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GATE CE 2020 Environmental Engg. Quiz 4 (App update required to attempt this test)
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Question 1
Calculate the efficiency(%) of a high rate trickling filter which has volume of 1200 m3 and sewage flow is 30 ML/day. BOD of the sewage coming from the PST is 200 mg/l. Take recirculation ratio 0.5.
Question 2
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.
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 3
Match the following values of permissible BOD for disposal of sewage:
List - I
A) Lake water
B) River water
C) Land
D) Sea
List - II
1) 100 mg/l
2) 50 mg/l
3) 500 mg/l
4) 30 mg/l
5) 20 mg/l
List - I
A) Lake water
B) River water
C) Land
D) Sea
List - II
1) 100 mg/l
2) 50 mg/l
3) 500 mg/l
4) 30 mg/l
5) 20 mg/l
Question 4
250 cumecs of sewage of Varanasi city containing no dissolved oxygen (DO) is discharged into the Ganga river which is fully saturated with oxygen and flowing at a rate of 2000 cumecs with a minimum velocity of 0.15 m/sec. The 5 day BOD of sewage is 350 mg/litre. The value of critical Do (in mg/l) deficit is
[Assume coefficient of purification of river is 3.0, coefficient of deoxygenation is 0.12, the ultimate BOD is 150% of the 5 day BOD and sarurated DO of river is 12 mg/litre]
[Assume coefficient of purification of river is 3.0, coefficient of deoxygenation is 0.12, the ultimate BOD is 150% of the 5 day BOD and sarurated DO of river is 12 mg/litre]
Question 5
A township is to treat 8,00,000 litres sewage per day which has a 5 day BOD of 175 ppm. An oxidation pond is used for this purpose. The effluent can have a BOD of 25 ppm. If the required area of pond is 25000 m2, then the organic loading rate will be _______ kg BOD/ha/day.
Question 6
A landfill is to be designed to serve a population of 200000 for a period of 25 years. The solid waste (SW) generation is 2 kg/person/day. The density of the un-compacted SW is 100 kg/m3 and a compaction ratio of 4 is suggested. The ratio of compacted fill (i.e. SW + cover) to compacted SW is 1.5. The landfill volume (in million m3) required is _______.
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