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2021 Vol. 39, No. 2
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2021, 39(2): 1-9.
doi: 10.13205/j.hjgc.202102001
Abstract:
Adsorption is one of the most important methods for the removal of typical pharmaceutical and personal care products (PPCPs) in wastewater. In this study, the removal rate, adsorption capacity, and mechanisms of adsorption of typical PPCPs in various adsorbents was summarized, and the influencing factors on their adsorption of PPCPs were also discussed. In general, some limitations were associated with the existing studies, and in particular the mechanisms of PPCP adsorption was still unclear. It was found that most of the existing studies were mainly focused on reporting the removal efficiency of PPCPs by different adsorbents. Future studies should give priority on the mass transfer process, mechanism exploration and control steps of PPCP adsorption by different adsorbents.
Adsorption is one of the most important methods for the removal of typical pharmaceutical and personal care products (PPCPs) in wastewater. In this study, the removal rate, adsorption capacity, and mechanisms of adsorption of typical PPCPs in various adsorbents was summarized, and the influencing factors on their adsorption of PPCPs were also discussed. In general, some limitations were associated with the existing studies, and in particular the mechanisms of PPCP adsorption was still unclear. It was found that most of the existing studies were mainly focused on reporting the removal efficiency of PPCPs by different adsorbents. Future studies should give priority on the mass transfer process, mechanism exploration and control steps of PPCP adsorption by different adsorbents.
2021, 39(2): 10-15.
doi: 10.13205/j.hjgc.202102002
Abstract:
The sol-gel method was used to prepare the Fe/Cu/zeolite catalyst for heterogeneous Fenton oxidation. The reaction conditions of catalytic degradation of benzotriazole in water at neutral pH were optimized, and the reusability of the material was investigated. Finally, the mechanism of catalytic oxidation degradation of BTA was discussed. The results showed that Fe and Cu nanoparticles in the catalyst were uniformly distributed on the surface of the zeolite particles, and the main components were Fe2O3, Fe3O4 and CuO. Under neutral pH conditions, the highest degradation rate of benzotriazole was achieved at the concentration of H2O2 0.08 mol/L, the catalyst dosage 0.41 g/L and the reaction time 43.6 min. During the catalytic degradation process, Fe and Cu participate in the Fenton reaction to generate ·OH radicals, and achieve efficient removal of pollutants.
The sol-gel method was used to prepare the Fe/Cu/zeolite catalyst for heterogeneous Fenton oxidation. The reaction conditions of catalytic degradation of benzotriazole in water at neutral pH were optimized, and the reusability of the material was investigated. Finally, the mechanism of catalytic oxidation degradation of BTA was discussed. The results showed that Fe and Cu nanoparticles in the catalyst were uniformly distributed on the surface of the zeolite particles, and the main components were Fe2O3, Fe3O4 and CuO. Under neutral pH conditions, the highest degradation rate of benzotriazole was achieved at the concentration of H2O2 0.08 mol/L, the catalyst dosage 0.41 g/L and the reaction time 43.6 min. During the catalytic degradation process, Fe and Cu participate in the Fenton reaction to generate ·OH radicals, and achieve efficient removal of pollutants.
2021, 39(2): 16-20,26.
doi: 10.13205/j.hjgc.202102003
Abstract:
As China vigorously promotes the implementation of pollutant discharge permit system nationwide, emission permit limits become increasingly important as the key point of pollutant discharge permit.This paper focused on the comparison of the practice and research status of the pollution permit limit approval technology in China and the United States from three aspects:verification methods based on legal basis, technologies and water quality. Comparing the characteristics and experiences between the US and China technology for the verification of emission permit limits, this paper summarized the problems existing in China's corresponding technologies. Such as the imperfect laws and regulations, the incomplete technical guidance documents, low accuracy of technology-based technology for the verification of emission permit limits, and lack of technology for the verification of emission permit limits based on water quality. Finally, it provided suggestions for the improvement of emission permit limit verification technology in China.
As China vigorously promotes the implementation of pollutant discharge permit system nationwide, emission permit limits become increasingly important as the key point of pollutant discharge permit.This paper focused on the comparison of the practice and research status of the pollution permit limit approval technology in China and the United States from three aspects:verification methods based on legal basis, technologies and water quality. Comparing the characteristics and experiences between the US and China technology for the verification of emission permit limits, this paper summarized the problems existing in China's corresponding technologies. Such as the imperfect laws and regulations, the incomplete technical guidance documents, low accuracy of technology-based technology for the verification of emission permit limits, and lack of technology for the verification of emission permit limits based on water quality. Finally, it provided suggestions for the improvement of emission permit limit verification technology in China.
2021, 39(2): 21-26.
doi: 10.13205/j.hjgc.202102004
Abstract:
In this study, a heterotrophic nitrification-aerobic denitrifying strain named GNR was isolated from swine wastewater. It was identified as a new strain of genus Acinetobacter through morphological and phylogenetic analysis. The optimal heterotrophic nitrification and aerobic denitrification conditions were investigated as the carbon source of trisodium citrate, C/N ratio of 10:1, initial pH of 8.0 and 6.0, respectively. The maximum removal efficiencies of ammonia and nitrate nitrogen with initial concentration of 50.0 mg/L both reached over 99.0% by strain GNR, after 30℃, 125 r/min shaking cultivation for 72 h. Under the optimal condition, the COD and ammonia removal efficiencies in diluted swine wastewater treatment reached 129, 73 mg/(L·g), respectively. The experimental results indicated that strain GNR had good application potential in wastewater denitrification.
In this study, a heterotrophic nitrification-aerobic denitrifying strain named GNR was isolated from swine wastewater. It was identified as a new strain of genus Acinetobacter through morphological and phylogenetic analysis. The optimal heterotrophic nitrification and aerobic denitrification conditions were investigated as the carbon source of trisodium citrate, C/N ratio of 10:1, initial pH of 8.0 and 6.0, respectively. The maximum removal efficiencies of ammonia and nitrate nitrogen with initial concentration of 50.0 mg/L both reached over 99.0% by strain GNR, after 30℃, 125 r/min shaking cultivation for 72 h. Under the optimal condition, the COD and ammonia removal efficiencies in diluted swine wastewater treatment reached 129, 73 mg/(L·g), respectively. The experimental results indicated that strain GNR had good application potential in wastewater denitrification.
2021, 39(2): 27-32,40.
doi: 10.13205/j.hjgc.202102005
Abstract:
The ability of HN-AD bacteria to simultaneous nitrification and denitrification caused widespread concern in biological wastewater treatment. In order to investigate the application potential of HN-AD bacteria in ammonia-rich wastewater, the HN-AD bacteria Alcaligenes faecalis WT14 was isolated from the substrate of constructed wetland sediment. The nitrogen removal characteristics of this strain were studied under aerobic conditions, and the effect of the interaction between the removal potential of high ammonia wastewater and environmental factors on its nitrogen removal efficiency was evaluated. The strain WT14 exhibited excellent HN-AD performance and high ammonia tolerance. It could remove 98.9% of NO3--N and 92.7% of TOC under aerobic conditions, and no NO2--N accumulation took place in the whole course. At the same time, the strain WT14 treated high ammonia (2000 mg/L) wastewater with a free ammonia concentration of 1084.6 mg/L and removed about 43% NH4+-N without accumulation of NO3--N. The results of response surface methodology showed that the optimal conditions for denitrification were as follows:20.6℃, 113.5 r/min, C/N of 10.8, and pH of 8.4. Overall, the strain WT14 has good potential for ammonia-rich wastewater treatment.
The ability of HN-AD bacteria to simultaneous nitrification and denitrification caused widespread concern in biological wastewater treatment. In order to investigate the application potential of HN-AD bacteria in ammonia-rich wastewater, the HN-AD bacteria Alcaligenes faecalis WT14 was isolated from the substrate of constructed wetland sediment. The nitrogen removal characteristics of this strain were studied under aerobic conditions, and the effect of the interaction between the removal potential of high ammonia wastewater and environmental factors on its nitrogen removal efficiency was evaluated. The strain WT14 exhibited excellent HN-AD performance and high ammonia tolerance. It could remove 98.9% of NO3--N and 92.7% of TOC under aerobic conditions, and no NO2--N accumulation took place in the whole course. At the same time, the strain WT14 treated high ammonia (2000 mg/L) wastewater with a free ammonia concentration of 1084.6 mg/L and removed about 43% NH4+-N without accumulation of NO3--N. The results of response surface methodology showed that the optimal conditions for denitrification were as follows:20.6℃, 113.5 r/min, C/N of 10.8, and pH of 8.4. Overall, the strain WT14 has good potential for ammonia-rich wastewater treatment.
2021, 39(2): 33-40.
doi: 10.13205/j.hjgc.202102006
Abstract:
As one of the most common pollutants in groundwater, excessive arsenic intake will seriously threaten human health. The kinetics, isotherm and thermodynamics in the adsorption process were analyzed, and the effects of pH and inorganic anions on the adsorption of As(Ⅲ) in water by natural pyrrhotite were studied. It was found that adsorption of As(Ⅲ) by pyrrhotite reached equilibrium in 48 h. Adsorption processes followed the Langmuir isothermal model, in the range of 1~200 mg/L for initial concentration, and the saturated adsorption capacity of As(Ⅲ) on natural pyrrhotite from 23℃ to 33℃ was 3.5~4.5 mg/g (by As element). The adsorption capacity increased with the increase of temperature, and the adsorption process was a spontaneous endothermic reaction. And the best effect occurred when pH was 7,where the removal rate of As(Ⅲ) was (95.51±0.30)%. PO43- had obvious inhibition on the adsorption. X-ray photoelectron spectroscopy analysis showed that the adsorption involved physical adsorption and chemical adsorption, including site attraction caused by the defect structure of minerals, As and S coordination ion exchange, and the coordination precipitation of iron hydroxide oxide. The results showed that the adsorption of As(Ⅲ) by pyrrhotite simplified the tedious steps of the oxidation of As(Ⅲ) to As(Ⅴ) by materials and methods, and had good prospect of utilization.
As one of the most common pollutants in groundwater, excessive arsenic intake will seriously threaten human health. The kinetics, isotherm and thermodynamics in the adsorption process were analyzed, and the effects of pH and inorganic anions on the adsorption of As(Ⅲ) in water by natural pyrrhotite were studied. It was found that adsorption of As(Ⅲ) by pyrrhotite reached equilibrium in 48 h. Adsorption processes followed the Langmuir isothermal model, in the range of 1~200 mg/L for initial concentration, and the saturated adsorption capacity of As(Ⅲ) on natural pyrrhotite from 23℃ to 33℃ was 3.5~4.5 mg/g (by As element). The adsorption capacity increased with the increase of temperature, and the adsorption process was a spontaneous endothermic reaction. And the best effect occurred when pH was 7,where the removal rate of As(Ⅲ) was (95.51±0.30)%. PO43- had obvious inhibition on the adsorption. X-ray photoelectron spectroscopy analysis showed that the adsorption involved physical adsorption and chemical adsorption, including site attraction caused by the defect structure of minerals, As and S coordination ion exchange, and the coordination precipitation of iron hydroxide oxide. The results showed that the adsorption of As(Ⅲ) by pyrrhotite simplified the tedious steps of the oxidation of As(Ⅲ) to As(Ⅴ) by materials and methods, and had good prospect of utilization.
2021, 39(2): 41-46,88.
doi: 10.13205/j.hjgc.202102007
Abstract:
This paper studied the removal efficiency and mechanism of heavy metals on different types of permeable pavement systems in runoff water. Three typical permeable pavement systems (ceramic permeable bricks, permeable asphalt, and permeable concrete) were set up in the laboratory, and the removal efficiency and mechanism of five common runoff heavy metals (Cu, Zn, Cd, Mn, Ni) were studied. Furthermore, the effects of rainfall recurrence periods (2 a, 3 a, 5 a) were analyzed. The results showed that the three permeable paving systems had good removal efficiencies on all five heavy metals, and compared with permeable asphalt and permeable concrete, ceramic permeable brick showed the best removal and stable removal efficiency. Ceramic permeable bricks and permeable asphalt could reduce the concentration of heavy metals in a shorter time, but the speed of permeable concrete reaching the adsorption point was slower and the effluent concentration was more unstable especially under different rainfall recurrence periods. Different permeable pavement systems exhibited different performance under different rainfall recurrence periods, with an impact degree sequence of 2 a>5 a>3 a. This result showed that permeable pavement systems had excellent and stable removal performance under the rainfall condition of 3 a, while a too large or too small flow rate would reduce the removal efficiency of heavy metal removal.
This paper studied the removal efficiency and mechanism of heavy metals on different types of permeable pavement systems in runoff water. Three typical permeable pavement systems (ceramic permeable bricks, permeable asphalt, and permeable concrete) were set up in the laboratory, and the removal efficiency and mechanism of five common runoff heavy metals (Cu, Zn, Cd, Mn, Ni) were studied. Furthermore, the effects of rainfall recurrence periods (2 a, 3 a, 5 a) were analyzed. The results showed that the three permeable paving systems had good removal efficiencies on all five heavy metals, and compared with permeable asphalt and permeable concrete, ceramic permeable brick showed the best removal and stable removal efficiency. Ceramic permeable bricks and permeable asphalt could reduce the concentration of heavy metals in a shorter time, but the speed of permeable concrete reaching the adsorption point was slower and the effluent concentration was more unstable especially under different rainfall recurrence periods. Different permeable pavement systems exhibited different performance under different rainfall recurrence periods, with an impact degree sequence of 2 a>5 a>3 a. This result showed that permeable pavement systems had excellent and stable removal performance under the rainfall condition of 3 a, while a too large or too small flow rate would reduce the removal efficiency of heavy metal removal.
2021, 39(2): 47-52.
doi: 10.13205/j.hjgc.202102008
Abstract:
By constructing the artificial rainfall system and the collection system of underlying surface runoff, the runoff coefficients of different impervious underlying surface in the city was analyzed. The analysis results of runoff coefficients of underlying surface showed that the average runoff coefficient of urban road was 0.82, which was lower than that of other the non permeable underlying surface (0.87~0.89). This was mainly due to the stronger permeability of urban road made of asphalt material and the strong absorption capacity of its coarse pores to water flow. Rainfall duration and intensity were the key factors affecting runoff coefficient of the underlying surface. The influence of rainfall duration on runoff coefficient of six non permeable underlying surfaces was significant, especially in the initial 20 minutes of rainfall, and the runoff coefficient rise rapidly, which was more than 4 times of the initial value at most; the increase of rainfall intensity was bound to shorten the runoff production time, intensify its impact on runoff coefficient, and make its correlation with runoff coefficient significantly higher than rainfall duration.
By constructing the artificial rainfall system and the collection system of underlying surface runoff, the runoff coefficients of different impervious underlying surface in the city was analyzed. The analysis results of runoff coefficients of underlying surface showed that the average runoff coefficient of urban road was 0.82, which was lower than that of other the non permeable underlying surface (0.87~0.89). This was mainly due to the stronger permeability of urban road made of asphalt material and the strong absorption capacity of its coarse pores to water flow. Rainfall duration and intensity were the key factors affecting runoff coefficient of the underlying surface. The influence of rainfall duration on runoff coefficient of six non permeable underlying surfaces was significant, especially in the initial 20 minutes of rainfall, and the runoff coefficient rise rapidly, which was more than 4 times of the initial value at most; the increase of rainfall intensity was bound to shorten the runoff production time, intensify its impact on runoff coefficient, and make its correlation with runoff coefficient significantly higher than rainfall duration.
2021, 39(2): 53-60,81.
doi: 10.13205/j.hjgc.202102009
Abstract:
Anammox (anaerobic ammonium oxidation) is regarded as the most promising biological denitrification technique, due to its advantages such as no necessity for additional carbon, low sludge yield and low energy consumption. However, anammox bacteria are highly sensitive to external environmental factors, which hinders its large-scale application. Heavy metal ions in industrial sewage are important environmental factors affecting the biological denitrification efficiency of anammox system. Moreover, the effect of heavy metal ions with different types, concentrations and valence state varies significantly. In this paper, the recent research results on the long and short term impact of typical heavy metal ions(Cu2+、Zn2+、Fe2+ and Fe3+) on anammox denitrification system were comprehensively summarized, and the internal mechanism of heavy metal ions acting on anammox microbial community was also systematically analyzed, to provide reference for improving denitrification efficiency.
Anammox (anaerobic ammonium oxidation) is regarded as the most promising biological denitrification technique, due to its advantages such as no necessity for additional carbon, low sludge yield and low energy consumption. However, anammox bacteria are highly sensitive to external environmental factors, which hinders its large-scale application. Heavy metal ions in industrial sewage are important environmental factors affecting the biological denitrification efficiency of anammox system. Moreover, the effect of heavy metal ions with different types, concentrations and valence state varies significantly. In this paper, the recent research results on the long and short term impact of typical heavy metal ions(Cu2+、Zn2+、Fe2+ and Fe3+) on anammox denitrification system were comprehensively summarized, and the internal mechanism of heavy metal ions acting on anammox microbial community was also systematically analyzed, to provide reference for improving denitrification efficiency.
2021, 39(2): 61-65.
doi: 10.13205/j.hjgc.202102010
Abstract:
The experimental sludge, which was taken from a sewage treatment plant, was domesticated into anaerobic activated sludge with phosphate reduction function through cultivation. By adjusting different phosphorus sources (soybean lecithin, bone meal, sodium hexametaphosphate, dipotassium hydrogen phosphate, sodium hypophosphite and sodium phosphite), nitrogen source (ammonium chloride, peptone) and N/P ratio, the gas production efficiency of phosphine and removal rate of phosphate were measured in this research. The results showed that both the phosphorus source and nitrogen source used in this experiment could produce phosphine gas in the phosphate reduction system (PRS), which indicated that the PRS had a good adaptability to various nitrogen and phosphorus compounds. In addition, the inorganic phosphorous sodium as the single phosphorus source, had the largest gas production and the organic phosphorus represented by soybean lecithin produced the least amount of gas. The addition of bone meal and sodium hypophosphite could promote the increase of gas production in PRS. What's more, the inorganic nitrogen ammonium chloride as a nitrogen source, had a large gas production with the optimum ratio of nitrogen to phosphorus of 4:1, while the ratio was also 4:1 when peptone was used as nitrogen source. The mixing of these two nitrogen sources could promote the production of phosphine.
The experimental sludge, which was taken from a sewage treatment plant, was domesticated into anaerobic activated sludge with phosphate reduction function through cultivation. By adjusting different phosphorus sources (soybean lecithin, bone meal, sodium hexametaphosphate, dipotassium hydrogen phosphate, sodium hypophosphite and sodium phosphite), nitrogen source (ammonium chloride, peptone) and N/P ratio, the gas production efficiency of phosphine and removal rate of phosphate were measured in this research. The results showed that both the phosphorus source and nitrogen source used in this experiment could produce phosphine gas in the phosphate reduction system (PRS), which indicated that the PRS had a good adaptability to various nitrogen and phosphorus compounds. In addition, the inorganic phosphorous sodium as the single phosphorus source, had the largest gas production and the organic phosphorus represented by soybean lecithin produced the least amount of gas. The addition of bone meal and sodium hypophosphite could promote the increase of gas production in PRS. What's more, the inorganic nitrogen ammonium chloride as a nitrogen source, had a large gas production with the optimum ratio of nitrogen to phosphorus of 4:1, while the ratio was also 4:1 when peptone was used as nitrogen source. The mixing of these two nitrogen sources could promote the production of phosphine.
2021, 39(2): 66-72.
doi: 10.13205/j.hjgc.202102011
Abstract:
Urine resource utilization is an important direction in the technology related to the rural toilet revolution. Because urine is rich in nitrogen, phosphorus, and potassium, its efficient use becoming a research hot topic. The changes of nutrient elements during urine collection and storage will be affected by a variety of environmental factors and biological activities. Based on the concept of source separated toilet, this research simulated the urine collection process, detected the changes of urine properties during collection and storage process, and measured the key indicators of three batches of fresh urine and one piece of the aged urine sealed for more than 60 days used in this experiment. Different urine had different constituent. In aged urine the ρ(TN) and ρ(TP) were 7.6 g/L and 286 mg/L respectively. The ρ(TN) and ρ(TP) of the fresh urine used in this experiment were lower than the aged urine's and were 5~7 g/L and 371~843 mg/L respectively. Dilution could not inhibit urine hydrolysis, but under high dilution factors, it had a tendency to accelerate urine hydrolysis. Temperature had a great effect on urine hydrolysis. Storage at 35℃ greatly accelerated the hydrolysis of urine. Storage at 4℃ could inhibit the hydrolysis of urine within 30 days; open and seal would not affect the hydrolysis rate of urine, but open storage for 30 days, TN content lost by more than 75% due to volatilization. The 30 days' collection and storage process of the home-type source separation toilet was simulated. It was found that after the 30 days' collection and storage period, the urine hydrolysis rate reached 82%. Combining China's rural toilet revolution with related technologies of source separated urine, we proposed that urine recycling should be combined with the characteristics of urine, regional characteristic of China and the purpose of utilization. The study could provide basic parameters and design references for the urine resource utilization of source-separated toilets.
Urine resource utilization is an important direction in the technology related to the rural toilet revolution. Because urine is rich in nitrogen, phosphorus, and potassium, its efficient use becoming a research hot topic. The changes of nutrient elements during urine collection and storage will be affected by a variety of environmental factors and biological activities. Based on the concept of source separated toilet, this research simulated the urine collection process, detected the changes of urine properties during collection and storage process, and measured the key indicators of three batches of fresh urine and one piece of the aged urine sealed for more than 60 days used in this experiment. Different urine had different constituent. In aged urine the ρ(TN) and ρ(TP) were 7.6 g/L and 286 mg/L respectively. The ρ(TN) and ρ(TP) of the fresh urine used in this experiment were lower than the aged urine's and were 5~7 g/L and 371~843 mg/L respectively. Dilution could not inhibit urine hydrolysis, but under high dilution factors, it had a tendency to accelerate urine hydrolysis. Temperature had a great effect on urine hydrolysis. Storage at 35℃ greatly accelerated the hydrolysis of urine. Storage at 4℃ could inhibit the hydrolysis of urine within 30 days; open and seal would not affect the hydrolysis rate of urine, but open storage for 30 days, TN content lost by more than 75% due to volatilization. The 30 days' collection and storage process of the home-type source separation toilet was simulated. It was found that after the 30 days' collection and storage period, the urine hydrolysis rate reached 82%. Combining China's rural toilet revolution with related technologies of source separated urine, we proposed that urine recycling should be combined with the characteristics of urine, regional characteristic of China and the purpose of utilization. The study could provide basic parameters and design references for the urine resource utilization of source-separated toilets.
2021, 39(2): 73-81.
doi: 10.13205/j.hjgc.202102012
Abstract:
To quickly and accurately locate contaminant sources in dynamic indoor environments, this study presented a multi-robot source localization method (URPSO) by integrating concentration and airflow information and validated the method by combining robot experiments with numerical simulations. The experimental study was first conducted by using three mobile robots to locate an ethanol source in a typical dynamic indoor environment with a fan swinging periodically from left to right. A total of 14 out of 15 experiments were successful, with a success rate of 93.3%, indicating that the method had strong robustness. Next, according to the experimental environment, numerical robot experiments for locating the ethanol source were conducted. The results showed that the success rate and the average number of steps from numerical experiments were consistent with those from robot experiments, indicating the feasibility of using numerical simulations. Finally, 100 numerical experiments were further conducted by using URPSO method to locate an ethanol source in three typical dynamic indoor environments (mixing ventilation case MV, displacement ventilation case DV and natural ventilation case NV), respectively. For MV, DV and NV, the success rates were 100%, 92% and 81% respectively, indicating that URPSO method had high success rates in different dynamic indoor environments.
To quickly and accurately locate contaminant sources in dynamic indoor environments, this study presented a multi-robot source localization method (URPSO) by integrating concentration and airflow information and validated the method by combining robot experiments with numerical simulations. The experimental study was first conducted by using three mobile robots to locate an ethanol source in a typical dynamic indoor environment with a fan swinging periodically from left to right. A total of 14 out of 15 experiments were successful, with a success rate of 93.3%, indicating that the method had strong robustness. Next, according to the experimental environment, numerical robot experiments for locating the ethanol source were conducted. The results showed that the success rate and the average number of steps from numerical experiments were consistent with those from robot experiments, indicating the feasibility of using numerical simulations. Finally, 100 numerical experiments were further conducted by using URPSO method to locate an ethanol source in three typical dynamic indoor environments (mixing ventilation case MV, displacement ventilation case DV and natural ventilation case NV), respectively. For MV, DV and NV, the success rates were 100%, 92% and 81% respectively, indicating that URPSO method had high success rates in different dynamic indoor environments.
2021, 39(2): 82-88.
doi: 10.13205/j.hjgc.202102013
Abstract:
The release law of malodorous gases (volatile sulfide (VSC) and ammonia) during municipal sludge composting was investiagted in this paper, by taking a municipal sludge composting plant in North China as the research object. The spatial distribution of VSC and ammonia in the sludge composting plant and the release law in the composting process were determined by Suma tank and static box collection and then gas chromatography. The results indicated that the main components in the composting process of sludge were ammonia, dimethyl sulfide and dimethyl disulfide, and the order of cumulative concentration in the static tank for 20 minutes was NH3>DMDS>DMS>CS2>MT>H2S. The average cumulative concentration of NH3 was 2.62~119.64 mg/m3, and the cumulative concentration of VSC was 1~2 orders of magnitude lower than that of NH3. Through this study, the types and contents of main gaseous pollutants in municipal sludge composting process were determined, which provided effective data support for engineering of odor treatment.
The release law of malodorous gases (volatile sulfide (VSC) and ammonia) during municipal sludge composting was investiagted in this paper, by taking a municipal sludge composting plant in North China as the research object. The spatial distribution of VSC and ammonia in the sludge composting plant and the release law in the composting process were determined by Suma tank and static box collection and then gas chromatography. The results indicated that the main components in the composting process of sludge were ammonia, dimethyl sulfide and dimethyl disulfide, and the order of cumulative concentration in the static tank for 20 minutes was NH3>DMDS>DMS>CS2>MT>H2S. The average cumulative concentration of NH3 was 2.62~119.64 mg/m3, and the cumulative concentration of VSC was 1~2 orders of magnitude lower than that of NH3. Through this study, the types and contents of main gaseous pollutants in municipal sludge composting process were determined, which provided effective data support for engineering of odor treatment.
2021, 39(2): 89-97,104.
doi: 10.13205/j.hjgc.202102014
Abstract:
In recent years, the quality of the atmospheric environment in many cities has become increasingly severe, which is not only related to the emission of pollutants from local sources, but also affected by regional transportation. Taking an air pollution process as an example in Shenyang, Liaoning in January 2017, the evolution process and meteorological impact were analyzed. Firstly, the WRF-HYSPLIT model was used to calculate the backward trajectories, and the WRF-Chem air quality model was used to calculate the ground surface PM2.5 particle diffusion process. At the same time, the surface synoptic map and isobaric surface in the study area was analyzed and simulated. The results showed that the air mass trajectory pathways in January 2017 could be divided into 5 types, in which the trajectory cluster 1 in the west direction had the fastest moving speed, but the pollution value and frequency were lower. And the transport pathways numbered 2 and 3 were similar originating in the Inner Mongolia Autonomous Region and moving to the southeast direction to the target area. And these trajectories carried low PM2.5 value of 45.47, 67.97 μg/m3, with frequency of 24.19% and 15.32%, respectively. The cluster 4 showed that the local source transports accounted for 33.03% with the largest pollution level, which was 121.66 μg/m3. The trajectory cluster 5 in the southwest transport pathway had a frequency of 14.53% and the PM2.5 value of 105.5 μg/m3. The results of air quality model were consistent with the trajectories calculation results:the southwest and the northeast transport pathways led to a particulate matter increase in the target area. Heavy pollution events were more likely to occur due to the impact of Northeast China Topographic Trough and Changbai Mountain Small High Pressure formed by topographical dynamics and thermal factors.
In recent years, the quality of the atmospheric environment in many cities has become increasingly severe, which is not only related to the emission of pollutants from local sources, but also affected by regional transportation. Taking an air pollution process as an example in Shenyang, Liaoning in January 2017, the evolution process and meteorological impact were analyzed. Firstly, the WRF-HYSPLIT model was used to calculate the backward trajectories, and the WRF-Chem air quality model was used to calculate the ground surface PM2.5 particle diffusion process. At the same time, the surface synoptic map and isobaric surface in the study area was analyzed and simulated. The results showed that the air mass trajectory pathways in January 2017 could be divided into 5 types, in which the trajectory cluster 1 in the west direction had the fastest moving speed, but the pollution value and frequency were lower. And the transport pathways numbered 2 and 3 were similar originating in the Inner Mongolia Autonomous Region and moving to the southeast direction to the target area. And these trajectories carried low PM2.5 value of 45.47, 67.97 μg/m3, with frequency of 24.19% and 15.32%, respectively. The cluster 4 showed that the local source transports accounted for 33.03% with the largest pollution level, which was 121.66 μg/m3. The trajectory cluster 5 in the southwest transport pathway had a frequency of 14.53% and the PM2.5 value of 105.5 μg/m3. The results of air quality model were consistent with the trajectories calculation results:the southwest and the northeast transport pathways led to a particulate matter increase in the target area. Heavy pollution events were more likely to occur due to the impact of Northeast China Topographic Trough and Changbai Mountain Small High Pressure formed by topographical dynamics and thermal factors.
2021, 39(2): 98-104.
doi: 10.13205/j.hjgc.202102015
Abstract:
There were 106 dustfall samples collected from Wuhan universities during November 2017. Nine types of water-soluble ions (F-, Cl-, NO3-, SO42-, Na+, NH4+, K+, Mg2+, Ca2+) were analyzed by ion chromatography. Correlation analysis and ratio analysis were used to analyze the pollution characteristics, and the PCA-MLR model was used to discuss its source and contribution rate. The results showed that the main water-soluble ions in dust reduction in Wuhan universities were Ca2+, SO42- and NO3-, and the average concentration order was Ca2+>SO42->NO3->K+>Na+>Cl->Mg2+>NH4+>F-. There were obvious spatial qualitative differences in the distribution of F-, Cl-, NO3-, SO42-, Na+, K+, Mg2+ and Ca2+. The mass ratio of NO3-/SO42- was 0.28, which was dominated by fixed-source pollution; the dust-reducing samples were generally alkaline. Nine types of soluble ions existed mainly in forms of NaCl, KCl, MgCl2, Mg (NO3)2, MgSO4, Ca(NO3)2, CaSO4, etc., mainly from soil/transport mixed sources, combustion sources, industrial source, and their contribution rates were 8%, 12% and 80%, respectively.
There were 106 dustfall samples collected from Wuhan universities during November 2017. Nine types of water-soluble ions (F-, Cl-, NO3-, SO42-, Na+, NH4+, K+, Mg2+, Ca2+) were analyzed by ion chromatography. Correlation analysis and ratio analysis were used to analyze the pollution characteristics, and the PCA-MLR model was used to discuss its source and contribution rate. The results showed that the main water-soluble ions in dust reduction in Wuhan universities were Ca2+, SO42- and NO3-, and the average concentration order was Ca2+>SO42->NO3->K+>Na+>Cl->Mg2+>NH4+>F-. There were obvious spatial qualitative differences in the distribution of F-, Cl-, NO3-, SO42-, Na+, K+, Mg2+ and Ca2+. The mass ratio of NO3-/SO42- was 0.28, which was dominated by fixed-source pollution; the dust-reducing samples were generally alkaline. Nine types of soluble ions existed mainly in forms of NaCl, KCl, MgCl2, Mg (NO3)2, MgSO4, Ca(NO3)2, CaSO4, etc., mainly from soil/transport mixed sources, combustion sources, industrial source, and their contribution rates were 8%, 12% and 80%, respectively.
2021, 39(2): 105-109,159.
doi: 10.13205/j.hjgc.202102016
Abstract:
With the rapid promotion of waste classification in China, kitchen waste utilization will have a great influence on the energy recovery efficiency of municipal solid waste. Therefore, urban waste treatment infrastructure should be reconsidered. The objective of this work was to measure the moisture contents and heating values of municipal solid waste from 20 communities in Zhangjiagang through field investigation, and predict the changes of moisture contents and heating values of dry waste under different separation rates of kitchen waste. The results showed that based on the existing domestic waste treatment facilities in Zhangjiagang, the separation rate of kitchen waste was not the higher the better. Under the optimized separation rate of 70.8%, zero primary landfill could be realized, and energy recovery efficiency from municipal solid waste could reach the maximum. For the new era of waste classification, the results obtained in this paper was of guiding significance in design of municipal solid waste management scheme for urban administration.
With the rapid promotion of waste classification in China, kitchen waste utilization will have a great influence on the energy recovery efficiency of municipal solid waste. Therefore, urban waste treatment infrastructure should be reconsidered. The objective of this work was to measure the moisture contents and heating values of municipal solid waste from 20 communities in Zhangjiagang through field investigation, and predict the changes of moisture contents and heating values of dry waste under different separation rates of kitchen waste. The results showed that based on the existing domestic waste treatment facilities in Zhangjiagang, the separation rate of kitchen waste was not the higher the better. Under the optimized separation rate of 70.8%, zero primary landfill could be realized, and energy recovery efficiency from municipal solid waste could reach the maximum. For the new era of waste classification, the results obtained in this paper was of guiding significance in design of municipal solid waste management scheme for urban administration.
2021, 39(2): 110-115.
doi: 10.13205/j.hjgc.202102017
Abstract:
In recent years, the total domestic garbage in China has been increasing at a rate of 10% per year. However, the technology for the classification and treatment of domestic garbage is relatively limited and backward. The classification method based on machine vision has been widely used. Traditional visual classification net currently faces the problems of sophisticated parameters, large amount of calculation, low classification accuracy, and long classification time. Therefore, this paper proposed to use Max-AVE Pooling instead of Max Pooling or AVE Pooling in ResNet-50Bottleneck, and use the depth separable convolution instead of the standard convolution method in ResNet-50Bottleneck to classify junk images. The experimental results showed that the lightweight residual network (MaxAVE-Pooling-MobileNet-18, MAPMobileNet-18) proposed in this paper could significantly reduce the parameter amount by 10 times and the calculation amount by 14 times, and slightly improve the accuracy compared with the classical classification network. It is very suitable for the implementation and application of mobile phones and embedded devices.
In recent years, the total domestic garbage in China has been increasing at a rate of 10% per year. However, the technology for the classification and treatment of domestic garbage is relatively limited and backward. The classification method based on machine vision has been widely used. Traditional visual classification net currently faces the problems of sophisticated parameters, large amount of calculation, low classification accuracy, and long classification time. Therefore, this paper proposed to use Max-AVE Pooling instead of Max Pooling or AVE Pooling in ResNet-50Bottleneck, and use the depth separable convolution instead of the standard convolution method in ResNet-50Bottleneck to classify junk images. The experimental results showed that the lightweight residual network (MaxAVE-Pooling-MobileNet-18, MAPMobileNet-18) proposed in this paper could significantly reduce the parameter amount by 10 times and the calculation amount by 14 times, and slightly improve the accuracy compared with the classical classification network. It is very suitable for the implementation and application of mobile phones and embedded devices.
2021, 39(2): 116-120,124.
doi: 10.13205/j.hjgc.202102018
Abstract:
In order to explore the resource utilization of stale refuse in formal landfill, in this study, a municipal solid waste landfill in Beijing was taken as the research object. According to the size, mixed samples were divided into several groups and sorted manually, and their physical and chemical properties were analyzed. The results showed that stale refuse from the group of 0~60 mm were mainly humus soil and accounting for 53.08% of total stale refuse, and grain size of the combustible refuse such as plastic were mainly concentrated in 60 mm above, accounting for 30.46% of total stale refuse. Therefore, the stale waste of the landfill could be screened by 60 mm mesh to realize the coarse classification of humus soil and combustible refuse. Referring to the control standards for urban wastes for agricultural use (GB 8172-1987), the overall total nitrogen content was low in humus soil, and ascaris egg mortality exceeded the standard at some individual points, and other items in humus soil were qualified, which could realize reuse through composting, nitrogen sources supplement and cement kiln alternative raw materials. After screening, the average calorific value of combustible refuse reached 23.13 MJ/kg, and the moisture content and ash content were 15.32% and 10.21% respectively. According to the code for design of industrial waste co-composition in cement kiln (GB 50634-2010). Combustible refuse can be reused as a cement kiln alternative fuels.
In order to explore the resource utilization of stale refuse in formal landfill, in this study, a municipal solid waste landfill in Beijing was taken as the research object. According to the size, mixed samples were divided into several groups and sorted manually, and their physical and chemical properties were analyzed. The results showed that stale refuse from the group of 0~60 mm were mainly humus soil and accounting for 53.08% of total stale refuse, and grain size of the combustible refuse such as plastic were mainly concentrated in 60 mm above, accounting for 30.46% of total stale refuse. Therefore, the stale waste of the landfill could be screened by 60 mm mesh to realize the coarse classification of humus soil and combustible refuse. Referring to the control standards for urban wastes for agricultural use (GB 8172-1987), the overall total nitrogen content was low in humus soil, and ascaris egg mortality exceeded the standard at some individual points, and other items in humus soil were qualified, which could realize reuse through composting, nitrogen sources supplement and cement kiln alternative raw materials. After screening, the average calorific value of combustible refuse reached 23.13 MJ/kg, and the moisture content and ash content were 15.32% and 10.21% respectively. According to the code for design of industrial waste co-composition in cement kiln (GB 50634-2010). Combustible refuse can be reused as a cement kiln alternative fuels.
2021, 39(2): 121-124.
doi: 10.13205/j.hjgc.202102019
Abstract:
The outstanding characteristics of sewage sludge are the high moisture content. The moisture of sewage sludge cake after mechanical dewatering is still as high as 80%. It is difficult to sewage sludge treatment both efficiently and economically, due to its high moisture content and bulkiness. However, decreasing the moisture content of sludge is the crux of the matter in harmlessness and bulkiness reduction, which is also the premise of resource utilization. Heating drying is one of the most effective methods of sludge deep dehydration, but the traditional hot air convection drying has many problems, such as low efficiency, high energy consumption and difficult tail gas treatment. Heat pump drying is a new technology of sludge low temperature drying, which has the advantages of low energy consumption, easy control of drying process and high safety performance. However, it is necessary to consider the size and stability of the sludge particles entering the dryer, coordinate the heat and mass transfer inside and outside the sludge particles, and deal with the impact of the dust and corrosive gas in the drying process on the heat pump heat exchanger.
The outstanding characteristics of sewage sludge are the high moisture content. The moisture of sewage sludge cake after mechanical dewatering is still as high as 80%. It is difficult to sewage sludge treatment both efficiently and economically, due to its high moisture content and bulkiness. However, decreasing the moisture content of sludge is the crux of the matter in harmlessness and bulkiness reduction, which is also the premise of resource utilization. Heating drying is one of the most effective methods of sludge deep dehydration, but the traditional hot air convection drying has many problems, such as low efficiency, high energy consumption and difficult tail gas treatment. Heat pump drying is a new technology of sludge low temperature drying, which has the advantages of low energy consumption, easy control of drying process and high safety performance. However, it is necessary to consider the size and stability of the sludge particles entering the dryer, coordinate the heat and mass transfer inside and outside the sludge particles, and deal with the impact of the dust and corrosive gas in the drying process on the heat pump heat exchanger.
2021, 39(2): 125-130.
doi: 10.13205/j.hjgc.202102020
Abstract:
To improve the efficiency of methane production by anaerobic digestion process of municipal sludge, rusted scrap iron produced by mechanical processing plant was added to the sludge mixing with some kitchen waste to increase organic matters composition, and same amount of pure iron powder was added as the control group. The methane production effect of rusted scrap iron and pure iron powder was compared, after anaerobic digestion at medium temperature (39±1)℃ for 30 days. The results showed that the cumulative methane production in the rusted scrap iron group and the iron powder group reached 340.33 mL/g and 336.52 mL/g, respectively, which increased by 54% and 52% compared with the blank group; the volatile organic acids produced by the above two groups on the tenth day of anaerobic digestion were 11051 mg/L and 10800 mg/L, respectively, which were 16% and 12% higher than that of the blank group; as to the proportion of daily gas production components, on the first day, the proportion of H2 for rusted scrap iron group and pure iron powder group were increased by 24% and 12%, compared with that of the blank group; on the 25th day, the proportion of CH4 for rusted scrap iron group and pure iron powder group were 35% and 30% higher than that of blank group. The porous FeOOH in the rusted scrap iron led to a loose structure for microbial flocs, which resulted in a significant methanogenic effect of anaerobic digestion process than that of pure iron powder.
To improve the efficiency of methane production by anaerobic digestion process of municipal sludge, rusted scrap iron produced by mechanical processing plant was added to the sludge mixing with some kitchen waste to increase organic matters composition, and same amount of pure iron powder was added as the control group. The methane production effect of rusted scrap iron and pure iron powder was compared, after anaerobic digestion at medium temperature (39±1)℃ for 30 days. The results showed that the cumulative methane production in the rusted scrap iron group and the iron powder group reached 340.33 mL/g and 336.52 mL/g, respectively, which increased by 54% and 52% compared with the blank group; the volatile organic acids produced by the above two groups on the tenth day of anaerobic digestion were 11051 mg/L and 10800 mg/L, respectively, which were 16% and 12% higher than that of the blank group; as to the proportion of daily gas production components, on the first day, the proportion of H2 for rusted scrap iron group and pure iron powder group were increased by 24% and 12%, compared with that of the blank group; on the 25th day, the proportion of CH4 for rusted scrap iron group and pure iron powder group were 35% and 30% higher than that of blank group. The porous FeOOH in the rusted scrap iron led to a loose structure for microbial flocs, which resulted in a significant methanogenic effect of anaerobic digestion process than that of pure iron powder.
2021, 39(2): 131-135.
doi: 10.13205/j.hjgc.202102021
Abstract:
In this study, municipal sludge conditioning experiments and mechanical filter press dewatering of the conditioned sludge were performed to investigate the influence of the addition of semi-coke during the conditioning step, and the filtration pressure on the water content of the resulting sludge filter cake. The results indicated that the water content of sludge cake decreased with increasing amount of semi-coke added and filtration pressure. When the addition amount of semi-coke was 4 g/100 mL sludge (water content of 95%) with a filtration pressure of 1.6 MPa, the water content was reduced from 80% to 32.19%. The semi-industrial operation of sludge conditioning and dewatering based on semi-coke validated the conclusions above. In addition, it was found that the heat value of the sludge filter cake was improved from 7.82 MJ/kg to 15.29 MJ/kg through the addition of semi-coke, enabling the direct power generation and replacing the combustion of coal. The combination of semi-coke-aided conditioning and mechanical filter press dewatering of municipal sludge could achieve the efficient utilization of sludge as an energy source, which was significant to resource conservation and environmental protection.
In this study, municipal sludge conditioning experiments and mechanical filter press dewatering of the conditioned sludge were performed to investigate the influence of the addition of semi-coke during the conditioning step, and the filtration pressure on the water content of the resulting sludge filter cake. The results indicated that the water content of sludge cake decreased with increasing amount of semi-coke added and filtration pressure. When the addition amount of semi-coke was 4 g/100 mL sludge (water content of 95%) with a filtration pressure of 1.6 MPa, the water content was reduced from 80% to 32.19%. The semi-industrial operation of sludge conditioning and dewatering based on semi-coke validated the conclusions above. In addition, it was found that the heat value of the sludge filter cake was improved from 7.82 MJ/kg to 15.29 MJ/kg through the addition of semi-coke, enabling the direct power generation and replacing the combustion of coal. The combination of semi-coke-aided conditioning and mechanical filter press dewatering of municipal sludge could achieve the efficient utilization of sludge as an energy source, which was significant to resource conservation and environmental protection.
2021, 39(2): 136-140,15.
doi: 10.13205/j.hjgc.202102022
Abstract:
To develop an assessment system for evaluating the construction level of municipal solid waste comprehensive treatment parks (MSWCTPs) in zero-waste cities, specific indicators were determined by Delphi method, and the weight of each indicator was calculated by analytic hierarchy process (AHP) and the evaluation index was quantified by five-point score system. This assessment system integrated three modules, i.e., the target, the criterion and the index. From the perspective of site selection, function, process, pollution control, management, etc., 25 evaluation criterias were identified and summarized into six groups, including site selection and layout of the park, treatment and disposal capacity, process route, pollution control technology, environmental management mechanism and measures for neighbor benefit harmony. The evaluation index was quantified and the weight of each index was assigned to assess the construction level of MSWCTPs. This system was then applied to four MSWCTPs in South China. The construction level scores of the four MSWCTPs were 3.36 (good), 2.12 (fair), 2.10 (fair), and 1.82 (poor), respectively.
To develop an assessment system for evaluating the construction level of municipal solid waste comprehensive treatment parks (MSWCTPs) in zero-waste cities, specific indicators were determined by Delphi method, and the weight of each indicator was calculated by analytic hierarchy process (AHP) and the evaluation index was quantified by five-point score system. This assessment system integrated three modules, i.e., the target, the criterion and the index. From the perspective of site selection, function, process, pollution control, management, etc., 25 evaluation criterias were identified and summarized into six groups, including site selection and layout of the park, treatment and disposal capacity, process route, pollution control technology, environmental management mechanism and measures for neighbor benefit harmony. The evaluation index was quantified and the weight of each index was assigned to assess the construction level of MSWCTPs. This system was then applied to four MSWCTPs in South China. The construction level scores of the four MSWCTPs were 3.36 (good), 2.12 (fair), 2.10 (fair), and 1.82 (poor), respectively.
2021, 39(2): 141-146,152.
doi: 10.13205/j.hjgc.202102023
Abstract:
Taking the sediment disposal demonstration project of Yihe River in Shandong province as an example, the ecological risks of sediment after three years of geo-textile tube landfill and reduction disposal were tracked to explore the effects of different disposal methods on the safety of heavy metals in sediments. The total concentrations and geochemical fractions of Cr, As, Zn, Cu, Cd, Pb, and Hg in sediments by the two disposal methods were analyzed. Meanwhile, their ecological risks and environmental safety were assessed by leaching toxicity method, risk assessment code (RAC), and potential ecological risk index method (PERI). The obtained results showed total concentrations of As, Cd, and Hg in sediments from two different disposal sites exceeded the risk screening value of the Soil Environmental Quality Risk Control Standard for Soil Contamination of Agricultural Land (GB 15618-2018). The geochemical fraction distribution of Zn and Hg in the sediments of the two sites was quite different, and the difference was mainly related to the differences of two disposal methods. The leaching toxicity test showed that the leaching toxicity of Cr, As, and Cu in geo-textile tube landfill was higher than that in reduction disposal, while the leaching toxity of Zn was on the contrary. According to the results of leaching toxicity, RAC, and PERI, the ecological risk of geo-textile tube landfill was relatively higher. In order to maximize the environmental and economic benefits, it was necessary to weigh all aspects of factors when choosing which way to treat the dredged sediments.
Taking the sediment disposal demonstration project of Yihe River in Shandong province as an example, the ecological risks of sediment after three years of geo-textile tube landfill and reduction disposal were tracked to explore the effects of different disposal methods on the safety of heavy metals in sediments. The total concentrations and geochemical fractions of Cr, As, Zn, Cu, Cd, Pb, and Hg in sediments by the two disposal methods were analyzed. Meanwhile, their ecological risks and environmental safety were assessed by leaching toxicity method, risk assessment code (RAC), and potential ecological risk index method (PERI). The obtained results showed total concentrations of As, Cd, and Hg in sediments from two different disposal sites exceeded the risk screening value of the Soil Environmental Quality Risk Control Standard for Soil Contamination of Agricultural Land (GB 15618-2018). The geochemical fraction distribution of Zn and Hg in the sediments of the two sites was quite different, and the difference was mainly related to the differences of two disposal methods. The leaching toxicity test showed that the leaching toxicity of Cr, As, and Cu in geo-textile tube landfill was higher than that in reduction disposal, while the leaching toxity of Zn was on the contrary. According to the results of leaching toxicity, RAC, and PERI, the ecological risk of geo-textile tube landfill was relatively higher. In order to maximize the environmental and economic benefits, it was necessary to weigh all aspects of factors when choosing which way to treat the dredged sediments.
2021, 39(2): 147-152.
doi: 10.13205/j.hjgc.202102024
Abstract:
In order to scientifically and reasonably assess the soil health risks of agricultural land, based on the environmental risk assessment system of the US Environmental Protection Agency, this paper established a soil health risk assessment model for agricultural land use in China. Monte Carlo simulations were also introduced to reduce the uncertainty of risk assessment results. The health risk assessment results of heavy metals in regional agricultural land soils showed that the total carcinogenic risk CR caused by the agricultural land obeyed a log-normal distribution, which was (2.898±2.425)×10-4, and the total hazard index HQ obeyed a log-normal distribution, which was 15.775±13.797, the priority soil control pollutant was determined to be As, and the priority control exposure route was oral route. The model was applicable to the evaluation of human health risks by multiple pollutants in agricultural land, and could obtain key information such as priority control factors and priority control for exposure routes.
In order to scientifically and reasonably assess the soil health risks of agricultural land, based on the environmental risk assessment system of the US Environmental Protection Agency, this paper established a soil health risk assessment model for agricultural land use in China. Monte Carlo simulations were also introduced to reduce the uncertainty of risk assessment results. The health risk assessment results of heavy metals in regional agricultural land soils showed that the total carcinogenic risk CR caused by the agricultural land obeyed a log-normal distribution, which was (2.898±2.425)×10-4, and the total hazard index HQ obeyed a log-normal distribution, which was 15.775±13.797, the priority soil control pollutant was determined to be As, and the priority control exposure route was oral route. The model was applicable to the evaluation of human health risks by multiple pollutants in agricultural land, and could obtain key information such as priority control factors and priority control for exposure routes.
2021, 39(2): 153-159.
doi: 10.13205/j.hjgc.202102025
Abstract:
The environmental management framework of contaminated sites is not completed in China, and there is often lack of clear understanding about environmental impacts in the process of remediation technology development or program selection. As a result, sometimes secondary pollution caused by remediation is ignored. The research established the environmental indexes including pollutant discharge, environmental sensitivity, environmental risk, soil and ecological environment, laws, regulations and standards, and social acceptability based on green and sustainable principle. The environmental comparison between two remediation technologies was carried out at an abandoned coking site in Beijing. The result showed that the emission of CO2 and organized atmospheric pollutants of thermal desorption in situ were 6.0, 1.49 times larger than that of ex-situ thermal desorption, since the latter had advantages in energy saving and emission reduction. While the indexes such as environmental risk, sensitivity and social acceptance of in-situ thermal desorption were better and the in-situ program was chosen as the preferred plan. How to reduce emission of pollutants and lower environmental risks further was the key point to improve the two programs respectively. The index system could be used for screening or optimizing the remediation schemes by identifying critical environmental factors.
The environmental management framework of contaminated sites is not completed in China, and there is often lack of clear understanding about environmental impacts in the process of remediation technology development or program selection. As a result, sometimes secondary pollution caused by remediation is ignored. The research established the environmental indexes including pollutant discharge, environmental sensitivity, environmental risk, soil and ecological environment, laws, regulations and standards, and social acceptability based on green and sustainable principle. The environmental comparison between two remediation technologies was carried out at an abandoned coking site in Beijing. The result showed that the emission of CO2 and organized atmospheric pollutants of thermal desorption in situ were 6.0, 1.49 times larger than that of ex-situ thermal desorption, since the latter had advantages in energy saving and emission reduction. While the indexes such as environmental risk, sensitivity and social acceptance of in-situ thermal desorption were better and the in-situ program was chosen as the preferred plan. How to reduce emission of pollutants and lower environmental risks further was the key point to improve the two programs respectively. The index system could be used for screening or optimizing the remediation schemes by identifying critical environmental factors.
2021, 39(2): 160-165,172.
doi: 10.13205/j.hjgc.202102026
Abstract:
This study investigated the feasibility of atrazine degradation in soil by using Fe2+-activated hypochlorite (NaClO). The effect of main factors such as oxidant dosage, the Fe2+ to NaClO molar ratio, initial soil pH, etc. on the degradation of atrazine was considered. The results showed that after 8 h reaction, 82% of atrazine could be degraded when NaClO dosage was 10 mmol at Fe2+/NaClO molar ratio of 1:1. The degradation of atrazine followed the pseudo-first-order model. ESR result confirmed that the Fe2+/NaClO system yielded more HO· than that of NaOCl alone to participate in atrazine degradation. The Fe2+/NaClO process could operate over a wide pH range (3~9), while humic acid and inorganic anions (Cl-, HCO3-) in the soil matrix had a negative effect on atrazine degradation. After the Fe2+/NaClO treatment, the soil microbial community was obviously affected, and the relative abundance of Proteobacteria rose from 25.46% to 72.73%.
This study investigated the feasibility of atrazine degradation in soil by using Fe2+-activated hypochlorite (NaClO). The effect of main factors such as oxidant dosage, the Fe2+ to NaClO molar ratio, initial soil pH, etc. on the degradation of atrazine was considered. The results showed that after 8 h reaction, 82% of atrazine could be degraded when NaClO dosage was 10 mmol at Fe2+/NaClO molar ratio of 1:1. The degradation of atrazine followed the pseudo-first-order model. ESR result confirmed that the Fe2+/NaClO system yielded more HO· than that of NaOCl alone to participate in atrazine degradation. The Fe2+/NaClO process could operate over a wide pH range (3~9), while humic acid and inorganic anions (Cl-, HCO3-) in the soil matrix had a negative effect on atrazine degradation. After the Fe2+/NaClO treatment, the soil microbial community was obviously affected, and the relative abundance of Proteobacteria rose from 25.46% to 72.73%.
2021, 39(2): 166-172.
doi: 10.13205/j.hjgc.202102027
Abstract:
In this study, the contents and vertical distribution and migration characteristics of eight common toxic heavy metals(Cd, Cr, Cu, Zn, Pb, As, Hg, Ni) in the soil profile of farmland were analyzed and evaluated by Hakanson potential ecological risk index method. The results showed that Cd, Cr, Cu, Zn, Pb, As, Hg, and Ni were detected in the soil, however, only the average value of the Cd content in the surface soil exceeded the screening risk of soil pollution, indicating that Cd pollution in the top layer of the farmland soil was serious. By analyzing the vertical distribution and migration characteristics of heavy metals in the soil profile of farmland, it was found that Cu, Zn, As, Cd, Hg, and Pb were mainly concentrated in the surface layer except for Cr and Ni. The potential ecological risk assessment results suggested that Cd possessed strongly ecological risk in the top and middle soil, while medium ecological risk in the bottom layer; Cr, Ni, Cu, Zn, As, Hg, and Pb were slightly ecological risk in the top, middle, and bottom soils, indicating that Cd was the main ecological risk factor in different soil layers in the area. The results also showed that the surface soil was of medium ecological risk, and the middle and bottom soils was of slightly ecological risk. In conclusion, the ecological risk of heavy metals in the surface soil of farmland was relatively high, mainly caused by Cd pollution. Therefore, it was necessary to adopt safe use measures such as agronomic regulation or alternative cultivation for risk management to ensure the quality and safety of agricultural products.
In this study, the contents and vertical distribution and migration characteristics of eight common toxic heavy metals(Cd, Cr, Cu, Zn, Pb, As, Hg, Ni) in the soil profile of farmland were analyzed and evaluated by Hakanson potential ecological risk index method. The results showed that Cd, Cr, Cu, Zn, Pb, As, Hg, and Ni were detected in the soil, however, only the average value of the Cd content in the surface soil exceeded the screening risk of soil pollution, indicating that Cd pollution in the top layer of the farmland soil was serious. By analyzing the vertical distribution and migration characteristics of heavy metals in the soil profile of farmland, it was found that Cu, Zn, As, Cd, Hg, and Pb were mainly concentrated in the surface layer except for Cr and Ni. The potential ecological risk assessment results suggested that Cd possessed strongly ecological risk in the top and middle soil, while medium ecological risk in the bottom layer; Cr, Ni, Cu, Zn, As, Hg, and Pb were slightly ecological risk in the top, middle, and bottom soils, indicating that Cd was the main ecological risk factor in different soil layers in the area. The results also showed that the surface soil was of medium ecological risk, and the middle and bottom soils was of slightly ecological risk. In conclusion, the ecological risk of heavy metals in the surface soil of farmland was relatively high, mainly caused by Cd pollution. Therefore, it was necessary to adopt safe use measures such as agronomic regulation or alternative cultivation for risk management to ensure the quality and safety of agricultural products.
