Parâmetros de tratabilidade em sistemas de alagados construídos aplicado ao reuso de resíduos de dessalinização

Abstract

The aim of this research was to evaluate the treatability parameters, which were defined as variables, factors, hydraulic and operating configurations, which, by hypothesis, could potentially influence the process of improving the quality of wastewater (brine) resulting from desalination by ultrafiltration and reverse osmosis, through the application of Constructed Flooded Systems, cultivated with elephantgrass (Pennisetum purpureum, Schum.). The studies were conducted on bench scale, within a semi-heated agricultural greenhouse. Twelve experimental units were established, and four treatment configurations were established with three replicates each, operated and monitored for five months, varying according to the operation of the system, whether continuous or static, and also in the hydraulic holding time of three or four days. Samples of water were collected at the entrance and exit of each unit, and were analyzed in the laboratory for the physico-chemical characterization and monitoring of parameters: pH, alkalinity, dissolved oxygen, turbidity, salinity, hardness, calcium, chlorides, sulfates, conductivity total dissolved solids and chemical oxygen demand. The results were submitted to analysis of variance and Tukey's test, at a 95% confidence level, using the statistical program SISVAR. The systems that were submitted to the static regime, with hydraulic detention time of four days, during the first three weeks of operation, showed to be more efficient in the average removal of salinity (53.1%), hardness (69.2%), calcium (66.7%), chloride (44.5%), electrical conductivity (40.7%) and total dissolved solids (86.7%). The plant was able to absorb 0.25% of the sodium ion by its roots for its nutrition, according to results of the electron microscopy.