the amount of oxidant injected in each port is effective to reduce the content of organic matter in {TAIL ~ the stream} by {HEAD ~ a predetermined amount} in the primary stream, and 
the amount of oxidant injected in each port is effective to reduce the content of organic matter in { TAIL ~ the stream } by { HEAD ~ a predetermined amount } in the primary stream , and
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH