The effectiveness of a magnetic ion exchange resin （MIEX） for the treatment of Hongze Lake water in China was evaluated, The kinetics of natural organic matter （NOM） removal at various MIEX doses and contact time,...The effectiveness of a magnetic ion exchange resin （MIEX） for the treatment of Hongze Lake water in China was evaluated, The kinetics of natural organic matter （NOM） removal at various MIEX doses and contact time, multiple-loading experiments, impacts of MIEX prior to coagulation on coagulant demands and the effectiveness of combination of MIEX, pre-chlorination and coagulation were investigated. Kinetic experimental results show that more than 80% UV254 and 67% dissolved organic carbon （DOC） from raw water can be removed by the use of MIEX alone. 94% sulfate, 69% nitrate and 98% bromide removals are obtained after the first use of MIEX in multiple-loading experiments. It is suggested that MIEX can be loaded up to 1 250 bed volume （BV, volume ratio of tested water to resin） or more without saturation when regarding organics removal as a target. MIEX can remove organics to a greater extend than coagulation and lower the coagulant demand when combining with coagulation. Chlorination experimental results show that MIEX can remove 57% chlorine demand and 77% trihalomethane formation potential （THMFP） for raw water. Pre-chlorination followed by MIEX and coagulation can give additional organic and THMFP removals. The results suggest that MIEX provides a new method to solve thc problem algae reproduction.展开更多
Fouling of cellulose triacetate（CTA） forward osmosis（FO） membranes by natural organic matter（NOM） was studied by means of a cross-flow fiat-sheet forward osmosis membrane system. The NOM solution was employed as...Fouling of cellulose triacetate（CTA） forward osmosis（FO） membranes by natural organic matter（NOM） was studied by means of a cross-flow fiat-sheet forward osmosis membrane system. The NOM solution was employed as the feed solution（FS）, and a sodium chloride solution（3 tool/L） was used for the draw solution（DS）. The process was conducted at various temperatures and cross-flow velocities. The flux decline was investigated with 3 h forward osmosis operation. The substances absorbed on the membranes were cleaned by ultrasonic oscillation of the fouled membranes and were characterized by methodologies including fluorescence excitation-emission matrices （EEMs） and liquid chromatography with an organic carbon detector（LC-OCD）, and the variations of membrane properties were also investigated by Fourier transform infrared spectrometer（FTIR） and a contact angle meter. It was noted that the rejection efficiency of NOM is remarkable and that ultrasonic oscillation is an effective method to extract the NOM fouled on the CTA membranes after FO process. A higher cross-flow velocity and lower temperature benefit the anti-fouling capacity of the membrane significantly. Although humic substances accounted for the majority of the NOM, aromatic proteins and amino acids were the main fouling components on the membranes, with symbolic FTIR peaks at 2355, 1408 and 873 cm^-1. The present surface foulant made the membranes becoming more hydrophilic, as demonstrated by a significant decrease in contact angle（ranging from 20% to 46%） under all the operation conditions.展开更多
The source water in one forest region of the Northeast China had very high natural organic matter（NOM） concentration and heavy color during snowmelt period. The efficiency of five combined treatment processes was co...The source water in one forest region of the Northeast China had very high natural organic matter（NOM） concentration and heavy color during snowmelt period. The efficiency of five combined treatment processes was compared to address the high concentration of NOM and the mechanisms were also analyzed. Conventional treatment can hardly remove dissolved organic carbon（DOC） in the source water. KMn O4pre-oxidization could improve the DOC removal to 22.0%. Post activated carbon adsorption improved the DOC removal of conventional treatment to 28.8%. The non-sufficient NOM removal could be attributed to the dominance of large molecular weight organic matters in raw water, which cannot be adsorbed by the micropore upon activated carbon. O3＋ activated carbon treatment are another available technology for eliminating the color and UV254 in water. However, its performance of DOC removal was only 36.4%, which could not satisfy the requirement for organic matter. The limited ozone dosage is not sufficient to mineralize the high concentration of NOM. Magnetic ion-exchange resin combined with conventional treatment could remove 96.2%of color, 96.0% of UV254 and 87.1% of DOC, enabling effluents to meet the drinking water quality standard. The high removal efficiency could be explained by the negative charge on the surface of NOM which benefits the static adsorption of NOM on the anion exchange resin. The results indicated that magnetic ion-exchange resin combined with conventional treatment is the best available technology to remove high concentration of NOM.展开更多
In China surface water pollution has made quality drinking water production difficult. The major pollutants in surface water are organic matter measured by COD Mn and ammonia nitrogen. To remove these pollutants effec...In China surface water pollution has made quality drinking water production difficult. The major pollutants in surface water are organic matter measured by COD Mn and ammonia nitrogen. To remove these pollutants effectively, membrane bioreactor （MBR） was studied as a substitute for the conventional water treatment process. Powdered activated carbon （PAC） was dosed into the reactor to enhance the treatment efficiency. A pilot scale MBR was operated continuously for 130 days. In this period, 79.1% of COD Mn , 85.9% of UV 254 , 97.9% of UV 410 , 99.6% of turbidity and 97.4% of NH3-N could be removed, and the total coli-group was not detectable per 100 ml in the treated water. Concerning the accumulation of refractory organics in the reactor, an index A m （organics accumulative factor in the mixed liquor） was proposed. It helps to evaluate the efficiency of biodegradation and PAC adsorption of organic pollutants in the reactor. Moreover,Am appeared to have a negative effect on the removal efficiency of organic pollutants.At the end of the pilot test, three-step cleanings were carried out for the fouled membrane. The flux recovery for each cleaning step was measured, and the composition of the eluted foulants after each chemical cleaning step was analyzed. The results demonstrated that organic pollutants were the major membrane-fouling substances, and chemical cleaning with 0.4% sodium hypochlorite could remove them efficiently.展开更多
基金Project(2008ZX07421-002) supported by the Key National Science and Technology Project of ChinaProject(50638020) supported by the National Natural Science Foundation of China
文摘The effectiveness of a magnetic ion exchange resin （MIEX） for the treatment of Hongze Lake water in China was evaluated, The kinetics of natural organic matter （NOM） removal at various MIEX doses and contact time, multiple-loading experiments, impacts of MIEX prior to coagulation on coagulant demands and the effectiveness of combination of MIEX, pre-chlorination and coagulation were investigated. Kinetic experimental results show that more than 80% UV254 and 67% dissolved organic carbon （DOC） from raw water can be removed by the use of MIEX alone. 94% sulfate, 69% nitrate and 98% bromide removals are obtained after the first use of MIEX in multiple-loading experiments. It is suggested that MIEX can be loaded up to 1 250 bed volume （BV, volume ratio of tested water to resin） or more without saturation when regarding organics removal as a target. MIEX can remove organics to a greater extend than coagulation and lower the coagulant demand when combining with coagulation. Chlorination experimental results show that MIEX can remove 57% chlorine demand and 77% trihalomethane formation potential （THMFP） for raw water. Pre-chlorination followed by MIEX and coagulation can give additional organic and THMFP removals. The results suggest that MIEX provides a new method to solve thc problem algae reproduction.
基金Supported by the National Natural Science Foundation of China（Nos.51178322, 51378367） and the National Science and Technology Maj or Project, China（Nos.2012ZX07408-001, 2012ZX07404-004）.
文摘Fouling of cellulose triacetate（CTA） forward osmosis（FO） membranes by natural organic matter（NOM） was studied by means of a cross-flow fiat-sheet forward osmosis membrane system. The NOM solution was employed as the feed solution（FS）, and a sodium chloride solution（3 tool/L） was used for the draw solution（DS）. The process was conducted at various temperatures and cross-flow velocities. The flux decline was investigated with 3 h forward osmosis operation. The substances absorbed on the membranes were cleaned by ultrasonic oscillation of the fouled membranes and were characterized by methodologies including fluorescence excitation-emission matrices （EEMs） and liquid chromatography with an organic carbon detector（LC-OCD）, and the variations of membrane properties were also investigated by Fourier transform infrared spectrometer（FTIR） and a contact angle meter. It was noted that the rejection efficiency of NOM is remarkable and that ultrasonic oscillation is an effective method to extract the NOM fouled on the CTA membranes after FO process. A higher cross-flow velocity and lower temperature benefit the anti-fouling capacity of the membrane significantly. Although humic substances accounted for the majority of the NOM, aromatic proteins and amino acids were the main fouling components on the membranes, with symbolic FTIR peaks at 2355, 1408 and 873 cm^-1. The present surface foulant made the membranes becoming more hydrophilic, as demonstrated by a significant decrease in contact angle（ranging from 20% to 46%） under all the operation conditions.
基金supported by the project of " Major Science and Technology Program for Water Pollution Control and Treatment of China " (No. 2008ZX07420-005)the Natural Science Foundation of China (No. 51290284)the Tsinghua University Initiative Scientific Research Program (No. 20131089247)
文摘The source water in one forest region of the Northeast China had very high natural organic matter（NOM） concentration and heavy color during snowmelt period. The efficiency of five combined treatment processes was compared to address the high concentration of NOM and the mechanisms were also analyzed. Conventional treatment can hardly remove dissolved organic carbon（DOC） in the source water. KMn O4pre-oxidization could improve the DOC removal to 22.0%. Post activated carbon adsorption improved the DOC removal of conventional treatment to 28.8%. The non-sufficient NOM removal could be attributed to the dominance of large molecular weight organic matters in raw water, which cannot be adsorbed by the micropore upon activated carbon. O3＋ activated carbon treatment are another available technology for eliminating the color and UV254 in water. However, its performance of DOC removal was only 36.4%, which could not satisfy the requirement for organic matter. The limited ozone dosage is not sufficient to mineralize the high concentration of NOM. Magnetic ion-exchange resin combined with conventional treatment could remove 96.2%of color, 96.0% of UV254 and 87.1% of DOC, enabling effluents to meet the drinking water quality standard. The high removal efficiency could be explained by the negative charge on the surface of NOM which benefits the static adsorption of NOM on the anion exchange resin. The results indicated that magnetic ion-exchange resin combined with conventional treatment is the best available technology to remove high concentration of NOM.
文摘In China surface water pollution has made quality drinking water production difficult. The major pollutants in surface water are organic matter measured by COD Mn and ammonia nitrogen. To remove these pollutants effectively, membrane bioreactor （MBR） was studied as a substitute for the conventional water treatment process. Powdered activated carbon （PAC） was dosed into the reactor to enhance the treatment efficiency. A pilot scale MBR was operated continuously for 130 days. In this period, 79.1% of COD Mn , 85.9% of UV 254 , 97.9% of UV 410 , 99.6% of turbidity and 97.4% of NH3-N could be removed, and the total coli-group was not detectable per 100 ml in the treated water. Concerning the accumulation of refractory organics in the reactor, an index A m （organics accumulative factor in the mixed liquor） was proposed. It helps to evaluate the efficiency of biodegradation and PAC adsorption of organic pollutants in the reactor. Moreover,Am appeared to have a negative effect on the removal efficiency of organic pollutants.At the end of the pilot test, three-step cleanings were carried out for the fouled membrane. The flux recovery for each cleaning step was measured, and the composition of the eluted foulants after each chemical cleaning step was analyzed. The results demonstrated that organic pollutants were the major membrane-fouling substances, and chemical cleaning with 0.4% sodium hypochlorite could remove them efficiently.
