Under　transient　conditions,　a　biotrickling　filter　was　developed　to　treat　gaseous　H2S　produced　from　the　fine-grid　reservoir　of　a　municipal　wastewater　treatment　plant　(WWTP)　with　AAO　excess　sludge　as　the　inoculum　and　polypropylene　rings　as　the　packing　material.　The　start-up　process　and　steady-state　operation　of　the　biotrickling　filter　were　studied.　With　an　empty　bed　retention　time　of　14　s,　an　ambient　temperature　of　7.8-32.5,　and　an　inlet　concentration　of　2.02-319.19　mg•m-3,　an　average　removal　efficiency　of　91.8%　was　achieved　with　a　maximum　H2S　elimination　capacity　of　78.37　g•(m3•h)-1.　Over　a　247-day　period,　the　pressure　drop　across　the　biotrickling　filter　was　maintained　at　96　Pa•m-1.　Microbial　analysis　using　high-throughput　sequencing　technology　showed　a　variation　in　the　microbial　community　during　the　experiment;　the　Shannon　index　dropped　from　4.99　to　3.75,　and　the　functional　genera　Pseudomonas　and　Thiobacillus　were　identified　as　good　performers　in　the　biotrickling　filter　system.　These　results　indicate　that　the　application　of　AAO　excess　sludge　as　an　inoculum　for　biotrickling　filters　is　feasible　for　effective　H2S　removal.　A　steady　pressure　drop　was　achieved　using　polypropylene　rings　as　the　packing　material.　The　diversity　of　the　microbial　community　showed　a　downward　trend　when　exposed　to　H2S,　but　the　elimination　capacity　could　be　increased.　©　2019,　Science　Press.　All　right　reserved.