Saturday, January 4, 2014

Environmental Engg. Notes for GATE, PSUs preparations - part 9

Hello there,

Welcome to the part 9 of the one liner notes useful for the preparation of GATE and other similar examinations.
  • To divert excessive flow from combined sewers, the most commonly used weir is a leaping weir.
  • Chlorine is used in the sewage treatment to help grease separation.
  • The maximum flow of flow is about 30 cm per second.
  • If the diameter of the main pipe is taken less than economic diameter then head loss will be high, cost of pipe will be less but cost of pumping will be high.
  • Incrustation of the tube-well pipes may result in reduced discharge from tube-well.
  • The maximum velocity occurs in an egg shaped sewer when the ratio of depth of flow to vertical diameter is 0.81.
  • Shrouding is provided in slotted pipe tube-well.
  • Ozone layer in the upper atmosphere is getting destroyed owing to its reaction with chlorofluorocarbons.
  • The intensification of green house effect is attributed to the increased level of carbon di-oxide.
  • Electrostatic precipitators are used as pollution control device for the separation of particulate matter.
  • Peroxy-acyl-nitrate(PAN) and ozone are secondary pollutants.
  • Sulphur di-oxide and nitrogen oxides are primary air pollutants.
  • The spray towers can be used to control gaseous pollutants and particulate pollutants.
  • The depletion of the ozone in the outer atmosphere may result in increased skin cancer cases.
  • The rain is generally termed acidic if the pH of the water falls below 5.
  • The acidic rains are caused by SO2 and NOx.

Thanks for your visit!

Reference: Book " Civil Engineering Objectives" by S P Gupta and S P Gupta.