Waste water treatment

Set I

1.

(a) Explain the factors affecting dry weather flow and the effects of flow variations on the design of sewerage system.

(b) Explain the need for sanitation along with different sewerage systems.

Q.2 (a) Define sewer appurtenances. With neat sketch explain the construction and working of manhole and catch basin. 

(b) Explain the process of laying and testing of sewers

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Q.3 (a) Design a sewer to serve a population of 36,000, the daily per capita water supply allowance being 135 litres,of which 80%, find its way into the sewer. The slope available for the sewer to be laid is 1 in 625 and the sewer should be designed to carry four times the dry weather flow, when running full. What would be the velocity of flow in the sewer when running full?

(b) Explain the factors to be considered while selecting the sewer material. What are the commonly used sewer materials?

Q.4 (a) Draw a neat flow diagram employed in Municipal wastewater treatment plant. 06

(b) The 5 day BOD at 30o C of a sewage sample is 120mg/L. Calculate 5 days BOD at 20oC. Assume deoxygenation constant at 20oC, K = 0.1/day. 06

(c) Explain: a) Self cleansing velocity and b) Non scouring velocity. 08

Q.5 (a) Explain the importance of screens and types of screens in the sewage treatment process. 10

(b) Write short notes on: a) Sewage sickness and b) Sewage farming

Q.6 (a) Discuss in detail the process of Deoxygenation and Reoxygenation with respect to selfpurification of Natural water with a neat sketch. 10

(b) A stream, saturated with D O, has a flow of 1.2 m3 /sec, BOD of 4 mg/L and rate constant of 0.3 per day. It receives an effluent discharge of 0.25m3 /sec having BOD of 20 mg/L, D O 5 mg/L and rate constant 0.13 per day. The average velocity of flow of the stream is 0.18m/sec. Calculate the D O deficit at point 20 kms and 40kms downstream. Assume the temperature as 20oC, throughout the BOD is measured at 5 days. Take saturation D O at 20oC as 9.17 mg/L

Q.7 (a) Explain the working of conventional activated sludge process (ASP) with flow diagram 10

(b) Design a primary sedimentation tank of circular cross-section, for a sewage of 10 MLD, detention period of 2 hours and assume the surface loading rate to be 30 m3 /m2 /d

Q.8 (a) Explain briefly the different stages of sludge digestion process in a “Digestor”. With a neat sketch, explain the constructional details of sludge digestion tank. 10

(b) Determine the size of the High rate trickling filters for the following data: i) sewage flow = 4.5 MLD ii) Recirculation ratio = 1.5 iii) BOD of Raw sewage = 250 mg/L iv) BOD removal in primary tank = 30% v) Final effluent BOD desired = 30 mg/L

Q.9 (a) What do you understand by advanced wastewater treatment? How is it different from the conventional treatment? Give, in a tabular form, important AWT processes. 10

(b) Draw a neat sketch of septic tank with soak pit, Write the design criteria required for septic tank.

Q.10 (a) Discuss in brief the biological and chemical methods of removal of phosphorous from wastewater. 10

(b) Write a short note on: a) eco toilet. b) two pit latrines.

 

Set II

1 a. Differentiate between Domestic waste water and industrial waste water.

b. Explain types of sampling.

c. Explain effluent and stream standard with examples

2 a. Explain different zones of pollution in streams

b. A town discharges 80 cumecs of sewage into a stream naving a rate of flow of 1200 cumecs during lean days, at a 5-day BOD of sewage at the given temperature is 250mg/t. Find the amount of critical Dissolved oxygen deficit and its location in the downstream portion of the stream. Assume deoxygenation coefficient K as 0.1 and coefficient of self purification as 3.5. Assume saturated D.O at given temperature as 9.2 mg/?

3 a. Explain methods used for Neutralization of Acidic and Alkaline wastes.

b Explain any two method used for Removal of suspended solids.

4. List the methods used for sludge disposal. Explain any two methods briefly. c. Write short notes on i) Reverse osmosis ii) lon exchange.

5. What are the advantages and disadvantages of combined treatment of industrial waste water with municipal waste water? b. With a flow diagram, explain the units used for treatment of cotton textile mill waste.

6. a. Explain the treatment options for Distillery waste water in India. b. Explain the sources and characteristics of tannery waste.

7. Explain with a flow diagram, treatment option for Sugar Mill Waste.

Explain How pharmaceutical wastes is treated.

Explain with a flow diagram the treatment of paper and pulp mill waste.

Discuss effect of Dairy waste on receiving stream.