An independent water system with maximized wastewater reuse for non-potable purposes - Model case for future urban development

A study was conducted to formulate an optimized plan for upgrading an independent water system in a college campus where the available water source is from 5 groundwater wells with a maximum water supply capacity of 3000 m3/d but the water demand is much beyond this value for both potable and non-potable consumption. By water balance analysis, it was estimated that with the available fresh water consumed only for potable and related miscellaneous uses for 30000 people, the quantity of the reclaimed water could be enough to cover all the non-potable consumption. By material balance analysis, the pollutant loadings of organics, nitrogen and phosphorus were calculated and the requirements for pollutant removal corresponding with reuse purposes were evaluated. Considering the quality criteria of water reuse for lake landscaping, toilet flushing and gardening, and the demand for each water usage in the campus, a dual-quality reclaimed water supply scheme was proposed as (1) supply of lower quality reclaimed water for gardening and road sprinkling by upgrading the existing wastewater treatment facility of 1500 m3/d using conventional process, and (2) supply of higher quality reclaimed water for lake water replenishment and toilet flushing by implementing a new wastewater treatment facility of 2500 m3/d using MBR process. The independent water system thus optimized could sustain a total water consumption of more than 6000 m3/d using the 3000 m3/d source water. This provided a model case for future urban development in the water deficient region.