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2020 Vol. 38, No. 8
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2020, 38(8): 1-7.
doi: 10.13205/j.hjgc.202008001
Abstract:
To establish a sustainable society, the Japanese government vigorously promoted the methane fermentation for the treatment of the municipal organic solid waste (MOSW) to achieve waste reduction and resource recovery. This paper introduced two full-scale plants in Japan, Nagaoka Food Waste Biogas Generation Center and Toyohashi Biomass Resource Utilization Center, for the anaerobic treatment of MOSW. The stable performance and the power generation indicated the feasibility of waste reduction and resource recovery from the MOSW by methane fermentation. Besides, some recent comprehensive investigations on the performance of the mono digestion and co-digestion in the treatment of the three most critical fractions of MOSW: food waste, sewage sludge and paper waste, were summarized. The recent researches on the application of anaerobic membrane bioreactor (AnMBR) for the MOSW treatment was also introduced. In addition, an analysis of the energy production potential was conducted for a city with a population of 1 million, based on the social investigation and experimental results.
To establish a sustainable society, the Japanese government vigorously promoted the methane fermentation for the treatment of the municipal organic solid waste (MOSW) to achieve waste reduction and resource recovery. This paper introduced two full-scale plants in Japan, Nagaoka Food Waste Biogas Generation Center and Toyohashi Biomass Resource Utilization Center, for the anaerobic treatment of MOSW. The stable performance and the power generation indicated the feasibility of waste reduction and resource recovery from the MOSW by methane fermentation. Besides, some recent comprehensive investigations on the performance of the mono digestion and co-digestion in the treatment of the three most critical fractions of MOSW: food waste, sewage sludge and paper waste, were summarized. The recent researches on the application of anaerobic membrane bioreactor (AnMBR) for the MOSW treatment was also introduced. In addition, an analysis of the energy production potential was conducted for a city with a population of 1 million, based on the social investigation and experimental results.
2020, 38(8): 8-12.
doi: 10.13205/j.hjgc.202008002
Abstract:
Gas-inducing agitator system and disk turbine agitator system were applied to autothermal thermophilic aerobic digestion system; this study compared the oxygen supply performance and economic feasibility of these two agitator systems. The research showed that the gas-inducing agitator system was suitable for a stirring rate of 500~1100 r/min, a lower or higher stirring rate would affect the oxygen supply performance; with a stirring rate of 900 r/min and air flowrate of 0.5 L/min (by volume), the KLα value of the disk turbine agitator system was 108.01 h-1, lower than that of gas-inducing agitator system of 124.52 h-1; disk turbine agitator system under the same stirring rate and air flowrate, KLα value at 50 ℃ was greater than that of 30 ℃. To achieve the same KLα value under 1000 r/min, the power consumption of the gas-inducing agitator system was about 1/3 of that of the disk turbine agitator system.
Gas-inducing agitator system and disk turbine agitator system were applied to autothermal thermophilic aerobic digestion system; this study compared the oxygen supply performance and economic feasibility of these two agitator systems. The research showed that the gas-inducing agitator system was suitable for a stirring rate of 500~1100 r/min, a lower or higher stirring rate would affect the oxygen supply performance; with a stirring rate of 900 r/min and air flowrate of 0.5 L/min (by volume), the KLα value of the disk turbine agitator system was 108.01 h-1, lower than that of gas-inducing agitator system of 124.52 h-1; disk turbine agitator system under the same stirring rate and air flowrate, KLα value at 50 ℃ was greater than that of 30 ℃. To achieve the same KLα value under 1000 r/min, the power consumption of the gas-inducing agitator system was about 1/3 of that of the disk turbine agitator system.
2020, 38(8): 13-20.
doi: 10.13205/j.hjgc.202008003
Abstract:
Hydrogen production from anaerobic fermentation is an important way for sludge resource utilization. However, the emerging contaminants will be transferred to sludge through various ways in the process of sewage treatment, which will affect the subsequent treatment of sludge. This paper summarized the pollution status of four emerging contaminants in sludge, including antibiotics, surfactants, industrial additives and brominated flame retardants (BFR), and expounded the impact of these emerging contaminants on the hydrogen production from sludge fermentation, and revealed the relevant mechanisms. Meanwhile, the degradation and transformation of the emerging contaminants in the sludge fermentation system were analyzed. Finally, the future research of the emerging contaminants in sludge was prospected, in order to facilitate the utilization of sludge resources.
Hydrogen production from anaerobic fermentation is an important way for sludge resource utilization. However, the emerging contaminants will be transferred to sludge through various ways in the process of sewage treatment, which will affect the subsequent treatment of sludge. This paper summarized the pollution status of four emerging contaminants in sludge, including antibiotics, surfactants, industrial additives and brominated flame retardants (BFR), and expounded the impact of these emerging contaminants on the hydrogen production from sludge fermentation, and revealed the relevant mechanisms. Meanwhile, the degradation and transformation of the emerging contaminants in the sludge fermentation system were analyzed. Finally, the future research of the emerging contaminants in sludge was prospected, in order to facilitate the utilization of sludge resources.
2020, 38(8): 21-26,12.
doi: 10.13205/j.hjgc.202008004
Abstract:
Anaerobic fermentation of different pretreated sludge for volatile fatty acids production can not only effectively treat sludge problems but also realize resource cycling. In this paper, batch tests were conducted to investigate the volatile fatty acids production efficiency from anaerobic fermentation by acid (pH=3 and pH=4), alkali (pH=10 and pH=11) and low temperature (70 ℃, 90 ℃) pretreatment. The results showed that the accumulation of volatile fatty acids mainly occurred in the first 24h during anaerobic fermentation process, and ranked as pH=11 > 90 ℃ > pH=10 > 70 ℃ > pH=3 > pH=4 > control group, and acid production by alkali treatment had the most obvious advantages, while the effect of acid treatment was the worst. Acetic acid was the main component of volatile fatty acids, and its highest concentration was 1232.31 mg/L (pH=11), which was 5.2 times higher than that of control group. Methane production rose slowly at the later stage of anaerobic fermentation, and volatile fatty acids was consumed in the methanogensis process. Therefore, considering the economy and consumption of volatile fatty acids by acidophilic methanogens, 24 hours was the best fermentation time.
Anaerobic fermentation of different pretreated sludge for volatile fatty acids production can not only effectively treat sludge problems but also realize resource cycling. In this paper, batch tests were conducted to investigate the volatile fatty acids production efficiency from anaerobic fermentation by acid (pH=3 and pH=4), alkali (pH=10 and pH=11) and low temperature (70 ℃, 90 ℃) pretreatment. The results showed that the accumulation of volatile fatty acids mainly occurred in the first 24h during anaerobic fermentation process, and ranked as pH=11 > 90 ℃ > pH=10 > 70 ℃ > pH=3 > pH=4 > control group, and acid production by alkali treatment had the most obvious advantages, while the effect of acid treatment was the worst. Acetic acid was the main component of volatile fatty acids, and its highest concentration was 1232.31 mg/L (pH=11), which was 5.2 times higher than that of control group. Methane production rose slowly at the later stage of anaerobic fermentation, and volatile fatty acids was consumed in the methanogensis process. Therefore, considering the economy and consumption of volatile fatty acids by acidophilic methanogens, 24 hours was the best fermentation time.
2020, 38(8): 27-33,95.
doi: 10.13205/j.hjgc.202008005
Abstract:
In this research, polyvinyl alcohol/cellulose composite porous materials with high content of fly ash were prepared. The preparation process of the composite was simple, without requirement of high-temperature or high-pressure conditions. The characterization of the fly ash composites was analyzed via XRF, XRD, FT-IR, SEM, and mercury porosimetry. The effects of the mixture ratio of raw materials and drying temperature on the properties of the samples were explored. It was found that PVA could effectively increase the unconfined compressive strength of the composites, and cellulose was useful to improve the porous structure of the composites. The pore structure of the composites mainly came from the bubble polymerization in the process of water evaporation. The drying temperature was an essential factor that had influence on the pore structure, when the samples were prepared under the condition without external pressure. When the content of fly ash was 80%, polyvinyl alcohol was 10 wt% and cellulose was 10 wt%, the composite had good properties in porosity, pore structure, compressive strength, water absorption and water retention capacity. The comprehensive performance of the fly ash-based materials could be further developed by improving the internal porous structure and activation of the chemical functional groups. Further research needs to be conducted, to make the hydrophilic fly ash composites with certain compressive strength and provide good alternative for the utilization of fly ash.
In this research, polyvinyl alcohol/cellulose composite porous materials with high content of fly ash were prepared. The preparation process of the composite was simple, without requirement of high-temperature or high-pressure conditions. The characterization of the fly ash composites was analyzed via XRF, XRD, FT-IR, SEM, and mercury porosimetry. The effects of the mixture ratio of raw materials and drying temperature on the properties of the samples were explored. It was found that PVA could effectively increase the unconfined compressive strength of the composites, and cellulose was useful to improve the porous structure of the composites. The pore structure of the composites mainly came from the bubble polymerization in the process of water evaporation. The drying temperature was an essential factor that had influence on the pore structure, when the samples were prepared under the condition without external pressure. When the content of fly ash was 80%, polyvinyl alcohol was 10 wt% and cellulose was 10 wt%, the composite had good properties in porosity, pore structure, compressive strength, water absorption and water retention capacity. The comprehensive performance of the fly ash-based materials could be further developed by improving the internal porous structure and activation of the chemical functional groups. Further research needs to be conducted, to make the hydrophilic fly ash composites with certain compressive strength and provide good alternative for the utilization of fly ash.
2020, 38(8): 34-40.
doi: 10.13205/j.hjgc.202008006
Abstract:
In this study, humic acid-modified biofuel ash was used as the carrier to immobilize the petroleum degrading bacteria for remediating the crude oil contaminated soil, and the best modification conditions of biofuel ash and the remediation effect of immobilized bacteria were investigated. The results showed that the optimum conditions of modified biofuel ash were: 10~40 mesh for the particle size, 1∶1 for the liquid ratio and 4 h for the modification time. After modification, the biofuel ash had rich pore-like structures and rough surface, which were favorable to the adsorption of bacteria and the immobilized number reached 1.5×109 CFU/g. After 60 days’ remediation, the removal efficiency of total petroleum hydrocarbon was 51.9%, which was higher than free bacteria by 25.0%, and the removal efficiency of long-chain n-alkanes, aromatic hydrocarbons and colloids was improved by 9.6%, 31.7% and 37.5%, respectively. The application of immobilized biofuel ash protected and supported the petroleum degrading bacteria, enhanced the basal respiration rate and the soil enzyme activity, thus achieved highly efficient degradation of petroleum hydrocarbon in soil. Therefore, humic acid-modified biofuel ash is a promising immobilization material in the field of petroleum contaminated soil remediation.
In this study, humic acid-modified biofuel ash was used as the carrier to immobilize the petroleum degrading bacteria for remediating the crude oil contaminated soil, and the best modification conditions of biofuel ash and the remediation effect of immobilized bacteria were investigated. The results showed that the optimum conditions of modified biofuel ash were: 10~40 mesh for the particle size, 1∶1 for the liquid ratio and 4 h for the modification time. After modification, the biofuel ash had rich pore-like structures and rough surface, which were favorable to the adsorption of bacteria and the immobilized number reached 1.5×109 CFU/g. After 60 days’ remediation, the removal efficiency of total petroleum hydrocarbon was 51.9%, which was higher than free bacteria by 25.0%, and the removal efficiency of long-chain n-alkanes, aromatic hydrocarbons and colloids was improved by 9.6%, 31.7% and 37.5%, respectively. The application of immobilized biofuel ash protected and supported the petroleum degrading bacteria, enhanced the basal respiration rate and the soil enzyme activity, thus achieved highly efficient degradation of petroleum hydrocarbon in soil. Therefore, humic acid-modified biofuel ash is a promising immobilization material in the field of petroleum contaminated soil remediation.
2020, 38(8): 41-46.
doi: 10.13205/j.hjgc.202008007
Abstract:
Food waste tends to rot and stink for high levels of water and organic matter, thus affecting its resource utilization and urban environment seriously. In this paper, natural sealing and anaerobic preservation methods of food waste were used to investigate the effect of different preservation methods on bacteriostatic effect with the increase of fermentation duration. The results showed that the order of Escherichia coli quantity in samples under different preservation methods was the anaerobic preservation without adding lactobacillus＜the anaerobic preservation group after adding lactobacillus＜the natural preservation group, which was consistent with the concentration of hydrolytic acidification products (organic carboxylic acid and ethanol, etc.) and the percentage of lactic acid+acetic acid to the hydrolytic products, from high to low, during sample preservation. To explore bacteriostatic effect of organic acid in the process of anaerobic preservation, Escherichia coli was chosen as the spoilage organisms to carry out Oxford cup bacteriostatic experiment and 96 orifice synergy bacteriostatic experiment. The results showed that the main inhibitory action was acetic acid molecule and lactic acid molecule rather than H+. The minimum inhibitory concentrations of lactic acid, acetic acid and ethanol were 2.5, 1.25, 35 g/L, respectively, and the FIC indexes of lactic acid+acetic acid, lactic acid+ethanol and acetic acid+ethanol were 0.12, 0.03, 0.22, respectively, indicating that each pair of the three hydrolytic products had synergistic bacteriostatic effect.
Food waste tends to rot and stink for high levels of water and organic matter, thus affecting its resource utilization and urban environment seriously. In this paper, natural sealing and anaerobic preservation methods of food waste were used to investigate the effect of different preservation methods on bacteriostatic effect with the increase of fermentation duration. The results showed that the order of Escherichia coli quantity in samples under different preservation methods was the anaerobic preservation without adding lactobacillus＜the anaerobic preservation group after adding lactobacillus＜the natural preservation group, which was consistent with the concentration of hydrolytic acidification products (organic carboxylic acid and ethanol, etc.) and the percentage of lactic acid+acetic acid to the hydrolytic products, from high to low, during sample preservation. To explore bacteriostatic effect of organic acid in the process of anaerobic preservation, Escherichia coli was chosen as the spoilage organisms to carry out Oxford cup bacteriostatic experiment and 96 orifice synergy bacteriostatic experiment. The results showed that the main inhibitory action was acetic acid molecule and lactic acid molecule rather than H+. The minimum inhibitory concentrations of lactic acid, acetic acid and ethanol were 2.5, 1.25, 35 g/L, respectively, and the FIC indexes of lactic acid+acetic acid, lactic acid+ethanol and acetic acid+ethanol were 0.12, 0.03, 0.22, respectively, indicating that each pair of the three hydrolytic products had synergistic bacteriostatic effect.
2020, 38(8): 47-51.
doi: 10.13205/j.hjgc.202008008
Abstract:
The output of kitchen waste in China accounts for more than half of the total municipal solid waste. It is an urgent problem to promote the resource utilization and harmless treatment of kitchen waste. The typical comprehensive treatment project of kitchen waste introduced in this paper consists of five parts: pretreatment system, anaerobic fermentation system, biogas purification and storage system, biogas residue and biogas liquid treatment system and deodorization system, covering an area of 19000 m2, with a total investment of RMB 99.78 million and a kitchen waste treatment scale of 200 t/d. The average biogas output is 7740 m3/d, in which the methane content is more than 60%. The reduction and recycling of kitchen waste was realized well. It can be taken as a reference for the disposal of kitchen waste in other cities in China.
The output of kitchen waste in China accounts for more than half of the total municipal solid waste. It is an urgent problem to promote the resource utilization and harmless treatment of kitchen waste. The typical comprehensive treatment project of kitchen waste introduced in this paper consists of five parts: pretreatment system, anaerobic fermentation system, biogas purification and storage system, biogas residue and biogas liquid treatment system and deodorization system, covering an area of 19000 m2, with a total investment of RMB 99.78 million and a kitchen waste treatment scale of 200 t/d. The average biogas output is 7740 m3/d, in which the methane content is more than 60%. The reduction and recycling of kitchen waste was realized well. It can be taken as a reference for the disposal of kitchen waste in other cities in China.
2020, 38(8): 52-57.
doi: 10.13205/j.hjgc.202008009
Abstract:
In this study, crude glycerol, a by-product in the process of biodiesel preparation from waste cooking oil, was used as carbon source to produce microbial lipid by Rhodosporidium toruloides. Through the optimization, the optimized fermentation conditions were determined as follows: seed resuscitation time of 24 h, enrichment time of 10 h, inoculation rate of 6%, initial crude glycerin concentration of 60 g/L, ratio of carbon to nitrogen of 60, organic nitrogen ratio to total nitrogen of 75%, fermentation volume of 100 mL, fermentation temperature of 30 ℃ and fermentation time of 6 d. Under the optimal condition, lipid production and lipid yield rate reached 10.56 g/L and 0.229, respectively. Compared with inorganic ammonium sulfate, the addition of organic peptone significantly increased the lipid content and lipid production. The performance of biodiesel was estimated by measuring the fatty acid composition of lipid and using Hoekman equation, which met all of the standards of China, the United States and the European Union. This study can not only provide a new strategy for the reutilization of crude glycerol, but also provide a economical raw material for the production of biodiesel.
In this study, crude glycerol, a by-product in the process of biodiesel preparation from waste cooking oil, was used as carbon source to produce microbial lipid by Rhodosporidium toruloides. Through the optimization, the optimized fermentation conditions were determined as follows: seed resuscitation time of 24 h, enrichment time of 10 h, inoculation rate of 6%, initial crude glycerin concentration of 60 g/L, ratio of carbon to nitrogen of 60, organic nitrogen ratio to total nitrogen of 75%, fermentation volume of 100 mL, fermentation temperature of 30 ℃ and fermentation time of 6 d. Under the optimal condition, lipid production and lipid yield rate reached 10.56 g/L and 0.229, respectively. Compared with inorganic ammonium sulfate, the addition of organic peptone significantly increased the lipid content and lipid production. The performance of biodiesel was estimated by measuring the fatty acid composition of lipid and using Hoekman equation, which met all of the standards of China, the United States and the European Union. This study can not only provide a new strategy for the reutilization of crude glycerol, but also provide a economical raw material for the production of biodiesel.
2020, 38(8): 58-64.
doi: 10.13205/j.hjgc.202008010
Abstract:
In this paper, sludge and incineration plant leachate were used as feedstocks for anaerobic hydrogen fermentation by vial batch test, and influences of feedstock proportion and pH of leachate on stability of co-anaerobic fermentation and hydrogen production performance were investigated. The results showed that the sole leachate without adding sludge could also produce hydrogen during anaerobic fermentation. While, when the initial pH of leachate was 5.20, the maximum hydrogen production performance and maximum hydrogen production rate were obtained in co-anaerobic fermentation tests, with the addition proportion of leachate at 90%, and the corresponding peak values were 201.58 mL and 9.56 mL/h, respectively; when the initial pH of leachate was 4.47, the maximum hydrogen production performance occurred at the leachate adding proportion of 60% (57.73 mL) and then declined, while the maximum hydrogen production rate reached the peak value with the addition of 40% leachate, which was 5.11 mL/h.
In this paper, sludge and incineration plant leachate were used as feedstocks for anaerobic hydrogen fermentation by vial batch test, and influences of feedstock proportion and pH of leachate on stability of co-anaerobic fermentation and hydrogen production performance were investigated. The results showed that the sole leachate without adding sludge could also produce hydrogen during anaerobic fermentation. While, when the initial pH of leachate was 5.20, the maximum hydrogen production performance and maximum hydrogen production rate were obtained in co-anaerobic fermentation tests, with the addition proportion of leachate at 90%, and the corresponding peak values were 201.58 mL and 9.56 mL/h, respectively; when the initial pH of leachate was 4.47, the maximum hydrogen production performance occurred at the leachate adding proportion of 60% (57.73 mL) and then declined, while the maximum hydrogen production rate reached the peak value with the addition of 40% leachate, which was 5.11 mL/h.
2020, 38(8): 65-70.
doi: 10.13205/j.hjgc.202008011
Abstract:
This paper systematically investigated the evolution process, stage characteristics and achievement of China’s garbage sorting policy, which was an important basis for rational formulation and effective implementation of garbage classification policy and helpful to the establishment and implementation of garbage classification system and garbage classification system in the new era. It systematically analyzed the historical changes and development of garbage sorting policy since the founding of P.R. China. Overall, the development of China’s waste sorting policies experienced five stages: 1)namely the stage of classified collection enlightenment based on garbage recycling (1957—1991); 2)initial stage of enactment of laws and regulations on the classification of domestic waste (1992—1999); 3)classification criteria development stage based on garbage classification practices (2000—2015); 4)preparation stage of municipal solid waste classification system (2015—2016); 5)establishment and implementation of municipal solid waste classification system (since 2017). The results showed that China had basically formed a relatively complete waste sorting policy system in line with its present national conditions. The implementation of the garbage classification system could significantly improve the living environment, save resources and improve the level of social civilization, which was of great significance to promote green development and build a beautiful China.
This paper systematically investigated the evolution process, stage characteristics and achievement of China’s garbage sorting policy, which was an important basis for rational formulation and effective implementation of garbage classification policy and helpful to the establishment and implementation of garbage classification system and garbage classification system in the new era. It systematically analyzed the historical changes and development of garbage sorting policy since the founding of P.R. China. Overall, the development of China’s waste sorting policies experienced five stages: 1)namely the stage of classified collection enlightenment based on garbage recycling (1957—1991); 2)initial stage of enactment of laws and regulations on the classification of domestic waste (1992—1999); 3)classification criteria development stage based on garbage classification practices (2000—2015); 4)preparation stage of municipal solid waste classification system (2015—2016); 5)establishment and implementation of municipal solid waste classification system (since 2017). The results showed that China had basically formed a relatively complete waste sorting policy system in line with its present national conditions. The implementation of the garbage classification system could significantly improve the living environment, save resources and improve the level of social civilization, which was of great significance to promote green development and build a beautiful China.
2020, 38(8): 71-75.
doi: 10.13205/j.hjgc.202008012
Abstract:
Extracellular polymeric substances (EPSs) in excess sludge have great recycling value. However, the solutions of recycled EPSs afford the moisture contents of nearly 100% and therefore the dehydration of these solutions is an urgent problem. Forward osmosis (FO) membrane separation having advanteges of low membrane fouling, high concentration efficiency, and high concentration resistance, has become a novel low-energy dewatering technology. A novel dead-end FO concentration method was proposed and the FO dewatering of simulated EPS (sodium alginate) was investigated. The results showed that the decline rate of flux deceased when the active layer of FO membrane was towards the feed side; similar to external pressure drive, the cross flow mode could reduce FO membrane fouling and improve flux; the spacer, which was used for preventing the tensile deformation of the FO membrane, should be designed reasonably such as the appropriate holed ratio to reduce the flux decline; the mitigation of FO membrane fouling with Ca2+ addition was insignificant although it was reduced, different from the external pressure drive.
Extracellular polymeric substances (EPSs) in excess sludge have great recycling value. However, the solutions of recycled EPSs afford the moisture contents of nearly 100% and therefore the dehydration of these solutions is an urgent problem. Forward osmosis (FO) membrane separation having advanteges of low membrane fouling, high concentration efficiency, and high concentration resistance, has become a novel low-energy dewatering technology. A novel dead-end FO concentration method was proposed and the FO dewatering of simulated EPS (sodium alginate) was investigated. The results showed that the decline rate of flux deceased when the active layer of FO membrane was towards the feed side; similar to external pressure drive, the cross flow mode could reduce FO membrane fouling and improve flux; the spacer, which was used for preventing the tensile deformation of the FO membrane, should be designed reasonably such as the appropriate holed ratio to reduce the flux decline; the mitigation of FO membrane fouling with Ca2+ addition was insignificant although it was reduced, different from the external pressure drive.
2020, 38(8): 76-81.
doi: 10.13205/j.hjgc.202008013
Abstract:
Leachate, because of its complex and harmful components, which may accelerate pipes scaling and corrosion during its collection and transportation, poses potential risk to the environment. In this study, four typical pipe materials, including steel pipe, galvanized pipe, HDPE pipe and PVC pipe, were processed into experimental samples and immersed into leachate under aerobic and anaerobic conditions, investigate their corrosion resistance. Through the analysis of the samples weight changes, combined with the characterization of material properties, it was found that the scale formations and degree of corrosion were significantly related to the samples surface roughness. The rank of the materials was as HDPE > PVC > RC > TC. This study was expected to provide useful insights into the selection of pipe materials for leachate collection and transportation, ultimately to ensure the safe operation of the landfill.
Leachate, because of its complex and harmful components, which may accelerate pipes scaling and corrosion during its collection and transportation, poses potential risk to the environment. In this study, four typical pipe materials, including steel pipe, galvanized pipe, HDPE pipe and PVC pipe, were processed into experimental samples and immersed into leachate under aerobic and anaerobic conditions, investigate their corrosion resistance. Through the analysis of the samples weight changes, combined with the characterization of material properties, it was found that the scale formations and degree of corrosion were significantly related to the samples surface roughness. The rank of the materials was as HDPE > PVC > RC > TC. This study was expected to provide useful insights into the selection of pipe materials for leachate collection and transportation, ultimately to ensure the safe operation of the landfill.
2020, 38(8): 82-88.
doi: 10.13205/j.hjgc.202008014
Abstract:
Water pollution is a major restriction for the sustainable development of ecosystem in China, in which black and odorous water is a typical pollution. This article described the pollution situation of urban black and odorous water in China, and summarized the reasons and conditions of forming, as well as the mechanism of being black and smelly. Based on the current evaluation methodology and treatment techniques, we emphatically discussed the principles, pros. and cons., and applicability of the odor governing technology. Finally, further work suggestions were put forward on the perspective of remediation modes, public participation and long-term management, which will provide the valuable references for urban water environment management and water ecological maintenance.
Water pollution is a major restriction for the sustainable development of ecosystem in China, in which black and odorous water is a typical pollution. This article described the pollution situation of urban black and odorous water in China, and summarized the reasons and conditions of forming, as well as the mechanism of being black and smelly. Based on the current evaluation methodology and treatment techniques, we emphatically discussed the principles, pros. and cons., and applicability of the odor governing technology. Finally, further work suggestions were put forward on the perspective of remediation modes, public participation and long-term management, which will provide the valuable references for urban water environment management and water ecological maintenance.
2020, 38(8): 89-95.
doi: 10.13205/j.hjgc.202008015
Abstract:
In this paper, TiO2/GO composite photocatalysts were prepared through sol-gel method by using butyl titanate and different loads of graphene oxide as precursors, at the optimal calcination temperature (350℃). The structure and properties of TiO2/GO nanomaterials were characterized by SEM, XRD, Raman, FT-IR, TGA and BET. The degradation characteristic of humic acid (HA) in water by composite materials under UV light were analyzed. The results showed that the particle size of TiO2/GO composite catalyst was decreased, while the specific surface area was increased, the agglomeration effect was reduced and the photocatalytic efficiency was improved, with the increase of GO loading ratio. The two characteristic peaks of 1350 cm-1 and 1600 cm-1 in Raman spectrum indicated that the GO was successfully loaded in TiO2 nanomaterial, and the crystal type was mainly anatase. The composite material with 3%GO loaded performed best. When TiO2/3%GO dosage was 0.5 g/L and the initial HA concentration in water was 10 mg/L, the degradation rate under ultraviolet light reached 84.7% after 1 h of radiation, and the degradation rate constant was 0.0313 min-1.
In this paper, TiO2/GO composite photocatalysts were prepared through sol-gel method by using butyl titanate and different loads of graphene oxide as precursors, at the optimal calcination temperature (350℃). The structure and properties of TiO2/GO nanomaterials were characterized by SEM, XRD, Raman, FT-IR, TGA and BET. The degradation characteristic of humic acid (HA) in water by composite materials under UV light were analyzed. The results showed that the particle size of TiO2/GO composite catalyst was decreased, while the specific surface area was increased, the agglomeration effect was reduced and the photocatalytic efficiency was improved, with the increase of GO loading ratio. The two characteristic peaks of 1350 cm-1 and 1600 cm-1 in Raman spectrum indicated that the GO was successfully loaded in TiO2 nanomaterial, and the crystal type was mainly anatase. The composite material with 3%GO loaded performed best. When TiO2/3%GO dosage was 0.5 g/L and the initial HA concentration in water was 10 mg/L, the degradation rate under ultraviolet light reached 84.7% after 1 h of radiation, and the degradation rate constant was 0.0313 min-1.
2020, 38(8): 96-100,70.
doi: 10.13205/j.hjgc.202008016
Abstract:
The mechanism of hydrodynamic cavitation-acidification conditioning on sludge dewatering was studied. Specific resistance to filtration (SRF), sludge moisture content and capillary sunction time (CST) were the major indicators to evaluate the sludge dewatering performance. The content of polysaccharides and protein in extracellular polymeric substances (EPS) were determined, and sludge acidification extent and sludge electron microscopic image was analyzed at the same time. The results showed that the moisture content and SRF of the sludge decreased from 83.1% and 5.12×1011 m/kg, to 69.8% and 2.41×1011 m/kg, respectively, and the CST time decreased from 50 s to 20.8 s. The content of each EPS component decreased significantly. The acidification changed the dewatering property of the sludge by affecting the polysaccharide and protein content in the S-EPS and LB-EPS of the sludge. The sludge had the best dewatering effect at pH=3. In summary, hydrodynamic cavitation-acidification conditioning could greatly enhance the dewatering performance of sludge, and had great application value in practical engineering.
The mechanism of hydrodynamic cavitation-acidification conditioning on sludge dewatering was studied. Specific resistance to filtration (SRF), sludge moisture content and capillary sunction time (CST) were the major indicators to evaluate the sludge dewatering performance. The content of polysaccharides and protein in extracellular polymeric substances (EPS) were determined, and sludge acidification extent and sludge electron microscopic image was analyzed at the same time. The results showed that the moisture content and SRF of the sludge decreased from 83.1% and 5.12×1011 m/kg, to 69.8% and 2.41×1011 m/kg, respectively, and the CST time decreased from 50 s to 20.8 s. The content of each EPS component decreased significantly. The acidification changed the dewatering property of the sludge by affecting the polysaccharide and protein content in the S-EPS and LB-EPS of the sludge. The sludge had the best dewatering effect at pH=3. In summary, hydrodynamic cavitation-acidification conditioning could greatly enhance the dewatering performance of sludge, and had great application value in practical engineering.
2020, 38(8): 101-104.
doi: 10.13205/j.hjgc.202008017
Abstract:
In-situ microbiological technology is an innovative way for fast, complete and efficient destruction of organics by activating indigenous microorganisms in water bodies. Field application results in the Liangma River indicated that COD and TP of the downstream decreased obviously; the change in NH3-N was not obvious because of the relatively low background value. When the system worked for 60 days, the data indicated that species in downstream were abundant with a high biodiversity. The species of phytoplankton and zoobenthos in downstream also possessed higher species richness than that in upstream. In-situ microbiological technology can not only improve water quality and the sediment, but also replenish biological diversity, and consequently enhance the water's self-purification ability.
In-situ microbiological technology is an innovative way for fast, complete and efficient destruction of organics by activating indigenous microorganisms in water bodies. Field application results in the Liangma River indicated that COD and TP of the downstream decreased obviously; the change in NH3-N was not obvious because of the relatively low background value. When the system worked for 60 days, the data indicated that species in downstream were abundant with a high biodiversity. The species of phytoplankton and zoobenthos in downstream also possessed higher species richness than that in upstream. In-situ microbiological technology can not only improve water quality and the sediment, but also replenish biological diversity, and consequently enhance the water's self-purification ability.
2020, 38(8): 105-112,135.
doi: 10.13205/j.hjgc.202008018
Abstract:
In order to study the ecological restoration effect of eutrophic water by aquatic plants, nine aquatic macrophytes, including Phragmites communis, Iris pseudacorus L., Canna indica L., Lythrum salicaria L., Myriophyllum verticillatum L., Hydrilla verticillata, Potamogeton distinctus, Hydrocotyle vulgaris and Nymphaea L. were selected to investigate their purification effect. The results showed that all of the nine plants exhibited obvious purification effects on eutrophic water, the removal rates of TN, TP, NH4+-N and COD could achieve 49.97%~97.89%, 75.66%~99.92%, 55.91%~95.87% and 57.19%~67.87 respectively. According to the result of laboratory scale experiment, the demonstration water restoration project was designed and applied in Chanel C, Dishui Lake. The reults showed that the concentration of TN, TP, NH4+-N and CODMn were decreased by 25.87%, 56.60%, 18.42% and 29.25% after ecological restoration, and the value of chlorophyll was decreased by 60.1% after restoration. The dissolved oxygen and transparency was increased by 45.73% and 28.68%, respectively. Meanwhile, the demonstration area was transformed from medium level eutrophication to mild level after restoration, which indicated that the application of ecological restoration by aquatic plants exhibited significant performance in water purification.
In order to study the ecological restoration effect of eutrophic water by aquatic plants, nine aquatic macrophytes, including Phragmites communis, Iris pseudacorus L., Canna indica L., Lythrum salicaria L., Myriophyllum verticillatum L., Hydrilla verticillata, Potamogeton distinctus, Hydrocotyle vulgaris and Nymphaea L. were selected to investigate their purification effect. The results showed that all of the nine plants exhibited obvious purification effects on eutrophic water, the removal rates of TN, TP, NH4+-N and COD could achieve 49.97%~97.89%, 75.66%~99.92%, 55.91%~95.87% and 57.19%~67.87 respectively. According to the result of laboratory scale experiment, the demonstration water restoration project was designed and applied in Chanel C, Dishui Lake. The reults showed that the concentration of TN, TP, NH4+-N and CODMn were decreased by 25.87%, 56.60%, 18.42% and 29.25% after ecological restoration, and the value of chlorophyll was decreased by 60.1% after restoration. The dissolved oxygen and transparency was increased by 45.73% and 28.68%, respectively. Meanwhile, the demonstration area was transformed from medium level eutrophication to mild level after restoration, which indicated that the application of ecological restoration by aquatic plants exhibited significant performance in water purification.
2020, 38(8): 113-118,57.
doi: 10.13205/j.hjgc.202008019
Abstract:
In this paper, the degradation effect of heterogeneous activating peroxydisulfate and peroxymonosulfate by GAC on the azo dye AO Ⅱ in water were studied. The effects of persulfate dosage, activated carbon dosage, solution pH and inorganic anion on the degradation rate of AO Ⅱ were investigated. The reasons for the difference in the degradation of dyes by different persulfates were studied. When the azo dye concentration was 20 mg/L and the molar ratio of persulfate to acid orange Ⅱ was 200∶1, the degradation rate of dyes was the highest. Degradation effect got better when adding peroxydisulfate, and the solution was in acidic condition, and the increase of granular activated carbon was conductive to the removal of dyes; the addition of inorganic anions had an inhibitory effect on degradation of AO Ⅱ; free radicals generated on the surface of activated carbon played an important role in the degradation of dye.
In this paper, the degradation effect of heterogeneous activating peroxydisulfate and peroxymonosulfate by GAC on the azo dye AO Ⅱ in water were studied. The effects of persulfate dosage, activated carbon dosage, solution pH and inorganic anion on the degradation rate of AO Ⅱ were investigated. The reasons for the difference in the degradation of dyes by different persulfates were studied. When the azo dye concentration was 20 mg/L and the molar ratio of persulfate to acid orange Ⅱ was 200∶1, the degradation rate of dyes was the highest. Degradation effect got better when adding peroxydisulfate, and the solution was in acidic condition, and the increase of granular activated carbon was conductive to the removal of dyes; the addition of inorganic anions had an inhibitory effect on degradation of AO Ⅱ; free radicals generated on the surface of activated carbon played an important role in the degradation of dye.
2020, 38(8): 119-124.
doi: 10.13205/j.hjgc.202008020
Abstract:
In this study, biochars were prepared by sewage sludge at 300, 400, 500, 600℃, respectively. The influence of preparation temperature on Cr(Ⅵ) adsorption by biochar was investigated through single factor static adsorption experiment. The results showed the positive effect of Cr(Ⅵ) adsorption along with increase of preparation temperature under 500 ℃, and negligible change within the preparation temperature range of 500~600 ℃. Differences of surface morphology and functional groups of biochars prepared by various temperature were characterized by SEM (scanning electron microscope), BET (Brunauer Emmett Teller) and FTIR (Fourier transform infrared), which were considered as the capital factor for diversity of adsorption. The results of isothermal model and kinetic fitting demostrated that the Cr(Ⅵ) adsorption by biochars as modality of monomolecular layer, physical-chemical composite adsorption; the experimental results showed that the optimal preparation temperature was 500 ℃. The theoretical adsorption capacity for Cr(Ⅵ) of biochar prepared under the condition of 500 ℃ reached 7.93 mg/g. The research conclusion could provide theoretical basis and practical support for recycling of municipal sludge.
In this study, biochars were prepared by sewage sludge at 300, 400, 500, 600℃, respectively. The influence of preparation temperature on Cr(Ⅵ) adsorption by biochar was investigated through single factor static adsorption experiment. The results showed the positive effect of Cr(Ⅵ) adsorption along with increase of preparation temperature under 500 ℃, and negligible change within the preparation temperature range of 500~600 ℃. Differences of surface morphology and functional groups of biochars prepared by various temperature were characterized by SEM (scanning electron microscope), BET (Brunauer Emmett Teller) and FTIR (Fourier transform infrared), which were considered as the capital factor for diversity of adsorption. The results of isothermal model and kinetic fitting demostrated that the Cr(Ⅵ) adsorption by biochars as modality of monomolecular layer, physical-chemical composite adsorption; the experimental results showed that the optimal preparation temperature was 500 ℃. The theoretical adsorption capacity for Cr(Ⅵ) of biochar prepared under the condition of 500 ℃ reached 7.93 mg/g. The research conclusion could provide theoretical basis and practical support for recycling of municipal sludge.
2020, 38(8): 125-130,51.
doi: 10.13205/j.hjgc.202008021
Abstract:
A compound materials (FP) with a combination of Portland cement and efficient heavy metal stabilization material was used to solidify and stabilize river sediment containing heavy metals. In this paper, we set three FP dosages of 10%, 20%, 30%, three curing times of 7, 28, 42 d, and selected Portland cement as the control (CK). The compressive strength and leaching concentration were selected as indicators to test the solidifying and stabilizing effect of FP. The results showed that compared to the direct leaching of sediment, the leaching concentration of As in the sediment was reduced by more than 93%, that of Pb was reduced by 82.5%~97.68% under different FP dosages after 28 days. The leaching concentration of Cu and Zn reached the lowest value when the FP dosage was 30% and curing time was 42 days, which were 60.97% and 89.07% lower than the direct leaching of the sediment, respectively. Under different treatments, the leaching concentration of Cu and As in FP group was all significantly lower than that in CK (P<0.01); that of Zn in FP group was significantly lower than in CK after 42 days under 30% FP dosage (P<0.05). With the dosage of FP or the curing time increased, compressive strength of the solidified products was also significantly enhanced (P<0.05). Compressive strength of the solidified products of FP was significantly higher than that of CK (P<0.05) after 42 days, and when the dosage of FP increased to 30%, the compressive strength reached 2.1 MPa.
A compound materials (FP) with a combination of Portland cement and efficient heavy metal stabilization material was used to solidify and stabilize river sediment containing heavy metals. In this paper, we set three FP dosages of 10%, 20%, 30%, three curing times of 7, 28, 42 d, and selected Portland cement as the control (CK). The compressive strength and leaching concentration were selected as indicators to test the solidifying and stabilizing effect of FP. The results showed that compared to the direct leaching of sediment, the leaching concentration of As in the sediment was reduced by more than 93%, that of Pb was reduced by 82.5%~97.68% under different FP dosages after 28 days. The leaching concentration of Cu and Zn reached the lowest value when the FP dosage was 30% and curing time was 42 days, which were 60.97% and 89.07% lower than the direct leaching of the sediment, respectively. Under different treatments, the leaching concentration of Cu and As in FP group was all significantly lower than that in CK (P<0.01); that of Zn in FP group was significantly lower than in CK after 42 days under 30% FP dosage (P<0.05). With the dosage of FP or the curing time increased, compressive strength of the solidified products was also significantly enhanced (P<0.05). Compressive strength of the solidified products of FP was significantly higher than that of CK (P<0.05) after 42 days, and when the dosage of FP increased to 30%, the compressive strength reached 2.1 MPa.
2020, 38(8): 131-135.
doi: 10.13205/j.hjgc.202008022
Abstract:
In order to improve the removal of total nitrogen from pharmaceutical wastewater, the SBBR based on fibrous fillers was used to treat the actual pharmaceutical wastewater. The test of start-up and domestication lasted for 99 days, and with the initial ammonia nitrogen concentration of (200±20) mg/L in the wastewater, the total nitrogen removal rate of the system was kept at 97% above, without addition of carbon source. When the carbon nitrogen ratio was at 3, the system could not realize advanced nitrogen removal. The denitrification efficiency of the wastewater could be improved by increasing carbon nitrogen ratio. When the carbon nitrogen ratio in wastewater was at 5, the system achieved advanced nitrogen removal. Due to the large quantity of biofilms on the fibrous fillers, the advanced nitrogen removal of SBBR was achieved after the end of aeration. The denitrification pathway gradually changed from SND & endogenous denitrification to SND. The final operation mode was also final determined as feed-stir-aeration-settle-decant.
In order to improve the removal of total nitrogen from pharmaceutical wastewater, the SBBR based on fibrous fillers was used to treat the actual pharmaceutical wastewater. The test of start-up and domestication lasted for 99 days, and with the initial ammonia nitrogen concentration of (200±20) mg/L in the wastewater, the total nitrogen removal rate of the system was kept at 97% above, without addition of carbon source. When the carbon nitrogen ratio was at 3, the system could not realize advanced nitrogen removal. The denitrification efficiency of the wastewater could be improved by increasing carbon nitrogen ratio. When the carbon nitrogen ratio in wastewater was at 5, the system achieved advanced nitrogen removal. Due to the large quantity of biofilms on the fibrous fillers, the advanced nitrogen removal of SBBR was achieved after the end of aeration. The denitrification pathway gradually changed from SND & endogenous denitrification to SND. The final operation mode was also final determined as feed-stir-aeration-settle-decant.
2020, 38(8): 136-141.
doi: 10.13205/j.hjgc.202008023
Abstract:
Aiming at the problems of low electrocatalytic performance and large power consumption of particle electrodes, metal-supported activated carbon particle electrodes were prepared by impregnation with columnar activity (AC) as the carrier. The optimal preparation conditions were explored by orthogonal experiments, and Bohem Back Titration Method and SEM were applied for characterization of modified activated carbon. The orthogonal experiments showed that the electrocatalytic performance of the particle electrode was affected by the impregnation time more than by the impregnation concentration, roasting time, and roasting temperature. Morphology of particle electrodes varied greatly under different preparation condition. The particle electrode immersed in a 0.1 mol/L immersion liquid for 12 h and then calcined at 400 ℃ for 4 h, using in the three-dimensional electrode reactor, had a removal rate of 86% for reactive brilliant red X-3B;the COD removal rate reached 66%. Compared with original activated carbon, the dye removal rate increase by 5.29 percents, the COD removal rate increase by 10.12 percents, and the energy consumption decrease by 13%. Ni/AC particle electrode could improve the electrocatalytic performance of metal modified activated carbon particles and reduce energy consumption.
Aiming at the problems of low electrocatalytic performance and large power consumption of particle electrodes, metal-supported activated carbon particle electrodes were prepared by impregnation with columnar activity (AC) as the carrier. The optimal preparation conditions were explored by orthogonal experiments, and Bohem Back Titration Method and SEM were applied for characterization of modified activated carbon. The orthogonal experiments showed that the electrocatalytic performance of the particle electrode was affected by the impregnation time more than by the impregnation concentration, roasting time, and roasting temperature. Morphology of particle electrodes varied greatly under different preparation condition. The particle electrode immersed in a 0.1 mol/L immersion liquid for 12 h and then calcined at 400 ℃ for 4 h, using in the three-dimensional electrode reactor, had a removal rate of 86% for reactive brilliant red X-3B;the COD removal rate reached 66%. Compared with original activated carbon, the dye removal rate increase by 5.29 percents, the COD removal rate increase by 10.12 percents, and the energy consumption decrease by 13%. Ni/AC particle electrode could improve the electrocatalytic performance of metal modified activated carbon particles and reduce energy consumption.
2020, 38(8): 142-146.
doi: 10.13205/j.hjgc.202008024
Abstract:
In order to enhance the nitrogen removal performance of completely autotrophic nitrogen removal over nitrite (CANON) process, membrane bioreactors (MBRs) were constructed to start the CANON process in this study. Static magnetic field (MF) was applied to enhance the CANON process, and the nitrogen removal performance and the mechanism were analyzed. The results showed that MF with suitable intensity enhanced the nitrogen removal rate (NRR) and shortened the start-up period during the CANON process. The average NRR during the late period reached 49.5 g/(m3·d) with the exposure to MF, which was 1.45 times higher than the control. At low temperature, the CANON process could keep high activity with the exposure to MF, and the average NRR was 2.88 times of the control. The MF could stimulate the synthesis and secretion of extracellular polymer (EPS) of sludge, and enhance the contents of protein in EPS. Meanwhile the zeta potential of the mixture in the reactor decreased due to the application of MF, which was conducive to the aggregation of the activated sludge. The oxygen concentration gradient in the flocs favored the coexistence of different microorganisms during CANON process, resulting in the enhancement of nitrogen removal.
In order to enhance the nitrogen removal performance of completely autotrophic nitrogen removal over nitrite (CANON) process, membrane bioreactors (MBRs) were constructed to start the CANON process in this study. Static magnetic field (MF) was applied to enhance the CANON process, and the nitrogen removal performance and the mechanism were analyzed. The results showed that MF with suitable intensity enhanced the nitrogen removal rate (NRR) and shortened the start-up period during the CANON process. The average NRR during the late period reached 49.5 g/(m3·d) with the exposure to MF, which was 1.45 times higher than the control. At low temperature, the CANON process could keep high activity with the exposure to MF, and the average NRR was 2.88 times of the control. The MF could stimulate the synthesis and secretion of extracellular polymer (EPS) of sludge, and enhance the contents of protein in EPS. Meanwhile the zeta potential of the mixture in the reactor decreased due to the application of MF, which was conducive to the aggregation of the activated sludge. The oxygen concentration gradient in the flocs favored the coexistence of different microorganisms during CANON process, resulting in the enhancement of nitrogen removal.
2020, 38(8): 147-153.
doi: 10.13205/j.hjgc.202008025
Abstract:
Membrane bioreactor (MBR) is a wastewater treatment process combining membrane separation technology with activated sludge process. The high removal efficiency of MBR makes it widely used, but the problems of membrane blockage and membrane pollution hinder the further popularization of MBR process. Powder activated carbon (PAC) has a high specific surface area, and strong adsorption capacity that can effectively alleviate the membrane blockage and membrane pollution during operation. By summing up the research progress of the carbon membrane bioreactor (PAC-MBR) in recent years, the influencing factors (pH, hydraulic residence time, sludge residence time, aeration volume, sludge concentration and inlet water quality) affecting MBR process were analyzed, the removal of ammonia nitrogen, BOD, COD, TOC and TN were summarized, the process effect of turbidity by PAC-MBR combined process on wastewater, and the effects of PAC-MBR process on microbial extracellular polymer (EPS), membrane contamination, TMP and microorganisms were summarized.
Membrane bioreactor (MBR) is a wastewater treatment process combining membrane separation technology with activated sludge process. The high removal efficiency of MBR makes it widely used, but the problems of membrane blockage and membrane pollution hinder the further popularization of MBR process. Powder activated carbon (PAC) has a high specific surface area, and strong adsorption capacity that can effectively alleviate the membrane blockage and membrane pollution during operation. By summing up the research progress of the carbon membrane bioreactor (PAC-MBR) in recent years, the influencing factors (pH, hydraulic residence time, sludge residence time, aeration volume, sludge concentration and inlet water quality) affecting MBR process were analyzed, the removal of ammonia nitrogen, BOD, COD, TOC and TN were summarized, the process effect of turbidity by PAC-MBR combined process on wastewater, and the effects of PAC-MBR process on microbial extracellular polymer (EPS), membrane contamination, TMP and microorganisms were summarized.
2020, 38(8): 154-159.
doi: 10.13205/j.hjgc.202008026
Abstract:
In this study, the MFC-MBR integrated system was constructed by coupling the microbial fuel cell (MFC) with the membrane bioreactor(MBR). Based on the MFC-MBR integrated system, the effects of MFC micro-electric field on the distribution and migration of soluble microbial products (SMP) and extracellular polymer (EPS) around MBR membrane modules were studied. The results showed that the MFC-MBR integrated system could provide a maximum output voltage of 0.78 V. Under the action of this electric field, the time required for MBR’s transmembrane pressure difference (TMP) to reach 30 kPa was 14 d, which was 6 days longer than that without external power. At the same time, the scanning electron micrograph showed that the film surface covering was less than the electric field in the presence of an electric field after long-term operation. By detecting and analyzing SMP and EPS around the MBR membrane module, it was found that under the action of external electric field, SMP and loose extracellular polymer (LB-EPS) would be far away from the membrane module, and its concentration would increase with the distance from the membrane module. However, TB-EPS was distributed evenly, which relfected that TB-EPS could not be affected by the electric field. The results of this study demonstrated that SMP and LB-EPS could move away from the surface of MBR membrane under the action of micro electric field, which could effectively reduce the pollution of MBR membrane, so as to reduce operating cost for MBR.
In this study, the MFC-MBR integrated system was constructed by coupling the microbial fuel cell (MFC) with the membrane bioreactor(MBR). Based on the MFC-MBR integrated system, the effects of MFC micro-electric field on the distribution and migration of soluble microbial products (SMP) and extracellular polymer (EPS) around MBR membrane modules were studied. The results showed that the MFC-MBR integrated system could provide a maximum output voltage of 0.78 V. Under the action of this electric field, the time required for MBR’s transmembrane pressure difference (TMP) to reach 30 kPa was 14 d, which was 6 days longer than that without external power. At the same time, the scanning electron micrograph showed that the film surface covering was less than the electric field in the presence of an electric field after long-term operation. By detecting and analyzing SMP and EPS around the MBR membrane module, it was found that under the action of external electric field, SMP and loose extracellular polymer (LB-EPS) would be far away from the membrane module, and its concentration would increase with the distance from the membrane module. However, TB-EPS was distributed evenly, which relfected that TB-EPS could not be affected by the electric field. The results of this study demonstrated that SMP and LB-EPS could move away from the surface of MBR membrane under the action of micro electric field, which could effectively reduce the pollution of MBR membrane, so as to reduce operating cost for MBR.
2020, 38(8): 160-166,173.
doi: 10.13205/j.hjgc.202008027
Abstract:
Efficient and high-precision simulation of the process of non-point source pollution and mastering the law of non-point source pollution is one of the most direct and effective ways to study non-point source pollution, and also an effective way to manage and control non-point source pollution. Based on this, this paper proposed a numerical model that fully coupled two-dimensional hydro-hydrodynamic and pollutant transport processes. It used the second-order Godunov format finite volume method to solve the problem, and used GPU acceleration technology to improve computing efficiency. The results showed that, under ideal conditions, the average relative error between the numerical and analytical solutions was 2.5%. The transport processes of urban surface source pollution and agricultural non-point source pollution with different areas and accuracy were simulated, and the results showed that the transport laws of the two were consistent with the actual physical process. The total simulation time was 7200 s. The simulation of urban surface source pollution took only 186 s; the simulation of agricultural non-point source pollution took 1169 s, and the calculation efficiency was significantly improved. In summary, the GAST model could not only achieve high-precision simulation of different underlying surface source pollution simulations, but also significantly improve the simulation efficiency, and provide basic support for future non-point source pollution control and prevention.
Efficient and high-precision simulation of the process of non-point source pollution and mastering the law of non-point source pollution is one of the most direct and effective ways to study non-point source pollution, and also an effective way to manage and control non-point source pollution. Based on this, this paper proposed a numerical model that fully coupled two-dimensional hydro-hydrodynamic and pollutant transport processes. It used the second-order Godunov format finite volume method to solve the problem, and used GPU acceleration technology to improve computing efficiency. The results showed that, under ideal conditions, the average relative error between the numerical and analytical solutions was 2.5%. The transport processes of urban surface source pollution and agricultural non-point source pollution with different areas and accuracy were simulated, and the results showed that the transport laws of the two were consistent with the actual physical process. The total simulation time was 7200 s. The simulation of urban surface source pollution took only 186 s; the simulation of agricultural non-point source pollution took 1169 s, and the calculation efficiency was significantly improved. In summary, the GAST model could not only achieve high-precision simulation of different underlying surface source pollution simulations, but also significantly improve the simulation efficiency, and provide basic support for future non-point source pollution control and prevention.
2020, 38(8): 167-173.
doi: 10.13205/j.hjgc.202008028
Abstract:
The construction of the sponge city is aimed to restore the natural storage capacity of the city and improve the ecological environment and urban resilience. In this paper, the SWMM of international eco-business district in Songjiang district in Shanghai was established to evaluate the effect of sponge city construction on regional runoff control and pollution load control. The results showed that: compared with the traditional development mode, the construction of sponge city could significantly store rainfall, then reduce regional runoff, also reduce the pollution load into the river, and effectively reduce the pressure of regional drainage and water environment. The total runoff of sponge city was reduced by 40.8%, 39.5%, 37.0% and 35.8%, respectively, after 2 hours rainfall with recurrence period of 3-year, 5-year, 20-year and 50-year. The reduction of TSS, COD, TN and TP was 36.3%, 39.4%, 32.9% and 47.6%, respectively, after 2 hours rainfall with 5-year recurrence period.
The construction of the sponge city is aimed to restore the natural storage capacity of the city and improve the ecological environment and urban resilience. In this paper, the SWMM of international eco-business district in Songjiang district in Shanghai was established to evaluate the effect of sponge city construction on regional runoff control and pollution load control. The results showed that: compared with the traditional development mode, the construction of sponge city could significantly store rainfall, then reduce regional runoff, also reduce the pollution load into the river, and effectively reduce the pressure of regional drainage and water environment. The total runoff of sponge city was reduced by 40.8%, 39.5%, 37.0% and 35.8%, respectively, after 2 hours rainfall with recurrence period of 3-year, 5-year, 20-year and 50-year. The reduction of TSS, COD, TN and TP was 36.3%, 39.4%, 32.9% and 47.6%, respectively, after 2 hours rainfall with 5-year recurrence period.
2020, 38(8): 174-179,81.
doi: 10.13205/j.hjgc.202008029
Abstract:
Based on commercial anatase TiO2, three catalysts were prepared using different chelating agents of vanadium salt by wet impregnation, and then studied the catalytic performances of SCR. Characterizing measures including H2-TPR, N2 adsorption-desorption with BET method, NH3-TPD, XRD, Raman, and UV-Vis DRS were conducted to investigate the physicochemical properties of V2O5/TiO2 catalysts. It was found that the diverse chelating agents of vanadium salt had great impact on the valence states of vanadium and pH value of precursor solution. Nonetheless, within the test temperature ranges, there were no distinction on the SCR activity and N2 selectivity. By means of disparate characterization methods, it was concluded that there was almost no difference among those three catalysts on specific surface area, pore structure, polymerization degree of vanadium oxides on the surface of TiO2, H2 activation energy and surface acidity. Meanwhile, the valence states of vanadium and pH value of precursor solution could not affect the catalytic performances of V2O5/TiO2 SCR catalysts.
Based on commercial anatase TiO2, three catalysts were prepared using different chelating agents of vanadium salt by wet impregnation, and then studied the catalytic performances of SCR. Characterizing measures including H2-TPR, N2 adsorption-desorption with BET method, NH3-TPD, XRD, Raman, and UV-Vis DRS were conducted to investigate the physicochemical properties of V2O5/TiO2 catalysts. It was found that the diverse chelating agents of vanadium salt had great impact on the valence states of vanadium and pH value of precursor solution. Nonetheless, within the test temperature ranges, there were no distinction on the SCR activity and N2 selectivity. By means of disparate characterization methods, it was concluded that there was almost no difference among those three catalysts on specific surface area, pore structure, polymerization degree of vanadium oxides on the surface of TiO2, H2 activation energy and surface acidity. Meanwhile, the valence states of vanadium and pH value of precursor solution could not affect the catalytic performances of V2O5/TiO2 SCR catalysts.
2020, 38(8): 180-187.
doi: 10.13205/j.hjgc.202008030
Abstract:
Odorous volatile organic compounds (VOCs) from large-scale livestock and poultry farms,characterized by low olfactory threshold, are the important parts of the odorous gas pollutants. The odour nuisance is associated with danger and may be the cause of negative psychosomatic symptoms of humans and animals,as well as the environment.The objective of this article was to introduce the production mechanism and harm of main odorous VOCs, and to provide a systematic review on the research progress of source reduction and end treatment technologies for odorous VOCs, as well as to summarize available data on VOCs reduction effectiveness of promising technologies.
Odorous volatile organic compounds (VOCs) from large-scale livestock and poultry farms,characterized by low olfactory threshold, are the important parts of the odorous gas pollutants. The odour nuisance is associated with danger and may be the cause of negative psychosomatic symptoms of humans and animals,as well as the environment.The objective of this article was to introduce the production mechanism and harm of main odorous VOCs, and to provide a systematic review on the research progress of source reduction and end treatment technologies for odorous VOCs, as well as to summarize available data on VOCs reduction effectiveness of promising technologies.
2020, 38(8): 188-194,200.
doi: 10.13205/j.hjgc.202008031
Abstract:
On the basis of the activity level data of VOCs pollution sources in a district around Tianjin, corresponding emission factors were selected to construct a small scale VOCs emission list of 0.5 km×0.5 km in 2017. The results showed that in 2017, 3563.35 tons of VOCs were emitted in a district around Tianjin. Road mobile sources dominated by small buses, light trucks and heavy trucks contributed 32.14%, solvent sources dominated by industrial solvents contributed 31.05%, and process sources dominated by steel and non-metallic mineral products contributed 21.57%. According to the spatial distribution results, it was mainly distributed in the areas with dense trunk roads, coating manufacturing, iron and non-metallic mineral products. The top three towns were Gegu town, Xianshuigu town and Beizhakou town, with the share rates of 21.47%, 19.17% and 13.82% respectively. There were still some uncertain factors in this list, activity level data such as road traffic flow need to be further detailed, and localization research on emission factors should be further carried out, to provide scientific basis for the formulation of regional pollution prevention and control strategies.
On the basis of the activity level data of VOCs pollution sources in a district around Tianjin, corresponding emission factors were selected to construct a small scale VOCs emission list of 0.5 km×0.5 km in 2017. The results showed that in 2017, 3563.35 tons of VOCs were emitted in a district around Tianjin. Road mobile sources dominated by small buses, light trucks and heavy trucks contributed 32.14%, solvent sources dominated by industrial solvents contributed 31.05%, and process sources dominated by steel and non-metallic mineral products contributed 21.57%. According to the spatial distribution results, it was mainly distributed in the areas with dense trunk roads, coating manufacturing, iron and non-metallic mineral products. The top three towns were Gegu town, Xianshuigu town and Beizhakou town, with the share rates of 21.47%, 19.17% and 13.82% respectively. There were still some uncertain factors in this list, activity level data such as road traffic flow need to be further detailed, and localization research on emission factors should be further carried out, to provide scientific basis for the formulation of regional pollution prevention and control strategies.
2020, 38(8): 195-200.
doi: 10.13205/j.hjgc.202008032
Abstract:
Biomass energy is an important part of energy structure in the future, and crop straw is one of the main sources of biomass energy resources, thus its energy utilization technology deserves exploration and promotion. In order to evaluate the resource utilization, application benefits, economic benefits, environmental benefits and social benefits of straw energy utilization technology, based on the existing literature, this paper reviewed the research status of evaluation methods commonly used in straw energy utilization technology, analyzed the advantages and disadvantages of various technical evaluation methods, summarized the evaluation scope of different methods. It also proposed the method suitable for straw energy utilization technology, that was, the comprehensive evaluation method combining life cycle assessment and analytic hierarchy process. According to the existing literature references, the evaluation index system was established, which laid a foundation for the evaluation of the utilization model of straw energy utilization technology.
Biomass energy is an important part of energy structure in the future, and crop straw is one of the main sources of biomass energy resources, thus its energy utilization technology deserves exploration and promotion. In order to evaluate the resource utilization, application benefits, economic benefits, environmental benefits and social benefits of straw energy utilization technology, based on the existing literature, this paper reviewed the research status of evaluation methods commonly used in straw energy utilization technology, analyzed the advantages and disadvantages of various technical evaluation methods, summarized the evaluation scope of different methods. It also proposed the method suitable for straw energy utilization technology, that was, the comprehensive evaluation method combining life cycle assessment and analytic hierarchy process. According to the existing literature references, the evaluation index system was established, which laid a foundation for the evaluation of the utilization model of straw energy utilization technology.
2020, 38(8): 201-206.
doi: 10.13205/j.hjgc.202008033
Abstract:
In order to study the effect of liquid microbial fertilizer prepared by digesting biogas slurry of food waste on soil physical and chemical properties, winter wheat and rice soils of typical crops in northern China were analyzed during a whole growth cycle of crops. The results showed that the liquid bacterial fertilizer prepared by digesting biogas slurry from food waste significantly increased the effective nitrogen and phosphorus contents in winter wheat and rice soil. The optimum application rate of liquid bacterial fertilizer for winter wheat soil was 500 L/mu (1 mu=666.67 m2). The effective phosphorus content in the soil increased to 94.00 mg/kg, and the maximum increase was 81.12%. The maximum available nitrogen content increased to 1673.00 mg/kg, with the maximum increase of 84.88%. The optimum application rate of liquid bacterial fertilizer for rice soil was 400 L/mu. The effective phosphorus content in the soil increased to 220.80 mg/kg, and the maximum increase was 137.22%. The maximum available nitrogen content increased to 1140.00 mg/kg, with the maximum increase of 127.07%. There was a slight accumulation of soluble total salt and Cl- content in winter wheat and rice soils. Through RDA analysis, the total phosphorus, total nitrogen, Cl-, etc., in winter wheat soil and rice soil were positively correlated with the dosage of liquid bacterial fertilizer. This result indicated that liquid bacterial fertilizer promoted the increase of nutrients. The application of liquid waste fertilizer prepared by digesting biogas slurry of food waste is of great significance in improving the organic components of crop soil and soil fertility.
In order to study the effect of liquid microbial fertilizer prepared by digesting biogas slurry of food waste on soil physical and chemical properties, winter wheat and rice soils of typical crops in northern China were analyzed during a whole growth cycle of crops. The results showed that the liquid bacterial fertilizer prepared by digesting biogas slurry from food waste significantly increased the effective nitrogen and phosphorus contents in winter wheat and rice soil. The optimum application rate of liquid bacterial fertilizer for winter wheat soil was 500 L/mu (1 mu=666.67 m2). The effective phosphorus content in the soil increased to 94.00 mg/kg, and the maximum increase was 81.12%. The maximum available nitrogen content increased to 1673.00 mg/kg, with the maximum increase of 84.88%. The optimum application rate of liquid bacterial fertilizer for rice soil was 400 L/mu. The effective phosphorus content in the soil increased to 220.80 mg/kg, and the maximum increase was 137.22%. The maximum available nitrogen content increased to 1140.00 mg/kg, with the maximum increase of 127.07%. There was a slight accumulation of soluble total salt and Cl- content in winter wheat and rice soils. Through RDA analysis, the total phosphorus, total nitrogen, Cl-, etc., in winter wheat soil and rice soil were positively correlated with the dosage of liquid bacterial fertilizer. This result indicated that liquid bacterial fertilizer promoted the increase of nutrients. The application of liquid waste fertilizer prepared by digesting biogas slurry of food waste is of great significance in improving the organic components of crop soil and soil fertility.
2020, 38(8): 207-212,146.
doi: 10.13205/j.hjgc.202008034
Abstract:
Oily sludge, the featured important solid waste in the petroleum industry, is a (semi-)solid composite composed of petroleum hydrocarbons, water, particulate matters and other harmful substances (such as heavy metals), classified as hazardous waste due to the toxicity and ignitability. The annual output of oily sludge in China is up to 5 million tons, including 15%~50% of petroleum hydrocarbons. If oily sludge is treated improperly, it will not only pose a huge threat to the ecosystem, but also cause waste of non-renewable resources. Therefore, the disposal of oily sludge should balance harmless treatment and resource utilization. Based on the composition, characteristics and hazards of oily sludge, this work introduced the separation technologies of oil resources (centrifugation, solvent extraction, pyrolysis) and residual oily residue harmless treatment methods (incineration, solidification stabilization, biological treatment). In general, the integrated treatment technology routine of oily sludge is: 1) reduce the moisture content and increase the oil concentration by pretreatment; 2) recover the petroleum hydrocarbons in the oily sludge by oil separation methods; 3) treat the oil-bearing residue harmlessly finally. Meanwhile, the characteristics of each method and the research progress were discussed, and suggestions for the development of oily sludge treatment technology were aproposed.
Oily sludge, the featured important solid waste in the petroleum industry, is a (semi-)solid composite composed of petroleum hydrocarbons, water, particulate matters and other harmful substances (such as heavy metals), classified as hazardous waste due to the toxicity and ignitability. The annual output of oily sludge in China is up to 5 million tons, including 15%~50% of petroleum hydrocarbons. If oily sludge is treated improperly, it will not only pose a huge threat to the ecosystem, but also cause waste of non-renewable resources. Therefore, the disposal of oily sludge should balance harmless treatment and resource utilization. Based on the composition, characteristics and hazards of oily sludge, this work introduced the separation technologies of oil resources (centrifugation, solvent extraction, pyrolysis) and residual oily residue harmless treatment methods (incineration, solidification stabilization, biological treatment). In general, the integrated treatment technology routine of oily sludge is: 1) reduce the moisture content and increase the oil concentration by pretreatment; 2) recover the petroleum hydrocarbons in the oily sludge by oil separation methods; 3) treat the oil-bearing residue harmlessly finally. Meanwhile, the characteristics of each method and the research progress were discussed, and suggestions for the development of oily sludge treatment technology were aproposed.
2020, 38(8): 217-221.
doi: 10.13205/j.hjgc.202008036
Abstract:
The rice straw was used as the raw material for anaerobic fermentation. Under the wet batch fermentation conditions with medium temperature (37 ℃), the low temperature freezing pretreatment was investigated at different temperatures (-5, -18, -40, -60 ℃) and times (12, 24, 36 h), to discover the effect of time on the gas production performance of rice straw anaerobic fermentation. The experimental results showed that low temperature freezing pretreatment significantly increased the COD content of straw dissolution, and D3 treatment increased by 7.65 times, compared with the control. Low temperature freeze pretreatment significantly reduced the lignin content by 16.36%~59.88%. Under the pretreatment of -5 ℃, -18 ℃, -40 ℃ freezing temperature, the gas production rate and methane content of rice straw anaerobic fermentation increased with the extension of pretreatment time. Among them, gas production rate of D2 treatment and methane content of D3 treatment was the highest, increased by 96.46% and 209.30% compared with the control group.
The rice straw was used as the raw material for anaerobic fermentation. Under the wet batch fermentation conditions with medium temperature (37 ℃), the low temperature freezing pretreatment was investigated at different temperatures (-5, -18, -40, -60 ℃) and times (12, 24, 36 h), to discover the effect of time on the gas production performance of rice straw anaerobic fermentation. The experimental results showed that low temperature freezing pretreatment significantly increased the COD content of straw dissolution, and D3 treatment increased by 7.65 times, compared with the control. Low temperature freeze pretreatment significantly reduced the lignin content by 16.36%~59.88%. Under the pretreatment of -5 ℃, -18 ℃, -40 ℃ freezing temperature, the gas production rate and methane content of rice straw anaerobic fermentation increased with the extension of pretreatment time. Among them, gas production rate of D2 treatment and methane content of D3 treatment was the highest, increased by 96.46% and 209.30% compared with the control group.
2020, 38(8): 222-228,254.
doi: 10.13205/j.hjgc.202008037
Abstract:
Several materials such as typical sulfides, phosphorus-containing, calcium-containing, magnesium-containing, clay minerals were used to immobilize two kinds of slags containing zinc (Zn) and cadmium (Cd), respectively. The effects of different materials on the coexistence of arsenic(As) in slags were also investigated. The immobilization effect was evaluated by H2SO4-HNO3 leaching method. China national standard, GB 18598—2001 was taken as the standard requirement. Finally, the purpose of efficient and safe disposal of waste slags can be achieved. The results of immobilization of No.1 slag showed that: Na2S·9H2O, Na3PO4·12H2O, CaO, MgO, bentonite had obvious immobilization effect on Zn and Cd, but the application of phosphorus-containing materials made As leaching detected. The results of No.2 slag showed that the immobilization effects of Zn, Cd and As were Na2S·9H2O>Na3PO4·12H2O>(NH4)2HPO4, Na3PO4·12H2O and (NH4)2HPO4 were easy to activate As, although they had high immobilization efficiency on Zn; MgO showed better performance than CaO, and the MgO immobilization rates for Zn, Cd, As reached 86.99%, 91.37%, 90.88% respectively at 1% dosage. MgO and Na2S·9H2O were the best immobilizing materials. This study could provide data support for efficient immobilization technology of slags containing Zn, Cd and As in China.
Several materials such as typical sulfides, phosphorus-containing, calcium-containing, magnesium-containing, clay minerals were used to immobilize two kinds of slags containing zinc (Zn) and cadmium (Cd), respectively. The effects of different materials on the coexistence of arsenic(As) in slags were also investigated. The immobilization effect was evaluated by H2SO4-HNO3 leaching method. China national standard, GB 18598—2001 was taken as the standard requirement. Finally, the purpose of efficient and safe disposal of waste slags can be achieved. The results of immobilization of No.1 slag showed that: Na2S·9H2O, Na3PO4·12H2O, CaO, MgO, bentonite had obvious immobilization effect on Zn and Cd, but the application of phosphorus-containing materials made As leaching detected. The results of No.2 slag showed that the immobilization effects of Zn, Cd and As were Na2S·9H2O>Na3PO4·12H2O>(NH4)2HPO4, Na3PO4·12H2O and (NH4)2HPO4 were easy to activate As, although they had high immobilization efficiency on Zn; MgO showed better performance than CaO, and the MgO immobilization rates for Zn, Cd, As reached 86.99%, 91.37%, 90.88% respectively at 1% dosage. MgO and Na2S·9H2O were the best immobilizing materials. This study could provide data support for efficient immobilization technology of slags containing Zn, Cd and As in China.
2020, 38(8): 229-235.
doi: 10.13205/j.hjgc.202008038
Abstract:
In this paper, GIS software and Kriging interpolation method were used to analyze the spatial and temporal distribution of PM2.5 concentration in Hefei city circle. According to historical environment monitoring data, ground meteorological stations and historical meteorological data of Hefei, multiple regression analysis, correlation analysis and other methods were adopted to study the influencing factors of PM2.5 concentration in Hefei. The results showed that: 1) the overall change of PM2.5 concentration in the above cities was in the order of winter > autumn > spring > summer, and PM2.5 concentration in most cities peaked in January, then gradually declined, reached the lowest value in July, and then gradually increased; 2) PM2.5 concentration showed a highly positive correlation with CO, with the correlation coefficient as high as 0.875. The correlation with PM10, SO2 and NO2 was also high. There was a negative correlation with O3. PM2.5 concentration was negatively correlated with air pressure, wind speed, rainfall and visibility, and strongly positively correlated with temperature and relative humidity. Based on PM2.5 concentration monitoring data of Hefei from 2018 to 2019, a composite model was built to predict PM2.5 concentration, and three times exponential smoothing model was compared to determine that simulated annealing+genetic+three times exponential smoothing was the optimal composite model, with the fitting degree reaching 95%. Kappa and MAPE indexes were used to analyze and evaluate the uncertainty of the composite model. Kappa and MAPE indexes were 0.654 and 0.072 respectively, indicating that the model was highly stable. The proper combination of prediction factors and the study of model uncertainty were helpful to improve the model prediction accuracy, so as to provide theoretical basis and method for the monitoring and evaluation of atmospheric environment quality.
In this paper, GIS software and Kriging interpolation method were used to analyze the spatial and temporal distribution of PM2.5 concentration in Hefei city circle. According to historical environment monitoring data, ground meteorological stations and historical meteorological data of Hefei, multiple regression analysis, correlation analysis and other methods were adopted to study the influencing factors of PM2.5 concentration in Hefei. The results showed that: 1) the overall change of PM2.5 concentration in the above cities was in the order of winter > autumn > spring > summer, and PM2.5 concentration in most cities peaked in January, then gradually declined, reached the lowest value in July, and then gradually increased; 2) PM2.5 concentration showed a highly positive correlation with CO, with the correlation coefficient as high as 0.875. The correlation with PM10, SO2 and NO2 was also high. There was a negative correlation with O3. PM2.5 concentration was negatively correlated with air pressure, wind speed, rainfall and visibility, and strongly positively correlated with temperature and relative humidity. Based on PM2.5 concentration monitoring data of Hefei from 2018 to 2019, a composite model was built to predict PM2.5 concentration, and three times exponential smoothing model was compared to determine that simulated annealing+genetic+three times exponential smoothing was the optimal composite model, with the fitting degree reaching 95%. Kappa and MAPE indexes were used to analyze and evaluate the uncertainty of the composite model. Kappa and MAPE indexes were 0.654 and 0.072 respectively, indicating that the model was highly stable. The proper combination of prediction factors and the study of model uncertainty were helpful to improve the model prediction accuracy, so as to provide theoretical basis and method for the monitoring and evaluation of atmospheric environment quality.
2020, 38(8): 236-243,206.
doi: 10.13205/j.hjgc.202008039
Abstract:
In order to promote scientific emission reduction and precise prevention and control of air pollution, PM2.5, PM10, SO2, CO, NO2 and O3 were selected as evaluation factors, and the weight set of pollution factors was established by the entropy weight method. Based on the expanded environmental air quality standard, the membership degree of each evaluation factor was calculated, and the rings of 11 cities in Fenwei Plain in different seasons were determined. The ambient air quality was evaluated by fuzzy comprehensive evaluation, and the air pollution level and seasonal variation characteristics of each city were obtained. The results showed that the air quality of the cities in this area varied greatly with the season. The air quality in spring, summer and autumn was obviously better than that in winter. PM2.5, PM10, SO2 and O3 were the main pollutants. The evaluation results could objectively and comprehensively reflect the air quality in different seasons in this area.
In order to promote scientific emission reduction and precise prevention and control of air pollution, PM2.5, PM10, SO2, CO, NO2 and O3 were selected as evaluation factors, and the weight set of pollution factors was established by the entropy weight method. Based on the expanded environmental air quality standard, the membership degree of each evaluation factor was calculated, and the rings of 11 cities in Fenwei Plain in different seasons were determined. The ambient air quality was evaluated by fuzzy comprehensive evaluation, and the air pollution level and seasonal variation characteristics of each city were obtained. The results showed that the air quality of the cities in this area varied greatly with the season. The air quality in spring, summer and autumn was obviously better than that in winter. PM2.5, PM10, SO2 and O3 were the main pollutants. The evaluation results could objectively and comprehensively reflect the air quality in different seasons in this area.
2020, 38(8): 244-248.
doi: 10.13205/j.hjgc.202008040
Abstract:
To apply an improved integrated index method to evaluate the quality of three types of drinking water, the selected 26 indicators were classified into five categories according to various hygienic significances. And an appropriate weight was given to each category. Nemerow, minimum operator and five-color classification method were combined to evaluate the overall quality of the three types of drinking water from April to August in 2017. Except tap water in July and August, the quality index was at Level 2 (>0.5, blue), while other water all reached Level 1 (green). The organic pollution indicator was the most important impact of integrated index in different types of drinking water. Furthermore, the quality of two different water purifiers were better than the tap water, but some indicators require special attention.
To apply an improved integrated index method to evaluate the quality of three types of drinking water, the selected 26 indicators were classified into five categories according to various hygienic significances. And an appropriate weight was given to each category. Nemerow, minimum operator and five-color classification method were combined to evaluate the overall quality of the three types of drinking water from April to August in 2017. Except tap water in July and August, the quality index was at Level 2 (>0.5, blue), while other water all reached Level 1 (green). The organic pollution indicator was the most important impact of integrated index in different types of drinking water. Furthermore, the quality of two different water purifiers were better than the tap water, but some indicators require special attention.
2020, 38(8): 249-254.
doi: 10.13205/j.hjgc.202008041
Abstract:
Xiangjiang River is a typical urban stream flowing through the main urban area of Zunyi. To evaluate the pollution characteristics and ecological risk of mercury of Zunyi Xiangjiang River, the surface sediments system were collected and analyzed. The results showed that the mercury content of surface sediments was ranged in 0.131~3.132 ng/g and the mercury content in downstream of both river water and sediments was much higher than upstream, and was positively correlated with the distance passed though urban areas. The methyl mercury concentration of surface sediments was ranged in 2.1~31.4 ng/g and accounted for 1.11%~1.87% of the total mercury. Furthermore, the results of BCR three-step sequential extraction procedure showed that the mercury in the sediment was mainly in the form of residue. The risk assessment indicated that the Xiangjiang River was mildly polluted while it had considerable potential ecological risk.
Xiangjiang River is a typical urban stream flowing through the main urban area of Zunyi. To evaluate the pollution characteristics and ecological risk of mercury of Zunyi Xiangjiang River, the surface sediments system were collected and analyzed. The results showed that the mercury content of surface sediments was ranged in 0.131~3.132 ng/g and the mercury content in downstream of both river water and sediments was much higher than upstream, and was positively correlated with the distance passed though urban areas. The methyl mercury concentration of surface sediments was ranged in 2.1~31.4 ng/g and accounted for 1.11%~1.87% of the total mercury. Furthermore, the results of BCR three-step sequential extraction procedure showed that the mercury in the sediment was mainly in the form of residue. The risk assessment indicated that the Xiangjiang River was mildly polluted while it had considerable potential ecological risk.
