In order to obtain mechanically stable membrane for practical application, the imprinted polymer was synthesized in the pores of polyfluoromembrane, the binding and transport ability of the membrane were studied.
Simultaneous nitrification and denitrification （SND） effect and phosphor removal were investigated in a one-staged aerobic submerged membrane bioreactor on pilot-scale with mixed liquor suspended solids （MLSS） 19-...Simultaneous nitrification and denitrification （SND） effect and phosphor removal were investigated in a one-staged aerobic submerged membrane bioreactor on pilot-scale with mixed liquor suspended solids （MLSS） 19--20 g/L. The effects of DO concentration, sludge floc size distribution on SND were studied. Test results suggested that SND was successfully performed in the membrane bioreactor （MBR） and about 70% total nitrogen removal efficiency was achieved when DO concentration was set to 0.2-- 0.3 mg/L. The main mechanisms governing SND were the suitable sludge floc size and the low DO concentration which was caused by low oxygen transfer rate with such a high MLSS concentration in the MBR. In the meantime, phosphor removal was also studied with polymer ferric sulfate （PFS） addition and 14 mg/L dosage of PFS was proper for the MBR to remove phosphor. PFS addition also benefited the MBR operation owing to its reduction of extracellular polymer substances （EPS） of mixed liquor.展开更多
In this study, we modified a polytetrafluoroethylene （PTFE） hollow-fiber membrane element used for submerged membrane bioreactors （MBRs） to reduce the energy consumption during MBR processes. The high mechanical s...In this study, we modified a polytetrafluoroethylene （PTFE） hollow-fiber membrane element used for submerged membrane bioreactors （MBRs） to reduce the energy consumption during MBR processes. The high mechanical strength of the PTFE membrane made it possible to increase the effective length of the membrane fiber from 2 to 3 m. In addition, the packing density was increased by 20% by optimizing the membrane element configuration. These modifications improve the efficiency of membrane cleaning associated with aeration. The target of specific energy consumption was less than 0.4 kWh·m^-3 in this study. The continuous operation of a pilot MBR treating real municipal wastewater revealed that the MBR utilizing the modified membrane element can be stably operated under a specific air demand per membrane surface area （SADm） of 0.13 m^3·m^-2. hr I when the daily- averaged membrane fluxes for the constant flow rate and flow rate fluctuating modes of operation were set to 0,6 and 0.5m^3·m^-2·d^-1 respectively. The specific energy consumption under these operating conditions was estimated to be less than 0.37 kWh.m^-3. These results strongly suggest that operating an MBR equipped with the modified membrane element with a specific energy consumption of less than 0.4 kWh·m^-3 is highly possible.展开更多
Composite fabrics based on Polytetrafluoroethylene(PTFE)polymer displays several notable properties.They are waterproof,windproof,permeable to moisture and thermally insulating at the same time.In the present study,PT...Composite fabrics based on Polytetrafluoroethylene(PTFE)polymer displays several notable properties.They are waterproof,windproof,permeable to moisture and thermally insulating at the same time.In the present study,PTFE fibers are used as raw material to make fiber membranes.The film is formed by crisscrossing interconnected fiber filaments and the related air permeability:tensile creep characteristics and other properties are tested.The results show that the pore size,thickness,and porosity of the film itself can affect the moisture permeability of the film.The water pressure resistance of the selected fabric is 8.5 kPa,and the moisture permeability is 7038 g/(m^(2)·24 h).展开更多
基金The authors thank the National Natural Science Foundation of China(No.29975014)Tianjin Natural Science Foundation(No.003602211)the Doctoral Foundation of Educational Ministry,China(No.20020055002)for financial support.
文摘In order to obtain mechanically stable membrane for practical application, the imprinted polymer was synthesized in the pores of polyfluoromembrane, the binding and transport ability of the membrane were studied.
基金The Hi-Tech Research and Development Program (863) of China (No. 2002AA601220)
文摘Simultaneous nitrification and denitrification （SND） effect and phosphor removal were investigated in a one-staged aerobic submerged membrane bioreactor on pilot-scale with mixed liquor suspended solids （MLSS） 19--20 g/L. The effects of DO concentration, sludge floc size distribution on SND were studied. Test results suggested that SND was successfully performed in the membrane bioreactor （MBR） and about 70% total nitrogen removal efficiency was achieved when DO concentration was set to 0.2-- 0.3 mg/L. The main mechanisms governing SND were the suitable sludge floc size and the low DO concentration which was caused by low oxygen transfer rate with such a high MLSS concentration in the MBR. In the meantime, phosphor removal was also studied with polymer ferric sulfate （PFS） addition and 14 mg/L dosage of PFS was proper for the MBR to remove phosphor. PFS addition also benefited the MBR operation owing to its reduction of extracellular polymer substances （EPS） of mixed liquor.
文摘In this study, we modified a polytetrafluoroethylene （PTFE） hollow-fiber membrane element used for submerged membrane bioreactors （MBRs） to reduce the energy consumption during MBR processes. The high mechanical strength of the PTFE membrane made it possible to increase the effective length of the membrane fiber from 2 to 3 m. In addition, the packing density was increased by 20% by optimizing the membrane element configuration. These modifications improve the efficiency of membrane cleaning associated with aeration. The target of specific energy consumption was less than 0.4 kWh·m^-3 in this study. The continuous operation of a pilot MBR treating real municipal wastewater revealed that the MBR utilizing the modified membrane element can be stably operated under a specific air demand per membrane surface area （SADm） of 0.13 m^3·m^-2. hr I when the daily- averaged membrane fluxes for the constant flow rate and flow rate fluctuating modes of operation were set to 0,6 and 0.5m^3·m^-2·d^-1 respectively. The specific energy consumption under these operating conditions was estimated to be less than 0.37 kWh.m^-3. These results strongly suggest that operating an MBR equipped with the modified membrane element with a specific energy consumption of less than 0.4 kWh·m^-3 is highly possible.
文摘Composite fabrics based on Polytetrafluoroethylene(PTFE)polymer displays several notable properties.They are waterproof,windproof,permeable to moisture and thermally insulating at the same time.In the present study,PTFE fibers are used as raw material to make fiber membranes.The film is formed by crisscrossing interconnected fiber filaments and the related air permeability:tensile creep characteristics and other properties are tested.The results show that the pore size,thickness,and porosity of the film itself can affect the moisture permeability of the film.The water pressure resistance of the selected fabric is 8.5 kPa,and the moisture permeability is 7038 g/(m^(2)·24 h).
