Presently,　the　wastewater　treatment　practices　can　be　significantly　improved　through　the　introduction　of　new　microbial　treatment　technologies.　To　meet　increasingly　stringent　discharge　standards,　new　applications　and　control　strategies　for　the　sustainable　removal　of　ammonium　from　wastewater　have　to　be　implemented.　Partial　nitrification　to　nitrite　was　reported　to　be　technically　feasible　and　economically　favorable,　especially　when　wastewater　with　high　ammonium　concentrations　or　low　C/N　ratios　is　treated.　For　successful　implementation　of　the　technology,　the　critical　point　is　how　to　maintain　partial　nitrification　of　ammonium　to　nitrite.　Partial　nitrification　can　be　obtained　by　selectively　inhibiting　nitrite　oxidizing　bacteria　through　appropriate　regulation　of　the　system＇s　DO　concentration,　microbial　SRT,　pH,　temperature,　substrate　concentration　and　load,　operational　and　aeration　pattern,　and　inhibitor.　The　review　addressed　the　microbiology,　its　consequences　for　their　application,　the　current　status　regarding　application,　and　the　future　developments.