top of page

Environmental (141-160)

Updated: Apr 26, 2020

141. For normal sludge, the value of sludge index for Indian conditions is 150 to 350


142. When there is no recirculation of sewage, then recirculation factor is 1


143. For the same solid content, if the quantity of sludge with moisture content of 98% is X, then the quantity of sludge with moisture content of 96% will be X/2


144. A pipe which is installed in the house drainage to preserve the water seal of traps is called antisiphonage pipe


145. In the two-pipe system of house plumbing, the pipes required are one soil pipe, one waste pipe and two vent pipes


146. The pipe which is used to carry the discharge from sanitary fittings like bath

rooms, kitchens etc. is called waste pipe


147. The gas from sludge digestion tank is mainly composed of methane


148. Most of the bacteria in sewage are saprophytic


149. The process of lagooning is primarily a means of disposing of sludge


150. The biochemical treatment of sewage effluents is essentially a process of oxidation


151. To divert excessive flow from combined sewers, the most commonly used weir is a leaping weir


152. Chlorine is used in the treatment of sewage to help grease separation


153.In the design of grit chambers the maximum velocity of flow is 30

cm per second



Acidity-Carbon dioxide Alum-Flocculation Cyclone-Particulate matter Skimming tank-Oils and greases


155.If the diameter of the main pipe is taken less than economic diameter then

1. head loss will be high

2. cost of pipe will be less


156.Incrustation of the tubewell pipes may result in reduced discharge from tubewell


157. The maximum velocity occurs in an egg shaped sewer when the ratio of depth of flow to vertical diameter is 0.81


158. Shrouding is provided in slotted pipe tubewell


159. If in a test conducted for determining relative stability, the period of incubation at 20°C is t days, the relative stability in % is given by 100[1 -(0.794)]


160. Ozone layer in the upper atmosphere is getting destroyed owing to its reaction with chlorofluorocarbons

10 views0 comments


bottom of page