To　explore　the　removal　route　of　ammonia　nitrogen,　a　biological　purification　process　operation　test　for　high　concentration　of　iron　and　manganese　associated　ammonia　nitrogen　[Fe()　9.2-15.1　mg/L,　Mn()　0.6-1.4　mg/L,　NH4+-N　0.9-2.0　mg/L]　was　carried　out　at　low　temperature　(5-6　)　in　a　groundwater　plant　for　iron,　manganese,　and　ammonia　nitrogen　removal.　Results　show　that　the　filter　column　had　good　removal　effect　of　ammonia　nitrogen　at　the　initial　stage　of　start-up.　The　analysis　along　the　process　and　the　adsorption　test　of　mature　filter　material　and　backwash　sludge　show　that　when　the　influent　ammonia　nitrogen　was　about　1.1　mg/L,　the　ammonia　nitrogen　was　mainly　removed　by　the　iron　and　manganese　oxides　in　the　upper　part　of　the　filter　layer,　and　the　removal　rate　by　biological　action　was　very　small.　In　order　to　further　explore　the　biological　and　adsorption　effects　of　filter　column　on　ammonia　nitrogen,　gradient　was　used　to　adjust　the　concentration　of　ammonia　nitrogen　in　influent.　With　the　increase　of　the　influent　ammonia　nitrogen　concentration,　the　ammonia　nitrogen　removal　by　biological　action　increased.　Under　the　condition　of　influent　iron　and　manganese　concentration,　the　ammonia　nitrogen　removal　by　iron　and　manganese　oxides　adsorption　was　about　1　mg/L　in　the　upper　20　cm　range　of　the　filter.　©　2020,　Editorial　Board　of　Journal　of　Harbin　Institute　of　Technology.　All　right　reserved.