Tag: hygiene - a key to healthy life

Questions Related to hygiene - a key to healthy life

Which process involved in waste water convertion into drinkable water?

  1. Precipitation

  2. Condensation

  3. Filtration

  4. Nutrient cycle


Correct Option: C

Which of the following are correctly matched ? 
1. Arsenic poisoning - Black-foot disease
2. Secondary effluent treatment - Biological process 
3. Pyrolysis - Waste disposal
4. Tubifex - Water pollution indicator 
5. Biomagnification - Degradable pollutants 

  1. 1, 2, 3 and 5

  2. 1, 3, 4 and 5

  3. 2, 3, 4 and 5

  4. 1, 2, 4 and 5

  5. 1, 2, 3 and 4


Correct Option: E
Explanation:

Biomagnification refers to increase in concentration of the toxicant at successive trophic levels. This happens because a toxic substance accumulated by an organism cannot be metabolised or excreted, and is thus passed on to the next higher trophic level. This phenomenon is well known for mercury and DDT. 

During sewage treatment the microorganisms participate under which step?

  1. Primary

  2. Secondary

  3. Teritiary

  4. None of the above


Correct Option: B
Explanation:

Sewage treatment generally involves three stages, called primary, secondary and tertiary treatment. 

Primary treatment consists of temporarily holding the sewage in a quiescent basin where heavy solids can settle to the bottom while oil, grease and lighter solids float to the surface. 
Secondary treatment removes dissolved and suspended biological matter. Secondary treatment is typically performed by indigenous, water-borne micro-organisms in a managed habitat. Secondary treatment may require a separation process to remove the micro-organisms from the treated water prior to discharge or tertiary treatment. 
Tertiary treatment allows rejection into a highly sensitive or fragile ecosystem like estuaries, low-flow rivers, coral reefs etc. 

The domestic sewage in large cities

  1. Has a high BOD level, as site containes both aerobic and anaerobic bacteria.

  2. Is processed by aerobic and then anaerobic bacteria in the secondary treatment in the Sewage Treatment Plants (STPs).

  3. When treated in STPs does not really require the aeration step as the sewage contains adequate oxygen.

  4. Has very high amounts of suspended solids and dissolved salts.


Correct Option: B
Explanation:
Secondary (biological) treatment is the method to remove the dissolved organic matter that escapes primary treatment. This is achieved by microbes consuming the organic matter as food, and converting it to carbon dioxide, water, and energy for their own growth and reproduction. The biological process is then followed by additional settling tanks to remove more of the suspended solids. In this method, waste water first treated with microbes aerobically and anaerobically in anaerobic digester tank.