JNTU
JNTU B.Tech III Year ENVIRONMENTAL ENGINEERING Previous Question Paper (November/December - 2018 - R16)
Note: This question paper contains two parts A and B. Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit. Each question carries 10 marks and may have a, b, c as sub questions.
PART - A
Why is population forecast necessary in the design of public water supply schemes.
Answer
Population forecasting is essential to estimate the future water demand over the design period (typically 30-50 years). This ensures that water supply infrastructure, such as treatment plants, reservoirs, and distribution mains, is sized correctly to meet the needs of the growing population without becoming inadequate or excessively over-designed.
Define hardness of water. How can it be measured?
Answer
Hardness of water is the property that prevents the formation of lather with soap, caused primarily by the presence of dissolved multivalent metallic cations, mainly calcium (Ca²⁺) and magnesium (Mg²⁺). It is measured in the laboratory using the EDTA titrimetric method, where water is titrated against disodium EDTA using Eriochrome Black T as an indicator at a pH of 10.
Distinguish between slow sand and rapid sand filters.
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Write a note on water carriage system.
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At what point in a pipe system you will provide a single acting and double acting air valve and why?
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Distinguish between gravity conduit and pressure conduit.
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What is the object of flushing tank?
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Under what circumstances we need the placing of inverted syphon?
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Why is it necessary to provide grit chamber in sewage treatment plants for combined sewerage system.
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Write short notes on sludge conditioning.
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PART - B
Explain three different methods of forecasting the future population of a town. Comment on their relative merits.
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Mention the various impurities in water which should be take into account in deciding the potability of water.
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Discuss how the future population of a town is estimated. What are the assumptions made for forecasting the population of a city?
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What are Escherichia coli or E-coli? Are they harmful to human beings? Why is their presence tested in water that is supplied for domestic consumption? Describe briefly the procedure followed in conducting such a test.
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Mention any two coagulants used in water treatment and describe the reactions of these coagulants.
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Describe the method of softening by Zeolite process.
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Design a set of rapid gravity filters for treating water required for a population of 50,000; the rate of supply being 180 litres per head per day. The filters are rated to work at 5200 litres per square metre per day.
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Write briefly on carbonate and non-carbonate hardness in water and their removal.
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A town is receiving its water supply from a reservoir through 90 cm diameter gravity main with a fall of 100 m in 100 km. Due to growth of population it is proposed to increase the supply by 50% laying a part of length an additional 150 cm dia pipe and the new line being cross connected. Find out the length of the new pipe. (Assume friction factor f = 0.01)
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What design criterion is commonly employed for determining the sizes of the gravity mains used for conveying water from high level impounded reservoirs to towns situated at considerable distance away from the town.
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Two 150 mm pipes of equal diameters form a loop in a distribution network. Calculate the diameter of an equivalent of same length to represent the loop (there are no intermediate draw offs).
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Describe briefly the procedure followed in laying and testing the water supply mains.
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Design a separate sewer running full which receives only storm water from a water shed of area 50 hectares. The duration of storm is 15 minutes. The impermeability factor of the total area is 0.50. The coefficient of rugosity “n”= 0.013 and i = 0.01.
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Define B.O.D. How is it estimated?
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Explain the circular sewer with the help of a sketch and list any two merits and demerits.
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List the methods of disposal of sewage in detail. Describe any one of the methods.
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Explain the principle and operation of primary sedimentation tanks.
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Why is sludge digested anaerobically in a conventional sewage treatment plant?
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In designing a rectangular grit chamber for the following data: Flow = 40 mld., grit of specific gravity = 2.65 and size = 0.2 mm to be removed. Find the a) Settling velocity of 0.2 mm particles, b) Critical horizontal velocity of flow, and c) Size of the grit chamber.
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