The recycle bin was quietly introduced in Oracle 10g as a method to have flashback drop functionality. It comes in handy, but generally not in production databases, most of the use is in development. By default the recycle bin is operating, this can be a problem when you go to list, export or drop all the tables in a schema because there may be a whole bunch with BIN$blahblahblah in there. There are the objects that have been added to the recycle bin. The object dropped still takes up its original space, it is recreated it takes new extents. If this happens over and over again, you could potentially run out of space and not know why unless you check the contents of the recycle bin with:

SQL> select * from user_recyclebin;

If you wish to purge all of the objects you can use the command

SQL> purge recyclebin;

This command will purge all the objects out of the current user’s recycle bin. If you want to purge all objects out of the recycle bin, login as a dba user and execute:

SQL> purge dba_recyclebin;

To shut off the recycle bin depends on the version:

10gR1 - SQL> alter system set "_recyclebin"=false scope=both;
10gR2 & 11g - SQL> alter system set recyclebin = off;

For more information see Metalink note 264253.1.