COST MINIMIZATION OF RAW WATER SOURCE BY INTEGRATED WATER SUPPLY SYSTEMS (A CASE STUDY FOR BANDUNG, INDONESIA)

Due to the population growth, the scarcity of raw water presents a challenging problem for the establishment of an effective urban water supply system. In this research, we address the scarcity of water source for a highly populated city, like Bandung, and then minimize the cost associated with the development of effective urban water supply systems. We apply the concept of Integrated Water Supply System (IWSS), a concept that utilizes the treated wastewater as an alternative source of water. This concept will be implemented for the city of Bandung, Indonesia as a case of study. The cost minimization of the raw water supply system is carried out by using the superstructure approach. This optimization of the IWSS includes raw water sources and recycled wastewater. For the proposed scenario, we build a mathematical model that will be used for the optimization of IWSS. This optimization problem is solved using the CONNOPT3 method of GAMS software. The results of this study show that the proposed new IWSS results in less cost, but higher transmitted water, than the existing system (non-IWSS) because, in the new system, the water supply is allowed to flow into the existing Water Treatment Plan (WTP). Factors affecting the cost are length and diameter of the raw water transmission pipeline, the elevation of water resources and water treatment plants, the use of a coagulant, and the use of electricity in the transmission system and the water treatment plant.