The　development　of　tight　ultrafiltration　membranes　has　opened　new　avenues　for　the　fractionation　of　organics　and　inorganic　salts　from　highly　saline　organic-rich　wastewaters,　showing　great　potential　as　alternatives　to　nanofiltration　membranes　for　the　sustainable　recovery　of　high　value-added　products.　In　this　work,　polypeptide-based　antimicrobial　tight-ultrafiltration　membranes　were　developed　through　the　interfacial　polymerization　of　ε-polylysine　(ε-pl)　and　trimesoyl　chloride　(TMC)　on　porous　ultrafiltration　substrates　for　the　sustainable　management　of　highly　saline　textile　wastewater.　Systematic　characterization　was　conducted　to　demonstrate　the　formation　of　continuous,　thin　and　smooth　ε-pl/TMC　cross-linked　networks.　The　designed　tight　ε-pl/TMC　composite　ultrafiltration　membrane　with　a　MWCO　of　3185　Da　showed　exceptional　dye/salt　fractionation　performance　in　highly　saline　textile　wastewater,　achieving　＞99.80　%　rejection　for　various　dyes　(0.2　g　L−1　direct　red　80,　reactive　black　5　or　reactive　blue　2)　and　a　＜3.35　%　salt　rejection　(20.0　g　L−1　NaCl),　with　favorable　water　permeation　(39.13–44.46　L　m−2　h−1·bar−1).　In　addition,　the　long-term　stability　of　the　polypeptide-based　tight　ultrafiltration　membrane　was　confirmed　to　be　sufficient　for　enduring　dye/salt　separation.　Furthermore,　the　intercalation　of　ε-polylysine　onto　the　membrane　surface　strongly　enhanced　the　antibacterial　activity　(i.e.,　99.97　%　bacterial　inhibition)　of　the　tight　ultrafiltration　membranes.　This　competitive　performance　highlights　the　potential　of　tight　ε-pl/TMC　composite　ultrafiltration　membranes　for　the　sustainable　management　of　highly　saline　organic　wastewater.　©　2025