A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Environment, Resources and Development

Thesis (M.Eng.) - Asian Institute of Technology, 1984

Combined treatment of septage and wastewater, was investigated in a series of pilot-scale waste stabilization ponds (WSP) , under ambient conditions. The system consisted of three ponds in series, a facultative pond followed by two aerobic ponds. Septage was fed manually to the facultative pond (pond 1) at 0%, 23, 10%, and 20% of wastewater volume. The pond performance in term of physical, chemical. and biological characteristics of the effluent was evaluated. The results of the experiment snowed that a mixing ratio of 10 part of septage with 90 part of wastewater. was optimum, corresponding to a 78.4% reduction in BOD and 99.9% removal of fecal coliforms The septage addition to the pond contributed nutrients to the pond water, resulting faster algal growth as was evidenced by chlorophyll-a concentrations . Septage was found. to exert a significant influence on the BOD-removal kinetics. An attempt was made to describe this effect in the form of a mathematical model. The developed mathematical model was verified using the data of the present study and the data reported by ARIFIN (1982) .The model showed a considerable agreement between the predicted and experimental value of the K with a correlation coefficient of O. 9596. This empirical. relationship can be used to design a single-cell pond receiving septage mixed with wastewater. A design example illustrating the model application is presented.