Production of Nitrous Oxide From Anaerobic Digester Centrate and Its Use as a Co-oxidant of Biogas to Enhance Energy Recovery

• Published in: Environmental science & technology Vol. 48; no. 10; pp. 5612 - 5619
• Main Authors: Scherson, Yaniv D, Woo, Sung-Geun, Criddle, Craig S
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 20.05.2014
• Subjects: Ammonium Compounds - metabolism; Anaerobiosis; Applied sciences; Bacteria - genetics; Batch Cell Culture Techniques; Biofuels - analysis; Biogas; Biological and medical sciences; Biological treatment of waters; Bioreactors - microbiology; Biotechnology; Chemical compounds; Climatology. Bioclimatology. Climate change; Comamonas; Conservation of Energy Resources; Conversion; Earth, ocean, space; Environment and pollution; Exact sciences and technology; External geophysics; Fundamental and applied biological sciences. Psychology; General purification processes; Industrial applications and implications. Economical aspects; Meteorology; Nitrites - metabolism; Nitrogen; Nitrous Oxide - metabolism; Oxidants - chemistry; Oxidation; Oxidation-Reduction; Phosphorus; Pollution; Refuse as fuel; RNA, Ribosomal, 16S - genetics; Waste Water - microbiology; Wastewaters; Water Purification; Water treatment and pollution; Water treatment; Alternative energy; Energy recovery; Biogas; Oxidant; Sustainable development; Anaerobic digestion; Biological purification; Bioreactor; Renewable energy; Sequencing batch reactor; Greenhouse gas; Bioenergy; Waste water purification; Resource management; Nitrogen protoxide; Microbial community
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es501009j

Coupled Aerobic-anoxic Nitrous Decomposition Operation (CANDO) is a new process for wastewater treatment that removes nitrogen from wastewater and recovers energy from the nitrogen in three steps: (1) NH4 + oxidation to NO2 –; (2) NO2 – reduction to N2O gas; and (3) N2O conversion to N2 with energy production. In this work, we optimize Steps 1 and 2 for anaerobic digester centrate, and we evaluate Step 3 for a full-scale biogas-fed internal combustion engine. Using a continuous stirred reactor coupled to a bench-scale sequencing batch reactor, we observed sustained partial oxidation of NH4 + to NO2 – and sustained (3 months) partial reduction of NO2 – to N2O (75–80% conversion, mass basis), with >95% nitrogen removal (Step 2). Alternating pulses of acetate and NO2 – selected for Comamonas (38%), Ciceribacter (16%), and Clostridium (11%). Some species stored polyhydroxybutyrate (PHB) and coupled oxidation of PHB to reduction of NO2 – to N2O. Some species also stored phosphorus as polyphosphate granules. Injections of N2O into a biogas-fed engine at flow rates simulating a full-scale system increased power output by 5.7–7.3%. The results underscore the need for more detailed assessment of bioreactor community ecology and justify pilot- and full-scale testing.