Limited　filamentous　bulking　(LFB)　activated　sludge　process　was　proposed　by　Guo　et　al.　(2010)　to　increase　the　removal　of　tiny　suspended　particulates　in　the　clarifier　and　reduce　aeration　energy　consumption.　However,　when　the　use　of　LFB　process,　ammonium　removal　efficiency　would　be　compromised　due　to　low　dissolved　oxygen　(DO).　In　this　study,　the　combination　process　of　nitrogen　removal　via　nitrite　and　LFB　was　achieved　to　enhance　nitrogen　removal　and　reduce　aeration　energy　consumption　by　controlling　low　DO　levels　(0.5-1.0　mg　L-1)　in　a　lab-scale　anoxic-oxic　reactor　(V　=　66　L)　treating　real　domestic　wastewater　at　room　temperature.　Above　85%　of　nitrite　accumulation　ratio　was　steadily　maintained　during　continuous　operation　period.　The　combined　process　improved　the　total　nitrogen　(TN)　removal　by　about　20%　in　comparison　to　the　traditional　process　via　the　nitrate　pathway,　and　also　reduced　the　specific　aeration　energy　consumption　by　35%.　COD,　ammonium　and　TN　removal　efficiencies　were　up　to　86%,　94%　and　75%,　respectively.　The　process　proved　effective　in　achieving　a　steady　LFB　state,　whereby　sludge　volume　index　between　150　and　250　mL　g(-1)　was　sustained　for　long-term　operation.　The　microbial　community　structure　was　analyzed　by　fluorescence　in　situ　hybridization,　which　indicated　ammonia-oxidizing　bacteria　out-competed　nitrite-oxidizing　bacteria.　Moreover,　the　filaments　Type　0041　and　Microthrix　parvicella　proliferated　with　limited　abundance.　The　results　indicated　the　combination　process　of　LFB　and　nitrogen　removal　via　nitrite　under　low　DO　was　a　feasible　solution　for　saving　energy　and　enhancing　nitrogen　removal　when　treating　domestic　wastewater.　Crown　Copyright　(c)　2012　Published　by　Elsevier　Ltd.　All　rights　reserved.