With　the　increasing　application　of　anammox　for　the　treatment　of　high-strength　industrial　wastewater,　application　of　anammox　in　municipal　sewage　has　been　gaining　more　attention.　Sludge　granulation　in　particular　enhances　the　enrichment　and　retention　of　anammox　bacteria　in　municipal　sewage　treatment　systems.　However,　the　performance　of　granular　sludge　under　continuous　and　varying　hydraulic　loading　shock　remains　little　understood.　In　this　study,　the　robustness　of　anammox　granular　sludge　in　treating　low-strength　municipal　sewage　under　various　shock　loadings　was　investigated.　Results　showed　that　an　upflow　anaerobic　sludge　blanket　(UASB)　reactor　with　anammox　granules　performed　well,　with　anammox　specific　activity　up　to　0.28　kg　N/kg　VSS/day　and　anti-loading　shock　capability　up　to　187.2　L/day　during　the　8-month　testing　period.　The　accumulation　rate　of　N2O　(＜　0.01　kg　N/kg　VSS/day)　in　the　liquid　phase　was　seven　times　higher　than　that　of　the　gas　phase,　which　could　be　mainly　attributed　to　the　incomplete　denitrification　and　insufficient　carbon　source.　However,　only　a　small　part　of　the　produced　N2O　escaped　into　the　atmosphere.　High-throughput　sequencing　and　molecular　ecological　network　analyses　also　identified　the　bacterial　diversity　and　community　structure,　indicating　the　potential　resistance　against　loading　shock.　The　composition　and　structural　analyses　showed　that　polysaccharides　were　an　important　functional　component　in　the　tightly　bound　extracellular　polymeric　substances　(TB-EPS),　which　was　the　major　EPS　layer　of　anammox　granules.　Scanning　electron　microscopy　(SEM)　also　showed　that　the　gaps　in　between　the　anammox-clusters　in　the　granules　inhibit　the　flotation　of　the　sludge　and　ensure　efficient　settling　and　retention　of　anammox　granules.　(c)　2019　The　Research　Center　for　Eco-Environmental　Sciences,　Chinese　Academy　of　Sciences.　Published　by　Elsevier　B.V.