This　study　demonstrated　the　excellent　di-(2-ethylhexyl)　phthalate　(DEHP)　removal　performance　of　a　pre-denitrification　biofilter　system.　Experimental　results　showed　that　DEHP　removal　efficiency　remained　stable　while　total　nitrogen　removal　efficiency　fluctuated　with　the　nitrate　recycle　ratio　changes　when　the　hydraulic　loading　rate　at　1.1　m(3)/m(2)　h.　DEHP　removal　efficiency　increased　from　48%　to　82%　while　the　hydraulic　loading　rate　increased　from　1.1　to　2.2　m(3)/m(2)　h.　DEHP　concentration　decreased　gradually　along　the　wastewater　flow　direction　in　the　denitrification　biofilter　and　a　plug　flow　model　with　the　reaction　order　of　5　and　the　rate　constant　of　0.54　was　obtained.　Both　the　denitrification　biofilter　and　the　nitrification　biofilter　showed　similar　DEHP　removal　performance.　The　overall　DEHP　removal　efficiency　of　the　system　was　83.8%,　in　which　biodegradation　contributed　72.3%.　Biodegradation　plays　a　key　role　in　DEHP　removal　in　the　pre-denitrification　biofilter　system.　(C)　2014　Elsevier　Ltd.　All　rights　reserved.