Question

Why municipal sewage first separated into degradable and non degradable wastes

Answer 1

Substances which can be Brocken up by biological processes is biodegradable
Substances which cannot be broken up by natural processes is non biodegradable

Sewage is separated as biodegradable and non biodegradable
Because non biodegradable substances need to be treated etc they are harmful to the environment. They persist for long time

Answer 2

Municipal sewage is seperated into degradable and non-degradable wastes as because degradable wastes can be biologiacally degraded or decomposed or dump into pits or yards so that it can help increasing the fertility of the soil and used by the plants.