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2021 Vol. 39, No. 12
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2021, 39(12): 1-9,70.
doi: 10.13205/j.hjgc.202112001
Abstract:
At present, micro-plastics pollution has become a global environmental problem. In recent years, researches on micro-plastics mainly focused on the marine environment, but researches on freshwater environment were relatively scarce. Based on the review of the source-sink relationship and migration process of micro-plastics in freshwater environment, this paper discussed the way of aquatic organisms ingesting micro-plastics, its eco-toxicological effect and mechanism. As results, the main ways for aquatic organisms to ingest micro-plastics were ingestion, gill respiration or food chain transmission. After entering the organism, micro-plastics could migrate and accumulate in the gills, intestines, liver, brain and muscles. The eco-toxicity of micro-plastics included affecting gene expression, inhibiting enzyme activity, causing metabolic disorders, organ tissue pathology and inflammation, producing neurotoxins, reducing survival rates, and interfering with normal behavior, etc. In addition, the existing problems in researches of micro-plastics in freshwater environment were summarized, and the corresponding suggestions were put forward. This article could provide scientific guidance for the studies on ecological effects of micro-plastics and the interactive effects of other environmental issues in freshwater environment.
At present, micro-plastics pollution has become a global environmental problem. In recent years, researches on micro-plastics mainly focused on the marine environment, but researches on freshwater environment were relatively scarce. Based on the review of the source-sink relationship and migration process of micro-plastics in freshwater environment, this paper discussed the way of aquatic organisms ingesting micro-plastics, its eco-toxicological effect and mechanism. As results, the main ways for aquatic organisms to ingest micro-plastics were ingestion, gill respiration or food chain transmission. After entering the organism, micro-plastics could migrate and accumulate in the gills, intestines, liver, brain and muscles. The eco-toxicity of micro-plastics included affecting gene expression, inhibiting enzyme activity, causing metabolic disorders, organ tissue pathology and inflammation, producing neurotoxins, reducing survival rates, and interfering with normal behavior, etc. In addition, the existing problems in researches of micro-plastics in freshwater environment were summarized, and the corresponding suggestions were put forward. This article could provide scientific guidance for the studies on ecological effects of micro-plastics and the interactive effects of other environmental issues in freshwater environment.
2021, 39(12): 10-17,37.
doi: 10.13205/j.hjgc.202112002
Abstract:
Microbiological index is important to water safety, while the measurement of pathogenic bacteria in water is not included in the water quality monitoring due to the technique barrier. Most water quality standards contain only indicator microorganisms. However, the correlation between these indicators and real pathogens is not good enough to guarantee the safety. Therefore, developing fast and simple pathogen detection technologies is the key to improve microbiological monitoring in water. Loop-mediated isothermal amplification is a fast PCR technology to detect DNA independent of expensive PCR machine. This study attempted to detect 8 prevalent indicators and pathogenic bacteria: total coliform, Salmonella enterica, Shigella flexneri, Escherichia coli O157∶H7, Yesinia enterocolitica, Legionella pneumophila, Pseudomonas aeruginosa, Mycobacterium tuberculosis, by LAMP. The primers and PCR conditions of five of them were successfully optimized. The sensitivity of LAMP was to detect 100 gene copies within 45 minutes, and this technology can be applied in the detection of pathogens in raw wastewater.
Microbiological index is important to water safety, while the measurement of pathogenic bacteria in water is not included in the water quality monitoring due to the technique barrier. Most water quality standards contain only indicator microorganisms. However, the correlation between these indicators and real pathogens is not good enough to guarantee the safety. Therefore, developing fast and simple pathogen detection technologies is the key to improve microbiological monitoring in water. Loop-mediated isothermal amplification is a fast PCR technology to detect DNA independent of expensive PCR machine. This study attempted to detect 8 prevalent indicators and pathogenic bacteria: total coliform, Salmonella enterica, Shigella flexneri, Escherichia coli O157∶H7, Yesinia enterocolitica, Legionella pneumophila, Pseudomonas aeruginosa, Mycobacterium tuberculosis, by LAMP. The primers and PCR conditions of five of them were successfully optimized. The sensitivity of LAMP was to detect 100 gene copies within 45 minutes, and this technology can be applied in the detection of pathogens in raw wastewater.
2021, 39(12): 18-24.
doi: 10.13205/j.hjgc.202112003
Abstract:
The sewage flow and water quality indexes in the drainage pipe networks of three typical residential areas in the Tuandao region of Qingdao were monitored and measured for one year(from October 2019 to October 2020) to investigate the variation law of sewage flow and pollutants. The pollution production coefficient, variation coefficient, and correlation coefficient of the pollutants were calculated. The maximum daily pollutant concentration was mainly due to the low flow at night and pollutant deposition beginning at 7:00 am. At 7:00 am, the flow accelerated and scoured the pipe network, collecting high concentration pollutants. Pollutant fluctuation coefficients were observed less than 15%, indicating that the concentration was reasonably steady. The chemical oxygen demand(COD) pollution production coefficient was 108 g/(person·d), which was much higher than in the similar cities. The correlation coefficient between wastewater flow and COD, biochemical oxygen demand(BOD5), and suspended solid(SS) was high and indicated a strong synergistic tendency. However, there was no significant link between NH4+-N and total nitrogen(TN). This research provided an appropriate collection of data on the changing laws of wastewater flow and quality in the Qingdao Tuandao drainage system for process design and operation management of municipal wastewater treatment plants.
The sewage flow and water quality indexes in the drainage pipe networks of three typical residential areas in the Tuandao region of Qingdao were monitored and measured for one year(from October 2019 to October 2020) to investigate the variation law of sewage flow and pollutants. The pollution production coefficient, variation coefficient, and correlation coefficient of the pollutants were calculated. The maximum daily pollutant concentration was mainly due to the low flow at night and pollutant deposition beginning at 7:00 am. At 7:00 am, the flow accelerated and scoured the pipe network, collecting high concentration pollutants. Pollutant fluctuation coefficients were observed less than 15%, indicating that the concentration was reasonably steady. The chemical oxygen demand(COD) pollution production coefficient was 108 g/(person·d), which was much higher than in the similar cities. The correlation coefficient between wastewater flow and COD, biochemical oxygen demand(BOD5), and suspended solid(SS) was high and indicated a strong synergistic tendency. However, there was no significant link between NH4+-N and total nitrogen(TN). This research provided an appropriate collection of data on the changing laws of wastewater flow and quality in the Qingdao Tuandao drainage system for process design and operation management of municipal wastewater treatment plants.
2021, 39(12): 25-30.
doi: 10.13205/j.hjgc.202112004
Abstract:
The low pollutants concentration of influent water from urban wastewater treatment plants is one of the key problems to be solved for improving quality and efficiency of sewage treatment. Taking a sewage treatment plant in Wuxi City as an example, based on water quality analysis and research data, the cause of low concentration of influent water was analyzed by water balance triangle method and remedial measures were put forward. The results showed that 28.9% and 9.8% of groundwater or river water infiltration and rainwater infiltration were respectively in the inflow of sewage treatment plant. Leakage of sewage pipeline network and dilution of low concentration industrial wastewater were the main reasons for low concentration of water inflow in sunny days, while the main reasons for low concentration of water inflow in rainy days were mixed rainwater in pipeline network of residential quarter, then COD and BOD5 decreased by 65.4% and 52.9% respectively. In view of the above problems, this paper put forward four improvement measures, such as improving the drainage management system and mechanism, implementing the three pipe separation rectification for industrial enterprise drainage, refining the detection, investigation and effective repair of pipe network leakage, strengthening the acceptance and quality supervision of the pipe network, and reducing the water level of the pipe network to enhance influent concentrations of the urban wastewater treatment plant.
The low pollutants concentration of influent water from urban wastewater treatment plants is one of the key problems to be solved for improving quality and efficiency of sewage treatment. Taking a sewage treatment plant in Wuxi City as an example, based on water quality analysis and research data, the cause of low concentration of influent water was analyzed by water balance triangle method and remedial measures were put forward. The results showed that 28.9% and 9.8% of groundwater or river water infiltration and rainwater infiltration were respectively in the inflow of sewage treatment plant. Leakage of sewage pipeline network and dilution of low concentration industrial wastewater were the main reasons for low concentration of water inflow in sunny days, while the main reasons for low concentration of water inflow in rainy days were mixed rainwater in pipeline network of residential quarter, then COD and BOD5 decreased by 65.4% and 52.9% respectively. In view of the above problems, this paper put forward four improvement measures, such as improving the drainage management system and mechanism, implementing the three pipe separation rectification for industrial enterprise drainage, refining the detection, investigation and effective repair of pipe network leakage, strengthening the acceptance and quality supervision of the pipe network, and reducing the water level of the pipe network to enhance influent concentrations of the urban wastewater treatment plant.
2021, 39(12): 31-37.
doi: 10.13205/j.hjgc.202112005
Abstract:
This work investigated the feasibility of using alkali-hydrolyzed residual activated sludge as a denitrification carbon source to treat ammonia wastewater with a low C/N ratio. Batch experimental results showed that, compared to glucose and methanol, the denitrification rate using sludge alkali-hydrolysate was increased by 25.3% and 23.7%, respectively. The optimal parameters for nitrogen removal through denitrification were C/N=5.5, T=35 ℃, initial pH=8, and HRT=5 h. Under this conditions, NO3--N was almost completely removed without NO2--N accumulated. Subsequently, the sludge alkali-hydrolysate was applied to an A/O process to treat actual ammonia wastewater with a low C/N ratio. The A/O process was operated in continuous mode, and the sludge alkali-hydrolysate was supplemented in the anaerobic tank with an influent C/N ratio of 5.5. The effluent monitoring results showed that the ρ(TN)<15 mg/L, ρ(NH4+-N)<5 mg/L with almost no NOx--N accumulation, which all reached the first-level A emission limiting value in Discharge Standard of Pollutants for Municipal Wastewater treatment Plant. This work revealed that the sludge alkali-hydrolysate could be successfully used to treat actual ammonia wastewater with a low C/N ratio, and provided theoretical and practical support for treatment of nitrogen-containing wastewater and utilization of residual sludge.
This work investigated the feasibility of using alkali-hydrolyzed residual activated sludge as a denitrification carbon source to treat ammonia wastewater with a low C/N ratio. Batch experimental results showed that, compared to glucose and methanol, the denitrification rate using sludge alkali-hydrolysate was increased by 25.3% and 23.7%, respectively. The optimal parameters for nitrogen removal through denitrification were C/N=5.5, T=35 ℃, initial pH=8, and HRT=5 h. Under this conditions, NO3--N was almost completely removed without NO2--N accumulated. Subsequently, the sludge alkali-hydrolysate was applied to an A/O process to treat actual ammonia wastewater with a low C/N ratio. The A/O process was operated in continuous mode, and the sludge alkali-hydrolysate was supplemented in the anaerobic tank with an influent C/N ratio of 5.5. The effluent monitoring results showed that the ρ(TN)<15 mg/L, ρ(NH4+-N)<5 mg/L with almost no NOx--N accumulation, which all reached the first-level A emission limiting value in Discharge Standard of Pollutants for Municipal Wastewater treatment Plant. This work revealed that the sludge alkali-hydrolysate could be successfully used to treat actual ammonia wastewater with a low C/N ratio, and provided theoretical and practical support for treatment of nitrogen-containing wastewater and utilization of residual sludge.
2021, 39(12): 38-43,119.
doi: 10.13205/j.hjgc.202112006
Abstract:
River sediments are the transporters of pollutants. In this study, the effects of sediments particle size on hydraulic transport, content distribution, and speciation of arsenic in arsenic-bearing mine river were studied. The results showed that arsenic pollution was prominent in river sediments of the mine area; particle size affected not only the distribution and speciation of arsenic in various sediment particle size fractions but also their transport in water environment. The sediments were mainly composed of coarse sand and medium sand in the upstream and middle and upper reaches. In the upstream reaches, arsenic content in the sediments was 18.53 mg/kg, which mainly came from the primary minerals and existed in stable forms, such as well-crystallized hydrous Fe and Al oxides and residual. The content of arsenic reached 3492 mg/kg in the middle and upper reaches, which mainly came from oxide dissolution of arsenic-bearing ore and some original mineral. The amorphous and poorly-crystalline hydrous oxides of Fe and Al and residual were the main existing forms in coarse sand and medium sand components(73.90%), accounting for 83.71%, 83.82% of the total arsenic content, respectively. In fine sand, very fine sand and silty sand, the specific adsorption and amorphous and poorly-crystalline hydrous Fe and Al oxides were the main constituents, accounting for 58.72%, 58.51% and 73.10% respectively. The arsenic contents were still 371, 247 mg/kg in the sediments from middle and lower reaches of 2 km and 4 km away from the mine. The sediments existed mainly in fine sand, extremely fine sand and silt-sand, and predominant forms of arsenic were the specific adsorption and amorphous and poorly-crystalline hydrous Fe and Al oxides. Arsenic in the component less than 0.25 mm(fine sand, very fine sand, silted sand) was 1.5 times of that of the coarse sand component, and fine grain sediments played a leading role in the hydraulic transmission of arsenic. Therefore, the ecological control and soil and water conservation in the upper and middle reaches and the ecological dredging and rehabilitation of sediments in the downstream reach should be strengthened.
River sediments are the transporters of pollutants. In this study, the effects of sediments particle size on hydraulic transport, content distribution, and speciation of arsenic in arsenic-bearing mine river were studied. The results showed that arsenic pollution was prominent in river sediments of the mine area; particle size affected not only the distribution and speciation of arsenic in various sediment particle size fractions but also their transport in water environment. The sediments were mainly composed of coarse sand and medium sand in the upstream and middle and upper reaches. In the upstream reaches, arsenic content in the sediments was 18.53 mg/kg, which mainly came from the primary minerals and existed in stable forms, such as well-crystallized hydrous Fe and Al oxides and residual. The content of arsenic reached 3492 mg/kg in the middle and upper reaches, which mainly came from oxide dissolution of arsenic-bearing ore and some original mineral. The amorphous and poorly-crystalline hydrous oxides of Fe and Al and residual were the main existing forms in coarse sand and medium sand components(73.90%), accounting for 83.71%, 83.82% of the total arsenic content, respectively. In fine sand, very fine sand and silty sand, the specific adsorption and amorphous and poorly-crystalline hydrous Fe and Al oxides were the main constituents, accounting for 58.72%, 58.51% and 73.10% respectively. The arsenic contents were still 371, 247 mg/kg in the sediments from middle and lower reaches of 2 km and 4 km away from the mine. The sediments existed mainly in fine sand, extremely fine sand and silt-sand, and predominant forms of arsenic were the specific adsorption and amorphous and poorly-crystalline hydrous Fe and Al oxides. Arsenic in the component less than 0.25 mm(fine sand, very fine sand, silted sand) was 1.5 times of that of the coarse sand component, and fine grain sediments played a leading role in the hydraulic transmission of arsenic. Therefore, the ecological control and soil and water conservation in the upper and middle reaches and the ecological dredging and rehabilitation of sediments in the downstream reach should be strengthened.
2021, 39(12): 44-50.
doi: 10.13205/j.hjgc.202112007
Abstract:
The runoff detention tank plays an important role in peak flow control and combined sewer overflow pollution control, but the sedimentation characteristics of particles in the stormwater runoff detention tank are still lack of systematic study. Using computational fluid dynamics(CFD) simulation technology, the sedimentation characteristics of particles in the runoff detention tank under different structures and different working conditions were systematically studied. The simulation results showed that when the influent velocity increased from 0.276 m/s to 0.553 m/s, the particle removal rate of the detention tank with smooth bottom(typeⅠ), additional baffles(typeⅡ) and energy dissipating holes(type Ⅲ) decreased by 14.90%, 13.89% and 15.32%, respectively. When the particle size of influent increased from 0.075 mm to 0.15 mm, the particle removal rate increased by 9.10%, 62.48% and 36.65% in the detention tank of typeⅠ, typeⅡand type Ⅲ structure, respectively; when the influent particle concentration increased from 1000 mg/L to 2000 mg/L, the particle removal rate increased by 3.60%, 2.84% and 13.30% in the detention tank of typeⅠ, typeⅡ and type Ⅲ structure, respectively. The importance of different influencing factors on the water quality control in the typeⅠdetention tank was in sequence of influent velocity>particle size>influent particle concentration, and that on the water quality control in both the type Ⅱ and type Ⅲ detention tank were in sequence of particle size>influent velocity>influent particle concentration.
The runoff detention tank plays an important role in peak flow control and combined sewer overflow pollution control, but the sedimentation characteristics of particles in the stormwater runoff detention tank are still lack of systematic study. Using computational fluid dynamics(CFD) simulation technology, the sedimentation characteristics of particles in the runoff detention tank under different structures and different working conditions were systematically studied. The simulation results showed that when the influent velocity increased from 0.276 m/s to 0.553 m/s, the particle removal rate of the detention tank with smooth bottom(typeⅠ), additional baffles(typeⅡ) and energy dissipating holes(type Ⅲ) decreased by 14.90%, 13.89% and 15.32%, respectively. When the particle size of influent increased from 0.075 mm to 0.15 mm, the particle removal rate increased by 9.10%, 62.48% and 36.65% in the detention tank of typeⅠ, typeⅡand type Ⅲ structure, respectively; when the influent particle concentration increased from 1000 mg/L to 2000 mg/L, the particle removal rate increased by 3.60%, 2.84% and 13.30% in the detention tank of typeⅠ, typeⅡ and type Ⅲ structure, respectively. The importance of different influencing factors on the water quality control in the typeⅠdetention tank was in sequence of influent velocity>particle size>influent particle concentration, and that on the water quality control in both the type Ⅱ and type Ⅲ detention tank were in sequence of particle size>influent velocity>influent particle concentration.
2021, 39(12): 51-58,78.
doi: 10.13205/j.hjgc.202112008
Abstract:
Low-temperature environment is usually inevitable for the sewage biological treatment system, which seriously affects the microbial activity. How to improve the denitrification effect of microorganisms in low-temperature is an urgent problem. In this study, low-temperature nitrifying bacteria BC-15, SL-14 and MI-11, extracted from three different environments all had high nitrogen removal efficiency at 13 ℃, and all of them were identified as Acinetobacter sp. by 16S rDNA. There was no antagonistic reaction among the strains, and the best compound ratio was 1∶1∶1. Compared with sodium alginate-polyvinyl alcohol and sodium alginate-diatomite materials, the results showed that sodium alginate-diatomite materials had stronger immobilization and nitrification ability, and the best ratio of immobilization materials was 1% diatomite, 2% SA, 3% CaCl2 and 6% zeolite. The spheroidization, mass transfer and stability of the immobilized particles were all reliable. After immobilization, the acid and alkali tolerance of the strain was significantly enhanced, and the removal rate of ammonia nitrogen still reached 76.67% after 4 times of reuse, and the nitrification ability and structure were stable. The removal rate of ammonia nitrogen in real domestic sewage by immobilized particles reached 95.86%, showed high nitrification ability, and could raise the possibility for the practical engineering application of low temperature sewage treatment.
Low-temperature environment is usually inevitable for the sewage biological treatment system, which seriously affects the microbial activity. How to improve the denitrification effect of microorganisms in low-temperature is an urgent problem. In this study, low-temperature nitrifying bacteria BC-15, SL-14 and MI-11, extracted from three different environments all had high nitrogen removal efficiency at 13 ℃, and all of them were identified as Acinetobacter sp. by 16S rDNA. There was no antagonistic reaction among the strains, and the best compound ratio was 1∶1∶1. Compared with sodium alginate-polyvinyl alcohol and sodium alginate-diatomite materials, the results showed that sodium alginate-diatomite materials had stronger immobilization and nitrification ability, and the best ratio of immobilization materials was 1% diatomite, 2% SA, 3% CaCl2 and 6% zeolite. The spheroidization, mass transfer and stability of the immobilized particles were all reliable. After immobilization, the acid and alkali tolerance of the strain was significantly enhanced, and the removal rate of ammonia nitrogen still reached 76.67% after 4 times of reuse, and the nitrification ability and structure were stable. The removal rate of ammonia nitrogen in real domestic sewage by immobilized particles reached 95.86%, showed high nitrification ability, and could raise the possibility for the practical engineering application of low temperature sewage treatment.
2021, 39(12): 59-65,127.
doi: 10.13205/j.hjgc.202112009
Abstract:
Modified basalt fiber(MBF) is a new type of inorganic micron-sized fiber carrier. To investigate the bioaffinity of the MBF carrier and evaluate its feasibility in practical application, the extended DLVO theory was used to construct the dynamics model of the bacteria adhesion behaviors on MBF carrier, and the biological contact oxidation reactor filled with MBF carrier was operated to treat the synthetic municipal wastewater and evaluate its treatment efficiency. The results showed that there was no energy barrier between Bacillus subtilis(B. subtilis) and MBF, allowing B. subtilis strong adhesion onto MBF. Therefore, the MBF carrier had high microbial immobilization capacity. In addition, the biological contact oxidation reactor filled with the MBF carrier started up quickly and maintained long-term stable operation. The average removal efficiencies of COD, ammonia nitrogen and total nitrogen were up to 94%, 99.5% and 97%, respectively. Therefore, the MBF carrier has a promising applicability in engineering practice, which provides an alternative to conventional organic carrier.
Modified basalt fiber(MBF) is a new type of inorganic micron-sized fiber carrier. To investigate the bioaffinity of the MBF carrier and evaluate its feasibility in practical application, the extended DLVO theory was used to construct the dynamics model of the bacteria adhesion behaviors on MBF carrier, and the biological contact oxidation reactor filled with MBF carrier was operated to treat the synthetic municipal wastewater and evaluate its treatment efficiency. The results showed that there was no energy barrier between Bacillus subtilis(B. subtilis) and MBF, allowing B. subtilis strong adhesion onto MBF. Therefore, the MBF carrier had high microbial immobilization capacity. In addition, the biological contact oxidation reactor filled with the MBF carrier started up quickly and maintained long-term stable operation. The average removal efficiencies of COD, ammonia nitrogen and total nitrogen were up to 94%, 99.5% and 97%, respectively. Therefore, the MBF carrier has a promising applicability in engineering practice, which provides an alternative to conventional organic carrier.
2021, 39(12): 66-70.
doi: 10.13205/j.hjgc.202112010
Abstract:
The design capacity of the upgrading and extension of a wastewater treatment plant(WWTP) from Danjiangkou was 3.0×104 m3/d. Main indicators of the effluent quality met the class Ⅳ criteria in Environmental Quality Standard for Surface Water and TN concentration was less than 15 mg/L. A2/O(anaerobic/anoxic/oxic process)+MBR(membrane bioreactor) combined process served as the secondary treatment and realized the designed target with good treatment performance. The application of BIM(building information modeling) technology was introduced in combination with the design of MBR process, and the optimization proposal to the potential problems was provided based on the analysis results. Meanwhile, the solutions to some problems exposed during the practical operation were presented as well, such as the layout and lifting of the devices, sludge sedimentation and aeration, cavitation projection of reflux pumps, which could provide reference for the similar projects.
The design capacity of the upgrading and extension of a wastewater treatment plant(WWTP) from Danjiangkou was 3.0×104 m3/d. Main indicators of the effluent quality met the class Ⅳ criteria in Environmental Quality Standard for Surface Water and TN concentration was less than 15 mg/L. A2/O(anaerobic/anoxic/oxic process)+MBR(membrane bioreactor) combined process served as the secondary treatment and realized the designed target with good treatment performance. The application of BIM(building information modeling) technology was introduced in combination with the design of MBR process, and the optimization proposal to the potential problems was provided based on the analysis results. Meanwhile, the solutions to some problems exposed during the practical operation were presented as well, such as the layout and lifting of the devices, sludge sedimentation and aeration, cavitation projection of reflux pumps, which could provide reference for the similar projects.
2021, 39(12): 71-78.
doi: 10.13205/j.hjgc.202112011
Abstract:
The fractions distribution of sediment phosphorus is one of the important controlling factors of river endogenous release. In present study, the total phosphorus, inorganic phosphorus and organic phosphorus contents in surface sediments of Paihe River section, the clear water gallery of Yangtze-Huaihe Water Diversion, were determined. The organic phosphorus fractions were explored by the method of graded extraction, including labile organic phosphorus(LOP), moderately labile organic phosphorus(MLOP) and nonlabile organic phosphorus(NOP). And the spatial distribution characteristics of phosphorus fractions were further discussed. The results showed that the total phosphorus content in the surface sediments of Paihe River was 471.17~1509.58 mg/kg, among which the inorganic phosphorus content was 421.83~1325.17 mg/kg, and the organic phosphorus content was 103.29~221.79 mg/kg. Generally, the contents of organic phosphorus fractions followed the order of NOP>LOP>MLOP, and the content of MLOP and NOP were significantly higher in the downstream reach than in the middle and upper reach(P<0.05). The organic phosphorus fractions was related to the physical and chemical properties of sediments. NOP had significant positive correlation with cation exchange capacity(CEC)(P<0.05), MLOP and NOP had significant positive correlation with loss on ignition(LOI)(P<0.05), indicating that the variation of organic matter and CEC in sediments affected the distribution of organic phosphorus fractions. The results of this study indicated that the implementation of the Yangtze-Huaihe Water Diversion project may lead to the endogenous release of phosphorus in sediments. Therefore, after the project implemented, on the basis of reducing exogenous input and endogenous control, ecological monitoring should be strengthened and watershed intelligent management should be conducted.
The fractions distribution of sediment phosphorus is one of the important controlling factors of river endogenous release. In present study, the total phosphorus, inorganic phosphorus and organic phosphorus contents in surface sediments of Paihe River section, the clear water gallery of Yangtze-Huaihe Water Diversion, were determined. The organic phosphorus fractions were explored by the method of graded extraction, including labile organic phosphorus(LOP), moderately labile organic phosphorus(MLOP) and nonlabile organic phosphorus(NOP). And the spatial distribution characteristics of phosphorus fractions were further discussed. The results showed that the total phosphorus content in the surface sediments of Paihe River was 471.17~1509.58 mg/kg, among which the inorganic phosphorus content was 421.83~1325.17 mg/kg, and the organic phosphorus content was 103.29~221.79 mg/kg. Generally, the contents of organic phosphorus fractions followed the order of NOP>LOP>MLOP, and the content of MLOP and NOP were significantly higher in the downstream reach than in the middle and upper reach(P<0.05). The organic phosphorus fractions was related to the physical and chemical properties of sediments. NOP had significant positive correlation with cation exchange capacity(CEC)(P<0.05), MLOP and NOP had significant positive correlation with loss on ignition(LOI)(P<0.05), indicating that the variation of organic matter and CEC in sediments affected the distribution of organic phosphorus fractions. The results of this study indicated that the implementation of the Yangtze-Huaihe Water Diversion project may lead to the endogenous release of phosphorus in sediments. Therefore, after the project implemented, on the basis of reducing exogenous input and endogenous control, ecological monitoring should be strengthened and watershed intelligent management should be conducted.
2021, 39(12): 79-83,158.
doi: 10.13205/j.hjgc.202112012
Abstract:
Water quality safety early warning is of great significance for preventing water pollution accidents and ensuring water resources safety. The traditional water quality safety early warning model can only give early warning to the gradual water environmental pollution accidents or the water environmental pollution accidents that have already occurred and have obvious signs appearing, but cannot give effective early warning to the sudden water environmental pollution accidents without obvious signs. To solve this problem, the step idea of Petri net was effectively incorporated into the traditional evaluation index system, so as to realize the structural adjustment of the logical topology network of the model. Combined with the fuzzy comprehensive evaluation method and BP neural network, an early warning model which can timely reflect the sudden water environmental pollution accident was established. The model was applied to the study of water quality safety in Taihu Lake. The results showed that the model could accurately predict the occurrence of multiple bloom events in Taihu Lake, on the basis of incorporating the indexes of total nitrogen, total phosphorus and transparency into the step factors. The conclusion provided a new idea and theoretical basis for studying the early warning of water environmental pollution accidents.
Water quality safety early warning is of great significance for preventing water pollution accidents and ensuring water resources safety. The traditional water quality safety early warning model can only give early warning to the gradual water environmental pollution accidents or the water environmental pollution accidents that have already occurred and have obvious signs appearing, but cannot give effective early warning to the sudden water environmental pollution accidents without obvious signs. To solve this problem, the step idea of Petri net was effectively incorporated into the traditional evaluation index system, so as to realize the structural adjustment of the logical topology network of the model. Combined with the fuzzy comprehensive evaluation method and BP neural network, an early warning model which can timely reflect the sudden water environmental pollution accident was established. The model was applied to the study of water quality safety in Taihu Lake. The results showed that the model could accurately predict the occurrence of multiple bloom events in Taihu Lake, on the basis of incorporating the indexes of total nitrogen, total phosphorus and transparency into the step factors. The conclusion provided a new idea and theoretical basis for studying the early warning of water environmental pollution accidents.
2021, 39(12): 84-90,242.
doi: 10.13205/j.hjgc.202112013
Abstract:
The purpose of the study is to clarify the influencing factors of urban green space runoff production process, compare the principle and characteristics of different calculation of runoff coefficient. Taking the urban green space in Beijing as an example, the study used three kinds of methods: theoretical calculation, model simulation and experimental measurement to compare KW(kinematic wave) equation, SCS-CN(soil conservation service curve number) algorithm, Hydrus-1 D model and experimental measurement, to quantitative analysis of runoff production processes, influencing factors and corresponding runoff coefficients under different rainfall, soil and topographic condition. Experiments showed that rainfall(recurrence period), rain pattern, physical properties of soil(soil permeability, pre-wetting degree, etc.) and green slope all had great influence on the runoff production process. In different conditions and algorithms, the value range of green runoff coefficient was 0~0.53. The results showed that in engineering application, the suitable method and model parameters of runoff coefficient should be selected in combination with site conditions and design objectives, which could provide references for the study of runoff coefficients of urban green space in China.
The purpose of the study is to clarify the influencing factors of urban green space runoff production process, compare the principle and characteristics of different calculation of runoff coefficient. Taking the urban green space in Beijing as an example, the study used three kinds of methods: theoretical calculation, model simulation and experimental measurement to compare KW(kinematic wave) equation, SCS-CN(soil conservation service curve number) algorithm, Hydrus-1 D model and experimental measurement, to quantitative analysis of runoff production processes, influencing factors and corresponding runoff coefficients under different rainfall, soil and topographic condition. Experiments showed that rainfall(recurrence period), rain pattern, physical properties of soil(soil permeability, pre-wetting degree, etc.) and green slope all had great influence on the runoff production process. In different conditions and algorithms, the value range of green runoff coefficient was 0~0.53. The results showed that in engineering application, the suitable method and model parameters of runoff coefficient should be selected in combination with site conditions and design objectives, which could provide references for the study of runoff coefficients of urban green space in China.
2021, 39(12): 91-99,134.
doi: 10.13205/j.hjgc.202112014
Abstract:
Drug contamination caused by the overuse of antibiotics poses a potential threat to human health and ecosystems. Adsorption is one of the most effective methods to remove organic pollutants from the water environment, as a cheap and efficient adsorption material, adsorption properties of the biochar has been significantly improved after modification. The adsorption characteristics and mechanism of the modified biochar to antibiotics have been widely studied and applied. On the basis of a review on the preparation and modification technologies of biochars, this paper systematically discussed the progress and deficiency of the adsorption properties and mechanism of the modified biochar to typical antibiotic drugs, and analyzed the recycling and economic benefits of biochar, in order to provide guidance and reference for the research and development of new high-efficiency biochar adsorption mechanism and materials.
Drug contamination caused by the overuse of antibiotics poses a potential threat to human health and ecosystems. Adsorption is one of the most effective methods to remove organic pollutants from the water environment, as a cheap and efficient adsorption material, adsorption properties of the biochar has been significantly improved after modification. The adsorption characteristics and mechanism of the modified biochar to antibiotics have been widely studied and applied. On the basis of a review on the preparation and modification technologies of biochars, this paper systematically discussed the progress and deficiency of the adsorption properties and mechanism of the modified biochar to typical antibiotic drugs, and analyzed the recycling and economic benefits of biochar, in order to provide guidance and reference for the research and development of new high-efficiency biochar adsorption mechanism and materials.
2021, 39(12): 100-106.
doi: 10.13205/j.hjgc.202112015
Abstract:
In this study, three kinds of microbial carriers including porous polymer carriers(PPC), polyurethane(PU) and polypropylene(PP) were selected to compare and analyze the start-up performance, nitrogen removal performance and microbial community structure of mobile bed biofilm reactor(MBBR) with three carriers respectively. The results showed that when the influent ammonia concentration was 20 mg/L, PPC and PU carriers showed better film-hanging start-up performance and ammonia nitrogen removal performance. The average effluent ammonia nitrogen concentration was about 5 mg/L, while the average effluent ammonia nitrogen concentration of PP carrier was nearly 7 mg/L, and the removal stability was poor. In addition, denitrification effect of PU and PP carrier was not ideal, and the average concentration of effluent nitrate nitrogen was 6.07, 4.87 mg/L, respectively, much higher than PPC carrier(2.80 mg/L). The microbial sequencing results showed that the selection of microbial carriers had a certain degree of influence on microbial community structure of the MBBR process, but Proteobacteria and Bacteroidetes were always the most dominant bacterial species. Analysis at the level of genus indicated that Denitratisoma bacteria with high abundance existed on PPC carrier, and the unique structure and hydrophilicity of PPC carrier contributed to the creation of anoxic environment, and improved the overall Denitratisoma performance and stability of the reactor where it was located.
In this study, three kinds of microbial carriers including porous polymer carriers(PPC), polyurethane(PU) and polypropylene(PP) were selected to compare and analyze the start-up performance, nitrogen removal performance and microbial community structure of mobile bed biofilm reactor(MBBR) with three carriers respectively. The results showed that when the influent ammonia concentration was 20 mg/L, PPC and PU carriers showed better film-hanging start-up performance and ammonia nitrogen removal performance. The average effluent ammonia nitrogen concentration was about 5 mg/L, while the average effluent ammonia nitrogen concentration of PP carrier was nearly 7 mg/L, and the removal stability was poor. In addition, denitrification effect of PU and PP carrier was not ideal, and the average concentration of effluent nitrate nitrogen was 6.07, 4.87 mg/L, respectively, much higher than PPC carrier(2.80 mg/L). The microbial sequencing results showed that the selection of microbial carriers had a certain degree of influence on microbial community structure of the MBBR process, but Proteobacteria and Bacteroidetes were always the most dominant bacterial species. Analysis at the level of genus indicated that Denitratisoma bacteria with high abundance existed on PPC carrier, and the unique structure and hydrophilicity of PPC carrier contributed to the creation of anoxic environment, and improved the overall Denitratisoma performance and stability of the reactor where it was located.
2021, 39(12): 107-113,187.
doi: 10.13205/j.hjgc.202112016
Abstract:
The abatement kinetics and mechanism of acetamiprid were studied by ozonation, ultraviolet/ozone(UV/O3), and electro-peroxone(EP) in the groundwater and surface water. The electrical energy demands per order removal(EEO) of acetamiprid abatement by these processes were compared in two real water matrices. The second-order rate constants for the reaction of acetamiprid with ozone and hydroxyl radical(·OH) at pH of 7 were determined to be(0.05±0.01) mol/(L·s) and(2.8±0.2)×109 mol/(L·s), respectively. After 6 min ozone oxidation, the removal rates of acetamiprid in groundwater and surface water were only 26% and 64%. In contrast, UV/O3 and EP technology can completely remove acetamiprid from groundwater and surface water. The energy demands for 90% removal efficiency of acetamiprid were 0.11~0.27, 1.22~1.24, and 0.12~0.24 kW·h/m3 for ozonation, UV/O3, and EP processes, respectively. The results showed that the EP process was an energy-efficient alternative for the abatement of acetamiprid in water treatment.
The abatement kinetics and mechanism of acetamiprid were studied by ozonation, ultraviolet/ozone(UV/O3), and electro-peroxone(EP) in the groundwater and surface water. The electrical energy demands per order removal(EEO) of acetamiprid abatement by these processes were compared in two real water matrices. The second-order rate constants for the reaction of acetamiprid with ozone and hydroxyl radical(·OH) at pH of 7 were determined to be(0.05±0.01) mol/(L·s) and(2.8±0.2)×109 mol/(L·s), respectively. After 6 min ozone oxidation, the removal rates of acetamiprid in groundwater and surface water were only 26% and 64%. In contrast, UV/O3 and EP technology can completely remove acetamiprid from groundwater and surface water. The energy demands for 90% removal efficiency of acetamiprid were 0.11~0.27, 1.22~1.24, and 0.12~0.24 kW·h/m3 for ozonation, UV/O3, and EP processes, respectively. The results showed that the EP process was an energy-efficient alternative for the abatement of acetamiprid in water treatment.
2021, 39(12): 114-119.
doi: 10.13205/j.hjgc.202112017
Abstract:
Using graphene as the adsorbent, and reactive black KN-B as the target pollutant to simulate dye wastewater, the influencing factors of adsorption treatment of reactive black KN-B simulated dye wastewater and the adsorption behavior of reactive black KN-B on graphene surface were investigated. The results showed that under the optimum reaction condition of adding 2 g/L of graphene in 50 mL solution, pH value was 5.0, oscillating rate was 100 r/min, oscillating at 40 ℃ for 60 min, the removal rate of absorption 50 mg/L reactive black KN-B dye wastewater could reach 94%. It was found that Langmuir adsorption isotherm and quasi-second-order kinetics could be used to describe the adsorption behavior of reactive black KN-B on graphene surface, and then this course could be defined as monolayer chemisorption.
Using graphene as the adsorbent, and reactive black KN-B as the target pollutant to simulate dye wastewater, the influencing factors of adsorption treatment of reactive black KN-B simulated dye wastewater and the adsorption behavior of reactive black KN-B on graphene surface were investigated. The results showed that under the optimum reaction condition of adding 2 g/L of graphene in 50 mL solution, pH value was 5.0, oscillating rate was 100 r/min, oscillating at 40 ℃ for 60 min, the removal rate of absorption 50 mg/L reactive black KN-B dye wastewater could reach 94%. It was found that Langmuir adsorption isotherm and quasi-second-order kinetics could be used to describe the adsorption behavior of reactive black KN-B on graphene surface, and then this course could be defined as monolayer chemisorption.
SPATIAL AND TEMPORAL CHANGES OF AEROSOL IN YANGTZE RIVER DELTA AND ITS METEOROLOGICAL INTERPRETATION
2021, 39(12): 120-127.
doi: 10.13205/j.hjgc.202112018
Abstract:
Based on MODIS aerosol optical depth(AOD) data and meteorological observed data from 2008 to 2017, the spatial and temporal distribution of AOD in the Yangtze River Delta area was summarized, which was then explained by analyzing the correlation between AOD and meteorological factors. The results showed that: 1) the annual average AOD fluctuated periodically, which showed its peak value of 0.83 in 2011, and declined rapidly from 2014, with an obvious decrease of 22.8% in 2017 compared with 2014. In addition, the peak value of monthly mean AOD appeared in summer, which was mainly caused by the diffusion of large amount of sea salt aerosol particles and water vapor from the ocean in summer; 2) in terms of spatial distribution, the AOD high value in Yangtze River Delta mainly distributed in southern Jiangsu and Xuzhou area, and the area with AOD high value had gradually narrowed since 2014; the AOD of Zhejiang Province was significantly lower than the other areas, which was closely related to the high topography of Zhejiang Province; 3) the change of AOD had a good positive correlation with the temperature and relative humidity, but the correlation with wind speed was poor and complex, which may be affected by the uncertainty of wind direction. In summer, due to high temperature and humidity, most areas showed high AOD values, and the low temperature and air moisture content in winter caused low AOD. However, the contribution of solid particles to AOD was large in winter, so the change of AOD may reflect the air pollution in winter. The results can provide a reference for aerosol assessment, air quality attribution analysis and air quality improvement in the Yangtze River Delta in future.
Based on MODIS aerosol optical depth(AOD) data and meteorological observed data from 2008 to 2017, the spatial and temporal distribution of AOD in the Yangtze River Delta area was summarized, which was then explained by analyzing the correlation between AOD and meteorological factors. The results showed that: 1) the annual average AOD fluctuated periodically, which showed its peak value of 0.83 in 2011, and declined rapidly from 2014, with an obvious decrease of 22.8% in 2017 compared with 2014. In addition, the peak value of monthly mean AOD appeared in summer, which was mainly caused by the diffusion of large amount of sea salt aerosol particles and water vapor from the ocean in summer; 2) in terms of spatial distribution, the AOD high value in Yangtze River Delta mainly distributed in southern Jiangsu and Xuzhou area, and the area with AOD high value had gradually narrowed since 2014; the AOD of Zhejiang Province was significantly lower than the other areas, which was closely related to the high topography of Zhejiang Province; 3) the change of AOD had a good positive correlation with the temperature and relative humidity, but the correlation with wind speed was poor and complex, which may be affected by the uncertainty of wind direction. In summer, due to high temperature and humidity, most areas showed high AOD values, and the low temperature and air moisture content in winter caused low AOD. However, the contribution of solid particles to AOD was large in winter, so the change of AOD may reflect the air pollution in winter. The results can provide a reference for aerosol assessment, air quality attribution analysis and air quality improvement in the Yangtze River Delta in future.
2021, 39(12): 128-134.
doi: 10.13205/j.hjgc.202112019
Abstract:
The co-processing of municipal solid waste(MSW) with dry cement kiln has been paid attention all over the world because of its advantages such as high reaction temperature, low renovation cost, good comprehensive treatment performance and no secondary pollution. The removal characteristics of SO2 and HCl by cement clinker in simulated flue gas was investigated at 700~1000 ℃ in a fixed-bed experimental reactor. The adsorption mechanism of SO2 and HCl was discussed on the basis of physiochemical properties of original and spent cement clinker samples. The results indicated that the removal efficiency of SO2 by cement clinker increased rapidly as the reaction temperature increased from 700 ℃ to 1000 ℃, and the maximum unit adsorption capacity of SO2 reached 4.9 mg/g while only SO2 was present in simulated flue gas. The opposite was that the removal efficiency of HCl by cement clinker decreased as reaction temperature increased from 700 ℃ to 1000 ℃, and the corresponding unit adsorption capacity of HCl decreased from 8.40 mg/g to 4.8 mg/g while only HCl was present in the simulated flue gas. The initial adsorption rates of SO2 or HCl were determined by its concentration, and the adsorption rate of HCl was significantly larger than that of SO2. When SO2 and HCl were present in simulated flue gas, the removal performance of HCl by cement clinker decreased slightly, but existing HCl could significantly promote the SO2 removal performance and its adsorption reaction rate, and resulting in the unit adsorption capacity of SO2 at 700 ℃ and 1000 ℃ increased from 1.8 mg/g and 4.9 mg/g to 4.5 mg/g and 7.8 mg/g, respectively. The main reason of above results was the migration of chloride ions in spent cement clinker. These results provide a reference for the industrial application of a new co-processing technology using dry cement clinker to treat municipal solid waste incineration flue gas.
The co-processing of municipal solid waste(MSW) with dry cement kiln has been paid attention all over the world because of its advantages such as high reaction temperature, low renovation cost, good comprehensive treatment performance and no secondary pollution. The removal characteristics of SO2 and HCl by cement clinker in simulated flue gas was investigated at 700~1000 ℃ in a fixed-bed experimental reactor. The adsorption mechanism of SO2 and HCl was discussed on the basis of physiochemical properties of original and spent cement clinker samples. The results indicated that the removal efficiency of SO2 by cement clinker increased rapidly as the reaction temperature increased from 700 ℃ to 1000 ℃, and the maximum unit adsorption capacity of SO2 reached 4.9 mg/g while only SO2 was present in simulated flue gas. The opposite was that the removal efficiency of HCl by cement clinker decreased as reaction temperature increased from 700 ℃ to 1000 ℃, and the corresponding unit adsorption capacity of HCl decreased from 8.40 mg/g to 4.8 mg/g while only HCl was present in the simulated flue gas. The initial adsorption rates of SO2 or HCl were determined by its concentration, and the adsorption rate of HCl was significantly larger than that of SO2. When SO2 and HCl were present in simulated flue gas, the removal performance of HCl by cement clinker decreased slightly, but existing HCl could significantly promote the SO2 removal performance and its adsorption reaction rate, and resulting in the unit adsorption capacity of SO2 at 700 ℃ and 1000 ℃ increased from 1.8 mg/g and 4.9 mg/g to 4.5 mg/g and 7.8 mg/g, respectively. The main reason of above results was the migration of chloride ions in spent cement clinker. These results provide a reference for the industrial application of a new co-processing technology using dry cement clinker to treat municipal solid waste incineration flue gas.
2021, 39(12): 135-140.
doi: 10.13205/j.hjgc.202112020
Abstract:
Precisely predicting the concentration of PM2.5 and PM10 in air pollution can provide a scientific basis for the prevention and control of air pollution. However, in the absence of pollution source emission inventory and visibility data, the prediction accuracy of the existing PM2.5 and PM10 concentration prediction methods are not high. In addition, it is rarely reported that the current deep learning models have been applied successively to PM2.5 and PM10 concentration prediction research. Based on the historical air quality monitoring data and weather monitoring historical data in Guangzhou from June 1, 2015 to January 10, 2018, two traditional machine learning models(random forest model(RF) and XGBoost model) and two deep learning models(short-long-term memory network(LSTM) and gated recurrent unit network(GRU) were constructed respectively, to predict the daily average concentration of PM2.5 and PM10 in Guangzhou. The results showed that the four models could also well predict the daily average concentration of PM2.5 and PM10 in the absence of pollution source emission inventory and visibility data. According to the evaluation metrics, i.e., MSE, RMSE, MAPE, MAE, and R2, the PM2.5 and PM10 prediction effects of the four models were evaluated. The results indicated that the prediction effect of the deep GRU model was the best and the prediction results of the RF model were the worst. Compared with the commonly used RF model, XGBoost model, and LSTM model, the GRU model based on deep learning could better predict PM2.5 and PM10 concentration.
Precisely predicting the concentration of PM2.5 and PM10 in air pollution can provide a scientific basis for the prevention and control of air pollution. However, in the absence of pollution source emission inventory and visibility data, the prediction accuracy of the existing PM2.5 and PM10 concentration prediction methods are not high. In addition, it is rarely reported that the current deep learning models have been applied successively to PM2.5 and PM10 concentration prediction research. Based on the historical air quality monitoring data and weather monitoring historical data in Guangzhou from June 1, 2015 to January 10, 2018, two traditional machine learning models(random forest model(RF) and XGBoost model) and two deep learning models(short-long-term memory network(LSTM) and gated recurrent unit network(GRU) were constructed respectively, to predict the daily average concentration of PM2.5 and PM10 in Guangzhou. The results showed that the four models could also well predict the daily average concentration of PM2.5 and PM10 in the absence of pollution source emission inventory and visibility data. According to the evaluation metrics, i.e., MSE, RMSE, MAPE, MAE, and R2, the PM2.5 and PM10 prediction effects of the four models were evaluated. The results indicated that the prediction effect of the deep GRU model was the best and the prediction results of the RF model were the worst. Compared with the commonly used RF model, XGBoost model, and LSTM model, the GRU model based on deep learning could better predict PM2.5 and PM10 concentration.
2021, 39(12): 141-147.
doi: 10.13205/j.hjgc.202112021
Abstract:
Waste electrical and electronic equipment(WEEE, or electronic waste) possesses the dual properties with high resource value and environmental pollution, and its recycling and pollution control has become the research hotspot in the field of environmental engineering globally. On the basis of analyzing the achievements gained in the field of environmental management for WEEE in China and Japan, the research hereby put forward the typical challenges and problems which limit the sustainable development towards the industry in China. Finally, based on the experience of Japan's WEEE management and the principle of extended producer responsibility(EPR), it was suggested that the future environmental management for WEEE in China should be focused on optimizing the fund subsidy system, strengthening the management of WEEE outside the catalogue, increasing financial support for WEEE recycling companies, further improving the professional level of the third-party audit agencies, strengthening the effective connection between waste sorting and recycling and renewable resource recycling, and establishing robust information system for WEEE collecting and recycling. The findings of this research was expected to provide technical support for further improvement on the environmental management system for WEEE in China.
Waste electrical and electronic equipment(WEEE, or electronic waste) possesses the dual properties with high resource value and environmental pollution, and its recycling and pollution control has become the research hotspot in the field of environmental engineering globally. On the basis of analyzing the achievements gained in the field of environmental management for WEEE in China and Japan, the research hereby put forward the typical challenges and problems which limit the sustainable development towards the industry in China. Finally, based on the experience of Japan's WEEE management and the principle of extended producer responsibility(EPR), it was suggested that the future environmental management for WEEE in China should be focused on optimizing the fund subsidy system, strengthening the management of WEEE outside the catalogue, increasing financial support for WEEE recycling companies, further improving the professional level of the third-party audit agencies, strengthening the effective connection between waste sorting and recycling and renewable resource recycling, and establishing robust information system for WEEE collecting and recycling. The findings of this research was expected to provide technical support for further improvement on the environmental management system for WEEE in China.
2021, 39(12): 148-152.
doi: 10.13205/j.hjgc.202112022
Abstract:
Waste salt is the key hazardous waste in the pesticide industry, which is also the main bottleneck of the healthy development of the pesticide industry. The production status of pesticide waste salt was introduced, including the various kinds and large production volume, various production processes and types of pollutants, and great potential harm to the ecological environment and human body. At present, the pretreatment technologies to eliminate pollutants were pyrolysis carbonization, high temperature melting and organic matter oxidation. Based on the current situation of production and pretreatment, the utilization and disposal of waste salt including the production of chlor-alkali, soda ash, snow melting agent and cement grinding aid, as well as temporary storage in storehouse and landfill. In view of the problems existing in the utilization and disposal of waste salt, some suggestions on improving the utilization rate of waste salt and strengthen the safe disposal were put forward, which mainly included four aspects: 1) collect the waste salt after classification to avoid salt mixing and reduce the difficulty of pretreatment; 2) establish pollution control standards or technical specifications to prevent and control environmental risks in the process of waste salt utilization; 3) establish "point-to-point" directional utilization mode and centralized utilization mode in the industrial park, to improve the utilization rate of waste salt; 4) carry out environmental risk assessment of waste salt discharged into the sea to promote the return of salt to nature.
Waste salt is the key hazardous waste in the pesticide industry, which is also the main bottleneck of the healthy development of the pesticide industry. The production status of pesticide waste salt was introduced, including the various kinds and large production volume, various production processes and types of pollutants, and great potential harm to the ecological environment and human body. At present, the pretreatment technologies to eliminate pollutants were pyrolysis carbonization, high temperature melting and organic matter oxidation. Based on the current situation of production and pretreatment, the utilization and disposal of waste salt including the production of chlor-alkali, soda ash, snow melting agent and cement grinding aid, as well as temporary storage in storehouse and landfill. In view of the problems existing in the utilization and disposal of waste salt, some suggestions on improving the utilization rate of waste salt and strengthen the safe disposal were put forward, which mainly included four aspects: 1) collect the waste salt after classification to avoid salt mixing and reduce the difficulty of pretreatment; 2) establish pollution control standards or technical specifications to prevent and control environmental risks in the process of waste salt utilization; 3) establish "point-to-point" directional utilization mode and centralized utilization mode in the industrial park, to improve the utilization rate of waste salt; 4) carry out environmental risk assessment of waste salt discharged into the sea to promote the return of salt to nature.
2021, 39(12): 153-158.
doi: 10.13205/j.hjgc.202112023
Abstract:
Photocatalytic technology, as an emergingly efficient and sustainable technology, has broad application prospect in the environmental field. However, most photocatalytic materials will not generate electron-hole pairs in a short period of time without the energy supply of the external light source, and thus rapidly lose the catalytic activity. Photocatalytic memory materials have a unique ability, named as catalytic memory effect, to maintain catalytic performance under dark environments for overcoming the above challenges. This review article mainly outlined the basic principles of photocatalytic memory materials, classified the existing photocatalytic memory materials, summarized the application of photocatalytic memory materials in the environmental field, including the production of energy sources and the oxidation of refractory organics, the reduction of heavy metal and the inactivation of pathogenic microorganisms, and prospected for the future development of photocatalytic memory materials.
Photocatalytic technology, as an emergingly efficient and sustainable technology, has broad application prospect in the environmental field. However, most photocatalytic materials will not generate electron-hole pairs in a short period of time without the energy supply of the external light source, and thus rapidly lose the catalytic activity. Photocatalytic memory materials have a unique ability, named as catalytic memory effect, to maintain catalytic performance under dark environments for overcoming the above challenges. This review article mainly outlined the basic principles of photocatalytic memory materials, classified the existing photocatalytic memory materials, summarized the application of photocatalytic memory materials in the environmental field, including the production of energy sources and the oxidation of refractory organics, the reduction of heavy metal and the inactivation of pathogenic microorganisms, and prospected for the future development of photocatalytic memory materials.
2021, 39(12): 159-165,140.
doi: 10.13205/j.hjgc.202112024
Abstract:
The effect of slurry recirculation time(1 h/d, 6 h/d, 12 h/d and 24 h/d) on thermophilic((55±2) ℃) anaerobic digestion of kitchen waste for hydrogen production with high solid content(15%TS) was investigated in this study. The microbial community succession was studied in the condition of different slurry recirculation time. The results indicated that increasing the recirculation time of biogas slurry could improve the hydrogen production and alleviate VFAs accumulation. The maximum hydrogen production was obtained as 111.44 L at the recirculation time of 24 h/d. The concentration of VFAs was 28.34 g/L, 15.40% lower than that in the condition of 1 h/d. Increasing the recirculation time during anaerobic fermentation of kitchen waste could improve the pH of the acidification system, and the ammonia accumulation was not formed. In the experimental group with a shorter recirculation time(12 h/d), microbial community structural diversity decreased during the fermentation. At the phylum level, Firmicutes became the dominant bacteria(with a relative abundance of 49.2% to 89.5%). The experimental group maintained high microbial diversity at the condition of longer recirculation time, with the relative abundance of Firmicutes 27.8%, Chloroflexi 33.6%, Proteobacteria 13.0%, Euryarchaeota 12.3%. At the genus level, the group with longer recirculation time showed higher abundance of hydrogenogens, with the relative abundance of Clostridium 10.5% and Thermoanaerobacterium 3.2%. Extending slurry recirculation time could promote hydrogen production by metabolism of VFAs and glucose, and Proteiniphilum was the key microorganism for VFAs degradation. Redundancy analysis indicated that slurry recirculation time and biogas production were related to Firmicutes and Chloroflexi.
The effect of slurry recirculation time(1 h/d, 6 h/d, 12 h/d and 24 h/d) on thermophilic((55±2) ℃) anaerobic digestion of kitchen waste for hydrogen production with high solid content(15%TS) was investigated in this study. The microbial community succession was studied in the condition of different slurry recirculation time. The results indicated that increasing the recirculation time of biogas slurry could improve the hydrogen production and alleviate VFAs accumulation. The maximum hydrogen production was obtained as 111.44 L at the recirculation time of 24 h/d. The concentration of VFAs was 28.34 g/L, 15.40% lower than that in the condition of 1 h/d. Increasing the recirculation time during anaerobic fermentation of kitchen waste could improve the pH of the acidification system, and the ammonia accumulation was not formed. In the experimental group with a shorter recirculation time(12 h/d), microbial community structural diversity decreased during the fermentation. At the phylum level, Firmicutes became the dominant bacteria(with a relative abundance of 49.2% to 89.5%). The experimental group maintained high microbial diversity at the condition of longer recirculation time, with the relative abundance of Firmicutes 27.8%, Chloroflexi 33.6%, Proteobacteria 13.0%, Euryarchaeota 12.3%. At the genus level, the group with longer recirculation time showed higher abundance of hydrogenogens, with the relative abundance of Clostridium 10.5% and Thermoanaerobacterium 3.2%. Extending slurry recirculation time could promote hydrogen production by metabolism of VFAs and glucose, and Proteiniphilum was the key microorganism for VFAs degradation. Redundancy analysis indicated that slurry recirculation time and biogas production were related to Firmicutes and Chloroflexi.
2021, 39(12): 166-171,205.
doi: 10.13205/j.hjgc.202112025
Abstract:
The three-phase separation residue from restaurant food waste treatment plant is a kind of perishable organic waste of acidic and offensive odor, high moisture content, and sludge-like appearance. Housefly larvae(maggots) can efficiently and quickly transformed restaurant food waste into high added-value animal protein(maggots) and high-quality organic fertilizer, assisted by mechanized operation. The pilot-scale production line of fly maggot treatment consisted of feeding, fly maggot culture, maggot-medium separation, and deodorization/dehumidification systems. The designed treatment capacity and processing time of the line was 500 kg and about 4 days for each batch, respectively. After bio-conversion, restaurant food waste became relatively dry, fluffy and odorless organic fertilizer. The conversion rate of the waste was 23.6% for yielding organic fertilizer and 17.4% for maggots. According to the current market assessment, processing 1 ton of raw restaurant food waste entering the restaurant food waste treatment plant could produce RMB 280~320 of value-added products. Therefore, this technology was of great application prospect.
The three-phase separation residue from restaurant food waste treatment plant is a kind of perishable organic waste of acidic and offensive odor, high moisture content, and sludge-like appearance. Housefly larvae(maggots) can efficiently and quickly transformed restaurant food waste into high added-value animal protein(maggots) and high-quality organic fertilizer, assisted by mechanized operation. The pilot-scale production line of fly maggot treatment consisted of feeding, fly maggot culture, maggot-medium separation, and deodorization/dehumidification systems. The designed treatment capacity and processing time of the line was 500 kg and about 4 days for each batch, respectively. After bio-conversion, restaurant food waste became relatively dry, fluffy and odorless organic fertilizer. The conversion rate of the waste was 23.6% for yielding organic fertilizer and 17.4% for maggots. According to the current market assessment, processing 1 ton of raw restaurant food waste entering the restaurant food waste treatment plant could produce RMB 280~320 of value-added products. Therefore, this technology was of great application prospect.
2021, 39(12): 172-178.
doi: 10.13205/j.hjgc.202112026
Abstract:
The pyrolysis char was produced from typical combustible components in MSW, and combustion behavior of which was evaluated based on both combustion activity and cleanliness. Biomass chars, prepared from raw materials such as pine wood, hardboard and orange peel chars, have relatively richer K/Ca content and less ordered carbon structure, leading to higher combustion activity and stability. The yields, texture structure and carbon structure of fossil fuel chars, such as PVC, tyre and chemical fiber fabrics chars, varied. Among which, the tyre char has a mesoporous structure and higher content of S and Zn. The NOx concentration in the flue gas from biomass char combustion was relatively higher(140.7~385.5 mg/m3), while SO2 concentration(1889.8 mg/m3) in the flue gas, and Zn content(198167 mg/kg) in the ash from tyre char combustion were relatively higher. Special attention should be paid on these pollutants in real practice.
The pyrolysis char was produced from typical combustible components in MSW, and combustion behavior of which was evaluated based on both combustion activity and cleanliness. Biomass chars, prepared from raw materials such as pine wood, hardboard and orange peel chars, have relatively richer K/Ca content and less ordered carbon structure, leading to higher combustion activity and stability. The yields, texture structure and carbon structure of fossil fuel chars, such as PVC, tyre and chemical fiber fabrics chars, varied. Among which, the tyre char has a mesoporous structure and higher content of S and Zn. The NOx concentration in the flue gas from biomass char combustion was relatively higher(140.7~385.5 mg/m3), while SO2 concentration(1889.8 mg/m3) in the flue gas, and Zn content(198167 mg/kg) in the ash from tyre char combustion were relatively higher. Special attention should be paid on these pollutants in real practice.
2021, 39(12): 179-187.
doi: 10.13205/j.hjgc.202112027
Abstract:
A stimulated experiment was carried out to investigate the promotion of anaerobic digestion of kitchen waste by biochar at high organic loads(30 g VS/L). The results indicated that the cumulative methane production was increased by 101.7% to 312.40 mL CH4/g VS after 20 d at the optimum addition of alkaline porous biochar(1 g/g VS), while the lag phase for methane production was reduced by 62% as compared to the control group. Besides, the addition of biochar reduced the volatile fatty acid(VFA) content by 1151.28 mg/L at the most severe acidifying stage. Mechanism exploration disclosed that the porous structure of biochar exerted vital influence on the decomposition of VFA, and alkalinity and nutrients also played an important role in the VFA degradation. The results of high-throughput sequencing showed that the relative abundance of Methanothrix, Bacteroidales and Clostridiales were increased from 26.12%, 43.08% and 9.95% to 46.05%, 56.25% and 12.20%, respectively. The underlying mechanism for biochar affecting the digestion were providing reaction sites for microorganisms, enhancing electron transfer among microorganisms, and accelerating the respiration rate of the microorganisms.
A stimulated experiment was carried out to investigate the promotion of anaerobic digestion of kitchen waste by biochar at high organic loads(30 g VS/L). The results indicated that the cumulative methane production was increased by 101.7% to 312.40 mL CH4/g VS after 20 d at the optimum addition of alkaline porous biochar(1 g/g VS), while the lag phase for methane production was reduced by 62% as compared to the control group. Besides, the addition of biochar reduced the volatile fatty acid(VFA) content by 1151.28 mg/L at the most severe acidifying stage. Mechanism exploration disclosed that the porous structure of biochar exerted vital influence on the decomposition of VFA, and alkalinity and nutrients also played an important role in the VFA degradation. The results of high-throughput sequencing showed that the relative abundance of Methanothrix, Bacteroidales and Clostridiales were increased from 26.12%, 43.08% and 9.95% to 46.05%, 56.25% and 12.20%, respectively. The underlying mechanism for biochar affecting the digestion were providing reaction sites for microorganisms, enhancing electron transfer among microorganisms, and accelerating the respiration rate of the microorganisms.
2021, 39(12): 188-192.
doi: 10.13205/j.hjgc.202112028
Abstract:
In this study, the effects of lactic acid fermentation broth and ultrapure water on removal of chlorine from fly ash were compared. The results suggested that 59.3% of water-insoluble chlorine in fly ash could be removed by lactic acid fermentation broth, and the ratio of fly ash entering kiln increased from 0.57% to 1.74% after treatment. Experimental results also demonstrated that the heavy metal content of fly ash after leaching by lactic acid fermentation broth was enriched. However, the heavy metal content in the fly ash residue was still lower than the limit value specified in China's national standard HJ 662—2013. Overall, replacing the water leaching with lactic acid fermentation broth leaching could be effective for the fly ash pretreatment.
In this study, the effects of lactic acid fermentation broth and ultrapure water on removal of chlorine from fly ash were compared. The results suggested that 59.3% of water-insoluble chlorine in fly ash could be removed by lactic acid fermentation broth, and the ratio of fly ash entering kiln increased from 0.57% to 1.74% after treatment. Experimental results also demonstrated that the heavy metal content of fly ash after leaching by lactic acid fermentation broth was enriched. However, the heavy metal content in the fly ash residue was still lower than the limit value specified in China's national standard HJ 662—2013. Overall, replacing the water leaching with lactic acid fermentation broth leaching could be effective for the fly ash pretreatment.
2021, 39(12): 193-198,233.
doi: 10.13205/j.hjgc.202112029
Abstract:
With the random accumulation or landfill of construction waste in the process of urbanization, a large number of informal construction waste dumps appeared. Garbage Besieged City becomes a prominent problem of the current society in China. Therefore, it is urgent to study the present situation and countermeasures of spatial distribution of construction waste for the optimization of spatial distribution of construction waste in China. This paper took Changping District of Beijing as an example, identified the number, geographical location, area, distance from residential areas and rivers and other information of informal construction waste dump sites based on Google earth and GIS software, and then obtained the general information of garbage distribution. The spatial layout characteristics of these information in terms of point space, distribution and elevation were analyzed, so as to clarify the layout problem of informal garbage dump, and then the problems in irregular garbage dump layout was clarified, and suggestions were also put forward, so as to improve the management capacity of construction waste and solve the problem of Garbage Besieged City.
With the random accumulation or landfill of construction waste in the process of urbanization, a large number of informal construction waste dumps appeared. Garbage Besieged City becomes a prominent problem of the current society in China. Therefore, it is urgent to study the present situation and countermeasures of spatial distribution of construction waste for the optimization of spatial distribution of construction waste in China. This paper took Changping District of Beijing as an example, identified the number, geographical location, area, distance from residential areas and rivers and other information of informal construction waste dump sites based on Google earth and GIS software, and then obtained the general information of garbage distribution. The spatial layout characteristics of these information in terms of point space, distribution and elevation were analyzed, so as to clarify the layout problem of informal garbage dump, and then the problems in irregular garbage dump layout was clarified, and suggestions were also put forward, so as to improve the management capacity of construction waste and solve the problem of Garbage Besieged City.
2021, 39(12): 199-205.
doi: 10.13205/j.hjgc.202112030
Abstract:
The process of extraction of iron and aluminum from red mud by using oxalic acid leaching was investigated systematically. The effect of oxalic acid addition, leaching time, leaching temperature and liquid to solid ratio on the leaching efficiency were investigated respectively, and the response surface method was used to the optimize the preparation process based on the single-factor experiment results. The Fe(Ⅲ) oxalate in the leaching solution was reduced to Fe(Ⅱ) oxalate by using sunlight irradiation. The experiment results showed that the regression equation model was of great significant. The optimized processing conditions for leaching rate were as follows: the oxalic acid concentration of 0.30 g/mL, the liquid-solid ratio of 14∶1, reaction temperature of 95 ℃, reaction time of 150 min. Under the optimal conditions, the leaching rates of iron and aluminum were up to 87.76% and 74.60%, respectively. The total iron concentration decreased from 1.152 g/L to 0.173 g/L in the extracted solution, and more than 85% Fe(Ⅲ) oxalate was transformed into the Fe(Ⅱ) oxalate crystallite within 420 min by using sunlight irradiation. The aluminum and oxalic acid in the filtrate could be recovered by means of adjusting pH value, filtration, and evaporation crystallization successively. The study provides new technical routine for the recovery of iron and aluminum from red mud.
The process of extraction of iron and aluminum from red mud by using oxalic acid leaching was investigated systematically. The effect of oxalic acid addition, leaching time, leaching temperature and liquid to solid ratio on the leaching efficiency were investigated respectively, and the response surface method was used to the optimize the preparation process based on the single-factor experiment results. The Fe(Ⅲ) oxalate in the leaching solution was reduced to Fe(Ⅱ) oxalate by using sunlight irradiation. The experiment results showed that the regression equation model was of great significant. The optimized processing conditions for leaching rate were as follows: the oxalic acid concentration of 0.30 g/mL, the liquid-solid ratio of 14∶1, reaction temperature of 95 ℃, reaction time of 150 min. Under the optimal conditions, the leaching rates of iron and aluminum were up to 87.76% and 74.60%, respectively. The total iron concentration decreased from 1.152 g/L to 0.173 g/L in the extracted solution, and more than 85% Fe(Ⅲ) oxalate was transformed into the Fe(Ⅱ) oxalate crystallite within 420 min by using sunlight irradiation. The aluminum and oxalic acid in the filtrate could be recovered by means of adjusting pH value, filtration, and evaporation crystallization successively. The study provides new technical routine for the recovery of iron and aluminum from red mud.
2021, 39(12): 206-211,219.
doi: 10.13205/j.hjgc.202112031
Abstract:
In order to understand the soil Cr(Ⅵ) pollution and distribution characteristics in the sludge and soil of tanning site, soil and sludge samples of three typical site in China were selected to analyze the soil Cr(Ⅵ) pollution characteristics of tanning industry. The results showed that the highest content of soil Cr(Ⅵ) in the investigated type Ⅰ tanning enterprise's site was 48 mg/kg, which exceeded the screening value of the standard of soil pollution risk control for construction land(GB 36600—2018). There was pollution and environmental risk in Cr(Ⅵ). The investigated type Ⅱ tanning enterprise's site had complete environmental protection facilities, and the content of soil Cr(Ⅵ) was generally low, lower than the screening value of GB 36600—2018, with a lower environmental risk. The total chromium content of sludge in the temporary storage room of hazardous waste in type Ⅱ tanning enterprises' s site was as high as 85377 mg/kg, and the highest Cr(Ⅵ) content was 1455 mg/kg. The total chromium content of soil mixture in type Ⅲ tanning enterprise's site investigated ranged from 1564 to 28000 mg/kg, and the highest Cr(Ⅵ) content was 250 mg/kg. Compared with type Ⅰ and type Ⅱ tanning sites, it was seriously polluted. In general, Cr(Ⅲ) was the main form of soil chromium in tanning sites, and Cr(Ⅵ) accounted for less than 1%.
In order to understand the soil Cr(Ⅵ) pollution and distribution characteristics in the sludge and soil of tanning site, soil and sludge samples of three typical site in China were selected to analyze the soil Cr(Ⅵ) pollution characteristics of tanning industry. The results showed that the highest content of soil Cr(Ⅵ) in the investigated type Ⅰ tanning enterprise's site was 48 mg/kg, which exceeded the screening value of the standard of soil pollution risk control for construction land(GB 36600—2018). There was pollution and environmental risk in Cr(Ⅵ). The investigated type Ⅱ tanning enterprise's site had complete environmental protection facilities, and the content of soil Cr(Ⅵ) was generally low, lower than the screening value of GB 36600—2018, with a lower environmental risk. The total chromium content of sludge in the temporary storage room of hazardous waste in type Ⅱ tanning enterprises' s site was as high as 85377 mg/kg, and the highest Cr(Ⅵ) content was 1455 mg/kg. The total chromium content of soil mixture in type Ⅲ tanning enterprise's site investigated ranged from 1564 to 28000 mg/kg, and the highest Cr(Ⅵ) content was 250 mg/kg. Compared with type Ⅰ and type Ⅱ tanning sites, it was seriously polluted. In general, Cr(Ⅲ) was the main form of soil chromium in tanning sites, and Cr(Ⅵ) accounted for less than 1%.
2021, 39(12): 212-219.
doi: 10.13205/j.hjgc.202112032
Abstract:
A method that the pouring soil into the plasma of dielectric barrier discharge(DBD) to efficiently degrade atrazine in the soil was studied. The effects of soil characteristics and plasma generation parameters on atrazine degradation were investigated and the degradation intermediates were detected and analyzed. The experiment results showed that increasing voltage and frequency could improve the degradation efficiency of atrazine and reduce the energy efficiency. The increase of initial concentration would lead to the decrease of degradation efficiency and the increase of energy efficiency. The degradation efficiency and energy efficiency were decreased when soil particle size increased or pH decreased. As water content increased, degradation efficiency and energy efficiency first increased and then decreased. Under the conditions of peak-peak 36 kV, 200 Hz, and pH of 7.03, the degradation efficiency and energy efficiency of 10 mg/kg polluted dry soil with particle size of 60~80 were 70.95% and 0.014 mg/kJ after discharge treatment for 50 s. Through liquid chromatography-mass spectrometry, the intermediate products were tested to be atrazine-like substances such as dealkylation, dechlorination and ketone or aldehyde without any oligomer. As non-thermal plasma was generated around the soil particles, ozone and the short-lived active species, such as ·OH, jointly participated in the pollutant degradation process, resulting in enhanced reactor degradation effect.
A method that the pouring soil into the plasma of dielectric barrier discharge(DBD) to efficiently degrade atrazine in the soil was studied. The effects of soil characteristics and plasma generation parameters on atrazine degradation were investigated and the degradation intermediates were detected and analyzed. The experiment results showed that increasing voltage and frequency could improve the degradation efficiency of atrazine and reduce the energy efficiency. The increase of initial concentration would lead to the decrease of degradation efficiency and the increase of energy efficiency. The degradation efficiency and energy efficiency were decreased when soil particle size increased or pH decreased. As water content increased, degradation efficiency and energy efficiency first increased and then decreased. Under the conditions of peak-peak 36 kV, 200 Hz, and pH of 7.03, the degradation efficiency and energy efficiency of 10 mg/kg polluted dry soil with particle size of 60~80 were 70.95% and 0.014 mg/kJ after discharge treatment for 50 s. Through liquid chromatography-mass spectrometry, the intermediate products were tested to be atrazine-like substances such as dealkylation, dechlorination and ketone or aldehyde without any oligomer. As non-thermal plasma was generated around the soil particles, ozone and the short-lived active species, such as ·OH, jointly participated in the pollutant degradation process, resulting in enhanced reactor degradation effect.
2021, 39(12): 220-226.
doi: 10.13205/j.hjgc.202112033
Abstract:
For the purpose of studying the in-situ plant restoration effect of ecological restoration on lead/zinc mine tailings pond, the comprehensive treatment demonstration project of tailing reservoir in Yangshuo lead zinc mine was chosen as the study object, to investigate and analyze the tails physical-chemical properties, heavy metals and enzyme activity in three reclamation years, and vegetation restoration and the growth of new plants were observed on-site for 3 consecutive years(2018—2020). The results showed that the artificially planted Miscanthus sinensis and Pueraria phaseoloides, two tolerant plants in the tailings bank, could stabilize the heavy metals in the tailings. The newly added species of vegetation in the reservoir area increased year by year, mainly Fabaceae and Asteraceae; catalase, urease and the phosphatase activity first increased and then decreased, the invertase activity increased significantly; the fertility and fertilizer retention capacity of tailings were improved and the total nitrogen content of tailings increased from 1.14 g/kg to 2.19 g/kg. The organic carbon content increased from 9.50 g/kg to 21.01 g/kg. This showed that in the ecological restoration of mine wasteland with similar natural conditions, the target plants from Pueraria and Artemisia should be selected; vegetation restoration would accelerate the secondary succession of plant communities in the tailings reservoir area; the artificial vegetation restoration of the lead-zinc mine tailings reservoir could accelerate the evolution of the tailings substrate, promote the restoration of ecosystem and maintain its well-ordered ecological cycle.
For the purpose of studying the in-situ plant restoration effect of ecological restoration on lead/zinc mine tailings pond, the comprehensive treatment demonstration project of tailing reservoir in Yangshuo lead zinc mine was chosen as the study object, to investigate and analyze the tails physical-chemical properties, heavy metals and enzyme activity in three reclamation years, and vegetation restoration and the growth of new plants were observed on-site for 3 consecutive years(2018—2020). The results showed that the artificially planted Miscanthus sinensis and Pueraria phaseoloides, two tolerant plants in the tailings bank, could stabilize the heavy metals in the tailings. The newly added species of vegetation in the reservoir area increased year by year, mainly Fabaceae and Asteraceae; catalase, urease and the phosphatase activity first increased and then decreased, the invertase activity increased significantly; the fertility and fertilizer retention capacity of tailings were improved and the total nitrogen content of tailings increased from 1.14 g/kg to 2.19 g/kg. The organic carbon content increased from 9.50 g/kg to 21.01 g/kg. This showed that in the ecological restoration of mine wasteland with similar natural conditions, the target plants from Pueraria and Artemisia should be selected; vegetation restoration would accelerate the secondary succession of plant communities in the tailings reservoir area; the artificial vegetation restoration of the lead-zinc mine tailings reservoir could accelerate the evolution of the tailings substrate, promote the restoration of ecosystem and maintain its well-ordered ecological cycle.
2021, 39(12): 227-233.
doi: 10.13205/j.hjgc.202112034
Abstract:
Most radionuclides have characteristics of strong radioactivity, long half-life, and high toxicity. After entering the soil, they are prone to a series of reactions such as migration and morphological transformation under the influence of environmental changes. The nuclides entering the soil could be passively absorbed by plants and ultimately harmed through the food chain to human health. Plant rhizosphere is the only way for radionuclides to migrate from soil to plant. Soil colloids are the main constituents of rhizosphere microregions and important carriers for the adsorption of radionuclides. The root exudate is the most important difference between the rhizosphere and the soil. And pH is an important physical and chemical condition for the occurrence and migration of radionuclides. Root microorganisms are regulators in the rhizosphere microregions. This article summarized the research progress of radionuclides migration in rhizosphere microregions in recent five years, from soil colloids, root exudates, pH, root microorganisms, comprehensively expounded the environmental impact of nuclide migration in the rhizosphere microregions, and put forward the prospects for the related researches in the future.
Most radionuclides have characteristics of strong radioactivity, long half-life, and high toxicity. After entering the soil, they are prone to a series of reactions such as migration and morphological transformation under the influence of environmental changes. The nuclides entering the soil could be passively absorbed by plants and ultimately harmed through the food chain to human health. Plant rhizosphere is the only way for radionuclides to migrate from soil to plant. Soil colloids are the main constituents of rhizosphere microregions and important carriers for the adsorption of radionuclides. The root exudate is the most important difference between the rhizosphere and the soil. And pH is an important physical and chemical condition for the occurrence and migration of radionuclides. Root microorganisms are regulators in the rhizosphere microregions. This article summarized the research progress of radionuclides migration in rhizosphere microregions in recent five years, from soil colloids, root exudates, pH, root microorganisms, comprehensively expounded the environmental impact of nuclide migration in the rhizosphere microregions, and put forward the prospects for the related researches in the future.
2021, 39(12): 234-242.
doi: 10.13205/j.hjgc.202112035
Abstract:
The changes of chromium speciation, microbial communities and enzyme activities in red soil treatment system planted with Leersia hexandra Swartz with or without 10 g/kg humic acid were studied. The results showed that residual fraction was dominant in the substrate after humic acid added. The residual fraction was dominant in the stem and leaves while the hydrochloric acid fraction was dominant in the root. The number of bacteria, fungi and actinomycete could be significantly promoted by humic acid, and the maximum number of the three microbial groups was 6.76×107, 4.48×107, 7.71×107 CFU/g. The analysis of enzyme activities showed that humic acid increased the activity of invertase and alkaline phosphatase and decreased the activity of catalase and polyphenol oxidase. The correlation analysis showed that the activities of polyphenol oxidase and catalase were negatively correlated with the number of bacteria and the concentration of humic acid. The number of bacteria, fungi and actinomycetes was positively correlated with the concentration of humic acid. The number of bacteria, fungi and actinomyces were positively correlated with the content of chromium in the substrate residual fraction. A negative correlation existed between invertase and the content of chromium fractions in substrate and in Leersia hexandra Swartz. There was a positive correlation between the activity of polyphenol oxidase and most chromium fractions in Leersia hexandra Swartz.
The changes of chromium speciation, microbial communities and enzyme activities in red soil treatment system planted with Leersia hexandra Swartz with or without 10 g/kg humic acid were studied. The results showed that residual fraction was dominant in the substrate after humic acid added. The residual fraction was dominant in the stem and leaves while the hydrochloric acid fraction was dominant in the root. The number of bacteria, fungi and actinomycete could be significantly promoted by humic acid, and the maximum number of the three microbial groups was 6.76×107, 4.48×107, 7.71×107 CFU/g. The analysis of enzyme activities showed that humic acid increased the activity of invertase and alkaline phosphatase and decreased the activity of catalase and polyphenol oxidase. The correlation analysis showed that the activities of polyphenol oxidase and catalase were negatively correlated with the number of bacteria and the concentration of humic acid. The number of bacteria, fungi and actinomycetes was positively correlated with the concentration of humic acid. The number of bacteria, fungi and actinomyces were positively correlated with the content of chromium in the substrate residual fraction. A negative correlation existed between invertase and the content of chromium fractions in substrate and in Leersia hexandra Swartz. There was a positive correlation between the activity of polyphenol oxidase and most chromium fractions in Leersia hexandra Swartz.
