A zero-dimensional biofilm model for dynamic simulation of moving bed bioreactor systems: Model concepts, Peterson matrix, and application to a pilot-scale plant

A zero-dimensional (0D) biofilm model for dynamic simulation of biological wastewater treatment systems is proposed and applied to a pilot-scale moving bed bioreactor (MBBR). The model, written in Peterson matrix format, does not describe biofilm structure in any form. Biochemical conversions in the model are based on the activated sludge model no. 1 (ASM1). Diffusional mass transport limitations are taken into account implicitly in the model using adapted half-saturation coefficients in the Monod terms of the model. In addition to biochemical conversions, the model contains attachment of particulates from the bulk of the liquid onto the biofilm and detachment of particulates from the biofilm into the bulk of the liquid. Model performance is evaluated using data originating from two intensive measurement campaigns covering 9 days of wastewater treatment with the pilot-scale MBBR. The process dynamics of the MBBR were well reproduced by the model, since a good fit between measured effluent ammonia and nitrate concentrations to the simulation results was obtained. Biofilm related parameters, like biofilm age, attachment rate and detachment rate, were extracted from the model.