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Seat No.: Enrolment
GUJARAT TECHNOLOGICAL UNIVERSITY
ME SEMESTER-II • EXAMINATION SUMMER 2017
Subject Code: 2721802 Date: 25/05/2017
Subject Name: Treatment Process Design and Drawing
Time: 02:30 PM To 05:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
Q.1

Design a paddle flocculator by determining the basin dimensions, the paddle configuration and the power requirement for the following parameters:
Design Flow Rate= 50x103 m3/d
t 22 minutes
Three flocculator compartments with 40, 30, 20 s-1
(iv)Water temperature 150 C Take μ=1.139x10-3Pa.s
07

A town has been directed to upgrade its primary WWTP to a secondary plant that can meet an effluent standard of 25.0 mg/L BOD5 and 30 mg/L suspended solids. They have selected a completely mixed activated sludge system for the upgrade. The existing primary treatment plant has a flow rate of 2,506 m3/d. The effluent from the primary tank has a BOD5 of 240 mg/L. Using the following assumptions, estimate the required volume of the aeration tank:
1. BOD5 of the effluent suspended solids is 70% of the allowable suspended solids concentration
2. Growth constant values are estimated to be: Ks 100 mg/L BOD5; kd 0.025 d 10 d =0.8 mg VSS/mg BOD5 removed.
3. The design MLVSS is 3,000 mg/L
07
Q.2

A filter with 1200 m2 of surface area is used to clean 11 m3/s of air which has a dust loading of 0.0015 kg/m3.The values of Rf and Rp are 22000 kg/m2s. and 25,000 s-1 respectively If it is desirable for the overall pressure drop not to exceed 2100 determine the maximum allowable cleaning period in hours.
07

An electro static precipitator has six collecting plates 3m tall and 3 m long in the direction of flow. The spacing between the plates is 229 mm. the ESP is to be used to collect particles having a dielectric constant of 4.0 and an effective diameter of 3 mm. The carrier gas (air at 4200 has a throughput velocity of 7.3 m/s. Calculate the voltage required for 99.5% collection efficiency. Assume the strength of charge in field and collecting field strength are same, Neglect Cunningham correction factor. Viscosity at 4200 K is 2.4x 10-5 kg/m.s
07
OR

Design an aerated grit chamber for an average flow of 8 MLD. Check for detention time and surface loading rate.
07
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Q.3

Design following units of Rapid Sand Filter system for the town of 1.2 lakh population. The rate of water supply is 200 capita-day. Take peaking factor of 1.5.Assume necessary data. Design for following:
1. Number of filter beds
2. Depth of sand bed
3. Gravel bed
07

Explain the purpose and location of the following unit operations/processes in water treatment plant
Floculation softening
Aeration Disinfection
Ion exchange Recarbonation
RO
07
OR
Q.3

Sludge drying bed length, breadth and depth dimensions are 15m x 6m x 0.45m. The sludge contains 3.8% solids. Calculate how many Kg solids are there in the sludge drying beds.
07

Calculate the amount of sludge to be handled by the sludge drying beds of size 25m x 5m x 4 nos. sludge depth as normal 0.25m .The sludge contains 2.5 solids and the sludge bed requires 30 days to settle and cleaning for second application. Calculate the amount of sludge applied with the loading rate . Assume specific gravity of sludge as 1.02.
07
Q.4
Design a tube module for rectangular cross section with following data:
Design flow=1.5 MLD
Cross sectional area of tube=50mmx50mm
Length of tube= 1 m
Angle of inclination =600 to horizontal
14
OR
Q.4
Design a fine screen element with chamber for a peak flow of 50 MLD.Flow conditions in incoming trunk sewer is given by
Diameter of sewer=1.5 m
Depth of flow at peak design flow= 1 m
Velocity at peak design flow= 0.8 m/s
Drop of screenchamber flow with respect to sewer invert=0.08 m
Screen efficiency factor=0.56
14
Q.5

A cyclone separator has an inlet width of 0.05 m and Vi= 18m/s. Estimate the cut size diameter for this cyclone and also estimate the collection efficiency of this cyclone separator for particles with 1 in diameter . Assume the following
1.84x10-5 Kg/m s Ne Density of particle=2000 kg/m3 and density of gas=1.185 kg/m3
07

Calculate the solids loading rate for 12 m3 sludge filter press operation with following data
Filter press surface area 40 m2
Solids concentration in sludge 2.5
Filtration time= 110 minutes for 100Kg and feed time is 10 minutes
Specific gravity of sludge =1.01
07
OR
Q.5

Design a venture scrubber with a flow of 2m3/s along with neat sketch.
07
3

Define the following terms along with the design equations: Cut size diameter Saltation velocity Number of effective turns A/C Ratio Cane velocity Efficiency with respect to Venturi scrubber Filter drag
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