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2021 Vol. 39, No. 6
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2021, 39(6): 1-5,26.
doi: 10.13205/j.hjgc.202106001
Abstract:
In order to reduce the risk of ecological environment when the reclaimed water from a sewage plant is reused in the urban landscape water body, this paper took the ecological restoration section of a sewage plant in Ningbo as the research object, used the ecological integration technology to purify and repair the reclaimed water, and studied its conventional water quality index, comprehensive biological toxicity of water body and characteristics of river benthos community impact. The results showed that the ecological restoration measures had obvious effect on the stability of reclaimed water quality; the main water quality indicators remained stable and met the water quality requirements of the functional area; the toxicity of reclaimed water quality was reduced; the species richness and biological density of benthos in the river were also increased significantly, which effectively reduced the ecological risks from the replenishment of reclaimed water, had a significant impact on the flow and ecological safety of urban river water.
In order to reduce the risk of ecological environment when the reclaimed water from a sewage plant is reused in the urban landscape water body, this paper took the ecological restoration section of a sewage plant in Ningbo as the research object, used the ecological integration technology to purify and repair the reclaimed water, and studied its conventional water quality index, comprehensive biological toxicity of water body and characteristics of river benthos community impact. The results showed that the ecological restoration measures had obvious effect on the stability of reclaimed water quality; the main water quality indicators remained stable and met the water quality requirements of the functional area; the toxicity of reclaimed water quality was reduced; the species richness and biological density of benthos in the river were also increased significantly, which effectively reduced the ecological risks from the replenishment of reclaimed water, had a significant impact on the flow and ecological safety of urban river water.
2021, 39(6): 6-14.
doi: 10.13205/j.hjgc.202106002
Abstract:
Graphite oxide/polyvinyl alcohol composite electrospun fibrous membrane was prepared by using electrospinning technology, and the carbon nanomaterial graphite oxide could be in situ immobilized in the polyvinyl alcohol fibers. The composite fibrous membrane was used as a solar photo-thermal conversion material for desalination treatment of simulated seawater. The results showed that the composite fibrous membrane was an excellent photo-thermal conversion material. It was extremely hydrophilic, also had a wide spectral absorption range and high photo-absorption rate at wet state. The composite fibrous membranes produced under the conditions of spinning voltage of 15 kV, electrode plate spacing of 15 cm, and graphite oxide mass concentration of 3%(vs. polyvinyl alcohol) had the best photo-thermal conversion properties. Under the irradiation of 1 sunshine unit(1 kW/m2), the surface of membrane could be rapidly heated to about 50℃. The water evaporation rate could reach 1.09 kg/(m2·h), and the photo-thermal conversion efficiency was 71.9%. The composite fibrous membrane could achieve more than 99.9% of desalination efficiency for simulated seawater with different NaCl concentrations. Moreover, the composite fibrous membrane has good stability and reusability, and can be well applied in the field of ordinary seawater desalination.
Graphite oxide/polyvinyl alcohol composite electrospun fibrous membrane was prepared by using electrospinning technology, and the carbon nanomaterial graphite oxide could be in situ immobilized in the polyvinyl alcohol fibers. The composite fibrous membrane was used as a solar photo-thermal conversion material for desalination treatment of simulated seawater. The results showed that the composite fibrous membrane was an excellent photo-thermal conversion material. It was extremely hydrophilic, also had a wide spectral absorption range and high photo-absorption rate at wet state. The composite fibrous membranes produced under the conditions of spinning voltage of 15 kV, electrode plate spacing of 15 cm, and graphite oxide mass concentration of 3%(vs. polyvinyl alcohol) had the best photo-thermal conversion properties. Under the irradiation of 1 sunshine unit(1 kW/m2), the surface of membrane could be rapidly heated to about 50℃. The water evaporation rate could reach 1.09 kg/(m2·h), and the photo-thermal conversion efficiency was 71.9%. The composite fibrous membrane could achieve more than 99.9% of desalination efficiency for simulated seawater with different NaCl concentrations. Moreover, the composite fibrous membrane has good stability and reusability, and can be well applied in the field of ordinary seawater desalination.
2021, 39(6): 15-20.
doi: 10.13205/j.hjgc.202106003
Abstract:
The dewaterability of excess sludge from wastewater treatment facilities in rural areas was investigated, and single factor and comprehensive experimental methods were used to optimize the condition of the sludge with single and compound chemicals. Meanwhile, the stirring parameters were further optimized by applying response surface methods. The experimental results showed the variation dewaterability of the excess sludge between different rural wastewater treatment facilities was quite different. Both single and compound conditioners could significantly reduce the capillary suction time(CST) of sludge and improve the sludge dewatering. The optimization results showed that the suitable stirring speed and stirring time could further reduce the CST of sludge. The best combination was polyaluminium chloride(PAC) and polyacrylamide(PAM), when the first stirring speed and time were 500 r/min and 0.5 min, and the second stirring speed and time were 150 r/min and 10 min, sludge CST value reached 10.1. Additionally, the total cost of the conditioning was equal to RMB 10.69/ton wet sludge with moisture content of 98%.
The dewaterability of excess sludge from wastewater treatment facilities in rural areas was investigated, and single factor and comprehensive experimental methods were used to optimize the condition of the sludge with single and compound chemicals. Meanwhile, the stirring parameters were further optimized by applying response surface methods. The experimental results showed the variation dewaterability of the excess sludge between different rural wastewater treatment facilities was quite different. Both single and compound conditioners could significantly reduce the capillary suction time(CST) of sludge and improve the sludge dewatering. The optimization results showed that the suitable stirring speed and stirring time could further reduce the CST of sludge. The best combination was polyaluminium chloride(PAC) and polyacrylamide(PAM), when the first stirring speed and time were 500 r/min and 0.5 min, and the second stirring speed and time were 150 r/min and 10 min, sludge CST value reached 10.1. Additionally, the total cost of the conditioning was equal to RMB 10.69/ton wet sludge with moisture content of 98%.
2021, 39(6): 21-26.
doi: 10.13205/j.hjgc.202106004
Abstract:
Based on the qualitative analysis of relationship of recharge and discharge between surface water and groundwater in Maozhou River Basin, we established SWAT and SWAT-LUD models to simulate the circulation and transformation process of watershed water, quantified the interactive volume between surface water and ground water, and estimated the pollutant contribution. The results showed that the volume of groundwater recharge to surface water was 1.6×108 m3 in 2017, with the amount of NH3-N、TP and COD at 0.9×104, 0.2×104 and 1.7×104 t, respectively, and approximately contributed 3% of the total river pollutants; the volume of surface water recharge to groundwater was 1.0×106 m3, with the amount of NH3-N, TP and COD at 11 t, 1.1 t and 510 t, respectively, and contributed 2% of the total pollutants of groundwater recharge surface water; the amount of groundwater recharged by river water infiltration in flood area was 6.7×106 m3. On the basis of above research, we suggested to adopt engineering measures, such as sediment dredging, construction of permeable reaction wall in interactive zone, building sluice on river estuary, watershed water environmental early-warning and monitoring in interactive zone, to implement joint prevention of surface water and groundwater pollution in Maozhou River Basin.
Based on the qualitative analysis of relationship of recharge and discharge between surface water and groundwater in Maozhou River Basin, we established SWAT and SWAT-LUD models to simulate the circulation and transformation process of watershed water, quantified the interactive volume between surface water and ground water, and estimated the pollutant contribution. The results showed that the volume of groundwater recharge to surface water was 1.6×108 m3 in 2017, with the amount of NH3-N、TP and COD at 0.9×104, 0.2×104 and 1.7×104 t, respectively, and approximately contributed 3% of the total river pollutants; the volume of surface water recharge to groundwater was 1.0×106 m3, with the amount of NH3-N, TP and COD at 11 t, 1.1 t and 510 t, respectively, and contributed 2% of the total pollutants of groundwater recharge surface water; the amount of groundwater recharged by river water infiltration in flood area was 6.7×106 m3. On the basis of above research, we suggested to adopt engineering measures, such as sediment dredging, construction of permeable reaction wall in interactive zone, building sluice on river estuary, watershed water environmental early-warning and monitoring in interactive zone, to implement joint prevention of surface water and groundwater pollution in Maozhou River Basin.
2021, 39(6): 27-33.
doi: 10.13205/j.hjgc.202106005
Abstract:
In order to evaluate the water purification capacities of household activated carbon drinking water purifiers and the behavioral characteristics of antibiotic resistance genes(ARGs), six kinds of household activated carbon water purifiers with different filter structures were purchased in this study. The dynamic changes of conventional water quality indicators and ARGs were tracked for 80 days. The research results showed that activated carbon drinking water purifiers could effectively remove residual chlorine for a long period of time. The removal effect of organic matter deteriorated with time. The physical properties of activated carbon had a great impact on water purification performance. Large specific surface area helped to remove organics. Five ARGs were quantitatively analyzed by qPCR, and the absolute abundances of sul1 and tetA were the highest. The absolute abundances of ARGs in the filtered water gradually increased with time, and reached a high level in 48~80 days in general. Sintered activated carbon with rigid pores and gradually-tight filter structure could play a certain control effect on ARGs. Organic matter and intI1 in water played an important role in the proliferation and transmission of ARGs.
In order to evaluate the water purification capacities of household activated carbon drinking water purifiers and the behavioral characteristics of antibiotic resistance genes(ARGs), six kinds of household activated carbon water purifiers with different filter structures were purchased in this study. The dynamic changes of conventional water quality indicators and ARGs were tracked for 80 days. The research results showed that activated carbon drinking water purifiers could effectively remove residual chlorine for a long period of time. The removal effect of organic matter deteriorated with time. The physical properties of activated carbon had a great impact on water purification performance. Large specific surface area helped to remove organics. Five ARGs were quantitatively analyzed by qPCR, and the absolute abundances of sul1 and tetA were the highest. The absolute abundances of ARGs in the filtered water gradually increased with time, and reached a high level in 48~80 days in general. Sintered activated carbon with rigid pores and gradually-tight filter structure could play a certain control effect on ARGs. Organic matter and intI1 in water played an important role in the proliferation and transmission of ARGs.
2021, 39(6): 34-41,121.
doi: 10.13205/j.hjgc.202106006
Abstract:
Aeration tank is an important unit of activated sludge process, and also the unit with the largest energy consumption, which provides necessary oxygen for the treatment of pollutants by aerobic biochemical process. The study of aeration control is of great significance for the improvement of effluent water quality and saving of operation cost. With the development of wastewater treatment technology, the control of aeration is becoming more and more refined. The traditional aeration control takes feedback and fine-tuning as the core, the new aeration control system includes precise aeration control with the core of model calculation, and intelligent aeration control with the core of rule-based reasoning. In this paper, the operation regulation and implementation method of the control system were summarized, then, the existing aeration control system was evaluated, and some optimization suggestions were put forward from the aspects of control parameters, control modes, hardware and software. Finally, the prospect of aeration control system was prospected.
Aeration tank is an important unit of activated sludge process, and also the unit with the largest energy consumption, which provides necessary oxygen for the treatment of pollutants by aerobic biochemical process. The study of aeration control is of great significance for the improvement of effluent water quality and saving of operation cost. With the development of wastewater treatment technology, the control of aeration is becoming more and more refined. The traditional aeration control takes feedback and fine-tuning as the core, the new aeration control system includes precise aeration control with the core of model calculation, and intelligent aeration control with the core of rule-based reasoning. In this paper, the operation regulation and implementation method of the control system were summarized, then, the existing aeration control system was evaluated, and some optimization suggestions were put forward from the aspects of control parameters, control modes, hardware and software. Finally, the prospect of aeration control system was prospected.
2021, 39(6): 42-48,166.
doi: 10.13205/j.hjgc.202106007
Abstract:
Artificial wastewater was used in this study, and parameters of the algae-bacteria immobilized pellets and the growth of microorganism were optimized based on treatment efficiency of livestock wastewater. The orthogonal experiment was designed for optimization of immobilized pellet strength, the growth of microorganism and removal efficiency, using multi-index full probability analysis and SPSS software analysis. The results were concluded as a set of parameters including the concentration of sodium alginate(SA) and calcium chloride(CaCl2) and the immobilization time. Then, the response surface experiment designed by analysis software Design-Expert 10 were carried out to further optimize these parameters. The results showed that the optimized parameters of orthogonal experiment were SA concentration of 3%, the CaCl2 concentration of 1%, and the immobilization time of 12 hours; finally, the optimal parameters obtained by response surface methodology were:SA concentration of 4%, CaCl2 concentration of 0.5%, and immobilization time of 6 hours; under the optimal condition, the immobilized pellets strength, microalgae growth rate, TN removal rate reached-13.58%, 0.193 and 89.55%, respectively.
Artificial wastewater was used in this study, and parameters of the algae-bacteria immobilized pellets and the growth of microorganism were optimized based on treatment efficiency of livestock wastewater. The orthogonal experiment was designed for optimization of immobilized pellet strength, the growth of microorganism and removal efficiency, using multi-index full probability analysis and SPSS software analysis. The results were concluded as a set of parameters including the concentration of sodium alginate(SA) and calcium chloride(CaCl2) and the immobilization time. Then, the response surface experiment designed by analysis software Design-Expert 10 were carried out to further optimize these parameters. The results showed that the optimized parameters of orthogonal experiment were SA concentration of 3%, the CaCl2 concentration of 1%, and the immobilization time of 12 hours; finally, the optimal parameters obtained by response surface methodology were:SA concentration of 4%, CaCl2 concentration of 0.5%, and immobilization time of 6 hours; under the optimal condition, the immobilized pellets strength, microalgae growth rate, TN removal rate reached-13.58%, 0.193 and 89.55%, respectively.
2021, 39(6): 49-54.
doi: 10.13205/j.hjgc.202106008
Abstract:
In this paper, the concentration of Adenosine Triphosphate(ATP) in the aerobic tank from a biological wastewater treatment process, in addition to conventional operation indicators, was monitored at a fine chemical factory in Jiangsu Province, China. And then, biological stress index(BSI) was calculated based on the ATP data. Correlations among ATP, BSI and other conventional activated sludge indicators were investigated by using Spearman correlation coefficient method. Furthermore, the feasibility of using ATP and BSI to evaluate and predict the operation status of biochemical treatment process was explored by using locally estimated scatterplot smoothing(LOESS) method. The results showed that cATP was correlated with MLSS at a significance level of 0.01, and the Spearman correlation coefficient between them was 0.622. BSI can be used as an early warning indicator for sludge bulking, and the fluctuation of BSI was significantly correlated to COD loading, carbon-nitrogen ratio, SV30, and SVI. The LOESS curve showed that BSI can be used as an early prediction for the trend of SVI and SV30 with a 14-days lead. The analysis suggested that maintaining a relative low level of BSI(<20%) can be used in practice as a control line to evaluate the status of the activated sludge process.
In this paper, the concentration of Adenosine Triphosphate(ATP) in the aerobic tank from a biological wastewater treatment process, in addition to conventional operation indicators, was monitored at a fine chemical factory in Jiangsu Province, China. And then, biological stress index(BSI) was calculated based on the ATP data. Correlations among ATP, BSI and other conventional activated sludge indicators were investigated by using Spearman correlation coefficient method. Furthermore, the feasibility of using ATP and BSI to evaluate and predict the operation status of biochemical treatment process was explored by using locally estimated scatterplot smoothing(LOESS) method. The results showed that cATP was correlated with MLSS at a significance level of 0.01, and the Spearman correlation coefficient between them was 0.622. BSI can be used as an early warning indicator for sludge bulking, and the fluctuation of BSI was significantly correlated to COD loading, carbon-nitrogen ratio, SV30, and SVI. The LOESS curve showed that BSI can be used as an early prediction for the trend of SVI and SV30 with a 14-days lead. The analysis suggested that maintaining a relative low level of BSI(<20%) can be used in practice as a control line to evaluate the status of the activated sludge process.
2021, 39(6): 55-58,71.
doi: 10.13205/j.hjgc.202106009
Abstract:
There were a great number of rivers and lakes in China, and the constituent of sediments dredged from waters had the characteristics of high complexity and large quantity. In this paper, the utilization of dredged sediment was introduced, and its energy reutilization was put forward. The pyrolysis should be considered seriously, due to its advantages of solidification of heavy metals in sediments, less pollution emission and energy recovery. Adding suitable catalysts could improve the pyrolysis efficiency and control the distribution of reaction products. By adding suitable metallic oxide catalysts to sediments for pyrolysis, it was found that in the low-temperature pyrolysis(below 300℃), when the dosage of catalysts was 2% above, the hydrogen proportion in gas phase products could increase by about 50%. After catalytic pyrolysis treatment, the yield of biochar was 40%~45%, and the volume of solid phase products was significantly reduced.
There were a great number of rivers and lakes in China, and the constituent of sediments dredged from waters had the characteristics of high complexity and large quantity. In this paper, the utilization of dredged sediment was introduced, and its energy reutilization was put forward. The pyrolysis should be considered seriously, due to its advantages of solidification of heavy metals in sediments, less pollution emission and energy recovery. Adding suitable catalysts could improve the pyrolysis efficiency and control the distribution of reaction products. By adding suitable metallic oxide catalysts to sediments for pyrolysis, it was found that in the low-temperature pyrolysis(below 300℃), when the dosage of catalysts was 2% above, the hydrogen proportion in gas phase products could increase by about 50%. After catalytic pyrolysis treatment, the yield of biochar was 40%~45%, and the volume of solid phase products was significantly reduced.
2021, 39(6): 59-64,178.
doi: 10.13205/j.hjgc.202106010
Abstract:
In order to realize the rapid start-up and stable operation of the biofilm reactor, comparative studies were conducted on different methods of biofilm culturing in the process of MBBR of oil shale retorting wastewater treatment. The experiment was carried out by two methods of filming and domestication. Method 1 was to film the filler with simulated domestic sewage, and then domesticate the biofilm by using the oil shale retorting wastewater diluted 20 times by the simulated domestic sewage; Method 2 directly used oil shale retorting wastewater diluted 20 times with simulated domestic sewage for continuous flow film domestication. The results showed that:in the same operation stage, the growth of biofilm in method 2 was better than that in method 1, and the biomass of method 1 and method 2 were 941 mg/L and 1628 mg/L respectively, on the 35 th day. From the perspective of nitrogen and carbon removal, the start-up and stable operation time of method 2 was shorter, and the treatment efficiency was also better than that of method 1; the biofacies and SEM images showed that compared with method 2, the biofilm structure in method 2 was more compact, and the arrangement of microorganisms was more closely and the number of microorganisms was lager. So directly adopting the oil shale retorting wastewater diluted 20 times with simulated domestic sewage to carry out continuous flow film domestication was proved to be the best starting method.
In order to realize the rapid start-up and stable operation of the biofilm reactor, comparative studies were conducted on different methods of biofilm culturing in the process of MBBR of oil shale retorting wastewater treatment. The experiment was carried out by two methods of filming and domestication. Method 1 was to film the filler with simulated domestic sewage, and then domesticate the biofilm by using the oil shale retorting wastewater diluted 20 times by the simulated domestic sewage; Method 2 directly used oil shale retorting wastewater diluted 20 times with simulated domestic sewage for continuous flow film domestication. The results showed that:in the same operation stage, the growth of biofilm in method 2 was better than that in method 1, and the biomass of method 1 and method 2 were 941 mg/L and 1628 mg/L respectively, on the 35 th day. From the perspective of nitrogen and carbon removal, the start-up and stable operation time of method 2 was shorter, and the treatment efficiency was also better than that of method 1; the biofacies and SEM images showed that compared with method 2, the biofilm structure in method 2 was more compact, and the arrangement of microorganisms was more closely and the number of microorganisms was lager. So directly adopting the oil shale retorting wastewater diluted 20 times with simulated domestic sewage to carry out continuous flow film domestication was proved to be the best starting method.
2021, 39(6): 65-71.
doi: 10.13205/j.hjgc.202106011
Abstract:
A large amount of domestic garbage is generated in China every year. Landfill has become the most widely used domestic waste disposal method, due to its low cost and convenient operation. However, the generated landfill leachate seriously threatens the safety of surrounding groundwater. In order to explore the research hotspots and frontiers in the field of groundwater in landfills, this article carried out literature statistics and information mining on the Web of Science database based on analysis software CiteSpace. Combined with CiteSpace analysis graphs, it was found that the research hotspots mainly included leachate, adsorption, heavy metals, evaluation methods(analytic hierarchy process), polycyclic aromatic hydrocarbons, leachate pollution indicators, nitrification, etc. The research frontier gradually changed from the research of specific pollutants such as heavy metals and volatile organic compounds(methane, carbon) to the research of polluted areas, impact of pollutants, and geographic information systems. Based on the analysis of relevant literature and the results of CiteSpace, it was believed that there were two main development trends in the future. Firstly, based on the knowledge of geographic information system, the transmission and diffusion models of pollutants in the region should be finely described. Secondly, combined with the health risk assessment methods of contaminated areas, systematic landfill pollution remediation and treatment should be carried out.
A large amount of domestic garbage is generated in China every year. Landfill has become the most widely used domestic waste disposal method, due to its low cost and convenient operation. However, the generated landfill leachate seriously threatens the safety of surrounding groundwater. In order to explore the research hotspots and frontiers in the field of groundwater in landfills, this article carried out literature statistics and information mining on the Web of Science database based on analysis software CiteSpace. Combined with CiteSpace analysis graphs, it was found that the research hotspots mainly included leachate, adsorption, heavy metals, evaluation methods(analytic hierarchy process), polycyclic aromatic hydrocarbons, leachate pollution indicators, nitrification, etc. The research frontier gradually changed from the research of specific pollutants such as heavy metals and volatile organic compounds(methane, carbon) to the research of polluted areas, impact of pollutants, and geographic information systems. Based on the analysis of relevant literature and the results of CiteSpace, it was believed that there were two main development trends in the future. Firstly, based on the knowledge of geographic information system, the transmission and diffusion models of pollutants in the region should be finely described. Secondly, combined with the health risk assessment methods of contaminated areas, systematic landfill pollution remediation and treatment should be carried out.
2021, 39(6): 72-78.
doi: 10.13205/j.hjgc.202106012
Abstract:
The start up of partial nitrification by using free nitrous acid(FNA) to treat activated sludge was studied in a sequencing batch reactor(SBR) treating rural wastewater by recirculating a portion of the sludge through a side-stream sludge treatment unit. FNA is substantially more biocidal to NOB than to AOB. The difference was the highest at the FNA concentration of 0.48 mg/L. With 3.6 L activated sludge treated by 0.48 mg/L FNA for 24 h under anoxic condition each day, the stable partial nitrification in the sequencing batch reactor(SBR-PN) was established after 60 d accumulation, with the NH4+ removal efficiency and the nitrite accumulation rate(NAR) were both above 95%(Stage Ⅱ). The two-step feeding strategy(Stage Ⅲ) was used to replace the one-step feeding in the SBR with the aim to reduce the NO2- accumulation and N2O emission. The results showed that the maximum NO2- accumulation and N2O emission were reduced from(16.4±1.6) mg/L and(0.85±0.09) mg/L to(11.4±1.2) mg/L and(0.28±0.04) mg/L, respectively, with the TN removal efficiency of(64.0±2.5)%, the N2O yield decreased from(7.40±0.99)% to(1.33±0.26)%. Based on the selectivity of FNA on AOB and NOB, the coexistence of high NO2- and NH4+ was prevented by two-step feeding strategy of the SBR, which was beneficial to the establishment of partial nitrification and the reduction of N2O emission. PN/PS value increased from 1.42 in stage Ⅰ to 1.77 and 1.74 in stage Ⅱ and Ⅲ, additionally, SVI increased from(113±12) mL/gVSS to(129±15) mL/gVSS in stage Ⅱ and(122±13) mL/gVSS in stage Ⅲ respectively.
The start up of partial nitrification by using free nitrous acid(FNA) to treat activated sludge was studied in a sequencing batch reactor(SBR) treating rural wastewater by recirculating a portion of the sludge through a side-stream sludge treatment unit. FNA is substantially more biocidal to NOB than to AOB. The difference was the highest at the FNA concentration of 0.48 mg/L. With 3.6 L activated sludge treated by 0.48 mg/L FNA for 24 h under anoxic condition each day, the stable partial nitrification in the sequencing batch reactor(SBR-PN) was established after 60 d accumulation, with the NH4+ removal efficiency and the nitrite accumulation rate(NAR) were both above 95%(Stage Ⅱ). The two-step feeding strategy(Stage Ⅲ) was used to replace the one-step feeding in the SBR with the aim to reduce the NO2- accumulation and N2O emission. The results showed that the maximum NO2- accumulation and N2O emission were reduced from(16.4±1.6) mg/L and(0.85±0.09) mg/L to(11.4±1.2) mg/L and(0.28±0.04) mg/L, respectively, with the TN removal efficiency of(64.0±2.5)%, the N2O yield decreased from(7.40±0.99)% to(1.33±0.26)%. Based on the selectivity of FNA on AOB and NOB, the coexistence of high NO2- and NH4+ was prevented by two-step feeding strategy of the SBR, which was beneficial to the establishment of partial nitrification and the reduction of N2O emission. PN/PS value increased from 1.42 in stage Ⅰ to 1.77 and 1.74 in stage Ⅱ and Ⅲ, additionally, SVI increased from(113±12) mL/gVSS to(129±15) mL/gVSS in stage Ⅱ and(122±13) mL/gVSS in stage Ⅲ respectively.
2021, 39(6): 79-89.
doi: 10.13205/j.hjgc.202106013
Abstract:
At present, China is facing with serious pollution problems on volatile organic compounds(VOCs). Adsorption is the most widely researched and applied technology to VOCs treatment. This paper mainly introduced the principle of VOCs adsorption method and several common VOCs adsorption materials, including activated carbon, new porous carbon material, zeolite molecular sieve, clay-based adsorbent, metal organic framework and mesoporous silica. The VOCs adsorption capacity, advantages and disadvantages of the adsorbent were detailed, and its application value was also judged. In order to enhance the potential of large-scale industrial application, the VOCs adsorbents developed should meet the requirements of high adsorption capacity, high hydrophobicity, high thermal stability and excellent regeneration ability.
At present, China is facing with serious pollution problems on volatile organic compounds(VOCs). Adsorption is the most widely researched and applied technology to VOCs treatment. This paper mainly introduced the principle of VOCs adsorption method and several common VOCs adsorption materials, including activated carbon, new porous carbon material, zeolite molecular sieve, clay-based adsorbent, metal organic framework and mesoporous silica. The VOCs adsorption capacity, advantages and disadvantages of the adsorbent were detailed, and its application value was also judged. In order to enhance the potential of large-scale industrial application, the VOCs adsorbents developed should meet the requirements of high adsorption capacity, high hydrophobicity, high thermal stability and excellent regeneration ability.
2021, 39(6): 90-98.
doi: 10.13205/j.hjgc.202106014
Abstract:
Cooking fume emission is one of the sources of environmental volatile organic compounds(VOCs), which seriously threaten ambient air quality and human health. Combined with the compositions characteristics of cooking fume VOCs, the recent progress and important issues of various purification technologies for cooking fume VOCs were summarized. At the same time, the advantages and necessity of the combined technologies to control the cooking fume VOCs were also given. Finally, in view of the current problems, the developments of the combined technologies to control the cooking fume VOCs were prospected. It could provide references for the development of a green and efficient oil fume purification technology.
Cooking fume emission is one of the sources of environmental volatile organic compounds(VOCs), which seriously threaten ambient air quality and human health. Combined with the compositions characteristics of cooking fume VOCs, the recent progress and important issues of various purification technologies for cooking fume VOCs were summarized. At the same time, the advantages and necessity of the combined technologies to control the cooking fume VOCs were also given. Finally, in view of the current problems, the developments of the combined technologies to control the cooking fume VOCs were prospected. It could provide references for the development of a green and efficient oil fume purification technology.
2021, 39(6): 99-105.
doi: 10.13205/j.hjgc.202106015
Abstract:
Formaldehyde caused by indoor decoration has serious impact on human health, the need to reduce formaldehyde at room temperature is increasingly urgent. At present, room temperature catalytic oxidation is regarded as one of the most promising formaldehyde treatment methods. Zeolite molecular sieve has a large specific surface area and more adsorption sites. In this paper, with zeolite molecular sieve as the carrier, and MnOx and CeOx as reaction active sites, Mn1Cex/HZSM-5 catalyst was successfully synthesized through co-precipitation method. The catalyst degraded 96.86% of formaldehyde at room temperature and had good working stability. In addition, through a series of physical and chemical characterization analysis, it was found that Ce species could not only significantly improve the content of high-valent manganese in the catalyst, but also bring more surface hydroxyl and oxygen adsorption, thus improving the performance of the catalyst. In view of its excellent and stable performance and simple synthesis method, this highly efficient formaldehyde removal catalyst, Mn1Cex/HZSM-5 could provide a novel reference for the synthesis of formaldehyde removal catalyst at room temperature.
Formaldehyde caused by indoor decoration has serious impact on human health, the need to reduce formaldehyde at room temperature is increasingly urgent. At present, room temperature catalytic oxidation is regarded as one of the most promising formaldehyde treatment methods. Zeolite molecular sieve has a large specific surface area and more adsorption sites. In this paper, with zeolite molecular sieve as the carrier, and MnOx and CeOx as reaction active sites, Mn1Cex/HZSM-5 catalyst was successfully synthesized through co-precipitation method. The catalyst degraded 96.86% of formaldehyde at room temperature and had good working stability. In addition, through a series of physical and chemical characterization analysis, it was found that Ce species could not only significantly improve the content of high-valent manganese in the catalyst, but also bring more surface hydroxyl and oxygen adsorption, thus improving the performance of the catalyst. In view of its excellent and stable performance and simple synthesis method, this highly efficient formaldehyde removal catalyst, Mn1Cex/HZSM-5 could provide a novel reference for the synthesis of formaldehyde removal catalyst at room temperature.
2021, 39(6): 106-113.
doi: 10.13205/j.hjgc.202106016
Abstract:
In urban air quality forecast, the mass concentrations of PM2.5 were influenced by the meteorological conditions and time period. This article selected Beijing as the experimental area, analysing a variety of pollutants concentration characteristics, time characteristics and weather characteristics. The data by hour of 33 air quality monitoring stations in 2019 were used to carry out the PM2.5 forecast experiments, based on characteristics of LightGBM(light gradient boosting machine) PM2.5 mass concentration prediction model. The results showed that compared with random forests model(RF), gradient boosting decision tree model(GBDT), XGBoost model, LightGBM model had the highest prediction accuracy of PM2.5 concentration, XGBoost model came next, random forest model was the lowest. The accuracy of LightGBM model PM2.5 prediction was higher than other models, R2 was 0.9614, and training LightGBM model was fast and RAM needed less. LightGBM model on the five indicators were better than the rest of the model, and LightGBM model on PM2.5 hourly prediction had better stability and application prospects.
In urban air quality forecast, the mass concentrations of PM2.5 were influenced by the meteorological conditions and time period. This article selected Beijing as the experimental area, analysing a variety of pollutants concentration characteristics, time characteristics and weather characteristics. The data by hour of 33 air quality monitoring stations in 2019 were used to carry out the PM2.5 forecast experiments, based on characteristics of LightGBM(light gradient boosting machine) PM2.5 mass concentration prediction model. The results showed that compared with random forests model(RF), gradient boosting decision tree model(GBDT), XGBoost model, LightGBM model had the highest prediction accuracy of PM2.5 concentration, XGBoost model came next, random forest model was the lowest. The accuracy of LightGBM model PM2.5 prediction was higher than other models, R2 was 0.9614, and training LightGBM model was fast and RAM needed less. LightGBM model on the five indicators were better than the rest of the model, and LightGBM model on PM2.5 hourly prediction had better stability and application prospects.
2021, 39(6): 114-121.
doi: 10.13205/j.hjgc.202106017
Abstract:
Taiyuan, Yangquan, Changzhi, and Jincheng are four cities in Shanxi province in the Beijing-Tianjin-Hebei and its surrounding areas. To study the characteristics and sources of the carbonaceous components in PM2.5 in winter, PM2.5 samples were collected simultaneously from November 15 to December 31, 2017, and then the organic carbon(OC) and elemental carbon(EC) component contents of the samples were analyzed following the thermal/optical reflection protocol. The concentration of secondary organic carbon(SOC) was estimated using the minimum phase relation number method(MRS), and the source of carbonaceous components in PM2.5 was conducted using correlation analysis and positive matrix factorization(PMF). The average concentrations of OC and EC were(13.5±5.7) μg/m3 and(8.0±4.4) μg/m3 for each city during the sampling period, showing the spatial distribution order of Yangquan((17.3±4.5),(13.6±3.0) μg/m3)>Taiyuan((16.5±7.0),(7.8±4.2) μg/m3)> Changzhi((12.8±4.0),(7.7±2.8) μg/m3) >Jincheng((8.3±2.9),(2.9±1.3) μg/m3). OC and EC were significantly correlated with gaseous pollutants SO2, NO2 and CO in each city, indicating that coal-combustion and motor vehicle exhaust had a greater influence on the carbonaceous components. Both OC and SOC were significantly and positively correlated with relative humidity, and the ranking of SOC/OC was Taiyuan(48%)>Changzhi(45%)>Jincheng(36%)>Yangquan(34%), which was consistent with relative humidity in each city, indicating that the formation of SOC in winter in each city might mainly come from liquid phase reactions. The results of PMF analysis showed that carbonaceous components in PM2.5 in winter in each city mainly originated from coal-combustion sources(24.2%~30.4%), gasoline vehicle exhaust(21.0%~30.9%), diesel vehicle exhaust(16.1%~24.3%), and dust sources(17.2%~20.5%). The contribution of coal-combustion to carbonaceous components in PM2.5 in winter was higher in Changzhi(30.4%) than in the other three cities, gasoline vehicle exhaust was higher in Taiyuan(30.9%) than in the other cities, while diesel vehicle exhaust(24.3%) and dust sources(20.5%) were both higher in Yangquan than in the other cities.
Taiyuan, Yangquan, Changzhi, and Jincheng are four cities in Shanxi province in the Beijing-Tianjin-Hebei and its surrounding areas. To study the characteristics and sources of the carbonaceous components in PM2.5 in winter, PM2.5 samples were collected simultaneously from November 15 to December 31, 2017, and then the organic carbon(OC) and elemental carbon(EC) component contents of the samples were analyzed following the thermal/optical reflection protocol. The concentration of secondary organic carbon(SOC) was estimated using the minimum phase relation number method(MRS), and the source of carbonaceous components in PM2.5 was conducted using correlation analysis and positive matrix factorization(PMF). The average concentrations of OC and EC were(13.5±5.7) μg/m3 and(8.0±4.4) μg/m3 for each city during the sampling period, showing the spatial distribution order of Yangquan((17.3±4.5),(13.6±3.0) μg/m3)>Taiyuan((16.5±7.0),(7.8±4.2) μg/m3)> Changzhi((12.8±4.0),(7.7±2.8) μg/m3) >Jincheng((8.3±2.9),(2.9±1.3) μg/m3). OC and EC were significantly correlated with gaseous pollutants SO2, NO2 and CO in each city, indicating that coal-combustion and motor vehicle exhaust had a greater influence on the carbonaceous components. Both OC and SOC were significantly and positively correlated with relative humidity, and the ranking of SOC/OC was Taiyuan(48%)>Changzhi(45%)>Jincheng(36%)>Yangquan(34%), which was consistent with relative humidity in each city, indicating that the formation of SOC in winter in each city might mainly come from liquid phase reactions. The results of PMF analysis showed that carbonaceous components in PM2.5 in winter in each city mainly originated from coal-combustion sources(24.2%~30.4%), gasoline vehicle exhaust(21.0%~30.9%), diesel vehicle exhaust(16.1%~24.3%), and dust sources(17.2%~20.5%). The contribution of coal-combustion to carbonaceous components in PM2.5 in winter was higher in Changzhi(30.4%) than in the other three cities, gasoline vehicle exhaust was higher in Taiyuan(30.9%) than in the other cities, while diesel vehicle exhaust(24.3%) and dust sources(20.5%) were both higher in Yangquan than in the other cities.
2021, 39(6): 122-127,136.
doi: 10.13205/j.hjgc.202106018
Abstract:
Using waste PVC as a chlorinating agent, through chlorination roasting and low-temperature water leaching compound, we effectively improved the leaching efficiency of cobalt and lithium in the anode material LiCoO2 of the waste lithium-ion battery. The effects of calcination temperature, chlorinating agent and cathode material LiCoO2 material ratio, calcination time and other parameters on the leaching rate of cobalt and lithium were systematically studied. The research results showed that under the conditions of calcination temperature of 500℃, material ratio of 5:1, and calcination time of 120 min, the leaching rate of metallic cobalt reached more 95% above and the leaching rate of metallic lithium reached 99% after being immersed in water at 60℃. At the same time, X-ray diffraction(XRD), scanning electron microscope(SEM), and X-ray photoelectron spectroscopy(XPS) were used to characterize the crystal structure and surface morphology of the material before and after calcination, as well as the changes in element valence, and in-depth elucidate the process of chlorination calcination of LiCoO2, and conversion mechanism and kinetic mechanism of cobalt and lithium. Compared with the traditional wet method, fire method and biometallurgy technology, this recycling technology has lower energy intensity and higher industrial application prospects.
Using waste PVC as a chlorinating agent, through chlorination roasting and low-temperature water leaching compound, we effectively improved the leaching efficiency of cobalt and lithium in the anode material LiCoO2 of the waste lithium-ion battery. The effects of calcination temperature, chlorinating agent and cathode material LiCoO2 material ratio, calcination time and other parameters on the leaching rate of cobalt and lithium were systematically studied. The research results showed that under the conditions of calcination temperature of 500℃, material ratio of 5:1, and calcination time of 120 min, the leaching rate of metallic cobalt reached more 95% above and the leaching rate of metallic lithium reached 99% after being immersed in water at 60℃. At the same time, X-ray diffraction(XRD), scanning electron microscope(SEM), and X-ray photoelectron spectroscopy(XPS) were used to characterize the crystal structure and surface morphology of the material before and after calcination, as well as the changes in element valence, and in-depth elucidate the process of chlorination calcination of LiCoO2, and conversion mechanism and kinetic mechanism of cobalt and lithium. Compared with the traditional wet method, fire method and biometallurgy technology, this recycling technology has lower energy intensity and higher industrial application prospects.
2021, 39(6): 128-136.
doi: 10.13205/j.hjgc.202106019
Abstract:
Lignin in crop stalks is a high-molecular aromatic compound abundant in nature. It has a complex structure and is difficult to degrade by microorganisms. Therefore, the degradation and utilization of lignin in agricultural waste composting technology has attracted much attention. Studies showed that lignin was formed by the polymerization of structural units through C-C bonds and ether bonds, and the structure was stable. Composting experiments proved that fungi dominate the process of microbial degradation of lignin. The secreted laccase, manganese peroxidase and lignin peroxidase used H2O2 or O2 as the electron acceptors, which could break the bond, demethylate the aromatic hydrocarbon structure. The polyphenols or phenol produced were polymerized with amino acids, and further polycondensed into humus, which was used as a soil improvement substance to return to the field. Under laboratory and natural conditions, most fungi could degrade lignin for a long period of 30~60 days, with a degradation rate of 20%~50%. The degradation process depended on the culture conditions, the medium temperature 35~45℃ and acidic conditions were more conducive to the degradation of lignin. There was an optimal amount of carbon and nitrogen supplementation in the process of microbial metabolism, and trace Mn2+, Cu2+ inducers could be used to increase the activity of lignin degrading enzymes, which provided an important research direction for regulating the degradation of lignin and artificial humification during composting.
Lignin in crop stalks is a high-molecular aromatic compound abundant in nature. It has a complex structure and is difficult to degrade by microorganisms. Therefore, the degradation and utilization of lignin in agricultural waste composting technology has attracted much attention. Studies showed that lignin was formed by the polymerization of structural units through C-C bonds and ether bonds, and the structure was stable. Composting experiments proved that fungi dominate the process of microbial degradation of lignin. The secreted laccase, manganese peroxidase and lignin peroxidase used H2O2 or O2 as the electron acceptors, which could break the bond, demethylate the aromatic hydrocarbon structure. The polyphenols or phenol produced were polymerized with amino acids, and further polycondensed into humus, which was used as a soil improvement substance to return to the field. Under laboratory and natural conditions, most fungi could degrade lignin for a long period of 30~60 days, with a degradation rate of 20%~50%. The degradation process depended on the culture conditions, the medium temperature 35~45℃ and acidic conditions were more conducive to the degradation of lignin. There was an optimal amount of carbon and nitrogen supplementation in the process of microbial metabolism, and trace Mn2+, Cu2+ inducers could be used to increase the activity of lignin degrading enzymes, which provided an important research direction for regulating the degradation of lignin and artificial humification during composting.
2021, 39(6): 137-143.
doi: 10.13205/j.hjgc.202106020
Abstract:
The volatile fatty acid(VFA) produced in the anaerobic fermentation of excess sludge has higher application value than methane, and thus has attracted extensive attention. It was found that the anaerobic fermentation could be controlled in the acid production stage by methanogenic inhibitors, and the methanogenic process could be blocked, so as to achieve a large amount of accumulation of VFA. However, the classification of methanogenic inhibitors is not clear and the mechanism of some methanogenic inhibitors is not perfect. Therefore, according to the sources and characteristics of the substance inhibiting methanogens, methane inhibitors were divided into three categories:endogenous inhibition, exogenous inhibition and biological inhibition. We expounded several inhibitors of inhibition mechanism and the influence of the process of anaerobic fermentation to produce acid, analyzed present research situation and deficiencies of various inhibitors, pointed out that the toxicity of inhibitors inhibit and hydrolysis mechanism research was the research emphasis in the future. The competitive relationship between microorganisms in anaerobic fermentation system should be further studied, the mechanism of microorganisms in the process of acid production, and methane production inhibition by anaerobic fermentation of residual sludge should also be clarified.
The volatile fatty acid(VFA) produced in the anaerobic fermentation of excess sludge has higher application value than methane, and thus has attracted extensive attention. It was found that the anaerobic fermentation could be controlled in the acid production stage by methanogenic inhibitors, and the methanogenic process could be blocked, so as to achieve a large amount of accumulation of VFA. However, the classification of methanogenic inhibitors is not clear and the mechanism of some methanogenic inhibitors is not perfect. Therefore, according to the sources and characteristics of the substance inhibiting methanogens, methane inhibitors were divided into three categories:endogenous inhibition, exogenous inhibition and biological inhibition. We expounded several inhibitors of inhibition mechanism and the influence of the process of anaerobic fermentation to produce acid, analyzed present research situation and deficiencies of various inhibitors, pointed out that the toxicity of inhibitors inhibit and hydrolysis mechanism research was the research emphasis in the future. The competitive relationship between microorganisms in anaerobic fermentation system should be further studied, the mechanism of microorganisms in the process of acid production, and methane production inhibition by anaerobic fermentation of residual sludge should also be clarified.
2021, 39(6): 144-149.
doi: 10.13205/j.hjgc.202106021
Abstract:
Methane production from residue of anaerobic fermentative hydrogen production using combined sludge and food waste is a promising method to further exploit the potential resource of the residue of hydrogen production. This study explored the influence of inoculation volume on the methane production from the residue of anaerobic hydrogen fermentation using combined sludge and food waste under medium temperature condition, analyzed its gas and methane production performance and the changes of the substrate in the anaerobic system before and after fermentation, aimed to seek the optimum inoculation volume and the corresponding changes of the substrate in the anaerobic system, including saccharide, protein, TVFA, pH and ammonia. The results showed that, under medium temperature conditions, neither high nor low inoculation volume was conducive to methane production performance improvement. The optimum inoculation volume was 30%, then we got the fastest growth rate of methane concentration during the anaerobic fermentation, and the largest accumulative methane yield was 171.1 mL/gDS. The changes of substrate concentration in the anaerobic system proved that organic substrates were consumed greatly during fermentation, and the degradation yield of total saccharide was 39.01% and the total protein was 28.09%. It was also found that degradation rate of soluble saccharide was greater than insoluble saccharide, and the former mainly contributed to the saccharide degradation; while the degradation of insoluble and soluble amount of protein was equivalent. After the fermentation was finished, the pH in the system rose.
Methane production from residue of anaerobic fermentative hydrogen production using combined sludge and food waste is a promising method to further exploit the potential resource of the residue of hydrogen production. This study explored the influence of inoculation volume on the methane production from the residue of anaerobic hydrogen fermentation using combined sludge and food waste under medium temperature condition, analyzed its gas and methane production performance and the changes of the substrate in the anaerobic system before and after fermentation, aimed to seek the optimum inoculation volume and the corresponding changes of the substrate in the anaerobic system, including saccharide, protein, TVFA, pH and ammonia. The results showed that, under medium temperature conditions, neither high nor low inoculation volume was conducive to methane production performance improvement. The optimum inoculation volume was 30%, then we got the fastest growth rate of methane concentration during the anaerobic fermentation, and the largest accumulative methane yield was 171.1 mL/gDS. The changes of substrate concentration in the anaerobic system proved that organic substrates were consumed greatly during fermentation, and the degradation yield of total saccharide was 39.01% and the total protein was 28.09%. It was also found that degradation rate of soluble saccharide was greater than insoluble saccharide, and the former mainly contributed to the saccharide degradation; while the degradation of insoluble and soluble amount of protein was equivalent. After the fermentation was finished, the pH in the system rose.
2021, 39(6): 150-153,206.
doi: 10.13205/j.hjgc.202106022
Abstract:
At present, waste incineration power generation has become the main stream technology of domestic waste treatment in China. However, as the classification system of domestic waste had been gradually implemented nationwide, significant changes will take place in domestic waste incineration power generation. Based on above-mentioned situations, this work analyzed the impact of waste classification on the development of waste incineration power generation industry from different perspectives. In order to adapt to the change of physical and chemical properties of domestic waste after classification, the existing technology needs to be adjusted accordingly. Especially the rise of calorific value will greatly increase the power generation capacity for per ton of domestic waste, which will significantly improve the economic benefits of the project, and stimulate the enthusiasm of independent investment and operation of enterprises. According to the market situation of the incineration power generation industry, the government should flexibly adjust relevant subsidies and preferential policies. Furthermore, the waste incineration power generation industry was expected to achieve full market-oriented operation, and development mode of public participation+EPC was also expected to be popularized. For the disposal of domestic waste, the government's role of participation and supervision will also change into a single role of supervision.
At present, waste incineration power generation has become the main stream technology of domestic waste treatment in China. However, as the classification system of domestic waste had been gradually implemented nationwide, significant changes will take place in domestic waste incineration power generation. Based on above-mentioned situations, this work analyzed the impact of waste classification on the development of waste incineration power generation industry from different perspectives. In order to adapt to the change of physical and chemical properties of domestic waste after classification, the existing technology needs to be adjusted accordingly. Especially the rise of calorific value will greatly increase the power generation capacity for per ton of domestic waste, which will significantly improve the economic benefits of the project, and stimulate the enthusiasm of independent investment and operation of enterprises. According to the market situation of the incineration power generation industry, the government should flexibly adjust relevant subsidies and preferential policies. Furthermore, the waste incineration power generation industry was expected to achieve full market-oriented operation, and development mode of public participation+EPC was also expected to be popularized. For the disposal of domestic waste, the government's role of participation and supervision will also change into a single role of supervision.
2021, 39(6): 154-159.
doi: 10.13205/j.hjgc.202106023
Abstract:
Lagerstroemia indica L., a woody plant was selected as the studied subject, and the strengthening effect of types and additive amount of amendment materials on the phytoremediation of Cu-contaminated soil were conducted with the incubation experiments. The results showed that there was a more significant enhancement effect for EDTA and EDDS than organic amendment materials, and the enhancement effect was the highest at the additive amounts of 5 mmol/L EDTA or 3 mmol/L EDDS. However, the enhancement effect was found on almost all the organic amendment materials on the lower Cu-polluted soils, and more significant at the organic amendment materials/soil volume ratio of 30%. Moreover, the strengthening effect of different amendment materials on the phytoremediation of the higher Cu-polluted soil was only found at organic amendment materials/soil volume ratio of 50% for the greenery waste, agricultural organic waste and peat.
Lagerstroemia indica L., a woody plant was selected as the studied subject, and the strengthening effect of types and additive amount of amendment materials on the phytoremediation of Cu-contaminated soil were conducted with the incubation experiments. The results showed that there was a more significant enhancement effect for EDTA and EDDS than organic amendment materials, and the enhancement effect was the highest at the additive amounts of 5 mmol/L EDTA or 3 mmol/L EDDS. However, the enhancement effect was found on almost all the organic amendment materials on the lower Cu-polluted soils, and more significant at the organic amendment materials/soil volume ratio of 30%. Moreover, the strengthening effect of different amendment materials on the phytoremediation of the higher Cu-polluted soil was only found at organic amendment materials/soil volume ratio of 50% for the greenery waste, agricultural organic waste and peat.
2021, 39(6): 160-166.
doi: 10.13205/j.hjgc.202106024
Abstract:
The traditional leaching technology for heavy metal contaminated soil remediation efficiency was low, and the contaminated soil could be classified and reduced to improve the leaching efficiency. Through the development of an efficient soil classification system, soil particles could be quickly screened to improve the efficiency of soil pollution leaching remediation. The system used the principle of filtration separation, through the active pressure of the pump and the rotation of the screen surface, the particles accumulated on the screen surface were subjected to centrifugal force, gravity and liquid shear force, and the solid-liquid system was fully disturbed, which greatly reduced the bridging accumulation of soil particles on the screen surface, strengthened the screening process, and then classified the particles in the soil water solution according to the target particle size. Through the practical verification of multi-stage particle size(250~35 μm), compared with the conventional air separation system, the screening rate of the system was significantly improved, the screening efficiency and yield could be guaranteed, and the purpose of soil particle size classification was well achieved. In addition, based on the screening system, the grading leaching experiment was carried out, and the quality of the soil leached after particle size classification was reduced by about 20%. The optimal process parameters of EDTA leaching Pb contaminated soil were determined as follows:leaching solution concentration of 0.01~0.05 mol/L, pH value of 7, and leaching time of 10 h.
The traditional leaching technology for heavy metal contaminated soil remediation efficiency was low, and the contaminated soil could be classified and reduced to improve the leaching efficiency. Through the development of an efficient soil classification system, soil particles could be quickly screened to improve the efficiency of soil pollution leaching remediation. The system used the principle of filtration separation, through the active pressure of the pump and the rotation of the screen surface, the particles accumulated on the screen surface were subjected to centrifugal force, gravity and liquid shear force, and the solid-liquid system was fully disturbed, which greatly reduced the bridging accumulation of soil particles on the screen surface, strengthened the screening process, and then classified the particles in the soil water solution according to the target particle size. Through the practical verification of multi-stage particle size(250~35 μm), compared with the conventional air separation system, the screening rate of the system was significantly improved, the screening efficiency and yield could be guaranteed, and the purpose of soil particle size classification was well achieved. In addition, based on the screening system, the grading leaching experiment was carried out, and the quality of the soil leached after particle size classification was reduced by about 20%. The optimal process parameters of EDTA leaching Pb contaminated soil were determined as follows:leaching solution concentration of 0.01~0.05 mol/L, pH value of 7, and leaching time of 10 h.
2021, 39(6): 167-172.
doi: 10.13205/j.hjgc.202106025
Abstract:
Field plot experiment was conducted to investigate the effects of several common safety utilization measures such as substitute plantation, deep ploughing, application of soil remediation agents and organic fertilizers on risk management of cadmium contaminated paddy fields in Chengdu Plain. The results showed that after 3 days of the implementation of various measures, soil pH significantly increased(p<0.05), except treatment applying earthworm cast and substitute plantation; except for treatment of substitute plantation, applying earthworm cast and soil remediation, the bioavailable form of cadmium content of soil generally decreased compared with before implementation; when the substitute plantation treatment was taken separately, the cadmium content of brown rice of rice varieties selected in this experiment could not fully meet the national standard; the best cadmium reduction effect among single measures was deep ploughing, followed by the application of soil remediation agent, quicklime and modified bentonite, while the application of earthworm cast alone significantly increased(p<0.05) the cadmium content of brown rice; after No.4 combined measures(deep ploughing+applying quicklime+application of soil remediation+planting the improved variety Liangyou No.1), the cadmium content of brown rice generally met the national standard, and the average brown rice cadmium content was the lowest among all measures, which was significantly reduced by 95.52%(p<0.05) compared with the control.
Field plot experiment was conducted to investigate the effects of several common safety utilization measures such as substitute plantation, deep ploughing, application of soil remediation agents and organic fertilizers on risk management of cadmium contaminated paddy fields in Chengdu Plain. The results showed that after 3 days of the implementation of various measures, soil pH significantly increased(p<0.05), except treatment applying earthworm cast and substitute plantation; except for treatment of substitute plantation, applying earthworm cast and soil remediation, the bioavailable form of cadmium content of soil generally decreased compared with before implementation; when the substitute plantation treatment was taken separately, the cadmium content of brown rice of rice varieties selected in this experiment could not fully meet the national standard; the best cadmium reduction effect among single measures was deep ploughing, followed by the application of soil remediation agent, quicklime and modified bentonite, while the application of earthworm cast alone significantly increased(p<0.05) the cadmium content of brown rice; after No.4 combined measures(deep ploughing+applying quicklime+application of soil remediation+planting the improved variety Liangyou No.1), the cadmium content of brown rice generally met the national standard, and the average brown rice cadmium content was the lowest among all measures, which was significantly reduced by 95.52%(p<0.05) compared with the control.
2021, 39(6): 173-178.
doi: 10.13205/j.hjgc.202106026
Abstract:
Soil pollution becomes more and more serious in China, and this paper conducted a statistical analysis of 455 soil remediation projects since 2005-2019, and preliminarily expounded some characteristics, that is, the number of soil remediation projects is increasing and the main remediation methods are off-site method, accounting for 63% of the total projects. The mainstream remediation technologies are barrier/landfill(29%) and solidification/stabilization(18%). In contrast, in-situ remediation technology(54%) was the mainstream technology for site remediation technologies in the United States from 2005 to 2014, and most of them were soil vapor extraction, physical separation, solidification/stabilization, chemical remediation and bioremediation, among which the application of groundwater extraction treatment technology decreased year by year. Based on the developing tread in the USA, the remediation technologies in China was predicted to be mainly in-situ remediation.
Soil pollution becomes more and more serious in China, and this paper conducted a statistical analysis of 455 soil remediation projects since 2005-2019, and preliminarily expounded some characteristics, that is, the number of soil remediation projects is increasing and the main remediation methods are off-site method, accounting for 63% of the total projects. The mainstream remediation technologies are barrier/landfill(29%) and solidification/stabilization(18%). In contrast, in-situ remediation technology(54%) was the mainstream technology for site remediation technologies in the United States from 2005 to 2014, and most of them were soil vapor extraction, physical separation, solidification/stabilization, chemical remediation and bioremediation, among which the application of groundwater extraction treatment technology decreased year by year. Based on the developing tread in the USA, the remediation technologies in China was predicted to be mainly in-situ remediation.
2021, 39(6): 179-186,159.
doi: 10.13205/j.hjgc.202106027
Abstract:
In order to explore the variation law of soil physical and chemical properties in the process of plant restoration in coastal heavy saline-alkali, the physical and chemical properties and vegetation characteristics of five reclaimed soils in Tianjin coastal area with different dredging years were analyzed comprehensively. The results showed that:as the blowing years increase, 1) the vegetation community was descended from the single Suaeda salsa community to the Suaeda salsa-Phragmites communis-Suaeda glauca community and then to the Suaeda salsa-Tamarix chinensis-Kochia scoparia-Limonium sinense community; 2) the variety, aboveground biomass and coverage of vegetation showed an increasing trend; 0~60 cm soil layer, soil bulk density, soil salt content and soil pH showed a general trend of decrease, soil porosity and soil organic matter content showed a general trend of increase, and the content of available nitrogen, available phosphorus and available potassium showed no obvious law on the whole.The content of organic matter and available nitrogen were in the state of deficiency; 3) The results of correlation analysis showed that, there was a significant positive correlation between blowing years and vegetation richness, vegetation coverage, root depth, vegetation biomass, total soil porosity and soil organic matter, however, there was a significant negative correlation between blowing years and soil bulk density, salt content, soil pH and the content of available potassium but not with the content of available nitrogen and available phosphorus. The above research showed that the main physical and chemical properties of soil in coastal reclamation area showed certain differences and regularity with the reclamation years. Vegetation had a direct impact on improving the physical and chemical properties of coastal reclamation soil. These results provided theoretical support for the ecological construction of the coastal heavy saline-alkali land.
In order to explore the variation law of soil physical and chemical properties in the process of plant restoration in coastal heavy saline-alkali, the physical and chemical properties and vegetation characteristics of five reclaimed soils in Tianjin coastal area with different dredging years were analyzed comprehensively. The results showed that:as the blowing years increase, 1) the vegetation community was descended from the single Suaeda salsa community to the Suaeda salsa-Phragmites communis-Suaeda glauca community and then to the Suaeda salsa-Tamarix chinensis-Kochia scoparia-Limonium sinense community; 2) the variety, aboveground biomass and coverage of vegetation showed an increasing trend; 0~60 cm soil layer, soil bulk density, soil salt content and soil pH showed a general trend of decrease, soil porosity and soil organic matter content showed a general trend of increase, and the content of available nitrogen, available phosphorus and available potassium showed no obvious law on the whole.The content of organic matter and available nitrogen were in the state of deficiency; 3) The results of correlation analysis showed that, there was a significant positive correlation between blowing years and vegetation richness, vegetation coverage, root depth, vegetation biomass, total soil porosity and soil organic matter, however, there was a significant negative correlation between blowing years and soil bulk density, salt content, soil pH and the content of available potassium but not with the content of available nitrogen and available phosphorus. The above research showed that the main physical and chemical properties of soil in coastal reclamation area showed certain differences and regularity with the reclamation years. Vegetation had a direct impact on improving the physical and chemical properties of coastal reclamation soil. These results provided theoretical support for the ecological construction of the coastal heavy saline-alkali land.
2021, 39(6): 187-191.
doi: 10.13205/j.hjgc.202106028
Abstract:
High-purity magnesia was one of the most demanded and widely used products among many magnesia refractories. However, in recent years, high-purity magnesia manufacturers have faced problems such as high energy consumption, high pollution emissions, and difficulties in pollution control. This study used life cycle assessment to analyze the environmental impact of high-purity magnesia production, from cradle to gate, divided the entire process into six stages, selected 12 key environmental impact types, and established the list of material input and emissions. This study was modeled and calculated based on eBalance software. The results showed that the total environmental impact of high-purity magnesia production was 4.23×10-12, of which GWP was the largest environmental impact contribution type in the production of high-purity magnesia. The light burning stage and heavy burning stage had the largest environmental impact contribution, followed by the fine grinding stage, mining stage, and ball pressing stage, while the environmental impact contribution of the transportation stage was small.
High-purity magnesia was one of the most demanded and widely used products among many magnesia refractories. However, in recent years, high-purity magnesia manufacturers have faced problems such as high energy consumption, high pollution emissions, and difficulties in pollution control. This study used life cycle assessment to analyze the environmental impact of high-purity magnesia production, from cradle to gate, divided the entire process into six stages, selected 12 key environmental impact types, and established the list of material input and emissions. This study was modeled and calculated based on eBalance software. The results showed that the total environmental impact of high-purity magnesia production was 4.23×10-12, of which GWP was the largest environmental impact contribution type in the production of high-purity magnesia. The light burning stage and heavy burning stage had the largest environmental impact contribution, followed by the fine grinding stage, mining stage, and ball pressing stage, while the environmental impact contribution of the transportation stage was small.
2021, 39(6): 192-197.
doi: 10.13205/j.hjgc.202106029
Abstract:
Water eutrophication has seriously threatened water security and ecological civilization health, so the rational evaluation of water eutrophication is of great significance. However, the evaluation of water eutrophication degree involving many fuzzy and random factors has no unified standard and it is a complex and uncertain problem. In order to consider the stochastic fuzziness, the importance and internal information of the evaluation index in the finite interval, a comprehensive connection cloud model based on the game theory was discussed here to evaluate the water eutrophication. Case study and comparisons with the cloud model only using a single type weight and other methods showed that the proposed model was effective and feasible for the evaluation of water eutrophication, and could consider the interaction, the importance and objective information of the evaluation index. It provided a new reference for the water eutrophication evaluation.
Water eutrophication has seriously threatened water security and ecological civilization health, so the rational evaluation of water eutrophication is of great significance. However, the evaluation of water eutrophication degree involving many fuzzy and random factors has no unified standard and it is a complex and uncertain problem. In order to consider the stochastic fuzziness, the importance and internal information of the evaluation index in the finite interval, a comprehensive connection cloud model based on the game theory was discussed here to evaluate the water eutrophication. Case study and comparisons with the cloud model only using a single type weight and other methods showed that the proposed model was effective and feasible for the evaluation of water eutrophication, and could consider the interaction, the importance and objective information of the evaluation index. It provided a new reference for the water eutrophication evaluation.
2021, 39(6): 198-206.
doi: 10.13205/j.hjgc.202106030
Abstract:
The water quality of Lhalu wetland was analyzed in December 2018(dry season) and May 2019(wet season), based on field investigation and indoor analysis.Resultsshowed that total nitrogen, total phosphorus and ammonia nitrogen were 0.157~26.797 mg/L, 0.003~4.259 mg/L and 0.197~24.084 mg/L, and pH, conductivity and dissolved oxygen were 6.99~9.55, 72.85~583.50 μS/cm and 1.83~12.84 mg/L, respectively, during the dry season. Total nitrogen, total phosphorus, ammonia nitrogen, pH, conductivity and dissolved oxygen were 0.077~3.104 mg/L, 0.004~0.228 mg/L, 0.005~0.094 mg/L, 6.94~9.27, 129.90~512.87 μS/cm and 1.12~12.18 mg/L, respectively, in wet season. The average conductivity of the water body from Lhalu wetland was lower in dry season than in wet season. However, higher average dissolved oxygen, pH, total nitrogen, total phosphorus, ammonia nitrogen and COD concentrations were found in dry season than in wetland season. The average conductivity of the water body was significantly negatively correlated with pH(P<0.01), but it was significantly positively correlated with ammonia nitrogen and total phosphorus(P<0.01).Resultsfrom improved Nemero Pollution Index evaluation method showed that the water quality of Lhalu wetland was mostly Class V during the dry season and pollutant were mainly distributed in the northeast areas of Lhalu wetland; the water quality was mainly Class I and Ⅲ during the wet season, and pollutants were mainly distributed in the central and southern area of Lhalu wetland.
The water quality of Lhalu wetland was analyzed in December 2018(dry season) and May 2019(wet season), based on field investigation and indoor analysis.Resultsshowed that total nitrogen, total phosphorus and ammonia nitrogen were 0.157~26.797 mg/L, 0.003~4.259 mg/L and 0.197~24.084 mg/L, and pH, conductivity and dissolved oxygen were 6.99~9.55, 72.85~583.50 μS/cm and 1.83~12.84 mg/L, respectively, during the dry season. Total nitrogen, total phosphorus, ammonia nitrogen, pH, conductivity and dissolved oxygen were 0.077~3.104 mg/L, 0.004~0.228 mg/L, 0.005~0.094 mg/L, 6.94~9.27, 129.90~512.87 μS/cm and 1.12~12.18 mg/L, respectively, in wet season. The average conductivity of the water body from Lhalu wetland was lower in dry season than in wet season. However, higher average dissolved oxygen, pH, total nitrogen, total phosphorus, ammonia nitrogen and COD concentrations were found in dry season than in wetland season. The average conductivity of the water body was significantly negatively correlated with pH(P<0.01), but it was significantly positively correlated with ammonia nitrogen and total phosphorus(P<0.01).Resultsfrom improved Nemero Pollution Index evaluation method showed that the water quality of Lhalu wetland was mostly Class V during the dry season and pollutant were mainly distributed in the northeast areas of Lhalu wetland; the water quality was mainly Class I and Ⅲ during the wet season, and pollutants were mainly distributed in the central and southern area of Lhalu wetland.
