In this paper, we drive the concentration of microbial growth in the groundwater system. This model is based on the system of non-linear differential equations. The system of equations is solved by using the new homotopy perturbation method. We followed toluene degradation and bacterial growth by measuring toluene and oxygen concentrations and by direct cell counts. And the total amount of toluene degraded by Pseudomonal putida F1 in the sediment columns increased with rising concentration of the source and flow rate. In contrast, the efficiency of toluene removal slowly decreases. The approximate analytical expression of this model, the concentration of toluene and bacteria also consideration of a metabolite concentration, the microbial growth of attached and suspended bacteria, depending on the simultaneous presence of toluene. Finally, oxygen and dual Monod kinetics are discussed. The analytical solutions are also compared with simulation results and satisfactory the agreement is noted.