The water and gas delivery rates are controlled to satisfy the following relations: ##EQU1## wherein {HEAD ~ Q1} is the delivery of {TAIL ~ oxygenated gas} in m3 /hr, 
The water and gas delivery rates are controlled to satisfy the following relations : # # EQU1 # # wherein { HEAD ~ Q1 } is the delivery of { TAIL ~ oxygenated gas } in m3 /hr ,
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH