Lead-zinc sulphide ore contains lead sulphide (galena), and zinc sulphide (sphalerite). In the first flotation stage, galena is rendered hydrophobic with an organic collector such as xanthate, while sphalerite is kept...Lead-zinc sulphide ore contains lead sulphide (galena), and zinc sulphide (sphalerite). In the first flotation stage, galena is rendered hydrophobic with an organic collector such as xanthate, while sphalerite is kept from floating by depressants, and in the second flotation stage, activator was used to activated zinc flotation. Since the organic regent used are different in the two flotation stage, wastewater from the second zinc flotation stage can’t be directly recycled to the first lead flotation stage. Wastewater from flotation process for concentrating lead-zinc sulphide ore often containing organic compounds such as diethyldithiocarbamate(DDTC), xanthate, terpenic oil(2# oil) and thionocarbamate esters (Z-200), are environmentally hazardous. Their removal from contaminated water and the reuse of the water is one of the main challenges facing lead-zinc sulphide ore processing plants. In this study, synthetic wastewater containing DDTC, xanthate, 2# oil and Z-200 at concentrations ranging from 21 to 42 mg/L was fed into an Ozone/Biological activated carbon (BAC) reactor. Analyses of the effluent indicated a chemical oxygen demand (COD) removal over 86.21% and Total organic carbon (TOC) removal over 90.00% were achieved under Hydraulic retention time (HRT) of 4h and O3 feeding concentration of 33.3mg/L. The effluent was further recycled to the lab scale lead concentrating process and no significant difference was found in compare with fresh water. Furthermore, lead-zinc sulphide mineral concentrating process was carried out at lab scale. The produced wastewater was treated by Ozone/BAC reactor at O3 feeding concentration of 16.7mg/L and HRT of 4h. The effluent analysis showed that TOC removal was 74.58%. This effluent was recycled to the lab scale lead-zinc sulphide mineral concentrating process and the recovery of lead was not affected. The results showed that by using Ozone/BAC technology, the lead-zinc sulphide mineral processing wastewater could be recycled.展开更多
With the 3D chemical transport model OSLO CTM2, the valley of total column ozone over the Tibetan Plateau in summer is reproduced. The results show that when the ozone valley occurs and develops, the transport process...With the 3D chemical transport model OSLO CTM2, the valley of total column ozone over the Tibetan Plateau in summer is reproduced. The results show that when the ozone valley occurs and develops, the transport process plays the main part in the ozone reduction, but the chemical process partly compensates for the transport process. In the dynamic transport process of ozone, the horizontal transport process plays the main part in the ozone reduction in May, but brings about the ozone increase in June and July. The vertical advective process gradually takes the main role in the ozone reduction in June and July. The effect of convective activities rises gradually so that this effect cannot be overlooked in July, as its magnitude is comparable to that of the net changes. The effect of the gaseous chemical process brings about ozone increases which are more than the net changes sometimes, so the chemical effect is also important.展开更多
This study reports an investigation into the degradation of 2,4-dichlorophenoxyacetic acid in bubble contactor column by O2/H2O2 process, which is widely used as a principal advanced oxidation process. The degradation...This study reports an investigation into the degradation of 2,4-dichlorophenoxyacetic acid in bubble contactor column by O2/H2O2 process, which is widely used as a principal advanced oxidation process. The degradation of 2,4-dichlorophenoxyacetic acid was studied under different H202/O3 molar ratio and pH value. Meanwhile, TOC removal was investigated both in distilled water and tap water. The influences of ozone transfer and consumed hydrogen peroxide were also discussed. The degradation products and oxidation intermediates were identified by GC-MS and LC-MS. A possible reaction mechanism was thus proposed.展开更多
Two hybrid processes including ozonation-ceramic membrane-biological activated carbon （BAC） （Process A） and ceramic membrane-BAC （Process B） were compared to treat polluted raw water. The performance of hybrid p...Two hybrid processes including ozonation-ceramic membrane-biological activated carbon （BAC） （Process A） and ceramic membrane-BAC （Process B） were compared to treat polluted raw water. The performance of hybrid processes was evaluated with the removal efficiencies of turbidity, ammonia and organic matter. The results indicated that more than 99% of particle count was removed by both hybrid processes and ozonation had no significant effect on its removal. BAC filtration greatly improved the removal of ammonia. Increasing the dissolved oxygen to 30.0 mg/L could lead to a removal of ammonia with concentrations as high as 7.80 mg/L and 8.69 mg/L for Processes A and B, respectively. The average removal efficiencies of total organic carbon and ultraviolet absorbance at 254 nm （UV254, a parameter indicating organic matter with aromatic structure） were 49% and 52% for Process A, 51% and 48% for Process B, respectively. Some organic matter was oxidized by ozone and this resulted in reduced membrane fouling and increased membrane flux by 25%-30%. However, pre-ozonation altered the components of the raw water and affected the microorganisms in the BAC, which may impact the removals of organic matter and nitrite negatively.展开更多
Beijing faces the challenge of high levels of ozone(O_(3))pollution.In this study,the Weather Research and Forecasting model and Community Multiscale Air Qualitymodel(CMAQ)were used to simulate atmospheric O_(3) conce...Beijing faces the challenge of high levels of ozone(O_(3))pollution.In this study,the Weather Research and Forecasting model and Community Multiscale Air Qualitymodel(CMAQ)were used to simulate atmospheric O_(3) concentrations in Beijing.To investigate the formation mechanisms and source contributions of O_(3) pollution in different regions of Beijing,process analysis and the integrated source apportionmentmethodwithin the CMAQwere applied to O_(3) concentrations in the summer of 2018.The process analysis results showed that vertical diffusion was the major contributor to O_(3) concentrations at all receptor sites in Beijing,at>65.94μg/(m^(3)·hr).Gas-phase chemical reactions consumed a significant amount of O_(3) in urban and inner suburban areas(>−5.57μg/(m^(3)·hr)),while near-surface chemical reactions made positive contributions in outer suburban areas(>4.72μg/(m^(3)·hr)).The O_(3) formation chemical reactions indicated that NO titration,which removes O_(3) at night-time,mainly occurred in urban areas.The weaker chemical reactions occurring near the surface in outer suburbs suggested that suburban-area O_(3) was produced in the upper atmospheric layers and was transported vertically to the lower layers.The O_(3) source apportionment results showed that boundary contributions were the dominant contributor to O_(3) pollution in Beijing(>40%).The contribution of non-local emissions to O_(3) levels was significantly greater in the outer suburbs than in urban and inner suburban areas due to topography.This study increases the understanding of the complex processes of O_(3) formation in different areas of Beijing and informs the implementation of O_(3) control plans.展开更多
As one of the most promising and practical advanced oxidation processes(AOPs),the catalytic ozonation is triggered by the active components of catalyst,which are usually derived from metals or metal oxides.To avoid th...As one of the most promising and practical advanced oxidation processes(AOPs),the catalytic ozonation is triggered by the active components of catalyst,which are usually derived from metals or metal oxides.To avoid the metal pollution from catalyst,here the amorphous boron(A-boron)is used as a metalfree catalyst for catalytic ozonation to produce free radicals for effective degradation of atrazine(ATZ),the world-widely used herbicide and also a widespread pollutant in environment.A-boron exhibits an outstanding performance for catalytic ozonation to remove ATZ from water.As A-boron is introduced into ozonation,the degradation efficiency in 10 min is promoted to 97.1%,much higher than that of 15.1%under ozonation.The mechanism is that the B-B bonds and internal suboxide B in A-boron serve as the main active sites to donate electrons to accelerate ozone decomposition to produce reactive oxygen species(ROS),including·O_(2)^(-)and^(1)O_(2),and further enhance ATZ degradation via ROS reactions.Moreover,the A-boron is still highly active with a degradation efficiency of ATZ over 95%in 10 min even after four successive cycles.This work shows A-boron could be an alternative for the active components of metal or metal oxide in catalytic ozonation.展开更多
Spinning disk reactor(SDR)has emerged as a novel process intensification photocatalytic reactor,and it has higher mass transfer efficiency and photon utilization for the degradation of toxic organic pollutants by adva...Spinning disk reactor(SDR)has emerged as a novel process intensification photocatalytic reactor,and it has higher mass transfer efficiency and photon utilization for the degradation of toxic organic pollutants by advanced oxidation processes(AOPs).In this study,ZnO—TiO_(2)nanocomposites were prepared by solgel method,and coated on the disk of SDR by impregnation-pull-drying-calcination method.The performance of catalyst was characterized by X-ray diffraction,scanning electron microscope,X-ray photoelectron spectroscopy,photoluminescence and ultraviolet—visible diffuse reflectance spectroscopy.Photocatalytic ozonation in SDR was used to remove phenol,and various factors on degradation effect were studied in detail.The results showed that the rate of degradation and mineralization reached 100%and 83.4%under UV light irradiation after 50 min,compared with photocatalysis and ozonation,the removal rate increased by 69.3%and 34.7%,and mineralization rate increased by 56.7%and 62.9%,which indicated that the coupling of photocatalysis and ozonation had a synergistic effect.The radical capture experiments demonstrated that the active species such as photogenerated holes(h^(+)),hydroxyl radicals(·OH),superoxide radical(·O_(2)-)were responsible for phenol degradation,and·OH played a leading role in the degradation process,while h+and·O_(2)^(-)played a non-leading role.展开更多
Indoor air pollutants impact human health,comfort and productivity.The method of photocatalysis has been applied mainly in flow reactors and little information is available on indoor air pollutant removal in airtight ...Indoor air pollutants impact human health,comfort and productivity.The method of photocatalysis has been applied mainly in flow reactors and little information is available on indoor air pollutant removal in airtight reactors.In the paper,experiments were carried out to remove formaldehyde(HCHO),ammonia(NH_3) and volatile organic compounds(VOCs)in the airtight and ventilated chambers.Results demonstrated that 90.4%of HCHO,92.3%of NH_3 and 57.9%of VOCs were removed in the amine adsorption process,while 67.5% (hereinbefore,these are the mass fraction)of HCHO,60.0%of NH_3,and 61.2%of VOCs were removed in the photocatalytic process.However,ozone-assisted photocatalytic process showed great potential to degrade indoor air pollutants in the ventilated chamber.Factors and mechanisms of the photocatalytic degradation of HCHO, NH_3 and VOCs were also discussed.展开更多
To counter the mass reproduction and penetration of crustacean zooplankton in Biological Activated Carbon(BAC)filters which may result in the presence of organisms in potable water and water pollution,this paper analy...To counter the mass reproduction and penetration of crustacean zooplankton in Biological Activated Carbon(BAC)filters which may result in the presence of organisms in potable water and water pollution,this paper analyzed the factors affecting organisms' reproduction in BAC filters.A comparative study was performed on the density and composition of crustacean zooplankton of the concerned water treatment units of two advanced water plants(Plant A and B)which with the same raw water and the same treatment technique in southern China.The results obtained show that the crustaceans' density and composition was very different between the sand filtered water of Plant A and Plant B.which Harpacticoida bred sharply in the sediment tanks and penetrated sand filter into BAC filters was the primary reason of crustaceans reproduce in BAC filters of Plant A.For prevention of the organisms reproduction in BAC,some strengthen measures was taken including pre-chlorination,cleaning coagulation tanks and sediment tanks completely,increasing sludge disposal frequency to stop organisms enter BAC filters,and the finished water quality was improved and enhanced.展开更多
采用Illumina MiSeq高通量测序技术,对臭氧-生物活性炭水处理工艺过程各单元出水中细菌多样性及丰度进行研究,测序获得196 809条16S r DNA基因序列,归类为38个门,522个属。各样品中细菌多样性分析结果表明:在各处理单元出水中细菌群落...采用Illumina MiSeq高通量测序技术,对臭氧-生物活性炭水处理工艺过程各单元出水中细菌多样性及丰度进行研究,测序获得196 809条16S r DNA基因序列,归类为38个门,522个属。各样品中细菌多样性分析结果表明:在各处理单元出水中细菌群落具有高度多样性,预臭氧和臭氧氧化处理对水体中细菌多样性及丰度的影响最大,可杀灭一部分属的细菌,可合理控制臭氧浓度杀灭部分耐氯菌;絮凝沉淀和沙滤单元处理对水体中细菌多样性具有恢复效果,使水体中细菌种属进一步增多;在生物活性炭滤池处理后,细菌多样性增加,丰度分布更为均匀,对后期消毒工艺提出了更高的要求。展开更多
文摘Lead-zinc sulphide ore contains lead sulphide (galena), and zinc sulphide (sphalerite). In the first flotation stage, galena is rendered hydrophobic with an organic collector such as xanthate, while sphalerite is kept from floating by depressants, and in the second flotation stage, activator was used to activated zinc flotation. Since the organic regent used are different in the two flotation stage, wastewater from the second zinc flotation stage can’t be directly recycled to the first lead flotation stage. Wastewater from flotation process for concentrating lead-zinc sulphide ore often containing organic compounds such as diethyldithiocarbamate(DDTC), xanthate, terpenic oil(2# oil) and thionocarbamate esters (Z-200), are environmentally hazardous. Their removal from contaminated water and the reuse of the water is one of the main challenges facing lead-zinc sulphide ore processing plants. In this study, synthetic wastewater containing DDTC, xanthate, 2# oil and Z-200 at concentrations ranging from 21 to 42 mg/L was fed into an Ozone/Biological activated carbon (BAC) reactor. Analyses of the effluent indicated a chemical oxygen demand (COD) removal over 86.21% and Total organic carbon (TOC) removal over 90.00% were achieved under Hydraulic retention time (HRT) of 4h and O3 feeding concentration of 33.3mg/L. The effluent was further recycled to the lab scale lead concentrating process and no significant difference was found in compare with fresh water. Furthermore, lead-zinc sulphide mineral concentrating process was carried out at lab scale. The produced wastewater was treated by Ozone/BAC reactor at O3 feeding concentration of 16.7mg/L and HRT of 4h. The effluent analysis showed that TOC removal was 74.58%. This effluent was recycled to the lab scale lead-zinc sulphide mineral concentrating process and the recovery of lead was not affected. The results showed that by using Ozone/BAC technology, the lead-zinc sulphide mineral processing wastewater could be recycled.
文摘With the 3D chemical transport model OSLO CTM2, the valley of total column ozone over the Tibetan Plateau in summer is reproduced. The results show that when the ozone valley occurs and develops, the transport process plays the main part in the ozone reduction, but the chemical process partly compensates for the transport process. In the dynamic transport process of ozone, the horizontal transport process plays the main part in the ozone reduction in May, but brings about the ozone increase in June and July. The vertical advective process gradually takes the main role in the ozone reduction in June and July. The effect of convective activities rises gradually so that this effect cannot be overlooked in July, as its magnitude is comparable to that of the net changes. The effect of the gaseous chemical process brings about ozone increases which are more than the net changes sometimes, so the chemical effect is also important.
基金The National Natural Science Foundation of China (No. 50378028)
文摘This study reports an investigation into the degradation of 2,4-dichlorophenoxyacetic acid in bubble contactor column by O2/H2O2 process, which is widely used as a principal advanced oxidation process. The degradation of 2,4-dichlorophenoxyacetic acid was studied under different H202/O3 molar ratio and pH value. Meanwhile, TOC removal was investigated both in distilled water and tap water. The influences of ozone transfer and consumed hydrogen peroxide were also discussed. The degradation products and oxidation intermediates were identified by GC-MS and LC-MS. A possible reaction mechanism was thus proposed.
基金supported by the National Grand Water Project(No.2008ZX07423-002)the National Natural Science Foundation of China(No.50978170)the Guangdong Provincial Funding(No.2012B030800001)
文摘Two hybrid processes including ozonation-ceramic membrane-biological activated carbon （BAC） （Process A） and ceramic membrane-BAC （Process B） were compared to treat polluted raw water. The performance of hybrid processes was evaluated with the removal efficiencies of turbidity, ammonia and organic matter. The results indicated that more than 99% of particle count was removed by both hybrid processes and ozonation had no significant effect on its removal. BAC filtration greatly improved the removal of ammonia. Increasing the dissolved oxygen to 30.0 mg/L could lead to a removal of ammonia with concentrations as high as 7.80 mg/L and 8.69 mg/L for Processes A and B, respectively. The average removal efficiencies of total organic carbon and ultraviolet absorbance at 254 nm （UV254, a parameter indicating organic matter with aromatic structure） were 49% and 52% for Process A, 51% and 48% for Process B, respectively. Some organic matter was oxidized by ozone and this resulted in reduced membrane fouling and increased membrane flux by 25%-30%. However, pre-ozonation altered the components of the raw water and affected the microorganisms in the BAC, which may impact the removals of organic matter and nitrite negatively.
基金supported by the National Key Research and Development Program of China(No.2018YFC0213500)the National Key Research and Development Program of China(No.2017YFC0213003).
文摘Beijing faces the challenge of high levels of ozone(O_(3))pollution.In this study,the Weather Research and Forecasting model and Community Multiscale Air Qualitymodel(CMAQ)were used to simulate atmospheric O_(3) concentrations in Beijing.To investigate the formation mechanisms and source contributions of O_(3) pollution in different regions of Beijing,process analysis and the integrated source apportionmentmethodwithin the CMAQwere applied to O_(3) concentrations in the summer of 2018.The process analysis results showed that vertical diffusion was the major contributor to O_(3) concentrations at all receptor sites in Beijing,at>65.94μg/(m^(3)·hr).Gas-phase chemical reactions consumed a significant amount of O_(3) in urban and inner suburban areas(>−5.57μg/(m^(3)·hr)),while near-surface chemical reactions made positive contributions in outer suburban areas(>4.72μg/(m^(3)·hr)).The O_(3) formation chemical reactions indicated that NO titration,which removes O_(3) at night-time,mainly occurred in urban areas.The weaker chemical reactions occurring near the surface in outer suburbs suggested that suburban-area O_(3) was produced in the upper atmospheric layers and was transported vertically to the lower layers.The O_(3) source apportionment results showed that boundary contributions were the dominant contributor to O_(3) pollution in Beijing(>40%).The contribution of non-local emissions to O_(3) levels was significantly greater in the outer suburbs than in urban and inner suburban areas due to topography.This study increases the understanding of the complex processes of O_(3) formation in different areas of Beijing and informs the implementation of O_(3) control plans.
基金Financial support is provided by the Key Research and Development Program of Zhejiang Province(No.2021C03179)the National Key Research and Development Program of China(No.2019YFC0408802)。
文摘As one of the most promising and practical advanced oxidation processes(AOPs),the catalytic ozonation is triggered by the active components of catalyst,which are usually derived from metals or metal oxides.To avoid the metal pollution from catalyst,here the amorphous boron(A-boron)is used as a metalfree catalyst for catalytic ozonation to produce free radicals for effective degradation of atrazine(ATZ),the world-widely used herbicide and also a widespread pollutant in environment.A-boron exhibits an outstanding performance for catalytic ozonation to remove ATZ from water.As A-boron is introduced into ozonation,the degradation efficiency in 10 min is promoted to 97.1%,much higher than that of 15.1%under ozonation.The mechanism is that the B-B bonds and internal suboxide B in A-boron serve as the main active sites to donate electrons to accelerate ozone decomposition to produce reactive oxygen species(ROS),including·O_(2)^(-)and^(1)O_(2),and further enhance ATZ degradation via ROS reactions.Moreover,the A-boron is still highly active with a degradation efficiency of ATZ over 95%in 10 min even after four successive cycles.This work shows A-boron could be an alternative for the active components of metal or metal oxide in catalytic ozonation.
基金supported by the National Natural Science Foundation of China(22208328)Fundamental Research Program of Shanxi Province(20210302124618,202203021212134)。
文摘Spinning disk reactor(SDR)has emerged as a novel process intensification photocatalytic reactor,and it has higher mass transfer efficiency and photon utilization for the degradation of toxic organic pollutants by advanced oxidation processes(AOPs).In this study,ZnO—TiO_(2)nanocomposites were prepared by solgel method,and coated on the disk of SDR by impregnation-pull-drying-calcination method.The performance of catalyst was characterized by X-ray diffraction,scanning electron microscope,X-ray photoelectron spectroscopy,photoluminescence and ultraviolet—visible diffuse reflectance spectroscopy.Photocatalytic ozonation in SDR was used to remove phenol,and various factors on degradation effect were studied in detail.The results showed that the rate of degradation and mineralization reached 100%and 83.4%under UV light irradiation after 50 min,compared with photocatalysis and ozonation,the removal rate increased by 69.3%and 34.7%,and mineralization rate increased by 56.7%and 62.9%,which indicated that the coupling of photocatalysis and ozonation had a synergistic effect.The radical capture experiments demonstrated that the active species such as photogenerated holes(h^(+)),hydroxyl radicals(·OH),superoxide radical(·O_(2)-)were responsible for phenol degradation,and·OH played a leading role in the degradation process,while h+and·O_(2)^(-)played a non-leading role.
基金the National Natural Science Foundation of China(No.21177087)the Shanghai Environmental Protection Bureau(SEPB)Program(No.09-26)
文摘Indoor air pollutants impact human health,comfort and productivity.The method of photocatalysis has been applied mainly in flow reactors and little information is available on indoor air pollutant removal in airtight reactors.In the paper,experiments were carried out to remove formaldehyde(HCHO),ammonia(NH_3) and volatile organic compounds(VOCs)in the airtight and ventilated chambers.Results demonstrated that 90.4%of HCHO,92.3%of NH_3 and 57.9%of VOCs were removed in the amine adsorption process,while 67.5% (hereinbefore,these are the mass fraction)of HCHO,60.0%of NH_3,and 61.2%of VOCs were removed in the photocatalytic process.However,ozone-assisted photocatalytic process showed great potential to degrade indoor air pollutants in the ventilated chamber.Factors and mechanisms of the photocatalytic degradation of HCHO, NH_3 and VOCs were also discussed.
基金Sponsored by the Major National S&T Program-Water Pollution and Governance(Grant No.2009ZX07423-003)
文摘To counter the mass reproduction and penetration of crustacean zooplankton in Biological Activated Carbon(BAC)filters which may result in the presence of organisms in potable water and water pollution,this paper analyzed the factors affecting organisms' reproduction in BAC filters.A comparative study was performed on the density and composition of crustacean zooplankton of the concerned water treatment units of two advanced water plants(Plant A and B)which with the same raw water and the same treatment technique in southern China.The results obtained show that the crustaceans' density and composition was very different between the sand filtered water of Plant A and Plant B.which Harpacticoida bred sharply in the sediment tanks and penetrated sand filter into BAC filters was the primary reason of crustaceans reproduce in BAC filters of Plant A.For prevention of the organisms reproduction in BAC,some strengthen measures was taken including pre-chlorination,cleaning coagulation tanks and sediment tanks completely,increasing sludge disposal frequency to stop organisms enter BAC filters,and the finished water quality was improved and enhanced.
文摘采用Illumina MiSeq高通量测序技术,对臭氧-生物活性炭水处理工艺过程各单元出水中细菌多样性及丰度进行研究,测序获得196 809条16S r DNA基因序列,归类为38个门,522个属。各样品中细菌多样性分析结果表明:在各处理单元出水中细菌群落具有高度多样性,预臭氧和臭氧氧化处理对水体中细菌多样性及丰度的影响最大,可杀灭一部分属的细菌,可合理控制臭氧浓度杀灭部分耐氯菌;絮凝沉淀和沙滤单元处理对水体中细菌多样性具有恢复效果,使水体中细菌种属进一步增多;在生物活性炭滤池处理后,细菌多样性增加,丰度分布更为均匀,对后期消毒工艺提出了更高的要求。
