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2023 Vol. 41, No. 3
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2023, 41(3): 1-11,41.
doi: 10.13205/j.hjgc.202303001
Abstract:
In order to improve the quality of the water ecological environment in the urban area of the middle and lower reaches of the Yangtze River, 65 prefecture-level cities in this area were studied and analyzed to clarify the current situations of urban waters from the perspectives of water resources, water quality and aquatic ecology, and to identify problems with urban waters. The results show that the pressure on the water resource is high and still increasing, due to the large quantity of water consumed in the urban areas and the low utilization rate of reclaimed water. The poor quality of urban waters, the degradation of aquatic ecology, and the eutrophication of urban lakes are due to a series of reasons, including the large quantity of sewage and industrial wastewater discharged, the sewer networks in bad maintenance and conditions, the low efficient sewage treatment plants, the heavy runoff pollution loading, the insufficient hydrodynamics, the pror connectivity between waterbodies, and the shrinking lake area, etc. Based on the problem analysis of the urban water ecological environment, the comprehensive remediation of urban waters in the middle and lower reaches of the Yangtze River was divided into three 5-year terms, i.e., the first term (2021—2025), the second term (2026—2030) and the third term (2031—2035), and the objectives, as well as the solutions and roadmap of each stage were proposed correspondingly.
In order to improve the quality of the water ecological environment in the urban area of the middle and lower reaches of the Yangtze River, 65 prefecture-level cities in this area were studied and analyzed to clarify the current situations of urban waters from the perspectives of water resources, water quality and aquatic ecology, and to identify problems with urban waters. The results show that the pressure on the water resource is high and still increasing, due to the large quantity of water consumed in the urban areas and the low utilization rate of reclaimed water. The poor quality of urban waters, the degradation of aquatic ecology, and the eutrophication of urban lakes are due to a series of reasons, including the large quantity of sewage and industrial wastewater discharged, the sewer networks in bad maintenance and conditions, the low efficient sewage treatment plants, the heavy runoff pollution loading, the insufficient hydrodynamics, the pror connectivity between waterbodies, and the shrinking lake area, etc. Based on the problem analysis of the urban water ecological environment, the comprehensive remediation of urban waters in the middle and lower reaches of the Yangtze River was divided into three 5-year terms, i.e., the first term (2021—2025), the second term (2026—2030) and the third term (2031—2035), and the objectives, as well as the solutions and roadmap of each stage were proposed correspondingly.
2023, 41(3): 12-20.
doi: 10.13205/j.hjgc.202303002
Abstract:
Leachate is the main pollution source for groundwater in landfill areas. In this paper, a landfill in a coastal plain area was studied. The migration and remediation of pollutants in groundwater were simulated based on MODFLOW/MT3D modules. The studied working conditions included continuous pollution, cleaned pollution sources and supported pumping wells, and then we simulated the migration and diffusion characteristics of permanganate index in shallow groundwater. The simulation results showed that because of the very small permeability coefficient and the poor hydrodynamic conditions of shallow groundwater aquifers in the coastal plain area, the pollutants mainly affected two aquifers with a depth of less than 10 m; continuous leakage would result in a high content of pollutants in the groundwater plume, but the migration and diffusion distance of pollutants outside the site would be very limited, and after 20 years, the migration distance of pollutants beyond the site boundary would be less than 70 m; setting pumping wells can clean up pollutants effectively, but the groundwater plume removal speed would be very slow, and it would take 5 to 10 years of continuous pumping to shrink the groundwater plume into the site boundary. In the actual repair, the operation and layout of pumping wells can be adjusted according to the repair progress, the pumping wells in the repaired area can be closed, the water yield in the pollution centre can be increased, and pumping wells can be added in the sections with high pollutant concentration to speed up the pollution repair. The simulation model of pollutant transport and remediation established in this study can be used as a reference for the investigation and assessment of the groundwater environment and pollution control in other similar landfill sites.
Leachate is the main pollution source for groundwater in landfill areas. In this paper, a landfill in a coastal plain area was studied. The migration and remediation of pollutants in groundwater were simulated based on MODFLOW/MT3D modules. The studied working conditions included continuous pollution, cleaned pollution sources and supported pumping wells, and then we simulated the migration and diffusion characteristics of permanganate index in shallow groundwater. The simulation results showed that because of the very small permeability coefficient and the poor hydrodynamic conditions of shallow groundwater aquifers in the coastal plain area, the pollutants mainly affected two aquifers with a depth of less than 10 m; continuous leakage would result in a high content of pollutants in the groundwater plume, but the migration and diffusion distance of pollutants outside the site would be very limited, and after 20 years, the migration distance of pollutants beyond the site boundary would be less than 70 m; setting pumping wells can clean up pollutants effectively, but the groundwater plume removal speed would be very slow, and it would take 5 to 10 years of continuous pumping to shrink the groundwater plume into the site boundary. In the actual repair, the operation and layout of pumping wells can be adjusted according to the repair progress, the pumping wells in the repaired area can be closed, the water yield in the pollution centre can be increased, and pumping wells can be added in the sections with high pollutant concentration to speed up the pollution repair. The simulation model of pollutant transport and remediation established in this study can be used as a reference for the investigation and assessment of the groundwater environment and pollution control in other similar landfill sites.
2023, 41(3): 26-33.
doi: 10.13205/j.hjgc.202303004
Abstract:
The mechanism of SO42- removal enhanced by sodium alginate in the lime softening method was explored in this study, by treating the actual desulfurization wastewater with different combinations of lime milk, polymeric ferric sulfate and sodium alginate, through analyzing the SO42- concentration, pH value, Zeta potential, particle size, surface morphology, functional groups and crystal structure after coagulation. The results showed that compared with the dosing of 7 g/L lime and 40 mg/L polymerized iron sulfate at the same time, compounding with sodium alginate could make the SO42- concentration in the effluent decrease from 3991.15 mg/L to 3238.60 mg/L (mean value), and the pH value increase from 9.66 to 9.69 (mean value). Sodium alginate promoted the aggregation of the colloids through the adsorption charge neutralization and adsorption bridging mechanisms, and formed flocs with a median particle size of 30.41 μm at a dosage of 3 mg/L. By adding sodium alginate into the system, the formed CaSO4 crystals were more regular, and the crystal clusters were relatively smaller but quite dense, thus enhancing the removal of SO42-. The infrared spectroscopy and X-ray diffraction analysis indicated that, the carboxyl group (—COO-) of the sodium alginate might facilitate the dissolution of lime by chelating the metal ions such as Ca2+, and the crystallization of CaSO4 was better. The orthogonal experiment results showed that the suitable compound for SO42- removal was composed of 7 g/L of lime, 30 mg/L of polymeric ferric sulfate and 2 mg/L of sodium alginate, and then the removal efficiency was 80.94%.
The mechanism of SO42- removal enhanced by sodium alginate in the lime softening method was explored in this study, by treating the actual desulfurization wastewater with different combinations of lime milk, polymeric ferric sulfate and sodium alginate, through analyzing the SO42- concentration, pH value, Zeta potential, particle size, surface morphology, functional groups and crystal structure after coagulation. The results showed that compared with the dosing of 7 g/L lime and 40 mg/L polymerized iron sulfate at the same time, compounding with sodium alginate could make the SO42- concentration in the effluent decrease from 3991.15 mg/L to 3238.60 mg/L (mean value), and the pH value increase from 9.66 to 9.69 (mean value). Sodium alginate promoted the aggregation of the colloids through the adsorption charge neutralization and adsorption bridging mechanisms, and formed flocs with a median particle size of 30.41 μm at a dosage of 3 mg/L. By adding sodium alginate into the system, the formed CaSO4 crystals were more regular, and the crystal clusters were relatively smaller but quite dense, thus enhancing the removal of SO42-. The infrared spectroscopy and X-ray diffraction analysis indicated that, the carboxyl group (—COO-) of the sodium alginate might facilitate the dissolution of lime by chelating the metal ions such as Ca2+, and the crystallization of CaSO4 was better. The orthogonal experiment results showed that the suitable compound for SO42- removal was composed of 7 g/L of lime, 30 mg/L of polymeric ferric sulfate and 2 mg/L of sodium alginate, and then the removal efficiency was 80.94%.
2023, 41(3): 34-41.
doi: 10.13205/j.hjgc.202303005
Abstract:
Water treatment residual(WTR) can be used as a potential adsorbent to remove heavy metal ions from aqueous solution. The effects of pH value, initial concentration of Hg(Ⅱ), sludge size and temperature on the adsorption performance of WTR as the adsorbent were studied. The kinetics of the adsorption process and adsorption isotherm model were determined, and then its adsorption mechanism was explored. The results showed that the pH of the solution had a great influence on the adsorption of Hg(Ⅱ) by WTR and the adsorption capacity was largest at pH=8.0. A smaller particle size was conductive to the adsorption of Hg(Ⅱ), and the adsorption capacity increased with the increase of initial Hg(Ⅱ) concentration. The adsorption of Hg(Ⅱ) by WTR complied with the pseudo-second-order kinetic model, and the equilibrium isotherm complied with the Langmuir isotherm model, the maximum adsorption capacity was 69.13 mg/g at a temperature of 25 ℃ and pH of 7.0. A higher temperature was conducive to the adsorption of Hg(Ⅱ). It was found that intraparticle diffusion was the rate-limiting step of Hg (Ⅱ) adsorption, by analyzing the changes in the specific surface area and pore size distribution of the WTR before and after adsorption.
Water treatment residual(WTR) can be used as a potential adsorbent to remove heavy metal ions from aqueous solution. The effects of pH value, initial concentration of Hg(Ⅱ), sludge size and temperature on the adsorption performance of WTR as the adsorbent were studied. The kinetics of the adsorption process and adsorption isotherm model were determined, and then its adsorption mechanism was explored. The results showed that the pH of the solution had a great influence on the adsorption of Hg(Ⅱ) by WTR and the adsorption capacity was largest at pH=8.0. A smaller particle size was conductive to the adsorption of Hg(Ⅱ), and the adsorption capacity increased with the increase of initial Hg(Ⅱ) concentration. The adsorption of Hg(Ⅱ) by WTR complied with the pseudo-second-order kinetic model, and the equilibrium isotherm complied with the Langmuir isotherm model, the maximum adsorption capacity was 69.13 mg/g at a temperature of 25 ℃ and pH of 7.0. A higher temperature was conducive to the adsorption of Hg(Ⅱ). It was found that intraparticle diffusion was the rate-limiting step of Hg (Ⅱ) adsorption, by analyzing the changes in the specific surface area and pore size distribution of the WTR before and after adsorption.
2023, 41(3): 42-48.
doi: 10.13205/j.hjgc.202303006
Abstract:
Sludge dewatering is a prerequisite for sludge utilization. In this study, potassium ferrate (K2FeO4) and sludge biochar (sludge biochar obtained by pyrolysis of dehydrated sludge at 500 ℃, recorded as BC500) were used as conditioning agents for sludge pretreatment. After the sewage sludge was conditioned with 3.00 g/L K2FeO4 and 9.00 g/L BC500, the water content of the sludge cake was reduced to 42.33%, which was 36.47 percentage points lower than that in raw sludge cake. The existing forms of residual water in the sludge cake were detected by the low-field nuclear magnetic field. According to the strength of binding energy, residual water was divided into three types: bound water (0.23~10.72 ms) accounting for 99.68%~99.81%, capillary water (70.00~700.00 ms) accounting for 0.19%~0.32%, and free water. The binding energy of water molecules and organic matter was weakened due to oxidation of K2FeO4, and it also made the strongly bound water in the original sludge cake transform into weakly bound water, capillary water or free water; weakly bound water was transformed into capillary water or free water; capillary water was transformed into free water; and free water can be almost completely removed by mechanical dewatering. The imaging results showed that water content in sludge cake was linearly related to the brightness of images. In the production process, real-time online detection results can be used to guide the pressure adjustment of the dewatering process. This research can provide data support and theoretical basis for future deep sludge dewatering study.
Sludge dewatering is a prerequisite for sludge utilization. In this study, potassium ferrate (K2FeO4) and sludge biochar (sludge biochar obtained by pyrolysis of dehydrated sludge at 500 ℃, recorded as BC500) were used as conditioning agents for sludge pretreatment. After the sewage sludge was conditioned with 3.00 g/L K2FeO4 and 9.00 g/L BC500, the water content of the sludge cake was reduced to 42.33%, which was 36.47 percentage points lower than that in raw sludge cake. The existing forms of residual water in the sludge cake were detected by the low-field nuclear magnetic field. According to the strength of binding energy, residual water was divided into three types: bound water (0.23~10.72 ms) accounting for 99.68%~99.81%, capillary water (70.00~700.00 ms) accounting for 0.19%~0.32%, and free water. The binding energy of water molecules and organic matter was weakened due to oxidation of K2FeO4, and it also made the strongly bound water in the original sludge cake transform into weakly bound water, capillary water or free water; weakly bound water was transformed into capillary water or free water; capillary water was transformed into free water; and free water can be almost completely removed by mechanical dewatering. The imaging results showed that water content in sludge cake was linearly related to the brightness of images. In the production process, real-time online detection results can be used to guide the pressure adjustment of the dewatering process. This research can provide data support and theoretical basis for future deep sludge dewatering study.
2023, 41(3): 49-56.
doi: 10.13205/j.hjgc.202303007
Abstract:
This study took five independent polders’ river networks in southern China as the research objects, established a hydrodynamic water quality coupling model according to the characteristics of the tidal reaches, and compared the water quality improvement effects under different gate scheduling strategies. The results showed that: 1) for the polders’ river network, water exchange should be carried out during the spring tide period, and the hydraulic retention time could be shortened by up to 7 hours compared with the neap tide period. Based on the results of the tracer operating condition, for the river network with a short distance between the inlet and outlet gates, the one-way flow scheduling strategy should be used to operate the gate, which could shorten the hydraulic retention time by up to 14.18 hours compared with reciprocal flows. For the river network with a long distance between the inlet and outlet gates, the reciprocal flows operation strategy of opening the gates on both sides to discharge water from the central drainage could shorten the hydraulic retention time by 3.18 hours, compared with the one-way flow scheduling strategy. 2) the results of water quality showed that the deadhead river should be opened up first by water system connection, and then the aforementioned gate scheduling strategy should be adopted. The proportion of the polders’ river network sections whose water quality reached class IV increased by 7.3%. The results of this paper can provide a reference for the improvement of hydrodynamic and water quality for gate scheduling of tidal river networks in different geographical features.
This study took five independent polders’ river networks in southern China as the research objects, established a hydrodynamic water quality coupling model according to the characteristics of the tidal reaches, and compared the water quality improvement effects under different gate scheduling strategies. The results showed that: 1) for the polders’ river network, water exchange should be carried out during the spring tide period, and the hydraulic retention time could be shortened by up to 7 hours compared with the neap tide period. Based on the results of the tracer operating condition, for the river network with a short distance between the inlet and outlet gates, the one-way flow scheduling strategy should be used to operate the gate, which could shorten the hydraulic retention time by up to 14.18 hours compared with reciprocal flows. For the river network with a long distance between the inlet and outlet gates, the reciprocal flows operation strategy of opening the gates on both sides to discharge water from the central drainage could shorten the hydraulic retention time by 3.18 hours, compared with the one-way flow scheduling strategy. 2) the results of water quality showed that the deadhead river should be opened up first by water system connection, and then the aforementioned gate scheduling strategy should be adopted. The proportion of the polders’ river network sections whose water quality reached class IV increased by 7.3%. The results of this paper can provide a reference for the improvement of hydrodynamic and water quality for gate scheduling of tidal river networks in different geographical features.
2023, 41(3): 57-64.
doi: 10.13205/j.hjgc.202303008
Abstract:
Adsorption has become a common method in wastewater treatment because of its unique advantages. In this study, with glutaraldehyde as a cross-linking agent and starch nanocrystals (SNCs) as the substrate, grafting polyethyleneimine (PEI), a novel biosorbent (SNCs-PEI) was successfully prepared. SNCs-PEI was characterized by particle size, zeta potential, Fourier transform infrared spectroscopy (FTIR), and energy dispersive X-ray spectroscopy (EDX). When the value of pH was 3, the Zeta potential of SNCs-PEI was positive 37.9 mV, and it had good adsorption performance on anionic dyes methyl orange (MO) and Congo red (CR). The effects of adsorption time, pH, initial dye concentration and temperature on the absorption capacity of SNCs-PEI were investigated. Under the conditions of pH 3, SNCs-PEI dosage of 0.1 g and initial MO, CR concentration of 130 mg/L, the maximum adsorption capacity of Mo and CR by SNCs-PEI were 82.10, 57.34 mg/g, respectively, according to the fitting of Langmuir isothermal model. The research showed that the adsorption process of MO and CR by SNCs-PEI conformed to the pseudo-second-order kinetics and the Langmuir adsorption model, which was a spontaneous and endothermic process. The study of the new biological adsorbent provides a new way for the removal of industrial wastewater containing anionic dyes.
Adsorption has become a common method in wastewater treatment because of its unique advantages. In this study, with glutaraldehyde as a cross-linking agent and starch nanocrystals (SNCs) as the substrate, grafting polyethyleneimine (PEI), a novel biosorbent (SNCs-PEI) was successfully prepared. SNCs-PEI was characterized by particle size, zeta potential, Fourier transform infrared spectroscopy (FTIR), and energy dispersive X-ray spectroscopy (EDX). When the value of pH was 3, the Zeta potential of SNCs-PEI was positive 37.9 mV, and it had good adsorption performance on anionic dyes methyl orange (MO) and Congo red (CR). The effects of adsorption time, pH, initial dye concentration and temperature on the absorption capacity of SNCs-PEI were investigated. Under the conditions of pH 3, SNCs-PEI dosage of 0.1 g and initial MO, CR concentration of 130 mg/L, the maximum adsorption capacity of Mo and CR by SNCs-PEI were 82.10, 57.34 mg/g, respectively, according to the fitting of Langmuir isothermal model. The research showed that the adsorption process of MO and CR by SNCs-PEI conformed to the pseudo-second-order kinetics and the Langmuir adsorption model, which was a spontaneous and endothermic process. The study of the new biological adsorbent provides a new way for the removal of industrial wastewater containing anionic dyes.
2023, 41(3): 65-73,83.
doi: 10.13205/j.hjgc.202303009
Abstract:
Bioretention system is a green infrastructure which takes advantage of the physical, chemical and biological characteristics of microorganisms and vegetation to regulate the quality and quantity of surface runoff. The bacterial community has a profound influence on the ecological functions of bioretention systems. At present, there are few studies focusing on the structure and diversity of the bacterial community in typical bioretention systems. Nineteen soil samples were collected from three typical bioretention systems in Zhuhai, the structure and diversity of the bacteria community were investigated based on 16S rRNA gene high-throughput sequencing technology, and the relationship between bacterial community and soil environmental factors was discussed, also the predicted ecological functions. The dominant phyla (relative abundance>5%) in three typical bioretention systems were Proteobacteria, Chloroflex, Actinomycetes and Acidobacteria, while the community also contained abundant Firmicutes, Gemmatimonadetes, Nitrospirae, Bacteroidete, Saccharibacteria, Cyanobacteria and Planctomycetes. The diversity and abundance of the bacterial community were relatively high, and the structure of the bacterial community was mainly affected by the vegetation type rather than soil depth. Results indicated that the effects of total organic carbon (TOC), total sulfur (TS), total nitrogen (TN), ammonium-nitrogen (NH4+-N) and nitrate-nitrogen (NO3--N) on bacterial community were strong, while those of pH and nitrite-nitrogen (NO2--N) were weak. The relative abundance of Proteobacteria was negatively correlated with NH4+-N and NO3--N contents, Cloroflexi negatively correlated with TOC and TN, Nitrospirae positively correlated with pH and NO2--N, Bacteroides negatively correlated with NO3--N, and Plantomycetes negatively correlated with NH4+-N. The bacterial community had a relatively complete set of basic ecological functions, including amino acid transport and metabolism, energy production and conversion, signal transduction mechanisms, inorganic ion transport and metabolism, cell wall/membrane/envelope biogenesis, transcription, carbohydrate transport and metabolism, etc.
Bioretention system is a green infrastructure which takes advantage of the physical, chemical and biological characteristics of microorganisms and vegetation to regulate the quality and quantity of surface runoff. The bacterial community has a profound influence on the ecological functions of bioretention systems. At present, there are few studies focusing on the structure and diversity of the bacterial community in typical bioretention systems. Nineteen soil samples were collected from three typical bioretention systems in Zhuhai, the structure and diversity of the bacteria community were investigated based on 16S rRNA gene high-throughput sequencing technology, and the relationship between bacterial community and soil environmental factors was discussed, also the predicted ecological functions. The dominant phyla (relative abundance>5%) in three typical bioretention systems were Proteobacteria, Chloroflex, Actinomycetes and Acidobacteria, while the community also contained abundant Firmicutes, Gemmatimonadetes, Nitrospirae, Bacteroidete, Saccharibacteria, Cyanobacteria and Planctomycetes. The diversity and abundance of the bacterial community were relatively high, and the structure of the bacterial community was mainly affected by the vegetation type rather than soil depth. Results indicated that the effects of total organic carbon (TOC), total sulfur (TS), total nitrogen (TN), ammonium-nitrogen (NH4+-N) and nitrate-nitrogen (NO3--N) on bacterial community were strong, while those of pH and nitrite-nitrogen (NO2--N) were weak. The relative abundance of Proteobacteria was negatively correlated with NH4+-N and NO3--N contents, Cloroflexi negatively correlated with TOC and TN, Nitrospirae positively correlated with pH and NO2--N, Bacteroides negatively correlated with NO3--N, and Plantomycetes negatively correlated with NH4+-N. The bacterial community had a relatively complete set of basic ecological functions, including amino acid transport and metabolism, energy production and conversion, signal transduction mechanisms, inorganic ion transport and metabolism, cell wall/membrane/envelope biogenesis, transcription, carbohydrate transport and metabolism, etc.
2023, 41(3): 74-83.
doi: 10.13205/j.hjgc.202303010
Abstract:
In this work, ferrous sulfate-flocculated sewage sludge (SFS) was activated by Mn(NO3)2 and then pyrolyzed to obtain magnetic adsorbent, which was adopted to remove elemental mercury (Hg0) from flue gas. Results showed that 1) O2 produced by the thermal decomposition of Mn(NO3)2 promoted the decomposition of FeC<em>x during primary pyrolysis of sludge, and that was conducive to the formation of high-valent metal oxides such as Mn4+and Fe3+. The gas produced by the decomposition of Mn(NO3)2 also showed the effect of pore expansion. With the addition of 10% Mn(NO3)2, the specific surface area of the adsorbent reached the maximum (88.5 m2/g), but when the Mn(NO3)2 amount continued to rise, it would produce many crystalline substances and then decreased the specific surface area of the adsorbent. 2) Mn10-SFS showed a maximum mercury removal efficiency of 92.7% at the reaction temperature of 150 ℃. 3) O2 could effectively supplement the active oxygen in the adsorbent, promoting the removal of Hg0, and presence of NO and a low SO2 concentration enhanced Hg0 removal, while H2O vapor and a high concentration of SO2 inhibited it. The Hg0 adsorption and desorption experiment showed that the adsorbent of Mn10-SFS exhibited good renewable recycling performance and stability. After Hg0 capture and regeneration for 5 cycles, the removal efficiency of the adsorbent was not notably degraded.
In this work, ferrous sulfate-flocculated sewage sludge (SFS) was activated by Mn(NO3)2 and then pyrolyzed to obtain magnetic adsorbent, which was adopted to remove elemental mercury (Hg0) from flue gas. Results showed that 1) O2 produced by the thermal decomposition of Mn(NO3)2 promoted the decomposition of FeC<em>x during primary pyrolysis of sludge, and that was conducive to the formation of high-valent metal oxides such as Mn4+and Fe3+. The gas produced by the decomposition of Mn(NO3)2 also showed the effect of pore expansion. With the addition of 10% Mn(NO3)2, the specific surface area of the adsorbent reached the maximum (88.5 m2/g), but when the Mn(NO3)2 amount continued to rise, it would produce many crystalline substances and then decreased the specific surface area of the adsorbent. 2) Mn10-SFS showed a maximum mercury removal efficiency of 92.7% at the reaction temperature of 150 ℃. 3) O2 could effectively supplement the active oxygen in the adsorbent, promoting the removal of Hg0, and presence of NO and a low SO2 concentration enhanced Hg0 removal, while H2O vapor and a high concentration of SO2 inhibited it. The Hg0 adsorption and desorption experiment showed that the adsorbent of Mn10-SFS exhibited good renewable recycling performance and stability. After Hg0 capture and regeneration for 5 cycles, the removal efficiency of the adsorbent was not notably degraded.
2023, 41(3): 84-89,102.
doi: 10.13205/j.hjgc.202303011
Abstract:
In order to study the effect of thermal shock at different temperatures on properties of PPS and PTFE composite filter materials and their coated fabrics, the changes in heat shrinkage, characteristic pore size, pore size distribution and filtration performance of filter materials after 24 h of treatment were compared, under the temperature of 160, 180, 200 ℃. The results showed that latitude and longitude heat shrinkage rate increased with the increase in temperature. After lamination, the membrane played a certain protective role on the filter material, so the longitude and latitude heat shrinkage rate after the coating was lower than the longitude and latitude heat shrinkage rate, before the film was coated. Before the lamination, with the increase of temperature, the median pore size decreased first and then increased, the minimum pore size increased, and the minimum pore size increased to 12.08 μm at 200 ℃; after the lamination, with the increase of temperature, the median aperture and the minimum pore size were increased first and then decreased. Affected by the characteristic aperture and pore size distribution, the pore size distribution of the uncoated film was the most concentrated, mainly distributed between 12.54 μm and 13.25 μm, and its PM2.5 classification filtration efficiency with a grain size of 0.7 to 2.5 μm was about 70%, higher than the filtration efficiency after heating in three groups. After lamination, the pore size distribution was most concentrated when heating at 200 ℃, the classification filtration efficiency was the highest, and the PM2.5 classification filtration efficiency reached 80% above for the fine particulate matter with a grain size of 0.5 to 2.5 μm.
In order to study the effect of thermal shock at different temperatures on properties of PPS and PTFE composite filter materials and their coated fabrics, the changes in heat shrinkage, characteristic pore size, pore size distribution and filtration performance of filter materials after 24 h of treatment were compared, under the temperature of 160, 180, 200 ℃. The results showed that latitude and longitude heat shrinkage rate increased with the increase in temperature. After lamination, the membrane played a certain protective role on the filter material, so the longitude and latitude heat shrinkage rate after the coating was lower than the longitude and latitude heat shrinkage rate, before the film was coated. Before the lamination, with the increase of temperature, the median pore size decreased first and then increased, the minimum pore size increased, and the minimum pore size increased to 12.08 μm at 200 ℃; after the lamination, with the increase of temperature, the median aperture and the minimum pore size were increased first and then decreased. Affected by the characteristic aperture and pore size distribution, the pore size distribution of the uncoated film was the most concentrated, mainly distributed between 12.54 μm and 13.25 μm, and its PM2.5 classification filtration efficiency with a grain size of 0.7 to 2.5 μm was about 70%, higher than the filtration efficiency after heating in three groups. After lamination, the pore size distribution was most concentrated when heating at 200 ℃, the classification filtration efficiency was the highest, and the PM2.5 classification filtration efficiency reached 80% above for the fine particulate matter with a grain size of 0.5 to 2.5 μm.
2023, 41(3): 90-96.
doi: 10.13205/j.hjgc.202303012
Abstract:
Industrial coating volatile organic compounds (VOCs) exhaust gas was selected as the test object, and a fixed-bed pilot plant was designed to conduct VOCs adsorption and desorption tests with the honeycomb activated carbon and zeolite molecular sieve as adsorbents. The results showed that the iodine value, specific surface area, total pore volume and micropore volume of honeycomb activated carbon were larger than those of zeolite molecular sieve, which were 1.79, 2.93, 1.55 and 2.02 times those of zeolite molecular sieve, respectively; under the same desorption temperature and inlet air speed, VOCs were easier to desorb from the surface of honeycomb activated carbon, and the desorption time was much shorter than that of zeolite molecular sieve; under the same reaction conditions, the saturation adsorption capacity of honeycomb activated carbon for VOCs was significantly higher than that of zeolite molecular sieve. Under the same reaction conditions, the saturation adsorption amount of VOCs on honeycomb activated carbon was significantly higher than that on zeolite molecular sieve, but the saturation adsorption amount of zeolite molecular sieve was less affected by the reaction temperature and VOCs concentration; after 10 cycles of adsorption and desorption, the adsorption rate of VOCs on honeycomb activated carbon and zeolite molecular sieve decreased to 71.35% and 81.15% of that of the first time, respectively, and the adsorption and desorption performance of zeolite molecular sieve was more stable. The adsorption and desorption performance of zeolite molecular sieve was more stable. The saturation adsorption capacity of honeycomb activated carbon was large and the desorption time was fast, which was suitable for treating wide load, low air volume and medium to high concentration of VOCs waste gas; zeolite molecular sieve had better aerodynamic and cyclic adsorption and desorption performance, suitable for treating low to medium concentration of VOCs waste gas with a relatively higher initial temperature.
Industrial coating volatile organic compounds (VOCs) exhaust gas was selected as the test object, and a fixed-bed pilot plant was designed to conduct VOCs adsorption and desorption tests with the honeycomb activated carbon and zeolite molecular sieve as adsorbents. The results showed that the iodine value, specific surface area, total pore volume and micropore volume of honeycomb activated carbon were larger than those of zeolite molecular sieve, which were 1.79, 2.93, 1.55 and 2.02 times those of zeolite molecular sieve, respectively; under the same desorption temperature and inlet air speed, VOCs were easier to desorb from the surface of honeycomb activated carbon, and the desorption time was much shorter than that of zeolite molecular sieve; under the same reaction conditions, the saturation adsorption capacity of honeycomb activated carbon for VOCs was significantly higher than that of zeolite molecular sieve. Under the same reaction conditions, the saturation adsorption amount of VOCs on honeycomb activated carbon was significantly higher than that on zeolite molecular sieve, but the saturation adsorption amount of zeolite molecular sieve was less affected by the reaction temperature and VOCs concentration; after 10 cycles of adsorption and desorption, the adsorption rate of VOCs on honeycomb activated carbon and zeolite molecular sieve decreased to 71.35% and 81.15% of that of the first time, respectively, and the adsorption and desorption performance of zeolite molecular sieve was more stable. The adsorption and desorption performance of zeolite molecular sieve was more stable. The saturation adsorption capacity of honeycomb activated carbon was large and the desorption time was fast, which was suitable for treating wide load, low air volume and medium to high concentration of VOCs waste gas; zeolite molecular sieve had better aerodynamic and cyclic adsorption and desorption performance, suitable for treating low to medium concentration of VOCs waste gas with a relatively higher initial temperature.
2023, 41(3): 97-102.
doi: 10.13205/j.hjgc.202303013
Abstract:
The frozen garbage in the waste incineration plant of northern China is usually difficult to dehydrate in winter, which seriously affects the efficiency of waste incineration, and has become a bottleneck problem limiting the development of the waste incineration industry. This study focused on the changes of COD, TOC, NH4+-N, TN and TP in the leachate during anaerobic fermentation of garbage waste under the fermentation temperature of 10 ℃, 20 ℃ and 30 ℃ in the waste storage pit of incineration plant for 10 days. The results showed that at 10 ℃, the concentrations of COD, TOC, TN and NH4+-N in leachate all decreased rapidly within 4 days, and the TP concentration decreased to the minimum value on day 6th. Then the organic indexes gradually increased later and reached the maximum on day 10th. At 20 ℃ and 30 ℃, COD, TOC, NH4+-N and TP concentration decreased gradually in first three days, then increased gradually in the 3rd to 7th day, and decreased gradually in the 7th to 10th day. It was found that the decrease of organic concentration in the leachate at the initial stage was mainly due to the moisture precipitation in the garbage. In the middle stage, macromolecular organic matter in the garbage was degraded into smaller molecular matter and transferred into leachate, and organic matter concentration in leachate increased. In the later stage, the utilization of C, N and P in leachate by microorganisms was the main reason for the decline of each parameter. In addition, when the fermentation temperature of garbage was higher than 20 ℃, and the fermentation time was longer than 3 to 4 days, the macromolecular fiber chain in the garbage was broken, and a large amount of organic matter was degraded and entered the leachate, leading to the decrease of garbage calorific value, affecting the garbage incineration effect. Finally, after comprehensive consideration of multiple factors, such as the change of organic matter in fermentation leachate, the calorific value of waste and the capacity of waste storage pits, it was confirmed that the garbage fermentation temperature and time in storage pit in cold areas should be controlled at 10 to 20 ℃ for 3 to 6 days. The research can provide reference for further research on influencing factors of frozen waste incineration efficiency in cold regions in China.
The frozen garbage in the waste incineration plant of northern China is usually difficult to dehydrate in winter, which seriously affects the efficiency of waste incineration, and has become a bottleneck problem limiting the development of the waste incineration industry. This study focused on the changes of COD, TOC, NH4+-N, TN and TP in the leachate during anaerobic fermentation of garbage waste under the fermentation temperature of 10 ℃, 20 ℃ and 30 ℃ in the waste storage pit of incineration plant for 10 days. The results showed that at 10 ℃, the concentrations of COD, TOC, TN and NH4+-N in leachate all decreased rapidly within 4 days, and the TP concentration decreased to the minimum value on day 6th. Then the organic indexes gradually increased later and reached the maximum on day 10th. At 20 ℃ and 30 ℃, COD, TOC, NH4+-N and TP concentration decreased gradually in first three days, then increased gradually in the 3rd to 7th day, and decreased gradually in the 7th to 10th day. It was found that the decrease of organic concentration in the leachate at the initial stage was mainly due to the moisture precipitation in the garbage. In the middle stage, macromolecular organic matter in the garbage was degraded into smaller molecular matter and transferred into leachate, and organic matter concentration in leachate increased. In the later stage, the utilization of C, N and P in leachate by microorganisms was the main reason for the decline of each parameter. In addition, when the fermentation temperature of garbage was higher than 20 ℃, and the fermentation time was longer than 3 to 4 days, the macromolecular fiber chain in the garbage was broken, and a large amount of organic matter was degraded and entered the leachate, leading to the decrease of garbage calorific value, affecting the garbage incineration effect. Finally, after comprehensive consideration of multiple factors, such as the change of organic matter in fermentation leachate, the calorific value of waste and the capacity of waste storage pits, it was confirmed that the garbage fermentation temperature and time in storage pit in cold areas should be controlled at 10 to 20 ℃ for 3 to 6 days. The research can provide reference for further research on influencing factors of frozen waste incineration efficiency in cold regions in China.
2023, 41(3): 103-110.
doi: 10.13205/j.hjgc.202303014
Abstract:
The combined anaerobic fermentation of sludge and kitchen waste under medium temperature to produce hydrogen is an ideal treatment and disposal technology for both reducing environmental pollution and generating clean energy. Through batch experiment with four factors and a five-level orthogonal design, the effects of four main factors, including kitchen waste C/N, system C/N, moisture content and initial pH value on the hydrogen production from the combined anaerobic fermentation of sludge and kitchen waste based on the hydrogen production performance, and the key factors optimization of conditions were studied under medium temperature condition. The analysis of range and variance showed that the four main factors had an obvious effect on hydrogen production performance, but neither did the interaction of kitchen waste C/N and system C/N. Meanwhile, ignoring the interaction effect, the optimal operational conditions obtained by orthogonal design with the maximum specific hydrogen yield as the dominant indication of biohydrogen performance were: a kitchen waste C/N of 20, combined anaerobic fermentation system C/N of 10, initial pH of 7 and moisture content of 90%, and the corresponding cumulative hydrogen production, specific hydrogen yield, maximum hydrogen production rate and maximum hydrogen concentration was 1499.6 mL, 140.96 mL H2/g DS, 21.73 mL H2/h and 55.79%, respectively.
The combined anaerobic fermentation of sludge and kitchen waste under medium temperature to produce hydrogen is an ideal treatment and disposal technology for both reducing environmental pollution and generating clean energy. Through batch experiment with four factors and a five-level orthogonal design, the effects of four main factors, including kitchen waste C/N, system C/N, moisture content and initial pH value on the hydrogen production from the combined anaerobic fermentation of sludge and kitchen waste based on the hydrogen production performance, and the key factors optimization of conditions were studied under medium temperature condition. The analysis of range and variance showed that the four main factors had an obvious effect on hydrogen production performance, but neither did the interaction of kitchen waste C/N and system C/N. Meanwhile, ignoring the interaction effect, the optimal operational conditions obtained by orthogonal design with the maximum specific hydrogen yield as the dominant indication of biohydrogen performance were: a kitchen waste C/N of 20, combined anaerobic fermentation system C/N of 10, initial pH of 7 and moisture content of 90%, and the corresponding cumulative hydrogen production, specific hydrogen yield, maximum hydrogen production rate and maximum hydrogen concentration was 1499.6 mL, 140.96 mL H2/g DS, 21.73 mL H2/h and 55.79%, respectively.
2023, 41(3): 111-118,128.
doi: 10.13205/j.hjgc.202303015
Abstract:
To mitigate the scaling by landfill leachate pipe transport, this study designed a fouling experiment by placing the pipe materials into the leachate. The computational fluid dynamics modelling was driven by the experimental data, to simulate the scaling process when the leachate flowing a straight pipe and 90° elbow-shaped pipe, respectively. The characteristics of scale deposition regard to the two pipe shapes were discriminated, and the impacts of different factors, including temperature, flow velocity, pipe wall roughness, scale particle size etc., were investigated. The results showed that the proportions of inorganic scale and organic scale in the scales by leachate pipe transport were 75.6% and 24.4%, respectively. The crystal composition of the scales was mainly CaCO3, accompanied by a small amount of NaCl. The scale deposition was positively correlated with temperature, negatively correlated with velocity and scale particle size, while pipe roughness had little effect on the deposition. The scale deposition in the 90° elbow-shaped pipe was larger than that in the straight pipe, and the average deposition rate regarding the straight pipe and 90° elbow pipe was 1.26% and 7.45% by the simulation. The research results can provide insight into the optimal design for the leachate pipe transport system.
To mitigate the scaling by landfill leachate pipe transport, this study designed a fouling experiment by placing the pipe materials into the leachate. The computational fluid dynamics modelling was driven by the experimental data, to simulate the scaling process when the leachate flowing a straight pipe and 90° elbow-shaped pipe, respectively. The characteristics of scale deposition regard to the two pipe shapes were discriminated, and the impacts of different factors, including temperature, flow velocity, pipe wall roughness, scale particle size etc., were investigated. The results showed that the proportions of inorganic scale and organic scale in the scales by leachate pipe transport were 75.6% and 24.4%, respectively. The crystal composition of the scales was mainly CaCO3, accompanied by a small amount of NaCl. The scale deposition was positively correlated with temperature, negatively correlated with velocity and scale particle size, while pipe roughness had little effect on the deposition. The scale deposition in the 90° elbow-shaped pipe was larger than that in the straight pipe, and the average deposition rate regarding the straight pipe and 90° elbow pipe was 1.26% and 7.45% by the simulation. The research results can provide insight into the optimal design for the leachate pipe transport system.
FULVIC ACID SPECTRAL CHARACTERISTICS DURING COMPOSTING OF BIOLEACHING SLUDGE AND DIFFERENT MATERIALS
2023, 41(3): 119-128.
doi: 10.13205/j.hjgc.202303016
Abstract:
Taking the mixed composting of biological leaching sludge and different agricultural and forestry wastes as the research object, ultraviolet-visible spectroscopy (UV-vis), Fourier transform infrared spectroscopy (FTIR) and three-dimensional fluorescence spectroscopy (3D-EEMs) techniques were used to analyze the changes in structure, composition, and content of fulvic acid in the composting process. The basic physical and chemical properties showed that the four treatment groups (T1: sludge+bagasse; T2: sludge+straw; T3: sludge+rice bran; T4: sludge+sawdust) all reached the compost maturity standard. Changes in UV-vis, and UV parameters SUVA254 and SUVA280 indicated that the fulvic acid maturity and aromatic carbon content increased in the four treatment groups, and the T2 treatment group was better than the other treatment groups. FTIR analysis showed that the content of polysaccharides, carbohydrates, and aliphatic substances in fulvic acid was gradually decreasing, while the content of humic substances was gradually increasing. The degree of humification and aromatization in the T3 treatment group was better than that in the other groups. 3D-EEMs analysis showed that organic substances with a simple structure and low degree of conjugation, such as coenzymes and pigments, were degraded and consumed to form humus-like substances with a high degree of conjugation. The fluorescence peak intensity of the T2 treatment group was the highest, indicating the best composting effect. The change in fulvic acid content showed that the decomposing effect of the T3 treatment group was better than that of other treatment groups. So straw and rice brain were proved to be suitable for mixed composting with bioleaching sludge.
Taking the mixed composting of biological leaching sludge and different agricultural and forestry wastes as the research object, ultraviolet-visible spectroscopy (UV-vis), Fourier transform infrared spectroscopy (FTIR) and three-dimensional fluorescence spectroscopy (3D-EEMs) techniques were used to analyze the changes in structure, composition, and content of fulvic acid in the composting process. The basic physical and chemical properties showed that the four treatment groups (T1: sludge+bagasse; T2: sludge+straw; T3: sludge+rice bran; T4: sludge+sawdust) all reached the compost maturity standard. Changes in UV-vis, and UV parameters SUVA254 and SUVA280 indicated that the fulvic acid maturity and aromatic carbon content increased in the four treatment groups, and the T2 treatment group was better than the other treatment groups. FTIR analysis showed that the content of polysaccharides, carbohydrates, and aliphatic substances in fulvic acid was gradually decreasing, while the content of humic substances was gradually increasing. The degree of humification and aromatization in the T3 treatment group was better than that in the other groups. 3D-EEMs analysis showed that organic substances with a simple structure and low degree of conjugation, such as coenzymes and pigments, were degraded and consumed to form humus-like substances with a high degree of conjugation. The fluorescence peak intensity of the T2 treatment group was the highest, indicating the best composting effect. The change in fulvic acid content showed that the decomposing effect of the T3 treatment group was better than that of other treatment groups. So straw and rice brain were proved to be suitable for mixed composting with bioleaching sludge.
2023, 41(3): 129-135,215.
doi: 10.13205/j.hjgc.202303017
Abstract:
In order to improve the efficiency of biological oxidative decomposition of pyrite-containing solid waste from mining and dressing, this paper investigated the effect of saponin on the release of H+, Fe and S in the biological oxidation process of pyrite-containing solid waste from mining and dressing, by using saponin-microorganism-sulfurous iron ore mining solid waste as a reaction system, and its mechanism was discussed. The results showed that it could release 0.55 mmol/g of H+, and 111.4 mg/g of total Fe, as well as 359.3 mg/g of SO42- by adding 30 mg/L saponin and bio-oxidizing for 38 days from the pyrite-containing solid waste of mining and dressing, which were increased by 175%, 82.9% and 39.2%, respectively compared with the blank control group. Firstly, the addition of saponins accelerated the oxidative dissolution of the sendiment layer (jarosite, S0) on the mineral surface, and inhibited the formation of secondary mineral jarosite, thus slowed down the passivation effect. Secondly, it could significantly reduce the contact angle and surface tension between the solution and the mineral surface, and enhance the penetration of Fe3+ in the mineral microporous cracks, so as to accelerate the oxidation and dissolution of pyrite-containing solid waste from mining and dressing. The research results can provide theoretical support for application of saponin in the biological oxidation of pyrite-containing solid waste from mining and dressing.
In order to improve the efficiency of biological oxidative decomposition of pyrite-containing solid waste from mining and dressing, this paper investigated the effect of saponin on the release of H+, Fe and S in the biological oxidation process of pyrite-containing solid waste from mining and dressing, by using saponin-microorganism-sulfurous iron ore mining solid waste as a reaction system, and its mechanism was discussed. The results showed that it could release 0.55 mmol/g of H+, and 111.4 mg/g of total Fe, as well as 359.3 mg/g of SO42- by adding 30 mg/L saponin and bio-oxidizing for 38 days from the pyrite-containing solid waste of mining and dressing, which were increased by 175%, 82.9% and 39.2%, respectively compared with the blank control group. Firstly, the addition of saponins accelerated the oxidative dissolution of the sendiment layer (jarosite, S0) on the mineral surface, and inhibited the formation of secondary mineral jarosite, thus slowed down the passivation effect. Secondly, it could significantly reduce the contact angle and surface tension between the solution and the mineral surface, and enhance the penetration of Fe3+ in the mineral microporous cracks, so as to accelerate the oxidation and dissolution of pyrite-containing solid waste from mining and dressing. The research results can provide theoretical support for application of saponin in the biological oxidation of pyrite-containing solid waste from mining and dressing.
2023, 41(3): 136-142.
doi: 10.13205/j.hjgc.202303018
Abstract:
The long-term leaching rule of heavy metals from steel slag in the wortar was studied by continuous flume leaching test, and the cumulative leaching amount of heavy metals in 30 years was predicted by fitting the leaching kinetic model. The results showed that the steel slag contained heavy metals such as As, Cr, Cu, Mn, Ni, Pb and Zn, and the leaching amount of Cr, Cu, Ni and Zn was higher after the preparation of mortar. With the increase of leaching time, the cumulative leaching amount of heavy metal ions in the solution increased first and then slowed down; the longer the pre-curing age of the mortar was, the lower the cumulative leaching amount of heavy metals was, and the more obvious the solidification effect on Zn was. The leaching law of Cr and Ni, Cu and Zn in cement mortar conformed to the Elovich equation and double constant rate equation, respectively the leaching law of Cu in steel slag mortar conformed to the double constant rate equation, and the leaching law of Cr, Ni and Zn conformed to the second order kinetic equation. According to the calculation of the kinetic equation, it was predicted that the cumulative leaching amount of Cr, Cu, Ni and Zn in steel slag mortar and pure cement mortar in 30 years was reduced by 49.52%, 24.02%, 47.20% and 89.79%, respectively.
The long-term leaching rule of heavy metals from steel slag in the wortar was studied by continuous flume leaching test, and the cumulative leaching amount of heavy metals in 30 years was predicted by fitting the leaching kinetic model. The results showed that the steel slag contained heavy metals such as As, Cr, Cu, Mn, Ni, Pb and Zn, and the leaching amount of Cr, Cu, Ni and Zn was higher after the preparation of mortar. With the increase of leaching time, the cumulative leaching amount of heavy metal ions in the solution increased first and then slowed down; the longer the pre-curing age of the mortar was, the lower the cumulative leaching amount of heavy metals was, and the more obvious the solidification effect on Zn was. The leaching law of Cr and Ni, Cu and Zn in cement mortar conformed to the Elovich equation and double constant rate equation, respectively the leaching law of Cu in steel slag mortar conformed to the double constant rate equation, and the leaching law of Cr, Ni and Zn conformed to the second order kinetic equation. According to the calculation of the kinetic equation, it was predicted that the cumulative leaching amount of Cr, Cu, Ni and Zn in steel slag mortar and pure cement mortar in 30 years was reduced by 49.52%, 24.02%, 47.20% and 89.79%, respectively.
2023, 41(3): 143-147.
doi: 10.13205/j.hjgc.202303019
Abstract:
In order to realize the resource utilization of industrial solid waste, the effect of composite cementitious materials prepared from steel slag, water slag and desulfurized gypsum as the admixtures, on the properties of paste and concrete was studied. The result showed that: The water requirement of normal consistency and setting time of the pure slurry were positively correlated with the amount of composite cementitious material; the compressive strength of the prepared concrete decreased as the amount of cement replaced by the composite cementitious material increased. The 28 d compressive strength of whole concrete blocks prepared with composite cementitious materials was 43.5 MPa, which was 78.3% of the cement control group. The research showed that steel slag powder and desulfurized gypsum could promote the hydration of water slag to form hydration products including calcium vanadium stone and calcium silicate hydrate, which played a good cementation role to make the concrete structure dense and obtain good performance. The partial substitution for cement of composite cementitious material would reduce CO2 emissions, bring economic and environmental benefits, and have broad market application prospects.
In order to realize the resource utilization of industrial solid waste, the effect of composite cementitious materials prepared from steel slag, water slag and desulfurized gypsum as the admixtures, on the properties of paste and concrete was studied. The result showed that: The water requirement of normal consistency and setting time of the pure slurry were positively correlated with the amount of composite cementitious material; the compressive strength of the prepared concrete decreased as the amount of cement replaced by the composite cementitious material increased. The 28 d compressive strength of whole concrete blocks prepared with composite cementitious materials was 43.5 MPa, which was 78.3% of the cement control group. The research showed that steel slag powder and desulfurized gypsum could promote the hydration of water slag to form hydration products including calcium vanadium stone and calcium silicate hydrate, which played a good cementation role to make the concrete structure dense and obtain good performance. The partial substitution for cement of composite cementitious material would reduce CO2 emissions, bring economic and environmental benefits, and have broad market application prospects.
2023, 41(3): 148-154.
doi: 10.13205/j.hjgc.202303020
Abstract:
For most landfills, membrane filtration has become a common method for leachate treatment. The filtered concentrated leachate is usually recirculated back to the landfill for such operation is convenient, of low investment and running cost. However, concentrated leachate has characteristics of high salt and poor degradability, which might affect landfill gas production and the effluent quality of leachate after injection. In this study, the nanofiltration concentrate was periodically reinjected into simulating bioreactors filled with waste samples of high/low organic content collected from the landfill site. And then the methanogenesis, odor gas and leachate quality were monitored. The experimental results showed that compared with the injection of water (blank and control), the reinjection of concentrated liquid had an inhibitory effect on methanogenesis process, and the inhibition for low organic waste was stronger. After the injection of the concentrated leachate, the release of ammonia and hydrogen sulfide became stronger. The odor gases were mainly released in rapid methanogenesis phase and the methanogenic attenuation phase. With the increase of the reinjection cycles, the reinjection of concentrated leachate showed good removal effect on COD, BOD5, ammonia nitrogen, total nitrogen and oil in the effluent, but it also led to the rise of salt concentration in the effluent, even higher than the original concentrated leachate.
For most landfills, membrane filtration has become a common method for leachate treatment. The filtered concentrated leachate is usually recirculated back to the landfill for such operation is convenient, of low investment and running cost. However, concentrated leachate has characteristics of high salt and poor degradability, which might affect landfill gas production and the effluent quality of leachate after injection. In this study, the nanofiltration concentrate was periodically reinjected into simulating bioreactors filled with waste samples of high/low organic content collected from the landfill site. And then the methanogenesis, odor gas and leachate quality were monitored. The experimental results showed that compared with the injection of water (blank and control), the reinjection of concentrated liquid had an inhibitory effect on methanogenesis process, and the inhibition for low organic waste was stronger. After the injection of the concentrated leachate, the release of ammonia and hydrogen sulfide became stronger. The odor gases were mainly released in rapid methanogenesis phase and the methanogenic attenuation phase. With the increase of the reinjection cycles, the reinjection of concentrated leachate showed good removal effect on COD, BOD5, ammonia nitrogen, total nitrogen and oil in the effluent, but it also led to the rise of salt concentration in the effluent, even higher than the original concentrated leachate.
2023, 41(3): 155-162.
doi: 10.13205/j.hjgc.202303021
Abstract:
A pot experiment was conducted to study the tolerance and enrichment characteristics of four herbs (fescue, ryegrass, vetch, and alfalfa), which are commonly used as the remediation plants for organic contaminated soil under the stress of tris-(1-chloro-2-propyl) phosphate (TCIPP), to screen potential plants with high remediation capability for phytoremediation to TCIPP contaminated soil. The results showed that TCIPP could inhibit the growth and development of four herbs, but only the biomass of ryegrass decreased significantly, and the biomass of the other three herbs did not decrease significantly. The concentration distribution of TCIPP in the tissues of four herbs was leaf>root>stem, indicating that TCIPP was easy to migrate from plant roots to aboveground. Among the four herbs, the concentration and accumulation of TCIPP in the leaf of vetch were the highest, 15.0 mg/kg and 34.9 mg/pot, respectively. Vetch and alfalfa had a relatively high efficiency in absorbing, accumulating and transporting TCIPP from the soil. Their shoot concentration factors were 1.39 and 1.50, and the translocation factors were 2.61 and 3.24, respectively. The four herbs had good remediation capability to TCIPP contaminated soil, and their removal rates of TCIPP in soil were 64.7% to 91.6%. Among them, the removal rate of TCIPP in the rhizosphere soil of ryegrass was the highest. However, the phytoextraction rates were less than 2%, indicating that the removal of TCIPP in soil was mainly caused by the degradation of rhizosphere microorganisms. Based on the comprehensive comparison of the tolerance, enrichment characteristics, and removal rates of four herbs for TCIPP in soil, we suggested that ryegrass can be given priority as a remediation plant for TCIPP-contaminated soil.
A pot experiment was conducted to study the tolerance and enrichment characteristics of four herbs (fescue, ryegrass, vetch, and alfalfa), which are commonly used as the remediation plants for organic contaminated soil under the stress of tris-(1-chloro-2-propyl) phosphate (TCIPP), to screen potential plants with high remediation capability for phytoremediation to TCIPP contaminated soil. The results showed that TCIPP could inhibit the growth and development of four herbs, but only the biomass of ryegrass decreased significantly, and the biomass of the other three herbs did not decrease significantly. The concentration distribution of TCIPP in the tissues of four herbs was leaf>root>stem, indicating that TCIPP was easy to migrate from plant roots to aboveground. Among the four herbs, the concentration and accumulation of TCIPP in the leaf of vetch were the highest, 15.0 mg/kg and 34.9 mg/pot, respectively. Vetch and alfalfa had a relatively high efficiency in absorbing, accumulating and transporting TCIPP from the soil. Their shoot concentration factors were 1.39 and 1.50, and the translocation factors were 2.61 and 3.24, respectively. The four herbs had good remediation capability to TCIPP contaminated soil, and their removal rates of TCIPP in soil were 64.7% to 91.6%. Among them, the removal rate of TCIPP in the rhizosphere soil of ryegrass was the highest. However, the phytoextraction rates were less than 2%, indicating that the removal of TCIPP in soil was mainly caused by the degradation of rhizosphere microorganisms. Based on the comprehensive comparison of the tolerance, enrichment characteristics, and removal rates of four herbs for TCIPP in soil, we suggested that ryegrass can be given priority as a remediation plant for TCIPP-contaminated soil.
2023, 41(3): 163-171.
doi: 10.13205/j.hjgc.202303022
Abstract:
In situ thermal desorption (ISTD), as a kind of physical soil remediation technology, has the advantages of in situ disposal of contaminated soil, less secondary pollution, simpler process principle, and higher efficiency and flexibility. In view of the problems of low removal efficiency and energy waste caused by unreasonable arrangement and neglection of thermal insulation measures in the actual process of soil remediation, COMSOL Multiphysics software was used to simulate the 1000 h heating process of contaminated soil. Based on the model verification, the effects of different arrangement methods, spacing of heating wells and thermal insulation measures on soil heating process were discussed. The results showed that when treating pollutants with a boiling point above 200 ℃, the triangular arrangement of 1.5 m heating well spacing could meet the treatment temperature requirements faster, and the energy consumption was relatively lower. Applying thermal insulation measures on the soil surface could not only prevent the leakage of polluted gas, but also effectively improve the thermal efficiency of soil heating process. In the triangular arrangement, the thermal efficiency was relatively increased by 11.667% after thermal insulation measures applied with a distance of 2.0 m between heating wells.
In situ thermal desorption (ISTD), as a kind of physical soil remediation technology, has the advantages of in situ disposal of contaminated soil, less secondary pollution, simpler process principle, and higher efficiency and flexibility. In view of the problems of low removal efficiency and energy waste caused by unreasonable arrangement and neglection of thermal insulation measures in the actual process of soil remediation, COMSOL Multiphysics software was used to simulate the 1000 h heating process of contaminated soil. Based on the model verification, the effects of different arrangement methods, spacing of heating wells and thermal insulation measures on soil heating process were discussed. The results showed that when treating pollutants with a boiling point above 200 ℃, the triangular arrangement of 1.5 m heating well spacing could meet the treatment temperature requirements faster, and the energy consumption was relatively lower. Applying thermal insulation measures on the soil surface could not only prevent the leakage of polluted gas, but also effectively improve the thermal efficiency of soil heating process. In the triangular arrangement, the thermal efficiency was relatively increased by 11.667% after thermal insulation measures applied with a distance of 2.0 m between heating wells.
2023, 41(3): 172-178.
doi: 10.13205/j.hjgc.202303023
Abstract:
In recent years, a large number of abandoned masks cause resource waste and potential environmental risks in incineration and landfill. It is urgent to find an eco-friendly, economic and feasible disposal method for them. In the present work, hydrophobic modification of the abandoned masks with sodium hydroxide, TEOS and octadecyltrichlorosilane was conducted. Through scanning electron microscopy (SEM), infrared spectroscopy (ATR-FTIR) and contact angle measurement, it was found that a complete and uniform hydrophobic coating was formed on the surface of the modified masks, and the water contact angle reached 141.1°. The adsorption capacity of the modified masks for lubricating oil and soybean oil reached 28.52 g/g and 26.84 g/g, respectively. After 10 cycles of adsorption and desorption, the oil absorption performance remained stable. This study provides a new way for the resource utilization of waste masks and tells their good application prospect.
In recent years, a large number of abandoned masks cause resource waste and potential environmental risks in incineration and landfill. It is urgent to find an eco-friendly, economic and feasible disposal method for them. In the present work, hydrophobic modification of the abandoned masks with sodium hydroxide, TEOS and octadecyltrichlorosilane was conducted. Through scanning electron microscopy (SEM), infrared spectroscopy (ATR-FTIR) and contact angle measurement, it was found that a complete and uniform hydrophobic coating was formed on the surface of the modified masks, and the water contact angle reached 141.1°. The adsorption capacity of the modified masks for lubricating oil and soybean oil reached 28.52 g/g and 26.84 g/g, respectively. After 10 cycles of adsorption and desorption, the oil absorption performance remained stable. This study provides a new way for the resource utilization of waste masks and tells their good application prospect.
2023, 41(3): 179-184,191.
doi: 10.13205/j.hjgc.202303024
Abstract:
Aiming at the problems such as complex system, large maintenance and measurement delay in the pretreatment of gas on-line monitoring in industrial process, the in-situ permeation tube pretreatment device is developed based on the physical characteristics of microporous ceramics and aerodynamics principle. The pretreatment device mainly includes two laser emitters and a permeation tube cavity. When the gas flows through the permeation tube, the pressure drop will be formed before and after the wall of the incoming direction, due to the action of flow around. Under the pressure drop, the gas will be filtered through the permeation tube and then enter the tube to be measured by laser. Firstly, the coupling field of pipe and permeation tube are simulated by CFD numerical simulation, and it is shown that under the condition of single variable, the gas renewal rate increases with the increase of flow rate and inner diameter, and decreases with the increase of outer diameter. Then the experimental device is set up for experimental verification, and the result is consistent with the flow field simulation. On this basis, the in-situ permeation tube pretreatment device is developed and applied in the field, and the portable analyzer is used for comparison which show the error between them is less than 2%. Compared with the existing pretreatment devices, the permeation tube cavity is installed in the pipe, the measurement environment is consistent with the working condition, and the sampling path is short, which can realize high fidelity and fast on-line monitoring of industrial process gas.
Aiming at the problems such as complex system, large maintenance and measurement delay in the pretreatment of gas on-line monitoring in industrial process, the in-situ permeation tube pretreatment device is developed based on the physical characteristics of microporous ceramics and aerodynamics principle. The pretreatment device mainly includes two laser emitters and a permeation tube cavity. When the gas flows through the permeation tube, the pressure drop will be formed before and after the wall of the incoming direction, due to the action of flow around. Under the pressure drop, the gas will be filtered through the permeation tube and then enter the tube to be measured by laser. Firstly, the coupling field of pipe and permeation tube are simulated by CFD numerical simulation, and it is shown that under the condition of single variable, the gas renewal rate increases with the increase of flow rate and inner diameter, and decreases with the increase of outer diameter. Then the experimental device is set up for experimental verification, and the result is consistent with the flow field simulation. On this basis, the in-situ permeation tube pretreatment device is developed and applied in the field, and the portable analyzer is used for comparison which show the error between them is less than 2%. Compared with the existing pretreatment devices, the permeation tube cavity is installed in the pipe, the measurement environment is consistent with the working condition, and the sampling path is short, which can realize high fidelity and fast on-line monitoring of industrial process gas.
2023, 41(3): 185-191.
doi: 10.13205/j.hjgc.202303025
Abstract:
The effect of agent injection in-situ is the key to the results of site remediation. Therefore, evaluating the effect of agent injection is of great significance to site in-situ remediation. In this paper, the effect of agent injection in the process of in-situ repairing a coking site in Yunnan was evaluated by using the cross-hole earth resistance imaging method (ERT). The transmission and distribution of the repairing agent were estimated according to the underground electrical information and electrical changes before, during and after perfusion. The results showed that the changes in water temperature, pH, conductivity, redox potential, dissolved oxygen and other basic water quality parameters of the groundwater in the monitoring wells before and after the injection, were basically consistent with the electrical changes of the 2D and 3D profiles of the site, indicating that the injection effect of the repair agent was good, and it was confirmed that ERT had good feasibility and applicability in the evaluation of injection effect of the in-situ repairing agents, which can provide a reference for the in-situ repairing of similar sites.
The effect of agent injection in-situ is the key to the results of site remediation. Therefore, evaluating the effect of agent injection is of great significance to site in-situ remediation. In this paper, the effect of agent injection in the process of in-situ repairing a coking site in Yunnan was evaluated by using the cross-hole earth resistance imaging method (ERT). The transmission and distribution of the repairing agent were estimated according to the underground electrical information and electrical changes before, during and after perfusion. The results showed that the changes in water temperature, pH, conductivity, redox potential, dissolved oxygen and other basic water quality parameters of the groundwater in the monitoring wells before and after the injection, were basically consistent with the electrical changes of the 2D and 3D profiles of the site, indicating that the injection effect of the repair agent was good, and it was confirmed that ERT had good feasibility and applicability in the evaluation of injection effect of the in-situ repairing agents, which can provide a reference for the in-situ repairing of similar sites.
2023, 41(3): 192-201.
doi: 10.13205/j.hjgc.202303026
Abstract:
In response to the environmental protection goal of "reducing pollution and carbon, collaborative governance, improving", a new process of equivalent greenhouse gas and malodorous gas treatment based on the original "water absorption-photocatalysis-chemical absorption" treatment process had been transformed into a "water absorption-alkali absorption-regenerative incineration (RTO)-quench-alkali absorption," which aimed at greenhouse gas methane and malodorous gas of the anaerobic tank in the sewage station of the pharmaceutical industry. Life cycle assessment (LCA) was used to implement characteristic and standardized analysis of the environmental impact of the waste gas treatment process. The results showed that the significant environmental impact of the original and new waste gas treatment process was global warming. Through the greenhouse gas reduction calculation and economic evaluation, compared with the original process, the new process could reach the annual greenhouse effect reduction value of 7.53×106 kg CO2-eq and an economic benefit of RMB 1.21×106. The new process provided a theoretical basis for comprehensively developing the pharmaceutical industry’s environmental, technological, economic, and social benefits while achieving efficient waste gas treatment.
In response to the environmental protection goal of "reducing pollution and carbon, collaborative governance, improving", a new process of equivalent greenhouse gas and malodorous gas treatment based on the original "water absorption-photocatalysis-chemical absorption" treatment process had been transformed into a "water absorption-alkali absorption-regenerative incineration (RTO)-quench-alkali absorption," which aimed at greenhouse gas methane and malodorous gas of the anaerobic tank in the sewage station of the pharmaceutical industry. Life cycle assessment (LCA) was used to implement characteristic and standardized analysis of the environmental impact of the waste gas treatment process. The results showed that the significant environmental impact of the original and new waste gas treatment process was global warming. Through the greenhouse gas reduction calculation and economic evaluation, compared with the original process, the new process could reach the annual greenhouse effect reduction value of 7.53×106 kg CO2-eq and an economic benefit of RMB 1.21×106. The new process provided a theoretical basis for comprehensively developing the pharmaceutical industry’s environmental, technological, economic, and social benefits while achieving efficient waste gas treatment.
2023, 41(3): 202-209,228.
doi: 10.13205/j.hjgc.202303027
Abstract:
Volatile organic compounds (VOCs) pollution in the printing industry has attracted increasing attention, and certain achievements have been made after continuous rectification in recent years. However, we are facing staged governance bottlenecks and urgently need to carry out in-depth governance work. For the sake of understanding the current problems in the management and control of VOCs in the printing industry, this study analyzed the scale and geographical distribution of the printing industry, ink classification and VOCs emission, and substitutability of raw and auxiliary materials containing VOCs, and emission reduction potential of the printing industry through data search, industry association research, and on-site survey for printing enterprises. Additionally, industry development, application of printing and governance technology, and VOCs management were compared with the developed countries. It was pointed out that there were problems in China’s printing industry, such as small scale and low concentration of enterprises, the relatively backward printing and governance technology, and the uneven governance technology. The following suggestions were put forward for in-depth treatment of VOCs: 1) enterprises with different printing processes should implement classified policies and precise management and control. It was recommended to appropriately supplement emission standards, conduct differentiated environmental impact assessment reviews for newly, renovated and expanded enterprises, strictly implement the pollutants discharge permit system, and implement differentiated management of VOCs enterprises in emergency control of heavy pollution weather, pollution weather response, and environmental law enforcement. 2) Policy guidance, fiscal and taxation support should be carried out, and promote printing industry scale and centralized management would be promoted by adjusting industrial structure, controlling the environmental access policy, and increasing fiscal, taxation, incentives and subsidies.
Volatile organic compounds (VOCs) pollution in the printing industry has attracted increasing attention, and certain achievements have been made after continuous rectification in recent years. However, we are facing staged governance bottlenecks and urgently need to carry out in-depth governance work. For the sake of understanding the current problems in the management and control of VOCs in the printing industry, this study analyzed the scale and geographical distribution of the printing industry, ink classification and VOCs emission, and substitutability of raw and auxiliary materials containing VOCs, and emission reduction potential of the printing industry through data search, industry association research, and on-site survey for printing enterprises. Additionally, industry development, application of printing and governance technology, and VOCs management were compared with the developed countries. It was pointed out that there were problems in China’s printing industry, such as small scale and low concentration of enterprises, the relatively backward printing and governance technology, and the uneven governance technology. The following suggestions were put forward for in-depth treatment of VOCs: 1) enterprises with different printing processes should implement classified policies and precise management and control. It was recommended to appropriately supplement emission standards, conduct differentiated environmental impact assessment reviews for newly, renovated and expanded enterprises, strictly implement the pollutants discharge permit system, and implement differentiated management of VOCs enterprises in emergency control of heavy pollution weather, pollution weather response, and environmental law enforcement. 2) Policy guidance, fiscal and taxation support should be carried out, and promote printing industry scale and centralized management would be promoted by adjusting industrial structure, controlling the environmental access policy, and increasing fiscal, taxation, incentives and subsidies.
2023, 41(3): 210-215.
doi: 10.13205/j.hjgc.202303028
Abstract:
In 2018, China put forward a pilot project to construct Zero-Waste City. Through the investigation of the research area of one of the pilot cities, it was found that the domestic waste produced in this area showed a trend of rapid non-linear growth in recent years. Traditional predicting methods can no longer meet the expected delicacy management demand of local waste production. It is challenging to coordinate the development of local waste treatment capacity with the production increasing. Therefore, based on the urban multi-social data with the annual unit, a model research plan for predicting the overall waste production of the study area was proposed. Combining of the grey relational analysis algorithm and LightGBM machine learning algorithm can get several types of feature data in the multi-social data, which are most closely related to the growth of waste generation in the study area. The machine learning model construction and cross-validation tuning to obtain the domestic waste production prediction model with an MAE of 1.48 and an MAPE of 15.42%. Finally, the model predicted that domestic waste production in 2025 will reach 172,300 tons/year.
In 2018, China put forward a pilot project to construct Zero-Waste City. Through the investigation of the research area of one of the pilot cities, it was found that the domestic waste produced in this area showed a trend of rapid non-linear growth in recent years. Traditional predicting methods can no longer meet the expected delicacy management demand of local waste production. It is challenging to coordinate the development of local waste treatment capacity with the production increasing. Therefore, based on the urban multi-social data with the annual unit, a model research plan for predicting the overall waste production of the study area was proposed. Combining of the grey relational analysis algorithm and LightGBM machine learning algorithm can get several types of feature data in the multi-social data, which are most closely related to the growth of waste generation in the study area. The machine learning model construction and cross-validation tuning to obtain the domestic waste production prediction model with an MAE of 1.48 and an MAPE of 15.42%. Finally, the model predicted that domestic waste production in 2025 will reach 172,300 tons/year.
2023, 41(3): 216-221.
doi: 10.13205/j.hjgc.202303029
Abstract:
Based on the sampling survey of domestic waste in 72 typical villages and towns in 12 provinces, the impacts of waste composition, water content, wet base low calorific value, fertilizer efficiency indicators (organic matter, TN, TP, TK) and heavy metal content on the feasibility of incineration, composting and landfill technology was systematically analyzed. The results showed that the wet base low calorific value of the whole components, combustible components, and combustible components except kitchen waste of village and town domestic waste were 4263, 5652, 13772 kJ/kg, respectively. The wet base low calorific value of village and town domestic waste could be significantly increased in the process of sorting after incineration. The organic matter, water content, nitrogen, phosphorus, potassium content and some other indexes of the household garbage in villages and towns basically meet the requirements of composting treatment. Composting treatment can be carried out, but Cd content in some areas exceeds the standard. Therefore, source classification should be strengthened to control the quality of composting products and reduce environmental risks. Classified recycling of recyclable waste and hazardous waste before the landfill treatment of rural domestic waste can reduce the amount of landfill waste by about 1/3, and ultimately reduce the pollution risk of landfill leachate.
Based on the sampling survey of domestic waste in 72 typical villages and towns in 12 provinces, the impacts of waste composition, water content, wet base low calorific value, fertilizer efficiency indicators (organic matter, TN, TP, TK) and heavy metal content on the feasibility of incineration, composting and landfill technology was systematically analyzed. The results showed that the wet base low calorific value of the whole components, combustible components, and combustible components except kitchen waste of village and town domestic waste were 4263, 5652, 13772 kJ/kg, respectively. The wet base low calorific value of village and town domestic waste could be significantly increased in the process of sorting after incineration. The organic matter, water content, nitrogen, phosphorus, potassium content and some other indexes of the household garbage in villages and towns basically meet the requirements of composting treatment. Composting treatment can be carried out, but Cd content in some areas exceeds the standard. Therefore, source classification should be strengthened to control the quality of composting products and reduce environmental risks. Classified recycling of recyclable waste and hazardous waste before the landfill treatment of rural domestic waste can reduce the amount of landfill waste by about 1/3, and ultimately reduce the pollution risk of landfill leachate.
2023, 41(3): 222-228.
doi: 10.13205/j.hjgc.202303030
Abstract:
Facing with the "double carbon" target of China, the importance of greenhouse gas (GHG) emission accounting and data quality management has gradually increased. Electricity emission is an important emission source of enterprises, and the electricity emission factors will directly affect the accounting results. On the basis of the published date such as Yearbook 2022, the regional electricity emission factors and provincial electricity emission factors for 2020 were calculated and compared with the data in 2010. The results showed that the power emission factor in 2020 was decreasing compared with that in 2010, and the difference between regions was increasing. The average deviation rate of the provincial grid emission factors from their corresponding regional grid emission factors reached 23% in 2020. Compared with regional electricity emission factors, provincial electricity emission factors were more accurate in accounting results, and significantly improved the quality date for greenhouse gas emission accounting, so they were more suitable for estimating electricity implied emissions.
Facing with the "double carbon" target of China, the importance of greenhouse gas (GHG) emission accounting and data quality management has gradually increased. Electricity emission is an important emission source of enterprises, and the electricity emission factors will directly affect the accounting results. On the basis of the published date such as Yearbook 2022, the regional electricity emission factors and provincial electricity emission factors for 2020 were calculated and compared with the data in 2010. The results showed that the power emission factor in 2020 was decreasing compared with that in 2010, and the difference between regions was increasing. The average deviation rate of the provincial grid emission factors from their corresponding regional grid emission factors reached 23% in 2020. Compared with regional electricity emission factors, provincial electricity emission factors were more accurate in accounting results, and significantly improved the quality date for greenhouse gas emission accounting, so they were more suitable for estimating electricity implied emissions.
2023, 41(3): 237-242.
doi: 10.13205/j.hjgc.202303032
Abstract:
The situation of water resources, water supply and use, sewage treatment and recycling in Japan were systematically summarized and analyzed. Overall, the whole country of Japan has relatively adequate water, but some areas, like the Kanto coast, Kitakyushu and the East Sea, are short of water. The combined annual per capita water consumption of Japan remains stable at around 630 m3, which is about 1.5 times that of China. The total amount of sewage treatment in Japan is 14.64 billion m3, and the average cost of sewage treatment is 143.3 yen/m3 in 2018. The total amount of reclaimed water utilization in Japan is stable at around 200 million m3 per year, and the utilization rate of reclaimed water is below 1.5%. Large cities, like Tokyo, have a significantly higher utilization rate of centralized reclaimed water of 3.2%, obviously higher than the national average value. Japan uses reclaimed water in a wide range of ways, and the classified statistics of reclaimed water are meticulous and comprehensive, including flushing, landscape environment, snow melting and other nine uses. Reclaimed water is mainly used to supplement surface water, water for ornamental landscape and snow melting, accounting for 78.0% of the total reclaimed water consumption. The experience and methods of Japan in the statistics, collection and classification of the information on wastewater water treatment and reclaimed water utilization can provide important references for standardized management and development of reclaimed water utilization in China.
The situation of water resources, water supply and use, sewage treatment and recycling in Japan were systematically summarized and analyzed. Overall, the whole country of Japan has relatively adequate water, but some areas, like the Kanto coast, Kitakyushu and the East Sea, are short of water. The combined annual per capita water consumption of Japan remains stable at around 630 m3, which is about 1.5 times that of China. The total amount of sewage treatment in Japan is 14.64 billion m3, and the average cost of sewage treatment is 143.3 yen/m3 in 2018. The total amount of reclaimed water utilization in Japan is stable at around 200 million m3 per year, and the utilization rate of reclaimed water is below 1.5%. Large cities, like Tokyo, have a significantly higher utilization rate of centralized reclaimed water of 3.2%, obviously higher than the national average value. Japan uses reclaimed water in a wide range of ways, and the classified statistics of reclaimed water are meticulous and comprehensive, including flushing, landscape environment, snow melting and other nine uses. Reclaimed water is mainly used to supplement surface water, water for ornamental landscape and snow melting, accounting for 78.0% of the total reclaimed water consumption. The experience and methods of Japan in the statistics, collection and classification of the information on wastewater water treatment and reclaimed water utilization can provide important references for standardized management and development of reclaimed water utilization in China.
2023, 41(3): 243-254.
doi: 10.13205/j.hjgc.202303033
Abstract:
Wastewater treatment and reclamation are of great importance for controlling water pollution and alleviating water shortages, which requires efficient treating technologies as the backbone. Membrane-aerated biofilm reactor (MABR) is a novel wastewater treatment technology integrating membrane technology and biofilm technology, which has shown great potential in high-efficiency oxygen mass transfer, as well as the simultaneous removal of organic pollutants and nitrogen contaminants. Therefore, it has been widely studied and applied in wastewater treatment. The mathematical model for MABR is a quantitative description of the system based on mathematical logic language, and is of great significance for in-depth analysis of the essential mechanism and optimization of operating parameters. By reviewing the development history of the MABR mathematical model, two main processes involved in the MABR mathematical model were summarized from the fundamental logic, including the mass transfer model and the reaction model. Furthermore, the key parameters in MABR mathematical model were analyzed based on sensitivity analysis results. The existing problems of MABR model research and the future development trend of the MABR mathematical model, both theoretically and practically were also discussed in the end.
Wastewater treatment and reclamation are of great importance for controlling water pollution and alleviating water shortages, which requires efficient treating technologies as the backbone. Membrane-aerated biofilm reactor (MABR) is a novel wastewater treatment technology integrating membrane technology and biofilm technology, which has shown great potential in high-efficiency oxygen mass transfer, as well as the simultaneous removal of organic pollutants and nitrogen contaminants. Therefore, it has been widely studied and applied in wastewater treatment. The mathematical model for MABR is a quantitative description of the system based on mathematical logic language, and is of great significance for in-depth analysis of the essential mechanism and optimization of operating parameters. By reviewing the development history of the MABR mathematical model, two main processes involved in the MABR mathematical model were summarized from the fundamental logic, including the mass transfer model and the reaction model. Furthermore, the key parameters in MABR mathematical model were analyzed based on sensitivity analysis results. The existing problems of MABR model research and the future development trend of the MABR mathematical model, both theoretically and practically were also discussed in the end.
