of each indicator was calculated by analytic hierarchy process (AHP), and the evaluation index was quantified by five-point score system. This assessment system integrated three modules, i.e., the target, the criterion, and the index. From the perspective of nontarget screening, investigation of chemical substances, attention, ecological and environmental hazards, quantitative detection methods, etc., 15 evaluation criteria were identified and summarized into five groups, including results of nontarget screening, use of chemical substances, level of concern, ecological and environmental risks, feasibility of quantitative detection methods. The evaluation index was quantified and the weight of each index was assigned to assess the ranking of the quantitative detection list from the nontarget screening of emerging pollutants in the environmental samples. This system was then applied to a batch of environmental samples collected from South China. The top 30 emerging pollutants included 11 pharmaceutical and personal care products (PPCPs), 8 endocrine-disrupting chemicals (EDCs), 7 pesticides, and 4 per- and polyfluoroalkyl substances (PFASs).
To develop an assessment system for evaluating the ranking of the quantitative detection list from the nontarget screening of emerging pollutants in the environmental samples, specific indicators were determined by Delphi method, and the weight of each indicator was calculated by analytic hierarchy process (AHP), and the evaluation index was quantified by five-point score system. This assessment system integrated three modules, i.e., the target, the criterion, and the index. From the perspective of nontarget screening, investigation of chemical substances, attention, ecological and environmental hazards, quantitative detection methods, etc., 15 evaluation criteria were identified and summarized into five groups, including results of nontarget screening, use of chemical substances, level of concern, ecological and environmental risks, feasibility of quantitative detection methods. The evaluation index was quantified and the weight of each index was assigned to assess the ranking of the quantitative detection list from the nontarget screening of emerging pollutants in the environmental samples. This system was then applied to a batch of environmental samples collected from South China. The top 30 emerging pollutants included 11 pharmaceutical and personal care products (PPCPs), 8 endocrine-disrupting chemicals (EDCs), 7 pesticides, and 4 per- and polyfluoroalkyl substances (PFASs).
2024, 42(7): 88-97.
doi: 10.13205/j.hjgc.202407009
Abstract:
This study evaluated the degradation efficiency of three typical microplastics (PHA (polyhydroxyalkanoate), PLA (polylactic acid), and PVC (polyvinyl chloride)) under different aerobic and anaerobic environments in ambient temperatures. The experimental results of scanning electron microscope (SEM), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), average mass, and microbial activity ratio analysis showed that PHA exhibited similar degradation rates in both aerobic and anaerobic environments, approximately 25.72 mg C/d. The surface of PHA microplastic exhibited prominent grooves and cracks, along with decreased ester group abundance, crystallinity, and average mass. On the other hand, PLA and PVC practically did not degrade due to their intrinsic structural stability and great crystallinity. Calculations of the carbon balance when PHA was degraded showed that the carbon was predominantly broken down into CH3COOH, CH4, and carbon in biomass. The proportions of these three products in aerobic and anaerobic environments differed significantly, namely 5.23% vs. 0.27%, 4.28% vs. 12.24%, and 87.05% vs. 82.50%, respectively. This may be due to different microbial numbers and critical enzyme activity involved in PHA breakdown between the aerobic and anaerobic environments. This study investigated the effects of aerobic and anaerobic settings on degradation rates and product variations of microplastics in detail, which may help formulate important theoretical guidelines for determining the environmental risk of microplastics.
This study evaluated the degradation efficiency of three typical microplastics (PHA (polyhydroxyalkanoate), PLA (polylactic acid), and PVC (polyvinyl chloride)) under different aerobic and anaerobic environments in ambient temperatures. The experimental results of scanning electron microscope (SEM), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), average mass, and microbial activity ratio analysis showed that PHA exhibited similar degradation rates in both aerobic and anaerobic environments, approximately 25.72 mg C/d. The surface of PHA microplastic exhibited prominent grooves and cracks, along with decreased ester group abundance, crystallinity, and average mass. On the other hand, PLA and PVC practically did not degrade due to their intrinsic structural stability and great crystallinity. Calculations of the carbon balance when PHA was degraded showed that the carbon was predominantly broken down into CH3COOH, CH4, and carbon in biomass. The proportions of these three products in aerobic and anaerobic environments differed significantly, namely 5.23% vs. 0.27%, 4.28% vs. 12.24%, and 87.05% vs. 82.50%, respectively. This may be due to different microbial numbers and critical enzyme activity involved in PHA breakdown between the aerobic and anaerobic environments. This study investigated the effects of aerobic and anaerobic settings on degradation rates and product variations of microplastics in detail, which may help formulate important theoretical guidelines for determining the environmental risk of microplastics.
2024, 42(7): 98-105.
doi: 10.13205/j.hjgc.202407010
Abstract:
To investigate the effect of soil colloids on the migration of nanoplastics under different hydrochemical conditions, Polystyrene nanoplastics (PSNPs) with a particle size of 100 nm were selected, and soil colloids were extracted by siphon method. The mechanism of PSNPs migration in saturated porous media was revealed by zeta potential and DLVO theory. The results showed that the migration of PSNPs was influenced by the pH and the ionic strength (IS). The mobility of PSNP increased with the increase of pH and decreased with the increase of IS. Variations in pH and IS altered the surface charges of both PSNPs and porous media thus affecting the interaction energy. As pH increased from 4.0 to 9.0 (10 mmol/L NaCl, bentonite colloid), the peak DLVO barrier increased from 45.11 kT to 61.89 kT, and the zeta potential was significantly reduced. The migration capacity of the PSNPs was improved, resulting in a rise in the outflow rate from 42.80% to 62.21%. Both bentonite colloids and illite colloids accelerated the migration of PSNPs in saturated porous media, whereas the effect of bentonite colloids on the mobility of PSNPs was more significant. The results provide valuable insights into the migration of PSNPs in subsurface soil and water environments, which is of great importance for the prevention of plastic pollution.
To investigate the effect of soil colloids on the migration of nanoplastics under different hydrochemical conditions, Polystyrene nanoplastics (PSNPs) with a particle size of 100 nm were selected, and soil colloids were extracted by siphon method. The mechanism of PSNPs migration in saturated porous media was revealed by zeta potential and DLVO theory. The results showed that the migration of PSNPs was influenced by the pH and the ionic strength (IS). The mobility of PSNP increased with the increase of pH and decreased with the increase of IS. Variations in pH and IS altered the surface charges of both PSNPs and porous media thus affecting the interaction energy. As pH increased from 4.0 to 9.0 (10 mmol/L NaCl, bentonite colloid), the peak DLVO barrier increased from 45.11 kT to 61.89 kT, and the zeta potential was significantly reduced. The migration capacity of the PSNPs was improved, resulting in a rise in the outflow rate from 42.80% to 62.21%. Both bentonite colloids and illite colloids accelerated the migration of PSNPs in saturated porous media, whereas the effect of bentonite colloids on the mobility of PSNPs was more significant. The results provide valuable insights into the migration of PSNPs in subsurface soil and water environments, which is of great importance for the prevention of plastic pollution.
2024, 42(7): 106-112.
doi: 10.13205/j.hjgc.202407011
Abstract:
To clarify the occurrence of microplastics in rainwater runoff, the sampling points in a university campus, a road, and a residential community were selected to collect samples of actual rainwater runoff. The density separation method was used to pretreat the rainwater samples, and the abundance, type and particle size of microplastics in the water samples were detected and analyzed, using an Agilent LDIR-8700 laser infrared imaging spectrometer. The presence of microplastics was detected in all samples. The abundance of microplastics was related to the number of dry days before the rainfall event, and increased with the number of dry days. The types of microplastics were related to the social life functions of the sampling sites. The particle sizes of microplastics were divided into five intervals: 0 to 30 μm, 30 to 50 μm, 50 to 100 μm, 100 to 200 μm, and 200 μm above. The particle sizes of microplastics detected at the three sampling sites were mainly in the range of 0 to 50 μm, indicating that large-size plastics would be continuously broken to form small-size microplastics by the influence of natural external forces. The results can provide data support for the detection methods of microplastics in rainwater and the sources of microplastics in water environment.
To clarify the occurrence of microplastics in rainwater runoff, the sampling points in a university campus, a road, and a residential community were selected to collect samples of actual rainwater runoff. The density separation method was used to pretreat the rainwater samples, and the abundance, type and particle size of microplastics in the water samples were detected and analyzed, using an Agilent LDIR-8700 laser infrared imaging spectrometer. The presence of microplastics was detected in all samples. The abundance of microplastics was related to the number of dry days before the rainfall event, and increased with the number of dry days. The types of microplastics were related to the social life functions of the sampling sites. The particle sizes of microplastics were divided into five intervals: 0 to 30 μm, 30 to 50 μm, 50 to 100 μm, 100 to 200 μm, and 200 μm above. The particle sizes of microplastics detected at the three sampling sites were mainly in the range of 0 to 50 μm, indicating that large-size plastics would be continuously broken to form small-size microplastics by the influence of natural external forces. The results can provide data support for the detection methods of microplastics in rainwater and the sources of microplastics in water environment.
2024, 42(7): 113-119.
doi: 10.13205/j.hjgc.202407012
Abstract:
Organic pollution is still prevalent in Dianchi Lake. A comprehensive understanding of the characteristics and sources of chemical oxygen demand (COD) would contribute to the precise management and pollution prevention. The present work employed three-dimensional fluorescence spectroscopy to analyze the organic matter characteristics in Dianchi Lake and utilized mass balance calculations to assess the annual input and output of organic pollution in 2020. The results revealed that the COD concentrations were relatively higher in the eastern and western regions of Waihai, and the organic matter of the lake exhibited autogenous characteristics. The total input of COD throughout the year was estimated to be approximately 43648 tons. Urban non-point source pollution and carbon fixation by microalgae were the main inputs and accounted for 34.6% and 31.4% of the total input volume, respectively. Furthermore, 18.9% of the total input accumulated within the lake. To mitigate organic pollution in Dianchi Lake, measures such as strengthening urban runoff control, microalgal harvesting, and sediment dredging were necessary. These findings provided theoretical support for the management of organic pollution in Dianchi Lake.
Organic pollution is still prevalent in Dianchi Lake. A comprehensive understanding of the characteristics and sources of chemical oxygen demand (COD) would contribute to the precise management and pollution prevention. The present work employed three-dimensional fluorescence spectroscopy to analyze the organic matter characteristics in Dianchi Lake and utilized mass balance calculations to assess the annual input and output of organic pollution in 2020. The results revealed that the COD concentrations were relatively higher in the eastern and western regions of Waihai, and the organic matter of the lake exhibited autogenous characteristics. The total input of COD throughout the year was estimated to be approximately 43648 tons. Urban non-point source pollution and carbon fixation by microalgae were the main inputs and accounted for 34.6% and 31.4% of the total input volume, respectively. Furthermore, 18.9% of the total input accumulated within the lake. To mitigate organic pollution in Dianchi Lake, measures such as strengthening urban runoff control, microalgal harvesting, and sediment dredging were necessary. These findings provided theoretical support for the management of organic pollution in Dianchi Lake.
2024, 42(7): 120-128.
doi: 10.13205/j.hjgc.202407013
Abstract:
To improve the purification capacity of recycled aggregates from construction and demolition waste for actual micro-polluted water, a mixture of recycled brick aggregate (RBA) and recycled concrete aggregate (RCA) in two proportions was used as substrates to construct two vertical flow constructed wetland (VFCW) systems, namely CW1 (80% RBA+20% RCA) and CW2 (50% RBA+50% RCA). A control group with natural aggregates (zeolite, lava rock, limestone) as substrates was set up. The results showed that the TP removal efficiencies during the stable operation period of CW1 and CW2 were 57.5% and 42.7%, respectively, which were 38.9% and 24.1% higher compared to the control group. The NH3-N, TN, and COD removal effect of CW2 with an increased proportion of RCA was close to that of the system with natural aggregates, with removal efficiencies of 70.2%, 16.9%, and 63.5%, respectively, achieving the effect of treating pollution with waste materials. The calculation of the Nemerow pollution index further demonstrated that increasing the proportion of RCA was conducive to improving the comprehensive pollution control efficiency of the systems with recycled aggregates, which was better than the systems with traditional natural aggregates. The environmental risk assessment indicated that the environmental risk level of effluent each pollutant in the recycled aggregate systems during the stable operation phase was at a desirable level, with a low impact on the receiving water. The economic analysis showed that the CW2 had the lowest cost and significant benefits. The VFCWs using a mixture of 50% RBA and 50% RCA as the substrate was successfully applied in the Wenyu River Wetland Park in Beijing. When the influent water quality exceeded the limit of the Class Ⅳ of Environmental Quality Standards for Surface Water (GB 3838—2002), the effluent NH3-N, TP, and COD of each outlet point all met the Class Ⅲ water quality standard.
To improve the purification capacity of recycled aggregates from construction and demolition waste for actual micro-polluted water, a mixture of recycled brick aggregate (RBA) and recycled concrete aggregate (RCA) in two proportions was used as substrates to construct two vertical flow constructed wetland (VFCW) systems, namely CW1 (80% RBA+20% RCA) and CW2 (50% RBA+50% RCA). A control group with natural aggregates (zeolite, lava rock, limestone) as substrates was set up. The results showed that the TP removal efficiencies during the stable operation period of CW1 and CW2 were 57.5% and 42.7%, respectively, which were 38.9% and 24.1% higher compared to the control group. The NH3-N, TN, and COD removal effect of CW2 with an increased proportion of RCA was close to that of the system with natural aggregates, with removal efficiencies of 70.2%, 16.9%, and 63.5%, respectively, achieving the effect of treating pollution with waste materials. The calculation of the Nemerow pollution index further demonstrated that increasing the proportion of RCA was conducive to improving the comprehensive pollution control efficiency of the systems with recycled aggregates, which was better than the systems with traditional natural aggregates. The environmental risk assessment indicated that the environmental risk level of effluent each pollutant in the recycled aggregate systems during the stable operation phase was at a desirable level, with a low impact on the receiving water. The economic analysis showed that the CW2 had the lowest cost and significant benefits. The VFCWs using a mixture of 50% RBA and 50% RCA as the substrate was successfully applied in the Wenyu River Wetland Park in Beijing. When the influent water quality exceeded the limit of the Class Ⅳ of Environmental Quality Standards for Surface Water (GB 3838—2002), the effluent NH3-N, TP, and COD of each outlet point all met the Class Ⅲ water quality standard.
2024, 42(7): 129-134.
doi: 10.13205/j.hjgc.202407014
Abstract:
To determine the influence of vertical barriers on the hydrodynamic control of contaminated groundwater and guide the design and construction of hydrodynamic interception technology, a hydrodynamic interception technology test device was established, and tests were carried out under different working conditions. Combined with the simulation results of GMS, it was found that the existence of an upstream open vertical barrier could form a large range of pollutant capture areas near the downstream pollution source, thus delaying the diffusion of pollutants and reducing the peak concentration of pollutants at the downstream monitoring point. The longer the arc length of the upstream open vertical barrier, the better the interception effect. The interception effect of the upstream pumping scheme was directly related to the pumped flow. The higher the pumped flow, the larger the range of the captured area formed in the middle reach, the slower the diffusion of pollutants, and the lower the peak concentration. The combination of vertical barriers and upstream pumping wells could very effectively reduce the pumping flow necessary to control the diffusion of pollutants, thus greatly reducing the implementation cost of the upstream pumping scheme.
To determine the influence of vertical barriers on the hydrodynamic control of contaminated groundwater and guide the design and construction of hydrodynamic interception technology, a hydrodynamic interception technology test device was established, and tests were carried out under different working conditions. Combined with the simulation results of GMS, it was found that the existence of an upstream open vertical barrier could form a large range of pollutant capture areas near the downstream pollution source, thus delaying the diffusion of pollutants and reducing the peak concentration of pollutants at the downstream monitoring point. The longer the arc length of the upstream open vertical barrier, the better the interception effect. The interception effect of the upstream pumping scheme was directly related to the pumped flow. The higher the pumped flow, the larger the range of the captured area formed in the middle reach, the slower the diffusion of pollutants, and the lower the peak concentration. The combination of vertical barriers and upstream pumping wells could very effectively reduce the pumping flow necessary to control the diffusion of pollutants, thus greatly reducing the implementation cost of the upstream pumping scheme.
2024, 42(7): 135-143.
doi: 10.13205/j.hjgc.202407015
Abstract:
To realize the efficient nitrogen removal of aerobic granular sludge (AGS), this study set an anaerobic section at the front end of the AGS system to form an anaerobic/aerobic (A/O) operation mode, to enhance the denitrification of the AGS system. At the same time, the changes in sludge characteristics and microbial community structure of AGS during the whole experiment were studied. The results showed that AGS was composed of filamentous bacteria as the skeleton, and the activated sludge continuously adhered to the skeleton under the action of hydraulic shear force to form AGS. During the process, the protein content in the extracellular polymeric substance (EPS) increased significantly, and the Zeta potential value of the sludge surface decreased, which improved the coagulation performance between the sludge and ensured the formation and stable operation of AGS. In the sludge granulation stage, the relative abundance of hydrophobic and EPS-secreting bacteria, such as unclassified_f__Sphingomonadaceae and unclassified_o__Saccharimonadales increased, which promoted sludge granulation. The intervention of A/O operation mode increased the relative abundance of nitrogen-related bacteria in the AGS system and enhanced the nitrogen removal performance of the AGS system. On the 110th day, the interventional AGS system in the low-temperature environment still maintained stable operation, and the final TN removal rate increased to 78.2%. The main reason was attributed to the increase in the relative abundance of Zoogloea (4.6%→8.2%), Thauera (2.0%→2.3%), Rhodobacter (2.3%→2.7%), norank_f__Actinomycetaceae (1.8%→3.7%), Pseudoxanthomonas (2.2%→4.5%), etc.
To realize the efficient nitrogen removal of aerobic granular sludge (AGS), this study set an anaerobic section at the front end of the AGS system to form an anaerobic/aerobic (A/O) operation mode, to enhance the denitrification of the AGS system. At the same time, the changes in sludge characteristics and microbial community structure of AGS during the whole experiment were studied. The results showed that AGS was composed of filamentous bacteria as the skeleton, and the activated sludge continuously adhered to the skeleton under the action of hydraulic shear force to form AGS. During the process, the protein content in the extracellular polymeric substance (EPS) increased significantly, and the Zeta potential value of the sludge surface decreased, which improved the coagulation performance between the sludge and ensured the formation and stable operation of AGS. In the sludge granulation stage, the relative abundance of hydrophobic and EPS-secreting bacteria, such as unclassified_f__Sphingomonadaceae and unclassified_o__Saccharimonadales increased, which promoted sludge granulation. The intervention of A/O operation mode increased the relative abundance of nitrogen-related bacteria in the AGS system and enhanced the nitrogen removal performance of the AGS system. On the 110th day, the interventional AGS system in the low-temperature environment still maintained stable operation, and the final TN removal rate increased to 78.2%. The main reason was attributed to the increase in the relative abundance of Zoogloea (4.6%→8.2%), Thauera (2.0%→2.3%), Rhodobacter (2.3%→2.7%), norank_f__Actinomycetaceae (1.8%→3.7%), Pseudoxanthomonas (2.2%→4.5%), etc.
2024, 42(7): 144-152.
doi: 10.13205/j.hjgc.202407016
Abstract:
The Chengdu Section of the Tuojiang River Basin is densely populated and has prominent river pollution problems. In recent years, the pollution problem has received attention and the situation has been significantly improved. Based on three field investigations from 2022 to 2023, the current pollution status of the overlying water and sediments in the Chengdu Section of the Tuojiang River Basin was evaluated using the Nemerow integrated pollution index method based on field investigations. The correlation between overlying water and sediment was sought to provide a basis for the management of water ecological protection in the Chengdu Section of the Tuojiang River Basin and the Yangtze River. The research results showed that: the most important exceedance factors of the water body were total nitrogen and chemical oxygen demand. The Nemerow comprehensive pollution assessment indicated that the water body was in a moderate to heavy pollution level. The main pollutants of the sediment were total nitrogen, total phosphorus, and heavy metal chromium. The Nemerow comprehensive pollution assessment indicated that the sediment was at light to moderate pollution level. There was a strong correlation between water and sediment, among which the total phosphorus of water was significantly positively correlated with inorganic phosphorus of sediment, and the correlation coefficient was 0.506. Sediment pollutants have a great influence on the water body, so the control of river pollution from external sources should also increase the management of river pollution from internal sources.
The Chengdu Section of the Tuojiang River Basin is densely populated and has prominent river pollution problems. In recent years, the pollution problem has received attention and the situation has been significantly improved. Based on three field investigations from 2022 to 2023, the current pollution status of the overlying water and sediments in the Chengdu Section of the Tuojiang River Basin was evaluated using the Nemerow integrated pollution index method based on field investigations. The correlation between overlying water and sediment was sought to provide a basis for the management of water ecological protection in the Chengdu Section of the Tuojiang River Basin and the Yangtze River. The research results showed that: the most important exceedance factors of the water body were total nitrogen and chemical oxygen demand. The Nemerow comprehensive pollution assessment indicated that the water body was in a moderate to heavy pollution level. The main pollutants of the sediment were total nitrogen, total phosphorus, and heavy metal chromium. The Nemerow comprehensive pollution assessment indicated that the sediment was at light to moderate pollution level. There was a strong correlation between water and sediment, among which the total phosphorus of water was significantly positively correlated with inorganic phosphorus of sediment, and the correlation coefficient was 0.506. Sediment pollutants have a great influence on the water body, so the control of river pollution from external sources should also increase the management of river pollution from internal sources.
2024, 42(7): 153-161.
doi: 10.13205/j.hjgc.202407017
Abstract:
Jincheng is an important coal chemical industry base in China, and its industrial economic structure is dominated by heavy industry. In recent years, PM2.5 pollution has become prominent in Jincheng. Atmospheric PM2.5 samples were collected from three sites in Jincheng in the autumn and winter from 2018 to 2019. This study analyzed the component concentrations (ions, elements, and carbon) and secondary transformation characteristics under different conditions. Backward trajectory was used to investigate the impact of regional transport on ambient air, and a chemical mass balance model was used to analyze the source of PM2.5. The results showed that: 1) the concentration of PM2.5 in Jincheng was 86.1 μg/m3 during the sampling period. The PM2.5 concentration in the polluted period (131.1 μg/m3) was 2.3 times higher than that in the clean period (58.2 μg/m3), which maybe related to the high humidity and static stability conditions. 2) secondary inorganic ions were the main component (83.4%) of water-soluble ions in PM2.5 in Jincheng, which had a higher concentration in the polluted period (71.2 μg/m3) than clean period (24.6 μg/m3). The conversion of SO2 to SO2-4 in autumn and winter in Jincheng was mainly dominated by heterogeneous reactions, while the formation of NO-3 was influenced by both oxidation and heterogeneous hydrolysis. Compared with the clean period, the concentrations of OC and EC in polluted days increased by 88.5% and 83.0%, respectively. The backward trajectory results showed that under the influence of adverse meteorological conditions, the short-distance air mass from the southeast of Jincheng in January aggravated the pollution process, which reflected the importance of regional joint prevention and control. The results of source apportionment showed that dust source (18.4%), secondary nitrates (16.5%), coal combustion (15.9%) source, and vehicle source (12.0%) were the main source of PM2.5. Therefore, to further reduce the concentration of PM2.5 in Jincheng, it is necessary to strengthen the control of vehicle and coal combustion in autumn and winter to reduce the emissions of the primary pollutants (SO2 and NO2).
Jincheng is an important coal chemical industry base in China, and its industrial economic structure is dominated by heavy industry. In recent years, PM2.5 pollution has become prominent in Jincheng. Atmospheric PM2.5 samples were collected from three sites in Jincheng in the autumn and winter from 2018 to 2019. This study analyzed the component concentrations (ions, elements, and carbon) and secondary transformation characteristics under different conditions. Backward trajectory was used to investigate the impact of regional transport on ambient air, and a chemical mass balance model was used to analyze the source of PM2.5. The results showed that: 1) the concentration of PM2.5 in Jincheng was 86.1 μg/m3 during the sampling period. The PM2.5 concentration in the polluted period (131.1 μg/m3) was 2.3 times higher than that in the clean period (58.2 μg/m3), which maybe related to the high humidity and static stability conditions. 2) secondary inorganic ions were the main component (83.4%) of water-soluble ions in PM2.5 in Jincheng, which had a higher concentration in the polluted period (71.2 μg/m3) than clean period (24.6 μg/m3). The conversion of SO2 to SO2-4 in autumn and winter in Jincheng was mainly dominated by heterogeneous reactions, while the formation of NO-3 was influenced by both oxidation and heterogeneous hydrolysis. Compared with the clean period, the concentrations of OC and EC in polluted days increased by 88.5% and 83.0%, respectively. The backward trajectory results showed that under the influence of adverse meteorological conditions, the short-distance air mass from the southeast of Jincheng in January aggravated the pollution process, which reflected the importance of regional joint prevention and control. The results of source apportionment showed that dust source (18.4%), secondary nitrates (16.5%), coal combustion (15.9%) source, and vehicle source (12.0%) were the main source of PM2.5. Therefore, to further reduce the concentration of PM2.5 in Jincheng, it is necessary to strengthen the control of vehicle and coal combustion in autumn and winter to reduce the emissions of the primary pollutants (SO2 and NO2).
2024, 42(7): 162-170.
doi: 10.13205/j.hjgc.202407018
Abstract:
Atmospheric ammonia (NH3) has an important impact on the formation of secondary aerosols. To investigate the characteristics of atmospheric NH3 pollution in Shihezi, the atmospheric NH3 concentration was observed continuously from December 2020 to November 2021, and the magnitude level, variation characteristics, and influencing factors of atmospheric NH3 in Shihezi were analyzed, in combination with the characteristics of atmospheric NH3 emissions and the characteristics of concurrent meteorological parameters. The results show that the annual average concentration of atmospheric NH3 in Shihezi was 21.0 μg/m3, the average concentration of atmospheric NH3 in the four seasons ranged from 20.2 μg/m3 to 21.7 μg/m3, with a small seasonal fluctuation. In winter, the main source of atmospheric NH3 in Shihezi was the escape of ammonia during the industrial flue gas denitrification process, and the continuous low boundary layer height and low wind speed in winter led to the deterioration of atmospheric diffusion conditions. The unfavorable diffusion conditions were an important reason for the accumulation of atmospheric NH3 concentration in winter. Increasing the control of ammonia escape during flue gas denitrification was beneficial to reducing the atmospheric NH3 concentration in Shihezi. The diurnal variation of atmospheric NH3 concentration showed a pattern of higher during the day and lower at night in Shihezi in all seasons, with the daily variation of atmospheric NH3 concentration being highest in spring and lowest in winter. The atmospheric NH3 concentrations in spring and winter showed a single-peak pattern, with dual peaks at 12:00 and 16:00, respectively, and summer and autumn atmospheric NH3 concentrations showed a multi-peak pattern, with maximum peaks at 11:00 and 13:00, respectively. Compared with other cities in China, the daytime peak of atmospheric NH3 concentration in Shihezi appeared 1 to 3 hours later. The quantitative evaluation of the influencing factors of atmospheric NH3 concentration by the random forest algorithm showed that the influence of meteorological factors on atmospheric NH3 in the four seasons reached 63.6%, 58.8%, 73.9%, and 64.5%, respectively, and meteorological factors were the main influencing factors of atmospheric NH3 concentration.
Atmospheric ammonia (NH3) has an important impact on the formation of secondary aerosols. To investigate the characteristics of atmospheric NH3 pollution in Shihezi, the atmospheric NH3 concentration was observed continuously from December 2020 to November 2021, and the magnitude level, variation characteristics, and influencing factors of atmospheric NH3 in Shihezi were analyzed, in combination with the characteristics of atmospheric NH3 emissions and the characteristics of concurrent meteorological parameters. The results show that the annual average concentration of atmospheric NH3 in Shihezi was 21.0 μg/m3, the average concentration of atmospheric NH3 in the four seasons ranged from 20.2 μg/m3 to 21.7 μg/m3, with a small seasonal fluctuation. In winter, the main source of atmospheric NH3 in Shihezi was the escape of ammonia during the industrial flue gas denitrification process, and the continuous low boundary layer height and low wind speed in winter led to the deterioration of atmospheric diffusion conditions. The unfavorable diffusion conditions were an important reason for the accumulation of atmospheric NH3 concentration in winter. Increasing the control of ammonia escape during flue gas denitrification was beneficial to reducing the atmospheric NH3 concentration in Shihezi. The diurnal variation of atmospheric NH3 concentration showed a pattern of higher during the day and lower at night in Shihezi in all seasons, with the daily variation of atmospheric NH3 concentration being highest in spring and lowest in winter. The atmospheric NH3 concentrations in spring and winter showed a single-peak pattern, with dual peaks at 12:00 and 16:00, respectively, and summer and autumn atmospheric NH3 concentrations showed a multi-peak pattern, with maximum peaks at 11:00 and 13:00, respectively. Compared with other cities in China, the daytime peak of atmospheric NH3 concentration in Shihezi appeared 1 to 3 hours later. The quantitative evaluation of the influencing factors of atmospheric NH3 concentration by the random forest algorithm showed that the influence of meteorological factors on atmospheric NH3 in the four seasons reached 63.6%, 58.8%, 73.9%, and 64.5%, respectively, and meteorological factors were the main influencing factors of atmospheric NH3 concentration.
2024, 42(7): 171-182.
doi: 10.13205/j.hjgc.202407019
Abstract:
Based on the daily average concentration data of PM2.5 and O3 from environmental monitoring stations in Fujian Province from 2017 to 2021, the change characteristics and correlation of PM2.5 and O3 concentrations in different time scales were discussed, and the potential spatial correlation of PM2.5 and O3 pollution was explored by univariate and bivariate spatial autocorrelation analysis methods. The results showed that the annual average concentrations of PM2.5 and O3 in Fujian Province showed an overall downward trend in the past five years, and the trend of annual average concentration change was relatively synchronous. The high monthly average concentration of PM2.5 appeared in January to February, and November to December, and the low value appeared in June to August. The monthly variation showed a "U" distribution with high points at both ends and a low point in the middle. The high monthly average concentration of O3 appeared in April to May and September to October, the low value appeared in January and December, and the monthly variation showed a bimodal "M" distribution. The concentrations of PM2.5 and O3 were positively correlated from January to October, and negatively correlated from November to December. Under different concentrations of PM2.5 pollution, the change in O3 concentration was different. When the concentration of PM2.5 was less than 45 μg/m3, there was a positive correlation between PM2.5 and O3 concentration, while when the concentration of PM2.5 was more than 45 μg/m3, there was a negative correlation between them. There was a spatial positive autocorrelation between the average annual and seasonal concentrations of PM2.5 and O3, the L-L clustering area was located in the northwest, mainly distributed in Longyan, Sanming, and Nanping, and the H-H clustering area was located in the southeast, mainly distributed in Fuzhou, Putian, Xiamen and Zhangzhou. The spatial distribution of the annual and the seasonal average concentration of PM2.5 and O3 had obvious clustering and similarity.
Based on the daily average concentration data of PM2.5 and O3 from environmental monitoring stations in Fujian Province from 2017 to 2021, the change characteristics and correlation of PM2.5 and O3 concentrations in different time scales were discussed, and the potential spatial correlation of PM2.5 and O3 pollution was explored by univariate and bivariate spatial autocorrelation analysis methods. The results showed that the annual average concentrations of PM2.5 and O3 in Fujian Province showed an overall downward trend in the past five years, and the trend of annual average concentration change was relatively synchronous. The high monthly average concentration of PM2.5 appeared in January to February, and November to December, and the low value appeared in June to August. The monthly variation showed a "U" distribution with high points at both ends and a low point in the middle. The high monthly average concentration of O3 appeared in April to May and September to October, the low value appeared in January and December, and the monthly variation showed a bimodal "M" distribution. The concentrations of PM2.5 and O3 were positively correlated from January to October, and negatively correlated from November to December. Under different concentrations of PM2.5 pollution, the change in O3 concentration was different. When the concentration of PM2.5 was less than 45 μg/m3, there was a positive correlation between PM2.5 and O3 concentration, while when the concentration of PM2.5 was more than 45 μg/m3, there was a negative correlation between them. There was a spatial positive autocorrelation between the average annual and seasonal concentrations of PM2.5 and O3, the L-L clustering area was located in the northwest, mainly distributed in Longyan, Sanming, and Nanping, and the H-H clustering area was located in the southeast, mainly distributed in Fuzhou, Putian, Xiamen and Zhangzhou. The spatial distribution of the annual and the seasonal average concentration of PM2.5 and O3 had obvious clustering and similarity.
2024, 42(7): 183-189.
doi: 10.13205/j.hjgc.202407020
Abstract:
The collaborative disposal of industrial organic solid waste and increasingly strict NOx emission requirements have brought double challenges to the clean and stable operation of municipal waste incineration projects. The application effect of traditional exhaust gas recirculation technology has been affected, and it is difficult to meet the needs of the new situation, so it is urgent to develop more efficient swirling exhaust gas recirculation technology. This study analyzed the influence of applying swirling exhaust gas recirculation technology on furnace temperature control and NOx emissions of waste incinerators through numerical simulation and engineering experiments. The results showed that at under the exhaust gas recirculation ratio of 10%, the average temperature of the furnace decreased by about 20 ℃, reducing the risk of coking; swirling exhaust gas recirculation combined with SNCR technology can effectively control the NOx emission concentration below 80 mg/Nm3, reduce ammonia consumption by 35%, and reduce denitrification costs per ton of waste by 40.43%, achieving clean and stable incineration with significant economic benefits.
The collaborative disposal of industrial organic solid waste and increasingly strict NOx emission requirements have brought double challenges to the clean and stable operation of municipal waste incineration projects. The application effect of traditional exhaust gas recirculation technology has been affected, and it is difficult to meet the needs of the new situation, so it is urgent to develop more efficient swirling exhaust gas recirculation technology. This study analyzed the influence of applying swirling exhaust gas recirculation technology on furnace temperature control and NOx emissions of waste incinerators through numerical simulation and engineering experiments. The results showed that at under the exhaust gas recirculation ratio of 10%, the average temperature of the furnace decreased by about 20 ℃, reducing the risk of coking; swirling exhaust gas recirculation combined with SNCR technology can effectively control the NOx emission concentration below 80 mg/Nm3, reduce ammonia consumption by 35%, and reduce denitrification costs per ton of waste by 40.43%, achieving clean and stable incineration with significant economic benefits.
2024, 42(7): 190-199.
doi: 10.13205/j.hjgc.202407021
Abstract:
As an important index of ecosystem service function, carbon storage is the result of the comprehensive effects of human activities, hydrothermal changes, and vegetation growth. As one of the key ecological protection areas in western China, the prediction and quantitative assessment of land use and carbon storage of Qilian Mountain National Park is of great significance for the realization of the dual carbon target and the scientific division of protection areas in western China. In this study, the InVEST model was used to reveal the carbon storage effect of land use change in Qilian Mountain National Park from 2000 to 2020, and the FLUS model was coupled to predict the impact of land use change and carbon storage in the study area in 2030. The results showed as follows: 1) from 2000 to 2020, grassland and wetland in the study area continued to decrease, forest land and water area continued to increase, cultivated land and unused land increased first and then decreased, and construction land decreased first and then increased. The carbon storage in the study area was relatively high on the whole, but with the change in land use, the carbon storage showed a slowly increasing trend, and the cumulative increase of carbon storage was 9.35×107 t in 20 years. 2) The spatial distribution pattern of carbon storage in the study area was lower in the west and higher in the east. The high accumulation area was mainly distributed in the central and eastern regions with large and contiguous ecological land, while the low accumulation area was mainly distributed in the western regions with high land development intensity and ecological land fragmentation. The main factors affecting the spatial distribution pattern of carbon storage were forestland and grassland with high carbon storage. 3) In the case of natural development, carbon storage in the study area will reach 9.4×108 t in 2030, increased by 9.30% compared with 2020. The main reason for this change is the large-scale increase in forest land. The results provide a scientific basis for the strict implementation of ecological protection policies such as the Qilian Mountain ecological red line, and provide a scientific reference for further optimizing the land use structure of the Qilian Mountain National Park and slowing down the loss of regional carbon stocks.
As an important index of ecosystem service function, carbon storage is the result of the comprehensive effects of human activities, hydrothermal changes, and vegetation growth. As one of the key ecological protection areas in western China, the prediction and quantitative assessment of land use and carbon storage of Qilian Mountain National Park is of great significance for the realization of the dual carbon target and the scientific division of protection areas in western China. In this study, the InVEST model was used to reveal the carbon storage effect of land use change in Qilian Mountain National Park from 2000 to 2020, and the FLUS model was coupled to predict the impact of land use change and carbon storage in the study area in 2030. The results showed as follows: 1) from 2000 to 2020, grassland and wetland in the study area continued to decrease, forest land and water area continued to increase, cultivated land and unused land increased first and then decreased, and construction land decreased first and then increased. The carbon storage in the study area was relatively high on the whole, but with the change in land use, the carbon storage showed a slowly increasing trend, and the cumulative increase of carbon storage was 9.35×107 t in 20 years. 2) The spatial distribution pattern of carbon storage in the study area was lower in the west and higher in the east. The high accumulation area was mainly distributed in the central and eastern regions with large and contiguous ecological land, while the low accumulation area was mainly distributed in the western regions with high land development intensity and ecological land fragmentation. The main factors affecting the spatial distribution pattern of carbon storage were forestland and grassland with high carbon storage. 3) In the case of natural development, carbon storage in the study area will reach 9.4×108 t in 2030, increased by 9.30% compared with 2020. The main reason for this change is the large-scale increase in forest land. The results provide a scientific basis for the strict implementation of ecological protection policies such as the Qilian Mountain ecological red line, and provide a scientific reference for further optimizing the land use structure of the Qilian Mountain National Park and slowing down the loss of regional carbon stocks.
2024, 42(7): 200-207.
doi: 10.13205/j.hjgc.202407022
Abstract:
At present, in the process of food waste treatment, the situation that anaerobic digestion microorganisms coated by lipids often occurs. After lipids extraction, a large amount of lipids still enters the digestion system, which causes certain harm to the stability of the system. To alleviate this problem, the promoting effect of electric pretreatment on anaerobic digestion of high lipid content food waste was studied in this research. Compared with the untreated group, the methane yield of food waste (50% of lipids) treated with 0.8 V increased by 6.5% from (780.43±4.49) mL/g TVS to (831.06±13.85) mL/g TVS. The peak methane production rate increased by 20.3%, from (35.84±0.64) mL/(g TVS·d) to (43.11±0.72) mL/(g TVS·d). The time to reach the peak rate was reduced from 20 days to 14 days. The results showed that in a certain range of added lipids (0 to 50%), with the increase of lipids content, electric pretreatment demonstrated a better promoting effect on anaerobic digestion. Microscopic images showed that a large number of microorganisms were attached to the electrode surface at a voltage of 0.8 V, while no microorganisms were observed in the untreated group. According to the results of the three-dimensional fluorescence spectrum test, utilization of metabolic substrates such as humic acid was significantly improved at a voltage of 0.8 V. The promoting effect of voltage on the anaerobic digestion of high lipid content food waste can be explained from three aspects: enhancing the contact between microorganisms and electrodes, promoting the acidification and degradation of lipids, and improving the electron transfer through acetoxylation and methanation pathways.
At present, in the process of food waste treatment, the situation that anaerobic digestion microorganisms coated by lipids often occurs. After lipids extraction, a large amount of lipids still enters the digestion system, which causes certain harm to the stability of the system. To alleviate this problem, the promoting effect of electric pretreatment on anaerobic digestion of high lipid content food waste was studied in this research. Compared with the untreated group, the methane yield of food waste (50% of lipids) treated with 0.8 V increased by 6.5% from (780.43±4.49) mL/g TVS to (831.06±13.85) mL/g TVS. The peak methane production rate increased by 20.3%, from (35.84±0.64) mL/(g TVS·d) to (43.11±0.72) mL/(g TVS·d). The time to reach the peak rate was reduced from 20 days to 14 days. The results showed that in a certain range of added lipids (0 to 50%), with the increase of lipids content, electric pretreatment demonstrated a better promoting effect on anaerobic digestion. Microscopic images showed that a large number of microorganisms were attached to the electrode surface at a voltage of 0.8 V, while no microorganisms were observed in the untreated group. According to the results of the three-dimensional fluorescence spectrum test, utilization of metabolic substrates such as humic acid was significantly improved at a voltage of 0.8 V. The promoting effect of voltage on the anaerobic digestion of high lipid content food waste can be explained from three aspects: enhancing the contact between microorganisms and electrodes, promoting the acidification and degradation of lipids, and improving the electron transfer through acetoxylation and methanation pathways.
2024, 42(7): 208-216.
doi: 10.13205/j.hjgc.202407023
Abstract:
In order to quickly and efficiently solve the stability problem of steel slag, this paper studied the effects of material factors (microbial concentration, urea concentration) and treatment methods (treatment time, treatment temperature) on the stability and compressive strength of steel slag modified by Bacillus Pasteuris. The impact of the above factors on the properties of microbe-modified steel slag was analyzed using X-ray diffraction analyzer, scanning electron microscope, and other testing methods. On this basis, the modified steel slag was applied to the road base, and the 7-day unconfined compressive strength and water-soaked expansion rate of the specimen were studied. The results showed that: 1) the volume stability of steel slag could be effectively improved by using Bacillus pasteuris. When the microbial content was 60% of the mass of steel slag, the urea concentration was 2 mol/L, the treatment temperature was (20±2) ℃, and the treatment time was 72 h, the treatment effect of microbial on steel slag was the best, and the content of f-CaO in steel slag was 2.98%, which met the requirements of the code. 2) using modified steel slag to prepare road base material, when the cement content was 6%, the 7-day unconfined compressive strength of the base course of Expressway and class Ⅰ highway, the base course of class Ⅱ and below highways, and the base-bottom course of class Ⅱ and below highways are 4.1 MPa, 4.6 MPa and 5.1 MPa, respectively. Compared with the specimens before modification, they were increased by 20.6%, 9.5%, and 8.5%, respectively. The water-soaked expansion rates were 1.77%, 1.84%, and 1.92%, respectively, which all met the requirements in the code of less than 2%.
In order to quickly and efficiently solve the stability problem of steel slag, this paper studied the effects of material factors (microbial concentration, urea concentration) and treatment methods (treatment time, treatment temperature) on the stability and compressive strength of steel slag modified by Bacillus Pasteuris. The impact of the above factors on the properties of microbe-modified steel slag was analyzed using X-ray diffraction analyzer, scanning electron microscope, and other testing methods. On this basis, the modified steel slag was applied to the road base, and the 7-day unconfined compressive strength and water-soaked expansion rate of the specimen were studied. The results showed that: 1) the volume stability of steel slag could be effectively improved by using Bacillus pasteuris. When the microbial content was 60% of the mass of steel slag, the urea concentration was 2 mol/L, the treatment temperature was (20±2) ℃, and the treatment time was 72 h, the treatment effect of microbial on steel slag was the best, and the content of f-CaO in steel slag was 2.98%, which met the requirements of the code. 2) using modified steel slag to prepare road base material, when the cement content was 6%, the 7-day unconfined compressive strength of the base course of Expressway and class Ⅰ highway, the base course of class Ⅱ and below highways, and the base-bottom course of class Ⅱ and below highways are 4.1 MPa, 4.6 MPa and 5.1 MPa, respectively. Compared with the specimens before modification, they were increased by 20.6%, 9.5%, and 8.5%, respectively. The water-soaked expansion rates were 1.77%, 1.84%, and 1.92%, respectively, which all met the requirements in the code of less than 2%.
2024, 42(7): 217-224.
doi: 10.13205/j.hjgc.202407024
Abstract:
Based on the self-designed hollow auger series pyrolyzer (HASP) for waste tires in pilot scale, continuous operation experiments were carried out to analyze the stability and characteristics of products, as well as the reliability of production coupling with coal-fired units. Series pyrolysis technology and circulating spray condensation technology of pyrolysis oil were adopted to achieve stable control of pyrolysis carbon black, pyrolysis oil, and pyrolysis non-condensing gas yield in pilot pyrolysis plants. It can obtain high quality carbon black with toluene transmittance at 99%, and achieve effective separation of oils in different flash points. The non-condensing gas generated from the pyrolysis of waste tires can maintain the thermal self-sustaining operation of the plant and significantly reduce the energy input requirement during the pyrolysis process. The low flash point oil and surplus non-condensing gas were used as coupling alternative fuels for coal-fired units to reduce coal consumption and the low pollutant and carbon emissions. The experimental results proved the feasibility and reliability of the continuous, efficient, and stable operation of HASP coupled with coal-fired units, which was conducive to the popularization and application of large-scale production of waste tire pyrolysis installations.
Based on the self-designed hollow auger series pyrolyzer (HASP) for waste tires in pilot scale, continuous operation experiments were carried out to analyze the stability and characteristics of products, as well as the reliability of production coupling with coal-fired units. Series pyrolysis technology and circulating spray condensation technology of pyrolysis oil were adopted to achieve stable control of pyrolysis carbon black, pyrolysis oil, and pyrolysis non-condensing gas yield in pilot pyrolysis plants. It can obtain high quality carbon black with toluene transmittance at 99%, and achieve effective separation of oils in different flash points. The non-condensing gas generated from the pyrolysis of waste tires can maintain the thermal self-sustaining operation of the plant and significantly reduce the energy input requirement during the pyrolysis process. The low flash point oil and surplus non-condensing gas were used as coupling alternative fuels for coal-fired units to reduce coal consumption and the low pollutant and carbon emissions. The experimental results proved the feasibility and reliability of the continuous, efficient, and stable operation of HASP coupled with coal-fired units, which was conducive to the popularization and application of large-scale production of waste tire pyrolysis installations.
2024, 42(7): 225-232.
doi: 10.13205/j.hjgc.202407025
Abstract:
To promote the healthy and sustainable development of the recycled copper industry, the imported recycled copper raw materials as well as the recycled copper prepared from China’s domestic copper scrap as raw materials, were taken as the research objects, and the ReCiPe 2016 mid-point and end-point methods were used to carry out the life cycle assessment and analyze the main factors causing environmental impacts in the production process. The results show that the environmental impact of the imported recycled copper raw material resource production is relatively smaller compared with the domestic copper scrap recycling. Among the environmental impact categories, human carcinogenicity toxicity is the most significant environmental impact in the process of the imported recycled copper raw materials and domestic copper scrap recycling. Energy, transportation, and production emissions are the top three contributors to the human health impacts of imported recycled copper feedstock resourcing, accounting for 46.7%, 37.4%, and 14.2%, respectively. In the process of domestic copper scrap regeneration, energy, production emissions, and auxiliary materials contribute more to the impact on human health, accounting for 37.9%, 31.1%, and 27.1%, respectively. Based on the above analysis and combined with China’s actual situation, suggestions are put forward to mitigate the environmental impact of the recycled copper production process.
To promote the healthy and sustainable development of the recycled copper industry, the imported recycled copper raw materials as well as the recycled copper prepared from China’s domestic copper scrap as raw materials, were taken as the research objects, and the ReCiPe 2016 mid-point and end-point methods were used to carry out the life cycle assessment and analyze the main factors causing environmental impacts in the production process. The results show that the environmental impact of the imported recycled copper raw material resource production is relatively smaller compared with the domestic copper scrap recycling. Among the environmental impact categories, human carcinogenicity toxicity is the most significant environmental impact in the process of the imported recycled copper raw materials and domestic copper scrap recycling. Energy, transportation, and production emissions are the top three contributors to the human health impacts of imported recycled copper feedstock resourcing, accounting for 46.7%, 37.4%, and 14.2%, respectively. In the process of domestic copper scrap regeneration, energy, production emissions, and auxiliary materials contribute more to the impact on human health, accounting for 37.9%, 31.1%, and 27.1%, respectively. Based on the above analysis and combined with China’s actual situation, suggestions are put forward to mitigate the environmental impact of the recycled copper production process.
