Producing free nitrous acid - A green and renewable biocidal agent - From anaerobic digester liquor
Author(s)
Law, Yingyu
Ye, Liu
Wang, Qilin
Hu, Shihu
Pijuan, Maite
Yuan, Zhiguo
Griffith University Author(s)
Year published
2015
Metadata
Show full item recordAbstract
Recent studies have shown that free nitrous acid (FNA) at parts per million is strongly biocidal to a broad range of microorganisms involved in wastewater management. Applications have been developed, where FNA is used to deactivate anaerobic sewer biofilms thus suppressing sulfide and methane production in sewers, or to lyse secondary sludge resulting in reduced sludge production and enhanced biogas production. This study examines the feasibility of producing FNA from a waste stream namely the anaerobic sludge digestion liquor, thus providing a source of FNA for the above applications within wastewater systems. Complete ...
View more >Recent studies have shown that free nitrous acid (FNA) at parts per million is strongly biocidal to a broad range of microorganisms involved in wastewater management. Applications have been developed, where FNA is used to deactivate anaerobic sewer biofilms thus suppressing sulfide and methane production in sewers, or to lyse secondary sludge resulting in reduced sludge production and enhanced biogas production. This study examines the feasibility of producing FNA from a waste stream namely the anaerobic sludge digestion liquor, thus providing a source of FNA for the above applications within wastewater systems. Complete nitritation was achieved in a lab scale sequencing batch reactor (SBR) treating reject wastewater. Under stable operation, the system sustained more than 90% conversion of the 1.0 and 0.8 g NH4+-N/L contained in the synthetic and real digester liquor, respectively, to nitrite. Each liter of this nitrite rich effluent could be acidified to pH 2 with only 66 mmol of H+, due to the low level of alkalinity in the effluent. This converts almost all of the nitrite to FNA providing an ample source of FNA for sewer and sludge pretreatment applications. Despite the high nitrite concentration in the reactor, minimal N2O was produced with an emission factor of 0.08% of the ammonium nitrogen converted. Finally, an economical assessment of a theoretical full-scale installation for FNA production was conducted and compared with the costs of producing this FNA from a commercial nitrite supply.
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View more >Recent studies have shown that free nitrous acid (FNA) at parts per million is strongly biocidal to a broad range of microorganisms involved in wastewater management. Applications have been developed, where FNA is used to deactivate anaerobic sewer biofilms thus suppressing sulfide and methane production in sewers, or to lyse secondary sludge resulting in reduced sludge production and enhanced biogas production. This study examines the feasibility of producing FNA from a waste stream namely the anaerobic sludge digestion liquor, thus providing a source of FNA for the above applications within wastewater systems. Complete nitritation was achieved in a lab scale sequencing batch reactor (SBR) treating reject wastewater. Under stable operation, the system sustained more than 90% conversion of the 1.0 and 0.8 g NH4+-N/L contained in the synthetic and real digester liquor, respectively, to nitrite. Each liter of this nitrite rich effluent could be acidified to pH 2 with only 66 mmol of H+, due to the low level of alkalinity in the effluent. This converts almost all of the nitrite to FNA providing an ample source of FNA for sewer and sludge pretreatment applications. Despite the high nitrite concentration in the reactor, minimal N2O was produced with an emission factor of 0.08% of the ammonium nitrogen converted. Finally, an economical assessment of a theoretical full-scale installation for FNA production was conducted and compared with the costs of producing this FNA from a commercial nitrite supply.
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Journal Title
Chemical Engineering Journal
Volume
259
Subject
Chemical engineering
Civil engineering
Environmental engineering
Environmental engineering not elsewhere classified