A thermodynamic system is taken from state A to B along ACB and is brought back to A along BDA as shown below in the P-V diagram. The net work done during the complete cycle is given by the area covered by_________________?
(A) P1ACBP2P1
(B) ACBB1A1A
(C) ACBDA
(D) ADBB1A1A
The main pollutant in waste water discharged from a petroleum refinery is oil (both in free and emulsified form). Free oil is removed by_________________?
(A) Biological oxygen pond
(B) Aerated lagoons
(C) Trickling filters
(D) Gravity separator having oil skimming devices
Noise emitted by a ventilation fan at a distance of 3 metres is about _____________ decibels?
(A) 85
(B) 105
(C) 125
(D) 145
Presence of ____________ in water stream are deleterious to aquatic life?
(A) Soluble and toxic organics
(B) Suspended solids
(C) Heavy metals and cyanides
(D) All
BOD of raw municipal sewage may be in the range of about _____________ mg/litre?
(A) 1-2
(B) 5-10
(C) 150-300
(D) 2000-3000
Iron & manganese present in the polluted water is removed by __________________?
(A) Simple filtration
(B) Oxidation followed by settling & filtration
(C) Chemical coagulation
(D) Chlorination only
TLV of aldrin in public water supply system is about ____________ μg/litre?
(A) 0.5
(B) 17
(C) 357
(D) 1097
Aerobic biological oxidation ponds used for the purification of polluted water__________________?
(A) Destroys/removes pathogen from the sewage
(B) Is not very effective for non-biodegradable substances (e.g. ABS) containing effluents
(C) Destroys/removes pathogen much more effectively if the sewage is chlorinated
(D) All
Presence of excess fluorine in water causes__________________?
(A) Dental cavity
(B) Tooth decay
(C) Fluorosis
(D) Respiratory disease