화학공학소재연구정보센터
Journal of Bioscience and Bioengineering, Vol.126, No.2, 213-219, 2018
Immobilization of Azospira sp strain I13 by gel entrapment for mitigation of N2O from biological wastewater treatment plants: Biokinetic characterization and modeling
Development of a strategy to mitigate nitrous oxide (N2O) emitted from biological sources is important in the nexus of wastewater treatment and greenhouse gas emission. To this end, immobilization of N2O-reducing bacteria as a biofilm has the potential to ameliorate oxygen (O-2) inhibition of the metabolic activity of the bacteria. We demonstrated the effectiveness of calcium alginate gel entrapment of the nosZ Glade II type N2O-reducing bacterium, Azospira sp. strain I13, in reducing levels of N2O, irrespective of the presence of O-2 . Azospira sp. strain I13 cells in the gel exhibited N2O reduction up to a maximum dissolved oxygen concentration of 100 mu M in the bulk liquid. The maximum apparent N2O uptake rate,& nbsp; V'(m,N2O), by gel immobilization did not appreciably decrease, retaining 72% of the N2O reduction rate of the cell suspension of Azospira sp. strain I13. Whereas gel immobilization increased the apparent half-saturation constant for N2O, K'(m,N2O ), and the apparent O-2 inhibition constant, K'(1,O2) , representing the degree of O-2 resistance, correspondingly increased. A mechanistic model introducing diffusion and the reactions of N2O consumption was used to describe the experimental observations. Incorporating Thieles modulus into the model determined an appropriate gel size to achieve N2O reduction even under aerobic conditions. (C) 2018, The Society for Biotechnology, Japan. All rights reserved.