In this paper, the numerical simulation for the in situ degradation of toxic water pollutants in the presence of semiconductor catalyst particles is considered. The computer simulation is in search of an efficient photocatalytic reactor design to achieve better fluid-catalyst contacting to minimize mass transfer limitation. In addition, in the present work, a state-of-the-art efficient computational technique, namely, distributed computing, has been employed to expedite the speed of calculation and overcome the memory bottleneck present in a single workstation. A comparative study has also been made of the computational effort required for a serial, parallel and distributed computing environment. The results show that the distributed computing technique is an economical and efficient method for overcoming difficulties, such as the memory bottleneck present in single workstations and thr long computation time, associated with computer simulations of reacting flows.