Open AccessModelling the N2O Emissions in Municipal Wastewater Treatment Plants under Dynamic Conditions
Author(s) -
Theoni Maria Massara,
Borja Solís Duran,
Albert Guisasola,
Evina Katsou,
Juán Antonio Baeza
Publication year - 2018
Publication title -
epic series in engineering
Language(s) - English
Resource type - Conference proceedings
ISSN - 2516-2330
DOI - 10.29007/w6rq
Subject(s) - denitrification , nitrification , nitrous oxide , anoxic waters , environmental science , aerobic denitrification , activated sludge model , sewage treatment , greenhouse gas , environmental engineering , activated sludge , environmental chemistry , chemistry , nitrogen , denitrifying bacteria , ecology , biology , organic chemistry
Nitrous oxide (N2O), a greenhouse gas with a significant global warming potential, can be produced during the biological nutrient removal in wastewater treatment plants (WWTPs). N2O modelling under dynamic conditions is of vital importance for its mitigation. Following the activated sludge models (ASM) layout, an ASM-type model was developed considering three biological N2O production pathways for a municipal anaerobic/anoxic/aerobic (A2/O) WWTP performing chemical oxygen demand, nitrogen and phosphorus removal. Precisely, the N2O production pathways included were: nitrifier denitrification, hydroxylamine oxidation, and heterotrophic denitrification, with the first two linked to the ammonia oxidizing bacteria (AOB) activity. A stripping effectivity (SE) factor was used to mark the non-ideality of the stripping modelling. With the dissolved oxygen (DO) in the aerobic compartment ranging from 1.8 to 2.5 mg L-1, partial nitrification and high N2O production via nitrifier denitrification occurred. Therefore, low aeration strategies can effectively lead to a low overall carbon footprint only if complete nitrification is guaranteed. After suddenly increasing the influent ammonium load, the AOB had a greater growth compared to the NOB. N2O hotspot was again nitrifier denitrification. Especially under concurring partial nitrification and high stripping (i.e. combination of low DO and high SEs), the highest N2O emission factors were noted.