In this study, orange G dye was efficiently removed from aqueous solution by ultraflltration （UF） membrane separation enhanced with activated carbon adsorption. The powdered activated carbon （PAC） was deposited on...In this study, orange G dye was efficiently removed from aqueous solution by ultraflltration （UF） membrane separation enhanced with activated carbon adsorption. The powdered activated carbon （PAC） was deposited onto the UF membrane surface, forming an intact filter cake. The enhanced UF process simultaneously exploited the high water permeation flux of porous membrane and the high adsorption ability of PAC toward dye molecules. The influencing factors on the dye removal were investigated. The results indicated that with sufficient PAC incorporation, the formation of intact PAC filtration cake led to nearly complete rejection for dye solution under opti-mized dye concentration and operation pressure, without large sacnticlng the permeation tlux ot the filtration process. Typically, the dye rejection ratio increased from 43.6% for single UF without adsorption to nearly 100% for the enhanced UF process, achieving long time continuous treatment with water permeation flux of 47 L·m^-2·h^-1. The present study demonstrated that adsorption enhanced UF may be a feasible method for the dye wastewater treatment.展开更多
Elemental mercury(Hg0) is predominant constituent of flue gas emitted from coal-fired power plants. Adsorption has been considered the best available technology for removal of Hg0 from flue gas. However, adsorbent inj...Elemental mercury(Hg0) is predominant constituent of flue gas emitted from coal-fired power plants. Adsorption has been considered the best available technology for removal of Hg0 from flue gas. However, adsorbent injection increases the amount of ash generated. In the present study, powdered activated carbon(PAC) was coated on polytetrafluoroethylene/glass fiber filters to increase Hg0 removal while concurrently reducing the amount of ash generated. The optimal PAC coating rate was determined in laboratory experiments to ensure better Hg0 removal with low pressure drop. When PAC of particle size less than 45 μm was used, and the areal density was 50 g/m2, the pressure drop remained under 30 Pa while the Hg0 removal efficiency increased to 15.8% from4.3%. The Hg0 removal efficiency also increased with decrease in filtration velocity. The optimal PAC coating rate was applied on a hybrid filter(HF), which was combined with a bag filter and an electrostatic precipitator in a single chamber. Originally designed to remove fine particulates matter, it was retrofitted to the flue gas control device for simultaneous Hg0 removal. By employing the PAC coating, the Hg removal efficiency of the HF increased to 79.79% from 66.35%. Also, a temporary reduction in Hg removal was seen but this was resolved following a cleaning cycle in which the dust layer was removed.展开更多
Optimizing the characteristics of granular activated carbon(GAC)can improve the performance of biologically activated carbon(BAC)filters,and iodine value has always been the principal index for GAC selection.However,i...Optimizing the characteristics of granular activated carbon(GAC)can improve the performance of biologically activated carbon(BAC)filters,and iodine value has always been the principal index for GAC selection.However,in this study,among three types of GAC treating the same humic acidcontaminated water,one had an iodine value 35%lower than the other two,but the dissolved organic carbon removal efficiency of its BAC was less than 5%away from the others.Iodine value was found to influence the removal of different organic fractions instead of the total removal efficiency.Based on the removal and biological characteristics,two possible mechanisms of organic matter removal during steady-state were suggested.For GAC with poor micropore volume and iodine value,high molecular weight substances(3500–9000 Da)were removed mainly through degradation by microorganisms,and the biodegraded organics(soluble microbial by-products,<3500 Da)were released because of the low adsorption capacity of activated carbon.For GAC with higher micropore volume and iodine value,organics with low molecular weight(<3500 Da)were more easily removed,first being adsorbed by micropores and then biodegraded by the biofilm.The biomass was determined by the pore volume with pore diameters greater than 100μm,but did not correspond to the removal efficiency.Nevertheless,the microbial community structure was coordinate with both the pore structure and the organic removal characteristics.The findings provide a theoretical basis for selecting GAC for the BAC process based on its pore structure.展开更多
基金Supported by Drug Separation and Purification Project in Programme for Development of Novel Drug (2009ZX09301-008)the Program of Introducing Talents of Discipline to Universities (B06006)State Key Laboratory of Precision Measuring Technology and Instruments (Tianjin University)
文摘In this study, orange G dye was efficiently removed from aqueous solution by ultraflltration （UF） membrane separation enhanced with activated carbon adsorption. The powdered activated carbon （PAC） was deposited onto the UF membrane surface, forming an intact filter cake. The enhanced UF process simultaneously exploited the high water permeation flux of porous membrane and the high adsorption ability of PAC toward dye molecules. The influencing factors on the dye removal were investigated. The results indicated that with sufficient PAC incorporation, the formation of intact PAC filtration cake led to nearly complete rejection for dye solution under opti-mized dye concentration and operation pressure, without large sacnticlng the permeation tlux ot the filtration process. Typically, the dye rejection ratio increased from 43.6% for single UF without adsorption to nearly 100% for the enhanced UF process, achieving long time continuous treatment with water permeation flux of 47 L·m^-2·h^-1. The present study demonstrated that adsorption enhanced UF may be a feasible method for the dye wastewater treatment.
基金supported by the Korea Ministry of Environment as "The Eco-Innovation Project" (2013000110002)"The Environmental Health Action Program"(2015001370001)"Knowledge-based Environmental Service (Waste to Energy and Recycling) Human Resource Development Project"
文摘Elemental mercury(Hg0) is predominant constituent of flue gas emitted from coal-fired power plants. Adsorption has been considered the best available technology for removal of Hg0 from flue gas. However, adsorbent injection increases the amount of ash generated. In the present study, powdered activated carbon(PAC) was coated on polytetrafluoroethylene/glass fiber filters to increase Hg0 removal while concurrently reducing the amount of ash generated. The optimal PAC coating rate was determined in laboratory experiments to ensure better Hg0 removal with low pressure drop. When PAC of particle size less than 45 μm was used, and the areal density was 50 g/m2, the pressure drop remained under 30 Pa while the Hg0 removal efficiency increased to 15.8% from4.3%. The Hg0 removal efficiency also increased with decrease in filtration velocity. The optimal PAC coating rate was applied on a hybrid filter(HF), which was combined with a bag filter and an electrostatic precipitator in a single chamber. Originally designed to remove fine particulates matter, it was retrofitted to the flue gas control device for simultaneous Hg0 removal. By employing the PAC coating, the Hg removal efficiency of the HF increased to 79.79% from 66.35%. Also, a temporary reduction in Hg removal was seen but this was resolved following a cleaning cycle in which the dust layer was removed.
基金supported by the National Key R&D Program of China(No.2019YFC0408700)the funds from the National Natural Science Foundation of China(Grant Nos.51778323 and 51761125013)the National Science and Technology Major Projects of China(Nos.2012ZX07404-002,2017ZX07108-002,and 2017ZX07502003).
文摘Optimizing the characteristics of granular activated carbon(GAC)can improve the performance of biologically activated carbon(BAC)filters,and iodine value has always been the principal index for GAC selection.However,in this study,among three types of GAC treating the same humic acidcontaminated water,one had an iodine value 35%lower than the other two,but the dissolved organic carbon removal efficiency of its BAC was less than 5%away from the others.Iodine value was found to influence the removal of different organic fractions instead of the total removal efficiency.Based on the removal and biological characteristics,two possible mechanisms of organic matter removal during steady-state were suggested.For GAC with poor micropore volume and iodine value,high molecular weight substances(3500–9000 Da)were removed mainly through degradation by microorganisms,and the biodegraded organics(soluble microbial by-products,<3500 Da)were released because of the low adsorption capacity of activated carbon.For GAC with higher micropore volume and iodine value,organics with low molecular weight(<3500 Da)were more easily removed,first being adsorbed by micropores and then biodegraded by the biofilm.The biomass was determined by the pore volume with pore diameters greater than 100μm,but did not correspond to the removal efficiency.Nevertheless,the microbial community structure was coordinate with both the pore structure and the organic removal characteristics.The findings provide a theoretical basis for selecting GAC for the BAC process based on its pore structure.
