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2020 Vol. 38, No. 5
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2020, 38(5): 1-7,29.
doi: 10.13205/j.hjgc.202005001
Abstract:
In order to solve the problem of long start-up period of the aerobic granular sludge system, the paper reviewed the forming mechanism, the main affecting factors and the methods to promote aerobic granulation. It was found that inducing microbes to secrete more extracellular polymer (EPS) could promote the rapid formation of initial microbial aggregates, and thus decreased the aerobic granulation time by adjusting the parameters of hydraulic shear force, settling time, organic load and starvation stage of the reactors. Therefore, the current measures of rapid granulation was essentially based on the method of inducing the rapidly forming initial microbe aggregates or directly adding aggregates, to realize the shortening of the time for aerobic granulation. Finally, this paper pointed out the problems existing in the rapid cultivation of aerobic granule, and the key to solve the related problems, and the future research focus is to clarify the formation mechanism of aerobic granule sludge, establish the standard of aerobic granulation and the cultivation indexes system.
In order to solve the problem of long start-up period of the aerobic granular sludge system, the paper reviewed the forming mechanism, the main affecting factors and the methods to promote aerobic granulation. It was found that inducing microbes to secrete more extracellular polymer (EPS) could promote the rapid formation of initial microbial aggregates, and thus decreased the aerobic granulation time by adjusting the parameters of hydraulic shear force, settling time, organic load and starvation stage of the reactors. Therefore, the current measures of rapid granulation was essentially based on the method of inducing the rapidly forming initial microbe aggregates or directly adding aggregates, to realize the shortening of the time for aerobic granulation. Finally, this paper pointed out the problems existing in the rapid cultivation of aerobic granule, and the key to solve the related problems, and the future research focus is to clarify the formation mechanism of aerobic granule sludge, establish the standard of aerobic granulation and the cultivation indexes system.
2020, 38(5): 8-12,35.
doi: 10.13205/j.hjgc.202005002
Abstract:
Based on seasonal sampling and analysis on the sediment microorganisms in Lake Balihe from July 2017 to April 2018, the dominant generas of bacteria and archaea were identified by the dominance index. These dominant generas of bacteria and archaea were classified, respectively, and their development space were also analyzed by niche breadth, niche overlap index and ecological response rate. The results showed that 5 phyla, 13 dominant generas of bacteria mainly concentrated in ProteoBacteria and Firmicutes, while 4 phyla, 8 dominant generas of archaea mailly concentrated in Euryarchaeota. According to the survival and environmental adaptability, these dominant generas of bacteria and archaea were classified into 4 and 3 categories, namely. Besides, the majority of the dominant bacteria had development space in the seasons except spring, while most of the dominant archaea developed and inhibited alternately in four seasons.
Based on seasonal sampling and analysis on the sediment microorganisms in Lake Balihe from July 2017 to April 2018, the dominant generas of bacteria and archaea were identified by the dominance index. These dominant generas of bacteria and archaea were classified, respectively, and their development space were also analyzed by niche breadth, niche overlap index and ecological response rate. The results showed that 5 phyla, 13 dominant generas of bacteria mainly concentrated in ProteoBacteria and Firmicutes, while 4 phyla, 8 dominant generas of archaea mailly concentrated in Euryarchaeota. According to the survival and environmental adaptability, these dominant generas of bacteria and archaea were classified into 4 and 3 categories, namely. Besides, the majority of the dominant bacteria had development space in the seasons except spring, while most of the dominant archaea developed and inhibited alternately in four seasons.
2020, 38(5): 13-17,42.
doi: 10.13205/j.hjgc.202005003
Abstract:
On the basis of a single factor study, capillary water absorption time (CST), sedimentation curve, scanning electron microscope (SEM), and three-dimensional fluorescence spectra of EPS in printing and dyeing sludge was explored, and the effect of microwave, lysozyme, microwave and lysozyme joint treatment on the dewatering of printing and dyeing sludge was compared. The sludge dewatering performance was characterized by orthogonal test, and the optimal conditions for the joint treatment were: the enzymolysis temperature was 40 ℃, the amount of lysozyme added was 0.09 g/g(TSS), the enzymolysis time was 3 h, the microwave power was 400 W, and the microwave time was 150 s. The single factor experiment results showed that: microwave (400 W, 180 s) and lysozyme (0.09 g/g(TSS), 40 ℃, 4 h) treatment could promote sludge cracking and dissolution of extracellular polymers; under those two conditions, the growth rate of dissolved polysaccharide and total proteins was 609% and 306% respectively; CST was decreased by 12.2% and 22.0%, respectively. At the same time, the joint treatment of microwave and lysozymes increased the dissolve polysaccharides and total proteins by 1353%, and decreased CST by 49.3%,and sludge sedimentation performance was the best then. SEM results showed: the combination of microwave and lysozyme made the structure of the sludge changed obviously. The sludge bacteria micelle was broken, the floc structure became loose, and the intracellular bound water was successfully converted into free water, which was beneficial to the sludge dehydration.
On the basis of a single factor study, capillary water absorption time (CST), sedimentation curve, scanning electron microscope (SEM), and three-dimensional fluorescence spectra of EPS in printing and dyeing sludge was explored, and the effect of microwave, lysozyme, microwave and lysozyme joint treatment on the dewatering of printing and dyeing sludge was compared. The sludge dewatering performance was characterized by orthogonal test, and the optimal conditions for the joint treatment were: the enzymolysis temperature was 40 ℃, the amount of lysozyme added was 0.09 g/g(TSS), the enzymolysis time was 3 h, the microwave power was 400 W, and the microwave time was 150 s. The single factor experiment results showed that: microwave (400 W, 180 s) and lysozyme (0.09 g/g(TSS), 40 ℃, 4 h) treatment could promote sludge cracking and dissolution of extracellular polymers; under those two conditions, the growth rate of dissolved polysaccharide and total proteins was 609% and 306% respectively; CST was decreased by 12.2% and 22.0%, respectively. At the same time, the joint treatment of microwave and lysozymes increased the dissolve polysaccharides and total proteins by 1353%, and decreased CST by 49.3%,and sludge sedimentation performance was the best then. SEM results showed: the combination of microwave and lysozyme made the structure of the sludge changed obviously. The sludge bacteria micelle was broken, the floc structure became loose, and the intracellular bound water was successfully converted into free water, which was beneficial to the sludge dehydration.
2020, 38(5): 18-22.
doi: 10.13205/j.hjgc.202005004
Abstract:
Foams and blocks were produced in the circulating water system of a coal-to-methanol plant due to slight leakage. The fouling was identified to be mainly bacterial cellulose after optical microscopic observation, scanning electron microscopy and chemical coloration analysis, from where a dominant strain was obstained by microbiological isolation. The strain was identified as a strain of Gluconacetobacter xylinus, according to 16S rDNA sequence and BIOLOG identification. Cellulose production of the strain were studied under different conditions. The results showed that pH and methanol concentration had a great influence on the cellulose production of the strain. Maximum cellulose production appeared when methanol concentration 15~25 mL/L, and the cellulose production with pH of 8 and 9 was only 50% of that with pH of 5.0. When co-growth with methanol-degrading bacteria, cellulose-producing ability of the strain decreased by 37.9%, owning to competitive exclusion and niche competition. This discovery provided a scientific basis for the biological control of cellulose fouling in the coal-to-methanol circulating water system.
Foams and blocks were produced in the circulating water system of a coal-to-methanol plant due to slight leakage. The fouling was identified to be mainly bacterial cellulose after optical microscopic observation, scanning electron microscopy and chemical coloration analysis, from where a dominant strain was obstained by microbiological isolation. The strain was identified as a strain of Gluconacetobacter xylinus, according to 16S rDNA sequence and BIOLOG identification. Cellulose production of the strain were studied under different conditions. The results showed that pH and methanol concentration had a great influence on the cellulose production of the strain. Maximum cellulose production appeared when methanol concentration 15~25 mL/L, and the cellulose production with pH of 8 and 9 was only 50% of that with pH of 5.0. When co-growth with methanol-degrading bacteria, cellulose-producing ability of the strain decreased by 37.9%, owning to competitive exclusion and niche competition. This discovery provided a scientific basis for the biological control of cellulose fouling in the coal-to-methanol circulating water system.
2020, 38(5): 23-29.
doi: 10.13205/j.hjgc.202005005
Abstract:
Phthalic acid esters (PAEs) are a class of endocrine disruptors commonly found in various water environments. Being long-term residents in aquatic environment, PAEs have toxic effects on aquatic organisms, and are also harmful to the human health through multiple exposure pathways. In this paper, the pollution status of PAEs in surface water, sediments, groundwater, sewage treatment plants and drinking water in different countries and regions, as well as the toxic effects and environmental risks in water environment at China and abroad were reviewed. The limitations of different water quality standards on PAEs were also summarized. In addition, the trend for further research on the environmental risk of PAEs in water environment was prospected.
Phthalic acid esters (PAEs) are a class of endocrine disruptors commonly found in various water environments. Being long-term residents in aquatic environment, PAEs have toxic effects on aquatic organisms, and are also harmful to the human health through multiple exposure pathways. In this paper, the pollution status of PAEs in surface water, sediments, groundwater, sewage treatment plants and drinking water in different countries and regions, as well as the toxic effects and environmental risks in water environment at China and abroad were reviewed. The limitations of different water quality standards on PAEs were also summarized. In addition, the trend for further research on the environmental risk of PAEs in water environment was prospected.
2020, 38(5): 30-35.
doi: 10.13205/j.hjgc.202005006
Abstract:
Electrochemical oxidation is an efficient and environmental-friendly technology with significant advantages in the treatment of antibiotics including amoxicillin. The traditional two-dimensional electrode reactor packed activated carbon as particle electrode will reduce the mass transfer resistance in the system and improve current efficiency. This study explored the optimal conditions for the treatment of amoxicillin simulated wastewater by a three-dimensional electrode reactor, and compared with a two-dimensional electrode reactor and the adsorption process. The optimal conditions were as follows: the quartz sand accounted for 10% of the total volume of the packed particles, the current density was 5 mA/cm2, the electrolyte was 17 mmol/L Na2SO4, and the initial pH of the solution was 5.56. Under the optimal condition, the TOC removal rate was 49.1%, and the amoxicillin removal rate was 99.0%. The synergy between electrolysis and adsorption in the three-dimensional electrodes reactor made the TOC removal rate higher than that of adsorption and traditional two-dimensional electrode reactor (49.1%>22.0%+8.7%), showing a good application prospect.
Electrochemical oxidation is an efficient and environmental-friendly technology with significant advantages in the treatment of antibiotics including amoxicillin. The traditional two-dimensional electrode reactor packed activated carbon as particle electrode will reduce the mass transfer resistance in the system and improve current efficiency. This study explored the optimal conditions for the treatment of amoxicillin simulated wastewater by a three-dimensional electrode reactor, and compared with a two-dimensional electrode reactor and the adsorption process. The optimal conditions were as follows: the quartz sand accounted for 10% of the total volume of the packed particles, the current density was 5 mA/cm2, the electrolyte was 17 mmol/L Na2SO4, and the initial pH of the solution was 5.56. Under the optimal condition, the TOC removal rate was 49.1%, and the amoxicillin removal rate was 99.0%. The synergy between electrolysis and adsorption in the three-dimensional electrodes reactor made the TOC removal rate higher than that of adsorption and traditional two-dimensional electrode reactor (49.1%>22.0%+8.7%), showing a good application prospect.
2020, 38(5): 36-42.
doi: 10.13205/j.hjgc.202005007
Abstract:
With the development of modern analysis technologies and the enhanced consciousness of people for environmental security, occurrence of antibiotics as emerging organic contaminants (EOCs) in the environment have received growing global concerns. The present paper reviewed the pollution status of antibiotics in varied waters and analyzed the source and environmental risks of antibiotics in the aquatic environment. Results reveal that both detection frequencies and concentrations of antibiotics in coastal waters or rivers are higher than those in lakes and underground waters, which was probably due to the more frequent human activities and wastewater discharge from wastewater treatment plants (WWTPs) in the former. Wastewater discharge from WWTPs is considered one of the main resources of antibiotics present in the aquatic environment. And the antibiotics removal efficiencies in WWTPs are related to physicochemical property of antibiotics and treatment processes used in WWTPs.
With the development of modern analysis technologies and the enhanced consciousness of people for environmental security, occurrence of antibiotics as emerging organic contaminants (EOCs) in the environment have received growing global concerns. The present paper reviewed the pollution status of antibiotics in varied waters and analyzed the source and environmental risks of antibiotics in the aquatic environment. Results reveal that both detection frequencies and concentrations of antibiotics in coastal waters or rivers are higher than those in lakes and underground waters, which was probably due to the more frequent human activities and wastewater discharge from wastewater treatment plants (WWTPs) in the former. Wastewater discharge from WWTPs is considered one of the main resources of antibiotics present in the aquatic environment. And the antibiotics removal efficiencies in WWTPs are related to physicochemical property of antibiotics and treatment processes used in WWTPs.
2020, 38(5): 43-48.
doi: 10.13205/j.hjgc.202005008
Abstract:
A heterotrophic nitrification and aerobic denitrification bacterium strain named XK51 was isolated and purified from nitrogen-contaminated shallow aquifer porous media. The strain was identified as Pseudomonas Putida by morphological observation, physiological and biochemical characteristics and 16S rDNA gene sequence analysis. The results showed that strain XK51 was a facultative denitrifying bacteria, which could achieve high denitrification efficiencies under aerobic or anaerobic conditions. The maximum and average denitrification rate were 27.3 mg/(L·h) and 4.4 mg/(L·h), the nitrate removal efficiency was 95.3%. XK51 also had high heterotrophic nitrification capacity, and its maximum and average nitrification rate were 4.2 mg/(L·h) and 1.4 mg/(L·h), then the ammonia removal efficiency was 98.5%. The optimum carbon source was trisodium citrate, and the optimum growth temperature ranged from 28 to 35 ℃, with a preferred value of 30 ℃. The optimum cultivating pH value ranged from 6.5 to 8.0, with a preferred value of 7.0. Strain XK51 could simultaneously carry out heterotrophic nitrification and simultaneous nitrification-denitrification with no obvious nitrite and nitrate accumulation during cultivation. It has potential engineering application value in nitrogen-containing wastewater treatment and nitrogen pollution remediation of groundwater.
A heterotrophic nitrification and aerobic denitrification bacterium strain named XK51 was isolated and purified from nitrogen-contaminated shallow aquifer porous media. The strain was identified as Pseudomonas Putida by morphological observation, physiological and biochemical characteristics and 16S rDNA gene sequence analysis. The results showed that strain XK51 was a facultative denitrifying bacteria, which could achieve high denitrification efficiencies under aerobic or anaerobic conditions. The maximum and average denitrification rate were 27.3 mg/(L·h) and 4.4 mg/(L·h), the nitrate removal efficiency was 95.3%. XK51 also had high heterotrophic nitrification capacity, and its maximum and average nitrification rate were 4.2 mg/(L·h) and 1.4 mg/(L·h), then the ammonia removal efficiency was 98.5%. The optimum carbon source was trisodium citrate, and the optimum growth temperature ranged from 28 to 35 ℃, with a preferred value of 30 ℃. The optimum cultivating pH value ranged from 6.5 to 8.0, with a preferred value of 7.0. Strain XK51 could simultaneously carry out heterotrophic nitrification and simultaneous nitrification-denitrification with no obvious nitrite and nitrate accumulation during cultivation. It has potential engineering application value in nitrogen-containing wastewater treatment and nitrogen pollution remediation of groundwater.
2020, 38(5): 49-53,209.
doi: 10.13205/j.hjgc.202005009
Abstract:
In traditional aerated ecological floating wetland, the water body was usually stirred vigorously, and the microbial membrane and the rhizosphere were not stabilized, thus, the nitrogen and phosphorus removal effects of the polluted water were affected. Therefore, a new micro-nano aeration-eco-float wetland was constructed in this paper. The chamber generated micro-nano bubbles through a micro-nano rubber aeration tube to improve the removal of nitrogen and phosphorus. The results showed that the removal rate of NH4+-N in the aerated group was 99.8% in 20 days; the removal rate of TP was 93.03%; the removal rate of NO3--N was 78%, so that the water with inferior Ⅴ quality could be treated to meet Class III emission standards, and the weak acidic water could also be modified into neutral. The experiment proved that the micro-nano aeration-eco-floating island combined technology could effectively improve the dissolved oxygen content of the water body in short term, and reduce stirring to a weak level to the water body, which helped to improve the stability of the bio-filler membrane, and the removal effect of nitrogen and phosphorus was higher than the traditional ecological floating wetland obviously. This experiment provided a technical basis for the promotion and application of micro-nano aeration-ecological floating wetland joint technology.
In traditional aerated ecological floating wetland, the water body was usually stirred vigorously, and the microbial membrane and the rhizosphere were not stabilized, thus, the nitrogen and phosphorus removal effects of the polluted water were affected. Therefore, a new micro-nano aeration-eco-float wetland was constructed in this paper. The chamber generated micro-nano bubbles through a micro-nano rubber aeration tube to improve the removal of nitrogen and phosphorus. The results showed that the removal rate of NH4+-N in the aerated group was 99.8% in 20 days; the removal rate of TP was 93.03%; the removal rate of NO3--N was 78%, so that the water with inferior Ⅴ quality could be treated to meet Class III emission standards, and the weak acidic water could also be modified into neutral. The experiment proved that the micro-nano aeration-eco-floating island combined technology could effectively improve the dissolved oxygen content of the water body in short term, and reduce stirring to a weak level to the water body, which helped to improve the stability of the bio-filler membrane, and the removal effect of nitrogen and phosphorus was higher than the traditional ecological floating wetland obviously. This experiment provided a technical basis for the promotion and application of micro-nano aeration-ecological floating wetland joint technology.
2020, 38(5): 54-59,195.
doi: 10.13205/j.hjgc.202005010
Abstract:
Taking actual domestic sewage with C/N of about 3 as the treatment object, the influence of influent mode and the position of the recirculation point on the function of denitrification and dephosphorization on multi-stage biological contact oxidation porcess was evaluated. The results showed that the removal rate of COD was 87.61% and 78.94% respectively, under the conditions of continuous water inlet and intermittent water inflow. But the average concentration of effluent COD met the Grade A in China’s national standard, GB 18918—2002. And the system had stronger ability for resisting shock load. When the mixed liquid was returned from the sixth grid to the first grid, the removal rate of COD and TN was 88.78% and 83.10% respectively, and it met the Grade A standard of GB 18918—2002 sewage discharge. The treatment effect of TN was related to the position of the recirculation point, and the sludge volume of the system was very low, with no excess sludge discharged. While it had little effect on total phosphorus removal in this condition. The chemical removal of total phosphorus was used. The removal effect of total phosphorus was independent on the position of the recirculation point. Through the analysis of the system biodiversity and biofilm quality, it was found that the system microbial population structure was changed by increasing the reflux. It improved the system nitrogen removal efficiency.
Taking actual domestic sewage with C/N of about 3 as the treatment object, the influence of influent mode and the position of the recirculation point on the function of denitrification and dephosphorization on multi-stage biological contact oxidation porcess was evaluated. The results showed that the removal rate of COD was 87.61% and 78.94% respectively, under the conditions of continuous water inlet and intermittent water inflow. But the average concentration of effluent COD met the Grade A in China’s national standard, GB 18918—2002. And the system had stronger ability for resisting shock load. When the mixed liquid was returned from the sixth grid to the first grid, the removal rate of COD and TN was 88.78% and 83.10% respectively, and it met the Grade A standard of GB 18918—2002 sewage discharge. The treatment effect of TN was related to the position of the recirculation point, and the sludge volume of the system was very low, with no excess sludge discharged. While it had little effect on total phosphorus removal in this condition. The chemical removal of total phosphorus was used. The removal effect of total phosphorus was independent on the position of the recirculation point. Through the analysis of the system biodiversity and biofilm quality, it was found that the system microbial population structure was changed by increasing the reflux. It improved the system nitrogen removal efficiency.
2020, 38(5): 60-64,190.
doi: 10.13205/j.hjgc.202005011
Abstract:
This paper evaluated and analyzed the water quality improvement effect in Haihe River Basin in Henan province during 2015—2018 using single factor evaluation method, comprehensive pollution index evaluation method, and fuzzy comprehensive evaluation method. The results showed that the three evaluation methods were basically consistent, and the overall water quality in Haihe River Basin in Henan province showed a trend of improvement in 2015—2018. But the emphasis of each method was different. The results of single factor evaluation showed that the number of category Ⅰ—Ⅲ pollution factors of 21 pollution factors in Haihe River Basin increased from 69.63% in 2015 to 89.52% in 2018, and the number of category inferior Ⅴ pollution factors decreased from 15.13% in 2015 to 0.85% in 2018. The comprehensive pollution index of Haihe Basin in Henan province decreased from 0.89 in 2015 to 0.56 in 2018, and water quality grades were improved from moderate pollution to light pollution. The water quality grades of the eight rivers in 2015 were lower than moderate pollution, including Wei River, Communist Canal, Dasha River, Anyang River, Tang River, Majia River. The results of fuzzy comprehensive evaluation showed that the weights of ammonia nitrogen and total phosphorus were the largest among the nine evaluation factors, the main pollution factors in Haihe River Basin in Henan province. And the water quality of eight rivers was improved to category Ⅰ—Ⅲ by 2018. Single factor evaluation method, comprehensive pollution index evaluation method were more suitable for management analysis, while fuzzy comprehensive evaluation was prefered in research work.
This paper evaluated and analyzed the water quality improvement effect in Haihe River Basin in Henan province during 2015—2018 using single factor evaluation method, comprehensive pollution index evaluation method, and fuzzy comprehensive evaluation method. The results showed that the three evaluation methods were basically consistent, and the overall water quality in Haihe River Basin in Henan province showed a trend of improvement in 2015—2018. But the emphasis of each method was different. The results of single factor evaluation showed that the number of category Ⅰ—Ⅲ pollution factors of 21 pollution factors in Haihe River Basin increased from 69.63% in 2015 to 89.52% in 2018, and the number of category inferior Ⅴ pollution factors decreased from 15.13% in 2015 to 0.85% in 2018. The comprehensive pollution index of Haihe Basin in Henan province decreased from 0.89 in 2015 to 0.56 in 2018, and water quality grades were improved from moderate pollution to light pollution. The water quality grades of the eight rivers in 2015 were lower than moderate pollution, including Wei River, Communist Canal, Dasha River, Anyang River, Tang River, Majia River. The results of fuzzy comprehensive evaluation showed that the weights of ammonia nitrogen and total phosphorus were the largest among the nine evaluation factors, the main pollution factors in Haihe River Basin in Henan province. And the water quality of eight rivers was improved to category Ⅰ—Ⅲ by 2018. Single factor evaluation method, comprehensive pollution index evaluation method were more suitable for management analysis, while fuzzy comprehensive evaluation was prefered in research work.
2020, 38(5): 65-69.
doi: 10.13205/j.hjgc.202005012
Abstract:
The content characteristics of TN, TP, TK and OM, as well as 6 kinds of heavy metals including Cr, Cu, Ni, Pb, Zn, As in the sludge of 32 urban sewage treatment plants in different areas of Shaanxi province were investigated in different water periods. The results indicated that:1) The contents of N, P nutrients and OM in urban sludge in Shaanxi province were abundant, but TK content was not high. The distribution characteristics of the total nutrient content of sludge generally showed the sequence of low water period>flat water period>abundant water period, in which TN and OM contents were very significantly affected by the water period (PJ-T<0.001), while TP and TK contents were not significantly affected by the water period (PJ-T>0.05). 2) The distribution of heavy metal contents in urban sludge of Shaanxi province showed log-normal. The contents sequence of 6 kinds of heavy metals were Zn>Cu>Cr>Pb>Ni>As. There was no significant difference in heavy metals contents of sludge in different water periods (PANOVA>0.05). 3) The urban sludge in Shaanxi province had a high agricultural value and the heavy metal contents in urban sludge in Shaanxi province were generally at a relatively lower level; the sludge was suitable for application in forest land, pasture grassland and cultivated land without growing edible crops; land modification for medium alkaline soil. Meanwhile, special attention should be paid to As content in the sludge.
The content characteristics of TN, TP, TK and OM, as well as 6 kinds of heavy metals including Cr, Cu, Ni, Pb, Zn, As in the sludge of 32 urban sewage treatment plants in different areas of Shaanxi province were investigated in different water periods. The results indicated that:1) The contents of N, P nutrients and OM in urban sludge in Shaanxi province were abundant, but TK content was not high. The distribution characteristics of the total nutrient content of sludge generally showed the sequence of low water period>flat water period>abundant water period, in which TN and OM contents were very significantly affected by the water period (PJ-T<0.001), while TP and TK contents were not significantly affected by the water period (PJ-T>0.05). 2) The distribution of heavy metal contents in urban sludge of Shaanxi province showed log-normal. The contents sequence of 6 kinds of heavy metals were Zn>Cu>Cr>Pb>Ni>As. There was no significant difference in heavy metals contents of sludge in different water periods (PANOVA>0.05). 3) The urban sludge in Shaanxi province had a high agricultural value and the heavy metal contents in urban sludge in Shaanxi province were generally at a relatively lower level; the sludge was suitable for application in forest land, pasture grassland and cultivated land without growing edible crops; land modification for medium alkaline soil. Meanwhile, special attention should be paid to As content in the sludge.
2020, 38(5): 70-75,83.
doi: 10.13205/j.hjgc.202005013
Abstract:
In order to improve the flow state in the anaerobic reactor, accelerate the granulation of sludge and form an ecological gradient microbial ecosystem, a new type of anaerobic multi-stage spouted bed was designed and fabricated, and the hydraulic spout, gas jet and sludge stratification of the reactor were tested. At room temperature, the mixed sludge was inoculated into a new type of anaerobic multi-stage spouted bed. After 42 days of cultivation, the anaerobic ammonium oxidation reactor was successfully started. Through 18 days of stable operation, the removal rates of NH4+-N and NO2--N were achieved of 90% above. After 60 days of starting, a large amount of granular sludge with particle size of about 2 mm appeared at the bottom of the reactor, which sludge had good stability and sedimentation performance, which sedimentation speed reached 70 m/h. The results showed that the anaerobic multi-stage spouted bed could effectively accelerate the granulation of sludge, due to its special hydraulic structure.
In order to improve the flow state in the anaerobic reactor, accelerate the granulation of sludge and form an ecological gradient microbial ecosystem, a new type of anaerobic multi-stage spouted bed was designed and fabricated, and the hydraulic spout, gas jet and sludge stratification of the reactor were tested. At room temperature, the mixed sludge was inoculated into a new type of anaerobic multi-stage spouted bed. After 42 days of cultivation, the anaerobic ammonium oxidation reactor was successfully started. Through 18 days of stable operation, the removal rates of NH4+-N and NO2--N were achieved of 90% above. After 60 days of starting, a large amount of granular sludge with particle size of about 2 mm appeared at the bottom of the reactor, which sludge had good stability and sedimentation performance, which sedimentation speed reached 70 m/h. The results showed that the anaerobic multi-stage spouted bed could effectively accelerate the granulation of sludge, due to its special hydraulic structure.
2020, 38(5): 76-83.
doi: 10.13205/j.hjgc.202005014
Abstract:
Nitrate-dependent anaerobic ferrous iron oxidation refers to the biomineralization process coupled with ferrous oxidation and nitrate nitrogen reduction, which not only has the effect of denitrification on sewage, but also can obtain a series of iron minerals with strong adsorption and removal ability for multi pollutants. In this study, we constructed a continuous flow biofilm reactor based on this process for wastewater denitrification treatment, and analyzed the characteristics of particulate matters generated internally after three months of operation and their adsorption effect on cadmium (Cd). The results showed that the granules in different positions of the reactor contain different iron minerals, the bottom and middle particles were dominated by siderite, and the top particles were dominated by goethite. These particles had a large specific surface area and a variety of organic functional groups for adsorption, and strong adsorption capacity for Cd2+ in water. The adsorption removal rate of different positions of the reactor was in sequence of effluent>top>middle>bottom, all above 84%. The kinetic and thermodynamic equations complied well with the pseudo second-order model and Freundlich isotherms model, respectively.
Nitrate-dependent anaerobic ferrous iron oxidation refers to the biomineralization process coupled with ferrous oxidation and nitrate nitrogen reduction, which not only has the effect of denitrification on sewage, but also can obtain a series of iron minerals with strong adsorption and removal ability for multi pollutants. In this study, we constructed a continuous flow biofilm reactor based on this process for wastewater denitrification treatment, and analyzed the characteristics of particulate matters generated internally after three months of operation and their adsorption effect on cadmium (Cd). The results showed that the granules in different positions of the reactor contain different iron minerals, the bottom and middle particles were dominated by siderite, and the top particles were dominated by goethite. These particles had a large specific surface area and a variety of organic functional groups for adsorption, and strong adsorption capacity for Cd2+ in water. The adsorption removal rate of different positions of the reactor was in sequence of effluent>top>middle>bottom, all above 84%. The kinetic and thermodynamic equations complied well with the pseudo second-order model and Freundlich isotherms model, respectively.
2020, 38(5): 84-88.
doi: 10.13205/j.hjgc.202005015
Abstract:
A novel magnetic composite adsorbent of PAM@Fe3O4/MnO2 (PFM) was prepared and introduced to remove copper ions from water. The effects of adsorbent dosage, initial concentration of the heavy metal solution, and the adsorption time for the Cu2+ removal were investigated. The experimental results showed that the magnetic composite adsorbent of PFM could effectively remove copper ions from water. Under the conditions of Cu2+ concentration of 50 mg/L, pH of 6.0, and adsorbent dosage of 1.6 g/L, the adsorption equilibrium was gained within 400 min. The adsorption capacity could reach 30.29 mg/g and the removal rate of Cu2+ was as high as 97% then. Adsorption-regeneration cycles confirmed that the adsorbent could be reused successfully for Cu2+ adsorption and had promising potential for practical application. The VSM analysis showed that PFM had the advantages of superparamagnetism and ferromagnetism. The XRD pattern indicated that PAM adhered to the surface of nano-Fe3O4/MnO2, which enhanced the surface area of contact with metal ions in solution and would be beneficial to the adsorption of metal ions. The amide bonds that appeared in the FTIR spectra analysis indicated that magnetic composite adsorbent was successfully prepared by Fe3O4/MnO2 and PAM.
A novel magnetic composite adsorbent of PAM@Fe3O4/MnO2 (PFM) was prepared and introduced to remove copper ions from water. The effects of adsorbent dosage, initial concentration of the heavy metal solution, and the adsorption time for the Cu2+ removal were investigated. The experimental results showed that the magnetic composite adsorbent of PFM could effectively remove copper ions from water. Under the conditions of Cu2+ concentration of 50 mg/L, pH of 6.0, and adsorbent dosage of 1.6 g/L, the adsorption equilibrium was gained within 400 min. The adsorption capacity could reach 30.29 mg/g and the removal rate of Cu2+ was as high as 97% then. Adsorption-regeneration cycles confirmed that the adsorbent could be reused successfully for Cu2+ adsorption and had promising potential for practical application. The VSM analysis showed that PFM had the advantages of superparamagnetism and ferromagnetism. The XRD pattern indicated that PAM adhered to the surface of nano-Fe3O4/MnO2, which enhanced the surface area of contact with metal ions in solution and would be beneficial to the adsorption of metal ions. The amide bonds that appeared in the FTIR spectra analysis indicated that magnetic composite adsorbent was successfully prepared by Fe3O4/MnO2 and PAM.
2020, 38(5): 89-95.
doi: 10.13205/j.hjgc.202005016
Abstract:
xCuO-yWO3/TiO2 catalysts (x and y represent the mass fraction of CuO and WO3 in the sample, respectively) were prepared by sol-gel method and impregnation method, respectively, and the SCR denitration performance (NH3-SCR) of the catalysts was evaluated in a miniature fixed-bed quartz reactor. It was found that the 2CuO-6WO3/TiO2 catalyst by the sol-gel method had good denitration performance, and made NOx conversion rate over 90% in temperature range of 250~350 ℃, which activity was improved significantly compared with 2CuO-6WO3/TiO2 catalyst by impregnation method. The prepared catalysts were characterized by BET, XRD, H2-TPR, NH3-TPD and XPS. The results showed that for the 2CuO-6WO3/TiO2 catalyst prepared by sol-gel method, the specific surface area, the surface adsorbed oxygen, the redox potential and adsorption capacity of NH3 increased significantly than the catalyst prepared by the impregnation method. Therefore, the 2CuO-6WO3/TiO2 catalyst prepared by sol-gel method exhibited excellent NH3-SCR activity and high N2 selectivity.
xCuO-yWO3/TiO2 catalysts (x and y represent the mass fraction of CuO and WO3 in the sample, respectively) were prepared by sol-gel method and impregnation method, respectively, and the SCR denitration performance (NH3-SCR) of the catalysts was evaluated in a miniature fixed-bed quartz reactor. It was found that the 2CuO-6WO3/TiO2 catalyst by the sol-gel method had good denitration performance, and made NOx conversion rate over 90% in temperature range of 250~350 ℃, which activity was improved significantly compared with 2CuO-6WO3/TiO2 catalyst by impregnation method. The prepared catalysts were characterized by BET, XRD, H2-TPR, NH3-TPD and XPS. The results showed that for the 2CuO-6WO3/TiO2 catalyst prepared by sol-gel method, the specific surface area, the surface adsorbed oxygen, the redox potential and adsorption capacity of NH3 increased significantly than the catalyst prepared by the impregnation method. Therefore, the 2CuO-6WO3/TiO2 catalyst prepared by sol-gel method exhibited excellent NH3-SCR activity and high N2 selectivity.
2020, 38(5): 96-101.
doi: 10.13205/j.hjgc.202005017
Abstract:
A series of numerical simulations were conducted for FGD wastewater evaporation occurred in a flue duct of a 2×350 MW coal-fired unit. The evolution and distribution of gas-liquid was revealed and the dependence of residence time and required distance for evaporation on spray parameters and unit load was discussed. The results showed that the liquid droplet could evaporate completely as the droplet diameter was less than 80 μm; while the diameter of liquid droplet increased from 40 μm to 80 μm, the residence time for evaporation increased from 0.26 s to 0.62 s and the required distance for droplet evaporating completely increased from 6.15 m to 13.41 m; the residence time and required distance for evaporation had a linear relation with the droplet diameter. It also presented that enhancing the injection-angle decreased the residence time of evaporation; as the injection-angle was 90°, the required distance of evaporation was the largest; in contrast, when the injection-angle was 120°, the required distance of evaporation was the smallest; while the injection-direction was opposite to the flow direction of flue gas, the residence time of evaporation was the longest and required distance of evaporation was the shortest in the three cases; the residence time of evaporation was larger with a lower load; an obvious increase in the required distance of evaporation was observed with the load dropping from 75% to 50%.
A series of numerical simulations were conducted for FGD wastewater evaporation occurred in a flue duct of a 2×350 MW coal-fired unit. The evolution and distribution of gas-liquid was revealed and the dependence of residence time and required distance for evaporation on spray parameters and unit load was discussed. The results showed that the liquid droplet could evaporate completely as the droplet diameter was less than 80 μm; while the diameter of liquid droplet increased from 40 μm to 80 μm, the residence time for evaporation increased from 0.26 s to 0.62 s and the required distance for droplet evaporating completely increased from 6.15 m to 13.41 m; the residence time and required distance for evaporation had a linear relation with the droplet diameter. It also presented that enhancing the injection-angle decreased the residence time of evaporation; as the injection-angle was 90°, the required distance of evaporation was the largest; in contrast, when the injection-angle was 120°, the required distance of evaporation was the smallest; while the injection-direction was opposite to the flow direction of flue gas, the residence time of evaporation was the longest and required distance of evaporation was the shortest in the three cases; the residence time of evaporation was larger with a lower load; an obvious increase in the required distance of evaporation was observed with the load dropping from 75% to 50%.
2020, 38(5): 102-106.
doi: 10.13205/j.hjgc.202005018
Abstract:
In order to explore the practical application of sintering flue gas purification technology of ozone oxidation combined with magnesium wet absorption, a pilot study on simulated sintering flue gas was carried out. The ultra-low emission route of desulfuration and denitrification by MgO absorption technology was studied and verified by a pilot scale test platform. The results showed that, flue gas volume of 1000 m3/h, SO2 concentration of 1500 mg/m3, NO concentration of 280 mg/m3, smoke temperature of 130 ℃ and n(O3)∶n(NO) above 1.5∶1, the NO oxidation efficiency could reach 100%, the total NOx removal rate of the system reached 90%, and the NOx concentration at the outlet could be maintained in 20~35 mg/m3. The results showed that the application of ozone oxidation-MgO absorption technology in desulfurization and denitrification of sintering flue gas could meet the ultra-low emission standards of sulfur oxides and nitrogen oxides in the iron and steel industry.
In order to explore the practical application of sintering flue gas purification technology of ozone oxidation combined with magnesium wet absorption, a pilot study on simulated sintering flue gas was carried out. The ultra-low emission route of desulfuration and denitrification by MgO absorption technology was studied and verified by a pilot scale test platform. The results showed that, flue gas volume of 1000 m3/h, SO2 concentration of 1500 mg/m3, NO concentration of 280 mg/m3, smoke temperature of 130 ℃ and n(O3)∶n(NO) above 1.5∶1, the NO oxidation efficiency could reach 100%, the total NOx removal rate of the system reached 90%, and the NOx concentration at the outlet could be maintained in 20~35 mg/m3. The results showed that the application of ozone oxidation-MgO absorption technology in desulfurization and denitrification of sintering flue gas could meet the ultra-low emission standards of sulfur oxides and nitrogen oxides in the iron and steel industry.
2020, 38(5): 107-112,119.
doi: 10.13205/j.hjgc.202005019
Abstract:
A series of V2O5-MoO3/TiO2 and V2O5-MoO3/TiO2-ZrO2 catalysts were prepared by impregnation method. The effects of V2O5/TiO2, MoO3/TiO2 and ZrO2/TiO2 mass ratio on the selective catalytic reduction of NO were investigated. The results showed that the V3M6TZ-30% catalyst had the best denitration activity, low SO2 oxidation rate and good sulfur and water resistance. The physical and chemical properties and structure of V3M6T and V3M6TZ-30% catalysts were characterized by XRD, TG, BET, SEM, H2-TPR and NH3-TPD. The results showed that the V3M6TZ-30% catalyst doped with ZrO2 had better selective catalytic reduction of NO activity. This was related to its large specific surface area, sufficient surface hydroxyl groups and weak acid sites, uniform particle size, excellent redox properties.
A series of V2O5-MoO3/TiO2 and V2O5-MoO3/TiO2-ZrO2 catalysts were prepared by impregnation method. The effects of V2O5/TiO2, MoO3/TiO2 and ZrO2/TiO2 mass ratio on the selective catalytic reduction of NO were investigated. The results showed that the V3M6TZ-30% catalyst had the best denitration activity, low SO2 oxidation rate and good sulfur and water resistance. The physical and chemical properties and structure of V3M6T and V3M6TZ-30% catalysts were characterized by XRD, TG, BET, SEM, H2-TPR and NH3-TPD. The results showed that the V3M6TZ-30% catalyst doped with ZrO2 had better selective catalytic reduction of NO activity. This was related to its large specific surface area, sufficient surface hydroxyl groups and weak acid sites, uniform particle size, excellent redox properties.
2020, 38(5): 113-119.
doi: 10.13205/j.hjgc.202005020
Abstract:
Metal elements adsorbed in PM2.5 imposed a great threat to the public health, due to its strong stability and enrichment. In order to characterize the metal elements absorbed in PM2.5, four metropolitan cities with severe haze pollution, i.e., Beijing, Chengdu, Shanghai and Guangzhou, were selected for this study. This paper summarized key studies from 2013 to 2017 related to air pollution, especially PM2.5 and its metal composition in the selected cities. Analysis showed that metal elements in PM2.5 of the selected cities varied both spatially and temporally due to regional meteorological conditions, industrial structures and pollution sources. Secondary aerosols, coal burning and biomass combustion were the three key sources to metal elements in PM2.5 for all the selected cities. While the contributions from other sources varied by cities. The findings implied that the impact of industrial structure on metal elements apportionment in PM2.5 should be further investigated, which would provide insights regarding policy making for effective air pollution control.
Metal elements adsorbed in PM2.5 imposed a great threat to the public health, due to its strong stability and enrichment. In order to characterize the metal elements absorbed in PM2.5, four metropolitan cities with severe haze pollution, i.e., Beijing, Chengdu, Shanghai and Guangzhou, were selected for this study. This paper summarized key studies from 2013 to 2017 related to air pollution, especially PM2.5 and its metal composition in the selected cities. Analysis showed that metal elements in PM2.5 of the selected cities varied both spatially and temporally due to regional meteorological conditions, industrial structures and pollution sources. Secondary aerosols, coal burning and biomass combustion were the three key sources to metal elements in PM2.5 for all the selected cities. While the contributions from other sources varied by cities. The findings implied that the impact of industrial structure on metal elements apportionment in PM2.5 should be further investigated, which would provide insights regarding policy making for effective air pollution control.
2020, 38(5): 120-125,95.
doi: 10.13205/j.hjgc.202005021
Abstract:
In this paper, in order to obtain the law of the influence of relative position of the baffles and the inlet and outlet on the air flow distribution in the bag filter, under the condition of higher negative pressure and higher inlet wind speed, the air flow distribution in the composite bag filter under four different boundary conditions were studied through the CFD numerical simulation method. The results were as the follows: the overall uniformity of flue gas treatment capacity was better when the relative position of air inlet and air outlet was 90°; the guide plate arranged at the lower part of the filter bag, which could not only avoid the impact of activated carbon particles on the filter bag, but also make the overall distribution of the flue gas treatment capacity of the filter bag more uniformed; the closer the filter bag was to the edge of the precipitator, the greater the flue gas treatment capacity was because of the inlet jet effect. This research provided a reference for further optimizing the structure of composite bag filters.
In this paper, in order to obtain the law of the influence of relative position of the baffles and the inlet and outlet on the air flow distribution in the bag filter, under the condition of higher negative pressure and higher inlet wind speed, the air flow distribution in the composite bag filter under four different boundary conditions were studied through the CFD numerical simulation method. The results were as the follows: the overall uniformity of flue gas treatment capacity was better when the relative position of air inlet and air outlet was 90°; the guide plate arranged at the lower part of the filter bag, which could not only avoid the impact of activated carbon particles on the filter bag, but also make the overall distribution of the flue gas treatment capacity of the filter bag more uniformed; the closer the filter bag was to the edge of the precipitator, the greater the flue gas treatment capacity was because of the inlet jet effect. This research provided a reference for further optimizing the structure of composite bag filters.
2020, 38(5): 126-132.
doi: 10.13205/j.hjgc.202005022
Abstract:
In order to explore the magnetic response of environmental pollution about dust-loaded leaves on main road in Baoji city, different types of leaves on both sides of streets were collected for systematic environmental magnetic tests. The results showed that the concentration of magnetic minerals on street leaves were higher than that in the campus and the main magnetic minerals were multi-domain magnetite and maghemite. The diameter of magnetic mineral was concentrated in 0.1~5 μm, among which the herbaceous far from the traffic lines had a relatively fineer particle size of 0.1~1 μm. Environmental pollution recorded by vegetation leaves at the same height and at different times (May and November) was different. Pollution recorded by herbaceous at 0.05 m height and trees leaves at 4 m height was more serious in May than in November, while that of the leaves of shrubs at 0.25 m and 1 m was worse in November. The spatial distribution of urban main roads presented two pollution peak areas, the zone A including Jiangtan road and Baofu road, and the zone B where Dongfeng road was located in, which are related to heavy traffic and heavy industrial enterprises.
In order to explore the magnetic response of environmental pollution about dust-loaded leaves on main road in Baoji city, different types of leaves on both sides of streets were collected for systematic environmental magnetic tests. The results showed that the concentration of magnetic minerals on street leaves were higher than that in the campus and the main magnetic minerals were multi-domain magnetite and maghemite. The diameter of magnetic mineral was concentrated in 0.1~5 μm, among which the herbaceous far from the traffic lines had a relatively fineer particle size of 0.1~1 μm. Environmental pollution recorded by vegetation leaves at the same height and at different times (May and November) was different. Pollution recorded by herbaceous at 0.05 m height and trees leaves at 4 m height was more serious in May than in November, while that of the leaves of shrubs at 0.25 m and 1 m was worse in November. The spatial distribution of urban main roads presented two pollution peak areas, the zone A including Jiangtan road and Baofu road, and the zone B where Dongfeng road was located in, which are related to heavy traffic and heavy industrial enterprises.
2020, 38(5): 133-137,106.
doi: 10.13205/j.hjgc.202005023
Abstract:
Steel slag production quantity is huge in China. With the increasingly strict environmental protection requirements in China, the modification of steel slag to make steel slag resource utilization becomes an urgent task. This paper briefly described the characteristics of the steel slag and the problems of resource utilization. The research progress of steel slag modification was reviewed. Combined with the characteristics of the existing steel slag modification process, the paper pointed out that the hot steel slag carbonation modification could not only make full use of the huge thermal energy of the steel slag itself, but also achieve the reduction of CO2 emission in steel plant, and realize the improvement of steel slag stability and gelation performance. Therefore, the process was also the development direction of steel slag modification in the future.
Steel slag production quantity is huge in China. With the increasingly strict environmental protection requirements in China, the modification of steel slag to make steel slag resource utilization becomes an urgent task. This paper briefly described the characteristics of the steel slag and the problems of resource utilization. The research progress of steel slag modification was reviewed. Combined with the characteristics of the existing steel slag modification process, the paper pointed out that the hot steel slag carbonation modification could not only make full use of the huge thermal energy of the steel slag itself, but also achieve the reduction of CO2 emission in steel plant, and realize the improvement of steel slag stability and gelation performance. Therefore, the process was also the development direction of steel slag modification in the future.
2020, 38(5): 138-143.
doi: 10.13205/j.hjgc.202005024
Abstract:
The disposal of construction waste is still a worldwide problem, and currently its main disposal method is still traditional landfill in China, leading to occupation of land, soil and groundwater pollution, release of greenhouse gas methane and other environmental problems. The implementation of the concept of cleaner production in the whole process of construction industry is the fundamental measure to solve these problems because it’s generated in construction industry. The current situation and development trend of the construction waste was investigated. The main measures for the waste management involved in reduction of waste in source and construction, waste utilization and etc., which would be achieved by utilization of advanced construction technology, establishment of perfect law system, enhancement of construction and in situ utilization of the waste, according to the principle of avoiding generation, reducing as much as possible, resource utilization and safe disposal. Ultimately, the amount of construction waste shipped to the disposal site could be reduced. In China, the utilization of construction waste in road materials is with consideration.
The disposal of construction waste is still a worldwide problem, and currently its main disposal method is still traditional landfill in China, leading to occupation of land, soil and groundwater pollution, release of greenhouse gas methane and other environmental problems. The implementation of the concept of cleaner production in the whole process of construction industry is the fundamental measure to solve these problems because it’s generated in construction industry. The current situation and development trend of the construction waste was investigated. The main measures for the waste management involved in reduction of waste in source and construction, waste utilization and etc., which would be achieved by utilization of advanced construction technology, establishment of perfect law system, enhancement of construction and in situ utilization of the waste, according to the principle of avoiding generation, reducing as much as possible, resource utilization and safe disposal. Ultimately, the amount of construction waste shipped to the disposal site could be reduced. In China, the utilization of construction waste in road materials is with consideration.
2020, 38(5): 144-149.
doi: 10.13205/j.hjgc.202005025
Abstract:
The anaerobic biodegradability and methane yield of the low organic municipal sludge could be significantly improved on anaerobic co-digestion, by combing banana straw with high temperature thermal hydrolysis pretreatment (HTHP). In the combining system of anaerobic co-digestion and HTHP, the methane yield of municipal sludge, banana straw and their mixture were 388, 372, 537mL/gVS, respectively, which showed the significant synergistic effect. In their own optimal pretreatment condition of sludge, banana straw and their mixture, the T80 was 12, 19, 17 days, respectively, which could be represented as hydraulic retention time of anaerobic digestion; SCOD dissolution ratio was respectively 14.4, 2.8, and 5.9 times of those before pretreatment; SCOD removal rate was 93.7%, 89.8% and 94.5% after anaerobic digestion, and the removal rate of VS was 48.4%, 48.8% and 59.2%, respectively. The concentration of soluble protein, VFA and soluble polysaccharide were increased significantly, which was 14.5, 5.1 and 8.2 times of that before HTTP, and the removal rate was 94.4%, 94.9% and 95.2% in the subsequent anaerobic digestion stage, which was slightly higher than single treatment.
The anaerobic biodegradability and methane yield of the low organic municipal sludge could be significantly improved on anaerobic co-digestion, by combing banana straw with high temperature thermal hydrolysis pretreatment (HTHP). In the combining system of anaerobic co-digestion and HTHP, the methane yield of municipal sludge, banana straw and their mixture were 388, 372, 537mL/gVS, respectively, which showed the significant synergistic effect. In their own optimal pretreatment condition of sludge, banana straw and their mixture, the T80 was 12, 19, 17 days, respectively, which could be represented as hydraulic retention time of anaerobic digestion; SCOD dissolution ratio was respectively 14.4, 2.8, and 5.9 times of those before pretreatment; SCOD removal rate was 93.7%, 89.8% and 94.5% after anaerobic digestion, and the removal rate of VS was 48.4%, 48.8% and 59.2%, respectively. The concentration of soluble protein, VFA and soluble polysaccharide were increased significantly, which was 14.5, 5.1 and 8.2 times of that before HTTP, and the removal rate was 94.4%, 94.9% and 95.2% in the subsequent anaerobic digestion stage, which was slightly higher than single treatment.
2020, 38(5): 150-154.
doi: 10.13205/j.hjgc.202005026
Abstract:
With the rapid development of Chinese economy and urbanization, sludge production in sewage treatment plants rises rapidly. It is very important to properly dispose of the sludge. The preparation of sludge-based foam insulation materials can utilize the sludge to meet the needs of Chinese sustainable development strategy. The type and proportion of the foaming agent were studied to determine the optimum material compositon and proportion. On this basis, orthogonal experiments were carried out to optimized the preparation process of sludge-based foam insulation materials. The effects of sludge addition, cement addition and water-solid ratio on the properties of foaming insulation materials were studied, and the preparation process was optimized. The results showed that OP emulsifier-10 of 0.6% and cellulose ether of 0.3% were the best for foaming. Through comprehensive analysis of multiple performance indicators, it was concluded that the order of the influencing factors of sludge-based foaming insulation material preparation was water-solid ratio>sludge addition>cement addition. The optimum ratio of raw materials was sludge of 12.5%, cement of 55.5%, water-solid ratio of 0.5. Under this optimum ratio, density, compressive strength and thermal conductivity of the prepared insulation materials were 624.4 kg/m3, 0.32 MPa and 0.072 W/(m·K), respectively, which met the requirements of national standard for density A07, compressive strength C0.3 for inorganic foaming materials (JG/T 266—2014).
With the rapid development of Chinese economy and urbanization, sludge production in sewage treatment plants rises rapidly. It is very important to properly dispose of the sludge. The preparation of sludge-based foam insulation materials can utilize the sludge to meet the needs of Chinese sustainable development strategy. The type and proportion of the foaming agent were studied to determine the optimum material compositon and proportion. On this basis, orthogonal experiments were carried out to optimized the preparation process of sludge-based foam insulation materials. The effects of sludge addition, cement addition and water-solid ratio on the properties of foaming insulation materials were studied, and the preparation process was optimized. The results showed that OP emulsifier-10 of 0.6% and cellulose ether of 0.3% were the best for foaming. Through comprehensive analysis of multiple performance indicators, it was concluded that the order of the influencing factors of sludge-based foaming insulation material preparation was water-solid ratio>sludge addition>cement addition. The optimum ratio of raw materials was sludge of 12.5%, cement of 55.5%, water-solid ratio of 0.5. Under this optimum ratio, density, compressive strength and thermal conductivity of the prepared insulation materials were 624.4 kg/m3, 0.32 MPa and 0.072 W/(m·K), respectively, which met the requirements of national standard for density A07, compressive strength C0.3 for inorganic foaming materials (JG/T 266—2014).
2020, 38(5): 155-159,178.
doi: 10.13205/j.hjgc.202005027
Abstract:
In our study, five kinds of red mud samples from different aluminum factories were collected for sequencing batch leaching experiment to simulate the leaching behavior of rare metals of red mud in natural storage condition under different pH. The results showed that the leaching rates of La, Sc and Y decreased with the increase of pH, reached 45%, 82% and 64% respectively under extremely acidic conditions (2
In our study, five kinds of red mud samples from different aluminum factories were collected for sequencing batch leaching experiment to simulate the leaching behavior of rare metals of red mud in natural storage condition under different pH. The results showed that the leaching rates of La, Sc and Y decreased with the increase of pH, reached 45%, 82% and 64% respectively under extremely acidic conditions (2
2020, 38(5): 160-164,214.
doi: 10.13205/j.hjgc.202005028
Abstract:
In order to expand the utilization of activated sludge, the co-pyrolysis of sludge and wheat straw with different moisture content was studied in a fixed bed reactor. Sludge and straw with different moisture content were mixed and pyrolysis in the range of 600~900 ℃. The effects of pyrolysis temperature, sludge moisture content and straw addition amount on gas composition were studied. When the sludge moisture content was constant, the content of H2 and CO gradually increased with the increase of reactor temperature. At the same temperature, as the moisture content of sludge increased, the content of H2 increased first and then decreased, while the content of CO decreased gradually. When the moisture content of sludge was 60%, the content of H2 reached the maximum value. When the pyrolysis temperature was 800 ℃, 40% straw and sludge with moisture content of 60% was the best proportion to prepare hydrogen-rich syngas.
In order to expand the utilization of activated sludge, the co-pyrolysis of sludge and wheat straw with different moisture content was studied in a fixed bed reactor. Sludge and straw with different moisture content were mixed and pyrolysis in the range of 600~900 ℃. The effects of pyrolysis temperature, sludge moisture content and straw addition amount on gas composition were studied. When the sludge moisture content was constant, the content of H2 and CO gradually increased with the increase of reactor temperature. At the same temperature, as the moisture content of sludge increased, the content of H2 increased first and then decreased, while the content of CO decreased gradually. When the moisture content of sludge was 60%, the content of H2 reached the maximum value. When the pyrolysis temperature was 800 ℃, 40% straw and sludge with moisture content of 60% was the best proportion to prepare hydrogen-rich syngas.
2020, 38(5): 165-170.
doi: 10.13205/j.hjgc.202005029
Abstract:
In this study, the remediation effect of several chemical oxidation systems on TPH-contaminated soils were evaluated, and some impact factors were studied as well. The results showed that Fenton, Fenton-like and alkali-activated persulfate systems showed good TPH remediation performance. Since the addition of citric acid significantly improved the catalytic activity of Fenton system, the Fenton-like system showed the best TPH degradation performance. The TPH degradation in Fenton-like and alkali-activated persulfate systems followed the pseudo-first-order kinetics. Increasing the concentration of hydrogen peroxide, citric acid and persulfate could enhance the degradation of TPH. It was proved that intensifying mixing, adopting sequential addition of oxidants and reducing soil particle size could obviously improve the degradation effect of TPH with lower amount of oxidants. Moreover, the experimental results confirmed that the main active free radical in Fenton-like system was ·OH, while in the alkali-activated persulfate system, besides ·OH, the presence of SO4-· or O2-·, and other presenting free radicals also made greater advantage of the oxidants.
In this study, the remediation effect of several chemical oxidation systems on TPH-contaminated soils were evaluated, and some impact factors were studied as well. The results showed that Fenton, Fenton-like and alkali-activated persulfate systems showed good TPH remediation performance. Since the addition of citric acid significantly improved the catalytic activity of Fenton system, the Fenton-like system showed the best TPH degradation performance. The TPH degradation in Fenton-like and alkali-activated persulfate systems followed the pseudo-first-order kinetics. Increasing the concentration of hydrogen peroxide, citric acid and persulfate could enhance the degradation of TPH. It was proved that intensifying mixing, adopting sequential addition of oxidants and reducing soil particle size could obviously improve the degradation effect of TPH with lower amount of oxidants. Moreover, the experimental results confirmed that the main active free radical in Fenton-like system was ·OH, while in the alkali-activated persulfate system, besides ·OH, the presence of SO4-· or O2-·, and other presenting free radicals also made greater advantage of the oxidants.
2020, 38(5): 171-178.
doi: 10.13205/j.hjgc.202005030
Abstract:
Mercury (Hg) pollution has become one of the most important environmental problems because of its high toxicity, wide range of pollution and high risk of ecological health. The anthropogenic sources of mercury pollution mainly include fossil fuel combustion, mineral exploitation and processing, waste incineration and production and use of mercury related products. Bioremediation has a good prospective application in the treatment and remediation of mercury contamination due to their advantages of low cost, easy operation and ecological friendliness. This paper reviews the main sources and current situation of mercury pollution in the environment, and summarizes the application and mechanism of eco-friendly technology based on the action of plants and microorganisms in the remediation of mercury polluted soil and water. Furthermore, the relevant issues that should be further studied and practiced in bioremediation of mercury pollution have also been proposed. The main purpose of this paper is to provide a scientific reference for bioremediation of mercury pollution.
Mercury (Hg) pollution has become one of the most important environmental problems because of its high toxicity, wide range of pollution and high risk of ecological health. The anthropogenic sources of mercury pollution mainly include fossil fuel combustion, mineral exploitation and processing, waste incineration and production and use of mercury related products. Bioremediation has a good prospective application in the treatment and remediation of mercury contamination due to their advantages of low cost, easy operation and ecological friendliness. This paper reviews the main sources and current situation of mercury pollution in the environment, and summarizes the application and mechanism of eco-friendly technology based on the action of plants and microorganisms in the remediation of mercury polluted soil and water. Furthermore, the relevant issues that should be further studied and practiced in bioremediation of mercury pollution have also been proposed. The main purpose of this paper is to provide a scientific reference for bioremediation of mercury pollution.
2020, 38(5): 179-184.
doi: 10.13205/j.hjgc.202005031
Abstract:
Through the indoor simulation experiments, the effect of environmental factors on the release and conversion of OP in the sediment was studied. The results were gained as follows: the combining capping of river sand and red soil was the best way to control the release of OP in sediment; under the aerobic environment with T=25 ℃, the combination of sand and red soil capping can effectively control the release of organic phosphorus into the overlying water, and the content of OP in sediment increased, reducing the concentration of TP and DOP in overlying water. The environmental factors had the considerable impact on the conversion of moderately active phosphorus (MLOP) in the sediment, and the content of organic phosphorus and the ratio of OP/TP increased from inhibiting the MLOP conversion in the sediment. The correlation between alkaline phosphatase activity (APA) and various forms of phosphorus in the sediment showed that APA was positively correlated with TP and OP content in sediment, and APA could indicate the conversion process between various forms of phosphorus.
Through the indoor simulation experiments, the effect of environmental factors on the release and conversion of OP in the sediment was studied. The results were gained as follows: the combining capping of river sand and red soil was the best way to control the release of OP in sediment; under the aerobic environment with T=25 ℃, the combination of sand and red soil capping can effectively control the release of organic phosphorus into the overlying water, and the content of OP in sediment increased, reducing the concentration of TP and DOP in overlying water. The environmental factors had the considerable impact on the conversion of moderately active phosphorus (MLOP) in the sediment, and the content of organic phosphorus and the ratio of OP/TP increased from inhibiting the MLOP conversion in the sediment. The correlation between alkaline phosphatase activity (APA) and various forms of phosphorus in the sediment showed that APA was positively correlated with TP and OP content in sediment, and APA could indicate the conversion process between various forms of phosphorus.
2020, 38(5): 191-195.
doi: 10.13205/j.hjgc.202005033
Abstract:
In the process of landfill stabilization, to study the influencing factors of anaerobic methane oxidation process, the influence of gaseous substances (hydrogen, nitrogen) on the anaerobic methane oxidation process was investigated. On this basis, the effect of simulated gas on the anaerobic methane degradation process and microbial population structure were clarified. The results showed that there were cycle processes of methane oxidation, nitrogen fixation, nitrification and denitrification under atmospheric nitrogen, while the introduction of hydrogen had a certain impact on the degradation process of anaerobic methane. The methane concentration decreased firstly, then increased and then decreased, and the carbon dioxide concentration first increased then decreased, which was due to the reduction of carbon dioxide by hydrogen. After the long-term domestication of nitrogen and hydrogen, the structures of the soil microbial community changed significantly, and the amount of bacteria with nitrification, denitrification and nitrogen fixation function increased, and the Methylococcale appeared. The consumption of oxygen by aerobic bacteria (such as methane oxidizing bacteria and nitrifying bacteria) was conducive to the process of denitrification and anaerobic methane oxidation, which provided favorable condition for the occurrence of anaerobic methane oxidation. The results revealed the influence of gaseous substances on the anaerobic methane oxidation process during landfill stabilization.
In the process of landfill stabilization, to study the influencing factors of anaerobic methane oxidation process, the influence of gaseous substances (hydrogen, nitrogen) on the anaerobic methane oxidation process was investigated. On this basis, the effect of simulated gas on the anaerobic methane degradation process and microbial population structure were clarified. The results showed that there were cycle processes of methane oxidation, nitrogen fixation, nitrification and denitrification under atmospheric nitrogen, while the introduction of hydrogen had a certain impact on the degradation process of anaerobic methane. The methane concentration decreased firstly, then increased and then decreased, and the carbon dioxide concentration first increased then decreased, which was due to the reduction of carbon dioxide by hydrogen. After the long-term domestication of nitrogen and hydrogen, the structures of the soil microbial community changed significantly, and the amount of bacteria with nitrification, denitrification and nitrogen fixation function increased, and the Methylococcale appeared. The consumption of oxygen by aerobic bacteria (such as methane oxidizing bacteria and nitrifying bacteria) was conducive to the process of denitrification and anaerobic methane oxidation, which provided favorable condition for the occurrence of anaerobic methane oxidation. The results revealed the influence of gaseous substances on the anaerobic methane oxidation process during landfill stabilization.
2020, 38(5): 196-201,222.
doi: 10.13205/j.hjgc.202005034
Abstract:
In order to study the pollution characteristics of polycyclic aromatic hydrocarbons (PAHs) in urban top soil of Shenyang, 74 urban top soil samples were collected from the urban area of Shenyang in September 2017, the concentrations of 16 prior PAHs were determined, and the health risks were evaluated by probabilistic risk models based on Monte Carlo simulation. The results showed that, the concentrations of 16 PAHs ranged from 283 to 21821 μg/kg, with an average concentration of 2370 μg/kg. Compared with other researches, the pollution extent of PAHs in urban top soil of Shenyang was serious. The results of health risk assessment showed that, the total carcinogenic and non-carcinogenic risks caused by PAHs for children and adults were presented at an acceptable level. Among them, benzo[a]pyrene was the key contributor for carcinogenic risk, while pyrene, fluoranthene and phenanthrene were the key contributors for non-carcinogenic risk.
In order to study the pollution characteristics of polycyclic aromatic hydrocarbons (PAHs) in urban top soil of Shenyang, 74 urban top soil samples were collected from the urban area of Shenyang in September 2017, the concentrations of 16 prior PAHs were determined, and the health risks were evaluated by probabilistic risk models based on Monte Carlo simulation. The results showed that, the concentrations of 16 PAHs ranged from 283 to 21821 μg/kg, with an average concentration of 2370 μg/kg. Compared with other researches, the pollution extent of PAHs in urban top soil of Shenyang was serious. The results of health risk assessment showed that, the total carcinogenic and non-carcinogenic risks caused by PAHs for children and adults were presented at an acceptable level. Among them, benzo[a]pyrene was the key contributor for carcinogenic risk, while pyrene, fluoranthene and phenanthrene were the key contributors for non-carcinogenic risk.
2020, 38(5): 202-209.
doi: 10.13205/j.hjgc.202005035
Abstract:
In Lianhua Town, the suburb of Changsha, 54 soil samples were collected, and the contents of 5 heavy metal elements including Hg, Cd, As, Pb and Cr, were measured. A comprehensive ecological risk evaluation method was used to evaluate the pollution degree of heavy metal elements in soils and their harm to human health. The results were as follows: 1) The average contents of Cd, Hg and Pb exceeded more than 1 time of the soil background value in Hunan province, and the accumulation in the soil was more obvious; the spatial variation of Cd and Pb was significant, indicating that their sources were highly disturbed; and the pollution degree of the 5 heavy metal elements was in sequence of Cd>Hg>Pb>As>Cr. 2) The potential ecological hazard of the 5 kinds of heavy metals was in sequence of Cd>Hg>As>Pb>Cr, and Cd and Hg possessed strong ecological hazards. The average value of the comprehensive potential ecological risk index had reached strong level. Cd and Hg were the main contributors in the study regional soil pollution. 3) "Hand-mouth" intake was the main way of soil heavy metal exposure. The non-carcinogenic exposure dose for children was far greater than that of the adults; the non-carcinogenic risk were within the safe limits. 4) The risk index of Cr was as hjgh as 10-4 above, with carcinogenic risk; carcinogenic risk index of Cd and As ranged in 10-6~10-4, within an acceptable risk range. The pollution of As and Cr was found as the major factors affecting human health, and should be paid more attention to.
In Lianhua Town, the suburb of Changsha, 54 soil samples were collected, and the contents of 5 heavy metal elements including Hg, Cd, As, Pb and Cr, were measured. A comprehensive ecological risk evaluation method was used to evaluate the pollution degree of heavy metal elements in soils and their harm to human health. The results were as follows: 1) The average contents of Cd, Hg and Pb exceeded more than 1 time of the soil background value in Hunan province, and the accumulation in the soil was more obvious; the spatial variation of Cd and Pb was significant, indicating that their sources were highly disturbed; and the pollution degree of the 5 heavy metal elements was in sequence of Cd>Hg>Pb>As>Cr. 2) The potential ecological hazard of the 5 kinds of heavy metals was in sequence of Cd>Hg>As>Pb>Cr, and Cd and Hg possessed strong ecological hazards. The average value of the comprehensive potential ecological risk index had reached strong level. Cd and Hg were the main contributors in the study regional soil pollution. 3) "Hand-mouth" intake was the main way of soil heavy metal exposure. The non-carcinogenic exposure dose for children was far greater than that of the adults; the non-carcinogenic risk were within the safe limits. 4) The risk index of Cr was as hjgh as 10-4 above, with carcinogenic risk; carcinogenic risk index of Cd and As ranged in 10-6~10-4, within an acceptable risk range. The pollution of As and Cr was found as the major factors affecting human health, and should be paid more attention to.
2020, 38(5): 210-214.
doi: 10.13205/j.hjgc.202005036
Abstract:
In order to quickly and accurately determine the total nitrogen content in maize leaves and monitor the nitrogen element content under microbial remediation by hyperspectral remote sensing technology, two levels of AM fungal treatment were set up, with(M) and without (CK) arbuscular mycorrhizal Fungi inoculated. The physicochemical parameters and spectral reflectance data of leaves under the two treatments were measured respectively, and the effects of AM fungi inoculation on maize were studied. Stepwise regression method was used to model and retrieve the total nitrogen content of leaves. The results showed that inoculating AM fungi could increase the contents of total nitrogen, total phosphorus, total potassium and chlorophyll in leaves at different leaf positions, and significantly increase the biomass and leaf water content of maize. The correlation of total nitrogen content in different treatments was similar to that in different characteristic parameters, but the correlation coefficients were different. The stepwise linear regression method was used to estimate the nitrogen content of maize leaves by using the nine extremely significant spectral parameters as independent variables. Among them, the model determination coefficient R2 in CK was up to 0.8361, and the determination coefficient of M model was up to 0.893, which could estimate the total nitrogen content of maize leaves.
In order to quickly and accurately determine the total nitrogen content in maize leaves and monitor the nitrogen element content under microbial remediation by hyperspectral remote sensing technology, two levels of AM fungal treatment were set up, with(M) and without (CK) arbuscular mycorrhizal Fungi inoculated. The physicochemical parameters and spectral reflectance data of leaves under the two treatments were measured respectively, and the effects of AM fungi inoculation on maize were studied. Stepwise regression method was used to model and retrieve the total nitrogen content of leaves. The results showed that inoculating AM fungi could increase the contents of total nitrogen, total phosphorus, total potassium and chlorophyll in leaves at different leaf positions, and significantly increase the biomass and leaf water content of maize. The correlation of total nitrogen content in different treatments was similar to that in different characteristic parameters, but the correlation coefficients were different. The stepwise linear regression method was used to estimate the nitrogen content of maize leaves by using the nine extremely significant spectral parameters as independent variables. Among them, the model determination coefficient R2 in CK was up to 0.8361, and the determination coefficient of M model was up to 0.893, which could estimate the total nitrogen content of maize leaves.
2020, 38(5): 215-222.
doi: 10.13205/j.hjgc.202005037
Abstract:
Groundwater pollution risk assessment is important for the rational development and utilization of land and groundwater pollution prevention. By analyzing the characteristics of shallow groundwater in the plain area of Xi’an, a conceptual model of groundwater pollution risk assessment including groundwater vulnerability, pollution source load and water function value was established, and the groundwater pollution risk of the plain area of Xi’an was evaluated. The results showed that the high, medium and low risk areas of groundwater pollution in the plain area of Xi’an accounted for 0.2%, 28.8% and 71.1% of the total study area, respectively. The medium and above risk areas of groundwater pollution in the plain area were mainly distributed along the banks of the Weihe River in Zhouzhi County, along the Weihe River in Chang’an District, and along the Weihe River in Lantian County. The high groundwater vulnerability and relatively strong pollution source load were the main reasons for the relatively high pollution risk in the region.
Groundwater pollution risk assessment is important for the rational development and utilization of land and groundwater pollution prevention. By analyzing the characteristics of shallow groundwater in the plain area of Xi’an, a conceptual model of groundwater pollution risk assessment including groundwater vulnerability, pollution source load and water function value was established, and the groundwater pollution risk of the plain area of Xi’an was evaluated. The results showed that the high, medium and low risk areas of groundwater pollution in the plain area of Xi’an accounted for 0.2%, 28.8% and 71.1% of the total study area, respectively. The medium and above risk areas of groundwater pollution in the plain area were mainly distributed along the banks of the Weihe River in Zhouzhi County, along the Weihe River in Chang’an District, and along the Weihe River in Lantian County. The high groundwater vulnerability and relatively strong pollution source load were the main reasons for the relatively high pollution risk in the region.
