Immobilized　microorganism　technology　has　attracted　increasing　attention　for　high　concentration　of　microbes,　low　cell　loss　and　high　resistance　to　impact　of　environment.　The　microbial　reduction　of　nitrate　in　the　presence　of　sediment-based　biochar　(SBC)　and　nanoscale　zero-valent　iron　(nZVI)　was　investigated　in　four　different　free　systems.　NZVI-SBC/bacteria　system　realized　the　best　nitrate　removal　of　97.61%　within　3　days　through　the　synergistic　effect　of　SBC　and　nZVI　on　denitrifying　bacteria.　Accumulation　of　nitrite　and　ammonium　in　nZVI-SBC/　bacteria　system　also　decreased.　High-throughput　sequencing　results　showed　that　the　proportion　of　denitrifying　bacteria　in　microbial　community　structure　increased　after　adding　nZVI-SBC.　The　performance　of　nitrate　removal　was　then　studied　through　PVA/SA-immobilization.　Immobilized　active　pellets　performed　better　nitrate　removal　(98.89%)　and　stronger　tolerance　under　different　conditions　than　the　free　bacterial　cells.　Overall,　this　study　provided　a　promising　approach　by　utilizing　SBC　and　nZVI　for　the　bio-remediation　of　nitrate-contaminated　water　in　practical　application.