A new semi-analytical solution for the contaminant reactive-transport equation in the subsurface

Modeling biodegradation in the subsurface has been studied intensively in the last two decades. The governing equations that describe this process are coupled nonlinear partial differential equations (PDEs) that involve physical (transport), chemical (sorption), and biological (biodegradation) processes. The connection between all PDEs equations through the non-linear ordinary differential reaction equations makes it difficult to obtain analytical solution for the problem. Therefore, time splitting algorithm (TSA) is usually used to solve such kind of equations; in which the convective-dispersive part is solved separately using a powerful numerical technique and then combined, on the time step level, with a numerical solution of the reaction terms. A new iterative semi-analytical solution for the transport PDEs is presented here. The method is tested in a 1 -D problem. Results obtained using this new iterative method are compared to results obtained using the numerical model "METABIOTRANS" for the same problem. The results obtained suggest extending the method to 2 and 3-D problems.