Pressurized hydrogenotrophic denitrification reactor for small water systems

• Published in: Journal of environmental management 2018-06, Vol.216, p.315-319
• Main Authors: Epsztein, Razi, Beliavski, Michael, Tarre, Sheldon, Green, Michal
• Format: Article
• Language: English
• Subjects: Drinking water; Hydrogen utilization; Hydrogenotrophic denitrification; Nitrate removal; Nitrogen accumulation; Perchlorate removal
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2017.03.010

The implementation of hydrogenotrophic denitrification is limited due to safety concerns, poor H2 utilization and low solubility of H2 gas with the resulting low transfer rate. The current paper presents the main research work conducted on a pressurized hydrogenotrophic reactor for denitrification that was recently developed. The reactor is based on a new concept suggesting that a gas-liquid equilibrium is achieved in the closed headspace of denitrifying reactor, further produced N2 gas is carried out by the effluent and gas purging is not required. The feasibility of the proposed reactor was shown for two effluent concentrations of 10 and 1 mg NO3−-N/L. Hydrogen gas utilization efficiencies of 92.8% and 96.9% were measured for the two effluent concentrations, respectively. Reactor modeling predicted high denitrification rates above 4 g NO3−-N/(Lreactor·d) at reasonable operational conditions. Hydrogen utilization efficiency was improved up to almost 100% by combining the pressurized reactor with a following open-to-atmosphere polishing unit. Also, the potential of the reactor to remove ClO4− was shown. •A pressurized H2-based reactor for denitrification is presented.•The common misconception of N2 accumulation in closed headspace was eliminated.•Reactor modeling predicted high removal rates above 4 g NO3−-N/(Lreactor·d).•Complete H2 utilization was achieved by small open-to-atmosphere polishing unit.•The potential of the reactor to remove ClO4− was shown.