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Chen Y.,Zhenjiang Water Supply Company
Huazhong Keji Daxue Xuebao (Ziran Kexue Ban)/Journal of Huazhong University of Science and Technology (Natural Science Edition) | Year: 2015

In order to improve the utilization and productivity of rapid filter, an innovative solution was proposed to add weir plate in the water channel of rapid filter, which located in Zhenjiang Jinxi water purification plant. Using the proposed level method, the experiment orthogonal table L9(34) was designed. Three factors, which contained the weir plate height, width and length away from the first inlet were selected and each factor was took three levels to design nine types of weir plates. According to homogeneous model and free surface model and k-ω SST model, the free surface flow of aqueduct, transitional section and water channel of rapid filter was numerically simulated. Then making the uniform flow distribution as the optimization target, the optimized set of parameters were obtained. Experimental results show that the flow rate of the No.1 filter tank increases 16.5%. Each filter tank flow rate distributes more evenly and its maximum difference is only 1.4% among them. The results of adding weir plate are significantly and it also proves that homogeneous model is reliable using in the area of water plant or other water conservancy projects. ©, 2015, Huazhong University of Science and Technology. All right reserved.


Yang Z.,Nanjing University of Science and Technology | Shang Y.,Zhenjiang Water Supply Company | Lu Y.,Nanjing University of Science and Technology | Chen Y.,Zhenjiang Water Supply Company | And 7 more authors.
Chemical Engineering Journal | Year: 2011

In this study, a kind of amphoteric chitosan-based flocculants (3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CTA) modified carboxymethyl chitosan, denoted as CMC-CTA) have been prepared. The amphoteric flocculants showed notable improvement in solubility and salt-resistance in the whole pH range compared with its precursors, i.e., chitosan and cationic chitosan. The flocculation properties of CMC-CTA were systematically studied at both the laboratory and pilot scales. At laboratory scale, kaolin suspension was employed as synthetic water in the beaker experiment. The effects of pH, temperature, and original turbidity of untreated water on the dosage and flocculation performances were investigated, respectively. At pH below and above the isoelectric point of CMC-CTA, the optimal flocculation performances were obtained with a dosage of 0.03-0.20. mg/L and 0.8-1.0. mg/L, respectively. The flocculation mechanism was discussed in detail from the morphologies of polymeric flocculants and flocculation kinetics: The shape and charge of polymer chains in the solution greatly influenced the final flocculation performances; The flocculation kinetics agreed well with the particle collision model. Moreover, raw water from the Zhenjiang part of the Yangtze River in China was used for the further investigation of the flocculation properties at the pilot scale. The influences of dosage, sedimentation time, and mechanical mixing rate to the flocculation properties were studied by orthogonal testing. The optimal experimental condition was then obtained. Compared with the currently used flocculants in the Zhenjiang Water Factory, i.e., polyferric sulfate, which has an optimal dosage around 40. mg/L, the value of CMC-CTA (1.1. mg/L) decreased greatly. Above all, the flocculation experiments at the laboratory and pilot scales both indicate that the amphoteric chitosan-based flocculants have good flocculation performances in a wide pH range. © 2011 Elsevier B.V.


Yuan B.,Nanjing University | Shang Y.,Zhenjiang Water Supply Company | Lu Y.,Nanjing University | Qin Z.,Zhenjiang Water Supply Company | And 6 more authors.
Journal of Applied Polymer Science | Year: 2010

A series of chitosan-graft-polyacrylamide copolymers have been prepared as flocculants for waste water treatment. The results indicated that the grafting ratio was one of the key factors for the flocculating effects. The copolymers with various grafting ratios showed different flocculating properties. To observe every detail of this effect, the specific refractive index increment measurement (SRIIM) method was used to determine the grafting ratio at the beginning of this study. Interestingly, it was found that as the grafting ratio increased, the flocculating effect increased until it reached its maximum point. At that point, it decreased. This result was discussed in terms of the cooperative effects of the charge neutralization and bridging flocculating mechanisms. A structure model of chitosan-g-polyacrylamide copolymer flocculants has been proposed. © 2010 Wiley Periodicals, Inc.


Zhang W.,Nanjing University | Shang Y.,Zhenjiang Water Supply Company | Yuan B.,Nanjing University | Jiang Y.,Zhenjiang Water Supply Company | And 6 more authors.
Journal of Applied Polymer Science | Year: 2010

In this study, the flocculating properties of chitosan-graft-polyacrylamide (PAM) copolymer flocculants have been investigated in pilot scale, and the raw water from Zhenjiang part of Yangtse river in China was used as simulated waste water. The influences of dose, mechanical mixing rate, and sedimentation time to the flocculating effects have been investigated in different seasons: summer and winter, respectively. The optimal experimental conditions have been studied by orthogonal test. In addition, the structure effects of the flocculants: the grafting ratio, on the flocculating properties have been also investigated in pilot scale, which results were fully consistent to those from the beaker experiment in laboratory scale using kaolin suspension as simulated waste water. Compared to poly ferric sulfate, current used flocculants in Jinxi Water Factory, chitosan-g-PAM copolymer flocculants showed better flocculating properties, which was ascribed to the cooperative effects of the charge neutralization and bridging flocculating mechanisms of polymer flocculants. © 2010 Wiley Periodicals, Inc.


Yang Z.,Nanjing University | Shang Y.,Zhenjiang Water Supply Company | Huang X.,Nanjing University | Chen Y.,Zhenjiang Water Supply Company | And 7 more authors.
Journal of Environmental Sciences (China) | Year: 2012

A series of biodegradable amphoteric chitosan-based flocculants (3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CTA) modified carboxymethyl chitosan, denoted as CMC-CTA) with different substitution degrees of CTA were prepared successfully. The content of carboxymethyl groups in each CMC-CTA sample was kept almost constant. The solubility of the various flocculants showed that, higher cationic content of flocculants caused a better solubility. The flocculation experiments using kaolin suspension as synthetic water at the laboratory scale indicated that the substitution degree of CTA was one of the key factors for the flocculation properties. With the increase of cationic content, the flocculants were demonstrated better flocculation performance and lower dosage requirement. Flocculation kinetics model of particles collisions combining zeta potential and turbidity measurements was employed to investigate the effects of the cationic content of the flocculants on the flocculation properties from the viewpoint of flocculation mechanism in detail. Furthermore, flocculation performance using raw water from Zhenjiang part of Yangtze River at the pilot scale showed the similar effects to those at the laboratory scale. © 2012 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences.

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