Dialkyldimethyl　ammonium　compound　(DADMAC)　is　widely　used　in　daily　life　as　a　typical　disinfectant　and　often　co-exists　with　the　heavy　metal　zinc　in　sewage　environments.　This　study　investigated　the　effects　of　co-exposure　to　zinc　(1　mg/L)　and　DADMAC　(0.2–5　mg/L)　on　the　performance,　bacterial　community,　and　resistance　genes　(RGs)　in　a　partial　sulfur　autotrophic　denitrification　coupled　with　anaerobic　ammonium　oxidation　(PSAD-Anammox)　system　in　a　sequencing　batch　moving　bed　biofilm　reactor　for　150　days.　Co-exposure　to　zinc　and　low　concentration　(0.2　mg/L)　DADMAC　did　not　affect　the　nitrogen　removal　ability　of　the　PASD-Anammox　system,　but　increased　the　abundance　and　transmission　risk　of　free　RGs　in　water.　Co-exposure　to　zinc　and　medium-to-high　(2–5　mg/L)　DADMAC　led　to　fluctuations　in　and　inhibition　of　nitrogen　removal,　which　might　be　related　to　the　enrichment　of　heterotrophic　denitrifying　bacteria　dominated　by　Denitratisoma.　Co-exposure　to　zinc　and　high　concentration　DADMAC　(5　mg/L)　stimulated　the　secretion　of　extracellular　polymeric　substances　and　increased　the　proliferation　risk　of　intracellular　RGs　in　sludge.　This　study　provided　insights　into　the　application　of　PSAD-Anammox　system　and　the　ecological　risks　of　wastewater　containing　zinc　and　DADMAC.　©　2024　Elsevier　B.V.