The　feasibility　of　bio-augmentation　processes　in　promoting　start-up　of　partial　nitrification　of　sewage　was　investigated　in　this　study.　Initially,　partial　nitrification　was　well-established　in　an　anoxic/oxic　reactor　treating　high-strength　ammonia　wastewater.　Then　the　influent　was　replaced　by　real　sewage　instantly　or　gradually.　In　both　cases,　nitrite　pathway　could　be　maintained　for　5-7　d.　However,　it　was　eventually　destroyed　due　to　the　inevitable　over-aeration.　In　another　strategy,　sewage　was　treated　in　the　adsorption/biodegradation　reactor.　The　nitrite　pathway　was　obviously　promoted　by　addition　of　the　previous　activated　sludge　from　high　ammonia　wastewater　treatment.　Nitrite　accumulation　efficiency　of　sewage　was　quickly　increased　from　26%　to　86%　and　maintained　at　a　high　level　for　2　months.　Moreover,　the　effluent　has　a　favorable　ratio　of　NH4+/NO2-　for　feeding　anammox　process.　The　experimental　results　indicated　that　appropriate　bio-augmentation　strategies　could　significantly　improve　the　build-up　partial　nitrification　of　sewage　in　the　pretreatment　of　anammox.　(C)　2012　Elsevier　Ltd.　All　rights　reserved.