Login
Register
E-alert
2021 Vol. 39, No. 8
Display Method:
2021, 39(8): 1-6.
doi: 10.13205/j.hjgc.202108001
Abstract:
Hydrocyclone separators have advantages of high separation efficiency, simplicity, reliability and low cost, which has been widely used in various separation scenarios, especially in wastewater treatment in recent years. This article reviewed the operating parameters (feed flow rate, feed concentration, feed pressure), structural design parameters (overflow pipe insertion depth, underflow pipe diameter, reflux angle) and configuration types (W type, parabolic type, completely cylindrical type) on the hydrocyclones separation performance. Optimizing the operating parameters could enhance the separation efficiency; the flow field generated when the ratio of overflow pipe insertion depth to cylindrical cross section diameter (L0/D) equaled 1.0 was conducive to separation; the underflow pipe diameter had an optimal range; combining with water source heat pump, the optimal suction angle was 90°. The recent progress of hydrocyclone research and application included promoting microbial aggregates (including increasing sludge hydrolysis rate and improving sedimentation performance), separating specific particulate microorganisms (including anaerobic ammonia oxidizing bacteria granular sludge) and removing or recovering substances with specific density (including suspended organic matter, mud sand, metal particles), which opened up new perspectives for hydrocyclones future application in wastewater treatment.
Hydrocyclone separators have advantages of high separation efficiency, simplicity, reliability and low cost, which has been widely used in various separation scenarios, especially in wastewater treatment in recent years. This article reviewed the operating parameters (feed flow rate, feed concentration, feed pressure), structural design parameters (overflow pipe insertion depth, underflow pipe diameter, reflux angle) and configuration types (W type, parabolic type, completely cylindrical type) on the hydrocyclones separation performance. Optimizing the operating parameters could enhance the separation efficiency; the flow field generated when the ratio of overflow pipe insertion depth to cylindrical cross section diameter (L0/D) equaled 1.0 was conducive to separation; the underflow pipe diameter had an optimal range; combining with water source heat pump, the optimal suction angle was 90°. The recent progress of hydrocyclone research and application included promoting microbial aggregates (including increasing sludge hydrolysis rate and improving sedimentation performance), separating specific particulate microorganisms (including anaerobic ammonia oxidizing bacteria granular sludge) and removing or recovering substances with specific density (including suspended organic matter, mud sand, metal particles), which opened up new perspectives for hydrocyclones future application in wastewater treatment.
2021, 39(8): 7-14.
doi: 10.13205/j.hjgc.202108002
Abstract:
Plants play an important part in water treatment function of constructed wetlands, in order to in-depth study the mechanism of salt-tolerant plants in purifying salt water and the role of synergistic filler, Canna indica L., Spartina alterniflora Loisel, Scirpus mariqueter, were chosen as the research objects, cooperating with compound fillers, to study the difference of pollutant removal effect in different, with different carbon to nitrogen ratios and salinity conditions. Simultaneously, we analyzed the enzyme activity in the plants in the experimental device, the diversity of microorganisms attached to the rhizosphere and the surface of the filler, and the microbial community structure. The results showed that: 1) constructed wetland could effectively treat coastal saline water. When HRT was 4 days, C/N was 3∶1 and salinity was 1‰, the removal effect of total nitrogen, total phosphorus and COD all reached their peaks; 2)the three salt-tolerant plants all showed certain salt-tolerance, among them, the purification effect of Spartina alterniflora Loisel was the best; 3)the removal rate of total nitrogen, total phosphorus and COD in the Spartina alterniflora Loisel device with new slag material was as high as 95.56%, 95.46% and 63.61%, respectively. At the same time, this device had rich microbial diversity. The device with new slag material optimized the ratio of microorganisms in an orderly manner, promote the synergistic purification of water by Spartina alterniflora and wetland functional microorganisms, which was conducive to take advantage of each bacterial species to prevent the malicious reproduction of the dominant bacterial species. The content of POD, CAT and soluble sugar in the Spartina alterniflora Loisel with the new slag material was higher than that of the other plants, and the content of propylene dione was the lowest, indicating that the plant suffered less harm from adversity and had strong anti-interference ability. This provided scientific basis and technical support for wetland plants to treat coastal or salt-containing sewage.
Plants play an important part in water treatment function of constructed wetlands, in order to in-depth study the mechanism of salt-tolerant plants in purifying salt water and the role of synergistic filler, Canna indica L., Spartina alterniflora Loisel, Scirpus mariqueter, were chosen as the research objects, cooperating with compound fillers, to study the difference of pollutant removal effect in different, with different carbon to nitrogen ratios and salinity conditions. Simultaneously, we analyzed the enzyme activity in the plants in the experimental device, the diversity of microorganisms attached to the rhizosphere and the surface of the filler, and the microbial community structure. The results showed that: 1) constructed wetland could effectively treat coastal saline water. When HRT was 4 days, C/N was 3∶1 and salinity was 1‰, the removal effect of total nitrogen, total phosphorus and COD all reached their peaks; 2)the three salt-tolerant plants all showed certain salt-tolerance, among them, the purification effect of Spartina alterniflora Loisel was the best; 3)the removal rate of total nitrogen, total phosphorus and COD in the Spartina alterniflora Loisel device with new slag material was as high as 95.56%, 95.46% and 63.61%, respectively. At the same time, this device had rich microbial diversity. The device with new slag material optimized the ratio of microorganisms in an orderly manner, promote the synergistic purification of water by Spartina alterniflora and wetland functional microorganisms, which was conducive to take advantage of each bacterial species to prevent the malicious reproduction of the dominant bacterial species. The content of POD, CAT and soluble sugar in the Spartina alterniflora Loisel with the new slag material was higher than that of the other plants, and the content of propylene dione was the lowest, indicating that the plant suffered less harm from adversity and had strong anti-interference ability. This provided scientific basis and technical support for wetland plants to treat coastal or salt-containing sewage.
2021, 39(8): 15-24,33.
doi: 10.13205/j.hjgc.202108003
Abstract:
A CANON-MBBR system was used to treat the actual sludge-digestion wastewater, and stable operation control strategy of the system was investigated. The results showed that during the stable period, the ammonia nitrogen concentration in the effluent of the system was stable below 25 mg/L and the removal rate was above 96%; the TIN concentration in the effluent was below 70 mg/L and the removal rate was above 87%. The system maintained pure MBBR without the sludge backflow and supplemental injection of strains, and achieved a stable autotrophic denitrification process. During the operation, the impact of water quantity, DO and temperature on the stability of the system were investigated. The results showed that the system still maintained high nitrogen removal performance under the conditions of 1.33 times of water impact, high DO range of 2~4 mg/L and low temperature of 24 ℃. The ammonia-oxidizing bacteria (AOB) and anaerobic ammonia-oxidizing bacteria (AnAOB) were Nitrosomonas and Candidatus Kuenenia, respectively, and their average relative abundance were 6.5% and 30.2%, respectively. The relative abundance of nitrite oxidizing bacteria (NOB) was always lower than 0.1%, which realized NOB suppression. AOB and AnAOB were enriched efficiently by suspended carrier biofilm, but the low AOB abundance of the system limited the further improvement of the system’s nitrogen removal performance.
A CANON-MBBR system was used to treat the actual sludge-digestion wastewater, and stable operation control strategy of the system was investigated. The results showed that during the stable period, the ammonia nitrogen concentration in the effluent of the system was stable below 25 mg/L and the removal rate was above 96%; the TIN concentration in the effluent was below 70 mg/L and the removal rate was above 87%. The system maintained pure MBBR without the sludge backflow and supplemental injection of strains, and achieved a stable autotrophic denitrification process. During the operation, the impact of water quantity, DO and temperature on the stability of the system were investigated. The results showed that the system still maintained high nitrogen removal performance under the conditions of 1.33 times of water impact, high DO range of 2~4 mg/L and low temperature of 24 ℃. The ammonia-oxidizing bacteria (AOB) and anaerobic ammonia-oxidizing bacteria (AnAOB) were Nitrosomonas and Candidatus Kuenenia, respectively, and their average relative abundance were 6.5% and 30.2%, respectively. The relative abundance of nitrite oxidizing bacteria (NOB) was always lower than 0.1%, which realized NOB suppression. AOB and AnAOB were enriched efficiently by suspended carrier biofilm, but the low AOB abundance of the system limited the further improvement of the system’s nitrogen removal performance.
2021, 39(8): 25-33.
doi: 10.13205/j.hjgc.202108004
Abstract:
The coupling system of constructed wetland (CW) and microbial fuel cell (MFC) is a new type of bioelectrochemical system. The system has multi-function of wastewater treatment and biological power generation. This article combined the recent studies on the power generation and pollutant degradation performance of the constructed wetland-microbial fuel cell coupling system (CW-MFC), and summarized the latest research progress of the CW-MFC system, mainly focused on the system structure (wetland plants, microorganisms, electrode materials, matrix materials) and the factors affecting system operation (hydraulic retention time, dissolved oxygen, organic load and wastewater composition, redox potential). Finally, the challenges in CW-MFC and the future development direction were summarized, and the research potential of the system was also prospected.
The coupling system of constructed wetland (CW) and microbial fuel cell (MFC) is a new type of bioelectrochemical system. The system has multi-function of wastewater treatment and biological power generation. This article combined the recent studies on the power generation and pollutant degradation performance of the constructed wetland-microbial fuel cell coupling system (CW-MFC), and summarized the latest research progress of the CW-MFC system, mainly focused on the system structure (wetland plants, microorganisms, electrode materials, matrix materials) and the factors affecting system operation (hydraulic retention time, dissolved oxygen, organic load and wastewater composition, redox potential). Finally, the challenges in CW-MFC and the future development direction were summarized, and the research potential of the system was also prospected.
2021, 39(8): 34-44.
doi: 10.13205/j.hjgc.202108005
Abstract:
Phthalates (PAEs), as common environmental hormones in wastewater, are listed as "priority control pollutants" by many countries due to the great threat to human beings and organisms in water. A series of polyoxometalate-based materials (AgxH5-xPMo10V2O40, x =1~5) were designed and synthesized, and the catalytic wet peroxide oxidation (CWPO) was employed to realize the efficient oxidation of diethyl phthalate (DEP) with degradation efficiency of 91.0% at 20 min. Furthermore, the degradation products of DEP were low toxic of lactic acid, CO2 and H2O, while the removal efficiency of total organic carbon and chemical oxygen demand achieved 70.2% and 81.1%, respectively. Overall, the catalyst exhibited high activity, stability and recyclability, which showed great tolerance for different phthalates and excellent removals for trace DEP.
Phthalates (PAEs), as common environmental hormones in wastewater, are listed as "priority control pollutants" by many countries due to the great threat to human beings and organisms in water. A series of polyoxometalate-based materials (AgxH5-xPMo10V2O40, x =1~5) were designed and synthesized, and the catalytic wet peroxide oxidation (CWPO) was employed to realize the efficient oxidation of diethyl phthalate (DEP) with degradation efficiency of 91.0% at 20 min. Furthermore, the degradation products of DEP were low toxic of lactic acid, CO2 and H2O, while the removal efficiency of total organic carbon and chemical oxygen demand achieved 70.2% and 81.1%, respectively. Overall, the catalyst exhibited high activity, stability and recyclability, which showed great tolerance for different phthalates and excellent removals for trace DEP.
2021, 39(8): 45-54,61.
doi: 10.13205/j.hjgc.202108006
Abstract:
Partial nitrification-anammox(PN/A)process is considered to be a viable alternative to traditional nitrification-denitrification technology and become the mainstream nitrogen removal technology to achieve energy self-sufficiency in wastewater treatment plants(WTTPs), because of its low consumption and high efficiency. Based on the existing bottlenecks and challenges of mainstream PN/A process, such as partial nitrification instability and difficulties of enriching functional bacteria, the current application status of the PN/A reactor was summarized, the retention and enrichment methods of ammonia oxidizing bacteria (AOB) and anaerobic ammonia oxidizing bacteria (AnAOB) were reviewed in this article. Strategies for effective nitrite oxidizing bacteria (NOB) inhibition were also analyzed, while future development suggestions were put forward for the current problems, to provide scientific reference for the mainstream PN/A process to realize engineering and scale-up.
Partial nitrification-anammox(PN/A)process is considered to be a viable alternative to traditional nitrification-denitrification technology and become the mainstream nitrogen removal technology to achieve energy self-sufficiency in wastewater treatment plants(WTTPs), because of its low consumption and high efficiency. Based on the existing bottlenecks and challenges of mainstream PN/A process, such as partial nitrification instability and difficulties of enriching functional bacteria, the current application status of the PN/A reactor was summarized, the retention and enrichment methods of ammonia oxidizing bacteria (AOB) and anaerobic ammonia oxidizing bacteria (AnAOB) were reviewed in this article. Strategies for effective nitrite oxidizing bacteria (NOB) inhibition were also analyzed, while future development suggestions were put forward for the current problems, to provide scientific reference for the mainstream PN/A process to realize engineering and scale-up.
2021, 39(8): 55-61.
doi: 10.13205/j.hjgc.202108007
Abstract:
The treatment of pig raising wastewater by traditional anaerobic fermentation methods has some limitations for application such as low efficiency, long cycle length, and strict environmental requirements, which cannot treat pig raising wastewater with high efficiency. In this paper, we filtered the suspended solids from pig rearing wastewater by using corn straw, based on an autonomous designed integrated resource-based utilization technology, comparatively studied the properties before and after wastewater filtration, and analyzed the bacterial and archaeal community composition and change characteristics of filtered pig rearing wastewater during anaerobic fermentation by using high-throughput sequencing. The results of this study showed that anaerobic fermentation process was condutcted by multiple microbial flora, and that the predominant bacterial taxa in filtered pig wastewater at different hydraulic residence times were Firmicutes, Actinobacteria, Bacteroidetes, and the presence of spirochaetes was detected in all three samples except inoculum. In addition, the main archaeal group in wastewater was the phylum Guanggu, and the main acting bacteria were methanogens. Hydraulic retention time variation had a significant impact on archaeal community change, resulting in differential methanogenesis. The changes in microbial communities and wastewater indicators indicated that the comprehensive and resource-based technology of breeding waste reduced the treatment cost, and had reference significance for recycling wastewater resources from pig cultivation.
The treatment of pig raising wastewater by traditional anaerobic fermentation methods has some limitations for application such as low efficiency, long cycle length, and strict environmental requirements, which cannot treat pig raising wastewater with high efficiency. In this paper, we filtered the suspended solids from pig rearing wastewater by using corn straw, based on an autonomous designed integrated resource-based utilization technology, comparatively studied the properties before and after wastewater filtration, and analyzed the bacterial and archaeal community composition and change characteristics of filtered pig rearing wastewater during anaerobic fermentation by using high-throughput sequencing. The results of this study showed that anaerobic fermentation process was condutcted by multiple microbial flora, and that the predominant bacterial taxa in filtered pig wastewater at different hydraulic residence times were Firmicutes, Actinobacteria, Bacteroidetes, and the presence of spirochaetes was detected in all three samples except inoculum. In addition, the main archaeal group in wastewater was the phylum Guanggu, and the main acting bacteria were methanogens. Hydraulic retention time variation had a significant impact on archaeal community change, resulting in differential methanogenesis. The changes in microbial communities and wastewater indicators indicated that the comprehensive and resource-based technology of breeding waste reduced the treatment cost, and had reference significance for recycling wastewater resources from pig cultivation.
2021, 39(8): 62-68.
doi: 10.13205/j.hjgc.202108008
Abstract:
In order to study the migration, transformation and REDOX zoning of tri-nitrogen in subsurface flow zone driven by riverside mining, soil samples and water samples were collected from subsurface flow zone in different periods of riverside collection to analyze the transformation process and characteristics of tri-nitrogen, and the migration and transformation law and mechanism were determined by combining dissolved oxygen, redox potential, nitrate and nitrite content and dominant bacteria. The results showed that in the process of infiltration, the river water firstly entered the oxidation zone in -6~1.5 m offshore, O2 reacted with organic matters to release CO2, then went to the oxidation-reduction transition zone of weak oxidation environment in 1.5~17 m offshore, nitration and denitrification reactions occurred under the action of nitrifying bacteria and denitrifying bacteria, and finally entered into the reduction zone of anoxic environment in 17~350 m offshore, denitrification happened under anoxic condition. The dominant bacteria had some connection and response to Redox Zoning. Low water level in dry season was conducive to reduce DO, NH3-N and NO3--N more quickly, so the REDOX distance was shorter in dry season and longer in wet season. Driven by riverside collection, hydrodynamic conditions changed with different periods, and there were differences in various aspects in the process of river recharge to groundwater, which affected the migration and transformation of nitrogen into underground media.
In order to study the migration, transformation and REDOX zoning of tri-nitrogen in subsurface flow zone driven by riverside mining, soil samples and water samples were collected from subsurface flow zone in different periods of riverside collection to analyze the transformation process and characteristics of tri-nitrogen, and the migration and transformation law and mechanism were determined by combining dissolved oxygen, redox potential, nitrate and nitrite content and dominant bacteria. The results showed that in the process of infiltration, the river water firstly entered the oxidation zone in -6~1.5 m offshore, O2 reacted with organic matters to release CO2, then went to the oxidation-reduction transition zone of weak oxidation environment in 1.5~17 m offshore, nitration and denitrification reactions occurred under the action of nitrifying bacteria and denitrifying bacteria, and finally entered into the reduction zone of anoxic environment in 17~350 m offshore, denitrification happened under anoxic condition. The dominant bacteria had some connection and response to Redox Zoning. Low water level in dry season was conducive to reduce DO, NH3-N and NO3--N more quickly, so the REDOX distance was shorter in dry season and longer in wet season. Driven by riverside collection, hydrodynamic conditions changed with different periods, and there were differences in various aspects in the process of river recharge to groundwater, which affected the migration and transformation of nitrogen into underground media.
2021, 39(8): 69-76.
doi: 10.13205/j.hjgc.202108009
Abstract:
Qinzhou Gulf was selected as the research area because of frequently human activities. Seven heavy metals in surface sediments were studied by various methods. The results showed that the contents of As and Hg were higher than those in other similar areas, the contents of Pb and Cr were equal, and the contents of Cr, Cu and Zn were lower. In recent years, the content heavy metal contents increased, and the high value points were all close to some industrial sewage emission and human activity areas. The evaluation results of random accumulation model showed that Cd was in no pollution to medium pollution level, and 34% of them had probability to deteriorate to medium pollution level; other heavy metals were in no pollution level, and 48% of As and 24% of Hg had the probability of deterioration. The order of potential ecological risk was Cd>Hg>As»Pb>Cu>Zn≈Cr; speciation analysis showed that Hg mainly existed in the form of stable residue, suggesting that the migration between sediment and seawater was weak and the availability of Hg was low; the results of principal component analysis showed that Cd mainly came from port shipping and dredging activities, and other heavy metals mainly came from industry (sugar, coal, petrochemical, etc.) and land-based municipal sewage. The heavy metal content in Qinzhou Bay was mainly affected by industry and human activities.
Qinzhou Gulf was selected as the research area because of frequently human activities. Seven heavy metals in surface sediments were studied by various methods. The results showed that the contents of As and Hg were higher than those in other similar areas, the contents of Pb and Cr were equal, and the contents of Cr, Cu and Zn were lower. In recent years, the content heavy metal contents increased, and the high value points were all close to some industrial sewage emission and human activity areas. The evaluation results of random accumulation model showed that Cd was in no pollution to medium pollution level, and 34% of them had probability to deteriorate to medium pollution level; other heavy metals were in no pollution level, and 48% of As and 24% of Hg had the probability of deterioration. The order of potential ecological risk was Cd>Hg>As»Pb>Cu>Zn≈Cr; speciation analysis showed that Hg mainly existed in the form of stable residue, suggesting that the migration between sediment and seawater was weak and the availability of Hg was low; the results of principal component analysis showed that Cd mainly came from port shipping and dredging activities, and other heavy metals mainly came from industry (sugar, coal, petrochemical, etc.) and land-based municipal sewage. The heavy metal content in Qinzhou Bay was mainly affected by industry and human activities.
2021, 39(8): 77-87.
doi: 10.13205/j.hjgc.202108010
Abstract:
In recent years, the pollution status and removal technology of emerging organic pollutants received widespread attention. As the emerging organic pollutants cannot be effectively removed by traditional sewage treatment plants, they will enter the ecological environment together with the sewage treatment plant effluent, sludge, etc., and cause harm. Therefore, in order to effectively remove such pollutants, new treatment technologies gradually become a research hotspot in recent years. By summarizing the treatment status and harms of emerging organic pollutants in sewage treatment plants, new treatment technologies were reviewed including activated persulfate, intimate coupling of photocatalysis and biodegradation technology, ozone microbubble method, metal-organic framework materials, immobilized microorganisms, immobilized laccase degradation technology, etc. And the advantages and disadvantages of various technologies were analyzed. The results showed that the current new treatment technologies for emerging organic pollutants were mainly in the laboratory research stage, and most of them were single technology studies, Some treatment processes even produced toxic and harmful products. It was suggested that mathematical model should be established to make it more convenient and economical to predict the degradation ability of the treatment process, assess the toxicity and environmental risk of pollutants, further screen the high-efficiency strains, and develope safe and reliable new treatment materials. Emerging pollutants were then eliminated from the root, through cleaner production.
In recent years, the pollution status and removal technology of emerging organic pollutants received widespread attention. As the emerging organic pollutants cannot be effectively removed by traditional sewage treatment plants, they will enter the ecological environment together with the sewage treatment plant effluent, sludge, etc., and cause harm. Therefore, in order to effectively remove such pollutants, new treatment technologies gradually become a research hotspot in recent years. By summarizing the treatment status and harms of emerging organic pollutants in sewage treatment plants, new treatment technologies were reviewed including activated persulfate, intimate coupling of photocatalysis and biodegradation technology, ozone microbubble method, metal-organic framework materials, immobilized microorganisms, immobilized laccase degradation technology, etc. And the advantages and disadvantages of various technologies were analyzed. The results showed that the current new treatment technologies for emerging organic pollutants were mainly in the laboratory research stage, and most of them were single technology studies, Some treatment processes even produced toxic and harmful products. It was suggested that mathematical model should be established to make it more convenient and economical to predict the degradation ability of the treatment process, assess the toxicity and environmental risk of pollutants, further screen the high-efficiency strains, and develope safe and reliable new treatment materials. Emerging pollutants were then eliminated from the root, through cleaner production.
EXTRACTION OF HUMIC ACID AND BLACK CARBON AND THEIR ADSORPTION BEHAVIORS FOR PHENANTHRENE AND PYRENE
2021, 39(8): 88-92,107.
doi: 10.13205/j.hjgc.202108011
Abstract:
In this study, humic acid and black carbon were firstly extracted from river sediments, then characterized and analyzed by element analyzer, total organic carbon meter, scanning electron microscope and Zeta potential meter. The distribution behaviors of phenanthrene and pyrene, representative substances of polycyclic aromatic hydrocarbons (PAHs) on humic acid and black carbon were studied, and their distribution coefficients were determined, as well as the influence of Ca2+ concentration on the adsorption of phenanthrene and pyrene were investigated. The results showed that the main elemental composition of humic acid and black carbon extracted from river sediments were carbon and oxygen, both of which contained relatively rich aromatic hydrocarbon components; aquatic plants were the main contributors of the source of humic acid and black carbon; humic acid had a foamed floc structure, and black carbon had a microporous structure; the negative charge on the surface of black carbon particles was relatively less than that of humic acid, so the repulsive force between the black carbon and pollutants was weaker. The above characterization results correspondingly provided theoretical basis for the adsorption capacity of black carbon higher than that of humic acid. The logarithmic value (lg Kd) of the partition coefficient of phenanthrene and pyrene on humic acid were 3.55 and 4.55, respectively, and that on black carbon were 4.57 and 5.35, respectively, which showed that the absorption amount of pyrene on unit mass of humic acid or black carbon was higher than that of phenanthrene; the adsorption amount of phenanthrene and pyrene on the humic acid and black carbon also showed a trend of increasing and then decreasing with the increase of Ca2+ concentration.
In this study, humic acid and black carbon were firstly extracted from river sediments, then characterized and analyzed by element analyzer, total organic carbon meter, scanning electron microscope and Zeta potential meter. The distribution behaviors of phenanthrene and pyrene, representative substances of polycyclic aromatic hydrocarbons (PAHs) on humic acid and black carbon were studied, and their distribution coefficients were determined, as well as the influence of Ca2+ concentration on the adsorption of phenanthrene and pyrene were investigated. The results showed that the main elemental composition of humic acid and black carbon extracted from river sediments were carbon and oxygen, both of which contained relatively rich aromatic hydrocarbon components; aquatic plants were the main contributors of the source of humic acid and black carbon; humic acid had a foamed floc structure, and black carbon had a microporous structure; the negative charge on the surface of black carbon particles was relatively less than that of humic acid, so the repulsive force between the black carbon and pollutants was weaker. The above characterization results correspondingly provided theoretical basis for the adsorption capacity of black carbon higher than that of humic acid. The logarithmic value (lg Kd) of the partition coefficient of phenanthrene and pyrene on humic acid were 3.55 and 4.55, respectively, and that on black carbon were 4.57 and 5.35, respectively, which showed that the absorption amount of pyrene on unit mass of humic acid or black carbon was higher than that of phenanthrene; the adsorption amount of phenanthrene and pyrene on the humic acid and black carbon also showed a trend of increasing and then decreasing with the increase of Ca2+ concentration.
2021, 39(8): 93-98.
doi: 10.13205/j.hjgc.202108012
Abstract:
In view of the current situation of phosphorus pollution such as excessive phosphorus content in effluent of the secondary sedimentation tank of a sewage plant, a new material Fe3O4@CNF@Zn-BTC was synthesized for specific adsorption of phosphorus. It was made of magnetic nano Fe3O4 particles, carboxylated cellulose nanocrystals and metal organic framework Zn-BTC under general laboratory conditions. The loading of CNF material and MOFs material improved the crystallinity of the composite material, and then improved the rigidity and stability of the composite material, and produced the related bonds between TOCNF surface -COO- and Fe and MOFs, which improved the porosity of the composite material and the rigidity of the material at the same time, and overcome the shortcomings of rigidity and stability of MOFs material to a great extent. Fe3O4@CNF@Zn-BTC was characterized by SEM, FTIR, XRD, XPS and BET, and its removal effect on trace phosphorus in water was discussed under normal temperature and pressure. The results showed that the phosphorus content could be reduced to 0.3~0.5 mg/L by adding a small amount of Fe3O4@CNF@Zn-BTC at normal temperature and pressure for 60 minutes, which met the first class A standard specified in GB 18918—2002, and then the average removal rate was as high as 95%. Compared with other conventional phosphorus removal materials such as activated carbon, Fe3O4@CNF@Zn-BTC material had higher phosphorus removal efficiency, simpler recovery, stronger reproducibility, lower cost and easier synthesis process. Therefore, Fe3O4@CNF@Zn-BTC showed great prospects in improving the water quality of phosphorus polluted environment.
In view of the current situation of phosphorus pollution such as excessive phosphorus content in effluent of the secondary sedimentation tank of a sewage plant, a new material Fe3O4@CNF@Zn-BTC was synthesized for specific adsorption of phosphorus. It was made of magnetic nano Fe3O4 particles, carboxylated cellulose nanocrystals and metal organic framework Zn-BTC under general laboratory conditions. The loading of CNF material and MOFs material improved the crystallinity of the composite material, and then improved the rigidity and stability of the composite material, and produced the related bonds between TOCNF surface -COO- and Fe and MOFs, which improved the porosity of the composite material and the rigidity of the material at the same time, and overcome the shortcomings of rigidity and stability of MOFs material to a great extent. Fe3O4@CNF@Zn-BTC was characterized by SEM, FTIR, XRD, XPS and BET, and its removal effect on trace phosphorus in water was discussed under normal temperature and pressure. The results showed that the phosphorus content could be reduced to 0.3~0.5 mg/L by adding a small amount of Fe3O4@CNF@Zn-BTC at normal temperature and pressure for 60 minutes, which met the first class A standard specified in GB 18918—2002, and then the average removal rate was as high as 95%. Compared with other conventional phosphorus removal materials such as activated carbon, Fe3O4@CNF@Zn-BTC material had higher phosphorus removal efficiency, simpler recovery, stronger reproducibility, lower cost and easier synthesis process. Therefore, Fe3O4@CNF@Zn-BTC showed great prospects in improving the water quality of phosphorus polluted environment.
2021, 39(8): 99-107.
doi: 10.13205/j.hjgc.202108013
Abstract:
Groundwater is an important water resource for water supply, and the hydrochemistry is one of the key factors determining its availability. In this study, the southern near-suburb plain of Beijing was taken as an example, multiple approaches including hydrogeochemical diagrams, multiple statistics analysis and spatial interpolation model were performed, to reveal groundwater chemistry and its genesis in arid and semiarid regions undergone rapid urbanization and densely agricultural practices. The results demonstrated that groundwater was generally slightly alkaline fresh water in the study area. The hydrochemical type of groundwater were dominantly HCO3-Ca and Cl-Mg·Ca type, along with a few of HCO3-Na·Ca type. Elevation of NO3- concentrations were observed in both shallow and deep aquifers. The hydrogeochemical faces evolution of shallow and deep groundwater was significantly related to the elevated NO3- concentrations. The dominant anions evolved gradually from HCO3- to SO42- and Cl- with the increase of NO3- concentration. Hydrogeochemical components of shallow and deep groundwater were controlled by both natural and anthropogenic factors. The spatial distribution of dominant controlling factors of groundwater chemistry was governed by the aquifer structures. The hydrochemical compositions of groundwater in the northwestern urban areas with single aquifer structure were dominantly controlled by anthropogenic factors, while that in the southeastern agricultural areas with multiple aquifer structure were mainly governed by natural factors. The natural factors controlling groundwater chemistry included rock weathering, minerals dissolution and ions exchange. Ground surface pollutants input was the main anthropogenic factor controlling groundwater chemistry. While the reclaimed water used for agricultural irrigation was found to have little impact on groundwater chemical evolution.
Groundwater is an important water resource for water supply, and the hydrochemistry is one of the key factors determining its availability. In this study, the southern near-suburb plain of Beijing was taken as an example, multiple approaches including hydrogeochemical diagrams, multiple statistics analysis and spatial interpolation model were performed, to reveal groundwater chemistry and its genesis in arid and semiarid regions undergone rapid urbanization and densely agricultural practices. The results demonstrated that groundwater was generally slightly alkaline fresh water in the study area. The hydrochemical type of groundwater were dominantly HCO3-Ca and Cl-Mg·Ca type, along with a few of HCO3-Na·Ca type. Elevation of NO3- concentrations were observed in both shallow and deep aquifers. The hydrogeochemical faces evolution of shallow and deep groundwater was significantly related to the elevated NO3- concentrations. The dominant anions evolved gradually from HCO3- to SO42- and Cl- with the increase of NO3- concentration. Hydrogeochemical components of shallow and deep groundwater were controlled by both natural and anthropogenic factors. The spatial distribution of dominant controlling factors of groundwater chemistry was governed by the aquifer structures. The hydrochemical compositions of groundwater in the northwestern urban areas with single aquifer structure were dominantly controlled by anthropogenic factors, while that in the southeastern agricultural areas with multiple aquifer structure were mainly governed by natural factors. The natural factors controlling groundwater chemistry included rock weathering, minerals dissolution and ions exchange. Ground surface pollutants input was the main anthropogenic factor controlling groundwater chemistry. While the reclaimed water used for agricultural irrigation was found to have little impact on groundwater chemical evolution.
2021, 39(8): 108-112,233.
doi: 10.13205/j.hjgc.202108014
Abstract:
Pulsed electric field is mainly used in food and medical sterilization, and its widely recognized sterilization mechanism is electroporation theory. Based on that, the pulsed electric field at low voltage and frequency can not only change the permeability of cells, but also ensure that the cells can not be inactivated. In order to explore the influence of pulsed electric field on the denitrification effect of ANAMMOX, different types of electric fields were applied in the constructed reactor respectively. The concentration of influent and effluent NH4+-N and NO2--N and the microbial cell structure were taken as the detection indexes to investigate the denitrification effect under various conditions. The results showed that the pulsed electric field group could effectively maintain the stability of the ANAMMOX reaction, and the TN removal rate reached more than 80%, which was 60% and 20% higher than the TN removal rate in the DC electric field group and the blank group respectively. At the same time, the microorganism structure of pulsed electric field group was more complete than that of the DC electric field group and blank group. The results showed that the pulsed electric field could effectively promote the denitrification effect of ANAMMOX and maintain the running stability of the reaction system.
Pulsed electric field is mainly used in food and medical sterilization, and its widely recognized sterilization mechanism is electroporation theory. Based on that, the pulsed electric field at low voltage and frequency can not only change the permeability of cells, but also ensure that the cells can not be inactivated. In order to explore the influence of pulsed electric field on the denitrification effect of ANAMMOX, different types of electric fields were applied in the constructed reactor respectively. The concentration of influent and effluent NH4+-N and NO2--N and the microbial cell structure were taken as the detection indexes to investigate the denitrification effect under various conditions. The results showed that the pulsed electric field group could effectively maintain the stability of the ANAMMOX reaction, and the TN removal rate reached more than 80%, which was 60% and 20% higher than the TN removal rate in the DC electric field group and the blank group respectively. At the same time, the microorganism structure of pulsed electric field group was more complete than that of the DC electric field group and blank group. The results showed that the pulsed electric field could effectively promote the denitrification effect of ANAMMOX and maintain the running stability of the reaction system.
2021, 39(8): 113-118.
doi: 10.13205/j.hjgc.202108015
Abstract:
In this paper, the pulse-jet cleaning for filter cartridge dust collector was taken as the research object to investigate the influence of the peeling off of the dust cake on the pulse-jet cleaning performance. The numerical model of pulse-jet cleaning was built using CFD software and the cleaning flow field was simulated and analyzed. The results showed that the pulsed-jet pressure formed in the lower part of the filter cartridge was significantly higher than that in the top part. Compared with the fixed dust cake condition, the pulse-jet intensity was lower, the uniformity was worse and the air flow rate penetrating the filter was larger under the dust cake peeling off condition. With the increase of initial total filtration resistance ΔPt (less than 1000 Pa), the pulse-jet intensity and uniformity increased, and the air flow rate penetrating the filter cartridge decreased. These parameters went stable when ΔPt was more than 1000 Pa. These results provided theoretical references for the research and design of the pulse-jet cleaning dust collectors.
In this paper, the pulse-jet cleaning for filter cartridge dust collector was taken as the research object to investigate the influence of the peeling off of the dust cake on the pulse-jet cleaning performance. The numerical model of pulse-jet cleaning was built using CFD software and the cleaning flow field was simulated and analyzed. The results showed that the pulsed-jet pressure formed in the lower part of the filter cartridge was significantly higher than that in the top part. Compared with the fixed dust cake condition, the pulse-jet intensity was lower, the uniformity was worse and the air flow rate penetrating the filter was larger under the dust cake peeling off condition. With the increase of initial total filtration resistance ΔPt (less than 1000 Pa), the pulse-jet intensity and uniformity increased, and the air flow rate penetrating the filter cartridge decreased. These parameters went stable when ΔPt was more than 1000 Pa. These results provided theoretical references for the research and design of the pulse-jet cleaning dust collectors.
2021, 39(8): 119-124,130.
doi: 10.13205/j.hjgc.202108016
Abstract:
In order to accurately obtain the gas-liquid two-phase reaction characteristics of the two-stage series tower desulfurization system, the gas-liquid two-phase flow and heat transfer process in the spray section of the double tower series wet desulfurization tower in a power plant were numerically simulated by using the step-by-step method and the self-developed tray model. A new system evaluation index was used to evaluate the desulfurization system, and the desulfurization system was optimized and evaluated by numerical simulation. The calculation results showed that no matter the pre washing tower or the absorption tower, the design of adding tray and efficiency ring reasonably could obtain better performance on the basis of opening less spray layer, which was conducive to reaching the higher standard of desulfurization, and reducing the amount of circulating slurry as well as reducing the pressure drop of the whole system of desulfurization tower and the power consumption.
In order to accurately obtain the gas-liquid two-phase reaction characteristics of the two-stage series tower desulfurization system, the gas-liquid two-phase flow and heat transfer process in the spray section of the double tower series wet desulfurization tower in a power plant were numerically simulated by using the step-by-step method and the self-developed tray model. A new system evaluation index was used to evaluate the desulfurization system, and the desulfurization system was optimized and evaluated by numerical simulation. The calculation results showed that no matter the pre washing tower or the absorption tower, the design of adding tray and efficiency ring reasonably could obtain better performance on the basis of opening less spray layer, which was conducive to reaching the higher standard of desulfurization, and reducing the amount of circulating slurry as well as reducing the pressure drop of the whole system of desulfurization tower and the power consumption.
2021, 39(8): 125-130.
doi: 10.13205/j.hjgc.202108017
Abstract:
The process of zinc electrolysis produced a lot of harmful particles and acid mist, effective controlling of these particles and acid mist could improve the occupational health of workers in the workshop and the surrounding atmospheric environment. Based on the pilot experiment, the ultrasonic technology was reformed on the basis of the traditional electrolysis system. The emission reduction efficiency of ultrasonic technology on the particles and acid mist produced in the process of zinc electrolysis was investigated, and the comprehensive influence of ultrasonic technology on the production indexes of zinc electrolysis was analyzed, such as current efficiency, energy consumption and zinc product quality. The results showed that ultrasonic technology could reduce the particulate matter and acid mist by 44.4% and 51.4% respectively. At the same time, the introduction of ultrasonic technology improved some production parameters: increasing current efficiency by 22.5%, and reducing electrolysis energy consumption by 39.6%. Therefore, ultrasonic technology had a significant effect on reducing particulate matter and acid mist from the actual production source of zinc electrolysis, which provided an effective basis for the application of ultrasonic technology in the actual production of zinc electrolysis to reduce the particulate matters.
The process of zinc electrolysis produced a lot of harmful particles and acid mist, effective controlling of these particles and acid mist could improve the occupational health of workers in the workshop and the surrounding atmospheric environment. Based on the pilot experiment, the ultrasonic technology was reformed on the basis of the traditional electrolysis system. The emission reduction efficiency of ultrasonic technology on the particles and acid mist produced in the process of zinc electrolysis was investigated, and the comprehensive influence of ultrasonic technology on the production indexes of zinc electrolysis was analyzed, such as current efficiency, energy consumption and zinc product quality. The results showed that ultrasonic technology could reduce the particulate matter and acid mist by 44.4% and 51.4% respectively. At the same time, the introduction of ultrasonic technology improved some production parameters: increasing current efficiency by 22.5%, and reducing electrolysis energy consumption by 39.6%. Therefore, ultrasonic technology had a significant effect on reducing particulate matter and acid mist from the actual production source of zinc electrolysis, which provided an effective basis for the application of ultrasonic technology in the actual production of zinc electrolysis to reduce the particulate matters.
2021, 39(8): 131-135.
doi: 10.13205/j.hjgc.202108018
Abstract:
The changes in the load of coal-fired power plant units are closely related to the various parameters of the selective catalytic reduction (SCR) system (temperature, oxygen content, nitrogen oxide concentration, SO2/SO3 conversion rate), and the level of each parameter directly affects the operation of the unit. In this paper, based on the field measurement data of 5 different working conditions (30%, 50%, 70%, 80%, 100%) of 3 groups of coal-fired power plants, the correlation analysis method was used to analyze the correlation of various parameters. The test results showed that the parameters that were positively correlated with the unit load were flue gas temperature and SO2/SO3 conversion rate; the parameters that were negatively correlated were the flue gas oxygen content and the SCR outlet nitrogen oxide concentration, but there was on significant correlation between the SCR inlet nitrogen oxide concentration and the unit load. It provided a reference for avoiding the phenomenon of no exceeding the standard under medium and low load.
The changes in the load of coal-fired power plant units are closely related to the various parameters of the selective catalytic reduction (SCR) system (temperature, oxygen content, nitrogen oxide concentration, SO2/SO3 conversion rate), and the level of each parameter directly affects the operation of the unit. In this paper, based on the field measurement data of 5 different working conditions (30%, 50%, 70%, 80%, 100%) of 3 groups of coal-fired power plants, the correlation analysis method was used to analyze the correlation of various parameters. The test results showed that the parameters that were positively correlated with the unit load were flue gas temperature and SO2/SO3 conversion rate; the parameters that were negatively correlated were the flue gas oxygen content and the SCR outlet nitrogen oxide concentration, but there was on significant correlation between the SCR inlet nitrogen oxide concentration and the unit load. It provided a reference for avoiding the phenomenon of no exceeding the standard under medium and low load.
2021, 39(8): 136-140,149.
doi: 10.13205/j.hjgc.202108019
Abstract:
The high-density polyethylene (HDPE) film of the anti-seepage layer of the landfill is easily damaged during operation. The online monitoring technology is used to determine the leakage area. After the medium on the membrane removed, the loopholes need to be accurately identified to provide a visual basis for welding process. Therefore, a machine vision-based damage identification method for impermeable layer in landfill was proposed. First, perform image processing on the sample set, including image grayscale, Gaussian filter denoising, point operation enhancement, threshold segmentation, and mathematical morphology processing. Secondly, the number of connected domains, damage area, circumference, major axis, minor axis and axial ratio were extracted according to the morphological features of the image. The retention method weas used to divide the sample set into a training set and a test set, and then the extracted features were used as the input for training SVM. Finally, multiple SVMs were used for classification and recognition. Experiments showed that the overall recognition accuracy of the classifier was 98.33%, among which the accuracy of block damage recognition was 98.24%, and the stitch damage was 98.42%.
The high-density polyethylene (HDPE) film of the anti-seepage layer of the landfill is easily damaged during operation. The online monitoring technology is used to determine the leakage area. After the medium on the membrane removed, the loopholes need to be accurately identified to provide a visual basis for welding process. Therefore, a machine vision-based damage identification method for impermeable layer in landfill was proposed. First, perform image processing on the sample set, including image grayscale, Gaussian filter denoising, point operation enhancement, threshold segmentation, and mathematical morphology processing. Secondly, the number of connected domains, damage area, circumference, major axis, minor axis and axial ratio were extracted according to the morphological features of the image. The retention method weas used to divide the sample set into a training set and a test set, and then the extracted features were used as the input for training SVM. Finally, multiple SVMs were used for classification and recognition. Experiments showed that the overall recognition accuracy of the classifier was 98.33%, among which the accuracy of block damage recognition was 98.24%, and the stitch damage was 98.42%.
2021, 39(8): 141-149.
doi: 10.13205/j.hjgc.202108020
Abstract:
Anaerobic digestion is a kind of biological treatment technology that can realize the recycling of organic solid waste. But there are main problems such as low efficiency of acid production and methane production at present. Studies showed that the addition of zero valent iron (Fe0) could effectively improve the anaerobic digestion performance of organic solid waste. This article reviewed the application of Fe0 in the process of anaerobic digestion of organic solid waste from the aspects of the effect of Fe0 on the acid production, methane production efficiency of organic solid waste, the combined effect of Fe0 and other additives. The mechanism of effect of Fe0 on the anaerobic digestion performance of organic solid waste mainly included reducing the system redox potential, corrosive hydrogen evolution, affecting the microbial community, affecting the activity of key enzymes. In addition, taking sulfide and antibiotic resistance genes (ARGs) as an example, the effect of Fe0 on removal of pollutants in the process of anaerobic digestion of organic solid waste was described. There are many deficiencies and challenges in the application of Fe0 in the anaerobic digestion of organic solid. The future application of Fe0 in the anaerobic digestion of organic solid waste was prospected from multiple perspectives.
Anaerobic digestion is a kind of biological treatment technology that can realize the recycling of organic solid waste. But there are main problems such as low efficiency of acid production and methane production at present. Studies showed that the addition of zero valent iron (Fe0) could effectively improve the anaerobic digestion performance of organic solid waste. This article reviewed the application of Fe0 in the process of anaerobic digestion of organic solid waste from the aspects of the effect of Fe0 on the acid production, methane production efficiency of organic solid waste, the combined effect of Fe0 and other additives. The mechanism of effect of Fe0 on the anaerobic digestion performance of organic solid waste mainly included reducing the system redox potential, corrosive hydrogen evolution, affecting the microbial community, affecting the activity of key enzymes. In addition, taking sulfide and antibiotic resistance genes (ARGs) as an example, the effect of Fe0 on removal of pollutants in the process of anaerobic digestion of organic solid waste was described. There are many deficiencies and challenges in the application of Fe0 in the anaerobic digestion of organic solid. The future application of Fe0 in the anaerobic digestion of organic solid waste was prospected from multiple perspectives.
2021, 39(8): 150-155,216.
doi: 10.13205/j.hjgc.202108021
Abstract:
The utilization of waste resources can help solve many problems including environmental pollution and resource shortage. Due to the wide application and high added value of medium chain carboxylic acids(MCCAs),the chain elongation technology has attracted wide attention in recent years. Chain elongation process could convert various biological wastes into MCCAs by the metabolism of specific microorganisms. Firstly these functional microorganisms were comprehensively introduced. Then, the mechanism (β-reverse oxidation) and reactions of chain elongation were described in details. In recent years, there were several advancements in chain elongation such as bio-electrochemical system, product extraction technology. Then the principles, practical applications and research progresses of those technologies which was beneficial to improving the yield of caproic acid, optimizing the process flow and reducing the operation costs were systematically introduced. Finally, the advantages, challenges and promoting approaches of mentioned methods were summarized.
The utilization of waste resources can help solve many problems including environmental pollution and resource shortage. Due to the wide application and high added value of medium chain carboxylic acids(MCCAs),the chain elongation technology has attracted wide attention in recent years. Chain elongation process could convert various biological wastes into MCCAs by the metabolism of specific microorganisms. Firstly these functional microorganisms were comprehensively introduced. Then, the mechanism (β-reverse oxidation) and reactions of chain elongation were described in details. In recent years, there were several advancements in chain elongation such as bio-electrochemical system, product extraction technology. Then the principles, practical applications and research progresses of those technologies which was beneficial to improving the yield of caproic acid, optimizing the process flow and reducing the operation costs were systematically introduced. Finally, the advantages, challenges and promoting approaches of mentioned methods were summarized.
2021, 39(8): 156-164.
doi: 10.13205/j.hjgc.202108022
Abstract:
In this article, thermogrmetric analysis was used to study the pyrolysis characteristics of waste printed circuit boards (WPCBs) under different atmospheres (air and nitrogen) and with different catalysts (4A and 5A). Various comprehensive pyrolysis characteristic curves were calculated, and the pyrolysis kinetic equations were established. The experimental results indicated that there are three obvious weight loss peaks in the pyrolysis curve of WPCBs under air atmosphere, corresponding to the volatile emission and pyrolysis, the decomposition of refractory organic matter and the fixed carbon pyrolysis respectively. Then, the two obvious weight loss peaks appeared in the WPCBs combustion curve under air atmosphere, corresponding to the volatile emission and pyrolysis and the decomposition of refractory organic matters. In the atmosphere of air and nitrogen, with the addition of catalyst (4A and 5A), the weight loss peak of water precipitation in WPCBs pyrolysis characteristic curve was significantly enhanced, and the strength of volatilization analysis and weight loss peak of pyrolysis and decomposition of refractory organic matter was significantly reduced. Under nitrogen atmosphere, WPCBs pyrolysis had higher volatile characteristic index D, flammability index C and comprehensive combustion index S, while the burnout index Cb was smaller. Nevertheless, the apparent activation energy (Eav) of WPCBs pyrolysis under different atmosphere and catalyst conditions was calculated by using Coats-Redfern integral method. The Eav was 227.29 kJ/mol (air or nitrogen) and 72.35~115.99 kJ/mol (air/nitrogen+4A/5A). After correction, the average mass apparent activation energy Em was 76.38 kJ/mol (air), 115.09 kJ/mol (nitrogen), ≤47.26 kJ/mol (air/nitrogen+4A/5A). Consequently, the reaction mechanisms of the pre-peak of the first volatile stage could be described as f(α)=(1-α)0.5, while the post-peak of the first volatile, the pre-peak and post-peak of the second volatile stage and the fixed carbon combustion stage could be described as f(α)=(1-α)2.
In this article, thermogrmetric analysis was used to study the pyrolysis characteristics of waste printed circuit boards (WPCBs) under different atmospheres (air and nitrogen) and with different catalysts (4A and 5A). Various comprehensive pyrolysis characteristic curves were calculated, and the pyrolysis kinetic equations were established. The experimental results indicated that there are three obvious weight loss peaks in the pyrolysis curve of WPCBs under air atmosphere, corresponding to the volatile emission and pyrolysis, the decomposition of refractory organic matter and the fixed carbon pyrolysis respectively. Then, the two obvious weight loss peaks appeared in the WPCBs combustion curve under air atmosphere, corresponding to the volatile emission and pyrolysis and the decomposition of refractory organic matters. In the atmosphere of air and nitrogen, with the addition of catalyst (4A and 5A), the weight loss peak of water precipitation in WPCBs pyrolysis characteristic curve was significantly enhanced, and the strength of volatilization analysis and weight loss peak of pyrolysis and decomposition of refractory organic matter was significantly reduced. Under nitrogen atmosphere, WPCBs pyrolysis had higher volatile characteristic index D, flammability index C and comprehensive combustion index S, while the burnout index Cb was smaller. Nevertheless, the apparent activation energy (Eav) of WPCBs pyrolysis under different atmosphere and catalyst conditions was calculated by using Coats-Redfern integral method. The Eav was 227.29 kJ/mol (air or nitrogen) and 72.35~115.99 kJ/mol (air/nitrogen+4A/5A). After correction, the average mass apparent activation energy Em was 76.38 kJ/mol (air), 115.09 kJ/mol (nitrogen), ≤47.26 kJ/mol (air/nitrogen+4A/5A). Consequently, the reaction mechanisms of the pre-peak of the first volatile stage could be described as f(α)=(1-α)0.5, while the post-peak of the first volatile, the pre-peak and post-peak of the second volatile stage and the fixed carbon combustion stage could be described as f(α)=(1-α)2.
2021, 39(8): 165-172,226.
doi: 10.13205/j.hjgc.202108023
Abstract:
In order to further explore the impact of biochar on the change of available heavy metals in soil, this study mainly summarized the mechanism of biochar influencing available heavy metals from the two aspects of direct and indirect effects. The biochar affected the speciation of heavy metal in soil, because of its large specific surface area, abundant functional-groups and minerals, during which physical adsorption, electrostatic attraction, complexation, ion exchange, and cation-π coordination, and chemical precipitation were involved in the binding of heavy metal. This is referred to direct effect, while the other was named as indirect effect. The biochar affected the speciation of heavy metal in soil by changing the physical and chemical properties of soil as well as the diversity of microbial communities, in which the chemical and microbial mechanisms played an important role in the immobilization of heavy metal. Finally, the conclusion and prospect were put forward in order to provide theoretical basis for the potential application of biochar remediation technology for soil heavy metal pollution.
In order to further explore the impact of biochar on the change of available heavy metals in soil, this study mainly summarized the mechanism of biochar influencing available heavy metals from the two aspects of direct and indirect effects. The biochar affected the speciation of heavy metal in soil, because of its large specific surface area, abundant functional-groups and minerals, during which physical adsorption, electrostatic attraction, complexation, ion exchange, and cation-π coordination, and chemical precipitation were involved in the binding of heavy metal. This is referred to direct effect, while the other was named as indirect effect. The biochar affected the speciation of heavy metal in soil by changing the physical and chemical properties of soil as well as the diversity of microbial communities, in which the chemical and microbial mechanisms played an important role in the immobilization of heavy metal. Finally, the conclusion and prospect were put forward in order to provide theoretical basis for the potential application of biochar remediation technology for soil heavy metal pollution.
2021, 39(8): 173-178,187.
doi: 10.13205/j.hjgc.202108024
Abstract:
In this paper, the in-situ electrothermal desorption remediation technology was applied to a polycyclic aromatic hydrocarbon (PAHs) contaminated site in East China. The changes of key parameters such as heating temperature, heating time and gas phase extraction density during operation were systematically analyzed, and the operating parameters such as the remediation effect, extraction gas concentration and energy consumption were also analyzed. The results showed that the in situ electrothermal desorption had a good removal effect on PAHs. After 250 days of heating, the soil temperature of the site reached above 300 ℃, and the pollutant removal rate reached more than 99.99%. The concentration of soil pollutants after remediation was lower than the requirements of the target value of remediation. The heating temperature, heating time and gas phase extraction density of soil were the key factors affecting the effect of in-situ electrothermal desorption remediation, and the construction experience of reducing the cost of remediation was put forward, which could provide references for the promotion and engineering application of high-temperature in-situ electrothermal desorption.
In this paper, the in-situ electrothermal desorption remediation technology was applied to a polycyclic aromatic hydrocarbon (PAHs) contaminated site in East China. The changes of key parameters such as heating temperature, heating time and gas phase extraction density during operation were systematically analyzed, and the operating parameters such as the remediation effect, extraction gas concentration and energy consumption were also analyzed. The results showed that the in situ electrothermal desorption had a good removal effect on PAHs. After 250 days of heating, the soil temperature of the site reached above 300 ℃, and the pollutant removal rate reached more than 99.99%. The concentration of soil pollutants after remediation was lower than the requirements of the target value of remediation. The heating temperature, heating time and gas phase extraction density of soil were the key factors affecting the effect of in-situ electrothermal desorption remediation, and the construction experience of reducing the cost of remediation was put forward, which could provide references for the promotion and engineering application of high-temperature in-situ electrothermal desorption.
2021, 39(8): 179-187.
doi: 10.13205/j.hjgc.202108025
Abstract:
The charring process and mechanism of traditional charring materials such as coke, activated carbon and biochar have been studied thoroughly. Charring reaction during soil thermal treatment process has an important influence on soil reuse. However, little attention has been paid on and its mechanism is unclear, so it is urgent to strengthen the related research. In order to refer to the achievements and experience of the traditional charring process, this paper discussed the preparation process and application of charring materials, the characterization methods of charring reaction process and the physicochemical properties of charring products, and the influencing factors of charring reaction process (charring methods, parameters, minerals and additives, etc.), as well as the guidance for the study on soil thermal treatment charring. Finally, several aspects were put forward during soil thermal treatment charring. The results showed that the charring characterization method could be used to analyse the charring behaviors of soil organic pollutants and identify the charring products. The yield and properties of charring products were related to many factors, and could be used to analyse the effects of soil thermal treatment conditions on charring behaviors.
The charring process and mechanism of traditional charring materials such as coke, activated carbon and biochar have been studied thoroughly. Charring reaction during soil thermal treatment process has an important influence on soil reuse. However, little attention has been paid on and its mechanism is unclear, so it is urgent to strengthen the related research. In order to refer to the achievements and experience of the traditional charring process, this paper discussed the preparation process and application of charring materials, the characterization methods of charring reaction process and the physicochemical properties of charring products, and the influencing factors of charring reaction process (charring methods, parameters, minerals and additives, etc.), as well as the guidance for the study on soil thermal treatment charring. Finally, several aspects were put forward during soil thermal treatment charring. The results showed that the charring characterization method could be used to analyse the charring behaviors of soil organic pollutants and identify the charring products. The yield and properties of charring products were related to many factors, and could be used to analyse the effects of soil thermal treatment conditions on charring behaviors.
2021, 39(8): 188-196.
doi: 10.13205/j.hjgc.202108026
Abstract:
In order to explore the degree of biodegradation and analyze the possibility of microbial remediation in the heterogeneous site contaminated by petroleum hydrocarbon, the upstream zone of the Chaobai River was selected as a typical research area. Under the control of an alluvial fan, the research area was characterized by a strong heterogeneity and a deep underground water depth. High-throughput sequencing analysis and microbial degradation column experiment were carried out by collecting samples from the contaminated sites. High-throughput sequencing results showed that Firimicutes (40.1%) was the dominant phylum and Paenisporosarcina (34.8%) was the dominant genus in uncontaminated area (T1). The dominant phylum identified in other samples of the site was Proteobacteria (35.1%~52.2%) and the dominant genus was Bacillius (7.7%~16.8%). Petroleum hydrocarbon pollutants greatly changed the microbial community structure and diversity of the region, and burial depth and water bearing conditions were significant influencing factors. The results of the column experiment of indoor microbial petroleum hydrocarbon degradation showed that adsorption was the main fate of petroleum hydrocarbon pollutants in the initial stage. The microbial degradation became stronger in the stage of 0~200 h, which played a leading role of this stage but the removal rate was lower than the adsorption. The results showed that the proportion and number of the dominant bacteria of petroleum hydrocarbon degradation were both low in the heterogeneous sites contaminated by petroleum hydrocarbon, and the microbial degradation was weak under natural condition.
In order to explore the degree of biodegradation and analyze the possibility of microbial remediation in the heterogeneous site contaminated by petroleum hydrocarbon, the upstream zone of the Chaobai River was selected as a typical research area. Under the control of an alluvial fan, the research area was characterized by a strong heterogeneity and a deep underground water depth. High-throughput sequencing analysis and microbial degradation column experiment were carried out by collecting samples from the contaminated sites. High-throughput sequencing results showed that Firimicutes (40.1%) was the dominant phylum and Paenisporosarcina (34.8%) was the dominant genus in uncontaminated area (T1). The dominant phylum identified in other samples of the site was Proteobacteria (35.1%~52.2%) and the dominant genus was Bacillius (7.7%~16.8%). Petroleum hydrocarbon pollutants greatly changed the microbial community structure and diversity of the region, and burial depth and water bearing conditions were significant influencing factors. The results of the column experiment of indoor microbial petroleum hydrocarbon degradation showed that adsorption was the main fate of petroleum hydrocarbon pollutants in the initial stage. The microbial degradation became stronger in the stage of 0~200 h, which played a leading role of this stage but the removal rate was lower than the adsorption. The results showed that the proportion and number of the dominant bacteria of petroleum hydrocarbon degradation were both low in the heterogeneous sites contaminated by petroleum hydrocarbon, and the microbial degradation was weak under natural condition.
2021, 39(8): 197-202,44.
doi: 10.13205/j.hjgc.202108027
Abstract:
As a typical sponge city infrastructure, permeable pavement has produced various environmental benefits such as urban rainwater reduction and water quality purification. However, in the process of material preparation, construction, maintenance and management, permeable pavement increased resource and energy consumption compared with the traditional pavement. It is urgent to apply the systematic analysis method of life cycle to carry out a comprehensive assessment of the resource and environmental benefits of permeable pavement. Through literature review, this study summarized the status and challenges of LCA application to permeable pavement assessment, and proposed corresponding countermeasures: incorporating the operation and maintenance stage into the boundary of the assessment system will help improve the comprehensiveness of the resource and environmental evaluation of permeable pavement; in view of the fact that the results of LCA are difficult to guide the engineering design, it was suggested to combine LCA with building information model to optimize the green design of permeable pavement; in view of the problems of life cycle environmental impact assessment methods such as the dynamic changes of permeation effect, it was recommended to introduce hydrological models into the overall assessment method. Through the improvement of the above perspective, the LCA method was expected to provide reference and optimization scheme for the whole process of policy-making, planning and design, construction and maintenance of permeable pavement, and help the construction of sponge city and the healthy development of urban ecosystem.
As a typical sponge city infrastructure, permeable pavement has produced various environmental benefits such as urban rainwater reduction and water quality purification. However, in the process of material preparation, construction, maintenance and management, permeable pavement increased resource and energy consumption compared with the traditional pavement. It is urgent to apply the systematic analysis method of life cycle to carry out a comprehensive assessment of the resource and environmental benefits of permeable pavement. Through literature review, this study summarized the status and challenges of LCA application to permeable pavement assessment, and proposed corresponding countermeasures: incorporating the operation and maintenance stage into the boundary of the assessment system will help improve the comprehensiveness of the resource and environmental evaluation of permeable pavement; in view of the fact that the results of LCA are difficult to guide the engineering design, it was suggested to combine LCA with building information model to optimize the green design of permeable pavement; in view of the problems of life cycle environmental impact assessment methods such as the dynamic changes of permeation effect, it was recommended to introduce hydrological models into the overall assessment method. Through the improvement of the above perspective, the LCA method was expected to provide reference and optimization scheme for the whole process of policy-making, planning and design, construction and maintenance of permeable pavement, and help the construction of sponge city and the healthy development of urban ecosystem.
2021, 39(8): 203-210,164.
doi: 10.13205/j.hjgc.202108028
Abstract:
Concentrations and speciation characteristics of arsenic and mercury in 40 surface soil samples around a gold mining area in Pinggu District of Beijing were determined. The pollution and ecological risk of arsenic and mercury were evaluated by the Ratio of Secondary Phase to Primary Phase (RSP) and Risk Assessment Code (RAC). The results showed that the average concentrations of arsenic and mercury in the soil exceeded the background values of soil, by 3.94~13.24 times and 11~41.33 times respectively; arsenic and mercury were primarily dominated by residual fraction, in addition to the residual fractions, arsenic in the soil of mining gully and tailings pond was bound to the Fe-Mn oxides, whereas mercury in the soil downstream of mining gully and outside the tailings pond was bound to the carbonate and the organics; the results of the pollution and ecological risk showed that the pollution degree of arsenic and mercury in the soil of mining gully and downstream was relatively lower, in the soil of the study area arsenic and mercury were at lower risk; in the soil of mining gully, YZ tailings pond and JHH tailings pond mercury were at high and extremely high risk, respectively, which should be paid attention to. The results provided a reference for treating arsenic and mercury pollution in the soil around the gold mining area.
Concentrations and speciation characteristics of arsenic and mercury in 40 surface soil samples around a gold mining area in Pinggu District of Beijing were determined. The pollution and ecological risk of arsenic and mercury were evaluated by the Ratio of Secondary Phase to Primary Phase (RSP) and Risk Assessment Code (RAC). The results showed that the average concentrations of arsenic and mercury in the soil exceeded the background values of soil, by 3.94~13.24 times and 11~41.33 times respectively; arsenic and mercury were primarily dominated by residual fraction, in addition to the residual fractions, arsenic in the soil of mining gully and tailings pond was bound to the Fe-Mn oxides, whereas mercury in the soil downstream of mining gully and outside the tailings pond was bound to the carbonate and the organics; the results of the pollution and ecological risk showed that the pollution degree of arsenic and mercury in the soil of mining gully and downstream was relatively lower, in the soil of the study area arsenic and mercury were at lower risk; in the soil of mining gully, YZ tailings pond and JHH tailings pond mercury were at high and extremely high risk, respectively, which should be paid attention to. The results provided a reference for treating arsenic and mercury pollution in the soil around the gold mining area.
2021, 39(8): 211-216.
doi: 10.13205/j.hjgc.202108029
Abstract:
Taking the leftover plot after the relocation of an abandoned dye factory in Jiangsu Province as the research object, the Nemero comprehensive pollution index method was used to assess the pollution degree of organic pollutants on the site, and the kriging interpolation method in Surfer software was used to simulate and analyze the spatial distribution of health risks of organic pollution factors. The results showed that the main pollutants exceeding standard in this site were chloroform and benzo (a) pyrene. The production workshop was the main polluted area. The maximum depth exceeding the standard was 12 m. Benzo (a) pyrene had a high carcinogenic risk to the exposed people in 1.5 m and 3.0 m deep soils, and chloroform had a high carcinogenic risk in 6 m and 12 m deep soils, but their hazard quotients in each layer were less than 1, so the site soil needed to be repaired before development and utilization.
Taking the leftover plot after the relocation of an abandoned dye factory in Jiangsu Province as the research object, the Nemero comprehensive pollution index method was used to assess the pollution degree of organic pollutants on the site, and the kriging interpolation method in Surfer software was used to simulate and analyze the spatial distribution of health risks of organic pollution factors. The results showed that the main pollutants exceeding standard in this site were chloroform and benzo (a) pyrene. The production workshop was the main polluted area. The maximum depth exceeding the standard was 12 m. Benzo (a) pyrene had a high carcinogenic risk to the exposed people in 1.5 m and 3.0 m deep soils, and chloroform had a high carcinogenic risk in 6 m and 12 m deep soils, but their hazard quotients in each layer were less than 1, so the site soil needed to be repaired before development and utilization.
2021, 39(8): 217-226.
doi: 10.13205/j.hjgc.202108030
Abstract:
In view of the lack of literature in monitoring of CO2 leakage into groundwater and the demand of the monitoring of CO2-EOR and storage projects in the Loess Tableland Region in the Ordos Basin, in this study, based on comprehensive characterization of the potential CO2 leakage into groundwater and identification of the spatial migration and time response characteristics of CO2 leakage into groundwater, a full-time and three-dimensional monitoring system was established for monitoring CO2 leakage into groundwater associated with CO2-EOR process in Loess Tableland Region. The result indicated that, affected by topography and soil characteristics, the potential CO2 leakage into groundwater featured with multiple leakage sources, including caprock breakthrough, shaft side leakage, rainfall infiltration and surface runoff recharge. The migration of CO2 leaked into the groundwater were characterized with quick diffusion in the vertical direction, slowly spread out in the horizontal direction, and movement along with water flow to downstream. The time response characteristics were also identified with seven indicators to CO2 leakage into groundwater, such as the increase of CO2 concentration, conductivity, HCO3- concentration, temperature and pressure, the decrease of pH value and the variation of Ca2+ and Mg2+ concentrations. The developed monitoring system reflecting above characteristics could provide solid support for the monitoring of CO2-EOR and storage in Loess Tableland Region.
In view of the lack of literature in monitoring of CO2 leakage into groundwater and the demand of the monitoring of CO2-EOR and storage projects in the Loess Tableland Region in the Ordos Basin, in this study, based on comprehensive characterization of the potential CO2 leakage into groundwater and identification of the spatial migration and time response characteristics of CO2 leakage into groundwater, a full-time and three-dimensional monitoring system was established for monitoring CO2 leakage into groundwater associated with CO2-EOR process in Loess Tableland Region. The result indicated that, affected by topography and soil characteristics, the potential CO2 leakage into groundwater featured with multiple leakage sources, including caprock breakthrough, shaft side leakage, rainfall infiltration and surface runoff recharge. The migration of CO2 leaked into the groundwater were characterized with quick diffusion in the vertical direction, slowly spread out in the horizontal direction, and movement along with water flow to downstream. The time response characteristics were also identified with seven indicators to CO2 leakage into groundwater, such as the increase of CO2 concentration, conductivity, HCO3- concentration, temperature and pressure, the decrease of pH value and the variation of Ca2+ and Mg2+ concentrations. The developed monitoring system reflecting above characteristics could provide solid support for the monitoring of CO2-EOR and storage in Loess Tableland Region.
2021, 39(8): 227-233.
doi: 10.13205/j.hjgc.202108031
Abstract:
Flow is one of the important indicators for online monitoring of rural sewage treatment facilities. Based on the conductive characteristics of rural domestic sewage, this study explored a new method for online monitoring the flow of rural domestic sewage. The designed online flow monitoring setup was mainly divided into two parts, a PAP metering tank and a conductivity level gauge (CLG). The PAP metering tank could convert the flow data measurement into liquid level data measurement. The CLG was made up by a measuring electrode and a reference electrode. The study found that the setup had the best performance when it was powered by a 400 Hz frequency AC source and branches of both the measuring electrode, and the reference electrode were connected in series with a 10 kΩ resistor. After laboratory calibration, the average relative error of the CLG could achieve 3.49%. The median measurement error was ±0.3 cm and the measurement range was 2.1~19.2 cm. After application of online flow monitoring setup, it was found that the daily flow data monitored by the prototype and other flow meters were significantly correlated at 0.01 level (both sides). Therefore, the method put forward by this study has good feasibility in actual application process and can realize remote online flow monitoring.
Flow is one of the important indicators for online monitoring of rural sewage treatment facilities. Based on the conductive characteristics of rural domestic sewage, this study explored a new method for online monitoring the flow of rural domestic sewage. The designed online flow monitoring setup was mainly divided into two parts, a PAP metering tank and a conductivity level gauge (CLG). The PAP metering tank could convert the flow data measurement into liquid level data measurement. The CLG was made up by a measuring electrode and a reference electrode. The study found that the setup had the best performance when it was powered by a 400 Hz frequency AC source and branches of both the measuring electrode, and the reference electrode were connected in series with a 10 kΩ resistor. After laboratory calibration, the average relative error of the CLG could achieve 3.49%. The median measurement error was ±0.3 cm and the measurement range was 2.1~19.2 cm. After application of online flow monitoring setup, it was found that the daily flow data monitored by the prototype and other flow meters were significantly correlated at 0.01 level (both sides). Therefore, the method put forward by this study has good feasibility in actual application process and can realize remote online flow monitoring.
