Comparison of first-order kinetic models for sewage treatment in horizontal subsurface-flow constructed wetlands.

There are several techniques for sizing horizontal subsurface-flow constructed wetlands systems (CWs), and mathematical models have been frequently used for this purpose because they more accurately represent the liquid behaviour in these reactors. The P-k-C* model has already been used in the prediction of organic matter removal in CWs, but it has been little explored in the literature. On other hand, the model proposed by Chan and Chu [Modeling the reaction kinetics of Fenton's process on the removal of atrazine. Chemosphere. 2003;51(4):305-311] was not known for prediction of organic matter removal in CW systems. In the present work, the kinetic data for chemical oxygen demand (COD) removal of 28 horizontal subsurface-flow constructed wetlands were used to compare the performance of two pseudo-first-order kinetic models (P-k-C* model and model from Chan and Chu. The comparisons of nonlinear regressions were performed considering Akaike information criterion (AIC), root-mean-square error (RMSE), and adjusted coefficient of determination (Radj2). In general, both models were able to provide good predictions of relative remaining concentration (C/C0). However, the Chan and Chu model produced higher adjustment coefficients, showing the potential to be used in modelling and simulation of the degradation kinetics of organic matter in wetlands.