Large scale water purification
What percent of the water is purified by storage only?
90%
Chemical composition of bleaching powder
CaOCl2
Full form of NTU
Nephelometric turbidity units
The recommended maximum limit of fluoride in water is?
1.5 mg/l
What is the minimum recommended concentration of free chlorine?
0.5 mg/l
Name the 4 elements of a slow sand filter.
supernatant water
bed of graded sand
under drainage system
filter control valves
Perchloron contains _______% available chlorine.
60 to 70
Name the physical parameters in water quality criteria
Turbidity
Colour
Taste and odour
Temperature
Name the toxic inorganic constituent present in pipes.
Lead
What is break point chlorination?
The point where chlorine demand is met
What cleaning method is used in rapid sand filter when the filter bed becomes clogged?
Backwashing
Candle in the berkefeld filter is made up of _________
kieselgurh or infusorial earth
The primary bacterial indicator recommended for water quality is?
Coliform group of organisms
Cadmium accumulates primarily in which organ?
Kidneys
Heavily polluted waters are purified by _________.
Superchlorination.
What is the named biologically active layer on the surface of a slow sand filter called?
Schmutzdecke
How many grams of bleaching powder is used to disinfect 1000 litres of water?
2 to 2.5 grams
Name any one water-based disease
Dracunculiasis and schistosomiasis
The enzyme glutathione peroxidase has which inorganic constituent?
Selenium
Name the test that determines free and combined chlorine separately.
Orthotolidine arsenite test
Disinfecting action of chlorine is mainly due to ____________
Hypochlorous acid
Double pot method was devised by which institute?
National Environmental Engineering Research Institute,Nagpur
The presence of which bacteria in the water indicates recent fecal pollution of water?
Faecal streptococci
Formula for tolerable daily intake
NOAEL or LOAEL/ UF
What term describes the amount of chlorine consumed by water before residual chlorine appears?
Chlorine demand