The paper presents results of study of anoxic ammonia oxidation at low temperature conducted at JSC Mosvodokanal, Moscow, Russia. The study was carried out in two reactors, 5 l each, operated at the temperature of 5–10 °С. Both reactors were inoculated with the soil, collected from waste water sludge landfill, that presumably, contained low-temperature adapted nitrifying bacteria. Reactor No. 1 contained nitrifying bacteria only. Reactor No. 2 was further inoculated by anammox bacteria. Filtrate from digested sludge belt thickeners was added into the reactors to achieve a final N-NH4 concentration of 70–95 mg/l. The reactors were operated as sequencing batch reactors. After 90 days of incubation maximal nitrification rate in reactor No. 1 was 1.4 mg N-NH4/g VSS*h, and in reactor No. 2–1.0 mg N-NH4/g VSS*h. Estimated doubling time of nitrifying bacteria was 45 days. Total mineral nitrogen removal in the 1st reactor was 20% (via process of heterotrophic denitrification), and in the 2nd – 60% (via both the processes of heterotrophic and autotrophic nitrate reduction). Through the process of autotrophic denitrification (anammox), two times as much nitrogen was removed, compared to the heterotrophic denitrification process. Anammox process rate was 0.4 mg N-NH4/g VSS*h.

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