Question:

During the primary treatment of sewage, solid particles that settle down are called

Updated On: Jul 6, 2022
  • floes
  • primary sludge
  • activated sludge
  • anaerobic sludge
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The Correct Option is B

Solution and Explanation

Primary or physical treatment is the process of removal of small and large, floating and suspended solids from sewage through two processes of filtration and sedimentation. First floating and suspended matter is removed through sequential filtration with progressively smaller pore filters, The sediment is called primary sludge while the supernatant is called effluent. The primary sludge traps a lot of microbes and debris. It is subjected to composting, land fill or anaerobic digestion to produce biogas and manure.
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Concepts Used:

Microbes in Human Welfare

There are several valuable microorganisms that are beneficial to humans in various manners such as:

In Household Products

  1. Fermentation of milk to produce yogurt.
  2. Milk cuddling to compose curd, cheese, and paneer.

In Industrial Products

  1. Production of beverages such as wine, beer, whiskey, brandy, or rum.
  2. Production of antibiotics such as Penicillin and other chemical substances to kill or retard the expansion of disease-causing microbes.

Fermented Beverages

  1. A fermentor is used to produce microbes on a large scale for industrial purposes.
  2. The brewer’s yeast (Saccharomyces cerevisiae) is used to make ethanol. At this time, the yeast ferments malted cereals and fruit juices.

Antibiotics

  1. The term antibiotic means “against life”. These materials can kill or destroy the growth of other microbes.