ANÁLISE ECONÔMICA DE UM SISTEMA DE APROVEITAMENTO DE ÁGUA DE CHUVA EM UNIDADE HOSPITALAR
Rainwater. Hospital laundry. Reservoir capacity. Sustainability.
The use of rainwater-harvesting technologies has been highly consolidated as an alternative water supply source in several uses. The advantage in using this technology is based on the water accessibility during the dry season, which makes possible to replace the water from the public supply system. The aim of this study was to financially investigate two rainwater-harvesting systems for the laundry supply in a hospital unit in the cities of Natal and Caicó. For this purpose, a daily scale simulation model of the system hydrologic behavior was developed. The study considered the optimization of the rainwater use as a way to minimize water consumption costs related to the public supply. Taking into account the current technologies in this area, this study used a high-density polyethylene (HDPE) geo-membrane coating semi-underground reservoir as solution, which allows the installation of large capacity low-cost reservoirs, suitable for high water demands and lack of uniformity in precipitation temporal distribution. Simulations involving several rainwater-harvesting scenarios were performed when rainwater supplied laundry services at Onofre Lopes University Hospital (Natal) and Seridó Regional Hospital (Caicó). Financial analysis comprised the Net Current Value, Internal Return Rate and payback. It allowed selecting the most adequate solution for each case. Natal 500 m3 reservoir capacity would produce R$ 81,143.10 annual savings (44% water bill reduction) and a seven-month payback. Caicó unit obtained results demonstrated that a 2,000 m3 reservoir capacity would produce R$ 40,154 annual savings (68% water bill reduction), and a 24-months payback.