1. Fill in the blanks:
(a) Cleaning of water is a process of removing ____________.
(b) Wastewater released by houses is called ____________.
(c) Dried ____________ is used as manure.
(d) Drains get blocked by ____________ and ____________.
(a) Cleaning of water is a process of removing contaminants.
(b) Wastewater released by houses is called sewage.
(c) Dried cow dung is used as manure.
(d) Drains get blocked by plastic and fats.