Whether a cationic organic polymer can remove more total cyanide （TCN） than a non-ionic organic polymer during the same flocculation system has not been reported previously. In this study, the effects of organic pol...Whether a cationic organic polymer can remove more total cyanide （TCN） than a non-ionic organic polymer during the same flocculation system has not been reported previously. In this study, the effects of organic polymers with different charge density on the removal mechanisms of TCN in coking wastewater are investigated by polyferric sulfate （PFS） with a cationic organic polymer （PFS-C） or a non-ionic polymer （PFS-N）. The coagulation experiments results show that residual concentrations of TCN （Fe（CN）6^3-） after PFS-C flocculation （TCN 〈 0.2 mg/L） are much lower than that after PFS-N precipitation. This can be attributed to the different TCN removal mechanisms of the individual organic polymers. To investigate the roles of organic polymers, physical and structural characteristics of the floes are analyzed by FT-IR, XPS, TEM and XRD. Owing to the presence of N＋ in PFS-C, Fe（CN）3- and negative flocs （Fe（CN）63- adsorbed on ferric hydroxides） can be removed via charge neutralization and electrostatic patch flocculation by the cationic organic polymer. However, non-ionic N in PFS-N barely reacts with cyanides through sweeping or bridging, which indicates that the non-ionic polymer has little influence on TCN removal.展开更多
Unlike the role of the membrane in a membrane bioreactor, which is designed to replace a sediment tank, direct sewage membrane filtration（DSMF）, with the goal of concentrating organic matters, is proposed as a pretr...Unlike the role of the membrane in a membrane bioreactor, which is designed to replace a sediment tank, direct sewage membrane filtration（DSMF）, with the goal of concentrating organic matters, is proposed as a pretreatment process in a novel sewage treatment concept. The concept of membrane-based pretreatment is proposed to divide raw sewage into a concentrated part retaining most organics and a filtered part with less pollutant remaining, so that energy recovery and water reuse, respectively, could be realized by post-treatment. A pilot-scale experiment was carried out to verify the feasibility of coagulant/adsorbent addition for membrane fouling control, which has been the main issue during this DSMF process. The results showed that continuous coagulant addition successfully slowed down the increase in filtration resistance, with the resistance maintained below 1.0 × 1013m^（-1） in the first 70 hr before a jump occurred. Furthermore,the adsorbent addition contributed to retarding the occurrence of the filtration resistance jump, achieving simultaneous fouling control and chemical oxygen demand（COD）concentration improvement. The final concentrated COD amounted to 7500 mg/L after 6 days of operation.展开更多
基金supported by the National Key Technologies R&D Program of China (No. 2011BAC06B09)the Special Foundation of the President of the Chinese Academy of Sciencesthe National Natural Science Foundation of China (No. 51108441)
文摘Whether a cationic organic polymer can remove more total cyanide （TCN） than a non-ionic organic polymer during the same flocculation system has not been reported previously. In this study, the effects of organic polymers with different charge density on the removal mechanisms of TCN in coking wastewater are investigated by polyferric sulfate （PFS） with a cationic organic polymer （PFS-C） or a non-ionic polymer （PFS-N）. The coagulation experiments results show that residual concentrations of TCN （Fe（CN）6^3-） after PFS-C flocculation （TCN 〈 0.2 mg/L） are much lower than that after PFS-N precipitation. This can be attributed to the different TCN removal mechanisms of the individual organic polymers. To investigate the roles of organic polymers, physical and structural characteristics of the floes are analyzed by FT-IR, XPS, TEM and XRD. Owing to the presence of N＋ in PFS-C, Fe（CN）3- and negative flocs （Fe（CN）63- adsorbed on ferric hydroxides） can be removed via charge neutralization and electrostatic patch flocculation by the cationic organic polymer. However, non-ionic N in PFS-N barely reacts with cyanides through sweeping or bridging, which indicates that the non-ionic polymer has little influence on TCN removal.
基金supported by the Major Science and Technology Program for Water Pollution Control and Treatment of China (No. 2012ZX07205-002)the Tsinghua University Initiative Scientific Research Program (No. 20121087922)the Program for Changjiang Scholars and Innovative Research Team in University (No. IRT1152)
文摘Unlike the role of the membrane in a membrane bioreactor, which is designed to replace a sediment tank, direct sewage membrane filtration（DSMF）, with the goal of concentrating organic matters, is proposed as a pretreatment process in a novel sewage treatment concept. The concept of membrane-based pretreatment is proposed to divide raw sewage into a concentrated part retaining most organics and a filtered part with less pollutant remaining, so that energy recovery and water reuse, respectively, could be realized by post-treatment. A pilot-scale experiment was carried out to verify the feasibility of coagulant/adsorbent addition for membrane fouling control, which has been the main issue during this DSMF process. The results showed that continuous coagulant addition successfully slowed down the increase in filtration resistance, with the resistance maintained below 1.0 × 1013m^（-1） in the first 70 hr before a jump occurred. Furthermore,the adsorbent addition contributed to retarding the occurrence of the filtration resistance jump, achieving simultaneous fouling control and chemical oxygen demand（COD）concentration improvement. The final concentrated COD amounted to 7500 mg/L after 6 days of operation.
