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2023 Vol. 41, No. 2
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2023, 41(2): 1-6,42.
doi: 10.13205/j.hjgc.202302001
Abstract:
In this research, the XDLVO (extended Derjaguin-Landau-Verwey-Overbeek) theory was employed to analyze the fouling status of nanofiltration (NF) membrane caused by hydrophilic and hydrophobic organic matters. Quantitative analysis was conducted on six types of hydrophilic and hydrophobic organic matters with different molecular weight ranges (less than 100 kDa, less than 50 kDa, and less than 3 kDa, respectively) and the interfacial free energy of NF membrane was analyzed, in a bid to figure out the performance of the membrane fouling. Furthermore, the corresponding relationship between flux decay and interfacial free energy was verified by the NF experiment. The results showed that the degree of membrane fouling caused by the above-mentioned six hydrophilic or hydrophobic organic matters with different molecular weights in this study was consistent with the XDLVO theoretical analysis, in which the hydrophobic ones with a molecular weight less than 100 kDa showed the slightest repulsive interaction against the membrane and led to the most serious fouling. Besides, the degree of NF membrane fouling by different organic matters was ordered in a descending way as follows:(hydrophobic, molecular weight less than 100 kDa)>(hydrophobic, molecular weight less than 50 kDa)>(hydrophobic, molecular weight less than 3 kDa)>(hydrophilic, molecular weight less than 3 kDa)>(hydrophilic, molecular weight less than 50 kDa)>(hydrophilic, molecular weight less than 100 kDa). The main contaminants on the membrane surface were polysaccharides, proteins and phencyclic olefins, the organic matter clogged the membrane pores in the early stages of filtration, resulting in a rapid decrease in the specific flux of the membrane, while the formation of a cake layer in the later stages of filtration slowed the decrease in the specific flux of the membrane.
In this research, the XDLVO (extended Derjaguin-Landau-Verwey-Overbeek) theory was employed to analyze the fouling status of nanofiltration (NF) membrane caused by hydrophilic and hydrophobic organic matters. Quantitative analysis was conducted on six types of hydrophilic and hydrophobic organic matters with different molecular weight ranges (less than 100 kDa, less than 50 kDa, and less than 3 kDa, respectively) and the interfacial free energy of NF membrane was analyzed, in a bid to figure out the performance of the membrane fouling. Furthermore, the corresponding relationship between flux decay and interfacial free energy was verified by the NF experiment. The results showed that the degree of membrane fouling caused by the above-mentioned six hydrophilic or hydrophobic organic matters with different molecular weights in this study was consistent with the XDLVO theoretical analysis, in which the hydrophobic ones with a molecular weight less than 100 kDa showed the slightest repulsive interaction against the membrane and led to the most serious fouling. Besides, the degree of NF membrane fouling by different organic matters was ordered in a descending way as follows:(hydrophobic, molecular weight less than 100 kDa)>(hydrophobic, molecular weight less than 50 kDa)>(hydrophobic, molecular weight less than 3 kDa)>(hydrophilic, molecular weight less than 3 kDa)>(hydrophilic, molecular weight less than 50 kDa)>(hydrophilic, molecular weight less than 100 kDa). The main contaminants on the membrane surface were polysaccharides, proteins and phencyclic olefins, the organic matter clogged the membrane pores in the early stages of filtration, resulting in a rapid decrease in the specific flux of the membrane, while the formation of a cake layer in the later stages of filtration slowed the decrease in the specific flux of the membrane.
ADSORPTION TREATMENT OF SIMULATIVE WASTEWATER CONTAINING CHROMIUM BY MODIFIED POROUS BLUECOKE POWDER
2023, 41(2): 7-15.
doi: 10.13205/j.hjgc.202302002
Abstract:
Using low-value blue coke as the raw material, modified porous bluecoke (MA-BC) was prepared by acid washing and microwave activation, and an experimental study on its adsorption treatment of simulated Cr(Ⅵ)-containing wastewater was carried out. The surface morphology and structure and functional groups of the bluecoke powder before and after the modification were compared and analyzed by BET, SEM, N2 adsorption-desorption test, and FT-IR. In the treatment of the simulated Cr(Ⅵ)-containing wastewater, the dosage of MA-BC, simulated wastewater pH, initial concentration of Cr(Ⅵ), and adsorption time were investigated respectively, and the thermodynamics and kinetics for the adsorption process of Cr(Ⅵ) were analyzed. The results showed that the specific surface area of activated bluecoke powder by acid washing and microwave heating increased to 160.69 m2/g, and the content of functional groups, -OH, C=C and -CH3 on the surface of MA-BC significantly increased. Under the optimal process condition that the initial concentration of Cr(Ⅵ) in the simulated wastewater was 100 mg/L, pH was 2, the MA-BC dosage was 2 g, the adsorption time was 210 min, and then the removal rate of Cr(Ⅵ) could reach 89.21%. The main adsorption process belonged to the chemical adsorption, which obeyed the pseudo-second-order kinetic equation and conformed to the Langmuir adsorption isotherm model. The theoretical adsorption capacity was 6.255 mg/g, which was consistent with the equilibrium adsorption capacity of the experiment. After 5 cycles of regeneration and adsorption, the removal rate of Cr(Ⅵ) in simulated wastewater absorbed by MA-BC remained 80% above.
Using low-value blue coke as the raw material, modified porous bluecoke (MA-BC) was prepared by acid washing and microwave activation, and an experimental study on its adsorption treatment of simulated Cr(Ⅵ)-containing wastewater was carried out. The surface morphology and structure and functional groups of the bluecoke powder before and after the modification were compared and analyzed by BET, SEM, N2 adsorption-desorption test, and FT-IR. In the treatment of the simulated Cr(Ⅵ)-containing wastewater, the dosage of MA-BC, simulated wastewater pH, initial concentration of Cr(Ⅵ), and adsorption time were investigated respectively, and the thermodynamics and kinetics for the adsorption process of Cr(Ⅵ) were analyzed. The results showed that the specific surface area of activated bluecoke powder by acid washing and microwave heating increased to 160.69 m2/g, and the content of functional groups, -OH, C=C and -CH3 on the surface of MA-BC significantly increased. Under the optimal process condition that the initial concentration of Cr(Ⅵ) in the simulated wastewater was 100 mg/L, pH was 2, the MA-BC dosage was 2 g, the adsorption time was 210 min, and then the removal rate of Cr(Ⅵ) could reach 89.21%. The main adsorption process belonged to the chemical adsorption, which obeyed the pseudo-second-order kinetic equation and conformed to the Langmuir adsorption isotherm model. The theoretical adsorption capacity was 6.255 mg/g, which was consistent with the equilibrium adsorption capacity of the experiment. After 5 cycles of regeneration and adsorption, the removal rate of Cr(Ⅵ) in simulated wastewater absorbed by MA-BC remained 80% above.
2023, 41(2): 16-23.
doi: 10.13205/j.hjgc.202302003
Abstract:
Taking Le'an River, a typical into-lake river of Poyang Lake as an example, the SWAT model was constructed. Based on the spatial variation characteristics of land use types in the watershed in 2020, the years of 2014 (normal year), 2015 (wet year) and 2011 (dry year) were selected as typical rainfall years to explore the influence of rainfall variation on nutrient pollutants production regulations. The results showed that the nutrients production load of the watershed showed a trend of wet year>normal year>dry year. The runoff along the main branch area downstream, and the TN and TP in the Dexing-Poyang Wannian section in the middle and downstream were more sensitive to the increase of precipitation. The spatial differences in the response in runoff volume to rainfall reduction in the watershed were not significant. The TN and TP in the Wuyuan-Dexing section responded to the decrease in rainfall to a high degree while the response to the decrease in rainfall in the Poyang-Wannian section was lower. The research results will provide scientific reference for the development of targeted pollution control measures in the watershed and further reduce the nutrient load into Poyang Lake effectively.
Taking Le'an River, a typical into-lake river of Poyang Lake as an example, the SWAT model was constructed. Based on the spatial variation characteristics of land use types in the watershed in 2020, the years of 2014 (normal year), 2015 (wet year) and 2011 (dry year) were selected as typical rainfall years to explore the influence of rainfall variation on nutrient pollutants production regulations. The results showed that the nutrients production load of the watershed showed a trend of wet year>normal year>dry year. The runoff along the main branch area downstream, and the TN and TP in the Dexing-Poyang Wannian section in the middle and downstream were more sensitive to the increase of precipitation. The spatial differences in the response in runoff volume to rainfall reduction in the watershed were not significant. The TN and TP in the Wuyuan-Dexing section responded to the decrease in rainfall to a high degree while the response to the decrease in rainfall in the Poyang-Wannian section was lower. The research results will provide scientific reference for the development of targeted pollution control measures in the watershed and further reduce the nutrient load into Poyang Lake effectively.
2023, 41(2): 24-29.
doi: 10.13205/j.hjgc.202302004
Abstract:
To solve the problem of high treatment cost of cyanobacterial sludge and fewer recycling procedures, a collaborative process of the filtrate and municipal surplus sludge was explored based on deep dewatering by thermal press filtration. The thermal press filtrate from the cyanobacterial sludge was reused to dilute the municipal surplus sludge for its deep dewatering. The dewatering performance of the thermal press filtrate on the municipal surplus sludge at various pH conditions, and the resulting pollutants' concentrations in the municipal sludge filtrate were investigated. The result showed that the ferric ions in the filtrate of the cyanobacterial sludge by thermal press filtration were conducive to the deep dewatering of municipal surplus sludge. The optimal condition for the thermal press filtrate to be reused and diluted for municipal surplus sludge dewatering was to adjust the pH value to 7 with calcium oxide, and then mixed it with the municipal surplus sludge. In this way, the dosage of chemicals for the collaborative treatment process could be reduced by 68.1%. Compared with the conventional municipal sludge treatment process, the filtrate volume was reduced by 45% and the total unit cost was decreased by 16.6%. The collaborative treatment process would promote the economic treatment of cyanobacterial sludge and expand the recycling methods.
To solve the problem of high treatment cost of cyanobacterial sludge and fewer recycling procedures, a collaborative process of the filtrate and municipal surplus sludge was explored based on deep dewatering by thermal press filtration. The thermal press filtrate from the cyanobacterial sludge was reused to dilute the municipal surplus sludge for its deep dewatering. The dewatering performance of the thermal press filtrate on the municipal surplus sludge at various pH conditions, and the resulting pollutants' concentrations in the municipal sludge filtrate were investigated. The result showed that the ferric ions in the filtrate of the cyanobacterial sludge by thermal press filtration were conducive to the deep dewatering of municipal surplus sludge. The optimal condition for the thermal press filtrate to be reused and diluted for municipal surplus sludge dewatering was to adjust the pH value to 7 with calcium oxide, and then mixed it with the municipal surplus sludge. In this way, the dosage of chemicals for the collaborative treatment process could be reduced by 68.1%. Compared with the conventional municipal sludge treatment process, the filtrate volume was reduced by 45% and the total unit cost was decreased by 16.6%. The collaborative treatment process would promote the economic treatment of cyanobacterial sludge and expand the recycling methods.
2023, 41(2): 30-36,52.
doi: 10.13205/j.hjgc.202302005
Abstract:
Based on the study of water environmental pollution in the Shaying River basin, the heavy metal pollution characteristics of water samples in different water periods and in different reaches of the main river and the tributaries were analyzed by using the calculation methods of different pollution evaluation indexes, and the control factors of water environmental pollution and the influencing laws on their migration were discussed separately, to provide a theoretical basis for the prevention and control of water environmental pollution in Shaying River basin. The results showed that the overall pollution of The Shaying River basin was slightly polluted by Mn and Mo in the dry season. The overall pollution of the Shaying River basin was controlled by the pollution of the upper tributary Yinghe River and the tributary Beiru River. The main controlling factors of pollution of the Yinghe River and the Beiru River were Mn and Mo. The main source of pollution was the discharge of mineral and industrial sewage, which migrated and transformed downstream from the upper reaches to the lower reaches, presenting a mild pollution level of the whole basin. And the polution level was mainly affected by pH value, dissolved oxygen (DO) and temperature (T) value.
Based on the study of water environmental pollution in the Shaying River basin, the heavy metal pollution characteristics of water samples in different water periods and in different reaches of the main river and the tributaries were analyzed by using the calculation methods of different pollution evaluation indexes, and the control factors of water environmental pollution and the influencing laws on their migration were discussed separately, to provide a theoretical basis for the prevention and control of water environmental pollution in Shaying River basin. The results showed that the overall pollution of The Shaying River basin was slightly polluted by Mn and Mo in the dry season. The overall pollution of the Shaying River basin was controlled by the pollution of the upper tributary Yinghe River and the tributary Beiru River. The main controlling factors of pollution of the Yinghe River and the Beiru River were Mn and Mo. The main source of pollution was the discharge of mineral and industrial sewage, which migrated and transformed downstream from the upper reaches to the lower reaches, presenting a mild pollution level of the whole basin. And the polution level was mainly affected by pH value, dissolved oxygen (DO) and temperature (T) value.
2023, 41(2): 37-42.
doi: 10.13205/j.hjgc.202302006
Abstract:
Experiments were carried out by using self-designed spray bed electro-deposition devices to treat zinc-containing wastewater under different conditions including pH value, current intensity, zinc ions concentration and bubbling nitrogen. The effect of the spray bed electro-deposition system on treatment of zinc-containing wastewater was investigated and the parameters were optimized. The results showed that the optimized condition was as follows:the particle size of electrode of 1.8 mm, zinc ions concentration of 1000 mg/L, wastewater pH value of 4.5, current value of 15 A and bubbling nitrogen of 600 L/h, then the removal rate of zinc ions was up to 49.44% and the current efficiency was 41.63%. On this basis, the dynamic model of single metal ion electro-deposition was established by dynamic simulation analysis, which proved the reliability of the measured data and the accuracy of the experimental results.
Experiments were carried out by using self-designed spray bed electro-deposition devices to treat zinc-containing wastewater under different conditions including pH value, current intensity, zinc ions concentration and bubbling nitrogen. The effect of the spray bed electro-deposition system on treatment of zinc-containing wastewater was investigated and the parameters were optimized. The results showed that the optimized condition was as follows:the particle size of electrode of 1.8 mm, zinc ions concentration of 1000 mg/L, wastewater pH value of 4.5, current value of 15 A and bubbling nitrogen of 600 L/h, then the removal rate of zinc ions was up to 49.44% and the current efficiency was 41.63%. On this basis, the dynamic model of single metal ion electro-deposition was established by dynamic simulation analysis, which proved the reliability of the measured data and the accuracy of the experimental results.
2023, 41(2): 43-52.
doi: 10.13205/j.hjgc.202302007
Abstract:
The emission of greenhouse gases in the Three Gorges Reservoir area has attracted much attention in recent years, but the current research lacks the analysis of the impact of biochemical processes during algal blooms on CO2 production and sinks in water body. So this research took the mainstream, Wanzhou Section of Three Gorges Reservoir, and a typical tributary, Pengxi River as the objects to carry out an investigation. The result showed that there were significant spatial differences in the correlation between the main stream and tributary CO2 concentration and flux, environmental factors and biogenic substances.The concentration of CO2 in tributary water was significantly negatively correlated with water temperature, pH and DO, and significantly positively correlated with DOC and DTP. There was a significant negative correlation between CO2 flux at the water-air interface and water temperature, and a significant positive correlation with DTP and CO2 concentration. The concentration of CO2 in the main stream water was negatively correlated with pH, and positively correlated with DIC, DOC, NH+4-N. The CO2 flux at the water-air interface was significantly positively correlated with the concentrations of NH+4-N and CO2. The changes of CO2 fluxes at the water-air interface at Gaoyang, Huangshi, and Wanzhou were basically consistent with the changes of CO2 concentrations in their respective surface waters. Algae fixes CO2 as they grow, boosting carbon sinks. The process of algal bloom will cause regional hypoxia or even anaerobicity. The reason was that algae accumulate, accumulate, and die on the water surface, which consumed the dissolved oxygen in the water and provided a decomposition environment for microorganisms in the sediment. The organic matter that sank into the sediments provided a carbon source for microorganisms, and then mineralization occursed to generate greenhouse gases such as CO2.
The emission of greenhouse gases in the Three Gorges Reservoir area has attracted much attention in recent years, but the current research lacks the analysis of the impact of biochemical processes during algal blooms on CO2 production and sinks in water body. So this research took the mainstream, Wanzhou Section of Three Gorges Reservoir, and a typical tributary, Pengxi River as the objects to carry out an investigation. The result showed that there were significant spatial differences in the correlation between the main stream and tributary CO2 concentration and flux, environmental factors and biogenic substances.The concentration of CO2 in tributary water was significantly negatively correlated with water temperature, pH and DO, and significantly positively correlated with DOC and DTP. There was a significant negative correlation between CO2 flux at the water-air interface and water temperature, and a significant positive correlation with DTP and CO2 concentration. The concentration of CO2 in the main stream water was negatively correlated with pH, and positively correlated with DIC, DOC, NH+4-N. The CO2 flux at the water-air interface was significantly positively correlated with the concentrations of NH+4-N and CO2. The changes of CO2 fluxes at the water-air interface at Gaoyang, Huangshi, and Wanzhou were basically consistent with the changes of CO2 concentrations in their respective surface waters. Algae fixes CO2 as they grow, boosting carbon sinks. The process of algal bloom will cause regional hypoxia or even anaerobicity. The reason was that algae accumulate, accumulate, and die on the water surface, which consumed the dissolved oxygen in the water and provided a decomposition environment for microorganisms in the sediment. The organic matter that sank into the sediments provided a carbon source for microorganisms, and then mineralization occursed to generate greenhouse gases such as CO2.
2023, 41(2): 53-59,65.
doi: 10.13205/j.hjgc.202302008
Abstract:
The anaerobic fermentation process of piggery wastewater at different initial alkalinity levels (3503, 5500, 7500 mg/L, as CaCO3) and temperature (20, 35, 50℃) was studied by sequential batch experiment. The characteristics of its influences on pH, volatile fatty acids, gas production, biogas slurry nutrients, heavy metal content, antibiotics and resistance genes were investigated. The results revealed that the initial alkalinity adjustment could delay the initiation of the hydrolysis and acidification stage of anaerobic fermentation, strengthen the process of acid production and increase total acid production. The highest pH maintenance ability was presented with the operation of the highest level of alkalinity. The initial alkalinity regulation was suitable for anaerobic fermentation at moderate and high temperature with the purpose of producing acid. 35℃ and 50℃ was conducive to releasing nutrients from fermentation substrates, and the highest nutrient concentration was (1365.14±124.38)~(1471.71±135.29) mg/L at 50℃. Anaerobic fermentation at 50℃ was more conducive to the reduction of soluble heavy metals (Cu,Zn) in biogas slurry, and the reduction ratios were (81.53±9.51)~(86.04±7.72)% and (96.48±8.73)~(97.81±10.29)%, respectively. Anaerobic fermentation could reduce the concentrations of antibiotics (oxytetracycline and norfloxacin) in biogas slurry, and the highest reduction rate was (14.61±1.39)~(56.26±5.24)% and (23.83±3.21)~(85.84±17.35)% at 50℃ compared with 20℃ and 35℃, respectively. The relative abundance of resistance genes were decreased at 50℃ and appropriate initial alkalinity regulation effectively. The results of this research could provide a reference for the optimization of the anaerobic fermentation process of livestock wastewater.
The anaerobic fermentation process of piggery wastewater at different initial alkalinity levels (3503, 5500, 7500 mg/L, as CaCO3) and temperature (20, 35, 50℃) was studied by sequential batch experiment. The characteristics of its influences on pH, volatile fatty acids, gas production, biogas slurry nutrients, heavy metal content, antibiotics and resistance genes were investigated. The results revealed that the initial alkalinity adjustment could delay the initiation of the hydrolysis and acidification stage of anaerobic fermentation, strengthen the process of acid production and increase total acid production. The highest pH maintenance ability was presented with the operation of the highest level of alkalinity. The initial alkalinity regulation was suitable for anaerobic fermentation at moderate and high temperature with the purpose of producing acid. 35℃ and 50℃ was conducive to releasing nutrients from fermentation substrates, and the highest nutrient concentration was (1365.14±124.38)~(1471.71±135.29) mg/L at 50℃. Anaerobic fermentation at 50℃ was more conducive to the reduction of soluble heavy metals (Cu,Zn) in biogas slurry, and the reduction ratios were (81.53±9.51)~(86.04±7.72)% and (96.48±8.73)~(97.81±10.29)%, respectively. Anaerobic fermentation could reduce the concentrations of antibiotics (oxytetracycline and norfloxacin) in biogas slurry, and the highest reduction rate was (14.61±1.39)~(56.26±5.24)% and (23.83±3.21)~(85.84±17.35)% at 50℃ compared with 20℃ and 35℃, respectively. The relative abundance of resistance genes were decreased at 50℃ and appropriate initial alkalinity regulation effectively. The results of this research could provide a reference for the optimization of the anaerobic fermentation process of livestock wastewater.
2023, 41(2): 60-65.
doi: 10.13205/j.hjgc.202302009
Abstract:
In order to investigate the effect of dissolved oxygen on the dissolution of sponge iron in the biological sponge iron system, sponge iron was involved in the activated sludge to form the biological sponge iron system. By simulating the corrosion state of sponge iron in the actual reactor and measuring the TFe content in the biological sponge iron system, the effect of dissolved oxygen on the dissolution of sponge iron was studied. By making sponge iron into a working electrode and intervening into the activated sludge, the effect of dissolved oxygen on the corrosion rate and polarization resistance of sponge iron in the biological sponge iron system was studied by AUTOLAB electrochemical workstation. The results showed that in the biological sponge iron system, TFe dissolution of sponge iron was positively correlated with the DO concentration of the reaction system, and the effect became more and more obvious with the prolonging of running time. With the increase of dissolved oxygen in activated sludge mixed solution, the corrosion potential moved negatively, the corrosion current moved positively, the corrosion tendency increased, and the corrosion effect became stronger. Through the polarization curve and parameters analysis, the polarization resistance of sponge iron under different dissolved oxygen followed the order of (6.5±0.5) mg/L<(3.5±0.2) mg/L<(0.5±0.2) mg/L. Under anoxic condition, the corrosion resistance was stronger, and dissolved oxygen could reduce the polarization resistance and promote the corrosion of sponge iron filler.
In order to investigate the effect of dissolved oxygen on the dissolution of sponge iron in the biological sponge iron system, sponge iron was involved in the activated sludge to form the biological sponge iron system. By simulating the corrosion state of sponge iron in the actual reactor and measuring the TFe content in the biological sponge iron system, the effect of dissolved oxygen on the dissolution of sponge iron was studied. By making sponge iron into a working electrode and intervening into the activated sludge, the effect of dissolved oxygen on the corrosion rate and polarization resistance of sponge iron in the biological sponge iron system was studied by AUTOLAB electrochemical workstation. The results showed that in the biological sponge iron system, TFe dissolution of sponge iron was positively correlated with the DO concentration of the reaction system, and the effect became more and more obvious with the prolonging of running time. With the increase of dissolved oxygen in activated sludge mixed solution, the corrosion potential moved negatively, the corrosion current moved positively, the corrosion tendency increased, and the corrosion effect became stronger. Through the polarization curve and parameters analysis, the polarization resistance of sponge iron under different dissolved oxygen followed the order of (6.5±0.5) mg/L<(3.5±0.2) mg/L<(0.5±0.2) mg/L. Under anoxic condition, the corrosion resistance was stronger, and dissolved oxygen could reduce the polarization resistance and promote the corrosion of sponge iron filler.
2023, 41(2): 66-72,81.
doi: 10.13205/j.hjgc.202302010
Abstract:
Engineering practice showed that the adsorption performance of Y molecular sieve was greatly reduced under high humidity environment. In this paper, Y@mesoSiO2 was obtained by pretreating polydiallyl dimethylammonium chloride (PDDA) along with the growth of mesoSiO2 shell on Y molecular sieve. Polydimethylsiloxane (PDMS) was further grafted onto mesoSiO2 shell to prepare Y@mesoSiO2-S via chemical vapor deposition method. The morphology and structure of the modified Y molecular sieve were analyzed by SEM, TEM, XRD, XPS, surface area and pore size analyzer. Besides, the adsorption of water and toluene was evaluated by static and dynamic adsorption experiments. The results showed that the mesoSiO2 shell successfully grew on the outer surface of Y molecular sieve and PDMS was successfully grafted onto the Y@mesoSiO2 shell. Compared with Y molecular sieve, the BET specific surface area (SBET) of Y@mesoSiO2-S increased by 2%; meanwhile, the water contact angle was enhanced significantly, causing the static water absorption decreased from 298 mg/g to 79 mg/g, and the dynamic water absorption decreased from 245 mg/g to 76 mg/g. The saturated adsorption capacity of toluene on Y@mesoSiO2-S and Y molecular sieve were 167.2 mg/g and 2.6 mg/g at an RH of 80%, respectively, which decreased by 6.7% and 98.3% relatively, compared with an RH of 20%. When compared with Y-S without mesoSiO2 shell, Y@mesoSiO2-S presented increased SBET and the saturated adsorption capacity of toluene with 46% and 51% at an RH of 80%, respectively. This indicated that mesoSiO2 shell was introduced between Y molecular sieve and PDMS, which could avoid clogging of porosity caused by direct grafting PDMS on the surface of Y molecular sieve. Furthermore, this strategy could improve the hydrophobic property of Y molecular sieve, resulting in enhanced adsorption performance on toluene under high humidity.
Engineering practice showed that the adsorption performance of Y molecular sieve was greatly reduced under high humidity environment. In this paper, Y@mesoSiO2 was obtained by pretreating polydiallyl dimethylammonium chloride (PDDA) along with the growth of mesoSiO2 shell on Y molecular sieve. Polydimethylsiloxane (PDMS) was further grafted onto mesoSiO2 shell to prepare Y@mesoSiO2-S via chemical vapor deposition method. The morphology and structure of the modified Y molecular sieve were analyzed by SEM, TEM, XRD, XPS, surface area and pore size analyzer. Besides, the adsorption of water and toluene was evaluated by static and dynamic adsorption experiments. The results showed that the mesoSiO2 shell successfully grew on the outer surface of Y molecular sieve and PDMS was successfully grafted onto the Y@mesoSiO2 shell. Compared with Y molecular sieve, the BET specific surface area (SBET) of Y@mesoSiO2-S increased by 2%; meanwhile, the water contact angle was enhanced significantly, causing the static water absorption decreased from 298 mg/g to 79 mg/g, and the dynamic water absorption decreased from 245 mg/g to 76 mg/g. The saturated adsorption capacity of toluene on Y@mesoSiO2-S and Y molecular sieve were 167.2 mg/g and 2.6 mg/g at an RH of 80%, respectively, which decreased by 6.7% and 98.3% relatively, compared with an RH of 20%. When compared with Y-S without mesoSiO2 shell, Y@mesoSiO2-S presented increased SBET and the saturated adsorption capacity of toluene with 46% and 51% at an RH of 80%, respectively. This indicated that mesoSiO2 shell was introduced between Y molecular sieve and PDMS, which could avoid clogging of porosity caused by direct grafting PDMS on the surface of Y molecular sieve. Furthermore, this strategy could improve the hydrophobic property of Y molecular sieve, resulting in enhanced adsorption performance on toluene under high humidity.
2023, 41(2): 73-81.
doi: 10.13205/j.hjgc.202302011
Abstract:
In order to accurately measure the air pollution in Fujian province at the regional (county, city) scale, the APEI index was constructed. Based on high-resolution air pollution data set and nighttime light data, the spatio-temporal variation characteristics of air pollution degree and its influencing factors in 78 counties and cities of Fujian province from 2013 to 2018 were analyzed. Results showed that:1) air pollution degree in the counties and cities in the north of the center of Fujian province is low, and air pollution degree in the coastal counties and cities in the east of Fujian province is serious. In the past 6 years, 78.21% of counties and cities in Fujian province reduced their air pollution; 2) the serious air pollution in the eastern coastal areas of the province is mainly manifested in two kinds of air pollutants, NO2 and PM10, both exceeding the average level of the province; 3) from the time series variation trend of atmospheric pollutants, O3 shows a U-shaped change; PM2.5 and PM10 have similar changes, decreasing year by year from 2014 to 2018 by 23.15% and 12.21% respectively. CO changes in an inverted U shape. SO2 and NO2 decreased, respectively; 4) the six kinds of air pollutants showed obvious seasonal fluctuation; 5) spatio-temporal heterogeneity of the impact of night light on APEI was analyzed by using spatiotemporal weighted regression (STWR) model. It was found that the negative influence area continued to expand from 2014 to 2018. The regression coefficients of 34 counties and cities were all positive in five years, indicating that these counties and cities are prone to air pollution caused by human activities; 6) air quality index (AQI) and air quality composite index (AQCI) are used to evaluate the ranking of the comprehensive air pollution degree in Fujian province in the past six years, and it was found that APEI index could better tell the relationship between the real concentration.
In order to accurately measure the air pollution in Fujian province at the regional (county, city) scale, the APEI index was constructed. Based on high-resolution air pollution data set and nighttime light data, the spatio-temporal variation characteristics of air pollution degree and its influencing factors in 78 counties and cities of Fujian province from 2013 to 2018 were analyzed. Results showed that:1) air pollution degree in the counties and cities in the north of the center of Fujian province is low, and air pollution degree in the coastal counties and cities in the east of Fujian province is serious. In the past 6 years, 78.21% of counties and cities in Fujian province reduced their air pollution; 2) the serious air pollution in the eastern coastal areas of the province is mainly manifested in two kinds of air pollutants, NO2 and PM10, both exceeding the average level of the province; 3) from the time series variation trend of atmospheric pollutants, O3 shows a U-shaped change; PM2.5 and PM10 have similar changes, decreasing year by year from 2014 to 2018 by 23.15% and 12.21% respectively. CO changes in an inverted U shape. SO2 and NO2 decreased, respectively; 4) the six kinds of air pollutants showed obvious seasonal fluctuation; 5) spatio-temporal heterogeneity of the impact of night light on APEI was analyzed by using spatiotemporal weighted regression (STWR) model. It was found that the negative influence area continued to expand from 2014 to 2018. The regression coefficients of 34 counties and cities were all positive in five years, indicating that these counties and cities are prone to air pollution caused by human activities; 6) air quality index (AQI) and air quality composite index (AQCI) are used to evaluate the ranking of the comprehensive air pollution degree in Fujian province in the past six years, and it was found that APEI index could better tell the relationship between the real concentration.
2023, 41(2): 82-90.
doi: 10.13205/j.hjgc.202302012
Abstract:
An investigation on the spatial and temporal distribution characteristics and correlation analysis with meteorological elements were conducted on the main atmospheric pollutants (PM2.5, PM10, SO2, CO, NO2 and O3) in Wuhan from 2017 to 2020, to understand the level of atmospheric pollution in each district of Wuhan. The results were as follows:The overall achievement rate of ambient air quality in Wuhan over the past four years was 72.98%. The pollution of PM2.5, PM10, SO2, CO and NO2 was more serious in winter, and less in summer; the pollution of O3 was more in summer, and less in winter. PM2.5 and PM10 were the exceeding pollutants among the atmospheric pollutants, but the annual average mass concentrations were on a decreasing trend, while O3 was the only air pollutant whose annual average mass concentration was on the rise, so particulate matters and ozone pollution should be paid on more attention in the future. PM2.5, PM10, SO2, CO and NO2 were more concentrated in Wuchang District, Caidian District, Qingshan District, Jianghan District, Jiangan District, and O3 were concentrated in Huangpi District, Xinzhou District and Jiangxia District. PM2.5, PM10, SO2, CO and NO2 were significantly positively correlated with each other, while O3 and these five atmospheric pollutants were significantly negatively correlated. Mean temperature was significantly negatively correlated with PM2.5, PM10, SO2, CO and NO2, and significantly and strongly positively correlated with O3. Sunshine duration was significantly negatively correlated with all six pollutants. Mean wind speed was significantly negatively correlated with PM2.5, PM10, SO2, CO and NO2, and significantly positively correlated with O3. Relative humidity had the least effect on air pollutants and was only weakly correlated with SO2. The main meteorological elements affecting air pollutants in Wuhan were average temperature and sunshine duration.
An investigation on the spatial and temporal distribution characteristics and correlation analysis with meteorological elements were conducted on the main atmospheric pollutants (PM2.5, PM10, SO2, CO, NO2 and O3) in Wuhan from 2017 to 2020, to understand the level of atmospheric pollution in each district of Wuhan. The results were as follows:The overall achievement rate of ambient air quality in Wuhan over the past four years was 72.98%. The pollution of PM2.5, PM10, SO2, CO and NO2 was more serious in winter, and less in summer; the pollution of O3 was more in summer, and less in winter. PM2.5 and PM10 were the exceeding pollutants among the atmospheric pollutants, but the annual average mass concentrations were on a decreasing trend, while O3 was the only air pollutant whose annual average mass concentration was on the rise, so particulate matters and ozone pollution should be paid on more attention in the future. PM2.5, PM10, SO2, CO and NO2 were more concentrated in Wuchang District, Caidian District, Qingshan District, Jianghan District, Jiangan District, and O3 were concentrated in Huangpi District, Xinzhou District and Jiangxia District. PM2.5, PM10, SO2, CO and NO2 were significantly positively correlated with each other, while O3 and these five atmospheric pollutants were significantly negatively correlated. Mean temperature was significantly negatively correlated with PM2.5, PM10, SO2, CO and NO2, and significantly and strongly positively correlated with O3. Sunshine duration was significantly negatively correlated with all six pollutants. Mean wind speed was significantly negatively correlated with PM2.5, PM10, SO2, CO and NO2, and significantly positively correlated with O3. Relative humidity had the least effect on air pollutants and was only weakly correlated with SO2. The main meteorological elements affecting air pollutants in Wuhan were average temperature and sunshine duration.
2023, 41(2): 91-97.
doi: 10.13205/j.hjgc.202302013
Abstract:
Co-digestion of sludge and food waste can improve the stabilization of sludge. To enhance the co-digestion of sludge and food waste, the operation strategy of high temperature pretreatment and medium temperature anaerobic digestion was put forward. Moreover, the mechanism of the co-digestion system was discussed from the macro and micro levels, in order to provide technical support for the application of the strategy in practical engineering. Results showed that the operation strategy can not only improve the hydrolysis but also enhance the co-digestion effect. The ratio of SCOD/TCOD increased from 33.9% to 65% after one-day high temperature pretreatment of sludge and food waste. Methane production rate and organic removal rate of this study achieved 0.54 L/g and 78.8% (SRT=20 d), 0.76 L/g and 56.6% (SRT=15 d), higher than the actual project of high temperature (150~170℃) and high pressure (1 MPa) for pretreatment. Illumina MiSeq sequencing revealed that hydrolytic/acidogenic bacteria, such as Porphyromonadaceae, Draconibacteriaceae, Eubacterium and Romboutsia, were enriched in the co-digestion system after high temperature pretreatment. The bacteria promoted hydrolysis/acidification, and made sure methanogens have enough substrate to produce methane. Therefore, the gas production from the co-digestion of sludge and food waste was strengthened.
Co-digestion of sludge and food waste can improve the stabilization of sludge. To enhance the co-digestion of sludge and food waste, the operation strategy of high temperature pretreatment and medium temperature anaerobic digestion was put forward. Moreover, the mechanism of the co-digestion system was discussed from the macro and micro levels, in order to provide technical support for the application of the strategy in practical engineering. Results showed that the operation strategy can not only improve the hydrolysis but also enhance the co-digestion effect. The ratio of SCOD/TCOD increased from 33.9% to 65% after one-day high temperature pretreatment of sludge and food waste. Methane production rate and organic removal rate of this study achieved 0.54 L/g and 78.8% (SRT=20 d), 0.76 L/g and 56.6% (SRT=15 d), higher than the actual project of high temperature (150~170℃) and high pressure (1 MPa) for pretreatment. Illumina MiSeq sequencing revealed that hydrolytic/acidogenic bacteria, such as Porphyromonadaceae, Draconibacteriaceae, Eubacterium and Romboutsia, were enriched in the co-digestion system after high temperature pretreatment. The bacteria promoted hydrolysis/acidification, and made sure methanogens have enough substrate to produce methane. Therefore, the gas production from the co-digestion of sludge and food waste was strengthened.
2023, 41(2): 98-105.
doi: 10.13205/j.hjgc.202302014
Abstract:
In response to the lack of systematic environmental risk assessment of construction waste in China and the neglection of regional environmental chemical background values, the enrichment factor method, combined with geochemical background values, selecting four factors including environmental chemical background, regional categories, urban cluster development, elemental characteristics and four major urban clusters, including Beijing-Tianjin-Hebei, Huang-Huai-Huai River, Yangtze River Delta and Chang-Zhu-Tan, as the examples, five types of construction waste, the environmental pollution risk analysis was carried out on five types of construction waste and eight heavy metal elements. The results showed that:1) the pollution of heavy metal elements in construction waste was closely related to the development process of urban agglomerations; 2)the enrichment of different heavy metal elements was regional and influenced by the geochemical background values; 3) the introduction of heavy metals in the production process of construction materials had a direct impact on the total content of heavy metal elements in construction waste.
In response to the lack of systematic environmental risk assessment of construction waste in China and the neglection of regional environmental chemical background values, the enrichment factor method, combined with geochemical background values, selecting four factors including environmental chemical background, regional categories, urban cluster development, elemental characteristics and four major urban clusters, including Beijing-Tianjin-Hebei, Huang-Huai-Huai River, Yangtze River Delta and Chang-Zhu-Tan, as the examples, five types of construction waste, the environmental pollution risk analysis was carried out on five types of construction waste and eight heavy metal elements. The results showed that:1) the pollution of heavy metal elements in construction waste was closely related to the development process of urban agglomerations; 2)the enrichment of different heavy metal elements was regional and influenced by the geochemical background values; 3) the introduction of heavy metals in the production process of construction materials had a direct impact on the total content of heavy metal elements in construction waste.
2023, 41(2): 106-112,180.
doi: 10.13205/j.hjgc.202302015
Abstract:
Aiming at the problems of poor toughness and high brittleness of the final shape caused by water loss during the solidification of heavy metal contaminated soil by geopolymer, the feasibility of adding coconut fiber to the polymer soil solidified body in the ash base to alleviate its water loss shrinkage/cracking was explored. By simulating the changing trend of soil surface drying and cracking under the condition of frequent rain in alternate spring and summer and continuous high temperature in summer, the mechanical strengthening effect of fibers was explored by comparing the shrinkage and cracking of solidified blocks with or without heavy metal pollution. The results showed that the water loss rate of soil eroded by heavy metals was 9.0% higher than that of undisturbed soil, the cracking factor increased by 12.9%, and the shrinkage rate increased by 34.6% compared with the undisturbed soil in the 25-day sample. The cracking resistance of soil cured by geopolymer was improved, and the cracking factor of geopolymer cured blocks optimized by adding fiber in continuous drying test was further reduced, the shrinkage rate decreased by 71.3% and the cracking factor was only 4.9% to 5.1% of the undisturbed soil, and the minimum cracking factor was 0.0015 after four cycles of drying and wetting. Geopolymer-coconut fiber composite ameliorated the heavy metal contaminated soil and had a good cracking resistance effect.
Aiming at the problems of poor toughness and high brittleness of the final shape caused by water loss during the solidification of heavy metal contaminated soil by geopolymer, the feasibility of adding coconut fiber to the polymer soil solidified body in the ash base to alleviate its water loss shrinkage/cracking was explored. By simulating the changing trend of soil surface drying and cracking under the condition of frequent rain in alternate spring and summer and continuous high temperature in summer, the mechanical strengthening effect of fibers was explored by comparing the shrinkage and cracking of solidified blocks with or without heavy metal pollution. The results showed that the water loss rate of soil eroded by heavy metals was 9.0% higher than that of undisturbed soil, the cracking factor increased by 12.9%, and the shrinkage rate increased by 34.6% compared with the undisturbed soil in the 25-day sample. The cracking resistance of soil cured by geopolymer was improved, and the cracking factor of geopolymer cured blocks optimized by adding fiber in continuous drying test was further reduced, the shrinkage rate decreased by 71.3% and the cracking factor was only 4.9% to 5.1% of the undisturbed soil, and the minimum cracking factor was 0.0015 after four cycles of drying and wetting. Geopolymer-coconut fiber composite ameliorated the heavy metal contaminated soil and had a good cracking resistance effect.
2023, 41(2): 113-121,139.
doi: 10.13205/j.hjgc.202302016
Abstract:
Biochar, modified through acidification, alkalization or organification method, has been widely applied as an adsorbent for heavy metal immobilization. However, there is still a lack of information about the modification methods for improving the adsorption ability of biochar made from different raw materials. In addition, as a soil amendment, the influences and mechanisms of modified biochar in improving soil physico-chemical properties and stabilizing soil Pb and Cd also need further exploration. In this study, rice straw, sawdust and coconut shell were selected as the raw materials for the preparation of biochar. After modification by nitric acid and potassium permanganate, the surface characteristics of modified biochar such as specific surface area, pore structure and surface functional groups were measured. After then, the modified biochar was added into the tested soil (1000 mg/kg Pb, 10 mg/kg Cd) with a mass ratio of 2.5%, 5% and 10% respectively for 6 months of indoor immobilization test. Soil physico-chemical properties, speciation distribution of soil Pb and Cd and the relevant immobilization efficiency were measured at the end of the experiment. The results showed that, after modification, the specific surface area, micropore and oxygen-containing functional groups of different biochar were increased to varying degrees, which effectively enhanced the adsorption ability of biochar, especially for the modified coconut shell biochar. When the dosage of modified biochar was larger than 5%, the soil cation exchange capacity and organic matter content were observed increased by 15.89 g/kg and 5.28 cmol/kg respectively, which improved the fixation of soil nutrients and heavy metals. The modified biochar-soil system mainly promoted the transformation of soil available Pb and Cd to their potential activated and residual forms through ion exchange, complexation reaction and co-precipitation reaction. The degree of transformation was positively correlated with the immobilization time and dosage of modified biochar. Compared with Cd2+, Pb2+ in soil could be preferentially adsorbed and gradually reached adsorption equilibrium within 2 months due to the effect of competitive adsorption. The immobilization effect of modified coconut shell biochar on soil Pb and Cd was optimal with a dosage of 10%, and the highest immobilization rate was found as 59.72% and 36.37% respectively. In addition, continuous increases of soil cation exchange capacity and organic matter content were observed during the experiment, which might be caused by the "ageing effect" of biochar. Influenced by such effect, the bioavailability of Pb and Cd in soil kept decreasing and no secondary release of Pb2+ and Cd2+ were detected. In conclusion, the addition of modified biochar can improve soil structure, enhance soil fertility, and effectively stabilize soil Pb and Cd over a long time, and could be used in remediation of heavy metal contaminated soil.
Biochar, modified through acidification, alkalization or organification method, has been widely applied as an adsorbent for heavy metal immobilization. However, there is still a lack of information about the modification methods for improving the adsorption ability of biochar made from different raw materials. In addition, as a soil amendment, the influences and mechanisms of modified biochar in improving soil physico-chemical properties and stabilizing soil Pb and Cd also need further exploration. In this study, rice straw, sawdust and coconut shell were selected as the raw materials for the preparation of biochar. After modification by nitric acid and potassium permanganate, the surface characteristics of modified biochar such as specific surface area, pore structure and surface functional groups were measured. After then, the modified biochar was added into the tested soil (1000 mg/kg Pb, 10 mg/kg Cd) with a mass ratio of 2.5%, 5% and 10% respectively for 6 months of indoor immobilization test. Soil physico-chemical properties, speciation distribution of soil Pb and Cd and the relevant immobilization efficiency were measured at the end of the experiment. The results showed that, after modification, the specific surface area, micropore and oxygen-containing functional groups of different biochar were increased to varying degrees, which effectively enhanced the adsorption ability of biochar, especially for the modified coconut shell biochar. When the dosage of modified biochar was larger than 5%, the soil cation exchange capacity and organic matter content were observed increased by 15.89 g/kg and 5.28 cmol/kg respectively, which improved the fixation of soil nutrients and heavy metals. The modified biochar-soil system mainly promoted the transformation of soil available Pb and Cd to their potential activated and residual forms through ion exchange, complexation reaction and co-precipitation reaction. The degree of transformation was positively correlated with the immobilization time and dosage of modified biochar. Compared with Cd2+, Pb2+ in soil could be preferentially adsorbed and gradually reached adsorption equilibrium within 2 months due to the effect of competitive adsorption. The immobilization effect of modified coconut shell biochar on soil Pb and Cd was optimal with a dosage of 10%, and the highest immobilization rate was found as 59.72% and 36.37% respectively. In addition, continuous increases of soil cation exchange capacity and organic matter content were observed during the experiment, which might be caused by the "ageing effect" of biochar. Influenced by such effect, the bioavailability of Pb and Cd in soil kept decreasing and no secondary release of Pb2+ and Cd2+ were detected. In conclusion, the addition of modified biochar can improve soil structure, enhance soil fertility, and effectively stabilize soil Pb and Cd over a long time, and could be used in remediation of heavy metal contaminated soil.
2023, 41(2): 122-130.
doi: 10.13205/j.hjgc.202302017
Abstract:
To obtain a remediation method of Fenton pre-oxidation combined with bioremediation of oil-contaminated soil for efficient degradation of petroleum hydrocarbons (TPH), the characteristics of hydroxyl radical (·OH), NH+4-N concentration, DOC concentration, dehydrogenase and polyphenol oxidase activities and TPH removal with dosing different concentration of H2O2 by three batches were investigated in this study. The results showed that the maximum instantaneous intensity and duration of ·OH were low, the bacteria destruction was low and TPH oxidation was high after pre-oxidation with 900 mmol/L H2O2 (4.635 mL) by three batches dosing. The NH+4-N consumption (170.45 mg/kg) was high and the quantity of hydrocarbon-degrading microorganisms increased rapidly, then long-chain alkanes C21 to C30 (22%) and DOC (69%) degradation were high at the first 20 days in bio-remediation. Therefore, hydrocarbon degraders were induced to degrade long-alkane (42%) in 0 to 50 days by sufficient NH+4-N concentration consumption in the early bio-remediation stage. The activities of dehydrogenase and polyphenol oxidase reached a peak on the 20th day, indicating that the metabolic activity of microorganisms increased, and petroleum hydrocarbon degradation mainly occurred in this period.
To obtain a remediation method of Fenton pre-oxidation combined with bioremediation of oil-contaminated soil for efficient degradation of petroleum hydrocarbons (TPH), the characteristics of hydroxyl radical (·OH), NH+4-N concentration, DOC concentration, dehydrogenase and polyphenol oxidase activities and TPH removal with dosing different concentration of H2O2 by three batches were investigated in this study. The results showed that the maximum instantaneous intensity and duration of ·OH were low, the bacteria destruction was low and TPH oxidation was high after pre-oxidation with 900 mmol/L H2O2 (4.635 mL) by three batches dosing. The NH+4-N consumption (170.45 mg/kg) was high and the quantity of hydrocarbon-degrading microorganisms increased rapidly, then long-chain alkanes C21 to C30 (22%) and DOC (69%) degradation were high at the first 20 days in bio-remediation. Therefore, hydrocarbon degraders were induced to degrade long-alkane (42%) in 0 to 50 days by sufficient NH+4-N concentration consumption in the early bio-remediation stage. The activities of dehydrogenase and polyphenol oxidase reached a peak on the 20th day, indicating that the metabolic activity of microorganisms increased, and petroleum hydrocarbon degradation mainly occurred in this period.
2023, 41(2): 131-139.
doi: 10.13205/j.hjgc.202302018
Abstract:
Aiming at selective biodegradation of various alkanes in the petroleum contaminated soil, microbial communities in the soil were screened by regulating multiple soil solid phase Fe Fenton pre-oxidation. Then, the influence of soil microbial quantity, activity and community changes on the degradation of petroleum hydrocarbons was explored, and the microbial community characteristics for the balanced degradation of various alkanes were determined. The results showed that:after Fenton pre-oxidation of solid phase Fe with A45 (45 mmol/L citric acid) and F8.7 (8.7 mmol/L Fe2+), the metabolic activity of soil microorganisms was as high as 0.59 mol/kg (A45) and 0.60 mol/kg (F8.7), respectively. The petroleum hydrocarbon residual rate in the soil was reduced to 30% (A45) and 29% (F8.7), respectively. At the same time, there were soil microbial communities containing Acinetobacter, and Pseudomonas as dominant bacterial strains in the soil. The diversity of soil microorganisms was high, the community composition was rich, and the abundance of functional genes in alkane metabolism was high. Based on this situation, the balanced degradation of various alkanes was realized and promoted, and the biodegradation of various alkanes in the soil all reached 60%.
Aiming at selective biodegradation of various alkanes in the petroleum contaminated soil, microbial communities in the soil were screened by regulating multiple soil solid phase Fe Fenton pre-oxidation. Then, the influence of soil microbial quantity, activity and community changes on the degradation of petroleum hydrocarbons was explored, and the microbial community characteristics for the balanced degradation of various alkanes were determined. The results showed that:after Fenton pre-oxidation of solid phase Fe with A45 (45 mmol/L citric acid) and F8.7 (8.7 mmol/L Fe2+), the metabolic activity of soil microorganisms was as high as 0.59 mol/kg (A45) and 0.60 mol/kg (F8.7), respectively. The petroleum hydrocarbon residual rate in the soil was reduced to 30% (A45) and 29% (F8.7), respectively. At the same time, there were soil microbial communities containing Acinetobacter, and Pseudomonas as dominant bacterial strains in the soil. The diversity of soil microorganisms was high, the community composition was rich, and the abundance of functional genes in alkane metabolism was high. Based on this situation, the balanced degradation of various alkanes was realized and promoted, and the biodegradation of various alkanes in the soil all reached 60%.
2023, 41(2): 140-145,172.
doi: 10.13205/j.hjgc.202302019
Abstract:
Photocatalysis is a green and efficient pollutant treatment technology. The lack of utilization of the mid-infrared light region by traditional photocatalytic materials causes a waste of resources and limits the upper limit of pollutants' degradation efficiency. This study used photocatalytic degradation of TMP based on WO3-x to explore the degradation performance under different spectra and the degradation mechanism under the optimal degradation condition. The results showed that TMP was hardly degraded under dark and infrared light conditions. Compared with UV-visible light, the degradation of TMP under full spectrum conditions was increased by 44.8%. The mechanism of TMP degradation by WO3-x photocatalytic reaction in the two systems was similar, and O-2· and H2O2 were the active species that played the main role. During the degradation process, a large number of active radicals were generated on the catalyst surface and then entered the homogeneous system to promote the degradation of TMP. At the same time, temperature was not the dominant factor in improving the degradation rate in the reaction system, because WO3-x exhibited excellent degradation ability due to the effective absorption of the mid-infrared light region of the full spectrum.
Photocatalysis is a green and efficient pollutant treatment technology. The lack of utilization of the mid-infrared light region by traditional photocatalytic materials causes a waste of resources and limits the upper limit of pollutants' degradation efficiency. This study used photocatalytic degradation of TMP based on WO3-x to explore the degradation performance under different spectra and the degradation mechanism under the optimal degradation condition. The results showed that TMP was hardly degraded under dark and infrared light conditions. Compared with UV-visible light, the degradation of TMP under full spectrum conditions was increased by 44.8%. The mechanism of TMP degradation by WO3-x photocatalytic reaction in the two systems was similar, and O-2· and H2O2 were the active species that played the main role. During the degradation process, a large number of active radicals were generated on the catalyst surface and then entered the homogeneous system to promote the degradation of TMP. At the same time, temperature was not the dominant factor in improving the degradation rate in the reaction system, because WO3-x exhibited excellent degradation ability due to the effective absorption of the mid-infrared light region of the full spectrum.
2023, 41(2): 146-155.
doi: 10.13205/j.hjgc.202302020
Abstract:
The prevention and control of indoor low-concentration gaseous formaldehyde are still one of the great challenges faced by indoor environmental pollution. It is of great practical significance to design and synthesize catalysts with strong adsorption capacity, high catalytic oxidation performance and good stability. In this study, a series of Ag-Bi co-doped and nano-structured Ag/Bi-TiO2 photocatalysts were synthesized by the hydrothermal method and sol-gel method, which were applied for catalytic degradation of formaldehyde under visible light and non-dynamic conditions. The catalysts were characterized by XRD, SEM, BET, H2-TPR, UV-vis and XPS, and the effects of the preparation method, Ag-Bi incorporation amount and calcination temperatures on catalytic oxidation were investigated. The results showed that the Ag/Bi-TiO2-H catalyst prepared by the hydrothermal method exhibited the best degradation effect of formaldehyde, which degradation rate reached 94.1% in 48 hours, and formaldehyde concentration reduced from 1.076 mg/m3 to 0.093 mg/m3, significantly improving the catalytic performance of TiO2. The Ag2O/Ag, Bi3+ and TiO2 catalyst could be improved by coupling action between the microstructure, enhancing the absorption of visible light, to promote the formation of photoproduction electronics and their transferring. The surface hydroxyl and the adsorbed oxygen formed by coupling enhanced the adsorption and catalytic oxidation degradation of HCHO with low concentration. The possible principles of the catalysts were described, and the catalyst also showed excellent stability.
The prevention and control of indoor low-concentration gaseous formaldehyde are still one of the great challenges faced by indoor environmental pollution. It is of great practical significance to design and synthesize catalysts with strong adsorption capacity, high catalytic oxidation performance and good stability. In this study, a series of Ag-Bi co-doped and nano-structured Ag/Bi-TiO2 photocatalysts were synthesized by the hydrothermal method and sol-gel method, which were applied for catalytic degradation of formaldehyde under visible light and non-dynamic conditions. The catalysts were characterized by XRD, SEM, BET, H2-TPR, UV-vis and XPS, and the effects of the preparation method, Ag-Bi incorporation amount and calcination temperatures on catalytic oxidation were investigated. The results showed that the Ag/Bi-TiO2-H catalyst prepared by the hydrothermal method exhibited the best degradation effect of formaldehyde, which degradation rate reached 94.1% in 48 hours, and formaldehyde concentration reduced from 1.076 mg/m3 to 0.093 mg/m3, significantly improving the catalytic performance of TiO2. The Ag2O/Ag, Bi3+ and TiO2 catalyst could be improved by coupling action between the microstructure, enhancing the absorption of visible light, to promote the formation of photoproduction electronics and their transferring. The surface hydroxyl and the adsorbed oxygen formed by coupling enhanced the adsorption and catalytic oxidation degradation of HCHO with low concentration. The possible principles of the catalysts were described, and the catalyst also showed excellent stability.
2023, 41(2): 156-165.
doi: 10.13205/j.hjgc.202302021
Abstract:
Taking the disposal of huge-scale tailing slag generated in the construction of a fluorite lead-zinc mine in Chenzhou, Hunan province and greening of the dump as the research object, the physical and chemical defects of tailing slag were clarified by soil obstacle factor identification firstly. Then, biochemical fulvic acid (BFA), ammonium dihydrogen phosphate, zeolite and organic fertilizer were used to modify the corresponding properties. After that, a modified tailing matrix was used as the planting soil. Furthermore, a pot experiment in an artificial climate incubator combined with a pilot test in mine was used to evaluate the remediation effect of modifier and plant on tailing slag, and an ecological restoration method based on in-situ matrix improvement and direct vegetation of tailing was proposed eventually. The results showed that when the addition amount of BFA, ammonium dihydragen phosphace, zeolite and organic fertilizer was 0.5%, 0.4%, 2% and 15% respectively, the pH value and dry density of tailings decreased by 25.8% and 77.6% respectively, and non-capillary porosity, organic matter content, hydrolytic nitrogen content and available phosphorus content of tailings improved by 1.49 times, 26.7 times, 9.3 times and 20.9 times, respectively. The results of pot experiment and field pilot test showed that the comprehensive enrichment and transport ability of Eleusine indica to fluoride, lead and zinc, was the highest; Cosmos bipinnata had the best comprehensive accumulation capacity, and the enrichment amounts of lead, zinc and fluorine were 267.2 mg/kg, 432.8 mg/kg and 513.2 mg/kg, respectively; Amaranthus hybridus was the selected plant with the transport coefficients of lead, zinc and fluorine of 0.485, 1.208 and 1.810, respectively. In order to achieve the reclamation effect of fluorite lead-zinc mine, it is necessary to plant Eleusine indica, Cosmos bipinnata and Amaranthus hybridus simultaneously.
Taking the disposal of huge-scale tailing slag generated in the construction of a fluorite lead-zinc mine in Chenzhou, Hunan province and greening of the dump as the research object, the physical and chemical defects of tailing slag were clarified by soil obstacle factor identification firstly. Then, biochemical fulvic acid (BFA), ammonium dihydrogen phosphate, zeolite and organic fertilizer were used to modify the corresponding properties. After that, a modified tailing matrix was used as the planting soil. Furthermore, a pot experiment in an artificial climate incubator combined with a pilot test in mine was used to evaluate the remediation effect of modifier and plant on tailing slag, and an ecological restoration method based on in-situ matrix improvement and direct vegetation of tailing was proposed eventually. The results showed that when the addition amount of BFA, ammonium dihydragen phosphace, zeolite and organic fertilizer was 0.5%, 0.4%, 2% and 15% respectively, the pH value and dry density of tailings decreased by 25.8% and 77.6% respectively, and non-capillary porosity, organic matter content, hydrolytic nitrogen content and available phosphorus content of tailings improved by 1.49 times, 26.7 times, 9.3 times and 20.9 times, respectively. The results of pot experiment and field pilot test showed that the comprehensive enrichment and transport ability of Eleusine indica to fluoride, lead and zinc, was the highest; Cosmos bipinnata had the best comprehensive accumulation capacity, and the enrichment amounts of lead, zinc and fluorine were 267.2 mg/kg, 432.8 mg/kg and 513.2 mg/kg, respectively; Amaranthus hybridus was the selected plant with the transport coefficients of lead, zinc and fluorine of 0.485, 1.208 and 1.810, respectively. In order to achieve the reclamation effect of fluorite lead-zinc mine, it is necessary to plant Eleusine indica, Cosmos bipinnata and Amaranthus hybridus simultaneously.
2023, 41(2): 166-172.
doi: 10.13205/j.hjgc.202302022
Abstract:
Thermal desorption-stabilization was the main process for repairing heavy metal-organic co-contaminated soil. Thermal desorption had the dual effect of "activation" and "solidification" on heavy metals in the soil, so the thermal desorption-stabilization sequences will affect the stabilization efficiency of heavy metals. In this study, the co-contaminated soil containing cadmium (Cd) was used as the research object to analyze the effect of thermal desorption-stabilization (T-S) and stabilization-thermal desorption (S-T) processes on Cd stabilization efficiency, from the three levels of leaching rate, morphological distribution, and micromorphology. The results showed that the leaching rate of S-T process (42.26%) was lower than that of T-S process (52.11%). Due to the activation, solidification and stabilization effect of Cd, the ratio of weak acid extraction and residue of soil Cd treated by S-T process was 0.75 and 1.4 times that of T-S process, and the morphological distribution of Cd in the soil tended to be more stable. Scanning electron microscope (SEM) showed that S-T process had more significant soil particle crystallization than T-S process, which characterizes that Cd stabilization was better.
Thermal desorption-stabilization was the main process for repairing heavy metal-organic co-contaminated soil. Thermal desorption had the dual effect of "activation" and "solidification" on heavy metals in the soil, so the thermal desorption-stabilization sequences will affect the stabilization efficiency of heavy metals. In this study, the co-contaminated soil containing cadmium (Cd) was used as the research object to analyze the effect of thermal desorption-stabilization (T-S) and stabilization-thermal desorption (S-T) processes on Cd stabilization efficiency, from the three levels of leaching rate, morphological distribution, and micromorphology. The results showed that the leaching rate of S-T process (42.26%) was lower than that of T-S process (52.11%). Due to the activation, solidification and stabilization effect of Cd, the ratio of weak acid extraction and residue of soil Cd treated by S-T process was 0.75 and 1.4 times that of T-S process, and the morphological distribution of Cd in the soil tended to be more stable. Scanning electron microscope (SEM) showed that S-T process had more significant soil particle crystallization than T-S process, which characterizes that Cd stabilization was better.
2023, 41(2): 173-180.
doi: 10.13205/j.hjgc.202302023
Abstract:
Garbage classification is an important way to build a green city. The traditional garbage classification is commonly carried out manually, the classification is not thorough, and the labor intensity classification is high, which is not conducive to environmental protection and resource reuse. In order to improve the accuracy of garbage classification, this paper proposed a lightweight network model LW-GCNet (light weight garbage classify network) based on VGG16. The network model performed feature extraction by introducing depthwise separable convolution and SE (squeeze-and-excitation) modules, and organically fused the shallow and deep features of junk images. These modules enhanced the dependencies between channels of garbage images to be classified while reducing the computational complexity of the model and providing multi-level semantic information for accurate classification. In addition, the LW-GCNet model adopted adaptive max pooling and global average pooling to replace the fully connected layer in the VGG16 network, which effectively reduced the number of parameters. The performance of LW-GCNet was validated using the dataset GRAB125 consisting of four types of garbage images. The experimental results showed that, on the premise of ensuring the recognition speed, the average recognition accuracy rate of this method reached 77.17%, and the parameter quantity was 3.15 M, making it easy to be deployed in outdoor embedded systems.
Garbage classification is an important way to build a green city. The traditional garbage classification is commonly carried out manually, the classification is not thorough, and the labor intensity classification is high, which is not conducive to environmental protection and resource reuse. In order to improve the accuracy of garbage classification, this paper proposed a lightweight network model LW-GCNet (light weight garbage classify network) based on VGG16. The network model performed feature extraction by introducing depthwise separable convolution and SE (squeeze-and-excitation) modules, and organically fused the shallow and deep features of junk images. These modules enhanced the dependencies between channels of garbage images to be classified while reducing the computational complexity of the model and providing multi-level semantic information for accurate classification. In addition, the LW-GCNet model adopted adaptive max pooling and global average pooling to replace the fully connected layer in the VGG16 network, which effectively reduced the number of parameters. The performance of LW-GCNet was validated using the dataset GRAB125 consisting of four types of garbage images. The experimental results showed that, on the premise of ensuring the recognition speed, the average recognition accuracy rate of this method reached 77.17%, and the parameter quantity was 3.15 M, making it easy to be deployed in outdoor embedded systems.
2023, 41(2): 181-187.
doi: 10.13205/j.hjgc.202302024
Abstract:
Decoration waste has the characteristics of multiple and complex components and large fluctuation of waste properties. The treatment process should be determined by on-site diligence in the waste source area. Taking a typical decoration waste project in Shanghai as an example, its process route is "two-stage crushing+multi-stage sorting", and there is a significant difference between the actual and the designed material balance after the primary screening unit. The utilization rate of the back-end sorting equipment was at a low level. The practical process improvement measures included material diversion or adjusting the upper sieve plate specification. After the improvement, the proportion of the actual receiving and processing load of the three box-type air separators with the same specification was close, and the material distribution uniformity tended to be reasonable. In terms of economic benefits, the operation cost of the treatment line was converted to about 114.49 yuan/t, of which the labour cost, residue incineration disposal cost and residue landfill disposal cost accounted for 20.69%, 19.22% and 14.11% respectively; the operating income was about 26.45 yuan/t, mainly from the sale of recycled brick products and recycled aggregates. The operation cost and product quality of brick making line were significantly affected by the cement mixing ratio. When the cement mixing ratio increased from 10% to 20%, the average compressive strength of recycled standard bricks increased from 13.9 MPa to 18.1 MPa; when the optimum cement mixing ratio was 15%, it was difficult for the brick making line to maintain the balance of revenue and expenditure. The decoration waste project had low investment income and economic benefit without government support, which is the main bottleneck of the industry development in this field.
Decoration waste has the characteristics of multiple and complex components and large fluctuation of waste properties. The treatment process should be determined by on-site diligence in the waste source area. Taking a typical decoration waste project in Shanghai as an example, its process route is "two-stage crushing+multi-stage sorting", and there is a significant difference between the actual and the designed material balance after the primary screening unit. The utilization rate of the back-end sorting equipment was at a low level. The practical process improvement measures included material diversion or adjusting the upper sieve plate specification. After the improvement, the proportion of the actual receiving and processing load of the three box-type air separators with the same specification was close, and the material distribution uniformity tended to be reasonable. In terms of economic benefits, the operation cost of the treatment line was converted to about 114.49 yuan/t, of which the labour cost, residue incineration disposal cost and residue landfill disposal cost accounted for 20.69%, 19.22% and 14.11% respectively; the operating income was about 26.45 yuan/t, mainly from the sale of recycled brick products and recycled aggregates. The operation cost and product quality of brick making line were significantly affected by the cement mixing ratio. When the cement mixing ratio increased from 10% to 20%, the average compressive strength of recycled standard bricks increased from 13.9 MPa to 18.1 MPa; when the optimum cement mixing ratio was 15%, it was difficult for the brick making line to maintain the balance of revenue and expenditure. The decoration waste project had low investment income and economic benefit without government support, which is the main bottleneck of the industry development in this field.
2023, 41(2): 188-196,218.
doi: 10.13205/j.hjgc.202302025
Abstract:
Based on the phenomenon of substandard dioxin emission from waste pyrolysis flue gas, this paper proposed a method of quantitative oxygen supply and stratified dioxin control based on the analysis of the waste pyrolysis and dioxin generation mechanism, used a combination of numerical analysis and experimental test to simulate the airflow organization inside the furnace and waste pyrolysis process, and discussed the effect of air supply on dioxin synthesis. The results showed that the overall distribution of airflow inside the pyrolysis furnace was relatively uniform, which ensured the stable pyrolysis of waste. The temperature stratification along the axial direction of the pyrolysis furnace was consistent with the theoretical analysis, but there was a dioxin synthesis atmosphere in the transition layer between the combustion layer and the pyrolysis layer; the measured results of the pyrolysis furnace temperature were in good agreement with the simulation results as a whole; a comprehensive comparison suggested that operation of the pyrolysis furnace with an air excess factor of 0.3 was more conducive to reducing dioxin generation, and the waste treatment capacity was 2.4 t/d. The field test result showed that, except for the particulate matter concentration exceeded the standard, the other conventional pollutants from pyrolysis furnace outlet flue gas and dioxin emission concentration met the Standard for Pollution Control of Domestic Waste Incineration (GB 18485-2014). The commercially available common furnace model dioxin outlet concentration was 0.44 ng-TEQ/m3, exceeding the national emission standard limit of 0.1 ng-TEQ/m3. The experimental results of the two furnace types proved that dioxin generation in the flue gas could be effectively suppressed by quantitative oxygen supply and stratified control on the basis of uniform gas distribution in the pyrolysis furnace. The study could provide a theoretical basis for the control of dioxins in low-temperature pyrolysis of domestic waste.
Based on the phenomenon of substandard dioxin emission from waste pyrolysis flue gas, this paper proposed a method of quantitative oxygen supply and stratified dioxin control based on the analysis of the waste pyrolysis and dioxin generation mechanism, used a combination of numerical analysis and experimental test to simulate the airflow organization inside the furnace and waste pyrolysis process, and discussed the effect of air supply on dioxin synthesis. The results showed that the overall distribution of airflow inside the pyrolysis furnace was relatively uniform, which ensured the stable pyrolysis of waste. The temperature stratification along the axial direction of the pyrolysis furnace was consistent with the theoretical analysis, but there was a dioxin synthesis atmosphere in the transition layer between the combustion layer and the pyrolysis layer; the measured results of the pyrolysis furnace temperature were in good agreement with the simulation results as a whole; a comprehensive comparison suggested that operation of the pyrolysis furnace with an air excess factor of 0.3 was more conducive to reducing dioxin generation, and the waste treatment capacity was 2.4 t/d. The field test result showed that, except for the particulate matter concentration exceeded the standard, the other conventional pollutants from pyrolysis furnace outlet flue gas and dioxin emission concentration met the Standard for Pollution Control of Domestic Waste Incineration (GB 18485-2014). The commercially available common furnace model dioxin outlet concentration was 0.44 ng-TEQ/m3, exceeding the national emission standard limit of 0.1 ng-TEQ/m3. The experimental results of the two furnace types proved that dioxin generation in the flue gas could be effectively suppressed by quantitative oxygen supply and stratified control on the basis of uniform gas distribution in the pyrolysis furnace. The study could provide a theoretical basis for the control of dioxins in low-temperature pyrolysis of domestic waste.
2023, 41(2): 197-204.
doi: 10.13205/j.hjgc.202302026
Abstract:
The prediction of air quality is of great significance for formulating environmental governance policies. Aiming at the problems of instability and weak generalization ability of the single model method, a multi-model fusion prediction method of air quality index (AQI) based on the inverse variance weight distribution method and fusion of three single model methods was proposed. Firstly, taking Beijing as an example, the air quality index prediction dataset was constructed. Secondly, five models, LSTM, GRU, Bi-LSTM, ARIMA and MLR, were constructed to predict the dataset, and the prediction results of these models were compared. Finally, in the multi-model fusion method, the inverse variance method was used to calculate the weight of three monomer models with high prediction accuracy, and the inverse variance fusion prediction model was constructed according to the calculated weight. Compared with the three monomer models with higher prediction accuracy and the weighted average fusion prediction model, the prediction accuracy, R2 of the inverse variance fusion prediction model for air quality index was improved by 3.9%, 3.4%, 1.6% and 0.5% respectively, reaching 0.933. The results showed that the proposed inverse variance fusion prediction model integrated the advantages of each monomer prediction model, which could improve the prediction accuracy of air quality index.
The prediction of air quality is of great significance for formulating environmental governance policies. Aiming at the problems of instability and weak generalization ability of the single model method, a multi-model fusion prediction method of air quality index (AQI) based on the inverse variance weight distribution method and fusion of three single model methods was proposed. Firstly, taking Beijing as an example, the air quality index prediction dataset was constructed. Secondly, five models, LSTM, GRU, Bi-LSTM, ARIMA and MLR, were constructed to predict the dataset, and the prediction results of these models were compared. Finally, in the multi-model fusion method, the inverse variance method was used to calculate the weight of three monomer models with high prediction accuracy, and the inverse variance fusion prediction model was constructed according to the calculated weight. Compared with the three monomer models with higher prediction accuracy and the weighted average fusion prediction model, the prediction accuracy, R2 of the inverse variance fusion prediction model for air quality index was improved by 3.9%, 3.4%, 1.6% and 0.5% respectively, reaching 0.933. The results showed that the proposed inverse variance fusion prediction model integrated the advantages of each monomer prediction model, which could improve the prediction accuracy of air quality index.
2023, 41(2): 205-212.
doi: 10.13205/j.hjgc.202302027
Abstract:
Accurate, timely and environmentally friendly detection of water Chemical oxygen demand has become an important research topic in the field of environmental monitoring. A visible-light-responsive BiVO4/rGO film electrode was prepared by solution combustion method and rotating coating method for the determination of COD. The structure of the composite electrode was investigated by X-ray diffraction (XRD), surface area analysis(BET) and scanning electron microscope analysis(SEM). The results showed that the substrate was completely covered by BiVO4/rGO. The photoelectric properties were tested by cyclic voltammetry(CV), photocurrent-time (I-t) method, and the best performance was obtained when the calcination temperature was 500℃, the doped rGO was 5 mL, and the coating thickness was 4 layers. The results showed that stable and reliable test results could be obtained in the condition of a working voltage of 1.0 V, supporting electrolyte of 0.1 mol/L Na2SO4, illumination intensity of 400 μW/cm2 and pH of 6~8. The determination range of COD by BiVO4/rGO film electrode was 12.18~719.8 mg/L, and there was a good linear relationship between the transfer net charge (Qnet) and the theoretical COD value. When it was applied to the determination of COD in real water samples, the steady photocurrent could be reached within 60 seconds. The results were in good agreement with the national standard method, and the relative deviation was less than 5%. Therefore, BiVO4/rGO coated electrode has the advantages of fast response, wide linear range and convenient operation, which can replace the traditional COD determination instrument.
Accurate, timely and environmentally friendly detection of water Chemical oxygen demand has become an important research topic in the field of environmental monitoring. A visible-light-responsive BiVO4/rGO film electrode was prepared by solution combustion method and rotating coating method for the determination of COD. The structure of the composite electrode was investigated by X-ray diffraction (XRD), surface area analysis(BET) and scanning electron microscope analysis(SEM). The results showed that the substrate was completely covered by BiVO4/rGO. The photoelectric properties were tested by cyclic voltammetry(CV), photocurrent-time (I-t) method, and the best performance was obtained when the calcination temperature was 500℃, the doped rGO was 5 mL, and the coating thickness was 4 layers. The results showed that stable and reliable test results could be obtained in the condition of a working voltage of 1.0 V, supporting electrolyte of 0.1 mol/L Na2SO4, illumination intensity of 400 μW/cm2 and pH of 6~8. The determination range of COD by BiVO4/rGO film electrode was 12.18~719.8 mg/L, and there was a good linear relationship between the transfer net charge (Qnet) and the theoretical COD value. When it was applied to the determination of COD in real water samples, the steady photocurrent could be reached within 60 seconds. The results were in good agreement with the national standard method, and the relative deviation was less than 5%. Therefore, BiVO4/rGO coated electrode has the advantages of fast response, wide linear range and convenient operation, which can replace the traditional COD determination instrument.
2023, 41(2): 213-218.
doi: 10.13205/j.hjgc.202302028
Abstract:
Facing the source reduction requirements of the construction of Zero-Waste Cities in China, scientific prediction of the spatio-temporal characteristics of domestic waste is an essential fundamental work for the overall planning of domestic waste management. The annual output of domestic waste in the study area reaches 126,000 tons in 2020, and the increase is becoming significant in recent years. It is urgent to conduct a detailed analysis of domestic waste's temporal and spatial characteristics to serve the construction of local Zero-Waste Cities' construction. Based on the comprehensive analysis of the historical domestic waste data of the study area, a linear relationship between the night light in the study area and the annual output of domestic waste was established to form a high-fit regression model with an R2 of 0.92; based on the Kriging algorithm of ArcGIS, using 2.25 hectares as the spatial unit, a domestic waste spatial distribution grid model based on night lights was established; the Thiessen polygon algorithm was used to interpolate each domestic waste collection point to obtain the annual domestic waste load status of each collection point, revealed the spatial imbalance of urban and rural waste production.
Facing the source reduction requirements of the construction of Zero-Waste Cities in China, scientific prediction of the spatio-temporal characteristics of domestic waste is an essential fundamental work for the overall planning of domestic waste management. The annual output of domestic waste in the study area reaches 126,000 tons in 2020, and the increase is becoming significant in recent years. It is urgent to conduct a detailed analysis of domestic waste's temporal and spatial characteristics to serve the construction of local Zero-Waste Cities' construction. Based on the comprehensive analysis of the historical domestic waste data of the study area, a linear relationship between the night light in the study area and the annual output of domestic waste was established to form a high-fit regression model with an R2 of 0.92; based on the Kriging algorithm of ArcGIS, using 2.25 hectares as the spatial unit, a domestic waste spatial distribution grid model based on night lights was established; the Thiessen polygon algorithm was used to interpolate each domestic waste collection point to obtain the annual domestic waste load status of each collection point, revealed the spatial imbalance of urban and rural waste production.
2023, 41(2): 219-226.
doi: 10.13205/j.hjgc.202302029
Abstract:
Occurrence of antibiotics in groundwater environment of major cities in China was explored based on the integration of the research results in recent 10 years, and the ecological risks and health risks of typical antibiotics were evaluated based on risk quotient method. The results showed that:1)in groundwater of major cities in China, a total of 57 types of antibiotics belonging to 7 categories were detected. Sulfa and quinolones were the main pollutants, with the most types in high cumulative concentration, followed by macrolides and tetracycline; 2) sulfamethoxazole, sulfathiazole and clindamycin had high ecological risk in groundwater environment. The combined ecological risk of groundwater antibiotics in northern cities was higher than that in southern cities, in which quinolone, sulfa and tetracycline were the three categories of antibiotics with high ecological risk rates and in the largest proportion contributing to the urban groundwater ecological risk;3) in the present, the investigated antibiotics did not appear to pose direct human health risk through drinking water based on health risk quotient method.
Occurrence of antibiotics in groundwater environment of major cities in China was explored based on the integration of the research results in recent 10 years, and the ecological risks and health risks of typical antibiotics were evaluated based on risk quotient method. The results showed that:1)in groundwater of major cities in China, a total of 57 types of antibiotics belonging to 7 categories were detected. Sulfa and quinolones were the main pollutants, with the most types in high cumulative concentration, followed by macrolides and tetracycline; 2) sulfamethoxazole, sulfathiazole and clindamycin had high ecological risk in groundwater environment. The combined ecological risk of groundwater antibiotics in northern cities was higher than that in southern cities, in which quinolone, sulfa and tetracycline were the three categories of antibiotics with high ecological risk rates and in the largest proportion contributing to the urban groundwater ecological risk;3) in the present, the investigated antibiotics did not appear to pose direct human health risk through drinking water based on health risk quotient method.
2023, 41(2): 227-233,246.
doi: 10.13205/j.hjgc.202302030
Abstract:
Three lines and one list is an important means for ecological and environmental protection to participate in the fine management of land and space, and the bottom line of water environment quality is an important grasp for improving the ability of regional water environment management of China. Aiming at the technical problem of defining the bottom line of water environment quality, the technical method of defining the bottom line was refined on the basis of relevant guidelines. Taking Jiangmen City in the Pearl River Delta as the research object, the city was divided into 94 water environment control units. Agricultural sources and domestic sources were the main sources of water pollutants in Jiangmen City. The total amount of water pollutants entering the river in Xinhui District, Kaiping City and Taishan City exceeded 60% of that in Jiangmen City. In order to meet the water quality improvement requirements, the current pollution load of COD, ammonia nitrogen and TP should be reduced by least 14%, 15% and 29% by 2025. A water environment zoning management and control system was established with priority protection areas, key management and control areas and general management and control areas as the main body. The proportion of the three types of zoning areas was 9.4%, 31.9% and 58.7% respectively. This paper discussed the key points of the implementation, renewal and adjustment of the bottom line of water environment quality. The research results can provide theoretical and practical reference for other cities in the Pearl River Delta.
Three lines and one list is an important means for ecological and environmental protection to participate in the fine management of land and space, and the bottom line of water environment quality is an important grasp for improving the ability of regional water environment management of China. Aiming at the technical problem of defining the bottom line of water environment quality, the technical method of defining the bottom line was refined on the basis of relevant guidelines. Taking Jiangmen City in the Pearl River Delta as the research object, the city was divided into 94 water environment control units. Agricultural sources and domestic sources were the main sources of water pollutants in Jiangmen City. The total amount of water pollutants entering the river in Xinhui District, Kaiping City and Taishan City exceeded 60% of that in Jiangmen City. In order to meet the water quality improvement requirements, the current pollution load of COD, ammonia nitrogen and TP should be reduced by least 14%, 15% and 29% by 2025. A water environment zoning management and control system was established with priority protection areas, key management and control areas and general management and control areas as the main body. The proportion of the three types of zoning areas was 9.4%, 31.9% and 58.7% respectively. This paper discussed the key points of the implementation, renewal and adjustment of the bottom line of water environment quality. The research results can provide theoretical and practical reference for other cities in the Pearl River Delta.
2023, 41(2): 234-246.
doi: 10.13205/j.hjgc.202302031
Abstract:
Petroleum hydrocarbon contaminants are complex organic compounds, and it would cause great risk to the ecological environment and public health. Currently, microbial technology becomes a popular remediation technology for petroleum hydrocarbon contaminations. Microorganisms use the pollutants as a carbon source and metabolize and degrade it through a series of enzymatic catalysis. For increasing the application of microbial remediation of petroleum hydrocarbon pollution, the method of rational design of enzymes at key steps can be used to increase the microbial degradation rates of petroleum hydrocarbons. This review summarizes the main components and structures of petroleum hydrocarbons, metabolic pathways, functional genes and key enzyme types, as well as the application status of omics and synthetic biology technologies in the research of petroleum hydrocarbon degradation and metabolism mechanism, providing a reference for further improving the application prospects of microbial remediation technology in the field of petroleum hydrocarbon pollution.
Petroleum hydrocarbon contaminants are complex organic compounds, and it would cause great risk to the ecological environment and public health. Currently, microbial technology becomes a popular remediation technology for petroleum hydrocarbon contaminations. Microorganisms use the pollutants as a carbon source and metabolize and degrade it through a series of enzymatic catalysis. For increasing the application of microbial remediation of petroleum hydrocarbon pollution, the method of rational design of enzymes at key steps can be used to increase the microbial degradation rates of petroleum hydrocarbons. This review summarizes the main components and structures of petroleum hydrocarbons, metabolic pathways, functional genes and key enzyme types, as well as the application status of omics and synthetic biology technologies in the research of petroleum hydrocarbon degradation and metabolism mechanism, providing a reference for further improving the application prospects of microbial remediation technology in the field of petroleum hydrocarbon pollution.
