title: Assessment of N2O emission from a photobioreactor treating ammonia-rich swine wastewater digestate.
abstract: This study investigated the interactions between naturally occurring bacteria and the microalgae Chlorella vulgaris within a lab scale photobioreactor treating ammonia-rich swine wastewater digestate effluent. Nitrification and denitrification were assessed by targeting ammonia monoxygenases (amoA), nitrate (narG), nitrite (nirS), nitric oxide (norB) and nitrous oxide (nosZ) reductases genes. Oxygen produced from microalgae photosynthesis stimulated nitrification. Under limiting carbon availability (i.e., <1.44 for mg TOC/mg NO2-N and 1.72 for mg TOC/mg NO3-N), incomplete denitrification led to accumulation of NO2 and NO3. Significant N2O emission (up to 118 μg N2O-N) was linked to NO2 metabolism in Chlorella. The addition of acetate as external carbon source recovered heterotrophic denitrification activity suppressing N2O emission. Effluent methane concentrations trapped within photobioreactor was removed concomitantly with ammonia. Overall, closed photobioreactors can be built to effectively remove nitrogen and mitigate simultaneously greenhouse gases emissions that would occur otherwise in open microalgae-based wastewater treatment systems.
authors.affiliation: Department of Chemical Engineering, Federal University of Santa Catarina, Florianópolis, SC 88040-900, Brazil. Electronic address: mmezzari@gmail.com.
authors.forename: Melissa P
authors.initials: MP
authors.lastname: Mezzari
authors.forename: Márcio L B
authors.initials: ML
authors.lastname: da Silva
authors.forename: Rodrigo S
authors.initials: RS
authors.lastname: Nicoloso
authors.forename: Adriana M G
authors.initials: AM
authors.lastname: Ibelli
authors.forename: Marcelo
authors.initials: M
authors.lastname: Bortoli
authors.forename: Aline
authors.initials: A
authors.lastname: Viancelli
authors.forename: Hugo M
authors.initials: HM
authors.lastname: Soares
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D000641:Ammonia / Q000302:isolation & purification*; D001419:Bacteria / Q000235:genetics; D002244:Carbon / Q000032:analysis; D002708:Chlorella / Q000254:growth & development / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D058440:Denitrification; D005798:Genes, Bacterial / Q000235:genetics; D008697:Methane / Q000032:analysis; D058086:Microalgae / Q000254:growth & development / Q000378:metabolism; D009566:Nitrates / Q000032:analysis; D009584:Nitrogen / Q000032:analysis; D009609:Nitrous Oxide / Q000032:analysis*; D010100:Oxygen / Q000378:metabolism; D058433:Photobioreactors / Q000382:microbiology; D062065:Wastewater / Q000737:chemistry*; D018508:Water Purification / Q000295:instrumentation*
chemical_list: D000393:Air Pollutants; D000641:Ammonia; D002244:Carbon; D002734:Chlorophyll; D000077194:Chlorophyll A; D008697:Methane; D009566:Nitrates; D009584:Nitrogen; D009609:Nitrous Oxide; D010100:Oxygen; D062065:Wastewater
keywords: Ammonia; Greenhouse gases; Microalgae; Real-time PCR; Swine wastewater