A moving-boundary model of reactive settling in wastewater treatment. Part 2: Numerical scheme

A numerical scheme is proposed for the simulation of reactive settling in sequencing batch reactors (SBRs) wastewater treatment plants. Reactive process sedimentation flocculated particles (biomass; activated sludge) consisting several material components that react with substrates dissolved fluid. An SBR operated cycles consecutive fill, react, settle, draw and idle stages, which means volume tank varies surface moves time. The modelled by a system spatially one-dimensional, nonlinear, strongly degenerate parabolic convection-diffusion-reaction equations. This coupled via conditions mass conservation to transport equations on half line whose origin located at moving boundary models effluent pipe. finite-difference proved satisfy an invariant-region property (in particular, it positivity preserving) if executed simple splitting way. Simulations are presented modified variant established sludge model no.~1 (ASM1).