Water Treatment Plant (or WTP) is the most important part of the Power Plant, because it produces vital-water it needs for steam production. Power Plants are the biggest air, ground and groundwater pollutants. Bad water quality directly impacts machine duration. Polluted water from Water Treatment Plant has a negative effect on people, flora and fauna, thus better waste management programs should be put in place to eliminate this problem. In this paper we are going to present the de-carbonization process of raw water as a part of water treatment plant, within coal fired power plants. De-carbonizing water is a time consuming process. We are going to present an advanced method for process identification with big time delay. The results are compared and one of the most appropriate methods is selected as identification method for this process. Further research and possibilities in this area are going to be presented by the end of the paper.Progress in identifying the process by which we work in this paper may serve as a new way to identify highly nonlinear processes. The used algorithm for identification of the process that is outlined in this paper can be applied, and it will be the basis for the creation of the software for the application of microcomputer techniques. Here we are applying the relevant software which can be applied in the form of programming packages for identification. This has to do with passive identification methods.