Regular articleSimulation of phage dynamics in multi-reactor models of complex wastewater treatment systems

- Models of phage and bacterial populations adapted to multi-reactor scenarios.
- Phage dynamics incorporated into models of wastewater treatment.
- Scenarios explored treating wastewater foaming/bulking with phages.
- Phage infection parameters and reactor configuration affect outcome of dosing.

Existing population models of bacteria and phages have most commonly described single well-mixed reactors. Whilst crucial to gain an understanding of population dynamics, these models are not directly applicable to scenarios requiring multi-reactor models. Using standard approaches we have formulated these models to describe behaviour within multiple interconnected reactors. A model incorporating phage dynamics in wastewater treatment systems was then developed to investigate the potential use of phages as a tool to reduce foaming or bulking. The model couples wastewater treatment dynamics within the commercial software GPS-X (Hydromantis Inc.) with phage dynamics through a newly developed add-on called PhageDyn. Simulations predict that immediately after phage dosing there is a lag period during which no apparent changes are observed, which is followed by a sudden and quick increase in the phage concentration and reduction in foaming biomass. “Normalization” without foaming is achieved within 1-2 weeks after dosing. The system may subsequently relapse back to foaming, requiring additional phage dosing, or be “cured” such that the added phages keep the problematic foaming biomass indefinitely at bay. Kinetic parameters describing the behaviour of the phages, as well as reactor configuration, are key determinants of the final outcome. The model is useful for predicting potential behaviour and for determining the characteristics of phages that are likely to be successful, assisting in isolation and screening.