In {TAIL ~ Step} 23, {HEAD ~ the pumping} of the solution and the discharging of the liquid are controlled to optimum rates 
In
In { TAIL ~ Step } 23 , { HEAD ~ the pumping } of the solution and the discharging of the liquid are controlled to optimum rates
REL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH