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Improving the Testing of Sedimentation Processes Development of a Large Column and Observations of Solid Concentration Using Turbidity Measurements

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Improving the Testing of Sedimentation Processes Development of a Large Column and Observations of Solid Concentration Using Turbidity Measurements Bachelor of Engineering Thesis Improving the testing of sedimentation processes Development of a large column and observations of solid concentration using turbidity measurements Student Name: Johnny GIAN Student Number: 42379993 Course Code: CIVL4580 Supervisor: Dr.-Ing habil. Alexander Scheuermann Submission date: 28 October 2016 A thesis submitted in partial fulfilment of the requirements of the Bachelor of Engineering degree in Civil & Geotechnical Engineering School of Civil Engineering Faculty of Engineering, Architecture and Information Technology Johnny Gian 34 Wana St Sunnybank QLD, 4109 28 October 2016 Dr. Jose L. Torero Head School of Civil Engineering The University of Queensland Queensland 4072 Dear Sir, I hereby submit my thesis titled “Improving the testing of sedimentation processes – Development of a large column test and observations of solid concentration using turbidity measurements” for consideration as partial fulfilment of the Bachelor of Engineering degree. All the work contained within this thesis is my original work except where otherwise acknowledged. I understand that this thesis may be made publicly available and reproduced by The University of Queensland unless a limited term embargo on publication has been negotiated with a sponsor. Yours sincerely Johnny Gian Student ID: 42379993 ABSTRACT Sedimentation is an important natural process with widespread applications in water treatment and dredging. Existing methods used to characterise sedimentation processes are often limited by wall effects of the apparatus or the influence of sampling on settling dynamics. In addition, these methods and apparatuses do not allow for post- sedimentation testing, valuable for determining important geotechnical parameters. This research project adopts a novel approach towards sedimentation testing, investigating correlations of turbidity and dielectric measurements to mixture concentration and their use in characterising settling processes without disturbance. A modular large column apparatus was designed to accommodate a suite of instrumentation along its length. This consisted of two different configurations, with specialised base designs, accommodating compatibility with the slurry consolidometer equipment and allowing for post-sedimentation density profiling and hydraulic conductivity tests. In total, six components of this design were developed, with detailed design drawings produced. To determine the relationship between turbidity measurements and the concentration of a suspension, calibration tests were undertaken using TSD-10 turbidity sensors. Inverse function relationships between these parameters were obtained for four different mixture types. The model column tests were designed to investigate the complementary use of dielectric and turbidity correlations in characterising settling processes as a proof-of-concept for the large column design. Findings from these tests indicate that correlating the two sets of measurements provide an improved resolution of concentration data. Additionally, turbidity measurements at low initial mixture concentrations successfully show evidence of hindered settling processes occurring. To continue developing this approach towards sedimentation testing, further design development of the large column is required, followed by fabrication, calibration and experimental testing. Furthermore, additional calibration tests may lead to a better defined relationship between turbidity measurements and concentration, while model column tests using a wider range of initial concentrations and different mixture types should be pursued. i CONTRIBUTIONS BY OTHERS While this report has been completed individually, some calculations have been undertaken and data collected in partnership with Yucheng (Sophia) Jiang, with the generous assistance of Dr. Thierry Bore. The data loggers essential for undertaking the turbidity measurements were kindly provided by Dr. Alistair Grinham. ii ACKNOWLEDGEMENTS Firstly, I would like to thank Alex, my thesis supervisor, for his kindness, patience and encouragement in the undertaking of this project. It would not have been possible if it were not for his clear guidance and timely support. Secondly, I would also like to thank Al for his guidance and advice throughout this project and for providing the data loggers that I desperately needed. I would also like to thank Thierry and Sophia for their work in investigating dielectric correlations and in organising the fabrication of the model column. Thirdly, many thanks go to Sebastian, Jenny and Shayne for their laboratory and workshop assistance. Without their help within apologetically short timeframes, this project would not have been possible. Last but not least, I would like to thank my family and Elaine for supporting me in my studies and in particular, this project. Their support, encouragement and reminders to backup my work were instrumental towards this project’s success. iii TABLE OF CONTENTS Abstract ........................................................................................................................ i Contributions by Others ............................................................................................... ii Acknowledgements ..................................................................................................... iii Table of Contents ....................................................................................................... iv List of Figures ............................................................................................................ vii List of Tables .............................................................................................................. ix Notation ...................................................................................................................... x 1.0 General Introduction ............................................................................................. 1 2.0 Literature Review .................................................................................................. 2 2.1 Sedimentation types ..................................................................................... 2 2.2 Factors influencing settling behaviour .......................................................... 4 2.3 Existing sedimentation testing methods ....................................................... 5 2.4 Summer research project ........................................................................... 10 2.5 Research gaps ........................................................................................... 13 3.0 Project Scope ..................................................................................................... 14 3.1 Research objective ..................................................................................... 14 3.2 Research methodology ............................................................................... 14 3.3 Key project outcomes ................................................................................. 14 3.4 Contents of thesis ....................................................................................... 15 4.0 Large Column Design ......................................................................................... 16 4.1 Design objectives ....................................................................................... 16 4.2 Design considerations ................................................................................ 17 4.2.1 General considerations ................................................................... 17 4.2.2 Consolidometer arrangement .......................................................... 20 4.2.3 Density testing arrangement ........................................................... 24 iv 4.3 Design outcomes ........................................................................................ 25 4.4 Design documentation ................................................................................ 26 5.0 Experimental Testing ........................................................................................... 27 5.1 Calibration Tests ......................................................................................... 27 5.1.1 Aim .................................................................................................. 27 5.1.2 Mixtures ........................................................................................... 27 5.1.3 Equipment ....................................................................................... 27 5.1.4 Variables.......................................................................................... 29 5.1.5 Methodology .................................................................................... 29 5.1.6 Results and discussion .................................................................... 34 5.2 Model Column Tests ................................................................................... 39 5.2.1 Aim .................................................................................................. 39 5.2.2 Column design ................................................................................. 39 5.2.3 Mixtures ........................................................................................... 41 5.2.4 Equipment ....................................................................................... 41 5.2.5 Methodology ...................................................................................
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