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

Thesis (M.Sc.) - Asian Institute of Technology, 1997

This study investigates the feasibility for the operation of domestic wastewater treatment by chemical precipitation. In this study AIT wastewater was employed as a domestic wastewater being treated. Three coagulants which are ferric chloride, polyaluminium chloride and ferric sulfate were employed as a coagulants. Jar test which was used to determine the optimum coagulant dosage and pH results that the most appropriate coagulant, among above three coagulants, for applying with AIT wastewater treatment is fenic chloride. The optimum dosage and pH of ferric chloride are 400 mg/l and 8.0 respectively. By applying ferric chloride as a coagulant for AIT wastewater treatment through a chemical precipitation, it is found that the effluent concentration are met requirement of the DEG. The effluent concentration and the removal efficiency for removal of BOD, TSS, TDS, Org-N and TP, which are 16 mg/l, 4 mg/l, 15 mg/l, 4 mg/l, and 0.4 mg/l respectively, and 70%, 89%, 32%, 33% and 80% respectively, can be achieved through chemical treatment system. From comparison between chemical treatment process and biological treatment process, it is interesting to indicate that the chemical treatment process has more advantages over the biological treatment process. As above it can be indicated that chemical wastewater treatment is an acceptable method for domestic wastewater treatment, and can replace the conventional biological treatment system.