Premium
Nitrous Oxide Emissions from Wastewater Treatment and Water Reclamation Plants in Southern California
Author(s) -
TownsendSmall Amy,
Pataki Diane E.,
Tseng Linda Y.,
Tsai ChengYao,
Rosso Diego
Publication year - 2011
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2011.0059
Subject(s) - land reclamation , nitrous oxide , wastewater , environmental science , sewage treatment , waste management , environmental engineering , environmental protection , water resource management , engineering , geography , chemistry , archaeology , organic chemistry
Nitrous oxide (N 2 O) is a long‐lived and potent greenhouse gas produced during microbial nitrification and denitrification. In developed countries, centralized water reclamation plants often use these processes for N removal before effluent is used for irrigation or discharged to surface water, thus making this treatment a potentially large source of N 2 O in urban areas. In the arid but densely populated southwestern United States, water reclamation for irrigation is an important alternative to long‐distance water importation. We measured N 2 O concentrations and fluxes from several wastewater treatment processes in urban southern California. We found that N removal during water reclamation may lead to in situ N 2 O emission rates that are three or more times greater than traditional treatment processes (C oxidation only). In the water reclamation plants tested, N 2 O production was a greater percentage of total N removed (1.2%) than traditional treatment processes (C oxidation only) (0.4%). We also measured stable isotope ratios (δ 15 N and δ 18 O) of emitted N 2 O and found distinct δ 15 N signatures of N 2 O from denitrification (0.0 ± 4.0‰) and nitrification reactors (−24.5 ± 2.2‰), respectively. These isotope data confirm that both nitrification and denitrification contribute to N 2 O emissions within the same treatment plant. Our estimates indicate that N 2 O emissions from biological N removal for water reclamation may be several orders of magnitude greater than N 2 O emissions from agricultural activities in highly urbanized southern California. Our results suggest that wastewater treatment that includes biological nitrogen removal can significantly increase urban N 2 O emissions.