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# Environmental Engineering: Nuclear Quiz 2

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Question 1

What is the addition of (–64)10 and (80)16?

Question 2

What is the intensity of active earth pressure at a depth of 10.0 m in dry sand with an angle of shearing resistance of 30o and unit weight of 18 kN/m3?

Question 3

Which of the following statements are true?
1) Mesophilic bacteria act on the sewage at a temperature of 20-40 °C
2) Thermophilic bacteria act on the sewage at a temperature of 60-80 °C
3) Digestion is generally done in thermophilic range.
4) Sudden admission of industrial waste reduces the pH.

Question 4

Consider the following statements:

a. Presence of nitrogen in a waste sample is due to the decomposition of proteins and carbohydrates.

b. When BOD/COD =0, waste water is toxic.

Which of the above statements are correct?

Question 5

What is theoretical oxygen demand of 150 mg/L glucose solution?

Question 6

Following happens to be the operating data for conventional activated sludge treatment plant :
(i) Waste water flow=40000 m3/d
(ii) Influent BOD= 300mg/l
(iii) Effluent BOD=30 mg/l
(iv) Mixed liquor suspended solids(MLSS)=2000 mg/l
(v) Volume of aeration tank=10000 m3
The Food/Microorganism (F/M) ratio (in kg BOD per day/kg of MLSS) is

Question 7

An activated sludge aeration tank (length = 20.0 m; width = 15.0 m; effective liquid depth = 5 m) has the following parameter:
Flow = 0.08 m3/sec
Soluble BOD5 after primary settling = 120 mg/l
Mixed liquor suspended solids (MLSS) = 2000 mg/l
Mixed liquor volatile suspended solids (MLVSS) = 1600 mg/l
30 minute settled sludge volume = 250 ml/l
Return sludge concentration = 1000 mg/l
The hydraulic retention time (in hrs) and sludge volume index (in ml/gm) will be

Question 8

The census record of a particular town is shown in table. The population (in thousands) for the year 2020 by decreasing growth rate method will be

Question 9

The slope of a 1.0 m diameter concrete sewer laid at a slope of 1 in 1000, develops a velocity of 1 m/s, when flowing full. When it is flowing half-full, the velocity of flow through the sewer will be

Question 10

A sludge of 140 m3 has moisture content of 95 percent. The volume, if moisture content changes to 90 percent, will be ______ m3.
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