Which one of the following statements regarding septic tanks is wrong :
In septic tanks, decomposition of organic bacteria, is done by
The average temperature of sewage in India, is
3.0 ml of raw sewage is diluted toml. The D.O. concentration of the diluted sample at the beginning of the test was 8 mg/l. After 5 day-incubation at 20°C, the DO. concentration was 5 mg/l. The BOD of raw sewerage is
Pick up the incorrect statement from the following :
In a residential colony, sewers of diametersmm,mm andmm were laid with a gradient 1 inWhich portion of the sewage system does not choke in due course of time
Pick up the correct statement from the following :
If the grit in grit chambers is 4.5 million litres per day, its cleaning is done
The pH value of sewage is determined with the help of
A well oxidized sewage contains nitrogen mainly as
Drop manholes at the junctions of sewer lines, are provided if
The self-cleansing velocity of water flowing through pipe lines, is
In circular sewers if depth of flow is 0.2 times the full depth, the nominal gradient,
The stone ware sewers
The most widely used pump for lifting sewage is
The arrangement made for passing the sewer line below an obstruction below the hydraulic gradient lines called
The pH value of sewage is determined with the help of
Pick up the correct statement from the following :
If D is the diameter of upper circular portion, the overall depth of New Egg shaped sewer section, is
For trunk sewers more than 1.m in diameter, the ratio of the maximum daily sewage flow to the average daily sewage flow is assumed
The gas evolved in sewers is
A safety lamp when inserted in the upper portion of a manhole causes flames. It indicates the presence of
The most effective arrangement for diverting excess storm water into a natural drainage, is
'Cowl' is provided at
The sewer which resists sulphide corrosion, is
The angle subtended by the surface of sewer water with partial flow, at sewer centre is 120°, the depth of sewerage is
You are asked to design sewer pipes of diameters 0.4 m to 0.9 m at maximum flow, you will assume the sewer flow running at
Discrete or granular particles change their
In sewers the velocity of flow should not be
During putrifaction process of sewage the gas given off, is
At the junction of sewers
The maximum depth of sedimentation tanks, is kept
Assertion (A) : A free board of 0.3 m is provided above the top sewage line in septic tanks.
Reason (R) : It helps to accommodate the scum in the septic tank.
Large diameter sewers subjected to external pressure alone, are reinforced
The sewer which transports the sewage to the point of treatment, is called
The sewer which resists sulphide corrosion, is
Imhoff cone is used to determine
Ventilating shafts are provided to a sewer line at every
For a peak discharge of 0.cumec, with a velocity of 0.9 m/sec, the diameter of the sewer main, is
If D is the diameter of a circular sewer and D' is the top horizontal diameter of an equivalent egg shaped section, the relationship which holds good, is
Sewer pipes are designed for maximum discharge withtovacant cross-sectional area for
A circular sewer section is preferred to because
Primary treatment of sewage consists of removal of
The reduced levels of the string at the consecutive sight rails A and B are 203.m, 203.m respectively. If the difference of their R.D.s ism, the gradient of the sewer line is
Pick up the correct statement from the following :
Kjedahl nitrogen is a mixture of
The sewage discharge in a detritus tank of a treatment plant islitres/sec with flow velocity of 0.2 m/sec. If the ratio of width to depth isthe depth is
Which one of the following part of human body withstands minimum radiation
The pH value of fresh sewage is usually
A nuisance is experienced in diluting water if dilution factor is less than