Modeling the competition between PHA-producing and non-PHA-producing bacteria in feast-famine SBR and staged CSTR systems

Authored by Leonie Marang, Loosdrecht Mark C M van, Robbert Kleerebezem

Date Published: 2015

DOI: 10.1002/bit.25674

Sponsors: Dutch TechnologyFoundation

Platforms: MATLAB

Model Documentation: Other Narrative Mathematical description

Model Code URLs: http://onlinelibrary.wiley.com.ezproxy1.lib.asu.edu/store/10.1002/bit.25674/asset/supinfo/bit25674-sup-0001-SuppData-S1.docx?v=1&s=3644b4fc1340f7b8083fb6a6d8e5539e20a2689e

Abstract

Although the enrichment of specialized microbial cultures for the production of polyhydroxyalkanoates (PHA) is generally performed in sequencing batch reactors (SBRs), the required feast-famine conditions can also be established using two or more continuous stirred-tank reactors (CSTRs) in series with partial biomass recirculation. The use of CSTRs offers several advantages, but will result in distributed residence times and a less strict separation between feast and famine conditions. The aim of this study was to investigate the impact of the reactor configuration, and various process and biomass-specific parameters, on the enrichment of PHA-producing bacteria. A set of mathematical models was developed to predict the growth of Plasticicumulans acidivoransas a model PHA producerin competition with a non-storing heterotroph. A macroscopic model considering lumped biomass and an agent-based model considering individual cells were created to study the effect of residence time distribution and the resulting distributed bacterial states. The simulations showed that in the 2-stage CSTR system the selective pressure for PHA-producing bacteria is significantly lower than in the SBR, and strongly affected by the chosen feast-famine ratio. This is the result of substrate competition based on both the maximum specific substrate uptake rate and substrate affinity. Although the macroscopic model overestimates the selective pressure in the 2-stage CSTR system, it provides a quick and fairly good impression of the reactor performance and the impact of process and biomass-specific parameters. Biotechnol. Bioeng. 2015;112: 2475-2484. (c) 2015 Wiley Periodicals, Inc.

Tags

selection Mixed microbial cultures Waste-water treatment Activated-sludge Polyhydroxybutyrate production Sugar molasses Polyhydroxyalkanoates Enrichment Acinetobacter Substrate