“…Consequently, full-scale implementation of heterotrophic denitrification is still guided by a somewhat empirical understanding of its microbial ecology and biokinetics, which in turn limits efforts to optimize denitrification reactor design, monitoring and modeling. Although biokinetic parameters for methylotrophic denitrification in activated sludge have been extensively reported (dos Santos et al, 2004;Gauntlett, 1979;Her and Huang, 1995;Janning et al, 1995;Lee and Welander, 1996;Louzeiro et al, 2002;Mulcahy et al, 1981;Purtschert and Gujer, 1999), the actual abundance and diversity of organisms in activated sludge that actually metabolize methanol and alternate carbon and electron sources has only recently been identified (Ginige et al, 2004(Ginige et al, , 2005Osaka et al, 2006Osaka et al, , 2008. The reason for such sparse data on the identity of bacterial populations denitrifying using specific electron donors is that unlike nitrifying bacteria, which are phylogenetically closely related (Purkhold et al, 2000), denitrifying bacteria are distributed widely across taxonomic groups (Zumft, 1997).…”