Direct Potable Reuse for the City of San Diego, California

Abstract

The objective of this project is to design a direct potable reuse facility that is capable of supplementing drinking water sources to the city of San Diego, CA, while minimizing the amount of chemicals added throughout the process. The proposed facility is designed to accommodate 72 million gallons of wastewater per day and treat the influent using numerous pieces of equipment that remove particles based on particle diameter or mass. In addition to using filtration medium to remove particulates, aeration tanks containing activated sludge promote biological digestion while continuously stirred tank reactors irradiated with ultraviolet light and injected with hydrogen peroxide disinfect and oxidize biological and chemical constituents. The economic analysis estimates the proposed facility to cost $557 million dollars and have a lifetime of 25 years. Additionally, the net present value after the 25-year lifetime of the facility at an interest rate of 9% is - $2 billion. Due to the need of increasing the water supply for expanding populations and anticipation of future droughts, the proposed design is recommended for implementation. However, a pilot-plant or demonstration facility should be performed due to the sensitivity of the equipment in the facility to the influent water quality.