tailieunhanh - Flocculation In Natural And Engineered Environmental Systems - Chapter 8

Keo tụ trong các hệ thống nước ngọt tự nhiên đã được đề xuất và suy luận của nhiều người Các nhà nghiên cứu,1-4 và điều tra một cách rõ ràng bởi Droppo và Những nghiên cứu này và others6-9 đã kết luận rằng trong quá trình điện hóa, quá trình vi khuẩn cũng đóng một vai trò trong sự hình thành của flocs nước ngọt. Người ta tin (Ongley et ) rằng các quá trình sinh học, góp phần keo tụ trong hai khác nhau cách: liên kết vi khuẩn và vi khuẩn "keo.". | 8 An Example of Modeling Flocculation in a Freshwater Aquatic System Bommanna G. Krishnappan and Jiri Marsalek CONTENTS Introduction. 171 The Stormwater Detention System . 172 Experimental Study. 173 Rotating Circular Flume. 173 Deposition Tests. 174 Mathematical Model. 176 Application of the Model to the Laboratory Data. 178 Input Parameters . 178 Settling Velocity of the Flocs wk. 178 Turbulent Diffusion Coefficient D . 178 Deposition Flux Fd . 179 Erosion Flux Fe . 179 Collision Efficiency Parameter ịì. 179 Collision Frequency Functions Kb Ksh KI Kds. 179 Model for the Growth-Limiting Effect of Turbulence . . . 179 Comparision of Model Predictions with the Measured Data. 180 Summary and Conclusions . 185 Acknowledgments . 186 Nomenclature. 186 References . 187 INTRODUCTION Flocculation in natural freshwater systems has been suggested and inferred by many researchers 1-4 and was explicitly investigated by Droppo and These studies and others6-9 have concluded that in addition to the electrochemical processes the bacterial processes also play a role in the formation of freshwater flocs. It is believed Ongley et that the biological processes contribute for flocculation in two different ways bacterial bonding and bacterial glue. Marshall6 had shown that the 1-56670-615-7 05 2005 byCRC Press 171 Copyright 2005 by CRC Press 172 Flocculation in Natural and Engineered Environmental Systems bacteria have a high affinity for fine grained sediment particles and thereby promotes flocculation by increasing the surface area and bonding two or more mineral particles together. Biddanda11 and Muschenheim et had shown that secretion of extracellular polymeric exudates by certain bacteria provide the necessary bonding material glue to hold particles together. Modeling of the flocculation process in freshwater system has been attempted by several .