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2022 Vol. 40, No. 2
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2022, 40(2): 1-7,26.
doi: 10.13205/j.hjgc.202202001
Abstract:
In this paper, the current situation of water resources, the history and current situation of sewage treatment and reclaimed water utilization in Australia were sorted out and analyzed in detail, and the development history, relevant standards, policies, laws and regulations, and typical cases of reclaimed water utilization in Australia were summarized. The above experience can provide important guidance and technical support for the research and engineering practice of reclaimed water recycling in China. Draw lessons from Australia water reuse technology and management methods, the further development of our country wastewater advanced treatment technology and renewable technology, improve the quality of the reclaimed water production, expand the approaches of reclaimed water use and through concentration control combined with process requirements promote renewable water quality security ability, establish and improve the sewage recycle technology and the management standard system.
In this paper, the current situation of water resources, the history and current situation of sewage treatment and reclaimed water utilization in Australia were sorted out and analyzed in detail, and the development history, relevant standards, policies, laws and regulations, and typical cases of reclaimed water utilization in Australia were summarized. The above experience can provide important guidance and technical support for the research and engineering practice of reclaimed water recycling in China. Draw lessons from Australia water reuse technology and management methods, the further development of our country wastewater advanced treatment technology and renewable technology, improve the quality of the reclaimed water production, expand the approaches of reclaimed water use and through concentration control combined with process requirements promote renewable water quality security ability, establish and improve the sewage recycle technology and the management standard system.
2022, 40(2): 8-13,126.
doi: 10.13205/j.hjgc.202202002
Abstract:
The cobalt-iron layered double hydroxide structure carrier(CoFe-LDH) was successfully prepared by the co-precipitation method, and the active component Mn was loaded by the impregnation method and calcined to prepare the hydrotalcite-like structure catalyst MnxCoFe-LDO catalyst with different Mn loadings(Where x was the mass ratio of manganese nitrate solution to CoFe-LDH). The catalytic performance of the catalyst on nitrogen oxides(NOx) and chlorinated volatile organic compounds(CVOCs) in typical industrial exhaust gas was explored, and the catalyst was characterized by XRD, H2-TPR, NH3-TPD and TEM-EDX mapping. The results showed that the addition of Mn greatly improved the catalytic performance of CoFe-LDO. Among them, the catalyst with a mass ratio of 0.25 had the highest activity. The denitration efficiency was maintained above 90% in the test temperature range, and the efficiency of o-DCB removal at 300 ℃ could be up to 95.4%. This was mainly due to the best dispersibility of the active component Mn of the catalyst prepared under this ratio, and the best redox performance.
The cobalt-iron layered double hydroxide structure carrier(CoFe-LDH) was successfully prepared by the co-precipitation method, and the active component Mn was loaded by the impregnation method and calcined to prepare the hydrotalcite-like structure catalyst MnxCoFe-LDO catalyst with different Mn loadings(Where x was the mass ratio of manganese nitrate solution to CoFe-LDH). The catalytic performance of the catalyst on nitrogen oxides(NOx) and chlorinated volatile organic compounds(CVOCs) in typical industrial exhaust gas was explored, and the catalyst was characterized by XRD, H2-TPR, NH3-TPD and TEM-EDX mapping. The results showed that the addition of Mn greatly improved the catalytic performance of CoFe-LDO. Among them, the catalyst with a mass ratio of 0.25 had the highest activity. The denitration efficiency was maintained above 90% in the test temperature range, and the efficiency of o-DCB removal at 300 ℃ could be up to 95.4%. This was mainly due to the best dispersibility of the active component Mn of the catalyst prepared under this ratio, and the best redox performance.
2022, 40(2): 14-19,41.
doi: 10.13205/j.hjgc.202202003
Abstract:
Antibiotic resistant bacteria(ARB) have been widely concerned as an emerging contaminant, but the effect of ultraviolet(UV) disinfection on ARB removal has not been fully studied. This paper focused on the disinfection of the filtered secondary effluent from a municipal sewage treatment plant, investigated the removal effect of UV disinfection on ARB and the photoreactivation and dark repair potential of ARB by analyzing the abundance of bacteria with resistance to tetracycline, ampicillin, chloramphenicol or streptomycin before and after UV disinfection. The results showed that UV could partly inactivate the ARB, and the resistance ability of the four ARB to UV disinfection followed the order of ampicillin resistant bacteria>tetracycline resistant bacteria>streptomycin resistant bacteria≈chloramphenico resistant bacteria. UV disinfection with dosage of 20 mJ/cm2 could completely inactivate chloramphenicol resistant bacteria and streptomycin resistant bacteria, and these two kinds of ARB did not appear photoreactivation or dark repair ability within 24 h post disinfection. This dosage of UV could not completely inactivate ampicillin resistant bacteria or tetracycline resistant bacteria, and the inactivated bacteria could partly reactivate with or without the light. When UV dosage reached 80 mJ/cm2, these four kinds of ARB were totally inactivated. Ampicillin resistant bacteria showed the reactivation ability within 6 h post disinfection. Whether putting in light or in dark for 24 h after disinfection, more than 70.32% of the total heterotrophic bacteria in water sample disinfected by UV were resistant to ampicillin. Therefore, UV disinfection alone could not effectively control the spread of ARB from sewage treatment plants to the environment.
Antibiotic resistant bacteria(ARB) have been widely concerned as an emerging contaminant, but the effect of ultraviolet(UV) disinfection on ARB removal has not been fully studied. This paper focused on the disinfection of the filtered secondary effluent from a municipal sewage treatment plant, investigated the removal effect of UV disinfection on ARB and the photoreactivation and dark repair potential of ARB by analyzing the abundance of bacteria with resistance to tetracycline, ampicillin, chloramphenicol or streptomycin before and after UV disinfection. The results showed that UV could partly inactivate the ARB, and the resistance ability of the four ARB to UV disinfection followed the order of ampicillin resistant bacteria>tetracycline resistant bacteria>streptomycin resistant bacteria≈chloramphenico resistant bacteria. UV disinfection with dosage of 20 mJ/cm2 could completely inactivate chloramphenicol resistant bacteria and streptomycin resistant bacteria, and these two kinds of ARB did not appear photoreactivation or dark repair ability within 24 h post disinfection. This dosage of UV could not completely inactivate ampicillin resistant bacteria or tetracycline resistant bacteria, and the inactivated bacteria could partly reactivate with or without the light. When UV dosage reached 80 mJ/cm2, these four kinds of ARB were totally inactivated. Ampicillin resistant bacteria showed the reactivation ability within 6 h post disinfection. Whether putting in light or in dark for 24 h after disinfection, more than 70.32% of the total heterotrophic bacteria in water sample disinfected by UV were resistant to ampicillin. Therefore, UV disinfection alone could not effectively control the spread of ARB from sewage treatment plants to the environment.
2022, 40(2): 20-26.
doi: 10.13205/j.hjgc.202202004
Abstract:
The self-purification of water bodies is of great significance in the study of water environment. Microorganisms are the main bearers of self-purification of water bodies. In order to study the role of microorganisms in self-purification of water bodies, this study used degradation coefficients to characterize the self-purification of water bodies to COD, ammonia nitrogen, TN and TP. To use mercury chloride inactivated microorganisms as a control group, the degradation coefficient was divided into comprehensive degradation and biological degradation. In-situ degradation coefficient calculation experiments were carried out in three characteristic sections of the Qing-Yi River, and typical sections were selected for high-throughput microbial detection. The results showed that: 1) the main groups of microorganisms in the river were the common obligate aerobic genus such as Pyricularia sp., Thermomonas sp, and a small number of genus bacteria capable of nitrification. 2) The biodegradation coefficients of COD and ammonia nitrogen were positively correlated with their comprehensive degradation coefficients, and the proportion of biodegradation was high, 78% and 42%, respectively. TN and TP had no significant relationship, indicating that COD and ammonia nitrogen were more dependent on biological self-purification than TN and TP in the river channel. 3) Through fitting the biodegradation coefficient with the comprehensive degradation coefficient, and combining the first-order kinetic degradation equation, the equation between the initial concentration and the concentration after comprehensive degradation and biological degradation was deduced.
The self-purification of water bodies is of great significance in the study of water environment. Microorganisms are the main bearers of self-purification of water bodies. In order to study the role of microorganisms in self-purification of water bodies, this study used degradation coefficients to characterize the self-purification of water bodies to COD, ammonia nitrogen, TN and TP. To use mercury chloride inactivated microorganisms as a control group, the degradation coefficient was divided into comprehensive degradation and biological degradation. In-situ degradation coefficient calculation experiments were carried out in three characteristic sections of the Qing-Yi River, and typical sections were selected for high-throughput microbial detection. The results showed that: 1) the main groups of microorganisms in the river were the common obligate aerobic genus such as Pyricularia sp., Thermomonas sp, and a small number of genus bacteria capable of nitrification. 2) The biodegradation coefficients of COD and ammonia nitrogen were positively correlated with their comprehensive degradation coefficients, and the proportion of biodegradation was high, 78% and 42%, respectively. TN and TP had no significant relationship, indicating that COD and ammonia nitrogen were more dependent on biological self-purification than TN and TP in the river channel. 3) Through fitting the biodegradation coefficient with the comprehensive degradation coefficient, and combining the first-order kinetic degradation equation, the equation between the initial concentration and the concentration after comprehensive degradation and biological degradation was deduced.
2022, 40(2): 27-33,80.
doi: 10.13205/j.hjgc.202202005
Abstract:
The indoor culture method was selected to study the toxic mechanism of AgNPs to Achromobacter denitrificans and the effects of silver nanoparticles on the growth inhibition, ammoniation, assimilation and absorption of NH4+-N, cell membrane surface structure and the accumulation of the reactive oxygen species. The study found that AgNPs could inhibit bacterial growth, and the inhibitory effect was positively related to concentration and exposure time. In the nitrification medium supplemented with 10 mg/LAgNPs, the growth inhibition rate of Achromobacter denitrificans reached 38.2% after 12 h, while the growth inhibition rate was only 11.5% when 1 mg/LAgNPs was added. Under different AgNPs exposure concentrations, the growth inhibition rates tended to be stable after 4~6 h. The biochemical activity of bacteria after exposure to AgNPs decreased. When the dosage of AgNPs increased from 1 mg/L to 10 mg/L, the NH+4-N generation rate decreased by 25.3%, from 2.77 mg/(L·h) to 2.07 mg/(L·h); NH4+-N assimilation rate decreased by 69.1%, from 5.52 mg/(L·h) to 1.71 mg/(L·h). Besides, pH was an important factor affecting the toxicity. Both weak acid(pH=5.0) and weak alkaline(pH=9.0) were not conducive to bacterial survival. Through the analysis of the mechanism of toxicity, we found that AgNPs can cause the depression and rupture of the cell membrane surface, the leakage of substances in the membrane, and the accumulation of reactive oxygen species in the cells.
The indoor culture method was selected to study the toxic mechanism of AgNPs to Achromobacter denitrificans and the effects of silver nanoparticles on the growth inhibition, ammoniation, assimilation and absorption of NH4+-N, cell membrane surface structure and the accumulation of the reactive oxygen species. The study found that AgNPs could inhibit bacterial growth, and the inhibitory effect was positively related to concentration and exposure time. In the nitrification medium supplemented with 10 mg/LAgNPs, the growth inhibition rate of Achromobacter denitrificans reached 38.2% after 12 h, while the growth inhibition rate was only 11.5% when 1 mg/LAgNPs was added. Under different AgNPs exposure concentrations, the growth inhibition rates tended to be stable after 4~6 h. The biochemical activity of bacteria after exposure to AgNPs decreased. When the dosage of AgNPs increased from 1 mg/L to 10 mg/L, the NH+4-N generation rate decreased by 25.3%, from 2.77 mg/(L·h) to 2.07 mg/(L·h); NH4+-N assimilation rate decreased by 69.1%, from 5.52 mg/(L·h) to 1.71 mg/(L·h). Besides, pH was an important factor affecting the toxicity. Both weak acid(pH=5.0) and weak alkaline(pH=9.0) were not conducive to bacterial survival. Through the analysis of the mechanism of toxicity, we found that AgNPs can cause the depression and rupture of the cell membrane surface, the leakage of substances in the membrane, and the accumulation of reactive oxygen species in the cells.
2022, 40(2): 34-41.
doi: 10.13205/j.hjgc.202202006
Abstract:
To identify Datong Lake's pollution sources and the main influencing factors, the spatial-temporal characteristics about water quality indexes of 33 sample points in Datong Lake were analyzed, based on two analytical methods(the principal component analysis and cluster analysis), and water quality assessment was carried out by two methods(single factor index method and comprehensive water quality identification method), during July to November 2019. Using single factor index method, in July 2019, Datong lake water quality was identified as Ⅴ class, and inferior Ⅴ class in August 2019. From September to November, the water quality got improved, for Ⅳ class. Using the comprehensive water quality identification method, the monthly water quality of Datong lake was in the sequence of(from good to bad): September>November>October>July>August. On the whole, water quality in Datong Lake showed a trend of getting worse. The main factors exceeding the standard were TN and TP, and it's worthy of noting that CODMn exceeded the standard in October and November. The water quality was extremely affected by the river entering the lake. In the flood season(July and August), ammonia nitrogen, SS, CODMn and TP were the main factors in the lake area, which were mainly from non-point sources such as farmland runoff, livestock and poultry breeding pollution and domestic sewage; in the non-flood season(September to November), the main factors were ammonia nitrogen, nitrate, CODMn and TP, which were mainly from domestic sewage and internal pollution, etc., affected by the joint action of multiple pollution sources.
To identify Datong Lake's pollution sources and the main influencing factors, the spatial-temporal characteristics about water quality indexes of 33 sample points in Datong Lake were analyzed, based on two analytical methods(the principal component analysis and cluster analysis), and water quality assessment was carried out by two methods(single factor index method and comprehensive water quality identification method), during July to November 2019. Using single factor index method, in July 2019, Datong lake water quality was identified as Ⅴ class, and inferior Ⅴ class in August 2019. From September to November, the water quality got improved, for Ⅳ class. Using the comprehensive water quality identification method, the monthly water quality of Datong lake was in the sequence of(from good to bad): September>November>October>July>August. On the whole, water quality in Datong Lake showed a trend of getting worse. The main factors exceeding the standard were TN and TP, and it's worthy of noting that CODMn exceeded the standard in October and November. The water quality was extremely affected by the river entering the lake. In the flood season(July and August), ammonia nitrogen, SS, CODMn and TP were the main factors in the lake area, which were mainly from non-point sources such as farmland runoff, livestock and poultry breeding pollution and domestic sewage; in the non-flood season(September to November), the main factors were ammonia nitrogen, nitrate, CODMn and TP, which were mainly from domestic sewage and internal pollution, etc., affected by the joint action of multiple pollution sources.
2022, 40(2): 42-46.
doi: 10.13205/j.hjgc.202202007
Abstract:
The microbiota contained in the aged refuse plays an important role in the treatment of leachate. In order to understand the effect of microbial community on the degradation of organic matters in leachate, 16 S rRNA gene high-throughput sequencing technology and analysis method were used to study the microbial community structure and diversity of aged refuse at different sites. The results showed that the aged refuse contained rich microbial communities, and the richness of each site was similar, but the diversity was different; each site contained Firmicutes, Euryarchaeota, Chloroflexi, Bacteroidetes, Synergistetes, Actinobacteria, Proteobacteria, Planctomycetes, Thermotogae and Atribacteria(with relative abundance of 1.0% above); Firmicutes, the dominant phyla, had the highest relative abundance at K1, K2, K3 and K4, which were 39.10%, 31.79%, 47.09% and 33.84%, respectively; the relative abundance of Euryarchaeota was higher at K1 and K2 with higher organic load of leachate and at K4 with longer hydraulic retention time, while the relative abundance was lower at K3 in the middle layer. The structure and diversity of the microbial community were related to the leachate loading, and the diversity of the microbial community was higher in the aged refuse layer with higher leachate loading. The rich microbial community in the aged refuse layer played an important role in stabilizing the physical and chemical properties of the leachate.
The microbiota contained in the aged refuse plays an important role in the treatment of leachate. In order to understand the effect of microbial community on the degradation of organic matters in leachate, 16 S rRNA gene high-throughput sequencing technology and analysis method were used to study the microbial community structure and diversity of aged refuse at different sites. The results showed that the aged refuse contained rich microbial communities, and the richness of each site was similar, but the diversity was different; each site contained Firmicutes, Euryarchaeota, Chloroflexi, Bacteroidetes, Synergistetes, Actinobacteria, Proteobacteria, Planctomycetes, Thermotogae and Atribacteria(with relative abundance of 1.0% above); Firmicutes, the dominant phyla, had the highest relative abundance at K1, K2, K3 and K4, which were 39.10%, 31.79%, 47.09% and 33.84%, respectively; the relative abundance of Euryarchaeota was higher at K1 and K2 with higher organic load of leachate and at K4 with longer hydraulic retention time, while the relative abundance was lower at K3 in the middle layer. The structure and diversity of the microbial community were related to the leachate loading, and the diversity of the microbial community was higher in the aged refuse layer with higher leachate loading. The rich microbial community in the aged refuse layer played an important role in stabilizing the physical and chemical properties of the leachate.
2022, 40(2): 47-52.
doi: 10.13205/j.hjgc.202202008
Abstract:
The secretion characteristics of extracellular polymers(EPS) and the release of acylated homoserine lactones(AHLs) were investigated under three organic loading conditions [0.29, 0.58, 1.16 kg COD/(m3·d)] in continuous flow A2/O system. The results showed that TB-EPS was the main component of EPS, which had higher molecular weight and wider molecular weight distribution. The effect of organic loading on the components of LB-EPS was greater than that of TB-EPS. The increasing trend of polysaccharide(PS) content in LB-EPS was more obvious than that of protein(PN) with the increase of organic loading, making the sludge system have stronger settling property under high organic loading. The content and species of AHLs under different organic loads were significantly different. C10-HSL, C12-HSL and C14-HSL were dominant in sludge system. The correlation between AHLs and LB-EPS was weak, and there were significant or strong correlations between many types of AHLs and TB-EPS, which provided theoretical support for AHLs regulating EPS synthesis to achieve stable operation of the system.
The secretion characteristics of extracellular polymers(EPS) and the release of acylated homoserine lactones(AHLs) were investigated under three organic loading conditions [0.29, 0.58, 1.16 kg COD/(m3·d)] in continuous flow A2/O system. The results showed that TB-EPS was the main component of EPS, which had higher molecular weight and wider molecular weight distribution. The effect of organic loading on the components of LB-EPS was greater than that of TB-EPS. The increasing trend of polysaccharide(PS) content in LB-EPS was more obvious than that of protein(PN) with the increase of organic loading, making the sludge system have stronger settling property under high organic loading. The content and species of AHLs under different organic loads were significantly different. C10-HSL, C12-HSL and C14-HSL were dominant in sludge system. The correlation between AHLs and LB-EPS was weak, and there were significant or strong correlations between many types of AHLs and TB-EPS, which provided theoretical support for AHLs regulating EPS synthesis to achieve stable operation of the system.
2022, 40(2): 53-58,153.
doi: 10.13205/j.hjgc.202202009
Abstract:
In order to study the form and distribution characteristics of nitrogen in the sediments of Baiyangdian Lake in summer and autumn, the sediment nitrogen was classified into ion exchangeable form nitrogen(IEF-N), weak acid extractable form nitrogen(WAEF-N), strong alkali extractable form nitrogen(SAEF-N) and strong oxidant extractable form nitrogen(SOEF-N), by the method of extraction step by step. Meanwhile, the relationship between sediment nitrogen and interstitial water was also investigated. The results showed that the total nitrogen content of the sediments ranged from 3195.95~6335.34 mg/kg in summer and 3553.89~5786.3 mg/kg in autumn. The difference of total nitrogen content between original area and cultured area was the largest in summer and autumn. In the 15 sampling sites and 5 functional areas in summer and autumn, the orders of contents of all nitrogen forms were WAEF-N> SOEF-N>SAEF-N>IEF-N. Correlation analysis showed that ammonia and nitrate nitrogen of WAEF in sediments had significant correlation with ammonia nitrogen and nitrate nitrogen in pore water in summer and autumn(P<0.05). The study on nitrogen form in surface sediments of Baiyangdian Lake can provide a theoretical basis for lake management.
In order to study the form and distribution characteristics of nitrogen in the sediments of Baiyangdian Lake in summer and autumn, the sediment nitrogen was classified into ion exchangeable form nitrogen(IEF-N), weak acid extractable form nitrogen(WAEF-N), strong alkali extractable form nitrogen(SAEF-N) and strong oxidant extractable form nitrogen(SOEF-N), by the method of extraction step by step. Meanwhile, the relationship between sediment nitrogen and interstitial water was also investigated. The results showed that the total nitrogen content of the sediments ranged from 3195.95~6335.34 mg/kg in summer and 3553.89~5786.3 mg/kg in autumn. The difference of total nitrogen content between original area and cultured area was the largest in summer and autumn. In the 15 sampling sites and 5 functional areas in summer and autumn, the orders of contents of all nitrogen forms were WAEF-N> SOEF-N>SAEF-N>IEF-N. Correlation analysis showed that ammonia and nitrate nitrogen of WAEF in sediments had significant correlation with ammonia nitrogen and nitrate nitrogen in pore water in summer and autumn(P<0.05). The study on nitrogen form in surface sediments of Baiyangdian Lake can provide a theoretical basis for lake management.
2022, 40(2): 59-65,198.
doi: 10.13205/j.hjgc.202202010
Abstract:
The contradiction between the supply and demand of water resources of the islands has become increasingly prominent. This study comprehensively used geophysical prospecting, hydrogeological drilling and isotopes tracing analysis to evaluate the storability and reproducibility of groundwater resources in the Tuichuanwan reservoir area of Wanshan Island, Zhuhai, in Guangdong Province. The hydrogeological structure of the Tuichuanwan reservoir area were revealed by the methods of high-density resistivity and the hydrogeological drillings, and we found that the loose sediment aquifer was spatially discontinuous, which together with the fractured aquifer, constituted the main groundwater aquifer in the area. And the bedrock layer constituted the water-proof floor. The permeability coefficient of the loose sedimentary aquifer was 8.30×10-3 cm/s and the specific yield was 0.32; the permeability coefficient of the fractured aquifer was 2.52×10-5 cm/s and the specific yield was 0.10. The groundwater storage capacity of the aquifer was approximately 14,873 m3, indicating a large water storage space. Precipitation was found to be the main source of groundwater using isotopes tracing. The recharge was determined to be 145,065 m3/a through runoff segmentation, and the renewal cycle of groundwater was about 37 d, indicating that the groundwater in the reservoir was reproducible and had an excellent recharge condition. This paper could provide technical ideas and references for exploration and management of groundwater resources in granite islands.
The contradiction between the supply and demand of water resources of the islands has become increasingly prominent. This study comprehensively used geophysical prospecting, hydrogeological drilling and isotopes tracing analysis to evaluate the storability and reproducibility of groundwater resources in the Tuichuanwan reservoir area of Wanshan Island, Zhuhai, in Guangdong Province. The hydrogeological structure of the Tuichuanwan reservoir area were revealed by the methods of high-density resistivity and the hydrogeological drillings, and we found that the loose sediment aquifer was spatially discontinuous, which together with the fractured aquifer, constituted the main groundwater aquifer in the area. And the bedrock layer constituted the water-proof floor. The permeability coefficient of the loose sedimentary aquifer was 8.30×10-3 cm/s and the specific yield was 0.32; the permeability coefficient of the fractured aquifer was 2.52×10-5 cm/s and the specific yield was 0.10. The groundwater storage capacity of the aquifer was approximately 14,873 m3, indicating a large water storage space. Precipitation was found to be the main source of groundwater using isotopes tracing. The recharge was determined to be 145,065 m3/a through runoff segmentation, and the renewal cycle of groundwater was about 37 d, indicating that the groundwater in the reservoir was reproducible and had an excellent recharge condition. This paper could provide technical ideas and references for exploration and management of groundwater resources in granite islands.
2022, 40(2): 66-70.
doi: 10.13205/j.hjgc.202202011
Abstract:
In order to understand the current situation of water quality of dam-controlled scenic river in urban area, four urban dam-controlled scenic rivers in Guanzhong section of Weihe River Basin were investigated in January, April, August and November, 2018. Based on the status of water quality index(WQI) and trophic level index(TLI), the water quality and eutrophication status of the four urban dam-controlled scenic rivers were evaluated. The results showed that the average value of WQI of the four urban dam-controlled scenic rivers was 47.65~56.18, and the water quality was generally classified as moderate to low; the average value of TLI was 61.50~66.42, and the nutritional status was classified as moderate eutrophication. There was a significant negative correlation between WQI and TLI(r=-0.771, P<0.001). Based on the evaluation results, the water quality of dam-controlled scenic river in Guanzhong section of Weihe River was relatively better and the nutrient level was lower in winter and spring; in summer and autumn, the water quality was lower and the nutrition level was higher.
In order to understand the current situation of water quality of dam-controlled scenic river in urban area, four urban dam-controlled scenic rivers in Guanzhong section of Weihe River Basin were investigated in January, April, August and November, 2018. Based on the status of water quality index(WQI) and trophic level index(TLI), the water quality and eutrophication status of the four urban dam-controlled scenic rivers were evaluated. The results showed that the average value of WQI of the four urban dam-controlled scenic rivers was 47.65~56.18, and the water quality was generally classified as moderate to low; the average value of TLI was 61.50~66.42, and the nutritional status was classified as moderate eutrophication. There was a significant negative correlation between WQI and TLI(r=-0.771, P<0.001). Based on the evaluation results, the water quality of dam-controlled scenic river in Guanzhong section of Weihe River was relatively better and the nutrient level was lower in winter and spring; in summer and autumn, the water quality was lower and the nutrition level was higher.
2022, 40(2): 71-80.
doi: 10.13205/j.hjgc.202202012
Abstract:
In order to study the characteristics and sources of carbon components in PM2.5 in Beijing and its surrounding areas in summer after the implementation of the Three-year Plan on Defending the Blue Sky and other policies, samples were collected at sites in Beijing urban area and Hebei suburban area in July 2019. The organic carbon(OC), elemental carbon(EC) and their components concentrations were determined using a thermo-optical carbon analyzer. The concentrations of secondary organic carbon(SOC) were also estimated by the OC/EC minimum ratio method and the minimum R squared method. The sources of carbon aerosols were analyzed by principal component analysis and back-trajectory analysis. The results showed that the average concentrations of OC and EC in PM2.5 were(6.34±0.64) μg/m3 and(1.96±0.29) μg/m3 in Beijing urban area, accounting for 18.65% and 5.78% of PM2.5, respectively. The average concentrations of OC and EC were(6.29±0.79) μg/m3 and(3.54±0.63) μg/m3 in Hebei suburban area, accounting for 17.69% and 9.53% of PM2.5, respectively. The values of SOC in Beijing urban area were(3.35±0.59) μg/m3 and 3.98 μg/m3, respectively, accounting for(51.77±6.97)% and 68.48% of total OC concentration. The values of SOC in Hebei suburban area were(3.28±0.69) μg/m3 and 4.17 μg/m3, respectively, accounting for(62.42±9.62)% and 68.32% of total OC concentration. There was severe secondary pollution in Beijing urban area and Hebei suburban area in summer. Mixed vehicle emissions, road dust and combustion sources were the primary pollution sources of carbon aerosols in Beijing urban area. Industrial coal emission, vehicle exhaust and dust were the main pollution sources of carbon aerosols in Hebei suburban area. Back-trajectory analysis showed that the air mass trajectories in summer mainly came from southeast, southwest and south direction, which had a significant impact on carbon components of PM2.5 in the urban area of Beijing and the suburban area of Hebei.
In order to study the characteristics and sources of carbon components in PM2.5 in Beijing and its surrounding areas in summer after the implementation of the Three-year Plan on Defending the Blue Sky and other policies, samples were collected at sites in Beijing urban area and Hebei suburban area in July 2019. The organic carbon(OC), elemental carbon(EC) and their components concentrations were determined using a thermo-optical carbon analyzer. The concentrations of secondary organic carbon(SOC) were also estimated by the OC/EC minimum ratio method and the minimum R squared method. The sources of carbon aerosols were analyzed by principal component analysis and back-trajectory analysis. The results showed that the average concentrations of OC and EC in PM2.5 were(6.34±0.64) μg/m3 and(1.96±0.29) μg/m3 in Beijing urban area, accounting for 18.65% and 5.78% of PM2.5, respectively. The average concentrations of OC and EC were(6.29±0.79) μg/m3 and(3.54±0.63) μg/m3 in Hebei suburban area, accounting for 17.69% and 9.53% of PM2.5, respectively. The values of SOC in Beijing urban area were(3.35±0.59) μg/m3 and 3.98 μg/m3, respectively, accounting for(51.77±6.97)% and 68.48% of total OC concentration. The values of SOC in Hebei suburban area were(3.28±0.69) μg/m3 and 4.17 μg/m3, respectively, accounting for(62.42±9.62)% and 68.32% of total OC concentration. There was severe secondary pollution in Beijing urban area and Hebei suburban area in summer. Mixed vehicle emissions, road dust and combustion sources were the primary pollution sources of carbon aerosols in Beijing urban area. Industrial coal emission, vehicle exhaust and dust were the main pollution sources of carbon aerosols in Hebei suburban area. Back-trajectory analysis showed that the air mass trajectories in summer mainly came from southeast, southwest and south direction, which had a significant impact on carbon components of PM2.5 in the urban area of Beijing and the suburban area of Hebei.
2022, 40(2): 81-87.
doi: 10.13205/j.hjgc.202202013
Abstract:
In this paper, the mixture of fly ash and carbide slag(FC) was used as the carrier, Na2O as the active component, and the adsorbent x% Na2O/FC(x% represents the mass ratio of active component Na2O in the adsorbent) was prepared by ultrasonic impregnation method. The adsorbents were characterized by XRD, BET and SEM, and the mechanism of simultaneous desulfurization and denitration of adsorbents under microwave radiation was discussed. The results showed that Na2O loading under microwave significantly improved the performance of the adsorbent. Simultaneous desulfurization and denitrification performance of 6%Na2O/FC was the best. The desulfurization t90% and t50%(tx% was the reaction time when the desulfurization rate of adsorbents or the denitrification rate reached x%) were 12 min and 73 min, and the denitrification t90% and t50% were 4 min and 16 min. The mechanism analysis showed that the simultaneous desulfurization and denitration process was dominated by physical adsorption at first, and chemical adsorption after a period of reaction. The chemisorption process of Na2O/FC adsorbent under microwave was found as follows: SO2 and NO were oxidized into SO3 and N2O5 by active oxygen species, and SO3 and N2O5 reacted with metal oxides to generate sulfates and nitrates such as Ca5(SiO4)2SO4,(MgxCa1-x)(NO3)2 and CaSO4. At the same time, the active component Na2O directly reacted with the adsorbed SO2 and NO to form Na2SO3 and NaNO3.
In this paper, the mixture of fly ash and carbide slag(FC) was used as the carrier, Na2O as the active component, and the adsorbent x% Na2O/FC(x% represents the mass ratio of active component Na2O in the adsorbent) was prepared by ultrasonic impregnation method. The adsorbents were characterized by XRD, BET and SEM, and the mechanism of simultaneous desulfurization and denitration of adsorbents under microwave radiation was discussed. The results showed that Na2O loading under microwave significantly improved the performance of the adsorbent. Simultaneous desulfurization and denitrification performance of 6%Na2O/FC was the best. The desulfurization t90% and t50%(tx% was the reaction time when the desulfurization rate of adsorbents or the denitrification rate reached x%) were 12 min and 73 min, and the denitrification t90% and t50% were 4 min and 16 min. The mechanism analysis showed that the simultaneous desulfurization and denitration process was dominated by physical adsorption at first, and chemical adsorption after a period of reaction. The chemisorption process of Na2O/FC adsorbent under microwave was found as follows: SO2 and NO were oxidized into SO3 and N2O5 by active oxygen species, and SO3 and N2O5 reacted with metal oxides to generate sulfates and nitrates such as Ca5(SiO4)2SO4,(MgxCa1-x)(NO3)2 and CaSO4. At the same time, the active component Na2O directly reacted with the adsorbed SO2 and NO to form Na2SO3 and NaNO3.
2022, 40(2): 88-92,99.
doi: 10.13205/j.hjgc.202202014
Abstract:
This research proposed a green method for recovering positive active substances from spent lithium cobalt oxide batteries, used tartaric acid as the leaching agent and reducing agent to recover cobalt and lithium. The results showed that the leaching rates of cobalt and lithium were 92.95% and 91.86% respectively, when the molar ratio of lithium cobalt oxide to tartaric acid was 1∶4, the solid-liquid ratio was 15 g/L, the reaction temperature was 90 ℃ and the reaction time was 5 h. Kinetic analysis showed that the leaching reactions of Co and Li could be fitted best by the classical model. And their apparent activation energies were 55.20 kJ/mol and 63.65 kJ/mol respectively, which belonged to endothermic reaction and chemical reaction control. This process can achieve the efficient and green way by recovering waste lithium cobalt oxide cathode materials, and provide a theoretical basis for the recovery of other waste lithium-ion batteries.
This research proposed a green method for recovering positive active substances from spent lithium cobalt oxide batteries, used tartaric acid as the leaching agent and reducing agent to recover cobalt and lithium. The results showed that the leaching rates of cobalt and lithium were 92.95% and 91.86% respectively, when the molar ratio of lithium cobalt oxide to tartaric acid was 1∶4, the solid-liquid ratio was 15 g/L, the reaction temperature was 90 ℃ and the reaction time was 5 h. Kinetic analysis showed that the leaching reactions of Co and Li could be fitted best by the classical model. And their apparent activation energies were 55.20 kJ/mol and 63.65 kJ/mol respectively, which belonged to endothermic reaction and chemical reaction control. This process can achieve the efficient and green way by recovering waste lithium cobalt oxide cathode materials, and provide a theoretical basis for the recovery of other waste lithium-ion batteries.
2022, 40(2): 93-99.
doi: 10.13205/j.hjgc.202202015
Abstract:
The weight loss and heavy metal distribution in fly ash from incineration of a cadmium(Cd) and zinc(Zn) hyperaccumulation plant, Sedum plumbizincicola were studied in a fluidized bed incinerator and a thermogravimetric analyzer. Meanwhile, the basic characteristics including particle distribution, microscopic morphology and leaching toxicity of cyclone ash and bag filter ash under different incineration temperatures were compared, to provide data support for the further disposal and resource utilization of incineration products. The results showed that the weight loss of S. plumbizincicola during incineration could be divided into three periods: moisture evaporation, fast decomposition, and fixed carbon combustion. The particle size distribution patterns of cyclone ash and bag filter ash both followed a normal distribution, and the particle size in bag filter ash was smaller. Complex and diverse microscopic morphology of the two fly ashes was found, with mostly rod-shaped, small spherical, irregular polymer and honeycomb porous structure. Metal(Cd, Zn and Pb) concentrations in the fly ashes firstly increased and then decreased with the increasing temperature, and reached maximum values at 800 ℃. In addition, the TCLP leaching toxicity of metals in the two fly ashes far exceeded the standard limit, indicating high leaching risk in environment.
The weight loss and heavy metal distribution in fly ash from incineration of a cadmium(Cd) and zinc(Zn) hyperaccumulation plant, Sedum plumbizincicola were studied in a fluidized bed incinerator and a thermogravimetric analyzer. Meanwhile, the basic characteristics including particle distribution, microscopic morphology and leaching toxicity of cyclone ash and bag filter ash under different incineration temperatures were compared, to provide data support for the further disposal and resource utilization of incineration products. The results showed that the weight loss of S. plumbizincicola during incineration could be divided into three periods: moisture evaporation, fast decomposition, and fixed carbon combustion. The particle size distribution patterns of cyclone ash and bag filter ash both followed a normal distribution, and the particle size in bag filter ash was smaller. Complex and diverse microscopic morphology of the two fly ashes was found, with mostly rod-shaped, small spherical, irregular polymer and honeycomb porous structure. Metal(Cd, Zn and Pb) concentrations in the fly ashes firstly increased and then decreased with the increasing temperature, and reached maximum values at 800 ℃. In addition, the TCLP leaching toxicity of metals in the two fly ashes far exceeded the standard limit, indicating high leaching risk in environment.
2022, 40(2): 100-105,112.
doi: 10.13205/j.hjgc.202202016
Abstract:
Mechanochemical methods were used to remediate polycyclic aromatic hydrocarbons(PAHs) contaminated soil. The effects of ball-milling time and ball-milling speed on the removal rate of pyrene in soil were studied. When the milling time was 6 h and the milling speed was 500 r/min, the removal rate of pyrene in the soil was 93.78%. The synthetic soil samples using SiO2 before and after ball milling were analyzed by GC-MS, FT-IR spectra and Raman spectra. The degradation pathway and mechanism of pyrene were revealed as follows: the benzene rings of pyrene were destroyed, and some of the intermediate products were PAHs with fewer benzene rings and alkanes with shorter carbon chains, and some were carbonized into graphite and amorphous carbon. The residual concentration of pyrene and fluoranthene in soil was 21.45, 35.68 mg/kg when the site contaminated soil was remediation by mechanochemical method. Mechanochemical method provides a possible method and considerable application prospect in remediation of PAHs contaminated soil.
Mechanochemical methods were used to remediate polycyclic aromatic hydrocarbons(PAHs) contaminated soil. The effects of ball-milling time and ball-milling speed on the removal rate of pyrene in soil were studied. When the milling time was 6 h and the milling speed was 500 r/min, the removal rate of pyrene in the soil was 93.78%. The synthetic soil samples using SiO2 before and after ball milling were analyzed by GC-MS, FT-IR spectra and Raman spectra. The degradation pathway and mechanism of pyrene were revealed as follows: the benzene rings of pyrene were destroyed, and some of the intermediate products were PAHs with fewer benzene rings and alkanes with shorter carbon chains, and some were carbonized into graphite and amorphous carbon. The residual concentration of pyrene and fluoranthene in soil was 21.45, 35.68 mg/kg when the site contaminated soil was remediation by mechanochemical method. Mechanochemical method provides a possible method and considerable application prospect in remediation of PAHs contaminated soil.
2022, 40(2): 106-112.
doi: 10.13205/j.hjgc.202202017
Abstract:
The physicochemical properties of four kinds of textile dyeing sludge were investigated, including the levels of metal, nonmetal, organic matter and 16 polycyclic aromatic hydrocarbons(Σ16PAHs). Furthermore, the relationship between the degradation efficiency of PAHs after the treatment of ultrasonic Fenton technology(US-Fenton) and the physicochemical properties of the sludge were discussed. The results showed that the concentration of Σ16PAHs in sludge was 983.52~2942.34 ng/g, and that of the low molecular weight PAHs was 570.47~1919.97 ng/g, which was the main component of Σ16PAHs, accounting for more than 50% by mass weight. After the US-Fenton treatment, the degradation rate of Σ16PAHs was 35.24%~61.80% and the degradation rate of lower molecular weight PAHs was higher than that of the higher molecular weight PAHs, about 28.22%~40.48% and 11.76%~24.04%, respectively. The results indicated that the characteristics of the sludge had a great impact on the degradation of PAHs, among which, C, Fe and organic matter content had a negative correlation with the degradation of PAHs, respectively. Ca content in sludge had a positive correlation with the degradation rate of PAHs. And their correlation coefficient R2 were all more than 0.90. This study would provide a theoretical basis for the degradation of PAHs and other organic pollutants in sludge by US-Fenton.
The physicochemical properties of four kinds of textile dyeing sludge were investigated, including the levels of metal, nonmetal, organic matter and 16 polycyclic aromatic hydrocarbons(Σ16PAHs). Furthermore, the relationship between the degradation efficiency of PAHs after the treatment of ultrasonic Fenton technology(US-Fenton) and the physicochemical properties of the sludge were discussed. The results showed that the concentration of Σ16PAHs in sludge was 983.52~2942.34 ng/g, and that of the low molecular weight PAHs was 570.47~1919.97 ng/g, which was the main component of Σ16PAHs, accounting for more than 50% by mass weight. After the US-Fenton treatment, the degradation rate of Σ16PAHs was 35.24%~61.80% and the degradation rate of lower molecular weight PAHs was higher than that of the higher molecular weight PAHs, about 28.22%~40.48% and 11.76%~24.04%, respectively. The results indicated that the characteristics of the sludge had a great impact on the degradation of PAHs, among which, C, Fe and organic matter content had a negative correlation with the degradation of PAHs, respectively. Ca content in sludge had a positive correlation with the degradation rate of PAHs. And their correlation coefficient R2 were all more than 0.90. This study would provide a theoretical basis for the degradation of PAHs and other organic pollutants in sludge by US-Fenton.
2022, 40(2): 113-119.
doi: 10.13205/j.hjgc.202202018
Abstract:
Pyrolysis and gasification technology, as a harmless treatment method of MSW, has great research significance. The MSW fixed-bed pyrolysis and gasification model was established using Aspen Plus software. The effects of gasification temperature, gasification pressure and air equivalent ratio on the pyrolysis and gasification process of MSW were discussed based on model verification. The quadratic regression orthogonal test method was used to obtain the mathematical relationship between gas yield, gas calorific value, gasification efficiency and process parameters. Matlab software was applied to solve the equation and get the best combination of process parameters. The results showed that with the increase of gasification temperature, the calorific value of gas production increased slightly, and the produced gas yield and gasification efficiency both increased first and then tended to be stable. The air equivalent ratio had the most significant influence on the gasification efficiency, followed by the gasification temperature, and then influence of gasification pressure. When the gasification temperature was 891 ℃, the gasification pressure was 1.01×105 Pa, and the air equivalent ratio was 0.2, the gasification efficiency reached a maximum.
Pyrolysis and gasification technology, as a harmless treatment method of MSW, has great research significance. The MSW fixed-bed pyrolysis and gasification model was established using Aspen Plus software. The effects of gasification temperature, gasification pressure and air equivalent ratio on the pyrolysis and gasification process of MSW were discussed based on model verification. The quadratic regression orthogonal test method was used to obtain the mathematical relationship between gas yield, gas calorific value, gasification efficiency and process parameters. Matlab software was applied to solve the equation and get the best combination of process parameters. The results showed that with the increase of gasification temperature, the calorific value of gas production increased slightly, and the produced gas yield and gasification efficiency both increased first and then tended to be stable. The air equivalent ratio had the most significant influence on the gasification efficiency, followed by the gasification temperature, and then influence of gasification pressure. When the gasification temperature was 891 ℃, the gasification pressure was 1.01×105 Pa, and the air equivalent ratio was 0.2, the gasification efficiency reached a maximum.
2022, 40(2): 120-126.
doi: 10.13205/j.hjgc.202202019
Abstract:
Biological oxidation of methane(CH4) by CH4-oxidizing bacteria in landfill cover soil(LCS) is the most important natural way to reduce CH4 emission at landfills; however, the CH4 oxidation capacity of the traditional LCS is usually insufficient. Studies showed that biochar can be used to enhance the CH4 oxidation performance of LCS. Simultaneously, biochar also presents good adsorption and conversion of hydrogen sulfide(H2S) in landfill gas, owning potential impact on CH4 oxidation, which needs to be further investigated and revealed. Based on previous experiments, this study designed and adopted a biochar-amended LCS, inoculated it with enriched methane-oxidizing bacteria solution, and then carried out four-cycle CH4 oxidation incubation experiments under four H2S concentration conditions(0, 0.01%, 0.025% and 0.1% by volume). The results showed that as H2S concentration increased, the CH4 oxidation capacity first decreased, then increased, and finally decreased. Under 0.01% H2S, CH4 oxidation decreased slightly by 11.5%; while under 0.025% H2S, CH4 oxidation increased by 17.0%. However, 0.1% H2S obviously inhibited CH4 oxidation and reduced it by 28.8%. Combining the results of CH4 oxidation and the changes in the physical and chemical properties of the soil, it was inferred that the increase of CH4 oxidation capacity was attributed to the positive stimulation of methane monooxygenase at a low concentration of H2S around 0.025%. While high H2S concentration exhibited a significant inhibition of CH4 oxidation, due to its microbial toxicity and possible oxygen competition during the adsorption and oxidation process.
Biological oxidation of methane(CH4) by CH4-oxidizing bacteria in landfill cover soil(LCS) is the most important natural way to reduce CH4 emission at landfills; however, the CH4 oxidation capacity of the traditional LCS is usually insufficient. Studies showed that biochar can be used to enhance the CH4 oxidation performance of LCS. Simultaneously, biochar also presents good adsorption and conversion of hydrogen sulfide(H2S) in landfill gas, owning potential impact on CH4 oxidation, which needs to be further investigated and revealed. Based on previous experiments, this study designed and adopted a biochar-amended LCS, inoculated it with enriched methane-oxidizing bacteria solution, and then carried out four-cycle CH4 oxidation incubation experiments under four H2S concentration conditions(0, 0.01%, 0.025% and 0.1% by volume). The results showed that as H2S concentration increased, the CH4 oxidation capacity first decreased, then increased, and finally decreased. Under 0.01% H2S, CH4 oxidation decreased slightly by 11.5%; while under 0.025% H2S, CH4 oxidation increased by 17.0%. However, 0.1% H2S obviously inhibited CH4 oxidation and reduced it by 28.8%. Combining the results of CH4 oxidation and the changes in the physical and chemical properties of the soil, it was inferred that the increase of CH4 oxidation capacity was attributed to the positive stimulation of methane monooxygenase at a low concentration of H2S around 0.025%. While high H2S concentration exhibited a significant inhibition of CH4 oxidation, due to its microbial toxicity and possible oxygen competition during the adsorption and oxidation process.
2022, 40(2): 127-131,138.
doi: 10.13205/j.hjgc.202202020
Abstract:
Microwave-thermogravimetric reaction device was used to conduct microwave thermal desorption test for insulating oil contaminated soil. The desorption efficiency of insulating oil and the weightlessness rule of contaminated soil were investigated at different temperatures. Based on this, the composition and distribution of residual insulating oil in soil were analyzed. The results showed that when the temperature was above 400 ℃, the removal efficiency of insulating oil in soil was better, and the removal rate of insulating oil could reach 98.6%, which met the requirements of soil remediation. With the increase of temperature, the oil-bearing soil mainly experienced the stages of moisture volatilization, volatile organic compounds and volatile organic compounds. At the stage of 100~200 ℃, moisture and some low volatile organic compounds in the soil were mainly precipitated. At the stage of 400~500 ℃, the insulating oil in the soil was mainly precipitated. The main components of insulating oil in soil were C12—C21 alkanes and 5~6 cyclic aromatic hydrocarbons. When the temperature reached 400 ℃, each component of insulating oil was gradually desorbed completely. Considering the principles of desorption efficiency and economy, the appropriate desorption temperature for insulating oil contaminated soil was between 400 ℃ and 450 ℃.
Microwave-thermogravimetric reaction device was used to conduct microwave thermal desorption test for insulating oil contaminated soil. The desorption efficiency of insulating oil and the weightlessness rule of contaminated soil were investigated at different temperatures. Based on this, the composition and distribution of residual insulating oil in soil were analyzed. The results showed that when the temperature was above 400 ℃, the removal efficiency of insulating oil in soil was better, and the removal rate of insulating oil could reach 98.6%, which met the requirements of soil remediation. With the increase of temperature, the oil-bearing soil mainly experienced the stages of moisture volatilization, volatile organic compounds and volatile organic compounds. At the stage of 100~200 ℃, moisture and some low volatile organic compounds in the soil were mainly precipitated. At the stage of 400~500 ℃, the insulating oil in the soil was mainly precipitated. The main components of insulating oil in soil were C12—C21 alkanes and 5~6 cyclic aromatic hydrocarbons. When the temperature reached 400 ℃, each component of insulating oil was gradually desorbed completely. Considering the principles of desorption efficiency and economy, the appropriate desorption temperature for insulating oil contaminated soil was between 400 ℃ and 450 ℃.
2022, 40(2): 132-138.
doi: 10.13205/j.hjgc.202202021
Abstract:
In order to explore the pollution degree of heavy metals in the soil left by an abandoned pesticide factory, and analyze the remediation effect of calcination, this study collected the contaminated soil from an abandoned pesticide factory in Zhejiang Province, and used XRF analyzer to determine the total amount and available contents of heavy metals elements in the soil, discussed the characteristics of heavy metal pollution in the soil. Then the contaminated soil was repaired by calcination, and effect of roasting was evaluated based on potential ecological hazard index method. The results showed that the heavy metal pollution in the site was mainly composed of Zn, Cu, Co, Cr, V and Pb, in which the total and available contents of Zn, V and Pb were lower than the background value of Jinqu basin in Zhejiang Province, while the total and available contents of Cu, Co and Cr all exceeded the background values. The potential ecological risk assessment results based on the available contents of heavy metal showed that the site have reached the fourth level of ecological hazard(very strong). The results of calcination showed that the optimum roasting condition was roasting temperature of 400 ℃ for 1 h. Under this condition, the degree of ecological risk coefficient corresponding to Cu and Cr elements was significantly reduced, and the potential ecological risk assessment results were reduced to the second level(medium). The contaminated site reached a lower harm degree, but further repairing methods were needed to repair the impact of Co on environment. As a simple and efficient remediation technology, calcination can be used not only as a conventional remediation method, but also as an emergency remediation measure for heavy metal contaminated soil.
In order to explore the pollution degree of heavy metals in the soil left by an abandoned pesticide factory, and analyze the remediation effect of calcination, this study collected the contaminated soil from an abandoned pesticide factory in Zhejiang Province, and used XRF analyzer to determine the total amount and available contents of heavy metals elements in the soil, discussed the characteristics of heavy metal pollution in the soil. Then the contaminated soil was repaired by calcination, and effect of roasting was evaluated based on potential ecological hazard index method. The results showed that the heavy metal pollution in the site was mainly composed of Zn, Cu, Co, Cr, V and Pb, in which the total and available contents of Zn, V and Pb were lower than the background value of Jinqu basin in Zhejiang Province, while the total and available contents of Cu, Co and Cr all exceeded the background values. The potential ecological risk assessment results based on the available contents of heavy metal showed that the site have reached the fourth level of ecological hazard(very strong). The results of calcination showed that the optimum roasting condition was roasting temperature of 400 ℃ for 1 h. Under this condition, the degree of ecological risk coefficient corresponding to Cu and Cr elements was significantly reduced, and the potential ecological risk assessment results were reduced to the second level(medium). The contaminated site reached a lower harm degree, but further repairing methods were needed to repair the impact of Co on environment. As a simple and efficient remediation technology, calcination can be used not only as a conventional remediation method, but also as an emergency remediation measure for heavy metal contaminated soil.
2022, 40(2): 139-145,205.
doi: 10.13205/j.hjgc.202202022
Abstract:
The soil of 147.3 hm2 agricultural land in a lead-zinc mining area in Southeast Hubei Province was studied, through field sampling and laboratory test. The contents of heavy metals Cu, Cr, Ni, Zn, Pb, Cd, As and Hg in soil were evaluated. The results showed that: The over-standard rates of Cu, Zn, Pb, Cd and As were 33.7%, 49.0%, 73.5%, 95.9% and 85.7%, respectively. The order of single factor pollution index was Cd>As>Pb>Zn>Cu; through the Nemerow Comprehensive Pollution Index evaluation, the proportion of severe pollution, moderate pollution and slight pollution was 59.18%, 12.24% and 27.55%, respectively. Through the comprehensive index combined soil environmental quality and agricultural products quality, most of the soil of agricultural land in the lead-zinc mining area was heavily polluted(IICQS>5), which was consistent with the regional distribution of Pb, Cd and As. However, most of the agricultural products were clean or slightly polluted(IICQAP<2), and there was no obvious law in distribution of the over-standard points. There was no significant correlation between IICQs and IICQap. The distribution of IICQ value and IICQs value was consistent. Average IICQ of agricultural land in the study area was 7.84, which was heavily polluted. Combined with field investigation and data analysis, the conceptual model of soil pollution in the lead-zinc mining area was preliminarily conceived. According to Technical Guide for the Classification of Soil Environmental Quality of Agricultural Land, combined with the survey result on agricultural products, the cultivated land in the agricultural land in the lead-zinc mining area was divided into priority protection type Ⅱ(21.4 hm2), safe use type Ⅰ(57.8 hm2), safe use type wasteland(29 hm2), safe use type Ⅱ(1.2 hm2) and strict control type(37.9 hm2).
The soil of 147.3 hm2 agricultural land in a lead-zinc mining area in Southeast Hubei Province was studied, through field sampling and laboratory test. The contents of heavy metals Cu, Cr, Ni, Zn, Pb, Cd, As and Hg in soil were evaluated. The results showed that: The over-standard rates of Cu, Zn, Pb, Cd and As were 33.7%, 49.0%, 73.5%, 95.9% and 85.7%, respectively. The order of single factor pollution index was Cd>As>Pb>Zn>Cu; through the Nemerow Comprehensive Pollution Index evaluation, the proportion of severe pollution, moderate pollution and slight pollution was 59.18%, 12.24% and 27.55%, respectively. Through the comprehensive index combined soil environmental quality and agricultural products quality, most of the soil of agricultural land in the lead-zinc mining area was heavily polluted(IICQS>5), which was consistent with the regional distribution of Pb, Cd and As. However, most of the agricultural products were clean or slightly polluted(IICQAP<2), and there was no obvious law in distribution of the over-standard points. There was no significant correlation between IICQs and IICQap. The distribution of IICQ value and IICQs value was consistent. Average IICQ of agricultural land in the study area was 7.84, which was heavily polluted. Combined with field investigation and data analysis, the conceptual model of soil pollution in the lead-zinc mining area was preliminarily conceived. According to Technical Guide for the Classification of Soil Environmental Quality of Agricultural Land, combined with the survey result on agricultural products, the cultivated land in the agricultural land in the lead-zinc mining area was divided into priority protection type Ⅱ(21.4 hm2), safe use type Ⅰ(57.8 hm2), safe use type wasteland(29 hm2), safe use type Ⅱ(1.2 hm2) and strict control type(37.9 hm2).
2022, 40(2): 146-153.
doi: 10.13205/j.hjgc.202202023
Abstract:
A 60000 m3/h regenerative thermal oxidizer(RTO) was used to treat the VOCs exhaust from industrial sources. It was found that the residence time of exhaust in the RTO was insufficient during the RTO was running. The concentration of VOCs in the purified gas fluctuated greatly. Numerical simulation of flow field of the RTO showed that the structure design of combustion chamber of the RTO was unreasonable. In order to solve this problem, in this work, the structure of the combustion chamber was optimized by numerical simulation. RTO design and improvement parameters were determined and applied. Inclined plates and retaining walls were installed in the combustion chamber of the RTO. The narrowed channels of the combustion chamber were extended. The results of the simulation and practical application showed that the structure optimization could effectively improve the uniformity of the flow field distribution at the inlet side of the combustion chamber. The overall turbulence kinetic energy in the combustion chamber was increased. The high temperature area in the combustion chamber was expanded. The fluctuation of the VOCs concentration of the purified gas was greatly reduced in practical optimized operation. The concentration differences between different operation stages were reduced by 78%, as low as about 4 mg/m3. In addition, the removal efficiency(RE) of VOCs remained above 99.5%. The highly efficient purification of industrial VOCs exhaust was realized through the structural simulation, optimization and application of RTO's combustion chamber. It provides strong support for the structural optimization design of RTOs in the future.
A 60000 m3/h regenerative thermal oxidizer(RTO) was used to treat the VOCs exhaust from industrial sources. It was found that the residence time of exhaust in the RTO was insufficient during the RTO was running. The concentration of VOCs in the purified gas fluctuated greatly. Numerical simulation of flow field of the RTO showed that the structure design of combustion chamber of the RTO was unreasonable. In order to solve this problem, in this work, the structure of the combustion chamber was optimized by numerical simulation. RTO design and improvement parameters were determined and applied. Inclined plates and retaining walls were installed in the combustion chamber of the RTO. The narrowed channels of the combustion chamber were extended. The results of the simulation and practical application showed that the structure optimization could effectively improve the uniformity of the flow field distribution at the inlet side of the combustion chamber. The overall turbulence kinetic energy in the combustion chamber was increased. The high temperature area in the combustion chamber was expanded. The fluctuation of the VOCs concentration of the purified gas was greatly reduced in practical optimized operation. The concentration differences between different operation stages were reduced by 78%, as low as about 4 mg/m3. In addition, the removal efficiency(RE) of VOCs remained above 99.5%. The highly efficient purification of industrial VOCs exhaust was realized through the structural simulation, optimization and application of RTO's combustion chamber. It provides strong support for the structural optimization design of RTOs in the future.
2022, 40(2): 154-161.
doi: 10.13205/j.hjgc.202202024
Abstract:
The annual output of steel slag in China exceeds 100 million tons, with huge accumulated storage and low utilization rate, which has caused serious harm to the ecological environment. Based on this, this paper carried out the application research of steel slag powder in high performance concrete. The results showed that when the content of steel slag powder exceeded 30% of the total amount of binder, the compressive strength of concrete presented a significant reduction trend. The greater the content of steel slag powder in the total amount of glue material, the more significant its impact; with the increase of steel slag powder and glue material, the impermeability of concrete was significantly improved. When the amount of steel slag powder accounted for 40%~50% of the total amount of glue material, the frost resistance of concrete was relatively better. With the increase of steel slag powder content, the hydration heat of steel slag powder concrete decreased significantly. The temperature rise experiment of mass concrete specimen showed that the steel slag powder concrete specimen could significantly reduce the temperature rise in the center of the concrete specimen, and effectively inhibit the temperature rise cracking of mass concrete specimen, compared with the slag powder and fly ash mixed concrete specimen. The results provided a theoretical basis for the application of steel slag powder in concrete.
The annual output of steel slag in China exceeds 100 million tons, with huge accumulated storage and low utilization rate, which has caused serious harm to the ecological environment. Based on this, this paper carried out the application research of steel slag powder in high performance concrete. The results showed that when the content of steel slag powder exceeded 30% of the total amount of binder, the compressive strength of concrete presented a significant reduction trend. The greater the content of steel slag powder in the total amount of glue material, the more significant its impact; with the increase of steel slag powder and glue material, the impermeability of concrete was significantly improved. When the amount of steel slag powder accounted for 40%~50% of the total amount of glue material, the frost resistance of concrete was relatively better. With the increase of steel slag powder content, the hydration heat of steel slag powder concrete decreased significantly. The temperature rise experiment of mass concrete specimen showed that the steel slag powder concrete specimen could significantly reduce the temperature rise in the center of the concrete specimen, and effectively inhibit the temperature rise cracking of mass concrete specimen, compared with the slag powder and fly ash mixed concrete specimen. The results provided a theoretical basis for the application of steel slag powder in concrete.
2022, 40(2): 162-167,176.
doi: 10.13205/j.hjgc.202202025
Abstract:
In this paper, taking Cr(Ⅵ) contaminated groundwater site as an example, based on the size and reaction medium of PRB wall determined by indoor simulation experiment, the water level and water environment indexes of the monitoring well inside and outside the wall were monitored for four times in 10 months after the completion of the PRB wall. The results showed that the groundwater velocity in the PRB wall was greater than that in the surrounding aquifer. Although the groundwater flow direction changed locally, it still passed through the PRB wall vertically and no flow around was found. The monitoring data of four consecutive periods showed that no Cr(Ⅵ) was detected inside the wall, affected by the wet season, and the concentration of Cr(Ⅵ) in the upper and lower reaches of the wall in the fourth period was significantly higher than that in other periods. The pH value of groundwater in the upstream and downstream of the wall was between 6.5 and 8.5, meeting the requirements of China's national drinking water standard. Due to the corrosion of iron in the wall, the pH value increased rapidly and ranged in 9~10.5, which was significantly higher than that in the upstream and downstream of the wall. There was a strong oxidation-reduction reaction in the wall, and the ORP values monitored in three consecutive periods were negative(-260~-140 mV), indicating a strong reducing environment. Fe(Ⅱ) concentration in the wall was higher than that outside the wall, its distribution was uneven, and the concentration in Well G3-2 was the highest, with a value of 3.52 mg/L; the removal of Cr(Ⅵ) in the wall was carried out simultaneously with the removal of Ca2+, Mg2+, HCO3- and SO4-, and Mg2+ and SO4- were the main influencing factors of Cr(Ⅵ) removal. To sum up, in the case of remediation of Cr(Ⅵ) contaminated groundwater by permeable reaction wall at pilot scale, the wall was in a strong reducing and alkaline environment during the monitoring period of 10 months, the reactive material was highly active, and the remediation effect of hexavalent chromium was obvious.
In this paper, taking Cr(Ⅵ) contaminated groundwater site as an example, based on the size and reaction medium of PRB wall determined by indoor simulation experiment, the water level and water environment indexes of the monitoring well inside and outside the wall were monitored for four times in 10 months after the completion of the PRB wall. The results showed that the groundwater velocity in the PRB wall was greater than that in the surrounding aquifer. Although the groundwater flow direction changed locally, it still passed through the PRB wall vertically and no flow around was found. The monitoring data of four consecutive periods showed that no Cr(Ⅵ) was detected inside the wall, affected by the wet season, and the concentration of Cr(Ⅵ) in the upper and lower reaches of the wall in the fourth period was significantly higher than that in other periods. The pH value of groundwater in the upstream and downstream of the wall was between 6.5 and 8.5, meeting the requirements of China's national drinking water standard. Due to the corrosion of iron in the wall, the pH value increased rapidly and ranged in 9~10.5, which was significantly higher than that in the upstream and downstream of the wall. There was a strong oxidation-reduction reaction in the wall, and the ORP values monitored in three consecutive periods were negative(-260~-140 mV), indicating a strong reducing environment. Fe(Ⅱ) concentration in the wall was higher than that outside the wall, its distribution was uneven, and the concentration in Well G3-2 was the highest, with a value of 3.52 mg/L; the removal of Cr(Ⅵ) in the wall was carried out simultaneously with the removal of Ca2+, Mg2+, HCO3- and SO4-, and Mg2+ and SO4- were the main influencing factors of Cr(Ⅵ) removal. To sum up, in the case of remediation of Cr(Ⅵ) contaminated groundwater by permeable reaction wall at pilot scale, the wall was in a strong reducing and alkaline environment during the monitoring period of 10 months, the reactive material was highly active, and the remediation effect of hexavalent chromium was obvious.
2022, 40(2): 168-176.
doi: 10.13205/j.hjgc.202202026
Abstract:
An environment-friendly road dust suppressant was prepared by using corn straw as the main raw material, enzymatic hydrolysis of straw with cellulase and environmental-friendly additives. The moisture absorption, moisture retention and surface tension of the dust suppressor were tested and characterized. The response surface methodology was also used to optimize the formula of dust suppression agent and prepare the samples of dust suppression agent. The optimal mass ratio of xylanase, acid cellulase, cellulobiase and β-glucanase was 2∶2∶1∶1, in which the water absorption rate of dust suppression agent was used as the evaluation index. The optimal mass ratio of straw∶glycerol∶magnesium chloride∶α-enyl sulfonate∶polyacrylamide was 1∶4∶3∶0.05∶0.001 based on the physical and chemical properties and practical performance of dust depressant. The developed dust suppressant had good wettability and anti-evaporation performance while the dust suppression rate could reach 100% within 2 hours at the wind speed of 7.8 m/s.
An environment-friendly road dust suppressant was prepared by using corn straw as the main raw material, enzymatic hydrolysis of straw with cellulase and environmental-friendly additives. The moisture absorption, moisture retention and surface tension of the dust suppressor were tested and characterized. The response surface methodology was also used to optimize the formula of dust suppression agent and prepare the samples of dust suppression agent. The optimal mass ratio of xylanase, acid cellulase, cellulobiase and β-glucanase was 2∶2∶1∶1, in which the water absorption rate of dust suppression agent was used as the evaluation index. The optimal mass ratio of straw∶glycerol∶magnesium chloride∶α-enyl sulfonate∶polyacrylamide was 1∶4∶3∶0.05∶0.001 based on the physical and chemical properties and practical performance of dust depressant. The developed dust suppressant had good wettability and anti-evaporation performance while the dust suppression rate could reach 100% within 2 hours at the wind speed of 7.8 m/s.
2022, 40(2): 177-183.
doi: 10.13205/j.hjgc.202202027
Abstract:
Effluent trading is a cost-effective and efficient water quality management measure. Due to the physicochemical characteristics of water pollutants and stream self-purification, equity of the measure is facing huge challenges. These will seriously affect the efficiency of effluent trading and the realization of water quality objectives. Trading ratio is an effective way to solve this challenge. In this study, the SWAT model was used to simulate the hydrology and water quality of Dagu River basin. Then the response of NH3-N(ammonia nitrogen) loading in estuary to different pollution sources was obtained. On this basis, the spatial heterogeneity of trading ratio was analyzed, and the uncertainty estimation of the trading ratio system of discharge permits for NH3-N among different pollution sources was carried out. The results can not only lay a foundation for the establishment and improvement of the effluent trading system, but also provide support for watershed management and ecological restoration.
Effluent trading is a cost-effective and efficient water quality management measure. Due to the physicochemical characteristics of water pollutants and stream self-purification, equity of the measure is facing huge challenges. These will seriously affect the efficiency of effluent trading and the realization of water quality objectives. Trading ratio is an effective way to solve this challenge. In this study, the SWAT model was used to simulate the hydrology and water quality of Dagu River basin. Then the response of NH3-N(ammonia nitrogen) loading in estuary to different pollution sources was obtained. On this basis, the spatial heterogeneity of trading ratio was analyzed, and the uncertainty estimation of the trading ratio system of discharge permits for NH3-N among different pollution sources was carried out. The results can not only lay a foundation for the establishment and improvement of the effluent trading system, but also provide support for watershed management and ecological restoration.
2022, 40(2): 184-190.
doi: 10.13205/j.hjgc.202202028
Abstract:
There are many types of waste plastic recycling technologies in South China, and a method system for comprehensive performance of multiple recycling technologies has not been formed. This study intends to take waste polypropylene(PP) in South China as an example to construct an environmental-economic comprehensive performance evaluation method for waste plastic recycling technology. The comprehensive performance results show that the modified regeneration technology has the highest comprehensive performance. The comparison results of various recycling technologies in South China indicate that the use of degraded technologies should be upgraded to reduce the market share of chemical cracking and incineration power generation technologies to achieve the highest comprehensive performance in South China. Based on this, relevant industries should expand the promotion of modified recycling technology and increase the usage rate of the waste plastic recycling market. In addition, the government should adopt relevant promotion policies and increase financial investment in recycling process facilities to upgrade degraded utilization to modified regeneration. It will not only improve the economic performance of technology application enterprises, but also reduce the cost of environmental pollution in South China.
There are many types of waste plastic recycling technologies in South China, and a method system for comprehensive performance of multiple recycling technologies has not been formed. This study intends to take waste polypropylene(PP) in South China as an example to construct an environmental-economic comprehensive performance evaluation method for waste plastic recycling technology. The comprehensive performance results show that the modified regeneration technology has the highest comprehensive performance. The comparison results of various recycling technologies in South China indicate that the use of degraded technologies should be upgraded to reduce the market share of chemical cracking and incineration power generation technologies to achieve the highest comprehensive performance in South China. Based on this, relevant industries should expand the promotion of modified recycling technology and increase the usage rate of the waste plastic recycling market. In addition, the government should adopt relevant promotion policies and increase financial investment in recycling process facilities to upgrade degraded utilization to modified regeneration. It will not only improve the economic performance of technology application enterprises, but also reduce the cost of environmental pollution in South China.
2022, 40(2): 191-198.
doi: 10.13205/j.hjgc.202202029
Abstract:
A large amount of residual mud from subway engineering will have serious environmental impacts in the process of disposal. Accurately quantifying the environmental impacts of residual mud from subway engineering is the premise of effective management. In this study, firstly, the estimation method of the amount of land occupied by the residual mud landfill of the subway project was established. Secondly, based on field investigation, semi-structured interview and literature review, the life cycle carbon emission assessment method of residual mud from subway engineering was constructed. Finally, taking Shenzhen Metro Line 14 as an example, the amount of land occupied by landfill and its carbon emission in the whole life cycle were quantified. The results showed that: the land occupation area for landfill disposal of residual mud from Shenzhen Metro Line 14 was about 1.634 million m2, which would generate a landfill cost of 40.85 million yuan; the total life cycle CO2 emission of residual mud from Shenzhen metro line 14 was about 1.8 E+07 kgCO2eq. The research results can provide a theoretical model and data reference for the government to scientifically formulate the management policy of the residual mud from subway engineering.
A large amount of residual mud from subway engineering will have serious environmental impacts in the process of disposal. Accurately quantifying the environmental impacts of residual mud from subway engineering is the premise of effective management. In this study, firstly, the estimation method of the amount of land occupied by the residual mud landfill of the subway project was established. Secondly, based on field investigation, semi-structured interview and literature review, the life cycle carbon emission assessment method of residual mud from subway engineering was constructed. Finally, taking Shenzhen Metro Line 14 as an example, the amount of land occupied by landfill and its carbon emission in the whole life cycle were quantified. The results showed that: the land occupation area for landfill disposal of residual mud from Shenzhen Metro Line 14 was about 1.634 million m2, which would generate a landfill cost of 40.85 million yuan; the total life cycle CO2 emission of residual mud from Shenzhen metro line 14 was about 1.8 E+07 kgCO2eq. The research results can provide a theoretical model and data reference for the government to scientifically formulate the management policy of the residual mud from subway engineering.
2022, 40(2): 199-205.
doi: 10.13205/j.hjgc.202202030
Abstract:
The large amount of packaging waste brought by catering take-out industry is threatening the safety of ecological environment in campus, and how to recycle it has become an urgent problem. In this paper, based on the framework of UTAUT theory, we constructed the influence path between four core variables, performance expectancy, effort expectancy, social influence, perceived value, and three control variables, gender, educational, frequency. Then, the structural equation model was used to empirically calculate the model path and analyze the influencing factors of college students' intention to participate in the packaging classification. The result showed that performance expectancy, effort expectancy and perceived value had significant positive influence on college students' participation intention, while social influence had no significant influence on college students' participation intention. Moreover, performance expectancy had significant positive influence on college students' participation intention indirectly through the partial mediating effect of effort expectancy and perceived value. The gender, educational background and frequency had a certain moderating effect on the relationship between variables. Finally, scientific suggestions were given on the policy, which are conducive to increase the necycling rate of take-out packaging and construct the Green Campus.
The large amount of packaging waste brought by catering take-out industry is threatening the safety of ecological environment in campus, and how to recycle it has become an urgent problem. In this paper, based on the framework of UTAUT theory, we constructed the influence path between four core variables, performance expectancy, effort expectancy, social influence, perceived value, and three control variables, gender, educational, frequency. Then, the structural equation model was used to empirically calculate the model path and analyze the influencing factors of college students' intention to participate in the packaging classification. The result showed that performance expectancy, effort expectancy and perceived value had significant positive influence on college students' participation intention, while social influence had no significant influence on college students' participation intention. Moreover, performance expectancy had significant positive influence on college students' participation intention indirectly through the partial mediating effect of effort expectancy and perceived value. The gender, educational background and frequency had a certain moderating effect on the relationship between variables. Finally, scientific suggestions were given on the policy, which are conducive to increase the necycling rate of take-out packaging and construct the Green Campus.
2022, 40(2): 206-213,224.
doi: 10.13205/j.hjgc.202202031
Abstract:
Permeable reactive barrier(PRB) is currently one of the most economical and effective in-situ groundwater treatment technologies, however, the passivation and clogging of pore space due to mineral precipitation, gas generation and biological activity results into performance failure of barrier materials, which affects the lifetime and efficiency of PRB. In order to alleviate or resolve the limitation of passivation and clogging on application of PRB, the progresses and some cases on passivation and clogging of permeable reactive barrier(PRB) were researched and reviewed, and the various types, causes and mechanisms of PRB passivation and clogging were analyzed, including the passivation and clogging types resulted from mineral precipitation, gas generation, influence of pH and biological activities, etc. Especially, primary mineral precipitation types including, calcium-based mineral precipitation, Fe and Al mineral precipitation, and precipitation due to phosphate, silicate and silicon oxide were discussed. In order to improve operation efficiency and lifetime of PRB, the different types, influences factors and running conditions of passivation and clogging were analyzed, which could provide technical support to design PRB structure successfully, improve operation efficiency and service life of PRB, and develop PRB to be a long-term effective remediation technology.
Permeable reactive barrier(PRB) is currently one of the most economical and effective in-situ groundwater treatment technologies, however, the passivation and clogging of pore space due to mineral precipitation, gas generation and biological activity results into performance failure of barrier materials, which affects the lifetime and efficiency of PRB. In order to alleviate or resolve the limitation of passivation and clogging on application of PRB, the progresses and some cases on passivation and clogging of permeable reactive barrier(PRB) were researched and reviewed, and the various types, causes and mechanisms of PRB passivation and clogging were analyzed, including the passivation and clogging types resulted from mineral precipitation, gas generation, influence of pH and biological activities, etc. Especially, primary mineral precipitation types including, calcium-based mineral precipitation, Fe and Al mineral precipitation, and precipitation due to phosphate, silicate and silicon oxide were discussed. In order to improve operation efficiency and lifetime of PRB, the different types, influences factors and running conditions of passivation and clogging were analyzed, which could provide technical support to design PRB structure successfully, improve operation efficiency and service life of PRB, and develop PRB to be a long-term effective remediation technology.
2022, 40(2): 214-224.
doi: 10.13205/j.hjgc.202202032
Abstract:
This paper summarized the relevant progress of fixed biofilm-activated sludge(IFAS) process, mainly including pollutant removal performance of single process and coupling with other processes, influence of operating parameters on the process,and the simulation and optimization of the process by dynamic modeling. Compared with the traditional activated sludge(CAS) process, the IFAS process combined the advantages of suspended sludge and attached biofilm, and showed higher removal performance on organic matter, nitrogen and other pollutants. The coupling of IFAS process and other new wastewater treatment processes improved the metabolic activity, diversity and selectivity of functional bacteria. In terms of operation shock resistance, the IFAS process not only exhibited high stability as C/N changes, but also had a high degree of adaptability under low temperature and high ammonia nitrogen concentration. In the optimization of the process, kinetic modeling allowed optimizing the operation parameters through simulating the interaction between sludge and biofilm. The IFAS process advantages in the performances of high pollutant removal and stability would be an alternative technology approach to the operation upgrading of wastewater treatment plants(WWTPs) in China. The performance improvement of IFAS process should be focused on the subsequent studies such as development of high-performance carriers, balance of biofilm formation and detachment, interaction between suspended sludge and biofilm, as well as the microbial characteristics.
This paper summarized the relevant progress of fixed biofilm-activated sludge(IFAS) process, mainly including pollutant removal performance of single process and coupling with other processes, influence of operating parameters on the process,and the simulation and optimization of the process by dynamic modeling. Compared with the traditional activated sludge(CAS) process, the IFAS process combined the advantages of suspended sludge and attached biofilm, and showed higher removal performance on organic matter, nitrogen and other pollutants. The coupling of IFAS process and other new wastewater treatment processes improved the metabolic activity, diversity and selectivity of functional bacteria. In terms of operation shock resistance, the IFAS process not only exhibited high stability as C/N changes, but also had a high degree of adaptability under low temperature and high ammonia nitrogen concentration. In the optimization of the process, kinetic modeling allowed optimizing the operation parameters through simulating the interaction between sludge and biofilm. The IFAS process advantages in the performances of high pollutant removal and stability would be an alternative technology approach to the operation upgrading of wastewater treatment plants(WWTPs) in China. The performance improvement of IFAS process should be focused on the subsequent studies such as development of high-performance carriers, balance of biofilm formation and detachment, interaction between suspended sludge and biofilm, as well as the microbial characteristics.
2022, 40(2): 225-234.
doi: 10.13205/j.hjgc.202202033
Abstract:
Nanomaterials is a new material that uses nanotechnology to transform the structure of nanomaterials. With great specific surface area, rich surface functional groups, and low cost, nanomaterials and modified nanocomposites have been widely applied in environmental remediation. However, due to its shortcomings such as easy agglomeration and poor stability, its application in environmental pollution remediation is limited. At present, many researches have added stabilizers to improve the performance of nanomaterials and their composite materials. However, no systematic review was reported on the application of stabilizers in the improvement of nanomaterials. Therefore, this article reviewed the types, characterization of stabilizers, and the synergy between stabilizers and nanomaterials. At last, key points and research directions on stabilized-nanomaterial were proposed.
Nanomaterials is a new material that uses nanotechnology to transform the structure of nanomaterials. With great specific surface area, rich surface functional groups, and low cost, nanomaterials and modified nanocomposites have been widely applied in environmental remediation. However, due to its shortcomings such as easy agglomeration and poor stability, its application in environmental pollution remediation is limited. At present, many researches have added stabilizers to improve the performance of nanomaterials and their composite materials. However, no systematic review was reported on the application of stabilizers in the improvement of nanomaterials. Therefore, this article reviewed the types, characterization of stabilizers, and the synergy between stabilizers and nanomaterials. At last, key points and research directions on stabilized-nanomaterial were proposed.
2022, 40(2): 235-239.
doi: 10.13205/j.hjgc.202202034
Abstract:
The soundness problem caused by the expansion of converter slag is the main reason restricting the large-scale application of converter slag in road construction and building materials. This paper analyzed main reasons of the poor soundness of converter slag in China, and compared the advantages and disadvantages of each evaluation method from five aspects: f-CaO content determination could be used as an auxiliary mean to evaluate the content of main expansive minerals in steel slag quickly; the autoclaved pulverization rate was suitable to evaluate the expansion caused by f-CaO and periclase; the linear expansion rate method of mortar bar needed to be further improved; the soundness of steel slag used in road construction could be effectively tested by 10 days dimmersion expansion rate in of compacted specimens; autoclave method is too severe to test the soundness of the concrete with steel slag aggregate. Combing these five evaluation methods can provide reference for the soundness quality control and research of steel slag as aggregate.
The soundness problem caused by the expansion of converter slag is the main reason restricting the large-scale application of converter slag in road construction and building materials. This paper analyzed main reasons of the poor soundness of converter slag in China, and compared the advantages and disadvantages of each evaluation method from five aspects: f-CaO content determination could be used as an auxiliary mean to evaluate the content of main expansive minerals in steel slag quickly; the autoclaved pulverization rate was suitable to evaluate the expansion caused by f-CaO and periclase; the linear expansion rate method of mortar bar needed to be further improved; the soundness of steel slag used in road construction could be effectively tested by 10 days dimmersion expansion rate in of compacted specimens; autoclave method is too severe to test the soundness of the concrete with steel slag aggregate. Combing these five evaluation methods can provide reference for the soundness quality control and research of steel slag as aggregate.
