Environmental Engineering Test 1

Question 1
2 / -0.33

In water softening processes, the purpose of re-carbonation after using lime-soda process is for

A
Excess soda removal from water

B
Carbonate hardness removal

C
Non-carbonate hardness removal

D
Conversion of precipitate to soluble form

Question 2
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An aeration basin with a volume of 400 m³ contains mixed liquor with a suspended solids concentration of 1000 mg/l. The amount of mixed liquor suspended solids in the tank is

A
500 kg

B
250 kg

C
600 kg

D
400 kg

Question 3
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When the friction factor is increased from 0.01 to 0.02, the self-cleansing velocity of the pipe _____

A
becomes 4 times

B
becomes 0.25 times

C
becomes 1/√2 times

D
becomes √2 times

Question 4
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The incorrect statement related to carbon/Nitrogen ratio is

A
Lower initial C/N ratio slows down the rate of decomposition.

B
Higher initial C/N ratio leads to cell destruction to obtain nutrition.

C
Higher initial C/N ratio leads to lower conservation of nitrogen.

D
Optimal C/N ratio in anaerobic digestion is 30 to 50%.

Question 5
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If the total hardness present in a water sample is 320 mg/L as CaCO₃ and total alkalinity is 280 mg/L as CaCO₃, the CH and NCH of the sample is (in mg/L as CaCO₃)

A
280 and 40

B
40 and 280 C

C
320 and 0

D
0 and 320

Question 6
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A standard multiple-tube fermentation test was conducted on a sample of water. The analysis of the confirmed test are:
Sample size (mL)
No. of positive result out of five
No. of negative results out of five
10
4
1
1
3
2
0.1
2
3
0.01
0
5
MPN index for combinations of positive results when 5 tubes are used per dilutions (10 mL, 1 mL, 0.1 mL)
Combination
MPN index per 100 mL
5 – 3 – 2
33
4 – 3 – 2
26
0 – 2 – 3
22
3 – 2 – 0
7
Using the MPN index table, the most probable number of the sample is

A
260

B
26

C
7

D
70

Question 7
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The aerobic method of mechanical composting practised in India is called:

A
Indore method

B
Nagpur method

C
Bangalore method

D
Bhopal method

Question 8
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NO_X presence in the atmosphere is detected by which of the following method?

A
NDIR Analyzer

B
West and Greek Method

C
Jacob & Oyster Method

D
High Volume Sampler Method

Question 9
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Which of the following statement is not true regarding the usage of copperas as coagulant?

A
Copperas is ineffective in the removal of color from the water sample.

B
It functions effectively for pH range above 8.5.

C
It is costlier than alum.

D
Combination of ferric sulphate and ferric chloride gives chlorinated copperas.

Question 10
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A raw water sample collected from a lake was subjected to tests for estimation of solids. A one liter of raw water when passed through filter paper, the moist weight of filter paper is 225 gm which after oven drying was reduced to 200 grams. The filtered water is then over dried for 5 hours resulting in 150 grams of solids, the remaining solid when subjected to the heating in the metal furnace was reduced to 100 grams. A separate test on the raw material conducted through gravimetry resulted in 300 milligrams of solids. The non-volatile and volatile dissolved solid (in mg/liter), in the water sample respectively are ____.

A
300 and 200

B
200 and 150

C
150 and 100

D
100 and 50

Question 11
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The present population of a sector in Noida is 200,000 with an average water consumption of 50000 m³/d. The design capacity of water treatment plant is 75000 m³/day. Due to expansion of the sector it is expected that the population will increase to 325,000 during the next 10 years. The number of years from now when the plant will reach its design capacity assuming an arithmetic rate of population growth, will be

A
7.5 years

B
8 years

C
8.5 years

D
9 years

Question 12
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A branch sewer to be designed at the half flow condition for a town for the population of 10000 has an average daily water supply at the rate of 200 lpcd. 80 percent of the water supplied goes to drain. The sewer is designed to carry three times of average discharge. If the branch sewer is laid at the slope of 0.005 and the manning’s roughness coefficient for the sewer material is 0.009, then the suitable diameter of the pipe is _________

A
0.15 m

B
0.25 m

C
0.32 m

D
0.41 m

Question 13
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The amount of bleaching powder having 25% chlorine required to chlorinate water supply for 50000 people at the rate of 50 lpcd having a chlorine demand of 2 mg/ℓ is

A
5 kg

B
20 kg

C
50 kg

D
200 kg

Question 14
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A town with a population of 60000 produces a solid waste at 3 kg/capita/day. A survey on this waste reveals that the 50 percent of the waste constitutes of food waste having a specific weight of 300 kg/m³, while 30 percent is dirt and ash with a specific density of 500 kg/m³ and the remaining 20 percent of waste has weighted average specific density of 100 kg/m³. If this solid waste is to be dumped directly on the landfill of 5 meters depth. Calculate the area of the landfill (in hectares) required annually to accommodate such waste disposal.

A
5-6

B
54-61

C
57-66

D
59-62

Question 15
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An anaerobic digester is designed to remove 85% of BOD of industrial organic waste with an ultimate BOD of 2000 mg/L. If the sludge age (θ_c) is 10 days, estimate the amount of sludge (kg/day) to be wasted on a daily basis_____.
Assume the following data
Flow (Q) of 0.1 MLD,
Y = 0.1 kg/kg,
k_d = 0.01 per day and
k = 0.23 per day

A
10-11

B
104-111

C
107-116

D
109-112

Question 16
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A town having a population of 30000 persons is producing sewage at the rate of 120 lpcd with initial BOD of waste being 250 mg/l. If 30% of the B.O.D is removed in the primary clarifier itself, then determine the minimum required volume (in m³) of high rating trickling filter for achieving desired effluent BOD of 30 mg/l. (Assume recirculation ratio of 1.5).

A
1495-1520

B
14954-15201

C
14957-15206

D
14959-15202

Question 17
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Three sources generate noise levels of 60 dB, 80 dB and 100 dB respectively. The average sound pressure level is (in dB upto 2 decimal places) _______

A
91-92

B
914-921

C
917-926

D
919-922

Question 18
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A city having a population of 100000 with an average demand of 160 lpcd to be provided with a rapid sand filter. Each backwashing period is of 30 mins and 5% of filtered water is used for backwashing. If the rate of filtration is 4000 L/hr/m² and area of 1 filter bed is 50 m² the number of filters required allowing 1 as a stand by is

A
8-8

B
84-81

C
87-86

D
89-82

Question 19
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An ideal horizontal flow setting tank having a plan area of 800 m² is used for settling of solids in water flowing at a rate of 32000 m³/day. Assuming stokes law to be valid, the percentage removal of spherical sand particles of 0.018 mm diameter with a specific gravity 2.7 is (Take ν_water = 1.01 × 10^-2 cm²/s)

A
63.5-65.5

B
63.54-65.51

C
63.57-65.56

D
63.59-65.52

Question 20
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An electrostatic precipitator with collecting area “A” m² has existing efficiency of 92 % is installed at a particular place. If it is desired to increase its existing efficiency to 98%, the collector area must be increased ‘x’ times that of the existing collecting area. The suitable value of x, rounded up to two decimal places is _______

A
1.5-1.7

B
1.54-1.71

C
1.57-1.76

D
1.59-1.72

Submit Test

Sample size (mL)	No. of positive result out of five	No. of negative results out of five
10	4	1
1	3	2
0.1	2	3
0.01	0	5

Combination	MPN index per 100 mL
5 – 3 – 2	33
4 – 3 – 2	26
0 – 2 – 3	22
3 – 2 – 0	7

Environmental E...

Question 1

Excess soda removal from water

Carbonate hardness removal

Non-carbonate hardness removal

Conversion of precipitate to soluble form

Question 2

500 kg

250 kg

600 kg

400 kg

Question 3

becomes 4 times

becomes 0.25 times

becomes 1/√2 times

becomes √2 times

Question 4

Lower initial C/N ratio slows down the rate of decomposition.

Higher initial C/N ratio leads to cell destruction to obtain nutrition.

Higher initial C/N ratio leads to lower conservation of nitrogen.

Optimal C/N ratio in anaerobic digestion is 30 to 50%.

Question 5

280 and 40

40 and 280 C

320 and 0

0 and 320

Question 6

260

26

7

70

Question 7

Indore method

Nagpur method

Bangalore method

Bhopal method

Question 8

NDIR Analyzer

West and Greek Method

Jacob & Oyster Method

High Volume Sampler Method

Question 9

Copperas is ineffective in the removal of color from the water sample.

It functions effectively for pH range above 8.5.

It is costlier than alum.

Combination of ferric sulphate and ferric chloride gives chlorinated copperas.

Question 10

300 and 200

200 and 150

150 and 100

100 and 50

Question 11

7.5 years

8 years

8.5 years

9 years

Question 12

0.15 m

0.25 m

0.32 m

0.41 m

Question 13

5 kg

20 kg

50 kg

200 kg

Question 14

5-6

54-61

57-66

59-62

Question 15

10-11

104-111

107-116

109-112

Question 16

1495-1520

14954-15201

14957-15206