NOVELTY - The method involves adapting three-dimensional lattice gas cellular automata model with cube shaped structure. The central node on two faces of the cube is expressed as dispersion nodes of the cell. A state of the cell is expressed by a state of the node and the presence or absence of the reaction particle is determined. The initial state of the model is set such that micro organism state and organic pollutant state is in initial time. The nodes are distributed according to the probability 0-1. The evolution law of model is designed.    USE - Visual simulation method of sewage purifying process.    ADVANTAGE - The simulation model describes the dynamic evolution in the sewage treatment through sewage sludge method so that the micro evolution of active sludge system becomes clearer and easier to the master. The effluent quality BOD is monitored directly by observing the change of reaction and the control decision and dynamic simulation of sewage treatment plant can be conducted easily.    DETAILED DESCRIPTION - The method involves determining the state of the particle. The state of the dispersion node particle is in four states. The state static node particle is in the states of micro organism and gas. A free diffusion function takes place in organic micro organism. The micro organism with metabolic and absorption function is dispersed freely. A model is built using a rectangular solid of nasterisknasteriskm as a container. The cube of nasterisknasteriskn is used as a sewage reaction space and divided into LasteriskLasteriskL of nodes as static node of initial model where L is an integer. The initial state of the model is set. The organic pollutant is distributed on the dispersion nodes because the state has randomness to a certain extent. The initial time of some state is appeared when the probability is a. The initial time of some state does not appear when the probability is 1-a. The nodes are distributed according to the probability 0-1. The evolution law of model with a dispersion process, reaction process and settling process is designed.    DESCRIPTION OF DRAWING(S) - The drawing shows a perspective view of cellular automata model.