A method for partial removal of nitrogen oxide contaminants from a process gas stream comprising the steps of: conveying a process gas stream through a duct manifold from a combustion process, separating the process gas stream in the duct manifold into three separate process gas streams, feeding an ozone containing gas stream into the duct manifold via respective one or two separate nozzles depending on nitrogen oxide contaminant content and partial removal required into one or two of the separated three process gas streams to oxidize the nitrogen oxide contaminants to respectively form one or two oxidized portions of process gas streams, feeding the one or two oxidized portions and the respectively remaining one or two ozone free portions of the process gas streams to a scrubber for removal of the oxidized nitrogen oxide contaminants, wherein the scrubber is partitioned into three chambers to receive in one or two of the chambers respectively the one or two oxidized portions of the process gas streams and to receive in the remaining one or two chambers of the scrubber respectively the one or two ozone free portions of the process gas streams, contacting the one or two oxidized portions of the process gas streams respectively with an aqueous scrubbing medium sprayed into the scrubber using an array of spray nozzles in each chamber to remove the oxidized nitrogen oxide contaminants from the one or two oxidized portions of the process gas streams, capturing the oxidized nitrogen oxide contaminants removed from the one or two oxidized portions of the process gas streams, and thereafter unifying the one or two oxidized portions of the process gas streams free of nitrogen oxide contaminants with the respective remaining one or two ozone free portions of the process gas stream containing nitrogen oxide contaminants to form the treated process gas stream with partially removed nitrogen oxide contaminants. conveying a process gas stream through a duct manifold from a combustion process, separating the process gas stream in the duct manifold into three separate process gas streams, feeding an ozone containing gas stream into the duct manifold via respective one or two separate nozzles depending on nitrogen oxide contaminant content and partial removal required into one or two of the separated three process gas streams to oxidize the nitrogen oxide contaminants to respectively form one or two oxidized portions of process gas streams, feeding the one or two oxidized portions and the respectively remaining one or two ozone free portions of the process gas streams to a scrubber for removal of the oxidized nitrogen oxide contaminants, wherein the scrubber is partitioned into three chambers to receive in one or two of the chambers respectively the one or two oxidized portions of the process gas streams and to receive in the remaining one or two chambers of the scrubber respectively the one or two ozone free portions of the process gas streams, contacting the one or two oxidized portions of the process gas streams respectively with an aqueous scrubbing medium sprayed into the scrubber using an array of spray nozzles in each chamber to remove the oxidized nitrogen oxide contaminants from the one or two oxidized portions of the process gas streams, capturing the oxidized nitrogen oxide contaminants removed from the one or two oxidized portions of the process gas streams, and thereafter unifying the one or two oxidized portions of the process gas streams free of nitrogen oxide contaminants with the respective remaining one or two ozone free portions of the process gas stream containing nitrogen oxide contaminants to form the treated process gas stream with partially removed nitrogen oxide contaminants.