Also, although nitrification rates of plant P5 were projected to be less than 0.7 mg N/g VSS h at pH 7.0, nitrification, in fact greatly improved, more than tripling to 2.65 mg N/g VSS h with increasing the pH from 7.0 to 8.0. At pH 9.0, all nitrification rates of activated sludge in plants slightly increased with changes in temperature conditions approaching optimal values (25–35 C).