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2023 Vol. 41, No. 9
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2023, 41(9): 1-9.
doi: 10.13205/j.hjgc.202309001
Abstract:
This study investigated the startup and long-term nitrogen removal efficiency, activities of functional bacteria, and microbial structure of partial denitrification coupling Anammox (PD/A) with biofilm and granular sludge. Batch tests were conducted to investigate the effect of the carbon source type and C/N(COD/NO3--N) on nitrogen removal efficiency of PD/A sludge with different sludge aggregation modes. Results showed that both biofilm and granular sludge systems could achieve efficient removal efficiency of ammonia (NH4+-N) and nitrate (NO3--N), with total nitrogen (TN) removal efficiency of 90.6% and 96.2%, respectively. The carbon source type affected PD process achieving nitrite (NO2--N) accumulation obviously. The specific reduction rate of nitrate (μNO3) in descending order was sodium acetate, glucose, ethanol and methanol, when C/N was 5.0 in the biofilm system. The specific reduction of ammonia (μNH4) in descending order was glucose, ethanol, sodium acetate and methanol, when C/N was 3.0. The activity of the Anammox process increased with the activity of PD process under a suitable C/N. It held a strong PD process when the sodium acetate was the carbon source in the granular sludge system, however, it held a weaker PD process than biofilm system with the carbon source type changed. Therefore, selecting an appropriate carbon source and C/N for different sludge aggregation systems is beneficial for maintaining the stability of PD/A process.
This study investigated the startup and long-term nitrogen removal efficiency, activities of functional bacteria, and microbial structure of partial denitrification coupling Anammox (PD/A) with biofilm and granular sludge. Batch tests were conducted to investigate the effect of the carbon source type and C/N(COD/NO3--N) on nitrogen removal efficiency of PD/A sludge with different sludge aggregation modes. Results showed that both biofilm and granular sludge systems could achieve efficient removal efficiency of ammonia (NH4+-N) and nitrate (NO3--N), with total nitrogen (TN) removal efficiency of 90.6% and 96.2%, respectively. The carbon source type affected PD process achieving nitrite (NO2--N) accumulation obviously. The specific reduction rate of nitrate (μNO3) in descending order was sodium acetate, glucose, ethanol and methanol, when C/N was 5.0 in the biofilm system. The specific reduction of ammonia (μNH4) in descending order was glucose, ethanol, sodium acetate and methanol, when C/N was 3.0. The activity of the Anammox process increased with the activity of PD process under a suitable C/N. It held a strong PD process when the sodium acetate was the carbon source in the granular sludge system, however, it held a weaker PD process than biofilm system with the carbon source type changed. Therefore, selecting an appropriate carbon source and C/N for different sludge aggregation systems is beneficial for maintaining the stability of PD/A process.
2023, 41(9): 10-17.
doi: 10.13205/j.hjgc.202309002
Abstract:
Gravity-driven membrane filtration (GDM) technology has shown significant advantages in the field of water treatment, especially in the safety assurance of dispersed drinking water, due to its low operating cost, high effluent quality, stable flux, and no need for backwashing. However, the disadvantages of GDM, such as lower stable flux and limited removal capacity for some contaminants, limit its popularization and application. Based on the research and application requirements for the optimization and improvement of water purification efficiency of GDM, this paper summarizes the research progress in strategies for regulating GDM efficiency from the perspectives of stable flux, contaminant removal efficiency, membrane pollution control, and membrane cleaning. This paper discusses the improvement of influent water quality, structural control of the bio-cake layer, optimization of operating parameters, configuration of membrane components, modification of membrane materials, and the role of combined technologies in improving the water purification efficiency of GDM. It also expounds membrane pollution control methods and membrane cleaning strategies, and looks into the future research and practical directions around GDM technology to provide support in expanding the scope of use of GDM, and accelerating the application of GDM technology in practical projects including water plants.
Gravity-driven membrane filtration (GDM) technology has shown significant advantages in the field of water treatment, especially in the safety assurance of dispersed drinking water, due to its low operating cost, high effluent quality, stable flux, and no need for backwashing. However, the disadvantages of GDM, such as lower stable flux and limited removal capacity for some contaminants, limit its popularization and application. Based on the research and application requirements for the optimization and improvement of water purification efficiency of GDM, this paper summarizes the research progress in strategies for regulating GDM efficiency from the perspectives of stable flux, contaminant removal efficiency, membrane pollution control, and membrane cleaning. This paper discusses the improvement of influent water quality, structural control of the bio-cake layer, optimization of operating parameters, configuration of membrane components, modification of membrane materials, and the role of combined technologies in improving the water purification efficiency of GDM. It also expounds membrane pollution control methods and membrane cleaning strategies, and looks into the future research and practical directions around GDM technology to provide support in expanding the scope of use of GDM, and accelerating the application of GDM technology in practical projects including water plants.
2023, 41(9): 18-28.
doi: 10.13205/j.hjgc.202309003
Abstract:
With the aggravation of water pollution and the increasing attention to the safety of drinking water, it is urgent to develop more efficient and low-carbon water treatment processes that could be applied to complex and polluted aquatic environment. As a green and multifunctional agent for water treatment, ferrate has broad application prospects in drinking water treatment. In this paper, the research results of Fe(Ⅵ) in the field of drinking water treatment in recent years were reviewed. The oxidation characteristics and reaction mechanisms of Fe(Ⅵ), as well as the adsorption characteristics of iron oxide/hydroxide particles generated via Fe(Ⅵ) reduction were introduced here. The strategies to enhance the oxidation and adsorption efficiency of Fe(Ⅵ) for pollutants removal were expounded. The efficiency and mechanism of Fe(Ⅵ) to oxidize organic pollutants, to control the formation of disinfection by-products, to remove heavy metal ions in water, to enhance coagulation and to mitigate membrane pollution were discussed. Finally, the application prospect and development trend of Fe(Ⅵ) in drinking water treatment were prospected.
With the aggravation of water pollution and the increasing attention to the safety of drinking water, it is urgent to develop more efficient and low-carbon water treatment processes that could be applied to complex and polluted aquatic environment. As a green and multifunctional agent for water treatment, ferrate has broad application prospects in drinking water treatment. In this paper, the research results of Fe(Ⅵ) in the field of drinking water treatment in recent years were reviewed. The oxidation characteristics and reaction mechanisms of Fe(Ⅵ), as well as the adsorption characteristics of iron oxide/hydroxide particles generated via Fe(Ⅵ) reduction were introduced here. The strategies to enhance the oxidation and adsorption efficiency of Fe(Ⅵ) for pollutants removal were expounded. The efficiency and mechanism of Fe(Ⅵ) to oxidize organic pollutants, to control the formation of disinfection by-products, to remove heavy metal ions in water, to enhance coagulation and to mitigate membrane pollution were discussed. Finally, the application prospect and development trend of Fe(Ⅵ) in drinking water treatment were prospected.
2023, 41(9): 29-35.
doi: 10.13205/j.hjgc.202309004
Abstract:
Heavy metals enter the environment in the process of production and consumption, form a complex, dynamic, and long-chain migration system, which seriously threatens the ecological balance and human health. The traditional prevention and control system with a single medium and factor as the object is difficult to realize the comprehensive innovation of technologies for the prevention and control of heavy metal pollution. Establishing a systematic theory, which synchronously includes the effects of multi-media and multi-factor, has become the core of developing the new generation of technologies. Herein, based on the current characteristics of heavy metal pollution and the theoretical and technological research status of pollution prevention and control in China, a thought of constructing the whole chain of heavy metal pollution prevention and control theory involved "traceability-discrimination-transformation-regression" was proposed centering on the whole life cycle concept. The limitations in the theoretical and technical research of heavy metal pollution control were first generalized. Five major challenges in the development of novel technology for heavy metal pollution prevention and control were subsequently summarized. The feasibility of the research on whole-life cycle prevention and control systems of heavy metal pollution to meet these challenges was discussed. Finally, the future development direction of heavy metal pollution prevention and control was further prospected. In short, with continuous research of relevant theories and methods and continuous breakthrough of key technologies, the construction of the whole-life cycle model and theoretical method for prevention and control of heavy metal pollution will provide significant theoretical support for improving the quality environment with heavy metal pollution and developing novel management technology in China.
Heavy metals enter the environment in the process of production and consumption, form a complex, dynamic, and long-chain migration system, which seriously threatens the ecological balance and human health. The traditional prevention and control system with a single medium and factor as the object is difficult to realize the comprehensive innovation of technologies for the prevention and control of heavy metal pollution. Establishing a systematic theory, which synchronously includes the effects of multi-media and multi-factor, has become the core of developing the new generation of technologies. Herein, based on the current characteristics of heavy metal pollution and the theoretical and technological research status of pollution prevention and control in China, a thought of constructing the whole chain of heavy metal pollution prevention and control theory involved "traceability-discrimination-transformation-regression" was proposed centering on the whole life cycle concept. The limitations in the theoretical and technical research of heavy metal pollution control were first generalized. Five major challenges in the development of novel technology for heavy metal pollution prevention and control were subsequently summarized. The feasibility of the research on whole-life cycle prevention and control systems of heavy metal pollution to meet these challenges was discussed. Finally, the future development direction of heavy metal pollution prevention and control was further prospected. In short, with continuous research of relevant theories and methods and continuous breakthrough of key technologies, the construction of the whole-life cycle model and theoretical method for prevention and control of heavy metal pollution will provide significant theoretical support for improving the quality environment with heavy metal pollution and developing novel management technology in China.
2023, 41(9): 36-45.
doi: 10.13205/j.hjgc.202309005
Abstract:
Urban-rural rivers and lakes exert tremendous functionality and value in flood control and drainage, water supply assurance, water quality improvement, landscape culture service, etc. However, the increasing impact of intense human activities and climate change poses multiple stressors on river-lake systems, severely disrupting their ecological functions. To resuscitate the ecological health of rivers and lakes, numerous river-lake hydrological connectivity projects have been implemented both domestically and internationally. Despite achieving a series of accomplishments, the connectivity projects have also revealed delayed ecological and environmental negative impacts, exacerbating pre-existing ecological issues in certain regions. Therefore, this study focuses on the evolution and drivers of urban-rural rivers and lakes system, with a particular emphasis on clarifying the positive and negative eco-environmental effects of urban-rural rivers and lakes connectivity on water quantity, quality, temperature, salinity, and ecology, and further proposes future research trends. The study could provide a scientific basis for mitigating or eliminating the negative effects and enhancing the positive effects of urban-rural rivers and lakes connectivity in the future.
Urban-rural rivers and lakes exert tremendous functionality and value in flood control and drainage, water supply assurance, water quality improvement, landscape culture service, etc. However, the increasing impact of intense human activities and climate change poses multiple stressors on river-lake systems, severely disrupting their ecological functions. To resuscitate the ecological health of rivers and lakes, numerous river-lake hydrological connectivity projects have been implemented both domestically and internationally. Despite achieving a series of accomplishments, the connectivity projects have also revealed delayed ecological and environmental negative impacts, exacerbating pre-existing ecological issues in certain regions. Therefore, this study focuses on the evolution and drivers of urban-rural rivers and lakes system, with a particular emphasis on clarifying the positive and negative eco-environmental effects of urban-rural rivers and lakes connectivity on water quantity, quality, temperature, salinity, and ecology, and further proposes future research trends. The study could provide a scientific basis for mitigating or eliminating the negative effects and enhancing the positive effects of urban-rural rivers and lakes connectivity in the future.
2023, 41(9): 46-53.
doi: 10.13205/j.hjgc.202309006
Abstract:
In the era of Digital and Data Economy, the development of Smart Water has become the focus and orientation of whole industry. Based on multiple industry surveys and field practice reports, this article analyzes and elaborates on the demand, driving forces and application cases of Smart Water in China. Also it discussed the scientific research progress in Smart Water related technology and products, highlighted with several breakthroughs on AI, Carbon Emission modeling, Digital Twin, and smart field devices for real-time monitoring and controlling. Then, the key bottleneck issues in the development of the Smart Water industry were summarized, including cognitive revolution on digital transformation, lack of industrial standards and cross-disciplinary talent. Finally, the development trend of smart water was prospected.
In the era of Digital and Data Economy, the development of Smart Water has become the focus and orientation of whole industry. Based on multiple industry surveys and field practice reports, this article analyzes and elaborates on the demand, driving forces and application cases of Smart Water in China. Also it discussed the scientific research progress in Smart Water related technology and products, highlighted with several breakthroughs on AI, Carbon Emission modeling, Digital Twin, and smart field devices for real-time monitoring and controlling. Then, the key bottleneck issues in the development of the Smart Water industry were summarized, including cognitive revolution on digital transformation, lack of industrial standards and cross-disciplinary talent. Finally, the development trend of smart water was prospected.
2023, 41(9): 54-60.
doi: 10.13205/j.hjgc.202309007
Abstract:
At present, the source substitution technology and process control technology of volatile organic compounds (VOCs) in China need to be promoted, and the terminal treatment technology still plays a significant role in ensuring the emission reduction effect of VOCs. Based on the investigation and on-site monitoring, the application status of VOCs treatment techniques in China are obtained, and the technology evaluation and prospects are carried out. The results show that activated carbon adsorption, photocatalysis/photooxidation and their combination are the main VOCs treatment techniques in various industries, accounting for about 86.38%, and there are differences in the application of VOCs treatment techniques in different industries. The measured average removal efficiencies of combustion and its combination technology are the highest, 81.74% and 89.81%, respectively. The measured average removal efficiencies of other non-combustion techniques are all below 80%, especially the average and median measured removal efficiencies of activated carbon adsorption, photocatalysis/photooxidation and their combination technology commonly used by enterprises are lower than 50%, cannot meet the requirements of China's national standards. In practical application, problems such as improper selection of VOCs treatment technology, unreasonable process design, low attention to pretreatment, and unregular operation are more common. In the future, VOCs treatment techniques need to be continuously optimized, upgraded, and innovated, to achieve the synergies of pollution control and carbon reduction.
At present, the source substitution technology and process control technology of volatile organic compounds (VOCs) in China need to be promoted, and the terminal treatment technology still plays a significant role in ensuring the emission reduction effect of VOCs. Based on the investigation and on-site monitoring, the application status of VOCs treatment techniques in China are obtained, and the technology evaluation and prospects are carried out. The results show that activated carbon adsorption, photocatalysis/photooxidation and their combination are the main VOCs treatment techniques in various industries, accounting for about 86.38%, and there are differences in the application of VOCs treatment techniques in different industries. The measured average removal efficiencies of combustion and its combination technology are the highest, 81.74% and 89.81%, respectively. The measured average removal efficiencies of other non-combustion techniques are all below 80%, especially the average and median measured removal efficiencies of activated carbon adsorption, photocatalysis/photooxidation and their combination technology commonly used by enterprises are lower than 50%, cannot meet the requirements of China's national standards. In practical application, problems such as improper selection of VOCs treatment technology, unreasonable process design, low attention to pretreatment, and unregular operation are more common. In the future, VOCs treatment techniques need to be continuously optimized, upgraded, and innovated, to achieve the synergies of pollution control and carbon reduction.
2023, 41(9): 61-71.
doi: 10.13205/j.hjgc.202309008
Abstract:
A 10000 t/a amine-based carbon capture device was designed and constructed in a power plant, using blend amine solvent. Under the design conditions, the flue gas flow was 5877 Nm3/h, the solvent circulating flow was 37500 kg/h, the capture efficiency reached 97% above, and the CO2 output was not less than 1.39 t/h; the energy consumption for solvent regeneration decreased by 23%, compared with the traditional monoethanolamine (MEA) solvent. According to the engineering design parameters, the detailed carbon capture process was modelled, and the results reveal relative error was less than 3%, between the key parameters of the modelling and the engineering values. Furthermore, some energy-saving technologies were designed and investigated, including liquid-rich separation, interstage cooling and MVR flash. The effects of energy-saving process parameters were comprehensively explored, such as liquid-rich separation rate, interstage cooling rate and vacuum degree on energy consumption and benefits of the carbon capture system. The results showed that MVR technology could reduce the energy consumption of capture by 15.45%, and then the energy-saving effect was the best, the energy-saving effect of rich liquid diversion and interstage cooling was in a range of 2% to 4.5%. The energy-saving effect was further improved by the combined use of various technologies and optimization of operating parameters. Their energy-saving effect ranked as:interstage cooling+MVR heat pump technology>rich liquid shunt+MVR heat pump technology>energy-saving effect of interstage cooling+rich liquid shunt. The results of this study could provide some guidance for the process system design, energy saving and operation of flue gas carbon capture projects in coal-fired power plants.
A 10000 t/a amine-based carbon capture device was designed and constructed in a power plant, using blend amine solvent. Under the design conditions, the flue gas flow was 5877 Nm3/h, the solvent circulating flow was 37500 kg/h, the capture efficiency reached 97% above, and the CO2 output was not less than 1.39 t/h; the energy consumption for solvent regeneration decreased by 23%, compared with the traditional monoethanolamine (MEA) solvent. According to the engineering design parameters, the detailed carbon capture process was modelled, and the results reveal relative error was less than 3%, between the key parameters of the modelling and the engineering values. Furthermore, some energy-saving technologies were designed and investigated, including liquid-rich separation, interstage cooling and MVR flash. The effects of energy-saving process parameters were comprehensively explored, such as liquid-rich separation rate, interstage cooling rate and vacuum degree on energy consumption and benefits of the carbon capture system. The results showed that MVR technology could reduce the energy consumption of capture by 15.45%, and then the energy-saving effect was the best, the energy-saving effect of rich liquid diversion and interstage cooling was in a range of 2% to 4.5%. The energy-saving effect was further improved by the combined use of various technologies and optimization of operating parameters. Their energy-saving effect ranked as:interstage cooling+MVR heat pump technology>rich liquid shunt+MVR heat pump technology>energy-saving effect of interstage cooling+rich liquid shunt. The results of this study could provide some guidance for the process system design, energy saving and operation of flue gas carbon capture projects in coal-fired power plants.
2023, 41(9): 72-79.
doi: 10.13205/j.hjgc.202309009
Abstract:
The sludge densification system technology (SDST) was applied in a wastewater treatment plant (WWTP) for engineering modification, located in Wuxi, with a designed treatment capacity of 150000 m3/d, and a sludge densification module was added in the external reflux process section to effectively improve sludge settling performance. The inverted AAO (anoxic/anaerobic/oxic) process was adopted in the WWTP with the Phase Ⅰ project (40000 m3/d) and Phase Ⅱ project (110000 m3/d), acting as the experimental group and control group, respectively. After the engineering modification, the densification module was successfully operated for 90 days in a half-scale mode, which maximum treatment capacity was 50% of the original design surplus sludge volume. The removal capacity of TN in the Phase Ⅰ project was significantly improved, and the effluent concentration decreased by 14.7% (from 6.32 mg/L to 5.39 mg/L). During the start-up stage (day 1 to 36), the settling rate of aerobic sludge increased to 1.92 m/h. In the stable and lifting stage (day 42 to 90), the settling rate and SVI30 were (3.62±0.52) m/h and (49.3±5.5) mL/g, respectively, while the counterparts of sludge in the Phase Ⅱ project were (1.93±0.35) m/h and (59.3±5.5) mL/g. The densification device had a stable sludge densification effect so that the densified sludge MLSS was (19.3±2.75) g/L, and the SVI30 was only (36.7±9.0) mL/g. Many small granular flocs in densified sludge were successfully observed through microscopic examination, but the degree of granulation was limited. This study found that the massive fibrous and inert inorganic matters in activated sludge were important factors affecting the operation of the densification module, while a spiral grating was added to ensure its operation. Moreover, the effects of these inorganic substances such as sand, iron salt, and aluminum salt on the system still need to be further discussed. In addition, coupling sand removal measures and adopting full coverage treatment to optimize and transform the densification module were the key to further improving the granulation degree of densification sludge. Our team has successfully applied the SDST in an inverted AAO continuous flow WWTP in China for the first time, providing an important method for the upgrading and modification of existing wastewater treatment plants.
The sludge densification system technology (SDST) was applied in a wastewater treatment plant (WWTP) for engineering modification, located in Wuxi, with a designed treatment capacity of 150000 m3/d, and a sludge densification module was added in the external reflux process section to effectively improve sludge settling performance. The inverted AAO (anoxic/anaerobic/oxic) process was adopted in the WWTP with the Phase Ⅰ project (40000 m3/d) and Phase Ⅱ project (110000 m3/d), acting as the experimental group and control group, respectively. After the engineering modification, the densification module was successfully operated for 90 days in a half-scale mode, which maximum treatment capacity was 50% of the original design surplus sludge volume. The removal capacity of TN in the Phase Ⅰ project was significantly improved, and the effluent concentration decreased by 14.7% (from 6.32 mg/L to 5.39 mg/L). During the start-up stage (day 1 to 36), the settling rate of aerobic sludge increased to 1.92 m/h. In the stable and lifting stage (day 42 to 90), the settling rate and SVI30 were (3.62±0.52) m/h and (49.3±5.5) mL/g, respectively, while the counterparts of sludge in the Phase Ⅱ project were (1.93±0.35) m/h and (59.3±5.5) mL/g. The densification device had a stable sludge densification effect so that the densified sludge MLSS was (19.3±2.75) g/L, and the SVI30 was only (36.7±9.0) mL/g. Many small granular flocs in densified sludge were successfully observed through microscopic examination, but the degree of granulation was limited. This study found that the massive fibrous and inert inorganic matters in activated sludge were important factors affecting the operation of the densification module, while a spiral grating was added to ensure its operation. Moreover, the effects of these inorganic substances such as sand, iron salt, and aluminum salt on the system still need to be further discussed. In addition, coupling sand removal measures and adopting full coverage treatment to optimize and transform the densification module were the key to further improving the granulation degree of densification sludge. Our team has successfully applied the SDST in an inverted AAO continuous flow WWTP in China for the first time, providing an important method for the upgrading and modification of existing wastewater treatment plants.
2023, 41(9): 80-88.
doi: 10.13205/j.hjgc.202309010
Abstract:
Microbial nutrient stimulant, produced after alkaline thermal hydrolysis of activated sludge, are rich in nitrogenous nutrients and stimulant substances that promote plant growth, and have received rising attention in the field of sludge resource utilization and sustainable agricultural development. This study focused on analyzing the basic nutrient characteristics, stimulant composition characteristics, and pollutant content characteristics of microbial nutrient stimulants, and analyzing their potential in land application. Microbial nutrient stimulant was rich in nutrients such as nitrogen, phosphorus, potassium, organic carbon, and minerals that promoted plant growth, with nitrogen and calcium as the main elements. At the same time, the microbial nutrient stimulants also contained stimulant components such as humic acid, fulvic acid, tryptophan, as well as phytohormone substances (indole-3-acetic acid) and chemosensory substances (indole derivatives), a total of 9445 kinds of organic molecules were detected. The heavy metal content of microbial nutrient stimulants was reduced by 47.39% to 100% compared to sludge, and the ecological risk of PAHs and antibiotics was much lower than that of sludge. A summary of the land application effect showed that microbial nutrient stimulants could promote the yield of pakchoi cabbage, reduce the accumulation of heavy metals in pakchoi cabbage, and reduce fertilization costs, by partially replacing chemical fertilizers. By analyzing the dual properties of nutrient and stimulant components of microbial nutrient stimulant, it was suggested that microbial nutrient stimulant had good potential for application in enhancing photosynthesis, antioxidant properties, nutritional quality, and reducing heavy metal accumulation in pakchoi cabbage.
Microbial nutrient stimulant, produced after alkaline thermal hydrolysis of activated sludge, are rich in nitrogenous nutrients and stimulant substances that promote plant growth, and have received rising attention in the field of sludge resource utilization and sustainable agricultural development. This study focused on analyzing the basic nutrient characteristics, stimulant composition characteristics, and pollutant content characteristics of microbial nutrient stimulants, and analyzing their potential in land application. Microbial nutrient stimulant was rich in nutrients such as nitrogen, phosphorus, potassium, organic carbon, and minerals that promoted plant growth, with nitrogen and calcium as the main elements. At the same time, the microbial nutrient stimulants also contained stimulant components such as humic acid, fulvic acid, tryptophan, as well as phytohormone substances (indole-3-acetic acid) and chemosensory substances (indole derivatives), a total of 9445 kinds of organic molecules were detected. The heavy metal content of microbial nutrient stimulants was reduced by 47.39% to 100% compared to sludge, and the ecological risk of PAHs and antibiotics was much lower than that of sludge. A summary of the land application effect showed that microbial nutrient stimulants could promote the yield of pakchoi cabbage, reduce the accumulation of heavy metals in pakchoi cabbage, and reduce fertilization costs, by partially replacing chemical fertilizers. By analyzing the dual properties of nutrient and stimulant components of microbial nutrient stimulant, it was suggested that microbial nutrient stimulant had good potential for application in enhancing photosynthesis, antioxidant properties, nutritional quality, and reducing heavy metal accumulation in pakchoi cabbage.
2023, 41(9): 89-95.
doi: 10.13205/j.hjgc.202309011
Abstract:
Sulfadimethymidine (SMT) is a kind of antibiotic with a good antibacterial effect, which is widely used in the treatment of human and livestock diseases globally. But because it cannot be completely absorbed in the animal body, it will be excreted with feces, and then pollute the natural water body. In this study, natural tourmaline was used as a catalyst to form an electro-Fenton reaction system. Hydrogen peroxide (H2O2) was generated in situ by the cathode. In this paper, the effects of different pH, initial SMT concentration, temperature, current density, and tourmaline dosage on the degradation of SMT were investigated.
Sulfadimethymidine (SMT) is a kind of antibiotic with a good antibacterial effect, which is widely used in the treatment of human and livestock diseases globally. But because it cannot be completely absorbed in the animal body, it will be excreted with feces, and then pollute the natural water body. In this study, natural tourmaline was used as a catalyst to form an electro-Fenton reaction system. Hydrogen peroxide (H2O2) was generated in situ by the cathode. In this paper, the effects of different pH, initial SMT concentration, temperature, current density, and tourmaline dosage on the degradation of SMT were investigated.
2023, 41(9): 96-106.
doi: 10.13205/j.hjgc.202309012
Abstract:
Aerobic granular sludge (AGS) technology is currently one of the promising enhanced technologies for biological wastewater treatment. However, the rapid cultivation of AGS and its long-term operational stability, especially in continuous processes, remain the main challenges faced by the application of this technology. Through literature analysis, this paper analyzes the main causes and potential mechanisms of AGS instability from the physical, chemical, and microbial aspects, and discusses the main strategies for enhancing the stability of granular sludge, namely, selective sludge discharge, particle size optimization, EPS secretion enhancement, bacterial growth rate control, excessive proliferation inhibition of filamentous bacteria, exogenous enhancement and addition of signaling molecule. In view of the complexity of the instability mechanism of AGS and the limitations of a single improvement strategy, the long-term stability of AGS structure needs to be comprehensively managed by a variety of strategies, and future research on AGS goldilocks zone should pay more attention to systematic consideration from the physical, chemical, and microbiological perspectives.
Aerobic granular sludge (AGS) technology is currently one of the promising enhanced technologies for biological wastewater treatment. However, the rapid cultivation of AGS and its long-term operational stability, especially in continuous processes, remain the main challenges faced by the application of this technology. Through literature analysis, this paper analyzes the main causes and potential mechanisms of AGS instability from the physical, chemical, and microbial aspects, and discusses the main strategies for enhancing the stability of granular sludge, namely, selective sludge discharge, particle size optimization, EPS secretion enhancement, bacterial growth rate control, excessive proliferation inhibition of filamentous bacteria, exogenous enhancement and addition of signaling molecule. In view of the complexity of the instability mechanism of AGS and the limitations of a single improvement strategy, the long-term stability of AGS structure needs to be comprehensively managed by a variety of strategies, and future research on AGS goldilocks zone should pay more attention to systematic consideration from the physical, chemical, and microbiological perspectives.
2023, 41(9): 107-113.
doi: 10.13205/j.hjgc.202309013
Abstract:
Reclaimed water could be achieved through advanced wastewater purification technology using constructed wetlands. Water reclamation by constructed wetlands can effectively alleviate the shortage of water resources and address both pollution reduction and carbon reduction needs. However, insufficient carbon/oxygen supplement leads to a low pollutant removal rate and low resource transformation rate, limits the scale-up application of constructed wetlands. Microalgae-based wastewater treatment offers several advantages, including photosynthetic oxygen release, carbon fixation, and efficient resource recovery of pollutants, which has high complementarity with constructed wetlands. This paper thoroughly compared the performance of two coupling modes of microalgae and constructed wetlands in the aspects of carbon/oxygen regulation of water purification mechanism, pollutant removal and resource transformation. The water purification process of the coupled system was analyzed from the perspective of carbon, nitrogen and phosphorus transformation, and the optimal path of adding moderate microalgae biomass in the anoxic area of constructed wetland was proposed. Finally, the paper outlined the future research in this field, focusing on system purification mechanisms and operation efficiency.
Reclaimed water could be achieved through advanced wastewater purification technology using constructed wetlands. Water reclamation by constructed wetlands can effectively alleviate the shortage of water resources and address both pollution reduction and carbon reduction needs. However, insufficient carbon/oxygen supplement leads to a low pollutant removal rate and low resource transformation rate, limits the scale-up application of constructed wetlands. Microalgae-based wastewater treatment offers several advantages, including photosynthetic oxygen release, carbon fixation, and efficient resource recovery of pollutants, which has high complementarity with constructed wetlands. This paper thoroughly compared the performance of two coupling modes of microalgae and constructed wetlands in the aspects of carbon/oxygen regulation of water purification mechanism, pollutant removal and resource transformation. The water purification process of the coupled system was analyzed from the perspective of carbon, nitrogen and phosphorus transformation, and the optimal path of adding moderate microalgae biomass in the anoxic area of constructed wetland was proposed. Finally, the paper outlined the future research in this field, focusing on system purification mechanisms and operation efficiency.
2023, 41(9): 114-123.
doi: 10.13205/j.hjgc.202309014
Abstract:
The spread of antibiotic resistance has become a global public health issue. Drinking water is an important pathway for the migration and dissemination of antibiotic resistance genes (ARGs) to the human body. The ARGs and their potential exposure risks in drinking water have attracted widespread attention. This review summarized the distribution of ARGs in drinking water worldwide and its drivers based on published research on ARGs in drinking water. It explored the assessment methods applicable to characterize the exposure dose and risk of ARGs in drinking water, and discussed the effects and limitations of conventional drinking water treatment technologies in controlling ARGs. Further studies were required to conduct systematic assessments of antibiotic resistance risks in drinking water from multiple dimensions (e.g. transmissibility and human pathogenicity) and develop novel water treatment technologies to enhance the removal of ARGs.
The spread of antibiotic resistance has become a global public health issue. Drinking water is an important pathway for the migration and dissemination of antibiotic resistance genes (ARGs) to the human body. The ARGs and their potential exposure risks in drinking water have attracted widespread attention. This review summarized the distribution of ARGs in drinking water worldwide and its drivers based on published research on ARGs in drinking water. It explored the assessment methods applicable to characterize the exposure dose and risk of ARGs in drinking water, and discussed the effects and limitations of conventional drinking water treatment technologies in controlling ARGs. Further studies were required to conduct systematic assessments of antibiotic resistance risks in drinking water from multiple dimensions (e.g. transmissibility and human pathogenicity) and develop novel water treatment technologies to enhance the removal of ARGs.
2023, 41(9): 124-132.
doi: 10.13205/j.hjgc.202309015
Abstract:
Biodegradable plastics have attracted wide attention because of their environmental friendliness, but the carbon emission in the waste disposal process is still unclear. With the development and application of disposal technologies, the differences in carbon emissions of these technologies are worth exploring. To reveal the carbon emissions of different disposal technologies for waste biodegradable plastics, this study compares the indirect carbon emissions from operation energy consumption, direct carbon emissions from plastic decomposition, and carbon offset from resource recovery, based on the emission factor and mass balance method. The results showed that the net carbon emissions per ton of waste biodegradable plastics were as follows:landfill > incineration > industrial composting > chemical recovery > anaerobic fermentation > mechanical recycling. Because of the resource recovery of plastic and biogas, mechanical recycling and anaerobic fermentation had a net carbon emission of -842.33 kg CO2eq and -341.55 kg CO2eq, respectively, showing their better potential for carbon reduction. Among them, the indirect carbon emission, direct carbon emission, and carbon offset of mechanical recycling were 0.62~22.96, 0.13~0.52, and 0.93~1.58 times of other disposal technologies, respectively. And those of anaerobic fermentation were 0.09~2.11, 0.26~1.93, and 0.59~0.85 times, respectively. This indicated that mechanical recycling has higher energy consumption and carbon offsetting effects than anaerobic fermentation. However, the low efficiency and poor performance of recycled products limits the development of mechanical recycling for waste biodegradable plastics. Anaerobic fermentation has more development prospects from the perspective of carbon reduction potential. In addition, reducing operation energy consumption, promoting resource recovery, and giving full play to carbon offset potential are the main measures to achieve carbon emission reduction in the disposal of waste biodegradable plastics. From the perspective of striving for Double Carbon Goal, this study provides a reference for the selection of waste biodegradable plastics disposal technology.
Biodegradable plastics have attracted wide attention because of their environmental friendliness, but the carbon emission in the waste disposal process is still unclear. With the development and application of disposal technologies, the differences in carbon emissions of these technologies are worth exploring. To reveal the carbon emissions of different disposal technologies for waste biodegradable plastics, this study compares the indirect carbon emissions from operation energy consumption, direct carbon emissions from plastic decomposition, and carbon offset from resource recovery, based on the emission factor and mass balance method. The results showed that the net carbon emissions per ton of waste biodegradable plastics were as follows:landfill > incineration > industrial composting > chemical recovery > anaerobic fermentation > mechanical recycling. Because of the resource recovery of plastic and biogas, mechanical recycling and anaerobic fermentation had a net carbon emission of -842.33 kg CO2eq and -341.55 kg CO2eq, respectively, showing their better potential for carbon reduction. Among them, the indirect carbon emission, direct carbon emission, and carbon offset of mechanical recycling were 0.62~22.96, 0.13~0.52, and 0.93~1.58 times of other disposal technologies, respectively. And those of anaerobic fermentation were 0.09~2.11, 0.26~1.93, and 0.59~0.85 times, respectively. This indicated that mechanical recycling has higher energy consumption and carbon offsetting effects than anaerobic fermentation. However, the low efficiency and poor performance of recycled products limits the development of mechanical recycling for waste biodegradable plastics. Anaerobic fermentation has more development prospects from the perspective of carbon reduction potential. In addition, reducing operation energy consumption, promoting resource recovery, and giving full play to carbon offset potential are the main measures to achieve carbon emission reduction in the disposal of waste biodegradable plastics. From the perspective of striving for Double Carbon Goal, this study provides a reference for the selection of waste biodegradable plastics disposal technology.
2023, 41(9): 133-139.
doi: 10.13205/j.hjgc.202309016
Abstract:
Aerobic remediation technology for old MSW landfills has been widely used in China due to its reduction performance on methane gas, and is expected as an important technical means of landfill remediation under the background of China's Dual Carbon Goals. The carbon emission accounting models commonly used at home and abroad are difficult to represent the carbon emission reduction of landfill aerobic remediation process. In this paper, the aerobic restoration project of Tianjin Huaming landfill was taken as the research object, and the engineering mechanical properties of the landfill, biochemical properties of waste degradation, and biochemical properties of landfill leachate were analyzed within 300 days of aerobic restoration work since May 2019. Two principal components were obtained, and a regression model of methane concentration in the landfill was established using the principal components analysis. This model can analyze and predict the decreasing law of methane gas concentration in landfill bodies during aerobic restoration, and then calculate the methane reduction of landfill aerobic restoration compared with the traditional anaerobic sealing field. It provides a theoretical basis for the calculation of carbon emission reduction of landfill aerobic restoration, and can be applied to judge aerobic restoration process when landfill showes the characteristic value of methane concentration stabilization.
Aerobic remediation technology for old MSW landfills has been widely used in China due to its reduction performance on methane gas, and is expected as an important technical means of landfill remediation under the background of China's Dual Carbon Goals. The carbon emission accounting models commonly used at home and abroad are difficult to represent the carbon emission reduction of landfill aerobic remediation process. In this paper, the aerobic restoration project of Tianjin Huaming landfill was taken as the research object, and the engineering mechanical properties of the landfill, biochemical properties of waste degradation, and biochemical properties of landfill leachate were analyzed within 300 days of aerobic restoration work since May 2019. Two principal components were obtained, and a regression model of methane concentration in the landfill was established using the principal components analysis. This model can analyze and predict the decreasing law of methane gas concentration in landfill bodies during aerobic restoration, and then calculate the methane reduction of landfill aerobic restoration compared with the traditional anaerobic sealing field. It provides a theoretical basis for the calculation of carbon emission reduction of landfill aerobic restoration, and can be applied to judge aerobic restoration process when landfill showes the characteristic value of methane concentration stabilization.
2023, 41(9): 140-145.
doi: 10.13205/j.hjgc.202309017
Abstract:
Based on patent analysis, this paper combs the patents applied in the field of environmental monitoring in Tianjin from 2018 to 2022, and focuses on the development status and existing problems of eco-environmental monitoring technology in Tianjin, and puts forward suggestions to further promote the environmental monitoring industry innovation in Tianjin. The results show that the ecological environment monitoring technology in Tianjin has made great progress in the past five years. Binhai New Area and Nankai District are hot distribution areas of environmental monitoring technology. Among the patent applicants, enterprises account for 70.23%, being the main body of technological innovation. However, among the top 10 patent applicants, universities and research institutions represented by Tianjin University, account for 60%. The subcategory with the highest proportion is testing or analyzing materials by measuring their chemical or physical properties (G01N subcategory in the G category), and the monitoring technology mainly focuses on equipment improvement and sampling. In the past five years, the number of patents in Tianjin has stabilized, and the vitality of technological innovation shows a decline trend. It is recommended that Tianjin increase support in the environmental monitoring industry, guide technical research and layout in an orderly manner through planning and traction, increase support for the transformation of environmental science and technology innovation achievements, cultivate leading enterprises, and develop into a regional characteristic environmental monitoring industry.
Based on patent analysis, this paper combs the patents applied in the field of environmental monitoring in Tianjin from 2018 to 2022, and focuses on the development status and existing problems of eco-environmental monitoring technology in Tianjin, and puts forward suggestions to further promote the environmental monitoring industry innovation in Tianjin. The results show that the ecological environment monitoring technology in Tianjin has made great progress in the past five years. Binhai New Area and Nankai District are hot distribution areas of environmental monitoring technology. Among the patent applicants, enterprises account for 70.23%, being the main body of technological innovation. However, among the top 10 patent applicants, universities and research institutions represented by Tianjin University, account for 60%. The subcategory with the highest proportion is testing or analyzing materials by measuring their chemical or physical properties (G01N subcategory in the G category), and the monitoring technology mainly focuses on equipment improvement and sampling. In the past five years, the number of patents in Tianjin has stabilized, and the vitality of technological innovation shows a decline trend. It is recommended that Tianjin increase support in the environmental monitoring industry, guide technical research and layout in an orderly manner through planning and traction, increase support for the transformation of environmental science and technology innovation achievements, cultivate leading enterprises, and develop into a regional characteristic environmental monitoring industry.
2023, 41(9): 146-155.
doi: 10.13205/j.hjgc.202309018
Abstract:
The resource utilization of organic solid waste plays an important role in energy conservation, pollution emission reduction, and sustainable development. Anaerobic digestion, through biological metabolism, offers a promising approach to converting organic solid waste into cleaner fuel methane for energy recovery. However, the current efficiency of methane production in anaerobic digestion technology remains limited due to the intricate reaction process and the impact of toxic and harmful intermediates. Carbon-based conductive materials (CCMs) have shown the potential in enhancing methane production efficiency during anaerobic digestion. Nevertheless, the underlying mechanism of CCMs influencing methane production from anaerobic digestion of organic solid waste remains unclear. Building upon prior research, this paper comprehensively analyzes the effects of CCMs on the methanogenic efficiency of anaerobic digestion. It explores the microbiological mechanisms of CCMs in enhancing methanogenic efficiency from the perspectives of enzyme activity and microbial community. Furthermore, it investigates the mechanisms of CCMs enhancing direct interspecies electron transfer, while also providing an energy and economic perspective on the application of CCMs to improve the methanogenic efficiency of anaerobic digestion of organic solid waste. The findings presented in this paper establish a theoretical basis and offer technical support for the utilization of CCMs in anaerobic digestion applications.
The resource utilization of organic solid waste plays an important role in energy conservation, pollution emission reduction, and sustainable development. Anaerobic digestion, through biological metabolism, offers a promising approach to converting organic solid waste into cleaner fuel methane for energy recovery. However, the current efficiency of methane production in anaerobic digestion technology remains limited due to the intricate reaction process and the impact of toxic and harmful intermediates. Carbon-based conductive materials (CCMs) have shown the potential in enhancing methane production efficiency during anaerobic digestion. Nevertheless, the underlying mechanism of CCMs influencing methane production from anaerobic digestion of organic solid waste remains unclear. Building upon prior research, this paper comprehensively analyzes the effects of CCMs on the methanogenic efficiency of anaerobic digestion. It explores the microbiological mechanisms of CCMs in enhancing methanogenic efficiency from the perspectives of enzyme activity and microbial community. Furthermore, it investigates the mechanisms of CCMs enhancing direct interspecies electron transfer, while also providing an energy and economic perspective on the application of CCMs to improve the methanogenic efficiency of anaerobic digestion of organic solid waste. The findings presented in this paper establish a theoretical basis and offer technical support for the utilization of CCMs in anaerobic digestion applications.
2023, 41(9): 156-165.
doi: 10.13205/j.hjgc.202309019
Abstract:
Anaerobic digestion, an effective approach to the harmless treatment of organic waste and recovery of energy and materials, has been widely used in practical engineering. However, the high concentration of ammonia nitrogen produced during anaerobic digestion seriously inhibits substrate degradation and biogas production, which is a vital factor leading to the decline of system performance, and even the collapse of the reaction system. The essence of anaerobic digestion is the process of using organic matter to produce methane by large numbers of microbes, such as hydrolyzing-acidifying and syntrophic acetogenic bacteria and methanogenic archaea. The analysis of the microbial mechanism of ammonia inhibition is conducive to clarifying the essential causes of instability. However, the biological mechanism of ammonia suppression on anaerobic digestion is rarely reviewed. This paper first systematically summarizes the remodeling characteristics of microbial communities under ammonia stress. The influence of high ammonia on the vital phenotypes of cells is then introduced. Finally, the evolution of enzymes and lipid molecules under ammonia stress is discussed. This work will expand the understanding of ammonia inhibition behaviors. Future studies are recommended to reveal the molecular mechanism of microbial interaction under ammonia stress and develop disinhibition methods based on ammonia-inhibiting mechanisms.
Anaerobic digestion, an effective approach to the harmless treatment of organic waste and recovery of energy and materials, has been widely used in practical engineering. However, the high concentration of ammonia nitrogen produced during anaerobic digestion seriously inhibits substrate degradation and biogas production, which is a vital factor leading to the decline of system performance, and even the collapse of the reaction system. The essence of anaerobic digestion is the process of using organic matter to produce methane by large numbers of microbes, such as hydrolyzing-acidifying and syntrophic acetogenic bacteria and methanogenic archaea. The analysis of the microbial mechanism of ammonia inhibition is conducive to clarifying the essential causes of instability. However, the biological mechanism of ammonia suppression on anaerobic digestion is rarely reviewed. This paper first systematically summarizes the remodeling characteristics of microbial communities under ammonia stress. The influence of high ammonia on the vital phenotypes of cells is then introduced. Finally, the evolution of enzymes and lipid molecules under ammonia stress is discussed. This work will expand the understanding of ammonia inhibition behaviors. Future studies are recommended to reveal the molecular mechanism of microbial interaction under ammonia stress and develop disinhibition methods based on ammonia-inhibiting mechanisms.
ALKALINE-THERMAL HYDROLYSIS OF SEWAGE SLUDGE DIGESTATE AND ITS PERFORMANCE IN ANAEROBIC FERMENTATION
2023, 41(9): 166-173.
doi: 10.13205/j.hjgc.202309020
Abstract:
To recover and reuse the organic matter in sewage sludge digestate, this work adopted alkaline-thermal hydrolysis to treat the digestate, exploring the effects of different conditions on its disintegration and organics dissolution efficiency. The optimal conditions for alkaline-thermal hydrolysis of sewage sludge digestate were determined as pH=13, T=80℃, and t=8 h. Under these conditions, the disintegration efficiency of sewage sludge digestate achieved 40.9%, with the dissolution efficiency of COD, protein, and polysaccharide of 722.2, 79.7, and 73.7 mg/g VSS, respectively. The sewage sludge digestate after alkaline-thermal hydrolysis was used as substrates for anaerobic fermentation to produce methane. The effect of initial pH on anaerobic fermentation was further investigated. It was found that the best methane yield was achieved at the initial pH of 13, and the COD removal efficiency was 61.1% with a methane yield of 65.0 mL/g VSS and a methane proportion of 81.0% in the produced biogas. This work confirms that alkaline-thermal hydrolysis can improve the biodegradability of sewage sludge digestate, and its potential in producing methane through anaerobic fermentation.
To recover and reuse the organic matter in sewage sludge digestate, this work adopted alkaline-thermal hydrolysis to treat the digestate, exploring the effects of different conditions on its disintegration and organics dissolution efficiency. The optimal conditions for alkaline-thermal hydrolysis of sewage sludge digestate were determined as pH=13, T=80℃, and t=8 h. Under these conditions, the disintegration efficiency of sewage sludge digestate achieved 40.9%, with the dissolution efficiency of COD, protein, and polysaccharide of 722.2, 79.7, and 73.7 mg/g VSS, respectively. The sewage sludge digestate after alkaline-thermal hydrolysis was used as substrates for anaerobic fermentation to produce methane. The effect of initial pH on anaerobic fermentation was further investigated. It was found that the best methane yield was achieved at the initial pH of 13, and the COD removal efficiency was 61.1% with a methane yield of 65.0 mL/g VSS and a methane proportion of 81.0% in the produced biogas. This work confirms that alkaline-thermal hydrolysis can improve the biodegradability of sewage sludge digestate, and its potential in producing methane through anaerobic fermentation.
2023, 41(9): 174-180.
doi: 10.13205/j.hjgc.202309021
Abstract:
Urban wastewater treatment plants can be a potential source of resource, energy, and water. How to maximize the realization of resource and energy recovery, water recycling and being environment-friendly, has become the leading development direction of urban wastewater treatment. In order to promote the practices of wastewater resources and energy utilization, and improve its technical level, China Urban Water Association released the Technical Specification for Resource and Energy Recovery from Municipal Wastewater in July 2023. The technical specification, for the first time in China, put forward the technical route, parameters, and operation and management points in wastewater resources and energy recovery, which can provide guidance for the selection of treatment technology or process, engineering design, and operation optimization. The implementation of this technical specification is of positive significance for realizing the transformation of wastewater treatment plants into resource and energy plants and promoting the green, low-carbon, and high-quality development of urban wastewater treatment in China.
Urban wastewater treatment plants can be a potential source of resource, energy, and water. How to maximize the realization of resource and energy recovery, water recycling and being environment-friendly, has become the leading development direction of urban wastewater treatment. In order to promote the practices of wastewater resources and energy utilization, and improve its technical level, China Urban Water Association released the Technical Specification for Resource and Energy Recovery from Municipal Wastewater in July 2023. The technical specification, for the first time in China, put forward the technical route, parameters, and operation and management points in wastewater resources and energy recovery, which can provide guidance for the selection of treatment technology or process, engineering design, and operation optimization. The implementation of this technical specification is of positive significance for realizing the transformation of wastewater treatment plants into resource and energy plants and promoting the green, low-carbon, and high-quality development of urban wastewater treatment in China.
2023, 41(9): 181-186.
doi: 10.13205/j.hjgc.202309022
Abstract:
When environmental pollution worsens and climate change intensifies, sustainable development of human society faces severe challenges. As a crucial component, wastewater treatment plays an essential role, and constructing carbon-neutral wastewater treatment plants to achieve both pollution and carbon reduction becomes a critical step towards the Dual Carbon Goals. In this paper, we systematically analyze the road map for constructing carbon-neutral wastewater treatment plants, focusing on the aspects such as energy consumption control and energy self-sufficiency in the treatment processes, reduction of chemicals and carbon source utilization in treatment processes, and recycling of water and valuable materials. We also evaluate the carbon reduction benefits of these relevant measures. Looking to the future, measures to promote energy optimization and usage of cleaner energy, reduce carbon and chemical consumption, and enhance water reclamation and the circular utilization of valuable materials, combined with comprehensive approaches involving technological innovation, policy-making, and urban planning, will help accelerate the carbon-neutral process of wastewater treatment plants construction and establish blue routes for constructing carbon-neutral cities.
When environmental pollution worsens and climate change intensifies, sustainable development of human society faces severe challenges. As a crucial component, wastewater treatment plays an essential role, and constructing carbon-neutral wastewater treatment plants to achieve both pollution and carbon reduction becomes a critical step towards the Dual Carbon Goals. In this paper, we systematically analyze the road map for constructing carbon-neutral wastewater treatment plants, focusing on the aspects such as energy consumption control and energy self-sufficiency in the treatment processes, reduction of chemicals and carbon source utilization in treatment processes, and recycling of water and valuable materials. We also evaluate the carbon reduction benefits of these relevant measures. Looking to the future, measures to promote energy optimization and usage of cleaner energy, reduce carbon and chemical consumption, and enhance water reclamation and the circular utilization of valuable materials, combined with comprehensive approaches involving technological innovation, policy-making, and urban planning, will help accelerate the carbon-neutral process of wastewater treatment plants construction and establish blue routes for constructing carbon-neutral cities.
2023, 41(9): 187-193.
doi: 10.13205/j.hjgc.202309023
Abstract:
Sulfonamides (SAs) are a class of the most frequently used antibiotics. It has been detected in sewage treatment effluent and natural water environments and has potential harm to aquatic animals, plants, microorganisms, and human health. But at present, the degradation effect of SAs in water by conventional biological methods is not significant. As one of the effective methods to remove SAs from water, oxidation is a research hotspot of water treatment. In view of the efficacy mechanism and harm of sulfonamide in water, the research progress in the oxidative degradation of sulfonamide in water was reviewed, and the internal relations between different oxidation methods, reaction pathways, and the toxicity of the products were clarified. It was also pointed out that advanced oxidation methods were more effective in accelerating sulfonamide removal, while direct oxidation was more advantageous in reducing the accumulation of highly toxic intermediates and reducing antibiotic resistance genes. Therefore, the development of more efficient oxidation methods requires close attention to the accumulation of sulfonamide intermediates and antibiotic resistance.
Sulfonamides (SAs) are a class of the most frequently used antibiotics. It has been detected in sewage treatment effluent and natural water environments and has potential harm to aquatic animals, plants, microorganisms, and human health. But at present, the degradation effect of SAs in water by conventional biological methods is not significant. As one of the effective methods to remove SAs from water, oxidation is a research hotspot of water treatment. In view of the efficacy mechanism and harm of sulfonamide in water, the research progress in the oxidative degradation of sulfonamide in water was reviewed, and the internal relations between different oxidation methods, reaction pathways, and the toxicity of the products were clarified. It was also pointed out that advanced oxidation methods were more effective in accelerating sulfonamide removal, while direct oxidation was more advantageous in reducing the accumulation of highly toxic intermediates and reducing antibiotic resistance genes. Therefore, the development of more efficient oxidation methods requires close attention to the accumulation of sulfonamide intermediates and antibiotic resistance.
2023, 41(9): 194-200.
doi: 10.13205/j.hjgc.202309024
Abstract:
With the rapid development of modern cities and industrialization, wastewater treatment plants (WWTPs) have become essential facilities for protecting water environments. However, the tailwater discharged from a WWTP still has adverse effects on the effluent-receiving area (ERA). Long-term discharge of WWTP effluents into coastal areas has led to deteriorating seawater quality, but the response of coastal microbial communities is not yet well understood. This study chose two ERAs, named as JX and SY respectively, on the north and south coast of Hangzhou Bay, China, as the study areas. Environmental quality surveys were conducted, and microbial communities in sediment were analyzed using metagenomic sequencing to assess the potential impacts of wastewater discharge on microbial community structures and functions. The results indicated that land-based discharge had impacts on microbial communities in the sediment of the ERAs. JX and SY exhibited distinct community compositions, with key environmental factors being water chemical oxygen demand (COD) and water depth. Functional differences were also observed between the two ERAs, particularly in carbon metabolism. In JX, differential genes related to methane metabolism were found; while in SY, differential genes related to sugar fermentation pathways were identified. Water COD and sediment total organic carbon (TOC) and petroleum compounds were identified as the major influence factors. These findings are of great importance for the environmental management of ERA and provide scientific reference for improving the discharge standards of WWTP.
With the rapid development of modern cities and industrialization, wastewater treatment plants (WWTPs) have become essential facilities for protecting water environments. However, the tailwater discharged from a WWTP still has adverse effects on the effluent-receiving area (ERA). Long-term discharge of WWTP effluents into coastal areas has led to deteriorating seawater quality, but the response of coastal microbial communities is not yet well understood. This study chose two ERAs, named as JX and SY respectively, on the north and south coast of Hangzhou Bay, China, as the study areas. Environmental quality surveys were conducted, and microbial communities in sediment were analyzed using metagenomic sequencing to assess the potential impacts of wastewater discharge on microbial community structures and functions. The results indicated that land-based discharge had impacts on microbial communities in the sediment of the ERAs. JX and SY exhibited distinct community compositions, with key environmental factors being water chemical oxygen demand (COD) and water depth. Functional differences were also observed between the two ERAs, particularly in carbon metabolism. In JX, differential genes related to methane metabolism were found; while in SY, differential genes related to sugar fermentation pathways were identified. Water COD and sediment total organic carbon (TOC) and petroleum compounds were identified as the major influence factors. These findings are of great importance for the environmental management of ERA and provide scientific reference for improving the discharge standards of WWTP.
2023, 41(9): 201-209.
doi: 10.13205/j.hjgc.202309025
Abstract:
Hydrothermal treatment (HT) has been recognized as an environmental-friendly technology, which has been systematically summarized in terms of improving dewaterability, and recovering bio-energy and nutrients from sewage sludge. There is still a lack of systematic overview on the application of HT on sewage sludge harmlessness. Firstly, this paper summarized the effect of HT on the solid-liquid phase migration and chemical speciation transformation of heavy metals. That was, the HT significantly reduced the bioavailability and leachability of heavy metals in the solid phase, while the content and ecological risk of heavy metals in the liquid phase and bio-oil get increased. Secondly, the research progress of HT on the removal efficiency and degradation mechanism of pathogenic bacteria and toxic organic pollutants were summarized. That was, the HT could effectively remove antibiotics and resistance genes, persistent organic pollutants, pathogenic bacteria, and microplastics. However, among them, the biotoxicity of the degradation products of polychlorinated biphenyls (PCBs), polyfluoroalkyl substances (PFAS), and hydrothermal degradation products of microplastics (PE and PVC) were increased. Finally, in view of the current status of research, future research directions were proposed, including identifying the influence mechanism of organic/inorganic components in sludge on the transformation of toxic and harmful pollutants during HT, and evaluating the ecological risk of intermediate/final products of different toxic organic pollutants after HT.
Hydrothermal treatment (HT) has been recognized as an environmental-friendly technology, which has been systematically summarized in terms of improving dewaterability, and recovering bio-energy and nutrients from sewage sludge. There is still a lack of systematic overview on the application of HT on sewage sludge harmlessness. Firstly, this paper summarized the effect of HT on the solid-liquid phase migration and chemical speciation transformation of heavy metals. That was, the HT significantly reduced the bioavailability and leachability of heavy metals in the solid phase, while the content and ecological risk of heavy metals in the liquid phase and bio-oil get increased. Secondly, the research progress of HT on the removal efficiency and degradation mechanism of pathogenic bacteria and toxic organic pollutants were summarized. That was, the HT could effectively remove antibiotics and resistance genes, persistent organic pollutants, pathogenic bacteria, and microplastics. However, among them, the biotoxicity of the degradation products of polychlorinated biphenyls (PCBs), polyfluoroalkyl substances (PFAS), and hydrothermal degradation products of microplastics (PE and PVC) were increased. Finally, in view of the current status of research, future research directions were proposed, including identifying the influence mechanism of organic/inorganic components in sludge on the transformation of toxic and harmful pollutants during HT, and evaluating the ecological risk of intermediate/final products of different toxic organic pollutants after HT.
2023, 41(9): 210-220.
doi: 10.13205/j.hjgc.202309026
Abstract:
Sludge resource utilization is an important measure in China to solve resource and environmental problems and reduce pollution and carbon. Recovering and recycling aluminum salt components in sludge is an effective way to promote the green development of wastewater treatment plants. This article introduced the material flow and reaction mechanism of aluminum coagulants; based on the analysis of the occurrence form of aluminum salts in sludge, the related technologies and research status of aluminum recovery in sludge were comprehensively reviewed, with the technical scheme of release-separation-reuse of aluminum salts as the core, and its impacts on phosphorus recovery were also discussed. A variety of separation technologies of aluminum salts, which aimed to overcome the obstacles of phosphorus and heavy metals co-dissolving under acidic condition, were emphatically analyzed, including sequential precipitation, ion exchange resin, liquid-liquid extraction, sulfide precipitation, Donnan membrane, and electrodialysis process. A joint recovery process for aluminum salts and phosphorus was constructed according to the above analysis. In view of the current situation and problems of aluminum salts recovery in sludge, potential research directions, including improving aluminum salts recovery efficiency, analyzing the full chain economic benefits, and evaluating the effectiveness of aluminum salts coagulant recycling were proposed, aiming to promote the construction of sewage and sludge treatment systems with higher resource utilization levels and better accordance with the circular economy context.
Sludge resource utilization is an important measure in China to solve resource and environmental problems and reduce pollution and carbon. Recovering and recycling aluminum salt components in sludge is an effective way to promote the green development of wastewater treatment plants. This article introduced the material flow and reaction mechanism of aluminum coagulants; based on the analysis of the occurrence form of aluminum salts in sludge, the related technologies and research status of aluminum recovery in sludge were comprehensively reviewed, with the technical scheme of release-separation-reuse of aluminum salts as the core, and its impacts on phosphorus recovery were also discussed. A variety of separation technologies of aluminum salts, which aimed to overcome the obstacles of phosphorus and heavy metals co-dissolving under acidic condition, were emphatically analyzed, including sequential precipitation, ion exchange resin, liquid-liquid extraction, sulfide precipitation, Donnan membrane, and electrodialysis process. A joint recovery process for aluminum salts and phosphorus was constructed according to the above analysis. In view of the current situation and problems of aluminum salts recovery in sludge, potential research directions, including improving aluminum salts recovery efficiency, analyzing the full chain economic benefits, and evaluating the effectiveness of aluminum salts coagulant recycling were proposed, aiming to promote the construction of sewage and sludge treatment systems with higher resource utilization levels and better accordance with the circular economy context.
