Evaluating the Impact of Imperfect Mixing on the Performance of Stormwater Treatment Ponds

Paper in proceeding, 2004

The impact of imperfect mixing on the performance of two full-scale stormwater treatment ponds was evaluated using compartmental modelling. The hydrodynamic component of the model consists of a series of appropriately interconnected well mixed tanks and is proposed as the simplest model capable of accurately describing the behaviour of a system with hydrodynamic characteristics such as short-circuiting, recycling and stagnation. A kinetic model incorporating first order removal of total suspended solids (TSS) was linked to the simple hydrodynamic model to evaluate performance. Model validation was carried out using experimental tracer response data and two dimensional simulated flow patterns. Results obtained reveal a significant reduction in TSS removal as a result of imperfect mixing. This study highlights the usefulness of relatively simple compartmental models as a tool for evaluating the impact of imperfect mixing on the performance of stormwater treatment ponds.