Biology of Fixed-Growth Process

Although the fundamental principles of biological processes are the same for all process configurations, the constraints of fixed-growth processes result in particular characteristics of microbial communities and advantages and disadvantages relative to alternative systems. In

fixed-growth processes, fluid containing necessary nutrients passes over the microorganisms

growing in a biofilm on a support surface. Nutrients diffuse into the biofilm and are metabolized by the immobilized microorganisms.

                                Oxidation  氧化                                                      Denitrification  反硝化

                                CHON+O₂→CO₂+H₂O+NH₄⁺                                  2NO₃^-+10e+12H⁺ →N₂+6 H₂O

                                Nitrification  硝化                                                   Anammox  厌氧氨氧化

                                NH₄⁺+1.5O₂ →NO₂^-+2H⁺+H₂O                               NH₄⁺+ 1.32NO₂^- + 0.066HCO₃^- +0.13H⁺→

                                NO₂^-+0.5O₂ → NO₃^-                                                                1.02N₂+0.26NO₃^-+0.066CH₂O_0.5N_0.15+2.03H₂O