Technical and Financial Feasibility Study on Recycle Water Treatment System from Wastewater: A Case Study of Automobile Manufacturer

Abstract

The objective of this research is to study the possibility to take the wastewater from production and processes in the factory which are already treated by the wastewater treatment system to recycle in order to replace the tap water. The technical study of the recycle water treatment system from wastewater compares the properties of four membrane types including microfiltration, ultrafiltration, nanofiltration and reverse osmosis membranes to choose ones that are appropriate with the characteristics of the wastewater from the factory. The technical feasible alternative is then analyzed the financial aspects for decision making. According to the technical study result, it shows that the recycle water treatment system from wastewater should consist of two main membrane units, the pre-treatment unit with a microfiltration membrane and the purified unit with a reverse osmosis membrane regeneration. For the financial analysis at 10% discount rate, it shows that the net present value is 1,077,668.46 baht, the internal rate of return is 11.11% which is higher than the minimum attractive rate of return, the benefit/cost ratio is 1.03 and the discount payback period is 13 years and 2 months, indicating that the project is feasible to invest. The sensitivity analysis varies four factors within the range of ±25% including the capital investment cost, the benefit, the operating expenses and the discount rate. The changes in the factors that result in the infeasibility of the project are 10% increase in the capital investment cost, 10% increase in the operating expenses, 5% decrease in the benefit and 15% increase in the discount rate.