For the rectangular horizontal-flow sedimentation basin and influent particle- settling characteristics given, calculate the particle removal efficiency. Parameter Flow rate, m3/day 7,570 Length, m 30 Width, m 5 Settling Velocity, m/h Number of Particles, #/mL 0.2 560 0.6 720 1.0 880 1.4 1110 1.81320

For the rectangular horizontal-flow sedimentation basin and influent particle- settling characteristics given, calculate the particle removal efficiency. Parameter Flow rate, m3/day 7,570 Length, m 30 Width, m 5 Settling Velocity, m/h Number of Particles, #/mL 0.2 560 0.6 720 1.0 880 1.4 1110 1.81320

Principles of Geotechnical Engineering (MindTap Course List)

9th Edition

ISBN:9781305970939

Author:Braja M. Das, Khaled Sobhan

Publisher:Braja M. Das, Khaled Sobhan

Chapter2: Origin Of Soil And Grain Size

Section: Chapter Questions

Problem 2.15P: Repeat Problem 2.14 with the following values: Gs = 2.75, temperature of water = 21C, t = 88 min,...

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For the rectangular horizontal-flow sedimentation basin and influent particle- settling characteristics given, calculate the particle removal efficiency. Parameter Flow rate, m3/day 7,570 Length, m 30 Width, m 5 Settling Velocity, m/h Number of Particles, #/mL 0.2 560 0.6 720 1.0 880 1.4 1110 1.81320 3 2.2 1110 2.6 620 3.0 440 3.4 320 3.8 160
A water treatment plant processes 21,000 cubic meters of water per day. Assume two types of flocculated particles enter the basin. You are asked to evaluate the performance of a rectangular sedimentation basin that has dimensions of depth=4 m, width= 6 m, and length= 40 m. The first type of particles has a settling velocity of 0.5 m/hr and the other type has a settling velocity of 1.8 m/hr. What percent of particles are removed for each of the two types of particles?
Please answer all 1. List the three corrections which should be applied to the hydrometer readings. 2. Why is it important to remove the hydrometer from the measuring cylinder between readings? 3. A hydrometer test has the following results; Gs = 2.70, temperature = 240C, and L = 92 mm at 60 minutes after the start of sedimentation. Calculate the diameter of the smallest-size particles that have settled beyond the zone of measurement at that time (use the table in the lab manual to find, A=0.0128). D(mm) = A sqrt( L(cm) / t(min) )
(ii) Consider a primary sedimentation tank (PST) in a water treatment plant with surface overflow rate of 4000 litres/hr/m². What percentage of particles of diameter: (a) 0.05 mm (b) 0.02 mm will be removed in this tank at 20°C? [Assume Stoke's law is valid] Assume at 20°C: Density of water 1000 kg/m³. Density of particle = 2650 kg/m³. g = 9.81 m/s². kinematic viscosity of water (v) = 1.10 × 10-6 m²/s.
Repeat Problem 2.14 with the following values: Gs = 2.75, temperature of water = 21C, t = 88 min, and L = 11.7 cm. 2.14 A hydrometer test has the following result: Gs = 2.65, temperature of water = 26 C, and L = 10.4 cm at 45 minutes after the start of sedimentation (see Figure 2.25). What is the diameter D of the smallest-size particles that have settled beyond the zone of measurement at that time (that is, t = 45 min)? Figure 2.25 ASTM 152H type of hydrometer placed inside the sedimentation cylinder (Courtesy of Khaled Sobhan, Florida Atlantic University, Boca Raton, Florida)
Q1) The data in the table below used to design a sedimentation tank with depth=4m and detention time=2hr, the influent flow is 2000L for each minute. 0.004 0.01 0.02 0.03 0.04 0.05 0.063 0.085 0.12 Settling Velocity(cm/sec) Weight fraction 98 95 Greater than size % 8 6 4 3 2 1 0.5 Determine the overall removal efficiency for this tank, s.g. of particle=1.2 u=0.89x10-³N.s/m². Use Ax=0.1. Q2) For the above question find the depth of sludge for each day if the influent solid concentration is 3000mg/L and percentage of solid=8% and sludge density =1.2 ton/m³.
Еxample A rectangular sedimentation tank with W=25m, L=50m and h=3m. The flow rate = 1500 m/h, and the influent particles concentration = 2000mg/l. The following table shows the percentage of particles as a function of his diameter: Volume of particle (mm) 0.001 10 0.005 20 0.01 15 0.015 15 0.02 20 0.025 20 Find: 1) Settling velocity, if particles density = 2650 kg/ m’ and viscosity of water = 1.002*10*N.s/m? 2) Percentage removal for each particle and total percentage removal 3) Sludge depth, if the tank is cleaned one time per month. If percentage of solide = 8% and sludge density = 1150 kg/ m³ 4) Effluent concentration particles
Q : Discuss the role of different zones in a sedimentation tank with the help of figure Subject : environmental engineering
A batch test on the sedimentation of slurry containing 200kg/m (C.) is carried out experimentally where the initial height of sediment zone is 900mm (h,). The following data are assumed as follows: Underflow concentration= 1200kg/m³ Feed flow rate=3m3/min The relation between setting velocity (u) and height of sediment zone (h:) can be represented by the following equation: u(mm/min)=0.0178*h; - 3.22 Where the h have taken the values: 700,300,260,200 and 180 mm. Graphically, find the critical rate of sedimentation then the cross section area of tank.
A sedimentation basin in a water treatment plant has a length = 50 m, width = 10 m, and depth = 4 m. Particle density = 1.1x10 kg/m'; water density = 10' kg/m2; and dynamic viscosity = 1.307x10-3 N.sec/m2. What is the flow rate, Q, that would remove 70% of particles with a diameter of 0.4 mm?
Determine overall removal obtained for a sedimentation tank having following data: 32.6 m/day Surface overall rate 1 G 1.2 dyanic viscosity 1.027 centipoise Pw 0.997 g/cm³ Particle size 0.1 mm 0.08. m 0.07 mm 0.06 0.04 0.02 0.01 Weight fraction 10% 15% 40% 70% 93% 99% 100% greater in size Use Stoke's law to find out the settling velocity.
4. A water treatment plant has a sedimentation basin with a width of 10.0 m a depth of 3.0 m, a length of 50.0 m, and a flow rate of 4,000 m³/day. a. What is the terminal settling velocity of a particle with a density of 2.4 g/cm³ and a diameter of 0.010 mm in 20°C water? b. What is the percent removal of the particles in part a) for this basin? ( c. What is the smallest diameter particle (mm) with a density of 2.4 g/cm³ that would be removed by this sedimentation basin?