Question

why dustbin are categorized in different types and what is the colour?

Answer 1

just because to keep ,biodegradable&nonbiodegradble waste different.
many of them cam be recyclable

Answer 2

Dustbins are categorized in different colours so that biodegradable and non-biodegradable waste could be easily separated out for better garbage collection as well as for disposal and to make sure that bio waste does not combine with non- biodegradable waste as it could be harmful.

Blue dustbin is for non- biodegradable waste and

Green dustbin is for biodegradable waste