Long-term ammonia gas biofiltration through simultaneous nitrification, anammox and denitrification process with limited N2O emission and negligible leachate production

Abstract

Ammonia is toxic and malodorous gas, which is emitted from agricultural and industrial sources. Most of known ammonia gas treatment methods share the disadvantages of expensive cost, by-product pollution and high energy consumption. In this study, an ammonia gas biotreatment method was developed, through simultaneous nitrification, anammox and denitrification process (SNAD) in a biofilter, which was expected to reduce operation cost, secondary pollution and energy consumption. Ammonia gas was converted to di-nitrogen gas (97.2–99.5%) and nitrous oxide (0.5–1.8%), with the highest ammonia loading rate of 0.173 gNH3/gVSS·d. Removed ammonia was taken up by both nitrification (70.6%) and anammox (29.4%) process. Anammox and denitrification process contributed to about 60% and 40% of di-nitrogen gas production in SNAD system, respectively. N2O emission might be caused by nitrification as well as denitrification processes, but not by anammox process in the reactor. TN removal efficiency achieved up to 99.4%, which suggested negligible leachate production in SNAD system for ammonia gas filtration. Anammox activity was not inhibited after introducing oxygen, which was most likely related to activity of oxygen-consuming ammonia oxidation, nitrite oxidation and denitrification. As far as know, this study is the first evidence for ammonia gas biofiltration with anammox-related technology, which might be a highly efficient and cost effective solution for ammonia gas removal with less energy consumption (<30%), biomass production (∼10%), greenhouse gas emission (70–80%) and wastewater production (100%).