Apr 14, 20202 min
Updated: Apr 26, 2020
281. The effective size (ES) of sand and its uniformity coefficient (UC) are the
usually specified parameters for sand filters. In slow sand filters, as compared to
rapid sand filters ES is less but UC is more
282. If only ammonia was present in water, the only change in Fig.6.4 would have been that the curve would
be passing through the origin
283. Which one of the following is the purpose of providing a surge tank in a pipeline carrying water ?
to protect the pipeline against water hammer
284 Rapid mixing unit - 30 second
Flocculator- 30 minute
Propeller mixing unit 10 second
Sedimentation tank-1.5 hours
285. The maximum flow occurs in an eggshaped sewer when the ratio of depth
of flow to vertical diameter is 0.95
286. The following three stages are known to occur in the biological action involved in the process of sludge digestion :
1. Acid fermentation.
2. Acid regression
3. Alkaline fermentation.
287. Fresh sludge has moisture content of 99% and, after thickening, its mojsture content is reduced to 96%. The reduction in volume of sludge is 75%
288.
Dissolved solids-Reverse osmosis
Colloidal solids-Coagulation
Volatile solds-Digestion
Settleable solids-Sedimentation
289. In the oxidation ditch, the excess sludge is taken to drying beds
290. The flow sheet of the liquid stream of a sewage treatment scheme consists of
1. screen chamber
2. grit chamber
3. primary settling tank
4. trickling filter
5. secondary settling tank
291. Oxidation ditch ... algae
292. The two main gases liberated from an anaerobic sludge digestion tank would
include carbon dioxide and methane
293. Which one of the following sewage treatment units has a parshall flume
grit chamber
294. Which one of the following is least important in the activated sludge process? the sludge volume index of the return sludge to be less than 200
295. The following zones are formed in a
polluted river:
The correct sequence in which these zones occur progressively downstream in a
polluted river is
1. zone of pollution
2. zone of active decomposition
3. zone of recovery
4. zone of clear water
296.
Acid water-Mining
SO₂- Volcanoes
CO - Automobiles
Fly ash-Thermal power station
297. Aerosol is dispersion of small solid or liquid particles in gaseous media
298. Water present in an artesian aquifer is usually above atmospheric pressure
299. Consider the following statements :
The daily per capita consumption of water apparently increases with
1. higher standard of living of people
2. availability of sewerage in the city
3. wholesome and potable quality of water
300.
Incrustation of filter sand media- Washing the filter with sodium hydroxide or bleaching powder of occasionally
Air binding & development of negative head-Increasing the depth of water during filter operation by about 15-20 cm as compared to the normal depth maintained during daily operation and more frequent backwashing
Mud ball formation - Through back washing with salt solution after soaking the filter in it
Slime growth on filter-Compressed air scouring for about 4 minutes at the time of backwashing and manual surface raking