Siderite tailings is a potentially cost-free iron(Fe)source for arsenic(As)fixation in hazardous arsenic-calcium residues(ACR)as stable scorodite.In this study,a pure siderite reagent was employed to investigate the m...Siderite tailings is a potentially cost-free iron(Fe)source for arsenic(As)fixation in hazardous arsenic-calcium residues(ACR)as stable scorodite.In this study,a pure siderite reagent was employed to investigate the mechanism and optimal conditions for As fixation in ACR via scorodite formation,while the waste siderite tailings were used to further demonstrate the cotreatment method.The cotreatment method starts with an introduction of sulfuric acid to the ACR for As extraction and gypsum precipitation,and is followed by the addition of H_(2)O_(2) to oxidize As(Ⅲ)in the extraction solutions and finalized by adding siderite with continuous air injection for scorodite formation.The dissolution-oxidation of siderite can slowly produce Fe(Ⅲ)to control aqueous As(V)-Fe(Ⅲ)precipitation supersaturation for continuous scorodite crystallization.Chemical analyses show that the extraction efficiency of As from the ACR reaches 94.55%,while the precipitation yield of extracted As via scorodite formation arrives at 99.63% and 99.47%,leading to fixation efficiency of 94.20% and 94.04% in terms of the total As in the ACR by using siderite reagent and tailings,respectively.The final solid products show desirable TCLP stability and long-term stability,meeting the requirement for safe storage(GB 5085.3-2007).XRD,FTIR,and TEM results reveal that such high stability is attributable to the formation of scorodite and the surface adsorption of As on the raw siderite and secondary maghemite.This innovative and economical application of siderite tailings for the treatment of hazardous ACR can be extended to the management of hydrometallurgical wastes.展开更多
Passive daytime radiative cooling(PDRC)technology is emerging as one of the most promising solutions to the global problem of spacing cooling,but its practical application is limited due to reduced cooling effectivene...Passive daytime radiative cooling(PDRC)technology is emerging as one of the most promising solutions to the global problem of spacing cooling,but its practical application is limited due to reduced cooling effectiveness caused by daily wear and tear,as well as dirt contamination.To tackle this problem,we report a novel strategy by introducing a renewable armor structure for prolonging the anti-fouling and cooling effectiveness properties of the PDRC coatings.The armor structure is designed by decorating fluorinated hollow glass microspheres(HGM)inside rigid resin composite matrices.The HGM serve triple purposes,including providing isolated cavities for enhanced solar reflectance,reinforcing the matrices to form robust armored structures,and increasing thermal emittance.When the coatings are worn,the HGM on the surface expose their concave cavities with numerous hydrophobic fragments,generating a highly rough surface that guarantee the superhydrophobic function.The coatings show a high sunlight reflectance(0.93)and thermal emittance(0.94)in the long-wave infrared window,leading to a cooling of 5℃ below ambient temperature under high solar flux(∼900 W/m^(2)).When anti-fouling functions are reduced,they can be regenerated more than 100 cycles without compromising the PDRC function by simple wearing treatment.Furthermore,these coatings can be easily prepared using a one-pot spray method with low-cost materials,exhibit strong adhesion to a variety of substrates,and demonstrate exceptional environmental stability.Therefore,we anticipate their immediate application opportunities for spacing cooling.展开更多
With the expanding scale of urban wastewater treatment, the resulting excess sludge quantity is also growing. Excess sludge treatment and disposal has become an important part of the sewage treatment. Sludge itself is...With the expanding scale of urban wastewater treatment, the resulting excess sludge quantity is also growing. Excess sludge treatment and disposal has become an important part of the sewage treatment. Sludge itself is rich in essential nutrients of plant growth such as nitrogen and phosphorus, so it’s a good organic fertilizer;but it often also contains harmful substances such as heavy metals. If the sludge treatment is not good, it not only can bring secondary pollution to the environment, but also can cause the waste of resources. Luminescent bacteria tests are conducted in this research by comparing the effects on the absorption and transformation of toxic substances between traditional sludge drying bed and reed bed. The study finds that the biological toxicity of surface layer sludge either in reed bed or in traditional drying bed has little change with the seasons and maintains in low level. While the biological toxicity in the bottom of sludge has change with the seasons and achieves the lowest level in summer and fall, and the biological toxicity of sludge in reed bed is lower than that of traditional drying bed.展开更多
A new biological nitrogen removal process,which is named herein“The circulating fluidized bed bio-reactor(CFBBR)”,was developed for simultancous removal of nitrogen and organic matter.This process was composed of an...A new biological nitrogen removal process,which is named herein“The circulating fluidized bed bio-reactor(CFBBR)”,was developed for simultancous removal of nitrogen and organic matter.This process was composed of an anaerobic bed(Riser),aerobic bed(Downer)and connecting device.Influent and nitrified liquid from the acrobic bed enters the anaerobic bed from the bottom of the anaerobic bed,completing the removal of nitrogen and organic matter.The system performance under the conditions of different inflow loadings and nitrified liquid recirculation rates ranging from 200% to 600% was examined.From a technical and economic point of view,the optimum nitrifed liquid recirculation rate was 400%.With a shortest total retention time of 2.5 h(0.8 h in the anaerobic bed and 1.5 h in the aerobic bed)and a nitified liquid rocir-culation rate of 400% based on the influent flow rate,the average removal efficiencies of total nitrogen(TN)and sol-uble chemical oxygen demand(SCOD)were found to be 88% and 95%,respectively.The average efluent concentra-tions of TN and SCOD were 3.5 mg/L and 16 mg/L,respoctively.The volatile suspended solid(VSS)concentra-tion,nitrifcation rate and denitrification rate in the system were less than 1.0 g/L,0.0260.1 g NH_(4)^(+)-Ng VSS-d,and 0.016-0.074g NO_(x)^(-)-Ng VSS-d,respectively.展开更多
基金supported by the National Natural Science Foundation of China(Nos.42207258 and 52270150)the Liaoning Provincial Natural Science Foundation Program Project(No.2022-BS-312)+1 种基金the Liaoning University of Technology Doctoral Research Start-up Fund Project(No.XB2021013)the Shenyang Youth Science and Technology Project(No.RC210166).
文摘Siderite tailings is a potentially cost-free iron(Fe)source for arsenic(As)fixation in hazardous arsenic-calcium residues(ACR)as stable scorodite.In this study,a pure siderite reagent was employed to investigate the mechanism and optimal conditions for As fixation in ACR via scorodite formation,while the waste siderite tailings were used to further demonstrate the cotreatment method.The cotreatment method starts with an introduction of sulfuric acid to the ACR for As extraction and gypsum precipitation,and is followed by the addition of H_(2)O_(2) to oxidize As(Ⅲ)in the extraction solutions and finalized by adding siderite with continuous air injection for scorodite formation.The dissolution-oxidation of siderite can slowly produce Fe(Ⅲ)to control aqueous As(V)-Fe(Ⅲ)precipitation supersaturation for continuous scorodite crystallization.Chemical analyses show that the extraction efficiency of As from the ACR reaches 94.55%,while the precipitation yield of extracted As via scorodite formation arrives at 99.63% and 99.47%,leading to fixation efficiency of 94.20% and 94.04% in terms of the total As in the ACR by using siderite reagent and tailings,respectively.The final solid products show desirable TCLP stability and long-term stability,meeting the requirement for safe storage(GB 5085.3-2007).XRD,FTIR,and TEM results reveal that such high stability is attributable to the formation of scorodite and the surface adsorption of As on the raw siderite and secondary maghemite.This innovative and economical application of siderite tailings for the treatment of hazardous ACR can be extended to the management of hydrometallurgical wastes.
基金supported by the National Natural Science Foundation of China(Nos.52003035,52203135 and 51973023)the CHN Energy Group Project(No.GJNY-21-183).
文摘Passive daytime radiative cooling(PDRC)technology is emerging as one of the most promising solutions to the global problem of spacing cooling,but its practical application is limited due to reduced cooling effectiveness caused by daily wear and tear,as well as dirt contamination.To tackle this problem,we report a novel strategy by introducing a renewable armor structure for prolonging the anti-fouling and cooling effectiveness properties of the PDRC coatings.The armor structure is designed by decorating fluorinated hollow glass microspheres(HGM)inside rigid resin composite matrices.The HGM serve triple purposes,including providing isolated cavities for enhanced solar reflectance,reinforcing the matrices to form robust armored structures,and increasing thermal emittance.When the coatings are worn,the HGM on the surface expose their concave cavities with numerous hydrophobic fragments,generating a highly rough surface that guarantee the superhydrophobic function.The coatings show a high sunlight reflectance(0.93)and thermal emittance(0.94)in the long-wave infrared window,leading to a cooling of 5℃ below ambient temperature under high solar flux(∼900 W/m^(2)).When anti-fouling functions are reduced,they can be regenerated more than 100 cycles without compromising the PDRC function by simple wearing treatment.Furthermore,these coatings can be easily prepared using a one-pot spray method with low-cost materials,exhibit strong adhesion to a variety of substrates,and demonstrate exceptional environmental stability.Therefore,we anticipate their immediate application opportunities for spacing cooling.
文摘With the expanding scale of urban wastewater treatment, the resulting excess sludge quantity is also growing. Excess sludge treatment and disposal has become an important part of the sewage treatment. Sludge itself is rich in essential nutrients of plant growth such as nitrogen and phosphorus, so it’s a good organic fertilizer;but it often also contains harmful substances such as heavy metals. If the sludge treatment is not good, it not only can bring secondary pollution to the environment, but also can cause the waste of resources. Luminescent bacteria tests are conducted in this research by comparing the effects on the absorption and transformation of toxic substances between traditional sludge drying bed and reed bed. The study finds that the biological toxicity of surface layer sludge either in reed bed or in traditional drying bed has little change with the seasons and maintains in low level. While the biological toxicity in the bottom of sludge has change with the seasons and achieves the lowest level in summer and fall, and the biological toxicity of sludge in reed bed is lower than that of traditional drying bed.
基金This work was supported by the Key Project of Chinese Ministry of Education(No.205198).
文摘A new biological nitrogen removal process,which is named herein“The circulating fluidized bed bio-reactor(CFBBR)”,was developed for simultancous removal of nitrogen and organic matter.This process was composed of an anaerobic bed(Riser),aerobic bed(Downer)and connecting device.Influent and nitrified liquid from the acrobic bed enters the anaerobic bed from the bottom of the anaerobic bed,completing the removal of nitrogen and organic matter.The system performance under the conditions of different inflow loadings and nitrified liquid recirculation rates ranging from 200% to 600% was examined.From a technical and economic point of view,the optimum nitrifed liquid recirculation rate was 400%.With a shortest total retention time of 2.5 h(0.8 h in the anaerobic bed and 1.5 h in the aerobic bed)and a nitified liquid rocir-culation rate of 400% based on the influent flow rate,the average removal efficiencies of total nitrogen(TN)and sol-uble chemical oxygen demand(SCOD)were found to be 88% and 95%,respectively.The average efluent concentra-tions of TN and SCOD were 3.5 mg/L and 16 mg/L,respoctively.The volatile suspended solid(VSS)concentra-tion,nitrifcation rate and denitrification rate in the system were less than 1.0 g/L,0.0260.1 g NH_(4)^(+)-Ng VSS-d,and 0.016-0.074g NO_(x)^(-)-Ng VSS-d,respectively.
