Experimental Analysis of Sedimentation Lab 5 Report

User Generated

znepbf5

Engineering

Description

it is a water resources lab report, the lab is about analysis of sedimentation, you need to view the lab manual to understand what the is about, then compute the data, then view requirements and content of the report, files all uploaded

Unformatted Attachment Preview

Lab 5 - Experimental Analysis of Sedimentation: A. Lab Objectives 1. Use settling column experiments to observe and characterize the settling of discrete and flocculent particles under conditions typical of water and wastewater treatment applications. 2. Compare the measured and theoretical settling velocities for the discrete particles examined in the settling column tests. 3. Apply the results from the settling column tests for discrete, flocculent settling to size and design full scale sedimentation tanks for specified flow rates and treatment efficiencies. B. Student Learning Outcomes 1. Describe and compare the 4 classes of sedimentation found in water and wastewater treatment systems. Understand where sedimentation is applied in water and wastewater treatment systems 2. Describe the fluid properties and forces and that influence the sedimentation of a discrete particle in a fluid. Discuss how the Reynolds Number is used to determine laminar or turbulent flow conditions and how it influences the settling velocity of discrete particles. 3. Understand the derivation of terminal settling velocity for a discrete particle. Measure the terminal settling velocity for a variety of particles and compare the measurements to calculated settling velocity based on theory. 4. Understand the relationship between terminal settling velocity and surface loading rate for a sedimentation tank. 5. Compute removal efficiency for a sedimentation tank. 6. Apply results from laboratory settling column studies to the design of sedimentation tanks for flocculent settling (primary sedimentation tanks) and hindered settling (secondary sedimentation tanks). C. References and Reading Tchobanoglous, G., Burton, F.L., and Stensel, H.D. (2003) Wastewater Engineering, Treatment and Resuse/ Metcalf and Eddy, th 4 Edition. McGraw-Hill. pp 361-383. D. Background I. Sedimentation Applications in Water and Wastewater Treatment Systems Sedimentation tanks are applied in several locations in most water and wastewater treatment systems. The sedimentation tanks are designed as plug flow reactors and can have either a rectangular (L/W >3) or a circular surface area. The size of the tanks (depth and surface area) are largely dependent on the flow rate and the nature of the solids that are to be settled and removed. In chemical engineering terms, sedimentation tanks can be viewed as a liquid/solids separation process. Figure 1 shows a line schematic of a typical water treatment system for a source water from a reservoir. The sedimentation tank is placed after the chemicals coagulants are added to the water to help form settle-able solids. Figure 2 shows a schematic of a conventional wastewater system using biological treatment. Sedimentation tanks are used in wastewater systems as grit removal tanks to remove sand-like particles, primary sedimentation tanks to remove settleable organic solids, and secondary sedimentation tanks to remove activated sludge (bacteria and other microorganisms). II. Analysis of Discrete Particle Sedimentation Solids settle in a fluid occur because of the difference in density between the fluid and the solid. When a solid is immersed in a fluid, there are at least two general opposing forces that act on the solid: Eq. 1 Fg = gravitational force = Vp 𝛾 p Eq. 2 Fb = buoyant force = Vf 𝛾𝑓 where Vp = volume of the particle, 𝛾 p = specific weight of the particle, Vf = volume of fluid displaced by the particle, and 𝛾 f = specific weight of the fluid. The buoyancy force (Fb) is the force of the fluid on the solid. If the solid has a greater density than the fluid, the gravitational force overcomes the buoyancy force, causing the solid to move downward, or settle, through the fluid. If the solid has a lower density than the fluid, the buoyancy force overcomes the gravitational force, causing the solid to move upward, or float, toward the surface of the fluid. As the particle begins to move up or down (accelerate) due to the unbalanced gravitational and buoyant forces, another force occurs on the particle – drag forces. Drag forces (Fd) are initially due to the friction of the fluid on the surface of the particle. Drag forces generally cannot be determined from theory, so engineers have used the results of experiments on a variety of shapes to estimate the drag force. The general expression for a drag force is given as: Eq. 3 Fd = Cd A v2/2 where Fd= drag force on the surface of the particle, Cd = coefficient of drag determined from experiments, = density of the fluid, A= cross-sectional area or the projected plan area of the particle in direction of flow, and v = fluid velocity around the particle. When the drag force is added into the force balance, the velocity (v) of the particle will adjust until the sum of Fd, Fb, and Fg equals zero (static equilibrium), at which point the particle will continue to move at a constant velocity (no net force, therefore no acceleration, but velocity is not necessarily zero). The velocity that brings the forces into equilibrium is called the terminal velocity, or terminal settling velocity for the case when the particle is settling through the fluid. An equation (Eq. 4) can be developed for the terminal velocity by rearranging Fb –Fg – Fd = 0. To simplify sedimentation problems, it is common to assume that the particles are spherical in shape, and the Cd values are well documented from experiments using spherical particles (see fig 5-20 p 364 of Metcalf and Eddy, or Fig. 11-5 p 293 of Droste). where vs = terminal settling velocity; p and w = density of particle and water, respectively; d = particle diameter; g = gravitational constant; and Sgp = specific gravity of the particle = 𝜌𝑝 /𝜌𝑤 This all seems very simple, but the problem with applying this equation is that the coefficient of drag (Cd) is also a function of the velocity, as well as the shape and size of the particle. It has been found that the Cd is best described as a function of the Reynolds Number (Nr). Nr is a dimensionless parameter that has been found to be related to the nature of the flow around the particle. where Nr = Reynolds number, = density of fluid, = viscosity of the fluid, v = fluid or particle velocity, and d = diameter of particle. Laminar flow predominates at low values of Nr (Nr 2000), when the velocities tend to be high and the fluid does not move in the distinct streamlines observed in laminar flow. The fluid particles actually move in erratic, or somewhat random, “eddies” as the fluid moves over the particle. There is a transition zone between laminar and fully developed turbulent flow which occurs at Nr values greater than 1 and less than 2000. Values for the fluid properties (𝜌, 𝜇) can be found in reference tables in appendices usually given as a function of temperature. The viscosity is a property of the fluid that describes its resistance to shear. Thick fluids, like molasses, are very viscous. It should also be noted that “d” in Eq. 5 actually represents a characteristic length which varies depending on the nature of the problem. Based on the results of experiments to measure Cd, it was found that for laminar flow conditions: Eq. 6 Cd = 24/Nr ( Nr 2000), the Cd is approximately constant at 0.4, and vs can be computed from Eq. 4. To summarize, the equations given above describe discrete particle settling, which is the simplest case of sedimentation. Discrete particle settling occurs when the particles do not react or combine with each other and when the solids concentrations (number of particles per unit volume of fluid) are relatively low. Although discrete particle sedimentation is the simplest form of sedimentation, it does occur to some extent in sedimentation tanks in both water and wastewater treatment, and in natural systems such as ponds, lakes, and oceans. The most direct application of discrete particle settling is in grit removal chambers which are used in wastewater systems to remove sand-sized particles from the waste stream to protect downstream pumps and equipment. The understanding of discrete particle settling is fundamental to understanding the other classes of sedimentation (flocculent, hindered, and compression sedimentation). Sedimentation tanks are usually designed as plug flow reactors to minimize disturbances in the fluid that would interfere with sedimentation. Most sedimentation tanks are designed so that the water is introduced at the bottom of the tank and is forced to flow upward to exit the tank. The upflow velocity (vu) can be calculated from the continuity equation as: Eq. 9 vu = Q/Asurf where vu = upflow velocity, Q = volumetric flow rate, and Asurf = surface area of the sedimentation tank (L x W for rectangular tanks). The only condition that must be met for a discrete particle to settle is: Eq. 10 vs > vu. If Q and vs are known, the minimum surface area can be calculated by setting vu = vs and rearranging Eq. 9. Hence, vu is an important design and operational parameter in all sedimentation processes, and it is also referred to as the Surface Loading Rate or the Overflow Rate. Note that for discrete particle settling, the depth of the tank does not matter. In fact, an ideal discrete particle sedimentation tank would be a tray (depth = 0). III. Analysis of Flocculent Settling As the particle concentrations increase in a fluid, collisions between particles occur which may result in the formation of larger particles that have higher settling velocities. In addition, certain types of particles may have surface characteristics (such as electrostatic surface charges) that attract other particles and enhance the agglomeration process. The collision and agglomeration process is called flocculation, and the particles that develop are called flocs. Chemicals called coagulants are often added to water prior to sedimentation to enhance the flocculation process. Flocculent settling is more complicated than discrete particle settling because the particle size and settling velocity vary with time as the particle settles. The reactor depth is important in flocculent settling because as the particles settle through the depth of the tank, the chance for flocculation increases which will improve the sedimentation process. There is a limit to the improved settling by flocculation, and this limit occurs when the solids concentration becomes high (usually 1000 mg/L or greater). At the higher solids concentrations, the solids begin to form blanket across the entire settling zone, and the settling velocity becomes “hindered” due to the clogging effect of the solids blanket. So flocculent settling is usually limited to dilute to moderate solids concentrations (100-1000 mg/L) which occur in water treatment systems and in primary sedimentation tanks of wastewater treatment systems. The analysis of flocculent settling must be examined experimentally for each water, and the experimental procedure described below is often used to design sedimentation tanks. Flocculent settling is very important in the design and operation of almost all water and wastewater sedimentation processes. IV. Analysis of Hindered Settling and Compression Settling Hindered settling occurs when the settling flocculent particle concentration becomes high enough to form a distinct sludge interface or blanket between the settling solids and the clarified water. This occurs at solids concentrations generally over 1000 mg/L, and these high concentrations occur in secondary sedimentation tanks of biological wastewater treatment systems. Once the sludge blanket or interface is formed, the settling process becomes very efficient at trapping and removing solids as the blanket passes downward through the water. The particles in the settling blanket all tend to move or settle at the same rate, and because of this, hindered settling is also referred to as “zone” settling. As with flocculent settling, the tank surface area and depth are important for hindered settling, and experimentation is needed for each wastewater to determine the actual settling velocities and solids removal efficiencies. The experimental procedure described below is one of two methods used for the design and analysis of secondary sedimentation tanks. The other method, known as the solids flux approach, can be reviewed from standard references such as Metcalf and Eddy. Compression settling, the fourth class of sedimentation, occurs when the sludge blanket reaches the bottom of the tank, and the particles begin to rest on top of each other. The only additional settling of the sludge blanket occurs when the weight of the particles on top of the blanket compress the solids in the bottom of the blanket. The result is that the solids concentration in the sludge layer becomes higher and more dense, and this process is also referred to as sludge thickening. E. Equipment and Materials Settling columns with depth measurements or a measuring tape Stopwatch Acetate beads of various sizes Beakers Micrometer Thermometer Analytical balance Alum, Soda ash (Na2CO3), and kaolin, beakers and mixers for preparation of flocculent suspension (200-300 mg/L TSS) and sludge (approx. 2000 mg/L TSS). 10L container Turbidimeter (calibrated) and sample cells 4 plastic centrifuge tubes with caps For Total Suspended Solids (TSS) analyses: Glass fiber 1 um or 0.45um filter pads, filter flask and holder, vacuum pump, aluminum weighing dishes, and drying oven (100 C). F. Procedures I. Discrete Particle Settling 1. Prior to the lab, soak the acetate beads in water to remove any trapped air. 2. Fill a settling column with water. Mark the column approximately 1 foot from the top of the column and 1 foot from the bottom of the column. Measure the distance (settling distance) between these two marks. The settling velocity of the discrete particles will be measured between these points. Measure the temperature of the water. 3. Measure the diameter and weight of the (dry) beads (take several measurements to obtain an average, median, and standard deviation). 4. For each different type of particle, gently drop the particle into the water in the settling column. The particle should reach a terminal settling velocity within a short distance from the surface (approx. 1 ft). Use the stopwatch to measure the settling time between the two marks on the settling column (about 1 foot from the top and 1 foot from the bottom of the column). Take several measurements to get a representative average. The settling velocity is then estimated as the settling distance divided by the settling time. II. Flocculent Settling 1. Prior to the experiment, prepare 8 L of a flocculent suspension (approximately 300 mg/L of TSS) prepared from kaolin and alum floc using sodium carbonate for alkalinity based on the following reaction: Al2(SO4)3-18H2O + 3 Na2CO3 + 3 H2O => 2 Al(OH)3(s) + 3Na2SO4 + 3CO2 + 18 H2O a. In a 2 L jar test beaker, add 2 L of tap water and place under a paddle stirrer at 200 rpm for mixing. First weigh and add 1.20 g of kaolin (measure and record the exact weight added). Allow the clay to mix and hydrate for at least 15 minutes. b. After the clay has mixed, weigh and add 2.8 g of soda ash (Na2CO3) to the beaker and continue stirring. After 1 minute of mixing, weigh and add 5.1 g of alum (Al2(SO4)3-18H20) to the beaker. Allow to mix for 1 minute at 200 rpm, and then reduce the mixer speed to about 50-75 rpm to encourage floc formation for about 10- 15 minutes. c. Measure out 6 L of tap water into a container, and pour the prepared 2 L suspension into the container and gently stir to mix thoroughly. Measure the temperature of the water and the turbidity of the mixture. Note: Usually these tests are normally run using TSS measurements instead of turbidity. However, turbidity measurements offer a much faster procedure, and a relationship can be developed between turbidity and TSS for each suspension. d. If desired, a calibration curve can be developed to translate the turbidity measurements into total suspended solids concentration (TSS). Make 4 dilutions of the original suspension (including a full strength sample) and measure the turbidity and TSS of each sample. Plot the results and develop a regression equation to predict TSS as a function of turbidity. 2. After mixing, gently pour the suspension into the settling column up to a height of 5 ft. Stir the contents of the column to obtain a uniform suspension by passing a baffle up and down the column sever times, and immediately start the stop watch after mixing. Withdraw a 20 ml sample from each of the sampling ports using a plastic test tube (centrifuge tube with a screw cap – label the cap on each tube by the port number for each sample). Each sampling port should be identified by its distance (hi) from the water surface in the column. 3. Turn on the portable turbidimeter (the turbidimeter should be calibrated prior to the experiment if necessary). Select a turbidity sample cell and rinse it with DI or tap water. Make sure to shake the centrifuge tube thoroughly prior to pouring the sample into the turbidity cell. Measure and record the turbidity of each sample. At the start, the initial turbidity (and solids concentration) should be the same (or similar) at each port if the contents are uniformly mixed. Use an average of the samples from each port to represent the initial turbidity (it should be similar to the turbidity measured in step 1-d). 4. Observe the column and examine the particles for floc formation and settling. Collect samples every 10 minutes and measure the turbidity for each port until the turbidity levels are near background (usually within 1- 1.5 hours). G. Data Analysis and Discussion Questions I. Discrete Particle Settling 1. Plot the settling velocity vs particle diameter for each type of particle tested. Does the change in settling velocity between particle sizes of the same material vary with the square of the diameter (as would be indicated by Stokes Law)? 2. Compute the Reynolds number for each particle and determine if laminar or turbulent conditions exist. Do these results agree with your answer to question 1? Apply the equations for discrete particle settling to estimate the settling velocity of each sized particle, and compare the calculated velocities to the experimental measurements. II. Flocculent Settling There are two procedures for analyzing the sedimentation data for flocculent settling to design a sedimentation tank to achieve a specified percent removal. The abbreviated method simply measures the average turbidity and percent removal (%R) in the column as a function of time. The traditional detailed method develops iso-removal curves as a function of depth and time in the settling column. Both methods are explained below, but for these labs, the abbreviated method is sufficient. Average Concentration and % Removal Method 1. Calculate the average turbidity through-out the column for each time interval. Next calculate the % Removal (%R) at each time step based on Eq 11: Eq. 11 % Rt = (NTUo - NTUt)/NTUo x 100% where %Rt = percent removal efficiency for the column at time t, NTUo= initial average turbidity of the suspension in the column, and NTUt = average turbidity at time t. 2. Develop a graph of %Rt vs settling time (ts) using results from step 1. Also, the surface loading rate or upflow velocity can be calculated for each time interval from step 4 as H/ts, where H = total water depth and ts= settling time. Generate a graph of %Rt vs surface loading rate (another name for the upflow velocity). These graphs can then be applied to determine the detention time and surface loading rate needed to achieve a specified percent removal. 3. In order to design the full scale sedimentation tank from the experimental data, the required experimental surface loading rate is multiplied by a safety-factor of 0.65- 0.85, and then the required surface area of the tank is determined from Eq.12: Eq. 12 Surface Area (Asurf) = Q/vu where vu is the surface loading rate adjusted for the factor of safety and can be calculated as H/ts. The required depth for the tank is usually taken as the depth of the experimental column multiplied by a safety factor of 1.25-1.50. This safety factor will only affect the surface area of the tank. For a rectangular tank, a L/W ratio of 3/1 (or greater) is recommended to ensure plug flow conditions. Likewise, determine the depth (H) required for the full scale tank based on the detention time required from the settling column tests using Eq 13: \ Eq. 13 td = Volume/Q = Asurf H/Q , or H= td (Q/Asurf) The laboratory detention times are usually multiplied by 1.25-1.50 as a factor of safety for the full scale design. Note that since flocculent sedimentation is dependent on depth, the depth of the tank to be designed is assumed to be at least the same as the depth of the settling column because it is not possible to predict how the suspension would settle at other depths. The safety factor for the detention time provides for larger depths in the full scale sedimentation tank. H. Application Problems (Show your detailed answers in the Appendix) I. Discrete Particle Settling 1. Assuming discrete particle settling with a continuous flow rate of 30 MGD, determine the surface area of the sedimentation tank needed to remove each type of particle by settling as a function of particle diameter. 2. Consider a single bacterial cell as a discrete particle with a diameter of 1x10-6 m and a specific gravity of 1.01. Assuming laminar flow conditions, calculate how long would it take for the cell the settle 1 foot in water at 20 oC? For a flow rate of 4 MGD, what surface area would be required to settle individual cells? Is sedimentation a practical method for removing individual bacterial cells? II. Flocculent Settling 1. Apply the results from your experiment to determine the diameter and depth needed for a full scale sedimentation tank to achieve a 80% removal of the test suspension at a design flow rate of 20 MGD (million gallons per day). 2. Discuss how temperature would affect the settling characteristics. If you were designing a sedimentation tank for flocculent settling, would the summer or winter operating water temperature be the most critical condition (hint: examine how the viscosity of water varies with temperature)? Settling length (ft) = o Temperature of water ( C)= 4 21.2 3 Density of water (kg/m ) = dynamic viscosity (kg/m s) = gravitaional constant (m/s^2)= Particle diameter 1.5 mm 3mm 6 mm Total settling length (m) Weight of particles (g) Number of particles Weight per particle (g) Diameter of particle (m) NR 0.0249 10 0.166 10 1.3921 10 0.00249 0.0166 0.13921 3 Volume of particle (m ) Specific weight (N/m3 ) Specific gravity 1 2 3 Average Exp. Settling Velocity (m/s) Members: 1.5 mm 15.9 15.84 16.09 15.943 Time (sec) 3mm 9.19 9.24 9.07 9.167 6 mm 5.87 5.53 5.60 5.667 Cd Vs (m/s) orange 1.5 mm green 3mm white 6 mm 1. Compute the Reynolds number (NR) for each particle and determine if laminar, transition, or turbulent conditions exist. (base on the temperature, find the viscosity and desity of water ) 2. Find the Cd based on NR 3.Apply the equations for discrete particle settling to estimate 1. Plot the settling velocity (Y-axis) vs particle diameter (X-axis) for each type of particle tested. 2. Compare plots v vs. d; v vs. d2; v vs. d0.5 ch particle and conditions exist. and desity of water ttling to estimate Settling Distance = 5 ft m Turbidity (NTU) of Tap Water Mixture 1 2.38 308 2 2.32 320 Average 2.35 314 1ft Time (min) 0 10 20 30 40 50 60 314.00 83.20 50.70 36.60 25.20 24.80 18.90 Turbidity (NTU) of water at each sampling port 2ft 3ft 4ft 1 2 3 4 Average 314.00 314.00 314.00 314.00 273.00 344.00 319.00 254.80 95.20 172.00 362.00 169.98 38.80 46.30 77.50 49.80 29.40 30.10 31.90 29.15 23.90 24.80 30.70 26.05 20.00 23.30 20.50 20.68 %Rt Vu (m/s) 1. Calculate %R. 2. Plot %R vs settling time (ts) 3. Plot %Rtotal (Y-axis) vs Surface loading rate (X-axis) REPORTS AND PROJECTS REQUIREMENTS A. REPORTS WRITING 1.Lab reports should be written from the perspective of a practicing engineer to the extent possible. The reports should be written for a general technical audience (such as another engineering student or faculty). Assume that the assignments are projects that you are assigned to work on by your project manager or client. Therefore, phrases such as: “the students were given the test specimens ....,” should be avoided. In addition, the stated objectives of the lab should be technical objectives, not “educational objectives.” For instance, a practicing engineer is not likely to tell his client that he did the work to learn how to use the equipment. 2. All reports should be prepared using a Word processor (Microsoft Word) and submitted online. Students will be responsible for maintaining copies of all reports in the event that a file is lost or revisions are necessary. All text should be double spaced. Margins (at least one-inch) should be provided on all sides of the page. Pages should be consecutively numbered beginning with page 1 following the title page. 3.All Tables and Figures must be presented in similar format to the ASCE journals. They should be properly numbered (Figure 1, Table 1), titled, and labeled (including units), and they should appear as soon as possible after they are referred to in the text. 4. For figures (graphs, sketches, pictures, or other illustrations), the figure number and title appear at the bottom of the figure. Table numbers and titles appear at the top of each table. Original data records and sample calculations DO NOT belong in the body of the report, but should be included in titled appendices. The results should be presented in tabular or graphical format, and should include all pertinent data and information to allow the reader to independently check the work. 5. All equations must be sequentially numbered ( ie. Eq. 1 or Equation 1.), and all variables in the equation must be identified the first time they appear in the report. 6.Avoid the use of personal pronouns such as “we” or “I”. Although these pronouns are acceptable and may be preferred in other writing styles, they are not widely accepted by technical journals in engineering. Engineering journals prefer an objective view point ; the work being described should be reproducible by anybody following the procedures described in the study. The use of “we” and “I” is subjective and may imply that only the authors could do the work. 7.Avoid the use of colloquialisms, jargon, and meaningless or unnecessary phrases (ie. -"the results were as expected", or "this was a good experiment”). All parts of the lab report should directly support the objectives of the lab. 8. Use proper spelling and grammar -points will be deducted from lab reports if grammar and spelling errors persist. Help from the University Writing Center should be considered, or may be required, if writing problems are not corrected. References will be made available for help with technical writing. 9.Sections and Content of the Lab Reports: Students should take pride in their lab reports since they represent the work that was put into the lab. A "short report form" will be used for the lab reports for these experiments, and will include the following sections: a. Title Page: b Table of Contents: c. Abstract: a brief one to two-paragraph summaries of the objectives, work conducted during the experiment, and significant results or findings. Sometimes a background statement may be provided at the beginning of the abstract. d. Introduction: Background statement on the relevance of the lab from an engineering perspective; objectives of the lab; overview, or scope, of the work. e. Procedures and Methods: This section consists of two subsections: (1) the experimental procedures performed to acquire the data, and (2) the methods applied to analyze the data to produce the results and achieve the objectives. i. Many students fail to recognize that the equations and statistical methods applied to obtain the results are as important as the raw data. The reader expects to see these methods discussed in this section in order to understand how the objectives of the work were achieved. After reading these details in the Procedures and Methods Section, the reader will know what to look for and expect in the Results and Discussion Section. Students may wish to use subheadings, such as Experimental Procedures and Data Analyses, to help write and organize this section. ii. Provide a general description of the work conducted during the experiment with particular attention to any deviations from the lab manual. Do not provide a step by step set of instructions that are found in the lab manual! Theories, formulas, and equations that are applied to the data, or otherwise examined during the experiment, should be presented and discussed in this section (Data Analyses). Equations should be numbered and all symbols or parameters in the equation should be identified as you would find in a technical journal article. f. Results and Discussion: Tables and graphs should be used to present your data, calculations, and results. Discussion must be provided to describe and explain the data and significance of the information in the tables and graphs. Comparison of results with theory or accepted formulas should be discussed. Sources of error should be discussed with respect to your findings and the significance of these errors with respect to the objectives of the lab g. Conclusions: Summarize objectives, significant results, and discuss conclusions and recommendations. h. References: Provide a bibliographic list of references used in the lab report. I. Appendix Include the original data sheets from lab, calculations (or at least one complete set of well documented sample calculations),application problems, and any other related information which supports the lab report, but does not fit in the main report. All information and data needed to develop the results of the lab or project should be presented either in the main report or the appendix. 10.Check List (in appendix): Students should use the check list to proofread the report and revise the formats, contents of the report if necessary. The check list should be placed in the last page of the report.
Purchase answer to see full attachment
User generated content is uploaded by users for the purposes of learning and should be used following Studypool's honor code & terms of service.

Explanation & Answer

Attached.

1

Sedimentation Lab Report
Institutional Affiliation
Date

2

Table of Contents
Abstract ................................................................................................................................................... 3
Introduction ............................................................................................................................................. 4
Background Statement ........................................................................................................................ 4
Objectives ........................................................................................................................................... 5
Overview ............................................................................................................................................. 5
Procedures and Methods ......................................................................................................................... 5
Equipment and Materials .................................................................................................................... 5
Experimental Procedures .................................................................................................................... 6
Discrete Particle Settling................................................................................................................. 6
Flocculent Settling .......................................................................................................................... 7
Data Analysis ...................................................................................................................................... 7
Discrete Particle Settling................................................................................................................. 7
Flocculent Settling .......................................................................................................................... 9
Application ........................................................................................................................................ 10
Results and Discussion ......................................................................................................................... 11
Discrete Particle Settling................................................................................................................... 11
Tables ............................................................................................................................................ 11
Graphs ........................................................................................................................................... 12
Flocculent Settling ............................................................................................................................ 14
Table ............................................................................................................................................. 14
Graphs ........................................................................................................................................... 15
Discussion ............................................................................................................................................. 16
Discrete Particle Settling................................................................................................................... 16
Flocculent Settling ............................................................................................................................ 17
Conclusions ........................................................................................................................................... 17
References ............................................................................................................................................. 19
Appendix ............................................................................................................................................... 20

3
Abstract
The purpose of this lab was to use settling column experiments to observe and characterize
the settling of discrete and flocculent particles. The theoretical settling velocities were to be
compared with the experimental settling velocities. Results of the experiment were to be
applied in the design of full-scale sedimentation tanks. Settling velocity versus particle
diameter curves were developed for the discrete settling particles. The tests indicated that the
conditions of flow for the three balls sizes were transition and turbulent, and employed
appropriate equations to determine the drag coefficient and velocity of settling. Removal
percentage curves were developed for the flocculent settling based on time and surface
loading. The removal percentage increased with increase in detention time but decreased with
an increase in surface rate load. There was a slight variation between experimental and
theoretical settling variations. This could have resulted from errors due to temperature
variations in the water. The results were applied in the full-scale sedimentation tank design
problems.

4
Introduction
Background Statement
In water and wastewater treatment, several stages of treatment are involved. Sedimentation is
one of the stages ...

Related Tags