{HEAD ~ Tailings} are recycled back into {TAIL ~ the reactor} and combined with fresh feed for bubble control 
{ HEAD ~ Tailings } are recycled back into { TAIL ~ the reactor } and combined with fresh feed for bubble control
HEAD HEAD HEAD HEAD HEAD REL REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH