Question

Given below is a jumbled sequence of the processes involved in a wastewater treatment plant. Select the correct option that gives the correct sequence of the processes.

(A) Sludge is scraped out and skimmer removes floating grease.
(B) Water is made to settle in a large tank that is sloped in the middle.
(C) Large objects like plastic bags are removed by passing wastewater through bar screens.
(D) Sand, grit and pebbles are made to settle by decreasing the speed of incoming wastewater.
(E) Wastewater enters a grit and sand removal tank.

• A. A → B → C → D → E
• B. C → D → E → B → A
• C. C → E → D → B → A
• D. A → D → C → E → B

Answer 1

The correct option is C C → E → D → B → A

Wastewater is treated in a wastewater treatment plant that follows several steps in a defined manner. The steps arranged as per their correct sequence from the options given are-

• Wastewater is first passed through bar screens to remove large objects such as rags, cans, plastics, etc.
• It then enters the sand and grit removal tank. In this step, sands, grits aand pebbles settle down by decreasing the speed of incoming water.
• Water is then allowed to settle in a large tank which is sloped towards the middle.
• Solids like faeces settle at the tank bottom and are called sludge which are removed with a scraper.
• Floatable solids like oil and grease are removed with a skimmer.