{TAIL ~ The reactor} is {HEAD ~ a bubble/particle contacting device} where collection takes place while bubbles are being formed 
{ TAIL ~ The reactor } is { HEAD ~ a bubble / particle contacting device } where collection takes place while bubbles are being formed
TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH