ABSTRACT
The project done was the modification of model sedimentation tank. The equipment was made of maslte metal of 16 gauges thickness. Two valves was connected, one for water inlet and the others for water out let at the bottom of the tank. Pumping machine was connected fro pumping in of water into the system. Evolutional test which entails the testing of the constructional work in order to know whether the component needs any adjustment was also carried out. The maintenance procedure is written in the book to avoid constant failure during experimentation. At the end of the test of the modification work, it was seen that the machine is very useful to student for their laboratory experiment based on sedimentation process. The amount of experience gained and the understanding of students’ problems has therefore been methodology based on the production of this book.
TABLE OF CONTENTS
CHAPTER ONE
Introduction 1
Types of Sedimentation 2
Aim and advantages 6
Application of Sedimentation 6
CHAPTER TWO
Literature review 9
Model sedimentation tank circuit diagram 10
Principle of operation 11
Historical aspect 14
CHAPTER THREE
Constructional procedure 26
CHAPTER FOUR
Cost and Estimation 29
CHAPTER FIVE
Discussion/Conclusion 31
Recommendation 34
Reference 38
CHAPTER ONE
INTRODUCTION
Sedimentation tanks, used on a continuously flowing basis, are widely used in water treatment plants. In general, the solid materials to be removed have very low settling velocities because of the small particle sizes and density differences together with the effects of hindered settling due to particle concentrations.
These low settling velocities means that the continuous flow tanks must have long retention times to allow the particles to settle at the base before dean waters flows out of the system. Thus, the extent of particle removal by settling tanks is governed both by the settling properties of the solids and the flow characteristics in the settling zone. Determination of the hydraulic characteristic by traces injection of the inflow to the tank has proved a valuable technique both in model tanks as well as in industrial units.
The Armfield sedimentation tank has been designed to demostate the principles and operation of traces method to evaluate the overall hydraulic characteristic in particular the residence time distribution with various configurations of baffles is the tank. More over, experiments with the settlin efficiency of fine solids may be undertaken, and compared with model prediction based on the residence time models constructed with tracer results. The differences between ideal and non ideal flow are thus demonstrated. The equipment has relevance to courses in both public health and sanitary engineering, as well as to process engineering studies.
TYPES OF SEDIMENTATION
Sedimentation machines are of different form since it is influenced by the kind of forces acting on the particles in the suspension. Generally, it could be divided into two broad types, centrifugal sedimentation and gravity sedimentation machine which could be operated either through batch sedimentation or continuous sedimentation.
CENTRIFUGAL SEDIMENTATION
In centrifugal sedimentation, separation is achieved by the application of centrifugal force which causes the solid particles in the suspension to migrate through the fluid radically away from the axis of rotation depending on the difference in densities between the particles may be intermittent as in the case of the glass as laboratory centrifuge.
In industrial centrifuges, the rotational speed and the centrifugal force is so much that the liquid surface becomes virtually, cylindrical coaxial with the axis of rotation. This ensures quickest settling of the particles on the walls of centrifuge bowl. The liquid phase discharge is usually continuous, while the sold phase deposited on the surface of the bowl can be removed intermittently either manually or by the action of a cutes knife. The time depends on the density of the particle. If the particles have a lesser density than the liquid, it can be removed from the surface of the liquid with a skimming tube.
GRAVITY SEDIMENTATION
This is also a form of sedimentation is which the machine utilizes only or majorly gravitational force for its operation. This is the principle which the sedimentation study apparatus utilizes. It can operate by hindered settling at incipient sedimentation but with time the settling become laminar.
BATCH SEDIMENTATION
These are the several stages in the settling of flocculated suspension and the different zones formed as sedimentation proceeds. In this operation, the concentration of the solid is high enough that the sedimentation of solid particle is hindered by others in a way that solids at a given level settle at a common velocity.
Initially, at incipient sedimentation, the particles are uniformly dispersed in liquid but as time progresses four zones exists in the system. They are the clear liquid zone, the concentrated zone, the transition region and the settled solid region. Initially the transition region and the settled region are not usually distinct but as time progresses, they appear. But after some minutes/hours the clear liquid zone is very distinct, the sedimentation study apparatus used in the laboratory utilizes thus batch sedimentation process. It enables the engineer to be able to observe the sedimentation process easily so that he could apply the necessary principles in the design of a thickener.
THICKENING
The purpose of thickening a slurry is usually to increase the concentration of a relatively large quantity of suspended solid is a feed stream. The sediment can be of importance or the liquid may be required as the case may be.
CLARIFICATION
This involves the process of getting a relatively clear liquid effluent by the removal of small quantity of suspended particles in a suspension usually flocculates are added to the suspension to assist is coagulation and ease the clarification process which is an aspect sedimentation, the flocs formed tend to hold some liquid is them, but as the weight of the solid balances the compressive force of the flocs the liquid is expelled and the settling stops. The factors which affect rate are liquid and particles densities, fluid viscosity, degree of flocculation and particle size, shape and concentration.
SETTLING TEST
The choice of test method used is settling test depends to some extent upon the temperature of the feed. Its flocculating characteristics, the required supernatant clarity and the e available.
This aspect of sedimentation using the sedimentation tank involves the classical glass test which is used for all feed material that settle without a clearly defined and
APPLICATION OF SEDIMENTATION
Sedimentation has a broad applicability is industrial process. It is usually used to separate solid particles from the effluent suspension. In the sewage treatment process sedimentation is used to separate solid waste from solution.
It is also used in water treatment process in other to remove mineral substances and particulate solids from the water after flocculation and coagulation has been effected.
AIMS OF THE SEDIMENTATION TANK
With far application of sedimentation enumerated above, the importance of a technical know how of the process is deemed necessary. This apparatus helps the student to know the fundamentals of sedimentation applications and principles.
ADVANTAGES OF THE SEDIMENTATION
The apparatus is designed to help student in the field of interest to know how the process is carried out and also to know the principles surrounding the process of sedimentation.
The apparatus also helps the student to know the variable factors affecting the process in practical sense such factors research
From the little knowledge which the student obtains from the elementary process as involved in the apparatus, he is exposed to the problems encountered in the more complex design to thickeners which has a lot of industrial application.&n
| 1 - 5 of 96 Reviews |