Simulation as a tool for assessing digestion and liquid stream interactions in the context of new regulations: PRESENTATION ONLY
Conidi, D.1, Dold, P.1, Smith, S.2, 1EnviroSim Associates, Canada, 2Wilfrid Laurier University, Canada
(free)
Regulation of biosolids processing is changing to allow third parties to undertake solids processing, and for biosolids processing including digestion to be operated as standalone business units within an existing STW. The need to fully understand the interactions between digestion / solids processing and liquid stream treatment / effluent quality will be more important under this structure, especially when centrate is returned to the liquid stream for treatment.
Process simulators such as BioWin are widely used for designing and optimising sewage treatment works (STW). When anaerobic digestion is included as part of the process, BioWin can assist in understanding the interactions between solid and liquid streams. These interactions typically are focused on the effect that the digestion and/or dewatering processes have on the liquid stream and the ability to meet quality targets (e.g. return stream ammonia and phosphorus load).
New developments in BioWin that allow consideration of interactions between solids and liquid treatment will be presented including:
- A full sulphur model allowing the prediction of hydrogen sulphide levels in digester off gas,
- Modelling of oxidation/reduction of iron,
- Precipitation of struvite, vivianite, brushite, apatite and iron(II) sulphide, and
- Model validation using PHREEQC.
The ability to simulate the whole STW is a strong tool to help in decision making from both the liquid stream and solids treatment perspectives.
Key Themes: Process modelling & software developments
