Simultaneous　bio-treatment　processes　of　organic　carbon　(C)-,　nitrogen　(N)-,　and　phosphorus　(P)-containing　wastewater　are　challenged　by　insufficient　carbon　sources　in　the　effluent.　In　the　present　study,　two　parallel　anaerobic/aerobic　sequencing　batch　reactors　(R-1　and　R-2)　treating　low　C/N　(＜　4)　wastewater　were　employed　using　different　partial　nitrification　start-up　strategies,　controlled　reduced　aeration,　and　decreased　sludge　retention　time.　Advanced　removal　efficiencies　for　NH4+-N　(＞=　96%),　total　nitrogen　(TN,　＞=　86%),　PO43-　-P　(＞=　95%),　and　CODintra　(＞=　91%)　were　realized,　with　TN　and　PO43-　-P　effluent　concentrations　of　10.0　+/-　3.5　and　0.11　+/-　0.3　mg/L　in　R-1　and　9.28　+/-　4.0　and　0.11　+/-　0.1　mg/L　in　R-2,　respectively.　Higher　nitrite　accumulation　rate　(nearly　100%)　and　TN　(121.1　+/-　0.7　mg　TN/g　VSS.d)　and　P　(12.5　+/-　0.6　mg　PO43-　-P/g　VSS.d)　removal　loadings　were　obtained　in　R-2　by　a　thorough　elimination　of　nitrite-oxidizing　bacteria.　Moreover,　different　microbial　structures　and　nutrient　removal　pathways　were　identified.　Denitrifying　glycogen-accumulating　organisms　(Candidatus　Competibacter)　and　phosphorus-accumulating　organisms　(PAOs)　(Tetrasphaera)　removed　N　and　P　with　partial　nitrification-endogenous　denitrification　pathways　and　aerobic　P　removal　in　R-1.　In　R-2,　aerobic　denitrifying　bacteria　(Psychrobacter)　and　PAOs　ensured　N　and　P　removal　through　the　partial　nitrification-aerobic　denitrification　and　aerobic　P　removal　pathways.　Compared　to　R-1,　R-2　offers　greater　efficiency,　convenience,　and　scope　to　further　reduce　carbon-source　demand.