Non-steady state modeling of extracellular polymeric substances, soluble microbial products, and active and inert biomass

We present a modeling approach that quantifies the unified theory presented in the companion paper. In this approach, we use mathematical modeling to quantify the relationships among three solid species - bacteria, extracellular polymeric substances (EPS), and inert residual biomass - two soluble microbial products (SMP), original substrate, and an electron acceptor. According to the model, donor electrons are used for the synthesis of biomass, EPS, and utilization-associated products. Residual inert biomass and biomass-associated products are produced from the decay of active biomass and the hydrolysis of EPS, respectively. The model includes mass balance equations that consistently describe the flow of electrons among the components. It is solved with a set of parameters appropriate to the experimental study of Hsieh et al. (Biotech. Bioeng. 44 (1994) 219). Model outputs capture all trends observed in steady-state CSTR experiments and transient batch experiments. This agreement supports that the unified theory correctly captures the interconnections among SMP, EPS, and active and inert biomass.