Benefit of the Drinking Water Supply System in Office Building by Rainwater Harvesting: A Demo Project in Hanoi, Vietnam

Abstract

Vietnam is a developing country with the rate around 5%–6% per year, especially in urban areas. Rapidly developed urban areas lead to stress for infrastructure and the water supply is also stressed. In Hanoi city, total water capacity from the manufactories is around one million cubic meters per day and almost the entire main water source is groundwater but it is not enough to supply all of Hanoi’s people, especially in the summer. A demo project is implemented in Hanoi University of Civil Engineering (HUCE) to produce drinking water by using the rainwater and membrane system and supply for people. In this project, rainwater is collected on the rooftop of the lecture building with an area of around 500 m 2 and 100 m 3 volumetric rainwater tanks. Afterwards, the rainwater is treated by the micromembrane system and supplied to the tap water. Total cost for construction, technology and operation in the first year is around USD 48,558. In the long-term (15 yr) if HUCE invests in the same system, with 20 m 3 volumetric storage tank, it can provide drinking water for 500 staffs in every year. The cost of investment and operation for this system is lower than 30% compared to buying bottled water with the price USD 1.8/bottle. The drinking water parameters after treatment are pH, 7.3–7.75; turbidity, 0.6–0.8 NUT; total dissolved solids, 60–89 mg/L; coliform, 0; heavy metal similar with water quality in the bottle water in Vietnam.