Biodegradable waste is the waste that can be recycled.Biodegradable waste is not harmful for nature.For examples 

1. Paper
2. Leaves
3. Plants
4. Cardboard

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Everything which nature can recycle on its own is biodegradable waste.All biodegradable waste are recycled and reused in some form or another. eg: old vegetables / food, paper, cardboard etc.. 
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