Wipe the first 1GB

# dd if=/dev/zero of=/dev/sdX bs=1M count=1024

Wipe the last 1MB

Some RAID configuration data might be present at the end of the disk, thus existing the need to delete this data, before reusing the disk

# dd bs=1M if=/dev/zero of=/dev/sdX count=1024 seek=$((`blockdev --getsz /dev/sdX` - 1024))