Cell　immobilization　was　used　to　enrich　and　retain　functional　bacteria　within　partial　denitrification-Anammox　(PD/A)　process　to　achieve　its　fast　start-up　for　the　first　time.　To　do　so,　residue　sludge　and　Anammox　sludge　were　immobilized　in　poly　(vinyl　alcohol)/sodium　alginate　(PVA/SA)　gel　for　PD　cultivation　and　Anammox　bacteria　inoculation,　respectively.　Stable　PD　with　NO3--N　to　NO2--N　transformation　ratio　(NTR)　of　72.0%　was　achieved　within　13 days　at　25 °C　and　successfully　combined　with　Anammox　on　14th　day.　The　hydrous　porous　PVA/SA　gel　matrix　played　the　role　of　extracellular　polymeric　substance　(EPS)　and　thus　protected　the　microbes　against　low　temperature.　Satisfactory　nitrogen　removal　rate　(NRR)　(301.6 ± 6.1 g N/(m3·d))　was　achieved　even　when　temperature　decreased　to　13 °C.　The　contribution　of　nitrogen　removal　via　Anammox　was　as　high　as　77.10%.　Abundance　of　Thauera　and　Candidatus　Kuenenia　increased　from　0.9%　and　1.1%　to　30.6%　and　2.1%,　respectively.