Avaliação do efeito de salinidade sobre a planta Salvinia molesta Mitchell em um experimento piloto de wetland

Abstract

The use of wetlands for sewage treatment brings benefits to health and the environment besides being a process that does not require electrical energy for its operation. On the other hand, the use of aquatic macrophytes in the treatment of industrial effluents, mainly of petroleum origin, at the polishing stage of a season is not a common practice. The objectives of the work are: to construct a wetland for the study of treatability in the polishing stage of a sanitary and industrial sewage treatment plant; through it to study the feasibility of its use aiming in the efficiency to improve some physical-chemical and biological parameters of the process; quantify the biomass generated; and to make feasible the toxicological study with salt in the studied macrophytes, Salvinia molesta, since the petroleum tributary is extremely saline. A saline stress caused by the excessive concentration of KCl in the plant organism was found through the toxicological study. The results found to characterize the parameters listed were: variation between 15 and 30ºC in air temperature and in the beds; 1,833 to 2,930μS / cm of conductivity; 1.4 to 6.7 mg / L OD; 7.1 to 9.2 pH; 63 to 218mg / L of COD; 5 to 304 NTU of turbidity and 52 to 332mg / L Pt.Co of color. In addition, a range of 25 to 440 g / m² of living biomass was produced and a range of 1.7 to 8.6 kg was withdrawn. The Salvinia is resistant to saline effluents up to about 15,000μS / cm. The evidence of salt resistance was found in the results of toxicity tests (number of dead plants / 1000x conductivity): 1/4; 2/6; 0/8; 1/10; 100/10; 0/15; 100/20 and 100 plant killed / 25,000μS / cm conductivity. The results also showed the need to review the wetlands sizing method and the higher COD, conductivity, color and turbidity concentrations in the effluents in relation to the tributaries.