B.E. Environmental Engineering – II-Mumbai-May 2019

MUMBAI UNIVERSITY

Subject:  Environmental Engineering – II

Semester: 6

[Total Time: 3 Hours]
[Total Marks: 80]
N.B: 1) Question No.1 is compulsory.
        2) Attempt any three questions from the remaining five questions.
        3) Assume any suitable data where ever required.
        4) Figures to the right indicate full marks.

Q.1) Attempt any four

a) Differentiate between combined and separate systems of sewerage. (5M)

b) Draw a neat sketch of inverted siphon. (5M)

c) A 3% solution of sewage sample is incubated for 5 days at 20oC. The depletion of oxygen was found to be 3ppm. Determine the BOD of raw sewage. (5M)

d) Define F/M and Sludge age. (5M)

e) Why oil and grease should be removed from wastewater? Draw a neat diagram of a skimming tank. (5M)

Q. 2) a) Describe the procedure for laying and testing of sewers. (10M)

b) State the routine tests carried out in the laboratories at sewage treatment and disposal works and explain the significance of each of them. (10M)

Q. 3) a) What do you understand by the self-purification property of a stream? Explain the factors affecting this property. (10M)

b) Design a high rate single stage trickling filter for treating the following wastewater of a town having a population of 40,000 persons: (10M)
a)Domestic sewage@150 lpcd having 200mg/lit of BOD
b) Industrial wastewater @ 0.25million litres per day having 600mg/lit of BOD. Assume the following:
i)BOD removal in primary clarifier=35%
ii)Permissible organic loading of filter=8000kg/hec-m/day(excluding recirculated sewage)
iii)Recirculation ratio=1.0
iv)Permissible surface loading=160ML/hec/day(including recirculated sewage) Also, Determine the efficiency of the filter.

Q. 4) a) Enumerate the various methods which can be used for disposal of municipal solid waste and explain the two most widely adopted in India. (10M)

b) Differentiate between single pipe and single stack plumbing system with neat sketch. (10M)

Q. 5) a) Explain the working of Activated Sludge Process with neat sketch. Discuss the role of return sludge. (10M)

b) Design the dimensions of a septic tank for the following data: No. of People=150 Sewage/capita/day=130lit Desludging period=2years Length: Width =4:1 (10M)

Q. 6) Write a short note on (any four) (20M)

a) Sludge thickener

b) Oxidation ditch

c) Recycling and reuse of wastewater

d) Constructed wetland

e) Pumping station