Conventional　immobilized　nitrifying　bacteria　technologies　are　limited　to　fixed　beds　with　regular　shapes　such　as　spheres　and　cubes.　To　achieve　a　higher　mass　transfer　capacity,　a　complex-structured　cultivate　bed　with　larger　specific　surface　areas　is　usually　expected.　Direct　ink　writing　(DIW)　3D　printing　technology　is　capable　of　preparing　fixed　beds　where　nitrifying　bacteria　are　embedded　in　without　geometry　limitations.　Nevertheless,　conventional　bacterial　carrier　materials　for　sewage　treatment　tend　to　easily　collapse　during　printing　procedures.　Here,　we　developed　a　novel　biocompatible　waterborne　polyurethane　acrylate　(WPUA)　with　favorable　mechanical　properties　synthesized　by　introducing　amino　acids.　End-capped　by　hydroxyethyl　acrylate　and　mixed　with　sodium　alginate　(SA),　a　dual　stimuli-responsive　ink　for　DIW　3D　printers　was　prepared.　A　robust　and　insoluble　crosslinking　network　was　formed　by　UV-curing　and　ion-exchange　curing.　This　dual-cured　network　with　a　higher　crosslinking　density　provides　better　recyclability　and　protection　for　cryogenic　preservation.　The　corresponding　results　show　that　the　nitrification　efficiency　for　printed　bioreactors　reached　99.9%　in　72　h,　which　is　faster　than　unprinted　samples　and　unmodified　WPUA　samples.　This　work　provides　an　innovative　immobilization　method　for　3D　printing　bacterial　active　structures　and　has　high　potential　for　future　sewage　treatment.