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2022 Vol. 40, No. 8
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2022, 40(8): 1-13,39.
doi: 10.13205/j.hjgc.202208001
Abstract:
Exploring the spatial-temporal distribution and assembly mechanisms of microbial communities have always been the goal and challenge in environmental microbial ecology. In recent years, the patterns and theories of microbial ecology have been gradually applied to engineering systems. Taxa-area relationship, taxa-time relationship, and distance decay effect have been verified in the microbial community distribution of wastewater treatment systems. In addition, microbial spatial-temporal distribution has been expanded from the discovery and description of community distribution to the driving factors identification that shape community distribution, i.e., the community assembly mechanisms. Here, we reviewed the spatial-temporal distribution and assembly mechanisms of the microbial community in wastewater treatment systems and foresee future development. We emphasized the importance of combining ecological theory with engineering practices. In the future, breakthroughs can be made in the relationships among microbial biodiversity, assembly mechanisms, and wastewater treatment performance; core taxa and rare biosphere research; and the exploitation of microbial spatio-temporal distribution and assembly mechanisms using multi-omics technology.
Exploring the spatial-temporal distribution and assembly mechanisms of microbial communities have always been the goal and challenge in environmental microbial ecology. In recent years, the patterns and theories of microbial ecology have been gradually applied to engineering systems. Taxa-area relationship, taxa-time relationship, and distance decay effect have been verified in the microbial community distribution of wastewater treatment systems. In addition, microbial spatial-temporal distribution has been expanded from the discovery and description of community distribution to the driving factors identification that shape community distribution, i.e., the community assembly mechanisms. Here, we reviewed the spatial-temporal distribution and assembly mechanisms of the microbial community in wastewater treatment systems and foresee future development. We emphasized the importance of combining ecological theory with engineering practices. In the future, breakthroughs can be made in the relationships among microbial biodiversity, assembly mechanisms, and wastewater treatment performance; core taxa and rare biosphere research; and the exploitation of microbial spatio-temporal distribution and assembly mechanisms using multi-omics technology.
2022, 40(8): 14-21.
doi: 10.13205/j.hjgc.202208002
Abstract:
Trichloroethene is a kind of soil and groundwater pollutant, which is difficult to remediate. Zero-valent iron (ZVI) has been paid much attention for many years, and whether micron zero-valent iron can be used as a practical and efficient soil and groundwater remediation material for site pollution remediation needs further study. A sand column contaminated by trichloroethene was constructed to investigate the effects of the number of micron zero valent iron (mZVI), the dosage of mZVI and the size of the medium on the removal efficiency of trichloroethene. The experimental results showed that the removal rate of mZVI was 99%, and the short-term removal effect of trichloroethene was significant. There was a positive correlation between the number of iron and removal efficiency, and 150 g of mZVI could be used to remove the pore water of the sand column under the initial concentration of TCE of nearly 105 μg/L, at the same time, the reduction removal rate of fine sand (<0.075 cm) was higher than that of coarse sand (0.075~0.15 cm). The water environment change caused by the reduction and restoration of mZVI was mainly reflected in the average decrease of 170 mV of reduction potential from oxidation state to reduction state. The results showed that the mZVI has a broad application prospect in soil and groundwater pollution remediation, and it can be used as a reference in treatment of organic chlorinated hydrocarbon pollution such as trichloroethene in soil and groundwater.
Trichloroethene is a kind of soil and groundwater pollutant, which is difficult to remediate. Zero-valent iron (ZVI) has been paid much attention for many years, and whether micron zero-valent iron can be used as a practical and efficient soil and groundwater remediation material for site pollution remediation needs further study. A sand column contaminated by trichloroethene was constructed to investigate the effects of the number of micron zero valent iron (mZVI), the dosage of mZVI and the size of the medium on the removal efficiency of trichloroethene. The experimental results showed that the removal rate of mZVI was 99%, and the short-term removal effect of trichloroethene was significant. There was a positive correlation between the number of iron and removal efficiency, and 150 g of mZVI could be used to remove the pore water of the sand column under the initial concentration of TCE of nearly 105 μg/L, at the same time, the reduction removal rate of fine sand (<0.075 cm) was higher than that of coarse sand (0.075~0.15 cm). The water environment change caused by the reduction and restoration of mZVI was mainly reflected in the average decrease of 170 mV of reduction potential from oxidation state to reduction state. The results showed that the mZVI has a broad application prospect in soil and groundwater pollution remediation, and it can be used as a reference in treatment of organic chlorinated hydrocarbon pollution such as trichloroethene in soil and groundwater.
2022, 40(8): 22-30,54.
doi: 10.13205/j.hjgc.202208003
Abstract:
To achieve high-efficiency denitrification of groundwater containing NO3--N, Fe0 was added to strengthen biological mixotrophic denitrification. The results showed that when C/N was 2.78~3.08, the average TN and NO3--N removal efficiency of reactor 1 were 39.6% and 40.1%, and they were 80.7% and 81.4% in reactor 2 adding Fe0. The results of substance transformation in a single batch of reactor 2 showed that one reaction cycle was composed of two stages: mixotrophic denitrification stage in 0~12 h and autotrophic denitrification stage in 12~24 h, and the denitrification process mainly occurred in stage of 0~12 h; the zero-order kinetics fitting results revealed that the denitrification rate was 2.38 mg/(L·h) in 0~12 h, 9.5 times of that in 12~24 h; in 4~12 h, the contribution ratio of autotrophic and heterotrophic denitrification was stable (about 4∶6), and contribution ratio of autotrophic denitrification was 100% in 12~24 h. Moreover, SEM and XRD analysis showed that there was significant microbial corrosion on the surface of Fe0, and the major products were FeOOH and bioorganic-Fe complexes. Microbial community structure analysis result indicated that Fe0 could effectively improve the diversity and richness of microbial community, and Zoogloea played a leading role in the denitrification process as the predominant genus.
To achieve high-efficiency denitrification of groundwater containing NO3--N, Fe0 was added to strengthen biological mixotrophic denitrification. The results showed that when C/N was 2.78~3.08, the average TN and NO3--N removal efficiency of reactor 1 were 39.6% and 40.1%, and they were 80.7% and 81.4% in reactor 2 adding Fe0. The results of substance transformation in a single batch of reactor 2 showed that one reaction cycle was composed of two stages: mixotrophic denitrification stage in 0~12 h and autotrophic denitrification stage in 12~24 h, and the denitrification process mainly occurred in stage of 0~12 h; the zero-order kinetics fitting results revealed that the denitrification rate was 2.38 mg/(L·h) in 0~12 h, 9.5 times of that in 12~24 h; in 4~12 h, the contribution ratio of autotrophic and heterotrophic denitrification was stable (about 4∶6), and contribution ratio of autotrophic denitrification was 100% in 12~24 h. Moreover, SEM and XRD analysis showed that there was significant microbial corrosion on the surface of Fe0, and the major products were FeOOH and bioorganic-Fe complexes. Microbial community structure analysis result indicated that Fe0 could effectively improve the diversity and richness of microbial community, and Zoogloea played a leading role in the denitrification process as the predominant genus.
2022, 40(8): 31-39.
doi: 10.13205/j.hjgc.202208004
Abstract:
Microporous aeration technology is widely used in urban river management. The changes in the structure and function of the microbial community during the intermittent aeration process and after aeration stopped are still unclear. Indoor simulation experiments were used in this paper to investigate the changing process of pollutant concentration in water bodies under different hydrodynamic conditions, as well as the response law of the structure and function of the sedimentary microbial community from the beginning of aeration to 5 days after aeration, and then 10 days. The results showed that: the DO could be maintained at a high level under different hydrodynamic conditions, both during the intermittent aeration process and after the aeration stopped, but the water pollutant concentration rose significantly after aeration stopped, and the pollutant concentration rose the most slowly under the low flow rate condition (v=0.24 m/s). In terms of microbial community composition, this phenomenon resulted from the genus Hydrogenophaga and Novosphingobium, which were related to organic matter metabolism, became the dominant genus only under the condition of low flow rate after aeration stopped and stood still for 10 days, making the organic matter in the water body more prone to degradation, and the pollutant concentration rise more slowly. In terms of microbial community function, after aeration stopped for 10 days, metabolic pathways such as energy metabolism, coenzyme and vitamin metabolism, which were usually more common in eutrophic water bodies, were more present in water bodies under static and high flow rate (v=0.93 m/s). That explained the higher pollutant concentration under these two flow rates. The research results can provide a theoretical basis for persistently improving river water quality through intermittent microporous aeration.
Microporous aeration technology is widely used in urban river management. The changes in the structure and function of the microbial community during the intermittent aeration process and after aeration stopped are still unclear. Indoor simulation experiments were used in this paper to investigate the changing process of pollutant concentration in water bodies under different hydrodynamic conditions, as well as the response law of the structure and function of the sedimentary microbial community from the beginning of aeration to 5 days after aeration, and then 10 days. The results showed that: the DO could be maintained at a high level under different hydrodynamic conditions, both during the intermittent aeration process and after the aeration stopped, but the water pollutant concentration rose significantly after aeration stopped, and the pollutant concentration rose the most slowly under the low flow rate condition (v=0.24 m/s). In terms of microbial community composition, this phenomenon resulted from the genus Hydrogenophaga and Novosphingobium, which were related to organic matter metabolism, became the dominant genus only under the condition of low flow rate after aeration stopped and stood still for 10 days, making the organic matter in the water body more prone to degradation, and the pollutant concentration rise more slowly. In terms of microbial community function, after aeration stopped for 10 days, metabolic pathways such as energy metabolism, coenzyme and vitamin metabolism, which were usually more common in eutrophic water bodies, were more present in water bodies under static and high flow rate (v=0.93 m/s). That explained the higher pollutant concentration under these two flow rates. The research results can provide a theoretical basis for persistently improving river water quality through intermittent microporous aeration.
2022, 40(8): 40-46,190.
doi: 10.13205/j.hjgc.202208005
Abstract:
This paper studied Ca2+, Mg2+ and Fe2+promoting the formation of aerobic granular sludge, discussed the removal effect of aerobic granular sludge induced by Ca2+, Mg2+and Fe2+on COD, NH4+-N and TP, studied the effects of environmental factors such as organic pollution load, temperature and aeration quantity on wastewater treatment, and then evaluated the operation stability of the granular sludge running for 60 days. The results showed that the addition of Ca2+, Mg2+ and Fe2+ could promote the granulation of AGS, and the intermediate diameter of the AGS reached 340 μm needed 18, 16, 11 days, respectively. The SVI30 min of sludge induced by Ca2+, Mg2+and Fe2+ decreased continuously and got stabilized at a lower level. The value of MLSS was higher than that of the control, especially Fe2+, and its dehydrogenase activity was higher. The granular sludge induced by Ca2+, Mg2+ and Fe2+ all had a good treatment effect on COD, NH4+-N and TP, significantly higher than the control group, especially the granular sludge induced by Fe2+. The granular sludge induced by Fe2+ showed a better removal effect on COD, NH4+-N and TP in wastewater under ultra-low temperature (4 ℃), ultra-high temperature (40 ℃) and insufficient aeration (1 L/min). The granular sludge induced by Ca2+, Mg2+ and Fe2+ had good stability in sewage treatment in 60 days’ running. The removal rate of COD, NH4+-N and TP in AGS induced by Fe2+ still came up with 96.3%, 96.8% and 88.7%.
This paper studied Ca2+, Mg2+ and Fe2+promoting the formation of aerobic granular sludge, discussed the removal effect of aerobic granular sludge induced by Ca2+, Mg2+and Fe2+on COD, NH4+-N and TP, studied the effects of environmental factors such as organic pollution load, temperature and aeration quantity on wastewater treatment, and then evaluated the operation stability of the granular sludge running for 60 days. The results showed that the addition of Ca2+, Mg2+ and Fe2+ could promote the granulation of AGS, and the intermediate diameter of the AGS reached 340 μm needed 18, 16, 11 days, respectively. The SVI30 min of sludge induced by Ca2+, Mg2+and Fe2+ decreased continuously and got stabilized at a lower level. The value of MLSS was higher than that of the control, especially Fe2+, and its dehydrogenase activity was higher. The granular sludge induced by Ca2+, Mg2+ and Fe2+ all had a good treatment effect on COD, NH4+-N and TP, significantly higher than the control group, especially the granular sludge induced by Fe2+. The granular sludge induced by Fe2+ showed a better removal effect on COD, NH4+-N and TP in wastewater under ultra-low temperature (4 ℃), ultra-high temperature (40 ℃) and insufficient aeration (1 L/min). The granular sludge induced by Ca2+, Mg2+ and Fe2+ had good stability in sewage treatment in 60 days’ running. The removal rate of COD, NH4+-N and TP in AGS induced by Fe2+ still came up with 96.3%, 96.8% and 88.7%.
2022, 40(8): 47-54.
doi: 10.13205/j.hjgc.202208006
Abstract:
Gehlenite ceramsites were prepared through calcination, with industrial solid wastes lime mud and fly ash as the raw materials. Then, the ceramsites were modified by hydrothermal reaction of NaOH solution and finally applied to the adsorption of manganese-containing wastewater. The ceramsites before and after the modification were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), to explore the modification mechanism. Under different modification conditions, such as the concentration of NaOH solution and the temperature of the hydrothermal reaction, the adsorption efficiency of Mn2+ by the ceramsites was detected. Thus, the optimum modification conditions and the adsorption mechanism of Mn2+ were determined. The results showed that after modification, the main mineral phase of the ceramsites was still gehlenite, but a new phase, Ca(OH)2 was generated because of the activation of the partial calcium element. Accordingly, the alkalinity of the ceramsites was increased, significantly improving the removal rate of Mn2+ and shortening the adsorption equilibrium time. The concentrations of NaOH solution of 4, 3 mol/L and the temperature of 160 ℃ were the optimum modification conditions of the two ceramsites, respectively. For the adsorption of Mn2+ by the modified ceramsites, the adsorption equilibrium was achieved at 10~15 min, and the removal rate was close to 100%. During the adsorption process, Mn2+ in solution was reacted with OH- released from the ceramsites to form white Mn(OH)2 and then quickly oxidized to brown MnO(OH)2, which was evenly adsorbed on the surface of the ceramsites. This technology not only realized the utilization of solid wastes, but also achieved the purpose of Treating Waste with Waste.
Gehlenite ceramsites were prepared through calcination, with industrial solid wastes lime mud and fly ash as the raw materials. Then, the ceramsites were modified by hydrothermal reaction of NaOH solution and finally applied to the adsorption of manganese-containing wastewater. The ceramsites before and after the modification were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), to explore the modification mechanism. Under different modification conditions, such as the concentration of NaOH solution and the temperature of the hydrothermal reaction, the adsorption efficiency of Mn2+ by the ceramsites was detected. Thus, the optimum modification conditions and the adsorption mechanism of Mn2+ were determined. The results showed that after modification, the main mineral phase of the ceramsites was still gehlenite, but a new phase, Ca(OH)2 was generated because of the activation of the partial calcium element. Accordingly, the alkalinity of the ceramsites was increased, significantly improving the removal rate of Mn2+ and shortening the adsorption equilibrium time. The concentrations of NaOH solution of 4, 3 mol/L and the temperature of 160 ℃ were the optimum modification conditions of the two ceramsites, respectively. For the adsorption of Mn2+ by the modified ceramsites, the adsorption equilibrium was achieved at 10~15 min, and the removal rate was close to 100%. During the adsorption process, Mn2+ in solution was reacted with OH- released from the ceramsites to form white Mn(OH)2 and then quickly oxidized to brown MnO(OH)2, which was evenly adsorbed on the surface of the ceramsites. This technology not only realized the utilization of solid wastes, but also achieved the purpose of Treating Waste with Waste.
2022, 40(8): 55-61.
doi: 10.13205/j.hjgc.202208007
Abstract:
In order to reduce and alleviate the corrosion and scaling of equipment during the evaporation process of concentrated leachate, the removal efficiency of Ca2+ and Mg2+ in concentrated leachate was investigated by the combination of alkali solution and compound reagents. The chemical composition and mineral characteristics of precipitates were analyzed by various methods. The influence of water quality parameters and scaling amount during the removal of Ca2+ and Mg2+ were also explored. The results showed that: 1) when the volume addition ratio of 7.5 mol/L NaOH was 3%, the Ca2+ and Mg2+ were effectively removed after 60 min of reaction, and the removal efficiencies were 89.49% and 98.45% respectively, but the sedimentation performance was poor under this condition; 2) when NaOH combined with diatomite and Ca(OH)2 was used, the sedimentation performance of precipitates was significantly improved, and the removal efficiency of Ca2+ and Mg2+ were not significantly affected. The sedimentation ratio was 36.84% when 1% Ca(OH)2 was added, significantly lower than single NaOH solution of 75.61%. 3) according to the analysis of chemical composition and mineral characteristics of precipitates, the main minerals were Mg(OH)2, Mg5(CO3)4(OH)2·4H2O, NaCl and KCl; 4)the simulated experiment for evaporation of raw concentrated leachate and supernatant showed that the amount of scaling after alkali treatment was lower than that of raw concentrated leachate when pH was adjusted to 5.0.
In order to reduce and alleviate the corrosion and scaling of equipment during the evaporation process of concentrated leachate, the removal efficiency of Ca2+ and Mg2+ in concentrated leachate was investigated by the combination of alkali solution and compound reagents. The chemical composition and mineral characteristics of precipitates were analyzed by various methods. The influence of water quality parameters and scaling amount during the removal of Ca2+ and Mg2+ were also explored. The results showed that: 1) when the volume addition ratio of 7.5 mol/L NaOH was 3%, the Ca2+ and Mg2+ were effectively removed after 60 min of reaction, and the removal efficiencies were 89.49% and 98.45% respectively, but the sedimentation performance was poor under this condition; 2) when NaOH combined with diatomite and Ca(OH)2 was used, the sedimentation performance of precipitates was significantly improved, and the removal efficiency of Ca2+ and Mg2+ were not significantly affected. The sedimentation ratio was 36.84% when 1% Ca(OH)2 was added, significantly lower than single NaOH solution of 75.61%. 3) according to the analysis of chemical composition and mineral characteristics of precipitates, the main minerals were Mg(OH)2, Mg5(CO3)4(OH)2·4H2O, NaCl and KCl; 4)the simulated experiment for evaporation of raw concentrated leachate and supernatant showed that the amount of scaling after alkali treatment was lower than that of raw concentrated leachate when pH was adjusted to 5.0.
2022, 40(8): 62-68,130.
doi: 10.13205/j.hjgc.202208008
Abstract:
The regeneration and recycling of activated carbon are important to reduce the cost of VOCs treatment by adsorption method and to reduce the amount of hazardous waste generated. The activated carbon adsorbed ethyl acetate was regenerated by vacuum-thermal regeneration method, the effect of regeneration temperature and holding time on the regeneration effect of activated carbon, and the recycling performance of activated carbon by vacuum-thermal regeneration method were investigated. The results showed that the loss rate of activated carbon increased with the increase of regeneration temperature, and the maximum loss rate of activated carbon was only 0.7%, when the regeneration temperature was less than 200 ℃; the desorption rate of ethyl acetate reached 93.8% and the equilibrium adsorption capacity of activated carbon after regeneration was 108.1 mg/g at the optimal experimental condition of 200 ℃ and holding time of 30 min. The specific surface area and pore size distribution showed that vacuum-thermal regeneration had almost no effect on the structure of activated carbon when the temperature was lower than 200 ℃; the specific surface area of activated carbon increased by 22, 19, 42 m2/g after regeneration at 300, 400, 500 ℃, respectively, compared with that of the new activated carbon. After six cycles of regeneration under optimal regeneration conditions, the equilibrium adsorption capacity of activated carbon for ethyl acetate reached 97% of that of the new activated carbon, indicating that vacuum-thermal regeneration method had good regeneration performance for activated carbon.
The regeneration and recycling of activated carbon are important to reduce the cost of VOCs treatment by adsorption method and to reduce the amount of hazardous waste generated. The activated carbon adsorbed ethyl acetate was regenerated by vacuum-thermal regeneration method, the effect of regeneration temperature and holding time on the regeneration effect of activated carbon, and the recycling performance of activated carbon by vacuum-thermal regeneration method were investigated. The results showed that the loss rate of activated carbon increased with the increase of regeneration temperature, and the maximum loss rate of activated carbon was only 0.7%, when the regeneration temperature was less than 200 ℃; the desorption rate of ethyl acetate reached 93.8% and the equilibrium adsorption capacity of activated carbon after regeneration was 108.1 mg/g at the optimal experimental condition of 200 ℃ and holding time of 30 min. The specific surface area and pore size distribution showed that vacuum-thermal regeneration had almost no effect on the structure of activated carbon when the temperature was lower than 200 ℃; the specific surface area of activated carbon increased by 22, 19, 42 m2/g after regeneration at 300, 400, 500 ℃, respectively, compared with that of the new activated carbon. After six cycles of regeneration under optimal regeneration conditions, the equilibrium adsorption capacity of activated carbon for ethyl acetate reached 97% of that of the new activated carbon, indicating that vacuum-thermal regeneration method had good regeneration performance for activated carbon.
2022, 40(8): 69-77.
doi: 10.13205/j.hjgc.202208009
Abstract:
In the paper, Cu and Mn bimetallic organic framework materials were prepared using the gas-assisted ion replacement method. A series of CuO-Cu1.5Mn1.5O4 composite oxides were prepared through controlled calcination, and the effect of various n(Mn)/n(Cu) on the catalytic performance of propane total oxidation was studied. The results revealed that with an increase in the n(Mn)/n(Cu), CuO-Cu1.5Mn1.5O4 catalysts showed enhanced propane total oxidation catalytic activities. When n(Mn)/n(Cu) was 31∶69, the complete combustion temperature (T90) of propane was just 309.8 ℃, signifying that the activity was much higher than that of CuO and Mn2O3. The experimental and density functional theory (DFT) calculation results revealed that the synergetic effect of Mn and Cu increased the n(Mn4+)/n(Mn3+) and n(Cu+)/n(Cu2+) on the surface, which enhanced the redox ability at low-temperature. Meanwhile, the increase of n(Cu+)/n(Cu2+) led to a higher concentration of oxygen vacancies, and made it easier to adsorb and activate oxygen and propane molecules on the surface, thereby boosted the propane catalytic oxidation performance.
In the paper, Cu and Mn bimetallic organic framework materials were prepared using the gas-assisted ion replacement method. A series of CuO-Cu1.5Mn1.5O4 composite oxides were prepared through controlled calcination, and the effect of various n(Mn)/n(Cu) on the catalytic performance of propane total oxidation was studied. The results revealed that with an increase in the n(Mn)/n(Cu), CuO-Cu1.5Mn1.5O4 catalysts showed enhanced propane total oxidation catalytic activities. When n(Mn)/n(Cu) was 31∶69, the complete combustion temperature (T90) of propane was just 309.8 ℃, signifying that the activity was much higher than that of CuO and Mn2O3. The experimental and density functional theory (DFT) calculation results revealed that the synergetic effect of Mn and Cu increased the n(Mn4+)/n(Mn3+) and n(Cu+)/n(Cu2+) on the surface, which enhanced the redox ability at low-temperature. Meanwhile, the increase of n(Cu+)/n(Cu2+) led to a higher concentration of oxygen vacancies, and made it easier to adsorb and activate oxygen and propane molecules on the surface, thereby boosted the propane catalytic oxidation performance.
2022, 40(8): 78-83.
doi: 10.13205/j.hjgc.202208010
Abstract:
To study the impact of evaporation-condensation aerosol polydispersity on the penetration measurement experiment, the penetrations of various filter materials from low to high filtration efficiency were measured at different particle count median diameter and face filtration velocity. The true penetration curves at typical filtration velocity were obtained by corrected calculation, and compared with the test penetration, which was found that all the most penetrating particle sizes were all in the range of 0.1 μm to 0.3 μm. The most penetrating particle size measured in the test had a negative deviation, and the relative error with the corrected value was very small, with a maximum value within 1.5%. The extreme value of the penetration error caused by the polydispersity of the test aerosol appeared at the position of the most easily penetrated particle size, showing a negative deviation. The relative error of the low-efficiency filter material was small, with the minimum value of 2.4%, and the maximum value of the high-efficiency filter material was about 10%. It was concluded that in the range of the most penetrating particle size, the most easily penetrated particle size and penetration measured by evaporation-condensation monodisperse aerosol were valid.
To study the impact of evaporation-condensation aerosol polydispersity on the penetration measurement experiment, the penetrations of various filter materials from low to high filtration efficiency were measured at different particle count median diameter and face filtration velocity. The true penetration curves at typical filtration velocity were obtained by corrected calculation, and compared with the test penetration, which was found that all the most penetrating particle sizes were all in the range of 0.1 μm to 0.3 μm. The most penetrating particle size measured in the test had a negative deviation, and the relative error with the corrected value was very small, with a maximum value within 1.5%. The extreme value of the penetration error caused by the polydispersity of the test aerosol appeared at the position of the most easily penetrated particle size, showing a negative deviation. The relative error of the low-efficiency filter material was small, with the minimum value of 2.4%, and the maximum value of the high-efficiency filter material was about 10%. It was concluded that in the range of the most penetrating particle size, the most easily penetrated particle size and penetration measured by evaporation-condensation monodisperse aerosol were valid.
2022, 40(8): 84-89.
doi: 10.13205/j.hjgc.202208011
Abstract:
In order to study the influencing factors of moisture content and permeability of the consolidated body in the process of chemical consolidation treatment of waste slurry, super absorbent polymer (SAP) and cement were selected as the consolidation materials, and indoor consolidation tests were carried out on the waste mud to study different consolidations. The effects of materials, material ratios, and consolidation time on moisture content of the consolidated body were tested on a permeation instrument modified from a medium pressure filter loss instrument, to study the effects of the above factors on permeability. The results showed that SAP over 5% in 24 hours was better in reducing moisture content than cement, and after 168 h, cement with the same ratio was better than SAP. The permeability of the SAP group was better than that of the cement group, and the ratio was increased to 7%. After the consolidation time reached 72 h, the permeability of the SAP group didn’t continue to decrease but increased. When the cement ratio was below 7%, when increasing the ratio to permeability, the effect of sexual blocking became more significant. After analysis, there was a positive correlation between the permeability of the consolidated body and the moisture content, and the moisture content affected the permeability by changing the number of seepage channels. 5% SAP and 7% cement made the waste slurry achieve a better consolidation effect.
In order to study the influencing factors of moisture content and permeability of the consolidated body in the process of chemical consolidation treatment of waste slurry, super absorbent polymer (SAP) and cement were selected as the consolidation materials, and indoor consolidation tests were carried out on the waste mud to study different consolidations. The effects of materials, material ratios, and consolidation time on moisture content of the consolidated body were tested on a permeation instrument modified from a medium pressure filter loss instrument, to study the effects of the above factors on permeability. The results showed that SAP over 5% in 24 hours was better in reducing moisture content than cement, and after 168 h, cement with the same ratio was better than SAP. The permeability of the SAP group was better than that of the cement group, and the ratio was increased to 7%. After the consolidation time reached 72 h, the permeability of the SAP group didn’t continue to decrease but increased. When the cement ratio was below 7%, when increasing the ratio to permeability, the effect of sexual blocking became more significant. After analysis, there was a positive correlation between the permeability of the consolidated body and the moisture content, and the moisture content affected the permeability by changing the number of seepage channels. 5% SAP and 7% cement made the waste slurry achieve a better consolidation effect.
2022, 40(8): 90-95.
doi: 10.13205/j.hjgc.202208012
Abstract:
Methane production by anaerobic digestion is popular biotechnology to utilize the wanted waste activated sludge (WAS). But the hydrolysis is known as the rate-limiting step of WAS fermentation. The uronic acids (such as alginate and polygalacturonic acid) in WAS can form hydrogels with cationic ions (i.e. Ca2+) in wastewater, which can maintain sludge structure and retard the microbial hydrolysis. Thus, these organics are deemed as the main components of structural extracellular polymeric substances. In this work, an alginate-degrading consortium (ADC) with high activity was enriched in a mesophilic chemostat using alginate as the substrate. The results showed that the enriched ADC could notably enhance methane production from WAS. The methane yield increased by 53.6% under a low ratio of inoculum to WAS of 0.03 g/g [m(ADC)∶m(VSS)]. Moreover, the typical organic components of WAS, including polygalacturonic acid, dextran, and casein, could be utilized by the enriched ADC. The genus Bacteroides (96.3%) was identified as the dominant bacteria in ADC by an Illumina Miseq high-throughput sequencing. Therefore, this work provided a new microbial method for biochemical production in WAS.
Methane production by anaerobic digestion is popular biotechnology to utilize the wanted waste activated sludge (WAS). But the hydrolysis is known as the rate-limiting step of WAS fermentation. The uronic acids (such as alginate and polygalacturonic acid) in WAS can form hydrogels with cationic ions (i.e. Ca2+) in wastewater, which can maintain sludge structure and retard the microbial hydrolysis. Thus, these organics are deemed as the main components of structural extracellular polymeric substances. In this work, an alginate-degrading consortium (ADC) with high activity was enriched in a mesophilic chemostat using alginate as the substrate. The results showed that the enriched ADC could notably enhance methane production from WAS. The methane yield increased by 53.6% under a low ratio of inoculum to WAS of 0.03 g/g [m(ADC)∶m(VSS)]. Moreover, the typical organic components of WAS, including polygalacturonic acid, dextran, and casein, could be utilized by the enriched ADC. The genus Bacteroides (96.3%) was identified as the dominant bacteria in ADC by an Illumina Miseq high-throughput sequencing. Therefore, this work provided a new microbial method for biochemical production in WAS.
2022, 40(8): 96-101.
doi: 10.13205/j.hjgc.202208013
Abstract:
To resolve the lack of medical sludge treatment technologies, the disinfection effect of alkaline disinfectants coupled with low-temperature heat treatment on medical wastewater sludge was evaluated by using Bacillus subtilis var. niger Spore as the indicator bacteria. The results indicated that the optimum dosage of CaO disinfection for medical wastewater sludge was 5%. The heat treatment temperature needed to be 70 ℃ above, and medical wastewater sludge disinfection requirements could be met by treating at 80 ℃ for 2 h, or 70 ℃ for 4 h. Compared with 5% CaO alone, adding 1% NaOH could shorten the treatment time at 80 ℃ and 70 ℃ to 1h and 3 h, respectively. The dewatering performance of medical wastewater sludge was effectively improved after alkaline disinfection. The results of this study can provide a theoretical basis and data support for the formation of centralized disinfection treatment technology for medical wastewater sludge.
To resolve the lack of medical sludge treatment technologies, the disinfection effect of alkaline disinfectants coupled with low-temperature heat treatment on medical wastewater sludge was evaluated by using Bacillus subtilis var. niger Spore as the indicator bacteria. The results indicated that the optimum dosage of CaO disinfection for medical wastewater sludge was 5%. The heat treatment temperature needed to be 70 ℃ above, and medical wastewater sludge disinfection requirements could be met by treating at 80 ℃ for 2 h, or 70 ℃ for 4 h. Compared with 5% CaO alone, adding 1% NaOH could shorten the treatment time at 80 ℃ and 70 ℃ to 1h and 3 h, respectively. The dewatering performance of medical wastewater sludge was effectively improved after alkaline disinfection. The results of this study can provide a theoretical basis and data support for the formation of centralized disinfection treatment technology for medical wastewater sludge.
MINERAL COMPONENTS AND HEAVY METAL POLLUTION CHARACTERISTICS IN WASTE INCINERATION FLY ASH IN FUZHOU
2022, 40(8): 102-109.
doi: 10.13205/j.hjgc.202208014
Abstract:
This study collected fly ash from an incineration power plant in Fuzhou, analyzed and compared the mineral components and heavy metal pollution characteristics in different areas in China. The results showed that the main mineral included the soluble chloride salts(NaCl, KCl) and insoluble chloride salts(AlOCl), apart from CaCO3 and SiO2. The order of heavy metal total amount was Zn>Pb>Cu>Cd>Cr>Ni, and the total amount of Zn and Pb was higher, the same as that in some other areas in China; the leaching concentration of Pb exceeded the standard limit, GB 16889—2008 in the leaching toxicity test. The morphological analysis also showed that the unstable state of Cd (83.3%) and Cu (66.2%) accounted for high proportions, and that of Pb (36.6%) and Zn (47.0%) also accounted for certain proportions. Compared with the short-term leaching and the types of extractants (UPW, acetic acid and HCl), 5 mol/L HCl had a significant leaching effect under the long-term leaching condition, and the leaching concentrations of Zn and Pb significantly rose, and Zn leaching concentration was the highest in all heavy metal elements; the leaching concentrations of Cu, Cd, Cr, and Ni were relatively lower under the influence of total amount and speciation of heavy metal. Therefore, long-term storage of fly ash in the environment still possessed a high potential risk. The mineral components and heavy metal pollution characteristics of fly ash in different areas have certain universal laws and regional characteristics, which can provide data support for the development of fly ash immobilization and stabilization methods.
This study collected fly ash from an incineration power plant in Fuzhou, analyzed and compared the mineral components and heavy metal pollution characteristics in different areas in China. The results showed that the main mineral included the soluble chloride salts(NaCl, KCl) and insoluble chloride salts(AlOCl), apart from CaCO3 and SiO2. The order of heavy metal total amount was Zn>Pb>Cu>Cd>Cr>Ni, and the total amount of Zn and Pb was higher, the same as that in some other areas in China; the leaching concentration of Pb exceeded the standard limit, GB 16889—2008 in the leaching toxicity test. The morphological analysis also showed that the unstable state of Cd (83.3%) and Cu (66.2%) accounted for high proportions, and that of Pb (36.6%) and Zn (47.0%) also accounted for certain proportions. Compared with the short-term leaching and the types of extractants (UPW, acetic acid and HCl), 5 mol/L HCl had a significant leaching effect under the long-term leaching condition, and the leaching concentrations of Zn and Pb significantly rose, and Zn leaching concentration was the highest in all heavy metal elements; the leaching concentrations of Cu, Cd, Cr, and Ni were relatively lower under the influence of total amount and speciation of heavy metal. Therefore, long-term storage of fly ash in the environment still possessed a high potential risk. The mineral components and heavy metal pollution characteristics of fly ash in different areas have certain universal laws and regional characteristics, which can provide data support for the development of fly ash immobilization and stabilization methods.
2022, 40(8): 110-117.
doi: 10.13205/j.hjgc.202208015
Abstract:
Aiming at the problem of resource utilization of coal-fired circulating fluidized bed boiler (CFB) ash and slag, the CFB ash and slag were ultra-refined by a supersonic steam mill. The cement-based cementitious properties of CFB ash ultrafine powder and their mixtures were compared and studied, including compressive strength, water requirement of normal consistency, stability and setting time. The results showed that under the premise of meeting the P·F 42.5 strength standard, the incorporation of CFB original ash in cement reached 40%, the CFB ash ultrafine powder was 55%, the CFB slag ultrafine powder was 25%, and the incorporation of CFB ash and slag wltrafine powder reached 40% if the CFB ash and slag were mixed according to 2∶1. The incorporation of CFB slag ultrafine powder significantly increased the water requirement of normal consistency of the cement system. A large dosage (≥70%) would lead to the early setting of the cementitious system, and less dosage (≤55%) would show retarding effect. Although the addition of solid waste superfine powder led to the deterioration of volume stability of the cement system, it still met the requirements of China’s national standard, GB 175—2020 Common Portland Cement (＜5 mm).
Aiming at the problem of resource utilization of coal-fired circulating fluidized bed boiler (CFB) ash and slag, the CFB ash and slag were ultra-refined by a supersonic steam mill. The cement-based cementitious properties of CFB ash ultrafine powder and their mixtures were compared and studied, including compressive strength, water requirement of normal consistency, stability and setting time. The results showed that under the premise of meeting the P·F 42.5 strength standard, the incorporation of CFB original ash in cement reached 40%, the CFB ash ultrafine powder was 55%, the CFB slag ultrafine powder was 25%, and the incorporation of CFB ash and slag wltrafine powder reached 40% if the CFB ash and slag were mixed according to 2∶1. The incorporation of CFB slag ultrafine powder significantly increased the water requirement of normal consistency of the cement system. A large dosage (≥70%) would lead to the early setting of the cementitious system, and less dosage (≤55%) would show retarding effect. Although the addition of solid waste superfine powder led to the deterioration of volume stability of the cement system, it still met the requirements of China’s national standard, GB 175—2020 Common Portland Cement (＜5 mm).
2022, 40(8): 118-124,95.
doi: 10.13205/j.hjgc.202208016
Abstract:
In this study, the coupled adsorption-advanced oxidation system was established, based on the nanoscale zero-valent iron-based biochar (nZVI-BC) combined with sodium peroxodisulfate (PDS) or potassium peroxymonosulfate (PMS), and then applied in the investigation of oxytetracycline (OTC) removal. Based on this, the performance of OTC removal with different condition factors, including PDS/PMS concentration, nZVI-BC dosage, OTC concentration and initial pH, was investigated. The generated reactive oxygen species for OTC removal were also explored. The results showed that OTC removal efficiency was more than 80% under the conditions of 0.20 mmol/L PDS/PMS, 0.01 g nZVI-BC, 50 mg/L OTC and an original pH value of 5.0±0.1. In nZVI-BC/PDS system, SO4-· played a dominant role in OTC degradation (with a contribution of 57.00%), while SO4-·, O2-·, and1O2 were significant roles in nZVI-BC/PMS.
In this study, the coupled adsorption-advanced oxidation system was established, based on the nanoscale zero-valent iron-based biochar (nZVI-BC) combined with sodium peroxodisulfate (PDS) or potassium peroxymonosulfate (PMS), and then applied in the investigation of oxytetracycline (OTC) removal. Based on this, the performance of OTC removal with different condition factors, including PDS/PMS concentration, nZVI-BC dosage, OTC concentration and initial pH, was investigated. The generated reactive oxygen species for OTC removal were also explored. The results showed that OTC removal efficiency was more than 80% under the conditions of 0.20 mmol/L PDS/PMS, 0.01 g nZVI-BC, 50 mg/L OTC and an original pH value of 5.0±0.1. In nZVI-BC/PDS system, SO4-· played a dominant role in OTC degradation (with a contribution of 57.00%), while SO4-·, O2-·, and1O2 were significant roles in nZVI-BC/PMS.
2022, 40(8): 125-130.
doi: 10.13205/j.hjgc.202208017
Abstract:
In this work, H2O2 oxidation combined with soil chemical washing to remove hexavalent chromium and total chromium of contaminated soil collected from the electroplating factory in Hefei was developed. The effects of concentration of hydrogen peroxide, and eluting agents on remediation efficiency of chromium-contaminated soil were evaluated via batch experiment. The maximum removal efficiencies of hexavalent chromium and total chromium could achieve 51.5% and 20.9% for 10% H2O2 oxidation treatment. The soil was also washed by hydrochloric acid alone and citric acid alone, respectively, and the hexavalent chromium concentrations that remained in the soil under these conditions still exceeded the standard value in Soil Environmental Quality, Risk Control Standard for Soil Contamination of Development Land in China. However, hexavalent chromium and total chromium removal efficiency were promoted after combining H2O2 oxidation with hydrochloric acid washing, achieving 85.5% and 50.6% when the concentration of hydrochloric acid was 1.0 mol/L and the solid-liquid ratio was 1∶4. The hexavalent chromium that remained in the soil was as low as 4.4 mg/kg, which was lower than the standard value. The morphological analysis by Tessier’s five-step extraction showed that the proportion of residual form obtained in the soil increased from 44.7% to 93.4% after this technology was applied, which significantly reduced the risk of chromium re-release. This work can provide a way for remediation and utilization of heavy metal chromium from chromium-contaminated soil.
In this work, H2O2 oxidation combined with soil chemical washing to remove hexavalent chromium and total chromium of contaminated soil collected from the electroplating factory in Hefei was developed. The effects of concentration of hydrogen peroxide, and eluting agents on remediation efficiency of chromium-contaminated soil were evaluated via batch experiment. The maximum removal efficiencies of hexavalent chromium and total chromium could achieve 51.5% and 20.9% for 10% H2O2 oxidation treatment. The soil was also washed by hydrochloric acid alone and citric acid alone, respectively, and the hexavalent chromium concentrations that remained in the soil under these conditions still exceeded the standard value in Soil Environmental Quality, Risk Control Standard for Soil Contamination of Development Land in China. However, hexavalent chromium and total chromium removal efficiency were promoted after combining H2O2 oxidation with hydrochloric acid washing, achieving 85.5% and 50.6% when the concentration of hydrochloric acid was 1.0 mol/L and the solid-liquid ratio was 1∶4. The hexavalent chromium that remained in the soil was as low as 4.4 mg/kg, which was lower than the standard value. The morphological analysis by Tessier’s five-step extraction showed that the proportion of residual form obtained in the soil increased from 44.7% to 93.4% after this technology was applied, which significantly reduced the risk of chromium re-release. This work can provide a way for remediation and utilization of heavy metal chromium from chromium-contaminated soil.
2022, 40(8): 131-135,184.
doi: 10.13205/j.hjgc.202208018
Abstract:
The remediation and restoration of soil contaminated by heavy metals is considered to be of great significance to the prevention and control of environmental pollution. In this paper, a complex contaminated soil on the surface with Pb and As in a smelter in Henan was taken as the research object. By applying different DC voltages, electrokinetic remediation was carried out. Then based on the mobility and form changes, the restoration effect was evaluated. During the restoration process, we studied the current change, Pb/As migration law, soil moisture content, electrical conductivity, pH value, and Pb/As speciation transformation. The results showed that the change of applied DC voltage had a stronger effect on the migration of Pb in the soil, but a weaker effect on the migration of As. When the applied DC voltage was 10 V, As content in the cathode region of the sample soil was reduced to 43.18 mg/kg; and when the applied DC voltage was 30 V, the Pb content in the cathode region was reduced to 334 mg/kg. The operation of applying low-voltage current first and then high-voltage current was more effective to improve the electrokinetic remediation effect of Pb and As compound contaminated soil. In the restored soil, the proportion of weak acid state of Pb and As decreased, and the proportion of reducible state increased. The content of Pb and As in soil was lower than the screening value for construction land Class Ⅰ in GB 36600—2018.
The remediation and restoration of soil contaminated by heavy metals is considered to be of great significance to the prevention and control of environmental pollution. In this paper, a complex contaminated soil on the surface with Pb and As in a smelter in Henan was taken as the research object. By applying different DC voltages, electrokinetic remediation was carried out. Then based on the mobility and form changes, the restoration effect was evaluated. During the restoration process, we studied the current change, Pb/As migration law, soil moisture content, electrical conductivity, pH value, and Pb/As speciation transformation. The results showed that the change of applied DC voltage had a stronger effect on the migration of Pb in the soil, but a weaker effect on the migration of As. When the applied DC voltage was 10 V, As content in the cathode region of the sample soil was reduced to 43.18 mg/kg; and when the applied DC voltage was 30 V, the Pb content in the cathode region was reduced to 334 mg/kg. The operation of applying low-voltage current first and then high-voltage current was more effective to improve the electrokinetic remediation effect of Pb and As compound contaminated soil. In the restored soil, the proportion of weak acid state of Pb and As decreased, and the proportion of reducible state increased. The content of Pb and As in soil was lower than the screening value for construction land Class Ⅰ in GB 36600—2018.
2022, 40(8): 136-142.
doi: 10.13205/j.hjgc.202208019
Abstract:
Based on the stabilizing effect of nano-TiO2 dioxide on soil arsenic, using self-made modified nano-TiO2 (TiO2/AC and Fe-TiO2/AC) as the test material, the effects of modified nano-TiO2 on the speciation of As, soil pH, nutrients and enzymatic activities were studied through indoor simulation experiments. The results showed that: with the action of TiO2/AC and Fe-TiO2/AC, the non-specific adsorption state and obligate adsorption state of arsenic with strong activity in soil decreased by 1.1%~6.3%, 1.8%~9.5% and 2.1%~6.9%, 10.1%~18%, respectively. While the bound and residual states of inert arsenic amorphous and weakly crystalline hydrated iron-aluminum oxides increased by 1.0%~14.8%, 2.2%~10.5% and 3.7%~16.9%, 6.5%~16.7%, respectively. With the action of TiO2/AC and Fe-TiO2/AC, the soil pH increased by 0.05~0.13 and 0.20~0.35, respectively. The increase rates of available potassium were 17.2%~32.2% and 28.7%~29.5%, and the decrease rates of available nitrogen content were 25.1%~37.8% and 23.5%~44.6%, respectively. Two kinds of modified nano-TiO2 all had activating effect on soil neutral and alkaline phosphatase activity. TiO2/AC had an inhibiting effect on activity of urease and catalase, and after iron modification, its inhibiting effect tended to be weaker. The soil catalase activity increased by 19.5% compared with the control when the application amount was 0.3%; the soil urease activity decreased by 63.0%~76.6% after applying TiO2/AC, but under the action of 0.4% Fe-TiO2/AC, the soil urease activity decreased by 63.0%~76.6%. Urease activity increased by 5.8% compared with the control. In short, the modified nano-TiO2 transformed arsenic in soil from active states to inert states, and the influence on the soil properties could be controlled by iron modification.
Based on the stabilizing effect of nano-TiO2 dioxide on soil arsenic, using self-made modified nano-TiO2 (TiO2/AC and Fe-TiO2/AC) as the test material, the effects of modified nano-TiO2 on the speciation of As, soil pH, nutrients and enzymatic activities were studied through indoor simulation experiments. The results showed that: with the action of TiO2/AC and Fe-TiO2/AC, the non-specific adsorption state and obligate adsorption state of arsenic with strong activity in soil decreased by 1.1%~6.3%, 1.8%~9.5% and 2.1%~6.9%, 10.1%~18%, respectively. While the bound and residual states of inert arsenic amorphous and weakly crystalline hydrated iron-aluminum oxides increased by 1.0%~14.8%, 2.2%~10.5% and 3.7%~16.9%, 6.5%~16.7%, respectively. With the action of TiO2/AC and Fe-TiO2/AC, the soil pH increased by 0.05~0.13 and 0.20~0.35, respectively. The increase rates of available potassium were 17.2%~32.2% and 28.7%~29.5%, and the decrease rates of available nitrogen content were 25.1%~37.8% and 23.5%~44.6%, respectively. Two kinds of modified nano-TiO2 all had activating effect on soil neutral and alkaline phosphatase activity. TiO2/AC had an inhibiting effect on activity of urease and catalase, and after iron modification, its inhibiting effect tended to be weaker. The soil catalase activity increased by 19.5% compared with the control when the application amount was 0.3%; the soil urease activity decreased by 63.0%~76.6% after applying TiO2/AC, but under the action of 0.4% Fe-TiO2/AC, the soil urease activity decreased by 63.0%~76.6%. Urease activity increased by 5.8% compared with the control. In short, the modified nano-TiO2 transformed arsenic in soil from active states to inert states, and the influence on the soil properties could be controlled by iron modification.
2022, 40(8): 143-149.
doi: 10.13205/j.hjgc.202208020
Abstract:
The interception facility is an important and frequently-used measure for combined sewer overflows (CSOs) control in city-scale drainage systems. By combining the stormwater management model (SWMM) with the multi-objective genetic algorithm (NSGA-Ⅲ), the optimal design problems of interception and storage facilities were solved. The method took the interception efficiency, construction cost, and the number of pump startup/shutoff times as the optimization objectives of the model, and achieved multi-objective optimization of the interception and storage facility scale. Through object-oriented recoding of SWMM, multi-threaded calculation and fast data exchange between SWMM and NSGA-Ⅲ modules were realized, frequent file operations were avoided, and the solution efficiency was increased to 16 times that of single-threaded calculation. The method was used to optimize the design of terminal flow interception and storage facilities for a combined drainage system in Wuhan. The results indicated the construction cost of the optimized design was reduced to 60% of the original design, and it had more advantages in the aspects of interception efficiency and storage pool volume.
The interception facility is an important and frequently-used measure for combined sewer overflows (CSOs) control in city-scale drainage systems. By combining the stormwater management model (SWMM) with the multi-objective genetic algorithm (NSGA-Ⅲ), the optimal design problems of interception and storage facilities were solved. The method took the interception efficiency, construction cost, and the number of pump startup/shutoff times as the optimization objectives of the model, and achieved multi-objective optimization of the interception and storage facility scale. Through object-oriented recoding of SWMM, multi-threaded calculation and fast data exchange between SWMM and NSGA-Ⅲ modules were realized, frequent file operations were avoided, and the solution efficiency was increased to 16 times that of single-threaded calculation. The method was used to optimize the design of terminal flow interception and storage facilities for a combined drainage system in Wuhan. The results indicated the construction cost of the optimized design was reduced to 60% of the original design, and it had more advantages in the aspects of interception efficiency and storage pool volume.
2022, 40(8): 150-158,61.
doi: 10.13205/j.hjgc.202208021
Abstract:
Spectral characterization combined with multivariate statistical method was used to monitor and analyze the variation of organic matter concentration and spectral indexes in the inlet and outlet water of each treatment unit in the Yanlong project and Tongyu project in Yancheng. The results showed that the content of dissolved oxygen in the raw water of the Tongyu River and the Mangshe River was lower than that of the class Ⅲ in surface water quality standards in summer. In terms of organic concentration, a(254) was higher in raw water of Yanlong Lake, while CODMn and BOD5 were higher in raw water of Tongyu River. The removal rates of CODMn, BOD5, a(254) and a(355) in the pretreatment engineering of Yanlong Lake and Tongyu River were 4.19%, 37.50%, 1.55% and 10.31%, 23.49%, 24.88%, respectively. From the perspective of molecular structure, the pretreatment unit of Yanlong project and high-density sedimentation unit of Tongyu project had the most obvious changes on DOM, resulting in a decrease in DOM’s concentration and molecular weight, and a rise in the degree of polymerization of carbon atoms in benzene ring. The difference analysis showed that SR and E465/E665 had a significant positive correlation with A2/A1 and A3/A1 at 0.01 level, while a(355) had a significant negative correlation with E250/E365 at 0.01 level. The research results provide a theoretical basis for optimizing the operation of micro-polluted water source pretreatment engineering and safety ensuring of urban drinking water supply.
Spectral characterization combined with multivariate statistical method was used to monitor and analyze the variation of organic matter concentration and spectral indexes in the inlet and outlet water of each treatment unit in the Yanlong project and Tongyu project in Yancheng. The results showed that the content of dissolved oxygen in the raw water of the Tongyu River and the Mangshe River was lower than that of the class Ⅲ in surface water quality standards in summer. In terms of organic concentration, a(254) was higher in raw water of Yanlong Lake, while CODMn and BOD5 were higher in raw water of Tongyu River. The removal rates of CODMn, BOD5, a(254) and a(355) in the pretreatment engineering of Yanlong Lake and Tongyu River were 4.19%, 37.50%, 1.55% and 10.31%, 23.49%, 24.88%, respectively. From the perspective of molecular structure, the pretreatment unit of Yanlong project and high-density sedimentation unit of Tongyu project had the most obvious changes on DOM, resulting in a decrease in DOM’s concentration and molecular weight, and a rise in the degree of polymerization of carbon atoms in benzene ring. The difference analysis showed that SR and E465/E665 had a significant positive correlation with A2/A1 and A3/A1 at 0.01 level, while a(355) had a significant negative correlation with E250/E365 at 0.01 level. The research results provide a theoretical basis for optimizing the operation of micro-polluted water source pretreatment engineering and safety ensuring of urban drinking water supply.
2022, 40(8): 159-163,142.
doi: 10.13205/j.hjgc.202208022
Abstract:
Aerobic fermentation (composting) technology is an important method to achieve the harmless transformation of organic solid waste, but the traditional composting technology has a long fermentation cycle, a large area of land, and a poor operating environment, which limits its wide application. The purpose of this paper was to research and develop the enhanced aerobic fermentation process of organic waste, and systematical study the influence of various parameters on the aerobic fermentation process of organic waste by screening the key controllable factors of enhanced composting, such as environmental temperature, microbial inoculation, supplementary feeding, stirring and ventilation frequency, etc. The results showed that the composting cycle could be shortened, and the fermentation efficiency could be improved by increasing the ambient temperature, controlling the stirring and ventilation frequency reasonably, and inoculating strains and adding auxiliary materials. This result has a guiding significance for the development of mechanical enhanced rapid composting technology.
Aerobic fermentation (composting) technology is an important method to achieve the harmless transformation of organic solid waste, but the traditional composting technology has a long fermentation cycle, a large area of land, and a poor operating environment, which limits its wide application. The purpose of this paper was to research and develop the enhanced aerobic fermentation process of organic waste, and systematical study the influence of various parameters on the aerobic fermentation process of organic waste by screening the key controllable factors of enhanced composting, such as environmental temperature, microbial inoculation, supplementary feeding, stirring and ventilation frequency, etc. The results showed that the composting cycle could be shortened, and the fermentation efficiency could be improved by increasing the ambient temperature, controlling the stirring and ventilation frequency reasonably, and inoculating strains and adding auxiliary materials. This result has a guiding significance for the development of mechanical enhanced rapid composting technology.
2022, 40(8): 164-170.
doi: 10.13205/j.hjgc.202208023
Abstract:
Given the problems of acid fluorine-containing wastewater from large abandoned graphite mines left over from history, such as large volume, difficult dosing of deep water, low reaction efficiency, serious pollution and less treatment experience, we explored its controlling mode, taking Yueshi Mine wastewater in Nanshu Town, Laixi in Shandong Province as the research object. Based on the laboratory wastewater treatment test, the remediation agent was optimized. Based on the field investigation, through the construction of a three-dimensional mine model and hydrodynamic model calculation, the effect of water displacement under different operating conditions was simulated, and the optimal technological scheme was determined. Finally, the scheme of compound remediation agent with in-situ water exchange was put forward. After treatment, the pH value of mine wastewater reached about 7, and the fluoride concentration dropped below 30 mg/L, reaching the wastewater treatment goal. The water pollution remediation technology system established in the treatment process provide a reference for large-scale acid fluoride wastewater treatment in other areas.
Given the problems of acid fluorine-containing wastewater from large abandoned graphite mines left over from history, such as large volume, difficult dosing of deep water, low reaction efficiency, serious pollution and less treatment experience, we explored its controlling mode, taking Yueshi Mine wastewater in Nanshu Town, Laixi in Shandong Province as the research object. Based on the laboratory wastewater treatment test, the remediation agent was optimized. Based on the field investigation, through the construction of a three-dimensional mine model and hydrodynamic model calculation, the effect of water displacement under different operating conditions was simulated, and the optimal technological scheme was determined. Finally, the scheme of compound remediation agent with in-situ water exchange was put forward. After treatment, the pH value of mine wastewater reached about 7, and the fluoride concentration dropped below 30 mg/L, reaching the wastewater treatment goal. The water pollution remediation technology system established in the treatment process provide a reference for large-scale acid fluoride wastewater treatment in other areas.
2022, 40(8): 171-177.
doi: 10.13205/j.hjgc.202208024
Abstract:
In this paper, new pumice was prepared with waste glass and cement blocks, and its adsorption effect and competition effect on Cr3+, As3+, Pb2+, Cu2+ and Zn2+ were studied. The adsorption kinetics model, adsorption isotherm model and Fourier infrared spectroscopy were used to study the removal of heavy metals, and the recycling performance of pumice was investigated. The results showed that the adsorption capacity of pumice for Cr3+, As3+, Pb2+, Cu2+ and Zn2+ were 64, 110, 79, 161, 161 μg/mg, respectively. The adsorption of heavy metals was mainly related to the functional groups and chemical bonds on the surface. The adsorption process fitted well with the quasi-second-order kinetic model, and the adsorption isotherms was well simulated by Langmuir model and Freundlich model. When the five heavy metals coexisted, the adsorption competition reflected the adsorption preference by pumice, and the removal rate of the heavy metal ions followed the order of Cr3+>Cu2+>Zn2+>As3+>Pb2+. After six cycles, the removal rate of five heavy metals was still above 50%, indicating that the new pumice had good adsorption and recycling performance. The pumice adsorbent prepared with construction waste conformed to the concept of Using Waste to Treat Waste and had broad application prospects.
In this paper, new pumice was prepared with waste glass and cement blocks, and its adsorption effect and competition effect on Cr3+, As3+, Pb2+, Cu2+ and Zn2+ were studied. The adsorption kinetics model, adsorption isotherm model and Fourier infrared spectroscopy were used to study the removal of heavy metals, and the recycling performance of pumice was investigated. The results showed that the adsorption capacity of pumice for Cr3+, As3+, Pb2+, Cu2+ and Zn2+ were 64, 110, 79, 161, 161 μg/mg, respectively. The adsorption of heavy metals was mainly related to the functional groups and chemical bonds on the surface. The adsorption process fitted well with the quasi-second-order kinetic model, and the adsorption isotherms was well simulated by Langmuir model and Freundlich model. When the five heavy metals coexisted, the adsorption competition reflected the adsorption preference by pumice, and the removal rate of the heavy metal ions followed the order of Cr3+>Cu2+>Zn2+>As3+>Pb2+. After six cycles, the removal rate of five heavy metals was still above 50%, indicating that the new pumice had good adsorption and recycling performance. The pumice adsorbent prepared with construction waste conformed to the concept of Using Waste to Treat Waste and had broad application prospects.
2022, 40(8): 178-184.
doi: 10.13205/j.hjgc.202208025
Abstract:
The research and development of herbicide-degrading inoculants is an effective way to solve herbicide residues in a green and low-carbon strategy. In this study, coconut bran carrier (corn flour, coconut bran, kaolin, white sugar) and sodium alginate carrier (sodium alginate, kaolin, glycerin) were used to prepare Penicillium agents. The results showed that the coconut bran carriers were powdery, finely crushed and soft, and were brown or white-brown, while the sodium alginate beads carrier was round granular, hard, and white or yellowish. After one month’s storage, the minimum number of effective viable fungi in both agents was 2.7×1010/g and 1.7×1010/g, higher than the requirements in the microbial inoculum standard of the Microbial Inoculants in Agriculture (GB 20287—2006). The number of molds and the total number of bacteria in the sodium alginate beads carrier was lower than that of the carrier prepared from coconut bran, and the hybrid bacteria rate was 14.3%~17.3%. The water content of coconut bran carrier was generally low, ranging from 2.88%~5.27%, and the water content of sodium alginate beads carrier was 11.53%~13.96%, which was lower than 35.0% (powder) and 20.0% (granule) in GB 20287—2006. The fineness mass fraction in both carriers exceeded 90%, higher than 80.0% in GB 20287—2006. Based on the national standard requirement of the pH value between 5.5~8.5, the best mixing ratio of corn flour, coconut bran, kaolin and white sugar in the coconut bran carrier was 10∶8∶6∶3 (by mass), wherever the sodium alginate beads carrier was: sodium alginate 2% (W/V), kaolin 1% (W/V), glycerin 60% (W/W). Comparing the two carriers by the effective number of viable microbial and hybrid bacteria, the coconut peat carrier was the relatively feasible carrier for herbicide degrading agents. The findings provide good technical support for the prevention and control of herbicide non-point source pollution.
The research and development of herbicide-degrading inoculants is an effective way to solve herbicide residues in a green and low-carbon strategy. In this study, coconut bran carrier (corn flour, coconut bran, kaolin, white sugar) and sodium alginate carrier (sodium alginate, kaolin, glycerin) were used to prepare Penicillium agents. The results showed that the coconut bran carriers were powdery, finely crushed and soft, and were brown or white-brown, while the sodium alginate beads carrier was round granular, hard, and white or yellowish. After one month’s storage, the minimum number of effective viable fungi in both agents was 2.7×1010/g and 1.7×1010/g, higher than the requirements in the microbial inoculum standard of the Microbial Inoculants in Agriculture (GB 20287—2006). The number of molds and the total number of bacteria in the sodium alginate beads carrier was lower than that of the carrier prepared from coconut bran, and the hybrid bacteria rate was 14.3%~17.3%. The water content of coconut bran carrier was generally low, ranging from 2.88%~5.27%, and the water content of sodium alginate beads carrier was 11.53%~13.96%, which was lower than 35.0% (powder) and 20.0% (granule) in GB 20287—2006. The fineness mass fraction in both carriers exceeded 90%, higher than 80.0% in GB 20287—2006. Based on the national standard requirement of the pH value between 5.5~8.5, the best mixing ratio of corn flour, coconut bran, kaolin and white sugar in the coconut bran carrier was 10∶8∶6∶3 (by mass), wherever the sodium alginate beads carrier was: sodium alginate 2% (W/V), kaolin 1% (W/V), glycerin 60% (W/W). Comparing the two carriers by the effective number of viable microbial and hybrid bacteria, the coconut peat carrier was the relatively feasible carrier for herbicide degrading agents. The findings provide good technical support for the prevention and control of herbicide non-point source pollution.
2022, 40(8): 185-190.
doi: 10.13205/j.hjgc.202208026
Abstract:
This paper evaluates the environmental impact of the recycling production process of hydrogen desulfurization waste metal catalyst, based on the life cycle assessment(LCA), divides the whole recycling production process into six stages, selects 12 key environmental impact types, establishes material input and emission list, and conducts the model building and calculation based on eBalance software. The results showed that the total environmental impact of recovering 1 ton of spent catalyst is 1.11E-08, and the potential value of the GWP(potential value of the global warming effect) is the largest environmental impact contribution type in the process of recovering spent catalyst. The environmental impact contribution of the roasting stage is the largest, followed by the cobalt nickel extraction stage, concentration evaporation stage and then molybdenum vanadium extraction stage, while the environmental impact contribution of the pretreatment stage and transportation stage is very small. The energy alternative is proposed based on the life cycle evaluation analysis, and the environmental impact of the clean energy alternatives is 4.98E-09, reduced by 55.16% from the environmental impact of recycling process.
This paper evaluates the environmental impact of the recycling production process of hydrogen desulfurization waste metal catalyst, based on the life cycle assessment(LCA), divides the whole recycling production process into six stages, selects 12 key environmental impact types, establishes material input and emission list, and conducts the model building and calculation based on eBalance software. The results showed that the total environmental impact of recovering 1 ton of spent catalyst is 1.11E-08, and the potential value of the GWP(potential value of the global warming effect) is the largest environmental impact contribution type in the process of recovering spent catalyst. The environmental impact contribution of the roasting stage is the largest, followed by the cobalt nickel extraction stage, concentration evaporation stage and then molybdenum vanadium extraction stage, while the environmental impact contribution of the pretreatment stage and transportation stage is very small. The energy alternative is proposed based on the life cycle evaluation analysis, and the environmental impact of the clean energy alternatives is 4.98E-09, reduced by 55.16% from the environmental impact of recycling process.
2022, 40(8): 191-196,149.
doi: 10.13205/j.hjgc.202208027
Abstract:
Taking Shangqiu in Henan province as the research object, the pollution characteristics of eight heavy metals Cr, Ni, Cu, Zn, As, Pb, Cd and Hg were analyzed. The degree of pollution caused by heavy metals in the recycled products and their raw materials in Shangqiu was determined through the enrichment factor method and toxicity-leaching test, and the potential ecological risk was also evaluated. The results showed that, in raw material of the recycled products, Hg was the main pollution factor, followed by Cr and Ni, and all of them contributed greatly to the leaching rate of heavy metals and the potential ecological risk index. They might be affected by human activities and should be stored in shelter from the rain. In the recycled products, Hg was the main pollution factor, followed by Ni. The ecological risk of the recycled products was lower than that of the raw materials of the recycled products, indicating that this recycling approach was conducive to reduce the potential ecological risk of heavy metals in construction waste. Therefore, the recycled products have a good application prospect.
Taking Shangqiu in Henan province as the research object, the pollution characteristics of eight heavy metals Cr, Ni, Cu, Zn, As, Pb, Cd and Hg were analyzed. The degree of pollution caused by heavy metals in the recycled products and their raw materials in Shangqiu was determined through the enrichment factor method and toxicity-leaching test, and the potential ecological risk was also evaluated. The results showed that, in raw material of the recycled products, Hg was the main pollution factor, followed by Cr and Ni, and all of them contributed greatly to the leaching rate of heavy metals and the potential ecological risk index. They might be affected by human activities and should be stored in shelter from the rain. In the recycled products, Hg was the main pollution factor, followed by Ni. The ecological risk of the recycled products was lower than that of the raw materials of the recycled products, indicating that this recycling approach was conducive to reduce the potential ecological risk of heavy metals in construction waste. Therefore, the recycled products have a good application prospect.
2022, 40(8): 197-205,101.
doi: 10.13205/j.hjgc.202208028
Abstract:
Concrete is the most widely used building material in construction engineering and coastal engineering. The addition of mineral admixtures as auxiliary cementitious materials to concrete can not only improve environmental benefits through waste utilization, certain mineral admixtures can also improve certain properties of concrete. To objectively evaluate the comprehensive performance of mineral admixture concrete’s safety, durability and environmental friendliness,a comprehensive evaluation method of mineral admixture concrete was proposed. First, based on the life cycle assessment theory of environmental impact, environmental impact lists of five mineral admixtures including fly ash, granulated blast furnace slag powder, coal gangue powder, red mud, and glass powder were established through real-world data and investigation. And the calculation methods of mineral admixture concrete for seven environmental impact indicators were established. The social willingness to pay method was adopted to uniformly monetize different environmental impact indicators under the framework of environmental protection tax and resource tax. Combined with the strength and durability indicators of concrete, a comprehensive evaluation method for the performance and environmental benefits of mineral admixture concrete was proposed. This method can provide a quantitative evaluation basis for the development of eco-friendly high-performance concrete.
Concrete is the most widely used building material in construction engineering and coastal engineering. The addition of mineral admixtures as auxiliary cementitious materials to concrete can not only improve environmental benefits through waste utilization, certain mineral admixtures can also improve certain properties of concrete. To objectively evaluate the comprehensive performance of mineral admixture concrete’s safety, durability and environmental friendliness,a comprehensive evaluation method of mineral admixture concrete was proposed. First, based on the life cycle assessment theory of environmental impact, environmental impact lists of five mineral admixtures including fly ash, granulated blast furnace slag powder, coal gangue powder, red mud, and glass powder were established through real-world data and investigation. And the calculation methods of mineral admixture concrete for seven environmental impact indicators were established. The social willingness to pay method was adopted to uniformly monetize different environmental impact indicators under the framework of environmental protection tax and resource tax. Combined with the strength and durability indicators of concrete, a comprehensive evaluation method for the performance and environmental benefits of mineral admixture concrete was proposed. This method can provide a quantitative evaluation basis for the development of eco-friendly high-performance concrete.
2022, 40(8): 206-212.
doi: 10.13205/j.hjgc.202208029
Abstract:
Geosynthetics used in different types of green stormwater infrastructure (GSI) mainly play the role of filtration, isolation, protection, seepage prevention and drainage, so as to improve the capacity of infiltration, storage, purification, utilization, discharge and etc. of the facilities. In this paper, the main functions, requirements, performance and applicable conditions of geosynthetics in different GSI are summarized. The parameter requirements and improvement effects of geosynthetics applied to typical GSI, such as infiltration facilities and permeable pavement are emphatically analyzed. Suggestions on the prevention of clogging and maintenance of geotextiles, the selection of geosynthetics in GSI and the application direction of new materials are proposed.
Geosynthetics used in different types of green stormwater infrastructure (GSI) mainly play the role of filtration, isolation, protection, seepage prevention and drainage, so as to improve the capacity of infiltration, storage, purification, utilization, discharge and etc. of the facilities. In this paper, the main functions, requirements, performance and applicable conditions of geosynthetics in different GSI are summarized. The parameter requirements and improvement effects of geosynthetics applied to typical GSI, such as infiltration facilities and permeable pavement are emphatically analyzed. Suggestions on the prevention of clogging and maintenance of geotextiles, the selection of geosynthetics in GSI and the application direction of new materials are proposed.
2022, 40(8): 213-219,212.
doi: 10.13205/j.hjgc.202208030
Abstract:
Volatile organic compounds which are usually complex and highly volatile, are difficult to completely remove by traditional atmospheric treatment technology. Low-temperature plasma technology can effectively degrade volatile organic compounds by using strong oxidizing substances such as O·,·OH, N· and O3. With the development of industry, the emission and pollutant composition of volatile organic compounds continue to increase, which widely exists in coal-fired emission, pharmaceutical manufacturing emission and automobile exhaust emission. In this paper, firstly, the reaction mechanism of VOCs degradation by low-temperature plasma alone was described. Then the synergy between plasma and catalyst was briefly described, and the influence of catalyst position on degradation efficiency was analysed. The synergistic effects of different catalysts were analysed, mainly including noble metal catalysts, composite metal catalysts, transition metal catalysts, perovskite catalysts and photocatalysts. The degradation mechanism of these catalysts for VOCs was deeply analysed, and the degradation effects and influencing factors of these catalysts for VOCs were summarized. Finally, the existing problems and future research and development direction of low-temperature plasma synergistic catalytic degradation of VOCs were put forward, which laid a theoretical foundation for practical industrial waste gas treatment.
Volatile organic compounds which are usually complex and highly volatile, are difficult to completely remove by traditional atmospheric treatment technology. Low-temperature plasma technology can effectively degrade volatile organic compounds by using strong oxidizing substances such as O·,·OH, N· and O3. With the development of industry, the emission and pollutant composition of volatile organic compounds continue to increase, which widely exists in coal-fired emission, pharmaceutical manufacturing emission and automobile exhaust emission. In this paper, firstly, the reaction mechanism of VOCs degradation by low-temperature plasma alone was described. Then the synergy between plasma and catalyst was briefly described, and the influence of catalyst position on degradation efficiency was analysed. The synergistic effects of different catalysts were analysed, mainly including noble metal catalysts, composite metal catalysts, transition metal catalysts, perovskite catalysts and photocatalysts. The degradation mechanism of these catalysts for VOCs was deeply analysed, and the degradation effects and influencing factors of these catalysts for VOCs were summarized. Finally, the existing problems and future research and development direction of low-temperature plasma synergistic catalytic degradation of VOCs were put forward, which laid a theoretical foundation for practical industrial waste gas treatment.
2022, 40(8): 220-224.
doi: 10.13205/j.hjgc.202208031
Abstract:
Steel slag is a solid waste discharged from the steelmaking process. It has the characteristics of large annual output, high temperature, complex chemical composition, high hardness and poor stability. Under the carbon peaking and carbon neutrality goals, its treatment and resource utilization attracted attention again. In view of the characteristics of steel slag, this article summarizes the domestic and foreign steel slag treatment and utilization, and points out the problems in the existing treatment technologies and resource utilization methods. The resource utilization of steel slag under the carbon peaking and carbon neutrality goals is discussed, and we believe that steel slag waste heat recovery, molten steel slag reduction modification, and CO2 capture are the focus of the future steel slag treatment.
Steel slag is a solid waste discharged from the steelmaking process. It has the characteristics of large annual output, high temperature, complex chemical composition, high hardness and poor stability. Under the carbon peaking and carbon neutrality goals, its treatment and resource utilization attracted attention again. In view of the characteristics of steel slag, this article summarizes the domestic and foreign steel slag treatment and utilization, and points out the problems in the existing treatment technologies and resource utilization methods. The resource utilization of steel slag under the carbon peaking and carbon neutrality goals is discussed, and we believe that steel slag waste heat recovery, molten steel slag reduction modification, and CO2 capture are the focus of the future steel slag treatment.
2022, 40(8): 231-238.
doi: 10.13205/j.hjgc.202208033
Abstract:
The soil remediation industry in China is about to usher in explosive growth, and the market scale will exceed a trillion in the future. And soil remediation industry is with the most development potential in the environmental protection industry. Carbon emissions will affect the world climate change and change the human living environment. China proposed the carbon peaking and carbon neutrality goals, which aimed to optimize the energy structure and maintain the global carbon dioxide balance. Carbon emissions in the soil remediation industry will gradually increase with the development of the soil remediation market, so scientific carbon emission reduction measures are essential in the near future. This study predicted the time point of carbon peaking and carbon neutrality in the soil remediation industry, analyzed the carbon emission in the soil remediation industry, and put forward the path to achieve the carbon peaking and carbon neutrality goals.
The soil remediation industry in China is about to usher in explosive growth, and the market scale will exceed a trillion in the future. And soil remediation industry is with the most development potential in the environmental protection industry. Carbon emissions will affect the world climate change and change the human living environment. China proposed the carbon peaking and carbon neutrality goals, which aimed to optimize the energy structure and maintain the global carbon dioxide balance. Carbon emissions in the soil remediation industry will gradually increase with the development of the soil remediation market, so scientific carbon emission reduction measures are essential in the near future. This study predicted the time point of carbon peaking and carbon neutrality in the soil remediation industry, analyzed the carbon emission in the soil remediation industry, and put forward the path to achieve the carbon peaking and carbon neutrality goals.
