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Environmental (201-220)

Updated: Apr 26, 2020

201.Consider the following statements regarding confined aquifers

1. The aquifer is bound at top and below by impervious strata.

2. The pressure of water is greater than atmospheric pressure.

3. The aquifer is fully saturated. Of the above statement


202.Consider the following statements in respect of slow sand filters

1.Qualitywise they are more efficient than Rapid Sand filters. 2.Their flow rate is much smaller than that of pressure filter


203. Type II settling in water treatment is defined as settling of flocculant particles in dilute suspensions.



1. Lime soda process ..... Softening.

2. Nalgonda technique...... Fluoride removal.

3. Ozonation.... Disinfection.


205. The chlorine demand of a water sample was found to be 0.2 mg/1. The amount of bleaching powder containing 30% available chlorine to be added to treat one litre of such a water sample is: 0.67 mg


206.Consider the following statements: In water supply distribution network, the

dead-end system is not favoured because

1. the pressure at the dead-ends becomes undesirably low in the case of

additional extensions.

2. it is difficult to maintain residual chlorine levels at the dead-ends.

3. at the time of repairs, service connections beyond the point of repair are deprived of water


207. The ideal residual pressure at the farthest consumer's tap in a properly designed water distribution system is in the range of 0.031 to 0.035 N/mm²


208. Under natural conditions of flow, an unpolluted river would contain less dissolved oxygen in summer than in winter.


209. Consider the data presented in the following table:

In the data presented above, the value of K has followed the correct trend


210. For the combined sewerage system, egg shaped sewers are preferred because they offer good flow velocity during the dry-weather-flow condition



Sludge volume index-Activated sludge process Thickening of sludge-Settling in Secondary sedimentation tank Scum removal-Settling in primary sedimentation tank Recycling effluent- Filteration in trickling filter


212. Various unit operations exist in a sewage treatment plant. These would include

1. screening

2. grit removal

3. primary sedimentation

4. aeration

5. secondary sedimentation


213. An aeration basin with a volume of 400 m³ contains mixed liquor with suspended solid concentration of 1000 mg/I. The amount of mixed liquor suspended solids in the tank is 400 kg


214. The following reactions take place during anaerobic digestion of organics:

1. acid fermentation

2. acid regression.

3. alkaline fermentation

4. methane production


215. Traps are used in household drainage systems to prevent entry of foul gases in the house


216. Coal based thermal power stations pollute the atmosphere by adding



217. Area method of land filling is most suitable when adequate depth of cover material is available at the site.



A. Surface water (river or canal)-Coagulation,flocculation,sedimentation,filtration and disinfection B. Water from infiltration gallery-Aeration,coagulation,sedimentation and disinfection C.Lake/pond water-CuS0 treatment,coagulation,sedimentation,filtration and disinfection D.Tube well water-Disinfection


219. The frow chart of a water treatment plant is shown in Fig:

If it is proposed to defluoridate the water using 'Nalgonda treatment', then it should be done by adjusting the dose of lime and alum


220. Two reservoirs at different levels are connected by two parallel pipes of

diameter 2d and d. The ratio of the flows in the two pipes (large : smaller) is


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