As a result of increased environmental awareness and interest in the effective protection of the environment from pollution, the restrictions have increased on the disposal of wastewater, and the need to the treatment plants has arisen to treat the wastewater prior to disposal in water bodies, whether water from either large or small communities. As a result of the importance of these facilities and cost of material massive construction, operation and maintenance. In order to facilitate the design process and calculate the initial cost it was issued some software that helps engineer in the design of the various parts of the station, and in order to choose the equipments and comparison between several alternatives in objective ways to choose the most appropriate. Some of these programs are dynamics. It has the ability to simulate the work of the treatment plant along the time and predict its efficiency and performance. STOAT is a software that aims to model and simulate wastewater and industrial wastewater treatment plant, and it is one of the newest technology that uses the latest developments in process modelling, simulation and a wide range of tools that simplifies the model building and simulation and give the results in graphics and tables, allowing us to examine the complex interactions between the various units within the station by interactive and dynamic methods and this is important for the effective design, operation and management of wastewater treatment plants. Hence, we take the coastal area as a case study where there are number of modern wastewater treatment plants of small agglomeration and is being work, as Kherbet al-Maaze wastewater treatment plant in Tartous. Using STOAT, the study shows a good efficiency and performance of Kherbet al-Maaze WWTP using (ASM1,ASAL1) models, and we could build several scenarios like arrival of high pollution load to the station in order to evaluate and predict its performance.