a. Cleaning of water is process of removing contaminants.

Contaminants are the suspended and dissolved impurities of water.

b. Wastewater released by houses is called sewage.

Sewage is a liquid waste which causes water and soil pollution.

c. Dried sludge is used as manure.

Semi-solid wastes like faces that settle down at the bottom during wastewater treatment are called sludge.

d. Drains get blocked by cooking oil and fats

Cooking oil and fats should not be thrown down the drain. They can harden and block the pipes.