Reversed Vending Machine with database as backup system

My project is a Reversed Vending Machine. There will be a storage that will store used plastic bottles. But the the storage should only accept the plastic bottles if they are empty (no liquid inside or any) .

If you drop a 1kg of plastic bottles, the storage should give the a corresponding coin value or rfid card credit point. The customer will decide whether he wants to store his points in his rfid card or get it immediately as a coins. And then all the informations such as credit points which is in rfid cards should be backed up by a database in case the rfid card is lost or ruined.

The points in rfid card should be swapped into coins as well through swiping of that card