In septic tanks, decomposition of organic bacteria, is done by

The bottom of the sewage inlet chamber of septic tanks, is provided an outward slope

A

1 in 5

B

1 in 10

C

1 in 15

D

1 in 20

The sewage treatment in septic tanks is due to

A

Anaerobic decomposition

B

Aerobic decomposition

C

Parasitic decomposition

D

None of these

Which one of the following statements regarding septic tanks is wrong?

A

A gap of 7.5 cm between the bottom of the covering slab and the top level of scum is provided

B

The outlet invert level is kept 5 to 7.5 cm below the inlet invert level

C

The minimum width of septic level is 90 cm

D

The depth of tank is kept equal to its width

Septic tanks are used for the __________ of the deposited solids.

A

Separation

B

Anaerobic decomposition

C

Aerobic decomposition

D

None of these

In septic tanks,

A

Free board of 0.3 m may be provided

B

The baffles or tees are extended up to top level of scum

C

The clear space between the baffle top and covering slab is about 7.5 cm

D

All the above

The rate of accumulation of sludge in septic tanks is recommended as

A

30 litres/person/year

B

25 litres/person/year

C

30 litres/person/month

D

25 litres/person/month

The digested sludge from septic tanks, is removed after a maximum period of

A

3 years

B

3.5 years

C

4 years

D

5 years

Main component of sewage gas produced during aneorobic decomposition of organic waste (by suitable bacteria) during sewage disposal is

A

H₂

B

CH₄

C

CO₂

D

N₂

A rectangular tank 10 inch by 8 inch by 4 inch is filled with water. If all of the water is to be transferred to cube-shaped tanks, each one 3 inches on a side, how many of these smaller tanks are needed?

A

9

B

12

C

16

D

21

Two tanks are filled to capacity with automobile fuel. The first tank holds 600 gallons more than the second tank. If 100 gallons were to be pumped from each tank, the first tank would then contain 3 times as much fuel as the second tank. What is the total number of gallons of fuel in the two full tanks?

A

1,400

B

1,200

C

1,000

D

900

In septic tanks, decomposition of organic bacteria, is done by

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