Biscuit packets usually contain two different types of plastic, the tray and the soft and scrunchy wrapping.
The tray can be recycled through your kerbside recycling bin but the soft scrunchy plastic wrapper cannot.
The soft scrunchy wrapper should be put aside with your other soft plastics to be taken to your a REDcycle bin at participating supermarkets.
Click here to find your nearest REDcycle bin https://www.redcycle.net.au/where-to-redcycle/
If you cannot take your soft scrunchy biscuit wrappers to a REDcycle bin they should be placed in your general waste bin to be sent to landfill.