Sustainable　treatment　of　the　highly　saline　landfill　leachate　concentrate　for　application　as　green　fertilizer　calls　for　effective　fractionation　of　the　existing　humic　substances　and　inorganic　salts;　advanced　selective　nanofiltration　membranes　are　proposed　for　this.　One-step,　rapid　assembly　of　a　tannic　acid-Fe3+　coordination　complex　is　a　promising　strategy　to　endow　the　membranes　with　an　enhanced　nanofiltration　performance.　In　this　study,　a　robust　and　homogeneous　tannic　acid-Fe3+　coordination　complex　layer　was　effectively　coated　onto　the　surface　of　a　loose　nanofiltration　substrate　in　an　extremely　short　time　(15　s).　After　the　coating　of　the　tannic　acid-Fe3+　coordination　complex　layer,　the　nanofiltration　membrane　showed　a　significantly　reduced　molecule　weight　cutoff　(i.e.,　reduction　from　601　to　279　Da)　and　thus　enhanced　selectivity　towards　humic　substances.　Specifically,　the　rejection　to　humic　substances　of　the　coated　nanofiltration　membrane　increased　from　95.31±0.54%　to　99.32±0.18%　with　negligible　rise　in　salt　rejection,　demonstrating　an　enhanced　fractionation　efficacy　for　humic　substances　and　salts.　Assisted　by　a　diafiltration　operation　with　the　coated　nanofiltration　membrane,　humic　substances　in　the　landfill　leachate　concentrate　were　effectively　purified　and　extracted　with　96.60%　recovery.　Particularly,　the　humic　substances　were　linearly　enriched　by　ca.　7.8　folds　(i.e.,　from　1837　to　13970　mg·L−1)　with　a　purity　of　98.91%　for　potential　application　as　liquid　fertilizer.　The　one-step　rapid　tannic　acid-Fe3+　coordination　complex　coating　exhibits　an　impressive　efficacy　to　engineer　advanced　nanofiltration　membranes　that　could　be　applied　at　a　large　scale　for　sustainable　resource　extraction　from　landfill　leachate　concentrate.　©　2021