Avaliação de um sistema de dessalinização de água salobra em escala piloto

Abstract

Concerned about the intrusion of sea water, scarcity and poor quality of freshwater reserves in the world, several countries have studied and proposed high technology systems that are feasible for the desalination of brackish or saline water. The main objective of this work was to evaluate the efficiency of an ultrafiltration (UF) system as a pretreatment, followed by slowing and reverse osmosis (RO) for pilot scale saline water desalination, installed in Praia de Leste – coast of the state of Paraná. To obtain the brackish water, the water of the Pombas River was mixed with sea water up to the concentration of 1500 (± 100) mg. L-1 total dissolved solids (TDS). The system was designed to produce 1 m3.h-1 of freshwater (permeate from the RO) and was operated by approximately 3 hours per day during twenty non-consecutive days. Samples from nine collection points were analyzed during the first (A), second (B) and third (C) hours of operation. In order to evaluate the water quality, the parameters evaluated were: TDS, electric conductivity, pH, temperature, apparent color, turbidity, total alkalinity, total hardness, calcium, chloride, sulfate, total coliforms and E.coli. To evaluate the efficiency of the system, the recovery rate and the filtration flow were calculated, as well as the reading of other operational parameters such as osmotic pressure. It was found absence of total coliforms and E. coli in the permeate. There was variation regarding to the removal of total hardness and calcium by the softener due to the regeneration time of the system. The RO system obtained an average of 99.4% of the TDS removal and the highest overall (UF and RO) recovery rate was 57.4%.