Environmental Engineering | MCQs

Explanation

Washing soda is also known as sodium carbonate (Na2CO3).

It is used to remove permanent hardness of water.

Permanent hardness is caused by the presence of magnesium and calcium sulfates or chlorides in water, which cannot be removed by boiling.

Washing soda helps to precipitate these minerals, making the water softer.

Explanation

Tertiary treatment involves filtering, chlorination, and removing salts to further purify wastewater.

It is the final and most advanced stage of wastewater treatment.

Explanation

Reverse osmosis is a water purification process

that uses a partially permeable membrane to remove ions,

unwanted molecules and larger particles from drinking water.

Explanation

Sanitation also includes the management of human waste and solid waste as well as drainage management.

Explanation

Coagulation often precedes rapid sand filtration to aggregate fine particles into larger clumps for easier removal during the filtration process.

However, if coagulation is not required due to the absence of significant turbidity

it may be skipped, making it the step that doesn't belong in the sequence.

Steps in the purification of water using a rapid sand filter

1. Coagulation

2. Rapid mixing

3. Flocculation

4. Sedimentation and THEN

5. Filtration: using the rapid sand filter

Explanation

Wet oxidation is a form of hydrothermal treatment. It is the oxidation of dissolved or suspended components in water using oxygen as the oxidizer.

AGM 25-12-2022