A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering

Thesis (M.Eng.) - Asian Institute of Technology, 1992

Chao Phraya River and Bangkok Basin are the study areas of this research. Presently, Chao Phraya River does not meet the water quality standard, especially in the Bangkok region. The water quality analysis method was investigated in this research in order to make a plan of the basin-wide sewerage system to meet the water quality standard. In the water quality analysis, a steady state one-dimensional model was applied to the Basin-wide Sewerage Planning. DO and BOD were used as the analytical different method was applied parameters in the model. The finite to the model by dividing the river into a finite number of segments . The coefficient considered in this research were: dispersion coefficient referring to the Elder's equation, reaeration rate referring to the O'Connor and Dobbins's equation and deoxygenation rate deriving from the calibrated result of measured DO and BOD concentration in the river. Chao Phraya River in Bangkok region is divided into 33 segments in this model. The results from the model were applied to planning of the sewerage system on the assumption that the study area was divided into 7 zones. By considering the river flow rate of 100 cu.m./sec, t h e pre dicted quality of the river in year 2000 will not meet the water quality standard of ·chao Phraya River. As a result, the minimum percent removal of organic pollutants by the sewerage system which should be served in this area are 84%, in order to comply with the water quality water standard .