Fig. 4 Microbial biomass and As(V) concentrations versus time for a representative As treatment (60 µM) inoculated with CN-8. The fitted microbial growth curve was generated assuming first order kinetics (dX/dt = kX) until a maximum of X = 2.7 mM C was reached. The solved expression for X was substituted into the As(V) reduction model (see Eq. [1]) and the As(V) reduction curve generated by optimizing k₁