BALANÇO DE MASSA DE UM SISTEMA DE ULTRAFILTRAÇÃO E OSMOSE REVERSA PARA DESSALINIZAÇÃO DE ÁGUA SALOBRA

Abstract

With the unequal distribution of fresh water in the world, strong population growth, climate change and the consequences of anthropological actions it is necessary to look for alternative sources to supply the water demand for human beings, animals and plants. Salt water or brackish water has been the only source of water available for survival in some communities on the planet. This issue has driven the use of desalination techniques. With the objective of studying alternatives for climate adaptation, anticipating of trends and problems and water problems, a brackish water desalination system in pilot scale was implemented on the premises of the Water Treatment Plant Station, in Praia de Leste, in the Pontal do Paraná City, coast of the State. The pilot system was provided with ultrafiltration (UF) as a pretreatment followed by softening and reverse osmosis (RO), with the capacity to produce 1m3.h-1 of permeate. Brackish water was produced at concentrations of 1,000 ± 50 mg.L-1 and 1,500 ± 20 mg.L-1 of total dissolved solids (TDS), by mixing sea water and fresh water from the Pombas River, which supplies the town. The global system was evaluated from production and water consumption data, mass balance and recovery rates for different configurations of the reverse osmosis system. For this, four experiments were performed, varying the configuration of the valve which controls the flow of the brine: the first one with 72.71% (A); the second with 59.20%(B); the third with 39.70% (C), these with 1,500 ± 20 mg.L-1 of TDS; the fourth experiment was also performed for 1,000 ± 50 mg.L-1 of TDS with 32.90% of the brine (D). About 15% of volume of water produced was used in the hydraulic cleaning of the UF and RO membranes. When the flow rates of the concentrate were higher, the feed rates were also higher and consequently, the recovery rates and osmotic pressure were lower. The highest recovery rate was 69.13% for the experiment D, being considered the most optimized configuration.