A few ways to find and get rid of NULL bites in documents.

purge-null

tr < file-with-nulls -d '\000' > file-without-nulls

sed 's/\x0//g' file-with-nulls > file-without-nulls

sed 's/\x0/ /g' file-with-nulls > file-without-nulls

grep -P '\000' < file-with-nulls >file-without-nulls

awk '/\000/ { print }'

perl -ne 'print if m/\000/'

# python
f = open('file-with-nulls')
for l in f.readlines():
  print l.replace("\0", '')