Abstract
Presence of anaerobic ammonium oxidation (anammox) process was investigated in low ammonium-fed solid-phase denitrification bioreactor. A promising application of solid substrates for denitrification has been appeared since last decade and this type of denitrification here termed as solid-phase denitrification. Bioreactor was operated for 300 days in a temperature-controlled incubator. An immobilized biomass of activated sludge and anaerobic granules was used as inocula in the bioreactor and solid biodegradable plastic as a carbon source. Nitrogen mass balance showed that the average nitrogen removal efficiency in the bioreactor was 80%. The combined results of nutrient profiles, 15N-labelling techniques and qualitative fluorescence in situ hybridization (FISH) probe confirmed that anammox bacteria were active in the bioreactor. This clearly demonstrates that both anammox and denitrification processes work symbiotically in low ammonium concentrations under the support of solid substrates. It revealed that solid substrates not only serve as constant sources of reducing power for denitrification but also creates the favourable condition for anammox process by utilizing dissolved oxygen during the degradation of solid substrates.
