A rectangular settling tank is to treat 3.6MLD of raw water. The sedimentation period is to be 3 hours; the velocity of flow is 10 cm/min. The cross sectional area of the basin (in m², round off to the nearest integer) is

Unit operations questions

A primary clarifier is to be designed to treat a municipal wastewater. The influent to the clarifier has a flow rate of 7570 m³/d and a total suspended solids concentration of 320 mg/L. A laboratory settling test was performed with the following results: Suspended Solids Concentration (mg/L) at Given Depths Sampling Depth (m) Time (min) 0.61 1.22 246 2.44 272 243 1.83 3.05 10 230 262 282 20 157 195 230 253 30 115 160 211 221 230 45 90 134 163 179 195 60 48 102 131 154 170 90 29 58 86 115 141 (a) Determine the design overflow rate and detention time assuming 65% of the suspended solids are to be removed. Use typical scaling/safety factors as appropriate. (b) Determine the required diameter (to the nearest 0.1 m) and the required depth (to the nearest 0.01 m) for the clarifier.

Q1 Data obtained from a laboratory consolidation test are tabulated as follows: Test points I 2 3 4 5 o' (kPa) Total AH (mm) 20 50 100 0.23 0.87 L.90 3.62 5.55 7.25 200 400 800 G,=2.70, Ho= (initial thickness at zero pressure) = 22.5 mm, w = (moisture content at the beginning of the test) = 0.78. Plot the e-logo' curve and calculate Ce Ae I+eo Ho log a - logo, log(o /06) ΔΗ Hint: and

2. Determine the efficiency of removing particles of size 50 μm and density 1,100 kg/m², settling in a horizontal sedimentation tank of depth 2m, length 10 m and length to width ratio of 3:1. The flow into the sedimentation tank is 2000 m³/d. The dynamic viscosity (u) can be taken as 1.002 x 10* Pa.S.

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.

You are trying to remove 10.0 μm diameter particles in a water treatment plant, so you design a settling basin. The water is at 20 ̊C (giving a water density of 998.2 kg/m3, but really you can assume 1000 kg/m3 here), and the particle density is 1.2 g/mL. The plant treats 0.100 m3/s of water. It is proposed to use a 3.5 m deep, rectangular sedimentation tank with a length to width ration of 5:1. What is the minimum required width of the basin?

Design a sedimentation basin for a water treatment plant with the following specifications assuming it is required to supply a city with a population of 50,000 people: Rectangular or square basin • Depth: 7-18 ft ● . • Width: 10-50 ft Detention time: 4-8 hours Flow through velocity: <0.55 ft/min Overflow rate: 400-1,100 gal/day-ft² Draw a figure to show calculated dimensions. You may consider to use SI units in calculations. ● ● Hint: Overflow rate is Flow/Surface Area; Detention time is Volume of tank/Flow rate; and Depth= Volume/Surface area

A modified Proctor compaction test was carried out using a cylindrical moldwith a 1000 ml volume. Table 2 summarizes the results. a. Plot the compaction and ZAV curves (RD=2.75 and ρwater=1000 kg/m3)b. Determine the maximum dry density and the optimum moisture content    Table 2 Moisture Content (%)Mass of WetSample (g)10.5      2033.211.8      2146.613.0      2203.514.9      2183.116.4       2147.617.6      2116.8