Is it possible to efficiently create a bloom filter with 10^12 buckets on a single machine with 32GB of RAM and a hard drive. We can assume that the keys are already on the disk and are small in size?
A Bloom filter doesn't have "buckets".
You can make a Bloom filter of any size you want. The smaller it is, the higher the false positive rate.
This should be covered in any good introduction to Bloom filters, of which there are many.