Achieving　sustainable　partial　nitrification　to　nitrite　has　been　proven　difficult　in　treating　low　strength　nitrogenous　wastewater.　Real-time　aeration　duration　control　was　used　to　achieve　efficient　partial　nitrification　to　nitrite　in　a　sequencing　batch　reactor　(SBR)　to　treat　low　strength　domestic　wastewater.　Above　90%　nitrite　accumulation　ratio　was　maintained　for　long-term　operation　at　normal　condition,　or　even　lower　water　temperature　in　winter.　Partial　nitrification　established　by　controlling　aeration　duration　showed　good　performance　and　robustness　even　though　encountering　long-term　extended　aeration　and　starvation　period.　Process　control　enhanced　the　successful　accumulation　of　ammonia　oxidizing　bacteria　(AOB)　and　washout　of　nitrite　oxidizing　bacteria　(NOB).　Scanning　electron　microscope　observations　indicated　that　the　microbial　morphology　showed　a　shift　towards　small　rod-shaped　clusters.　Fluorescence　in　situ　hybridization　(FISH)　results　demonstrated　AOB　were　the　dominant　nitrifying　bacteria,　up　to　8.3　+/-　1.1%　of　the　total　bacteria;　on　the　contrary,　the　density　of　NOB　decreased　to　be　negligible　after　135　days　operation　since　adopting　process　control.　(C)　2009　Published　by　Elsevier　Ltd.