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2020 Vol. 38, No. 6
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2020, 38(6): 1-8,23.
doi: 10.13205/j.hjgc.202006001
Abstract:
The contamination of hexavalent chromium in the soil mainly derives from chromium-related industries such as chromium chemical industry, electroplating, tanning and so on. This paper briefly described the general situation of chromium industry in China, as well as the source and characteristics of chromium-contaminated soil. The research and application progress of remediation technology for chromium-contaminated site at home and abroad were reviewed, including the contrastive analysis of various remediation methods. Additionally, remediation engineering cases were also listed and analysed in this paper. China has a powerful chromium salts production industry which brings about seriously pollution of chromium in soil. The electroplated chromium-contaminated site presented the characteristics of chromium-nickel-copper-zinc composite pollution. The tannery chromium contaminated site had the characteristic of combined pollution of chromium and organic compounds. At present, the remediation technology of chromium-contaminated soil was mainly based on the principle of reduction and stabilization of hexavalent chromium, including chemical reduction, chemical leaching, electrokinetic remediation, biological remediation technology and so on. Considering the technical applicability and economy, most of the chromium-contaminated soil remediation projects currently employed chemical reduction remediation technology. As for the development of chromium-contaminated site remediation technology, preparing cheap and environmentally friendly remediation materials, as well as discussing the remediation mechanism and long-term safety would be the potential research hotpots.
The contamination of hexavalent chromium in the soil mainly derives from chromium-related industries such as chromium chemical industry, electroplating, tanning and so on. This paper briefly described the general situation of chromium industry in China, as well as the source and characteristics of chromium-contaminated soil. The research and application progress of remediation technology for chromium-contaminated site at home and abroad were reviewed, including the contrastive analysis of various remediation methods. Additionally, remediation engineering cases were also listed and analysed in this paper. China has a powerful chromium salts production industry which brings about seriously pollution of chromium in soil. The electroplated chromium-contaminated site presented the characteristics of chromium-nickel-copper-zinc composite pollution. The tannery chromium contaminated site had the characteristic of combined pollution of chromium and organic compounds. At present, the remediation technology of chromium-contaminated soil was mainly based on the principle of reduction and stabilization of hexavalent chromium, including chemical reduction, chemical leaching, electrokinetic remediation, biological remediation technology and so on. Considering the technical applicability and economy, most of the chromium-contaminated soil remediation projects currently employed chemical reduction remediation technology. As for the development of chromium-contaminated site remediation technology, preparing cheap and environmentally friendly remediation materials, as well as discussing the remediation mechanism and long-term safety would be the potential research hotpots.
2020, 38(6): 9-15.
doi: 10.13205/j.hjgc.202006002
Abstract:
It is becoming increasingly prominent of the problem of chromium contaminated of groundwater in China. It is extremely urgent to remediate the chromium contaminated groundwater. Permeable reactive barrier (PRB) is a new type of in-situ contaminated groundwater remediation technology, which can implement continuous in-situ remediation of chromium contaminated groundwater. Important factors were summarized in this review, which included the commonly used reactive fillers, key design parameters and construction technologies of PRB for chromium contaminated groundwater remediation. Accordingly, the main problems and prospects in the process of engineering application of PRB technology were briefly analyzed.
It is becoming increasingly prominent of the problem of chromium contaminated of groundwater in China. It is extremely urgent to remediate the chromium contaminated groundwater. Permeable reactive barrier (PRB) is a new type of in-situ contaminated groundwater remediation technology, which can implement continuous in-situ remediation of chromium contaminated groundwater. Important factors were summarized in this review, which included the commonly used reactive fillers, key design parameters and construction technologies of PRB for chromium contaminated groundwater remediation. Accordingly, the main problems and prospects in the process of engineering application of PRB technology were briefly analyzed.
2020, 38(6): 16-23.
doi: 10.13205/j.hjgc.202006003
Abstract:
Chemical reduction stabilization remediation is the most widely used technology for remediation of chromium contaminated soils. How to select the most efficient, economical and applicable remediation materials for chromium-contaminated soil with different pollution degrees and physicochemical properties is the core problem of chromium-contaminated soil remediation engineering. This paper mainly focused on the remediation principles, influencing factors, the actual application effect and the existing problems, the environmental risk and long-term stability of chromium-contaminated soil remediation materials, such as iron-based, sulfur-based, iron-sulfur-based, organic and microbial agents, to the reduction of hexavalent chromium-contaminated soil. It can provide references and guidance for better application of those remediation materials in the practical engineering.
Chemical reduction stabilization remediation is the most widely used technology for remediation of chromium contaminated soils. How to select the most efficient, economical and applicable remediation materials for chromium-contaminated soil with different pollution degrees and physicochemical properties is the core problem of chromium-contaminated soil remediation engineering. This paper mainly focused on the remediation principles, influencing factors, the actual application effect and the existing problems, the environmental risk and long-term stability of chromium-contaminated soil remediation materials, such as iron-based, sulfur-based, iron-sulfur-based, organic and microbial agents, to the reduction of hexavalent chromium-contaminated soil. It can provide references and guidance for better application of those remediation materials in the practical engineering.
2020, 38(6): 24-27,57.
doi: 10.13205/j.hjgc.202006004
Abstract:
In order to study the pollution situation of a typical tannery sludge yard area, a tannery sludge yard in Haining, Zhejiang Province was taken as the research object to study the pollution of organic matters and heavy metals in the soil and groundwater of the tannery sludge yard. The survey results showed that the inorganic pollution in the soil was slight, and the total chromium, hexavalent chromium and lead content were relatively higher. The lead and total chromium concentration in the contaminated soil were 2.82 times and 7.03 times of the specified value of industrial land respectively, and the maximum content of hexavalent chromium was 2.8 times of the control value. The ammonia nitrogen content in groundwater exceeded the standard seriously, reaching 1268.0 mg/L, which was 845.3 times of the lower limit of category V water quality for industrial and agricultural use, and the content of hexavalent chromium was less than 0.004 mg/L. In addition, the vertical distribution of hexavalent chromium and total chromium content at each sampling point showed a large difference, which was also different from the vertical distribution of heavy metals in some tannery sludge yards.
In order to study the pollution situation of a typical tannery sludge yard area, a tannery sludge yard in Haining, Zhejiang Province was taken as the research object to study the pollution of organic matters and heavy metals in the soil and groundwater of the tannery sludge yard. The survey results showed that the inorganic pollution in the soil was slight, and the total chromium, hexavalent chromium and lead content were relatively higher. The lead and total chromium concentration in the contaminated soil were 2.82 times and 7.03 times of the specified value of industrial land respectively, and the maximum content of hexavalent chromium was 2.8 times of the control value. The ammonia nitrogen content in groundwater exceeded the standard seriously, reaching 1268.0 mg/L, which was 845.3 times of the lower limit of category V water quality for industrial and agricultural use, and the content of hexavalent chromium was less than 0.004 mg/L. In addition, the vertical distribution of hexavalent chromium and total chromium content at each sampling point showed a large difference, which was also different from the vertical distribution of heavy metals in some tannery sludge yards.
2020, 38(6): 28-34.
doi: 10.13205/j.hjgc.202006005
Abstract:
Biochar attracted more and more attention as a processing adsorbent of heavy metals in the field of environmental protection, due to its wide source of raw materials, abundant active functional groups in surface, and stable physical and chemical properties. In this work, pine sawdust was used to synthesize biochar at a carbonization temperature of 400 ℃(AB400) by using HNO3, H3PO4, NH3 · H2O, Ca (OH)2 as the modification agent of the biochar. SEM, FTIR, Boehm titration method and Zeta potential determination were adopted to characteriza Biochar AB400. And Cr(Ⅵ) adsorption experiment was conducted. After modification, the structure of biochar appeared semi-penetrating to penetrating round collapse with micropores. Under the conditions of acid modification, the content of intermediate acid functional groups of AB400HNO3 and AB400H3PO4 increased, and the pH values of biochar decreased, corresponding to the increase in pHpzc value. As for the Cr(Ⅵ) adsorption, the overall adsorption performance of the acid modified biochar was better than that of alkaline modified biochar, and AB400H3PO4 achieved the best adsorption performance with an adsorption capacity increased from 58.48 mg/g to 101.82 mg/g. This was probably because the surface of alkaline modified biochar was negatively charged and repulsive to the oxygen-containing anions of Cr(Ⅵ). AB400HNO3 had smaller volume of micropores and a smaller number of round collapses than AB400H3PO4. Although the surface of AB400HNO3 was also positively charged, its adsorption performance was not as good as that of AB400H3PO4.
Biochar attracted more and more attention as a processing adsorbent of heavy metals in the field of environmental protection, due to its wide source of raw materials, abundant active functional groups in surface, and stable physical and chemical properties. In this work, pine sawdust was used to synthesize biochar at a carbonization temperature of 400 ℃(AB400) by using HNO3, H3PO4, NH3 · H2O, Ca (OH)2 as the modification agent of the biochar. SEM, FTIR, Boehm titration method and Zeta potential determination were adopted to characteriza Biochar AB400. And Cr(Ⅵ) adsorption experiment was conducted. After modification, the structure of biochar appeared semi-penetrating to penetrating round collapse with micropores. Under the conditions of acid modification, the content of intermediate acid functional groups of AB400HNO3 and AB400H3PO4 increased, and the pH values of biochar decreased, corresponding to the increase in pHpzc value. As for the Cr(Ⅵ) adsorption, the overall adsorption performance of the acid modified biochar was better than that of alkaline modified biochar, and AB400H3PO4 achieved the best adsorption performance with an adsorption capacity increased from 58.48 mg/g to 101.82 mg/g. This was probably because the surface of alkaline modified biochar was negatively charged and repulsive to the oxygen-containing anions of Cr(Ⅵ). AB400HNO3 had smaller volume of micropores and a smaller number of round collapses than AB400H3PO4. Although the surface of AB400HNO3 was also positively charged, its adsorption performance was not as good as that of AB400H3PO4.
2020, 38(6): 35-39,74.
doi: 10.13205/j.hjgc.202006006
Abstract:
In this study, Bufo Raddei was taken as the research object, and the polluted water wetland and the relatively pollution-free Yellow River Wetland Reserve on the south side of the tailing wetland in Baotou, were taken as the research sites. Through analysis of morphological indexes, testis organ coefficient, sperm dynamic parameters, sperm deformity rate, sex hormone, micro-nucleus rate, and DNA damage of different male B. raddei, the toxic effect of compound pollution of tailing wetland on male gonads of B. raddei was studied. The results showed that the condition factor (CF) and the testis organ coefficient of B. raddei in tailing wetland was significantly higher than that in Xiaobaihe wetland (P < 0.01). In addition, the whipping frequency of sperms in the tailing wetland was significantly improved, while the sperm motility was significantly decreased (P<0.05). The sperm deformity rate, erythrocyte micro-nucleus, and DNA damage were obviously higher than that in the Xiaobaihe wetland (P<0.05). The results showed that the compound pollution of tailing wetland resulted in decrease of the sperm quality and increase of the micro-nucleus rate and DNA damage, which influenced the toxicological effect of male gonads. The toxic stress of compound pollution was eased by increasing the condition factor and the coefficient of spermatozoa. The above results had positive effect on the population protection, and ecological balance maintenance of amphibians in the compound pollution site of heavy metals.
In this study, Bufo Raddei was taken as the research object, and the polluted water wetland and the relatively pollution-free Yellow River Wetland Reserve on the south side of the tailing wetland in Baotou, were taken as the research sites. Through analysis of morphological indexes, testis organ coefficient, sperm dynamic parameters, sperm deformity rate, sex hormone, micro-nucleus rate, and DNA damage of different male B. raddei, the toxic effect of compound pollution of tailing wetland on male gonads of B. raddei was studied. The results showed that the condition factor (CF) and the testis organ coefficient of B. raddei in tailing wetland was significantly higher than that in Xiaobaihe wetland (P < 0.01). In addition, the whipping frequency of sperms in the tailing wetland was significantly improved, while the sperm motility was significantly decreased (P<0.05). The sperm deformity rate, erythrocyte micro-nucleus, and DNA damage were obviously higher than that in the Xiaobaihe wetland (P<0.05). The results showed that the compound pollution of tailing wetland resulted in decrease of the sperm quality and increase of the micro-nucleus rate and DNA damage, which influenced the toxicological effect of male gonads. The toxic stress of compound pollution was eased by increasing the condition factor and the coefficient of spermatozoa. The above results had positive effect on the population protection, and ecological balance maintenance of amphibians in the compound pollution site of heavy metals.
2020, 38(6): 40-46.
doi: 10.13205/j.hjgc.202006007
Abstract:
The development of modern industry caused Cr(Ⅵ) soil pollution increasingly prominent. The researches on the prevention and control of soil pollution with Cr(Ⅵ) attracted more and more attention. This study selected the low-risk plot soil as the experiment material. Based on soil column leaching experiments, the migration and transformation of water-soluble Cr(Ⅵ) in the soil under the action of mixed Bacillus were investigated. The results showed that the water-soluble Cr(Ⅵ) migration in soil was motivated by the migration of water in soil. In the control group, the migration of water-soluble Cr(Ⅵ) in the soil showed a trend of decreasing concentration with increasing soil depth; in the mixed Bacillus treatment group, Bacillus hindered water-soluble Cr(Ⅵ) migration in the early stage(0~10 days), but had little effect in the middle and later stage(10~30 days). During the migration process, the effect of mixing Bacillus made soil water soluble Cr(Ⅵ) concentration reduced. For example, after 30 days of soil column leaching, the water-soluble Cr(Ⅵ) concentration of the 175-H soil column compared with the 175-D soil column at the depths of 5, 10, 15, 20 cm were decreased by 3.55, 2.03, 1.87, 1.31 mg/kg. At the same time, the leaching of Cr(Ⅵ)-containing solution increased the relative abundance of chromium-resistant bacteria in the soil, such as Bacillus.
The development of modern industry caused Cr(Ⅵ) soil pollution increasingly prominent. The researches on the prevention and control of soil pollution with Cr(Ⅵ) attracted more and more attention. This study selected the low-risk plot soil as the experiment material. Based on soil column leaching experiments, the migration and transformation of water-soluble Cr(Ⅵ) in the soil under the action of mixed Bacillus were investigated. The results showed that the water-soluble Cr(Ⅵ) migration in soil was motivated by the migration of water in soil. In the control group, the migration of water-soluble Cr(Ⅵ) in the soil showed a trend of decreasing concentration with increasing soil depth; in the mixed Bacillus treatment group, Bacillus hindered water-soluble Cr(Ⅵ) migration in the early stage(0~10 days), but had little effect in the middle and later stage(10~30 days). During the migration process, the effect of mixing Bacillus made soil water soluble Cr(Ⅵ) concentration reduced. For example, after 30 days of soil column leaching, the water-soluble Cr(Ⅵ) concentration of the 175-H soil column compared with the 175-D soil column at the depths of 5, 10, 15, 20 cm were decreased by 3.55, 2.03, 1.87, 1.31 mg/kg. At the same time, the leaching of Cr(Ⅵ)-containing solution increased the relative abundance of chromium-resistant bacteria in the soil, such as Bacillus.
2020, 38(6): 47-51.
doi: 10.13205/j.hjgc.202006008
Abstract:
This paper used two kinds of alkaline solution extraction/flame atomic absorption methods, Solid Waste-Determination of Hexavalent Chromium-by Alkaline Digestion/Flame Atomic Absorption Spectrophotometic (HJ 687—2014) and Soil and Sediment-Determination of Cr(Ⅵ)-Alkaline Digestion/Flame Atomic Absorption Spectrometry (HJ 1082—2019). The content of hexavalent chromium in solid waste and soil samples was measured and the experimental procedures, analytical method performance and uncertainty evaluation results of the two methods were compared and verified. The results showed that the detection limit of the HJ 687—2014 method was relatively higher, which was not suitable for the determination of soil with lower concentration. In HJ 1082—2019, it was required to configure the working curve according to the steps of sample preparation, which considered the influence of matrix interference. The detection limit of HJ 687—2014 was 0.28 mg/kg, the relative standard deviation was 0.69%~0.93%, and the sample recovery rate was 95.7%~97.2%. And the detection limit of HJ 1082—2019 was 0.17 mg/kg, the relative standard deviation was 0.6%~3.0%, and the sample recovery rate was 76.0%~83.1%. For the analysis of the same actual sample, the results of the two methods were similar. The detecting results of HJ 687—2014 and HJ 1082—2019 were (48.1±4.2), (46.6±5.4) mg/kg. After comparison, it was found that the main processes affecting the uncertainty of HJ 687—2014 and HJ 1082—2019 were curve fitting and sample digestion, respectively.
This paper used two kinds of alkaline solution extraction/flame atomic absorption methods, Solid Waste-Determination of Hexavalent Chromium-by Alkaline Digestion/Flame Atomic Absorption Spectrophotometic (HJ 687—2014) and Soil and Sediment-Determination of Cr(Ⅵ)-Alkaline Digestion/Flame Atomic Absorption Spectrometry (HJ 1082—2019). The content of hexavalent chromium in solid waste and soil samples was measured and the experimental procedures, analytical method performance and uncertainty evaluation results of the two methods were compared and verified. The results showed that the detection limit of the HJ 687—2014 method was relatively higher, which was not suitable for the determination of soil with lower concentration. In HJ 1082—2019, it was required to configure the working curve according to the steps of sample preparation, which considered the influence of matrix interference. The detection limit of HJ 687—2014 was 0.28 mg/kg, the relative standard deviation was 0.69%~0.93%, and the sample recovery rate was 95.7%~97.2%. And the detection limit of HJ 1082—2019 was 0.17 mg/kg, the relative standard deviation was 0.6%~3.0%, and the sample recovery rate was 76.0%~83.1%. For the analysis of the same actual sample, the results of the two methods were similar. The detecting results of HJ 687—2014 and HJ 1082—2019 were (48.1±4.2), (46.6±5.4) mg/kg. After comparison, it was found that the main processes affecting the uncertainty of HJ 687—2014 and HJ 1082—2019 were curve fitting and sample digestion, respectively.
2020, 38(6): 52-57.
doi: 10.13205/j.hjgc.202006009
Abstract:
In order to solve the problems of hexavalent chromium contaminated soil with a high proportion of acid-soluble, incomplete reduction and detoxification, and easy recovery in the later period, remediation idea of water-soluble hexavalent chromium rapid reduction and acid-soluble hexavalent chromium long-term reduction was determined. The experiments were designed to investigate the effect of adding pyrite alone to the treatment of hexavalent chromium, and explored the long-term stability of contaminated soil by step reduction of using ferrous sulfate and pyrite, and a 540-day long-term monitoring was carried out. The results showed:FeSO4·7H2O reducing agent was prone to oxidation in the natural environment and loosed its reducing power, leading to its poor long-term performance, and inability to fully reduce slow-release acid-soluble hexavalent chromium. It was necessary to add a long-acting reduction slow-release agent to continuously reduce acid-soluble hexavalent chromium. Pyrite alone could remediate water-soluble hexavalent chromium-contaminated soil, the leaching concentration of hexavalent chromium in soil decreased to 30.4 mg/L in the mixing of 20% pyrite, 14 days of reaction. Using ferrous sulfate and pyrite to reduce the hexavalent chromium contaminated soil mainly in acid soluble state: add 2% ferrous sulfate curing for 3 days and then add 3% pyrite for 27 days, the leaching concentration of hexavalent chromium droped to 0.29 mg/L; adding 5% pyrite, the leaching concentration of hexavalent chromium could be reduced to 0.43 mg/L after 4 days of reaction, after which the leaching concentration of hexavalent chromium remained stable. According to 540 days of long-term monitoring data, the leaching concentration did not rise.
In order to solve the problems of hexavalent chromium contaminated soil with a high proportion of acid-soluble, incomplete reduction and detoxification, and easy recovery in the later period, remediation idea of water-soluble hexavalent chromium rapid reduction and acid-soluble hexavalent chromium long-term reduction was determined. The experiments were designed to investigate the effect of adding pyrite alone to the treatment of hexavalent chromium, and explored the long-term stability of contaminated soil by step reduction of using ferrous sulfate and pyrite, and a 540-day long-term monitoring was carried out. The results showed:FeSO4·7H2O reducing agent was prone to oxidation in the natural environment and loosed its reducing power, leading to its poor long-term performance, and inability to fully reduce slow-release acid-soluble hexavalent chromium. It was necessary to add a long-acting reduction slow-release agent to continuously reduce acid-soluble hexavalent chromium. Pyrite alone could remediate water-soluble hexavalent chromium-contaminated soil, the leaching concentration of hexavalent chromium in soil decreased to 30.4 mg/L in the mixing of 20% pyrite, 14 days of reaction. Using ferrous sulfate and pyrite to reduce the hexavalent chromium contaminated soil mainly in acid soluble state: add 2% ferrous sulfate curing for 3 days and then add 3% pyrite for 27 days, the leaching concentration of hexavalent chromium droped to 0.29 mg/L; adding 5% pyrite, the leaching concentration of hexavalent chromium could be reduced to 0.43 mg/L after 4 days of reaction, after which the leaching concentration of hexavalent chromium remained stable. According to 540 days of long-term monitoring data, the leaching concentration did not rise.
2020, 38(6): 58-66.
doi: 10.13205/j.hjgc.202006010
Abstract:
In this study, a low-cost and highly efficient composite material (ZVI-SM) with nanoscale zero-valent iron loaded by biochar was synthesized and applied to the remediation of copper, cobalt, nickel and chromium contaminated soil. The effects of biochar precursors and biochar composites prepared at different carbonation temperatures on the remediation of heavy metal contamination, and their removal mechanisms were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and metal adsorption experiment. FeCr2O4 formed by adsorption and reduction greatly reduced the toxicity of chromium and improved the removal efficiency of copper, cobalt and nickel. The introduction of Fe0 not only increased the adsorption capacity of heavy metals to biochar, but also solved the problem of toxicity of Cr(Ⅵ). XPS further clarified that biochar could be used as the electron transfer medium; the strong interaction between the gain and loss electrons of the surface functional groups; Fe0 could enhance the removal effect of the composite material on multi-heavy metal ions; besides ZVI-SM500, the removal rates of rest of the four materials, ZVI-SM100, 300, 400, 700 for copper, cobalt, nickel, chromium were much higher than the commercial nanoscale Fe0 and single application of biological carbon materials; this kind of composite material (ZVI-SM) showed a strong affinity and reactivity to chromium and copper, and completely removed copper and chromium in 5 minutes. Cobalt and nickel could also achieve more than 80% removal rate in 180 minutes. There was a significant ion competition effect in the reaction process in the order of Cr≥Cu>Co>Ni, consistent with the trend of the standard reduction potential of metal ions. Soil remediation experiments showed that ZNI-SM300 for remediation of contaminated soil, after 15 days, the content of Cr(Ⅵ) decreased from 480 mg/kg to 0.52 mg/kg, and the total amount of water-soluble Cr decreased from 500 mg/kg to 1.2 mg/kg. The immobilization efficiency of both was more than 99%, while the total removal effect of water-soluble copper, cobalt, nickel and Cr(Ⅵ) was achieved. Therefore, the nanoscale zero-valent iron with SM300 as the carrier could be used as the ideal material for the remediation of soil contaminated by composite heavy metals.
In this study, a low-cost and highly efficient composite material (ZVI-SM) with nanoscale zero-valent iron loaded by biochar was synthesized and applied to the remediation of copper, cobalt, nickel and chromium contaminated soil. The effects of biochar precursors and biochar composites prepared at different carbonation temperatures on the remediation of heavy metal contamination, and their removal mechanisms were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and metal adsorption experiment. FeCr2O4 formed by adsorption and reduction greatly reduced the toxicity of chromium and improved the removal efficiency of copper, cobalt and nickel. The introduction of Fe0 not only increased the adsorption capacity of heavy metals to biochar, but also solved the problem of toxicity of Cr(Ⅵ). XPS further clarified that biochar could be used as the electron transfer medium; the strong interaction between the gain and loss electrons of the surface functional groups; Fe0 could enhance the removal effect of the composite material on multi-heavy metal ions; besides ZVI-SM500, the removal rates of rest of the four materials, ZVI-SM100, 300, 400, 700 for copper, cobalt, nickel, chromium were much higher than the commercial nanoscale Fe0 and single application of biological carbon materials; this kind of composite material (ZVI-SM) showed a strong affinity and reactivity to chromium and copper, and completely removed copper and chromium in 5 minutes. Cobalt and nickel could also achieve more than 80% removal rate in 180 minutes. There was a significant ion competition effect in the reaction process in the order of Cr≥Cu>Co>Ni, consistent with the trend of the standard reduction potential of metal ions. Soil remediation experiments showed that ZNI-SM300 for remediation of contaminated soil, after 15 days, the content of Cr(Ⅵ) decreased from 480 mg/kg to 0.52 mg/kg, and the total amount of water-soluble Cr decreased from 500 mg/kg to 1.2 mg/kg. The immobilization efficiency of both was more than 99%, while the total removal effect of water-soluble copper, cobalt, nickel and Cr(Ⅵ) was achieved. Therefore, the nanoscale zero-valent iron with SM300 as the carrier could be used as the ideal material for the remediation of soil contaminated by composite heavy metals.
2020, 38(6): 67-74.
doi: 10.13205/j.hjgc.202006011
Abstract:
Aiming at the treatment of Cr(Ⅵ) pollution in chromite ore processing residue (COPR), a wet detoxification process of COPR with sulfuric acid leaching and ferrous sulfate reduction was proposed in this paper. Based on the characterization of the surface morphologies of COPR before and after remediation, the treatment effect and remediation mechanism of Cr(Ⅵ) under different treatment conditions were investigated. The results showed that when the wet ball milling time of COPR was 20 min, 98.68% of the chromium slag particles passed through a 200 mesh sieve, and the leaching rate of water soluble Cr(Ⅵ) reached 40.96%. When the slag sulfuric acid was added at 60%, the liquid-solid ratio was 4∶1, and the acid dissolution time was 2.5 h, the leaching of Cr(Ⅵ) tended to be saturated. At this time, the pH of endpoint was 5.8, and the total leaching rate of Cr(Ⅵ) was 95.38%. When the ferrous sulfate was added at 40%, the content of Cr(Ⅵ) decreased to 1.38 mg/kg. The removal of Cr (Ⅵ) in COPR was mainly related to the dissolution of Cr(Ⅵ)-containing minerals by sulfuric acid, the ion exchange of SO42- and CrO42-, and the reduction of Cr(Ⅵ) in solution by Fe(Ⅱ).
Aiming at the treatment of Cr(Ⅵ) pollution in chromite ore processing residue (COPR), a wet detoxification process of COPR with sulfuric acid leaching and ferrous sulfate reduction was proposed in this paper. Based on the characterization of the surface morphologies of COPR before and after remediation, the treatment effect and remediation mechanism of Cr(Ⅵ) under different treatment conditions were investigated. The results showed that when the wet ball milling time of COPR was 20 min, 98.68% of the chromium slag particles passed through a 200 mesh sieve, and the leaching rate of water soluble Cr(Ⅵ) reached 40.96%. When the slag sulfuric acid was added at 60%, the liquid-solid ratio was 4∶1, and the acid dissolution time was 2.5 h, the leaching of Cr(Ⅵ) tended to be saturated. At this time, the pH of endpoint was 5.8, and the total leaching rate of Cr(Ⅵ) was 95.38%. When the ferrous sulfate was added at 40%, the content of Cr(Ⅵ) decreased to 1.38 mg/kg. The removal of Cr (Ⅵ) in COPR was mainly related to the dissolution of Cr(Ⅵ)-containing minerals by sulfuric acid, the ion exchange of SO42- and CrO42-, and the reduction of Cr(Ⅵ) in solution by Fe(Ⅱ).
2020, 38(6): 75-80.
doi: 10.13205/j.hjgc.202006012
Abstract:
The electroplating wastewater generated during the electroplating process of the machinery factory will cause soil hexavalent chromium and cyanide pollution. Relying on the long-term use of the electroplating process of contaminated site remediation projects, the remediation target and the amount of work were determined through the preliminary site environmental investigation and risk assessment results, and the site soil pollution degree and pollution scope analysis; synthesis of site features and pollution characteristics, conduction of remediation technology screening determined that chemical oxidation, chemical reduction and solidification or stabilization was the core remediation technology for the project. The optimal composition and appending proportion of repairing agents were obtained by conducting small-scale and pilot-scale experiments, and used to implement the project. The results showed that after the chemical oxidation, chemical reduction and solidification or stabilization processing procedure of the hexavalent chromium and cyanide compound contaminated soil, the maximum exceeded concentration was reduced from the original 37.3, 186.0 mg/kg to below the corresponding standard limits of 3.0, 22 mg/kg, respectively; the leaching concentration of hexavalent chromium was lower than 0.5 mg/L, meeting the remediation requirements. The successful practice of the remediation project could provide reference for the design and implementation of remediation projects of other compound contaminated sites.
The electroplating wastewater generated during the electroplating process of the machinery factory will cause soil hexavalent chromium and cyanide pollution. Relying on the long-term use of the electroplating process of contaminated site remediation projects, the remediation target and the amount of work were determined through the preliminary site environmental investigation and risk assessment results, and the site soil pollution degree and pollution scope analysis; synthesis of site features and pollution characteristics, conduction of remediation technology screening determined that chemical oxidation, chemical reduction and solidification or stabilization was the core remediation technology for the project. The optimal composition and appending proportion of repairing agents were obtained by conducting small-scale and pilot-scale experiments, and used to implement the project. The results showed that after the chemical oxidation, chemical reduction and solidification or stabilization processing procedure of the hexavalent chromium and cyanide compound contaminated soil, the maximum exceeded concentration was reduced from the original 37.3, 186.0 mg/kg to below the corresponding standard limits of 3.0, 22 mg/kg, respectively; the leaching concentration of hexavalent chromium was lower than 0.5 mg/L, meeting the remediation requirements. The successful practice of the remediation project could provide reference for the design and implementation of remediation projects of other compound contaminated sites.
2020, 38(6): 81-87,114.
doi: 10.13205/j.hjgc.202006013
Abstract:
The design scale of the upgrading project of the fourth-stage leachate treatment plant of Shanghai Laogang Landfill is 3200 m3/d. The effluent from negative pressure steam-stripping pretreatment and MBR biological treatment adopted the advanced treatment technology of nanofiltration & three-levels reduction of nanofiltration concentrate, with an excellent recovery rate of clear water. The actual engineering operation showed that the effluent concentrations of COD, NH3-N and TN met the standard of Table 2 in GB 16889—2008 after the advanced treatment, on the premise of the influent concentrations of COD, NH3-N and NOx--N were lower than 800, 5, 15 mg/L, respectively. Meanwhile, clear water recovery rate of the system could reach 97%.
The design scale of the upgrading project of the fourth-stage leachate treatment plant of Shanghai Laogang Landfill is 3200 m3/d. The effluent from negative pressure steam-stripping pretreatment and MBR biological treatment adopted the advanced treatment technology of nanofiltration & three-levels reduction of nanofiltration concentrate, with an excellent recovery rate of clear water. The actual engineering operation showed that the effluent concentrations of COD, NH3-N and TN met the standard of Table 2 in GB 16889—2008 after the advanced treatment, on the premise of the influent concentrations of COD, NH3-N and NOx--N were lower than 800, 5, 15 mg/L, respectively. Meanwhile, clear water recovery rate of the system could reach 97%.
2020, 38(6): 88-93.
doi: 10.13205/j.hjgc.202006014
Abstract:
The content of lead in groundwater of Lhasa landfill was increased with the improvement of its service life. In order to protect groundwater, physical shielding method, extraction treatment method and in-situ remediation method were used as the candidate remediation schemes. The AHP-TOPSIS method was used to select the best restoration scheme. Firstly, the weights for all factors were determined by analytic hierarchy process (AHP). The AHP model was established by selecting six indexes systems: construction conditions, economic conditions, technical conditions, environmental conditions, pollutant characteristics and hydrochemical characteristics. Then, the ranking method of TOPSIS close to the ideal goal was used to analyze the selection of final repair schemes. The results showed that the weight values obtained by the two methods were in the order of in-situ remediation, physical shielding and extraction. Finally, it was determined that in-situ remediation technology was the most suitable scheme for groundwater remediation in the site.
The content of lead in groundwater of Lhasa landfill was increased with the improvement of its service life. In order to protect groundwater, physical shielding method, extraction treatment method and in-situ remediation method were used as the candidate remediation schemes. The AHP-TOPSIS method was used to select the best restoration scheme. Firstly, the weights for all factors were determined by analytic hierarchy process (AHP). The AHP model was established by selecting six indexes systems: construction conditions, economic conditions, technical conditions, environmental conditions, pollutant characteristics and hydrochemical characteristics. Then, the ranking method of TOPSIS close to the ideal goal was used to analyze the selection of final repair schemes. The results showed that the weight values obtained by the two methods were in the order of in-situ remediation, physical shielding and extraction. Finally, it was determined that in-situ remediation technology was the most suitable scheme for groundwater remediation in the site.
2020, 38(6): 94-101.
doi: 10.13205/j.hjgc.202006015
Abstract:
The large amount of phosphorus in the water led to eutrophication, deterioration of water quality and thus made black and odorous water. In order to treat phosphorus mainly including phosphate and phytic acid in water, Mg-laden biochar was prepared with bamboo and magnesium chloride by nitrogen pyrolysis to adsorb inorganic phosphorus and organic phosphorus in water, and at the same time, realized resource utilization of biochar. In this paper, the kinetics and adsorption equilibrium as well as desorption of phosphate and phytic acid adsorbed on Mg-laden biochar in water were studied. The adsorption mechanism of phosphate and phytic acid on Mg-laden biochar was analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The results showed that the adsorption of phosphate and phytic acid on Mg-laden biochar was significantly increased, compared to biochar; and the adsorption equilibrium concentrations of phosphate and phytic acid were 105, 165 mg/g, respectively. Both phosphate and phytic acid kinetic results complied well with the pseudo-second-order. Both Langmuir and Freundlich model produced the adsorption isotherm data well. The maximum adsorption of phytic acid was much higher than that of phosphate and the adsorption process was controlled by multiple mechanisms, dominated by chemical precipitation adsorption. Characterization results from XRD, SEM and FTIR showed that Mg-laden biochar formed needle-like magnesium phosphate hydrate with phosphate, and amorphous magnesium-phosphorus complex with phytic acid.
The large amount of phosphorus in the water led to eutrophication, deterioration of water quality and thus made black and odorous water. In order to treat phosphorus mainly including phosphate and phytic acid in water, Mg-laden biochar was prepared with bamboo and magnesium chloride by nitrogen pyrolysis to adsorb inorganic phosphorus and organic phosphorus in water, and at the same time, realized resource utilization of biochar. In this paper, the kinetics and adsorption equilibrium as well as desorption of phosphate and phytic acid adsorbed on Mg-laden biochar in water were studied. The adsorption mechanism of phosphate and phytic acid on Mg-laden biochar was analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The results showed that the adsorption of phosphate and phytic acid on Mg-laden biochar was significantly increased, compared to biochar; and the adsorption equilibrium concentrations of phosphate and phytic acid were 105, 165 mg/g, respectively. Both phosphate and phytic acid kinetic results complied well with the pseudo-second-order. Both Langmuir and Freundlich model produced the adsorption isotherm data well. The maximum adsorption of phytic acid was much higher than that of phosphate and the adsorption process was controlled by multiple mechanisms, dominated by chemical precipitation adsorption. Characterization results from XRD, SEM and FTIR showed that Mg-laden biochar formed needle-like magnesium phosphate hydrate with phosphate, and amorphous magnesium-phosphorus complex with phytic acid.
2020, 38(6): 102-107.
doi: 10.13205/j.hjgc.202006016
Abstract:
In this paper, with the conventional pollutants addition, adsorption was found out as the main removal pathway of oxytetracycline, ciprofloxacin and sulfamethazine in the constructed wetland, and its contribution rates of that were 75%, 85% and 62%, respectively. Hydrolysis was the secondary removal pathway of oxytetracycline and ciprofloxacin (21% and 19%), and biodegradation was the secondary removal pathway of sulfamethazine (23%). Compared to the treatment group without conventional pollutants addition, the effect of conventional pollutants on antibiotics adsorption was not significant, yet that could inhibit hydrolysis process of oxytetracycline and ciprofloxacin (about 7% and 5%), and conventional pollutants could enhance contribution of biodegradation for sulfamethazine (about 21%).
In this paper, with the conventional pollutants addition, adsorption was found out as the main removal pathway of oxytetracycline, ciprofloxacin and sulfamethazine in the constructed wetland, and its contribution rates of that were 75%, 85% and 62%, respectively. Hydrolysis was the secondary removal pathway of oxytetracycline and ciprofloxacin (21% and 19%), and biodegradation was the secondary removal pathway of sulfamethazine (23%). Compared to the treatment group without conventional pollutants addition, the effect of conventional pollutants on antibiotics adsorption was not significant, yet that could inhibit hydrolysis process of oxytetracycline and ciprofloxacin (about 7% and 5%), and conventional pollutants could enhance contribution of biodegradation for sulfamethazine (about 21%).
2020, 38(6): 108-114.
doi: 10.13205/j.hjgc.202006017
Abstract:
The water-sediment-Hydrilla verticillata system was simulated with several measures such as controlling temperature and light in the walk-in simulation laboratory. The control group and the 30g, 60g Hydrilla verticillata group were naturally decomposed, the variation of Hydrilla biomass and total phosphorus and various forms of phosphorus in the water were detected during the decay of Hydrilla verticillata, to discusss the transportation and transformation of phosphorus within the system. The results showed that the decomposition of Hydrilla verticillata had obvious stages, and the decomposition rate in the early stage of the experiment was significantly higher than that in the middle and late stage. During the experiment, the trend of DO change in the Hydrilla verticillata groups was first decreased and then increased with consistency, and the change interval of pH value was between 7.4 and 8.4, with little surges. In the control group and the 30 g Hydrilla verticillata group, the ORP showed a trend of increasing first and then decreasing. The ORP of the 60g kelp group decreased first and then increased. During the whole research period, the phosphorus contents of the groups were in the order of 60 g Hydrilla verticillata > 30 g > the control group. The decomposing of Hydrilla verticilla changed the circulation of phosphorus in the system, inhibited the release of phosphorus in the sediment in the early stage of decomposing, promoted the release of phosphorus in the late stage of decomposing, and had a significant effect on the migration and transformation of various forms of phosphorus.
The water-sediment-Hydrilla verticillata system was simulated with several measures such as controlling temperature and light in the walk-in simulation laboratory. The control group and the 30g, 60g Hydrilla verticillata group were naturally decomposed, the variation of Hydrilla biomass and total phosphorus and various forms of phosphorus in the water were detected during the decay of Hydrilla verticillata, to discusss the transportation and transformation of phosphorus within the system. The results showed that the decomposition of Hydrilla verticillata had obvious stages, and the decomposition rate in the early stage of the experiment was significantly higher than that in the middle and late stage. During the experiment, the trend of DO change in the Hydrilla verticillata groups was first decreased and then increased with consistency, and the change interval of pH value was between 7.4 and 8.4, with little surges. In the control group and the 30 g Hydrilla verticillata group, the ORP showed a trend of increasing first and then decreasing. The ORP of the 60g kelp group decreased first and then increased. During the whole research period, the phosphorus contents of the groups were in the order of 60 g Hydrilla verticillata > 30 g > the control group. The decomposing of Hydrilla verticilla changed the circulation of phosphorus in the system, inhibited the release of phosphorus in the sediment in the early stage of decomposing, promoted the release of phosphorus in the late stage of decomposing, and had a significant effect on the migration and transformation of various forms of phosphorus.
2020, 38(6): 115-120.
doi: 10.13205/j.hjgc.202006018
Abstract:
Treatment of high concentration sulfide wastewater by oxidation with Na2SO3 was investigated under the condition of atmospheric pressure and room temperature. The effects of initial pH, Na2SO3 dosage on the sulfide removal efficiency and production of oxidation products were studied. The crystal structure of solid phase was analyzed. At the same time, a method combining theoretical calculation of electrode potential of sulfite oxidative desulfurization and separation of target product S0 by reaction-centrifugation coupling was used to study the sulfide oxidation process. The results indicated that under the optimal condition of initial pH 5 and Na2SO3 dosage of 5 g/L, after reaction 15 min, the sulfide removal rate could reached 71.79% and the formation of sulfur could reached 603.5 mg/L. Using the method of separated target product S0 by reaction-centrifugation coupling under the condition of 2500 r/min rotating speed, could increase the formation of S0 to 819.5 mg/L. The result of X-Ray Diffraction indicated that the solid phase products of flocculation system and ordinary system were constitutionally stable annular rhombic sulfur (α-sulfur) at room temperature.
Treatment of high concentration sulfide wastewater by oxidation with Na2SO3 was investigated under the condition of atmospheric pressure and room temperature. The effects of initial pH, Na2SO3 dosage on the sulfide removal efficiency and production of oxidation products were studied. The crystal structure of solid phase was analyzed. At the same time, a method combining theoretical calculation of electrode potential of sulfite oxidative desulfurization and separation of target product S0 by reaction-centrifugation coupling was used to study the sulfide oxidation process. The results indicated that under the optimal condition of initial pH 5 and Na2SO3 dosage of 5 g/L, after reaction 15 min, the sulfide removal rate could reached 71.79% and the formation of sulfur could reached 603.5 mg/L. Using the method of separated target product S0 by reaction-centrifugation coupling under the condition of 2500 r/min rotating speed, could increase the formation of S0 to 819.5 mg/L. The result of X-Ray Diffraction indicated that the solid phase products of flocculation system and ordinary system were constitutionally stable annular rhombic sulfur (α-sulfur) at room temperature.
2020, 38(6): 121-125.
doi: 10.13205/j.hjgc.202006019
Abstract:
In order to study the nitrogen fixation of the water in North Taihu Lake and the influencing factors, with the acetylene reduction technique(ART),the nitrogen fixation rate in situ of the water column and the roles of nitrogen (N), iron (Fe) and molybdenum(Mo)in controlling nitrogen fixation rate of Anabaena spp indoor were studied. The results showed that the annual mean nitrogen fixation rate of North Taihu Lake was 3.08 ng/(L·h), with a obvious spatio-temporal variation. The highest rate appeared in Meiliang Bay (2.75 ng/(L·h)) and the lowest rate appeared in the Center of lake (1.38 ng/(L·h)) in space. The rate in summer (6.03 ng/(L·h)) was the highest, and then spring (1.08 ng/(L·h)) and autumn (0.81 ng/(L·h)),lowest in winter (6.97×10-5 ng/(L·h)). With the correlation analysis,the growth of Anabeana spp was not effected by nitrogen, iron and molybdenum (P>0.05). The nitrogen fixation rates were effected by nitrogen (P<0.01), other than iron and molybdenum (P>0.05). Temperature,DTN,the biomass of algae (P<0.01) and NO3- (P<0.05) of water in situ were the main influencing factors of the spatio-temporal variation in the in situ nitrogen fixation rates.
In order to study the nitrogen fixation of the water in North Taihu Lake and the influencing factors, with the acetylene reduction technique(ART),the nitrogen fixation rate in situ of the water column and the roles of nitrogen (N), iron (Fe) and molybdenum(Mo)in controlling nitrogen fixation rate of Anabaena spp indoor were studied. The results showed that the annual mean nitrogen fixation rate of North Taihu Lake was 3.08 ng/(L·h), with a obvious spatio-temporal variation. The highest rate appeared in Meiliang Bay (2.75 ng/(L·h)) and the lowest rate appeared in the Center of lake (1.38 ng/(L·h)) in space. The rate in summer (6.03 ng/(L·h)) was the highest, and then spring (1.08 ng/(L·h)) and autumn (0.81 ng/(L·h)),lowest in winter (6.97×10-5 ng/(L·h)). With the correlation analysis,the growth of Anabeana spp was not effected by nitrogen, iron and molybdenum (P>0.05). The nitrogen fixation rates were effected by nitrogen (P<0.01), other than iron and molybdenum (P>0.05). Temperature,DTN,the biomass of algae (P<0.01) and NO3- (P<0.05) of water in situ were the main influencing factors of the spatio-temporal variation in the in situ nitrogen fixation rates.
2020, 38(6): 126-131,107.
doi: 10.13205/j.hjgc.202006020
Abstract:
This study carried out a laboratory column experiment to simulate the infiltration process, analyzed the variation of total dissolved organic matter (DOM) content and structural composition, and extracted the main organic components with the recommended method by IHSS for analysis and characterization. The results showed that after infiltration, the COD concentration in reclaimed water decreased from 57.90 mg/L (0 h) to 21.50 mg/L (159 h), and the removal efficiency reached 63%. Accordingly, the DOC concentration decreased from 12.40 mg/L to 7.16 mg/L, and the removal rate was 42%. Fluorescene regional integration results showed that aromatic protein-like substances and SMP-like substances were main components of DOM in reclaimed water; DOM in soil was mainly composed of humic acid (HA). Affected by the DOM leaching release in soil, the DOM of leachate from the experiment was mainly composed of HA (the proportion was more than 60%). The results of SEM and EDS analysis showed that the surface of HA was spongy, mainly composed of C (64.40%) and O (34.25%) elements. FTIR spectrum revealed that HA contained various functional groups such as hydroxyl and carboxyl groups. UV-Vis spectrum was monotonous and showed no characteristic. The ratios between characteristic peaks showed that the HA belonged to the macromolecular category.
This study carried out a laboratory column experiment to simulate the infiltration process, analyzed the variation of total dissolved organic matter (DOM) content and structural composition, and extracted the main organic components with the recommended method by IHSS for analysis and characterization. The results showed that after infiltration, the COD concentration in reclaimed water decreased from 57.90 mg/L (0 h) to 21.50 mg/L (159 h), and the removal efficiency reached 63%. Accordingly, the DOC concentration decreased from 12.40 mg/L to 7.16 mg/L, and the removal rate was 42%. Fluorescene regional integration results showed that aromatic protein-like substances and SMP-like substances were main components of DOM in reclaimed water; DOM in soil was mainly composed of humic acid (HA). Affected by the DOM leaching release in soil, the DOM of leachate from the experiment was mainly composed of HA (the proportion was more than 60%). The results of SEM and EDS analysis showed that the surface of HA was spongy, mainly composed of C (64.40%) and O (34.25%) elements. FTIR spectrum revealed that HA contained various functional groups such as hydroxyl and carboxyl groups. UV-Vis spectrum was monotonous and showed no characteristic. The ratios between characteristic peaks showed that the HA belonged to the macromolecular category.
2020, 38(6): 132-136,201.
doi: 10.13205/j.hjgc.202006021
Abstract:
The recovery strategy of sequential biocatalyst addition and the key points during the implementation of bio-augmentation strategy was investigated to rapid recovery of full-scale nitrification system with long-term inhibition in this study, which was difficult to recover through conventional regulations. The concentrations of ammonia, nitrate, nitrous, COD, alkalinity and total phenol were determined after adding high-efficient nitrifying bacteria in the lab-scale and full-scale experiments. Meanwhile, microscopic examination was carried out to analyze the changes of protometazoan animals. The results shown that ammonia concentration decreased significantly and the proto-metazoan animals appeared gradually after adding nitrifying bacteria. For the treatment of real coal chemical wastewater, the full-scale nitrification system can be realized long-term stable operation with the influent total phenol concentration lower than 10 mg/L. According to results, lab-scale experiment can be used as a preliminary reference for the feasibility of the bio-augmentation strategy. Accurate identification of the instability reasons or the inhibitors in full-scale nitrification system was the key point for the rapid recovery of the full-scale nitrification system. Through maximum extent to reduce inhibitor concentration, the nitrification reaction can be established quickly, and then the full-scale nitrification system also realized by using the recovery strategy of sequential biocatalyst addition basis on the conventional regulations.
The recovery strategy of sequential biocatalyst addition and the key points during the implementation of bio-augmentation strategy was investigated to rapid recovery of full-scale nitrification system with long-term inhibition in this study, which was difficult to recover through conventional regulations. The concentrations of ammonia, nitrate, nitrous, COD, alkalinity and total phenol were determined after adding high-efficient nitrifying bacteria in the lab-scale and full-scale experiments. Meanwhile, microscopic examination was carried out to analyze the changes of protometazoan animals. The results shown that ammonia concentration decreased significantly and the proto-metazoan animals appeared gradually after adding nitrifying bacteria. For the treatment of real coal chemical wastewater, the full-scale nitrification system can be realized long-term stable operation with the influent total phenol concentration lower than 10 mg/L. According to results, lab-scale experiment can be used as a preliminary reference for the feasibility of the bio-augmentation strategy. Accurate identification of the instability reasons or the inhibitors in full-scale nitrification system was the key point for the rapid recovery of the full-scale nitrification system. Through maximum extent to reduce inhibitor concentration, the nitrification reaction can be established quickly, and then the full-scale nitrification system also realized by using the recovery strategy of sequential biocatalyst addition basis on the conventional regulations.
2020, 38(6): 137-142,80.
doi: 10.13205/j.hjgc.202006022
Abstract:
In order to study the application effect of the blocking wall in a groundwater contaminated site, a city landfill in Sichuan province was taken an example and cadmium was selected as the target pollutant. The structure, location and scale of the blocking wall under specific conditions were designed through investigating hydrogeological conditions. The service life of the blocking wall was calculated by analytic method. MODFLOW and MT3D modules were used to simulate the distribution of cadmium pollution plume in groundwater before and after the blocking wall was set up, and the barrier effect was analyzed. The results showed that the blocking wall was a vertical barrier with funnel gate. The service life of the blocking wall was 12.51 years, under the condition that the thickness was set as 1 meter and Class Ⅲ groundwater quality standard was selected as the breakdown standard. In the contaminated field, cadmium would be absorbed by the blocking wall, and the hydraulic connection between the blocking wall and the downstream would be weakened, thus cadmium could be effectively blocked in groundwater.
In order to study the application effect of the blocking wall in a groundwater contaminated site, a city landfill in Sichuan province was taken an example and cadmium was selected as the target pollutant. The structure, location and scale of the blocking wall under specific conditions were designed through investigating hydrogeological conditions. The service life of the blocking wall was calculated by analytic method. MODFLOW and MT3D modules were used to simulate the distribution of cadmium pollution plume in groundwater before and after the blocking wall was set up, and the barrier effect was analyzed. The results showed that the blocking wall was a vertical barrier with funnel gate. The service life of the blocking wall was 12.51 years, under the condition that the thickness was set as 1 meter and Class Ⅲ groundwater quality standard was selected as the breakdown standard. In the contaminated field, cadmium would be absorbed by the blocking wall, and the hydraulic connection between the blocking wall and the downstream would be weakened, thus cadmium could be effectively blocked in groundwater.
2020, 38(6): 143-148,207.
doi: 10.13205/j.hjgc.202006023
Abstract:
With the rapid development of sponge city, permeable brick pavement has been widely used in practical engineering, but its impact on stormwater runoff thermal pollution is in shortage of systematic research. The artificial simulated rainfall method was used to study the stormwater runoff temperature reduction effect of the permeable brick paving system by using the impervious asphalt pavement as comparison. The research content include the runoff temperature of the permeable brick paving surface, the temperature of the permeate water, and the thermal transfer characteristics of each structural layer. The experimental results show that when P=5 a and the initial temperature of the permeable brick paving surface is 35, 42, 47 ℃, compared with impervious asphalt, the runoff temperature of the permeable brick paving surface can be reduced by 1.4~1.8 ℃, and the higher the initial temperature of the paving surface, the higher the temperature of the stormwater runoff, and the higher the temperature of the permeate water. The permeable brick paving structure layer can reduce the temperature of the permeable part of the stormwater runoff. The permeate water temperature is reduced by 3.5~4.9 ℃ compare to the runoff temperature. The rainfall return period has a significant effect on the runoff temperature, but its effect on the temperature of the permeate water is slight. Therefore, permeable brick paving can reduce urban stormwater runoff thermal pollution effectively.
With the rapid development of sponge city, permeable brick pavement has been widely used in practical engineering, but its impact on stormwater runoff thermal pollution is in shortage of systematic research. The artificial simulated rainfall method was used to study the stormwater runoff temperature reduction effect of the permeable brick paving system by using the impervious asphalt pavement as comparison. The research content include the runoff temperature of the permeable brick paving surface, the temperature of the permeate water, and the thermal transfer characteristics of each structural layer. The experimental results show that when P=5 a and the initial temperature of the permeable brick paving surface is 35, 42, 47 ℃, compared with impervious asphalt, the runoff temperature of the permeable brick paving surface can be reduced by 1.4~1.8 ℃, and the higher the initial temperature of the paving surface, the higher the temperature of the stormwater runoff, and the higher the temperature of the permeate water. The permeable brick paving structure layer can reduce the temperature of the permeable part of the stormwater runoff. The permeate water temperature is reduced by 3.5~4.9 ℃ compare to the runoff temperature. The rainfall return period has a significant effect on the runoff temperature, but its effect on the temperature of the permeate water is slight. Therefore, permeable brick paving can reduce urban stormwater runoff thermal pollution effectively.
2020, 38(6): 149-153,220.
doi: 10.13205/j.hjgc.202006024
Abstract:
With the widespread application of bioretention in the construction of sponge city in China, the optimal design of bioretention was paid more and more attention. However, due to the absence of systematically research on hydraulic characteristics analysis and design methods, the design method of urban road grate inlet was often directly adopt in overflow outlet design in the bioretention. However, there was a great difference between the hydraulic characteristics of overflow outlet in bioretention and traditional grate inlet on the road. For the above problems, the hydraulic characteristics of the overflow outlet in the bioretention was analyzed via theoretical methods, and the drainage capacity of which was discussed. The design method of overflow outlet in bioretention was analyzed with an example, so as to provide references for the optimal design of the bioretention overflow outlet.
With the widespread application of bioretention in the construction of sponge city in China, the optimal design of bioretention was paid more and more attention. However, due to the absence of systematically research on hydraulic characteristics analysis and design methods, the design method of urban road grate inlet was often directly adopt in overflow outlet design in the bioretention. However, there was a great difference between the hydraulic characteristics of overflow outlet in bioretention and traditional grate inlet on the road. For the above problems, the hydraulic characteristics of the overflow outlet in the bioretention was analyzed via theoretical methods, and the drainage capacity of which was discussed. The design method of overflow outlet in bioretention was analyzed with an example, so as to provide references for the optimal design of the bioretention overflow outlet.
2020, 38(6): 166-169,227.
doi: 10.13205/j.hjgc.202006027
Abstract:
The overflow port is an important part of the runoff control facility, but the hydraulic characteristics of the overflow port are currently in shortage of specific research. The design formula of the overflow port in the stormwater management manual at home and abroad was incomplete, which was not sufficient to guide the design calculation. As a representative of the overflow port, the thin-annular weir could also be considered as a macroscopic expression of the 'confluence’. Its height and inner diameter were two geometric elements that characterize the flow-head relationship. The flow-head relationship in different heights and inner diameters was measured by laboratory tests. The results showed that the height of the weir had a certain influence on the overcurrent capability of the thin-annular weir. The dimensionless curve was drawn for the annular thin-walled concrete with different inner diameters, and the general formula was obtained. This research could provide reference for the design calculation of the overflow port in sponge city facilities.
The overflow port is an important part of the runoff control facility, but the hydraulic characteristics of the overflow port are currently in shortage of specific research. The design formula of the overflow port in the stormwater management manual at home and abroad was incomplete, which was not sufficient to guide the design calculation. As a representative of the overflow port, the thin-annular weir could also be considered as a macroscopic expression of the 'confluence’. Its height and inner diameter were two geometric elements that characterize the flow-head relationship. The flow-head relationship in different heights and inner diameters was measured by laboratory tests. The results showed that the height of the weir had a certain influence on the overcurrent capability of the thin-annular weir. The dimensionless curve was drawn for the annular thin-walled concrete with different inner diameters, and the general formula was obtained. This research could provide reference for the design calculation of the overflow port in sponge city facilities.
2020, 38(6): 170-175,251.
doi: 10.13205/j.hjgc.202006028
Abstract:
In view of the problems of improper plant selection, poor landscape effect and high maintenance cost exposed in the process of green stormwater infrastructure construction, the evaluation and selection method of qualitative and quantitative were put forward. Taking herbaceous plants in Beijing as an example, a comprehensive plant evaluation system was established from four aspects of functional attribute, visual attribute, conservation management attribute and economic attribute. Thirty kinds of high-frequency herbaceous plants were graded and screened out for plant materials suitable for facility functions. The application prospect and design methods of meadow plant landscape in green stormwater infrastructure were discussed, which provided new ideas for the construction of green stormwater infrastructure with high efficiency and low cost.
In view of the problems of improper plant selection, poor landscape effect and high maintenance cost exposed in the process of green stormwater infrastructure construction, the evaluation and selection method of qualitative and quantitative were put forward. Taking herbaceous plants in Beijing as an example, a comprehensive plant evaluation system was established from four aspects of functional attribute, visual attribute, conservation management attribute and economic attribute. Thirty kinds of high-frequency herbaceous plants were graded and screened out for plant materials suitable for facility functions. The application prospect and design methods of meadow plant landscape in green stormwater infrastructure were discussed, which provided new ideas for the construction of green stormwater infrastructure with high efficiency and low cost.
2020, 38(6): 176-180,66.
doi: 10.13205/j.hjgc.202006029
Abstract:
The prediction of PM2.5 can effectively prevent people from the harm by heavy pollution. However, the existing methods often emphasize the influence of local historical information and neglect the effect of spatial transport. In this paper, we proposed a method, called as long-short-term memory-convolutional neural network (LSTM-CNN), to predict PM2.5 concentration of a specific air quality monitoring station over 6 h using historical PM2.5 concentration data, historical weather data, and time stamp data. The model consisted of two parts: 1) using long-short-term memory networks to model the local variation of PM2.5 concentrations caused by local factors; 2) using one-dimensional convolutional neural networks to model the variation of PM2.5 concentrations caused by spatial transport. We randomly selected 7 monitoring stations in urban and rural areas in Beijing from May 1st 2014 to April 30th 2015 to conduct the evaluation of LSTM-CNN model. The results showed that the proposed LSTM-CNN model could provide a better prediction result than LSTM model, and a better result for monitoring stations in rural areas than those in urban areas.
The prediction of PM2.5 can effectively prevent people from the harm by heavy pollution. However, the existing methods often emphasize the influence of local historical information and neglect the effect of spatial transport. In this paper, we proposed a method, called as long-short-term memory-convolutional neural network (LSTM-CNN), to predict PM2.5 concentration of a specific air quality monitoring station over 6 h using historical PM2.5 concentration data, historical weather data, and time stamp data. The model consisted of two parts: 1) using long-short-term memory networks to model the local variation of PM2.5 concentrations caused by local factors; 2) using one-dimensional convolutional neural networks to model the variation of PM2.5 concentrations caused by spatial transport. We randomly selected 7 monitoring stations in urban and rural areas in Beijing from May 1st 2014 to April 30th 2015 to conduct the evaluation of LSTM-CNN model. The results showed that the proposed LSTM-CNN model could provide a better prediction result than LSTM model, and a better result for monitoring stations in rural areas than those in urban areas.
2020, 38(6): 181-187,93.
doi: 10.13205/j.hjgc.202006030
Abstract:
In order to reduce dust pollution and protect the health of indoor operators in power plants, the pulverized coal particle release model, settling model and gas-particle two-phase flow physical model were established. And multi-phase flow numerical simulation method was used to simulate the dust flow and distribution before and after the treatment of the plant, based on the mechanism of dust floating and flying. The results showed that the dust concentration could be effectively reduced by adjusting the ventilation position of the workshop. Indoor workers could effectively reduce the degree of contamination by using appropriate operation methods and locating in the right direction. It was concluded that the prediction of dust movement law could provide theoretical guidance and basis for dust control in the related industries.
In order to reduce dust pollution and protect the health of indoor operators in power plants, the pulverized coal particle release model, settling model and gas-particle two-phase flow physical model were established. And multi-phase flow numerical simulation method was used to simulate the dust flow and distribution before and after the treatment of the plant, based on the mechanism of dust floating and flying. The results showed that the dust concentration could be effectively reduced by adjusting the ventilation position of the workshop. Indoor workers could effectively reduce the degree of contamination by using appropriate operation methods and locating in the right direction. It was concluded that the prediction of dust movement law could provide theoretical guidance and basis for dust control in the related industries.
2020, 38(6): 188-194,125.
doi: 10.13205/j.hjgc.202006031
Abstract:
Adsorption method is one of the basic methods for VOCs emission treatment. For VOCs emitted with different characteristics, the selection of adsorbent characteristics is also different. In order to provide further guidance for the feature matching promoted adsorption, a novel VOCs analysis method based on the detailed molecular characteristics was introduced in this paper. Through literature survey and field investigation, the VOCs emission data of some key VOCs source industries were collected. Combining the general chemical species and molecular characteristics analysis method, we tried to give a more complete analysis and statistics system to figure out the detailed VOCs emission characteristics of key VOCs emission industries. The statistical properties of VOCs emission could give more effective guidance for the targeted adsorption treatment in the key industries. This comprehensive analysis of VOCs emission characteristic in the key industries would provide an important reference for the selection, evaluation and development of the VOCs emission control technologies.
Adsorption method is one of the basic methods for VOCs emission treatment. For VOCs emitted with different characteristics, the selection of adsorbent characteristics is also different. In order to provide further guidance for the feature matching promoted adsorption, a novel VOCs analysis method based on the detailed molecular characteristics was introduced in this paper. Through literature survey and field investigation, the VOCs emission data of some key VOCs source industries were collected. Combining the general chemical species and molecular characteristics analysis method, we tried to give a more complete analysis and statistics system to figure out the detailed VOCs emission characteristics of key VOCs emission industries. The statistical properties of VOCs emission could give more effective guidance for the targeted adsorption treatment in the key industries. This comprehensive analysis of VOCs emission characteristic in the key industries would provide an important reference for the selection, evaluation and development of the VOCs emission control technologies.
2020, 38(6): 195-201.
doi: 10.13205/j.hjgc.202006032
Abstract:
In order to characterize the Hg distribution characteristics, migration and its release rules of a 600MW unit ultra-low emission coal-fired power, field measurement research was conducted in this paper. The results showed that, the mean value of Hg content in coal was 310μg/kg, and the distribution coefficients of Hg in slag, fly ash, gypsum, waste water and flue gas were 1.9%, 37.5%, 34.6%, 0.8% and 24.8%, respectively. The removal efficiency of Hg in the whole flue gas treatment system was 74.7%, and final total Hg emission was 6.0 μg/m3. The conversion efficiency of SCR and flue gas cooler on Hg0 were 44.2% and 30.4%, respectively. The removal efficiency of HgP in LL-ESP was nearly 100%, and the removal efficiency of Hg2+ in WFGD was 80.7%. The primary release of Hg from the power plant was 783 kg/a (with atmospheric emission of 188 kg/a), and the secondary release was 334 kg/a. This paper could provide references for the release of Hg emission control standards and selection of control technologies for coal-fired power plants.
In order to characterize the Hg distribution characteristics, migration and its release rules of a 600MW unit ultra-low emission coal-fired power, field measurement research was conducted in this paper. The results showed that, the mean value of Hg content in coal was 310μg/kg, and the distribution coefficients of Hg in slag, fly ash, gypsum, waste water and flue gas were 1.9%, 37.5%, 34.6%, 0.8% and 24.8%, respectively. The removal efficiency of Hg in the whole flue gas treatment system was 74.7%, and final total Hg emission was 6.0 μg/m3. The conversion efficiency of SCR and flue gas cooler on Hg0 were 44.2% and 30.4%, respectively. The removal efficiency of HgP in LL-ESP was nearly 100%, and the removal efficiency of Hg2+ in WFGD was 80.7%. The primary release of Hg from the power plant was 783 kg/a (with atmospheric emission of 188 kg/a), and the secondary release was 334 kg/a. This paper could provide references for the release of Hg emission control standards and selection of control technologies for coal-fired power plants.
2020, 38(6): 208-213,258.
doi: 10.13205/j.hjgc.202006034
Abstract:
To solve the problem of environmental pollution caused by the extensive accumulation of the fly ash residue, achieve the maximum utilization value from fly ash and alleviate the shortage of bauxite resources in China, the acid-alkali combination method, which was most commonly used for extracting alumina from fly ash, was combined with block roasting to improve the extraction rate from fly ash. The extraction rate of alumina was greatly improved by lump roasting method. Under the optimum condition, the extraction rate of alumina reached 84%. Through XRD, SEM and other mean, the advantages of blockmaking methods were further analyzed. In addition, the process could not only be used to separate aluminium and silicon, but also recycle sulfuric acid. Kinetic studies showed that the internal capillary channels of fly ash particles and the lumps played a skeleton role similar to that of coke in blast furnaces. Block making treatment created a mesoscopic porous structure for reaction, which not only reduced the distance between solid and liquid phases, but also effectively improved the mass transfer condition of gas and liquid phases, thus enhancing the extraction of aluminium.
To solve the problem of environmental pollution caused by the extensive accumulation of the fly ash residue, achieve the maximum utilization value from fly ash and alleviate the shortage of bauxite resources in China, the acid-alkali combination method, which was most commonly used for extracting alumina from fly ash, was combined with block roasting to improve the extraction rate from fly ash. The extraction rate of alumina was greatly improved by lump roasting method. Under the optimum condition, the extraction rate of alumina reached 84%. Through XRD, SEM and other mean, the advantages of blockmaking methods were further analyzed. In addition, the process could not only be used to separate aluminium and silicon, but also recycle sulfuric acid. Kinetic studies showed that the internal capillary channels of fly ash particles and the lumps played a skeleton role similar to that of coke in blast furnaces. Block making treatment created a mesoscopic porous structure for reaction, which not only reduced the distance between solid and liquid phases, but also effectively improved the mass transfer condition of gas and liquid phases, thus enhancing the extraction of aluminium.
2020, 38(6): 214-220.
doi: 10.13205/j.hjgc.202006035
Abstract:
This study used the Weibull distribution model to analyze China's photovoltaics. Then the neural network model and the market supply A model were used to predict the installed capacity of PV and the amount of modules waste in China. In this paper, we divided PV modules into two phases according to different quality, and considered the four degradation scenarios to predict component scrap. Then we calculated the valuable materials and metal scrap in the components. The results showed that China's PV module will scrap out after 2025. In 2050, China's PV module will scrap up to 60.22 GW, and the accumulative quantity up to 673 GW. In four degradation scenariost, by 2050, typical precious metals will produce up to 3134.5 tons of Ag; the highest yield of rare metals will include 228.1 tons of Te, 463.4 tons of Cd, 58.5 tons of Ga, 29.8 tons of In; for toxic and harmful metals, 263.9 tons of Pb will be produced; and a maximum of 43735.4 tons of Si will be produce. By 2050, the cumulative total waste of PV module materials will reach the peak of 64423193.6 tons.
This study used the Weibull distribution model to analyze China's photovoltaics. Then the neural network model and the market supply A model were used to predict the installed capacity of PV and the amount of modules waste in China. In this paper, we divided PV modules into two phases according to different quality, and considered the four degradation scenarios to predict component scrap. Then we calculated the valuable materials and metal scrap in the components. The results showed that China's PV module will scrap out after 2025. In 2050, China's PV module will scrap up to 60.22 GW, and the accumulative quantity up to 673 GW. In four degradation scenariost, by 2050, typical precious metals will produce up to 3134.5 tons of Ag; the highest yield of rare metals will include 228.1 tons of Te, 463.4 tons of Cd, 58.5 tons of Ga, 29.8 tons of In; for toxic and harmful metals, 263.9 tons of Pb will be produced; and a maximum of 43735.4 tons of Si will be produce. By 2050, the cumulative total waste of PV module materials will reach the peak of 64423193.6 tons.
2020, 38(6): 221-227.
doi: 10.13205/j.hjgc.202006036
Abstract:
The application of recycled concrete can not only reduce the environmental pollution caused by waste concrete landfill, but also solve the problem of insufficient natural stone resources and reuse of waste concrete. Mechanical properties are an important part of the research field of recycled concrete. In this paper, the research progress of mechanical properties of recycled concrete at home and abroad was summarized. The influencing factors including compressive strength, tensile strength, flexural strength, elastic modulus, Poisson’s ratio and strain of recycled concrete and the latest research results were introduced. We also analyzed the shortcomings of the current researches, in order to provide novel ideas for the future research of recycled concrete.
The application of recycled concrete can not only reduce the environmental pollution caused by waste concrete landfill, but also solve the problem of insufficient natural stone resources and reuse of waste concrete. Mechanical properties are an important part of the research field of recycled concrete. In this paper, the research progress of mechanical properties of recycled concrete at home and abroad was summarized. The influencing factors including compressive strength, tensile strength, flexural strength, elastic modulus, Poisson’s ratio and strain of recycled concrete and the latest research results were introduced. We also analyzed the shortcomings of the current researches, in order to provide novel ideas for the future research of recycled concrete.
2020, 38(6): 228-232.
doi: 10.13205/j.hjgc.202006037
Abstract:
In this study, we aimed to find solutions for problems existed in the current permeable bricks properties and manufacturing technology. We evaluated the function of a new type of glass permeable bricks mainly composed of lead-zinc tailings. By secondary sintering, lead-zinc tailings and other raw materials were firstly melted into the basic glass, and then the basic glass was sintered at different temperatures and under different pressing loads, to obtain glass permeable brick samples. The compression strength, rupture strength and permeability coefficient of the samples were tested and analyzed. The results showed that when the sintering temperature was 680 ℃ and the pressing load was 0.82 kN/m2, the function evaluation results of the samples was most satisfactory. And then, the compression strength was 1.90 MPa, the rupture strength was 2.60 MPa, and the permeability coefficient was 0.6 cm/s. In conclusion, the glass permeable brick made from lead-zinc tailings could possess good water permeability and mechanical properties, which provided an effective way for comprehensive utilization of lead-zinc tailings and showed good application prospect.
In this study, we aimed to find solutions for problems existed in the current permeable bricks properties and manufacturing technology. We evaluated the function of a new type of glass permeable bricks mainly composed of lead-zinc tailings. By secondary sintering, lead-zinc tailings and other raw materials were firstly melted into the basic glass, and then the basic glass was sintered at different temperatures and under different pressing loads, to obtain glass permeable brick samples. The compression strength, rupture strength and permeability coefficient of the samples were tested and analyzed. The results showed that when the sintering temperature was 680 ℃ and the pressing load was 0.82 kN/m2, the function evaluation results of the samples was most satisfactory. And then, the compression strength was 1.90 MPa, the rupture strength was 2.60 MPa, and the permeability coefficient was 0.6 cm/s. In conclusion, the glass permeable brick made from lead-zinc tailings could possess good water permeability and mechanical properties, which provided an effective way for comprehensive utilization of lead-zinc tailings and showed good application prospect.
2020, 38(6): 233-239.
doi: 10.13205/j.hjgc.202006038
Abstract:
In order to improve the fermentation efficiency of vegetable waste and reduce the emission of odor to determine the optimal carbon nitrogen ratio of aerobic fermentation. Aerobic fermentation was carried out with vegetable waste as the main material, and pig manure and corn straw as the auxiliary materials. Three C/N ratios (20, 25 and 30) were set to investigate their effects on maturity and odor emission concentration of fermented products. Temperature, moisture content, pH, electrical conductivity (EC), E4/E6, seed germination index and total nitrogen, total phosphorus and total potassium content were used to evaluate the maturity of fermented products. The results showed that: in T1 treatment (C/N=20), the longest duration of high temperature period was 6 days, the seed germination index was up to 82.23%; then its maturation effect was the best, and the content of total nitrogen, total phosphorus and total potassium were increased by 24.22%, 78.94% and 51.45% respectively. In terms of odor emission concentration, the highest emission concentration of NH3 appeared in T2 (C/N=25) treatment group, 368000 μg/m3, the highest emission concentration of H2S appeared in T3 (C/N=30) treatment group, 671 μg/m3; the highest TVOC emission concentration appeared in T1 treatment group, but the maximum difference of TVOC emission concentration between all groups was only 4.3 ppm. Therefore, it was suggested that the optinum C/N ratio of vegetable waste, pig manure and corn straw combined with aerobic compost was 20, which could meet the requirements of harmless aerobic fermentation and reduce the emission of odor.
In order to improve the fermentation efficiency of vegetable waste and reduce the emission of odor to determine the optimal carbon nitrogen ratio of aerobic fermentation. Aerobic fermentation was carried out with vegetable waste as the main material, and pig manure and corn straw as the auxiliary materials. Three C/N ratios (20, 25 and 30) were set to investigate their effects on maturity and odor emission concentration of fermented products. Temperature, moisture content, pH, electrical conductivity (EC), E4/E6, seed germination index and total nitrogen, total phosphorus and total potassium content were used to evaluate the maturity of fermented products. The results showed that: in T1 treatment (C/N=20), the longest duration of high temperature period was 6 days, the seed germination index was up to 82.23%; then its maturation effect was the best, and the content of total nitrogen, total phosphorus and total potassium were increased by 24.22%, 78.94% and 51.45% respectively. In terms of odor emission concentration, the highest emission concentration of NH3 appeared in T2 (C/N=25) treatment group, 368000 μg/m3, the highest emission concentration of H2S appeared in T3 (C/N=30) treatment group, 671 μg/m3; the highest TVOC emission concentration appeared in T1 treatment group, but the maximum difference of TVOC emission concentration between all groups was only 4.3 ppm. Therefore, it was suggested that the optinum C/N ratio of vegetable waste, pig manure and corn straw combined with aerobic compost was 20, which could meet the requirements of harmless aerobic fermentation and reduce the emission of odor.
2020, 38(6): 240-244.
doi: 10.13205/j.hjgc.202006039
Abstract:
A large-scale mercury contaminated site remediation project in Yunnan was the first project in China that used indirect thermal desorption process to remediate mercury-bearing solid waste and mercury-contaminated soil. We obtained relevant construction technology parameters through the engineering practice. When the thermal desorption temperature was 600~750 ℃ and residence time was 40~60 min, the total mercury in remediated material could reach the corresponding targets, which verified the remediation effect of indirect thermal desorption process. The implementation results of this project showed that indirect thermal desorption process had significant remediation effect on high level mercury-bearing solid waste and mercury-contaminated soil, the remediated material reached the corresponding targets, pollutants emission met the Integrated Emission Standard of Air Pollutants (GB 16297—1996) and it had no adverse impact on the environment. The process could also realize the resourcilization and recovery of mercury, and had wide application prospects and engineering reference value.
A large-scale mercury contaminated site remediation project in Yunnan was the first project in China that used indirect thermal desorption process to remediate mercury-bearing solid waste and mercury-contaminated soil. We obtained relevant construction technology parameters through the engineering practice. When the thermal desorption temperature was 600~750 ℃ and residence time was 40~60 min, the total mercury in remediated material could reach the corresponding targets, which verified the remediation effect of indirect thermal desorption process. The implementation results of this project showed that indirect thermal desorption process had significant remediation effect on high level mercury-bearing solid waste and mercury-contaminated soil, the remediated material reached the corresponding targets, pollutants emission met the Integrated Emission Standard of Air Pollutants (GB 16297—1996) and it had no adverse impact on the environment. The process could also realize the resourcilization and recovery of mercury, and had wide application prospects and engineering reference value.
2020, 38(6): 245-251.
doi: 10.13205/j.hjgc.202006040
Abstract:
The soil colloid was extracted by Stoke’s law and the organic matter in the soil was removed by continuous extraction method to obtain mineral colloid. The original soil, soil colloid and mineral colloid were characterized by specific surface area (BET) method and Zeta potential determination. The effects of solution pH, reaction time, initial concentration of U(Ⅵ) and temperature on adsorption of U(Ⅵ) by the three samples were investigated. The results showed that the specific surface area and average pore diameter of the original soil, soil colloid and mineral colloid were 11.5, 31.1, 28.8 m2/g and 18.76, 35.55, 17.5 nm, respectively. When pH was 5.5, the solid-liquid ratio was 1.0 g/L, the temperature was 20 ℃, the initial concentration of U(Ⅵ) was 10.0 mg/L, the reaction time of soil and soil colloid was 50 min and the reaction time of mineral colloid was 40 min, the removal rates of original soil, soil colloid and mineral colloid reached 76.67%, 83.03% and 48.87%, respectively, and the adsorption capacities reached 8.53, 9.24, 5.43 mg/g, respectively. The colloid in soil had obvious adsorption ability on U(Ⅵ) in solution. It had certain reference significance for studying on the treatment of containing U(Ⅵ) wastewater and the migration process of U(Ⅵ) in soil and groundwater.
The soil colloid was extracted by Stoke’s law and the organic matter in the soil was removed by continuous extraction method to obtain mineral colloid. The original soil, soil colloid and mineral colloid were characterized by specific surface area (BET) method and Zeta potential determination. The effects of solution pH, reaction time, initial concentration of U(Ⅵ) and temperature on adsorption of U(Ⅵ) by the three samples were investigated. The results showed that the specific surface area and average pore diameter of the original soil, soil colloid and mineral colloid were 11.5, 31.1, 28.8 m2/g and 18.76, 35.55, 17.5 nm, respectively. When pH was 5.5, the solid-liquid ratio was 1.0 g/L, the temperature was 20 ℃, the initial concentration of U(Ⅵ) was 10.0 mg/L, the reaction time of soil and soil colloid was 50 min and the reaction time of mineral colloid was 40 min, the removal rates of original soil, soil colloid and mineral colloid reached 76.67%, 83.03% and 48.87%, respectively, and the adsorption capacities reached 8.53, 9.24, 5.43 mg/g, respectively. The colloid in soil had obvious adsorption ability on U(Ⅵ) in solution. It had certain reference significance for studying on the treatment of containing U(Ⅵ) wastewater and the migration process of U(Ⅵ) in soil and groundwater.
2020, 38(6): 252-258.
doi: 10.13205/j.hjgc.202006041
Abstract:
The performance of in-situ bio-remediation of petroleum-contaminated soils has been always unsatisfactory, because of complex composition of crude oil and its strong biological toxicity, as well as low microbial activity at low soil temperature. In this paper, 7 cold-adapted oil-degrading bacteria strains were screened and identified from oil polluted soils. Based on the degrading characteristics of the 7 bacteria strains for petroleum composition, 6 cold-adapted oil-degrading microfloras were prepared. The CO2 production and O2 consumption of 6 microfloras for degrading crude oil in 5 L fermenters were monitored online with a gas analyzer. The most efficient microflora, consisted of Arthrobacter sp. JLH 001, Acinetobacter baumannii JLH 002, Pseudomonas fragi JLH 003 and Arthrobacter sp. JLH 006, showed maximal O2 consumption and CO2 production capacity after about 48 h, and completely degraded crude oil (with content of 1%) after about 72 h at 15 ℃, and the degradation was significantly accelerated at 25 ℃. These results suggested that efficient in-situ bio-remediation of petroleum-contaminated soil could be realized by adding cold-adapted oil-degrading microfloras.
The performance of in-situ bio-remediation of petroleum-contaminated soils has been always unsatisfactory, because of complex composition of crude oil and its strong biological toxicity, as well as low microbial activity at low soil temperature. In this paper, 7 cold-adapted oil-degrading bacteria strains were screened and identified from oil polluted soils. Based on the degrading characteristics of the 7 bacteria strains for petroleum composition, 6 cold-adapted oil-degrading microfloras were prepared. The CO2 production and O2 consumption of 6 microfloras for degrading crude oil in 5 L fermenters were monitored online with a gas analyzer. The most efficient microflora, consisted of Arthrobacter sp. JLH 001, Acinetobacter baumannii JLH 002, Pseudomonas fragi JLH 003 and Arthrobacter sp. JLH 006, showed maximal O2 consumption and CO2 production capacity after about 48 h, and completely degraded crude oil (with content of 1%) after about 72 h at 15 ℃, and the degradation was significantly accelerated at 25 ℃. These results suggested that efficient in-situ bio-remediation of petroleum-contaminated soil could be realized by adding cold-adapted oil-degrading microfloras.
