The present invention describes a process for converting vapor streams from sources containing at least one
nitrogen-containing
oxidizing agent therein to a liquid
fertilizer composition comprising the steps of: a) directing a vapor
stream containing at least one
nitrogen-containing
oxidizing agent to a first
contact zone, b) contacting said vapor
stream with water to form
nitrogen oxide(s) from said at least one nitrogen-containing
oxidizing agent, c) directing said acid(s) as a second
stream to a second
contact zone, d) exposing said second stream to
hydrogen peroxide which is present within said second
contact zone in a relative amount of at least 0.1% by weight of said second stream within said second contact zone to convert at least some of any
nitrogen oxide species or ions other than in the
nitrate form present within said second stream to
nitrate ion, e) sampling said stream within said second contact zone to determine the relative amount of
hydrogen peroxide within said second contact zone, f) adding
hydrogen peroxide to said second contact zone when a level of
hydrogen peroxide less than 0.1 % by weight in said second stream is determined by said sampling, g) adding a solution comprising
potassium hydroxide to said second stream to maintain a pH between 6.0 and 11.0 within said second stream within said second contact zone to form a solution of
potassium nitrate, and h) removing said solution of
potassium nitrate from said second contact zone.