Concepts and Comments
The question here is "Can we use a strainer to separate cells from medium?" The idea being to eliminate a centrifugation step when exchanging to sulfur free medium. Ideas for strainers are a fine screen or mesh or even a microporous filter, such as a membrane.
Another possibility to test for separating cells from medium is settling. If circulation is turned off, will cells settle enough to where the medium can be carefully drained off?