Análise da influência da macrófita Typha domingensis e da linhagem bacteriana Shewanella sp. G5-03 na biorremediação de efluente têxtil sintético contendo o corante azo vermelho congo (C.I direct red 28)

Abstract

Synthetic dyes represent for one of the major groups of recalcitrant compounds, which are widely used by the textile industry. They are responsible for water pollution and to produce a high chemical oxygen demand (COD), biochemical oxygen demand (BOD), harsh pH levels, salts, metals and coloring, at the discharge place of effluent. Its treatment demands the usage of a complex and costly technologies to minimize the caused impacts, besides being often inefficient. The bioremediation/phytoremediation techniques have proven its efficiency in the treatment several types of pollutants, like heavy metals, polycyclic aromatic hydrocarbons, pesticides, textile dyes, among others. Thus, the aim of this study was to evaluate the use of an efficient and cost-effective technique through the evaluation of macrophyte Typha domingensis and Shewanella sp. G5-03 bacterial strain influence on synthetic textile effluent deterioration using Congo red dye. Thus, laboratorial experiments were made using a previously chosen strain under specific temperature conditions, pH and incubation conditions. Then, a hybrid system consisting of a bioaugmented bioreactor was built including Shewanella sp. G5-03 strain. And this system was connected to two wetlands systems assembled in serie with the macrophyte Typha domingensis present. A synthetic effluent was developed under laboratory conditions using 50 mg/L of Congo red dye (Direct Red 28). A continuous flow of 9.5 ml/min was set with hydraulic holding time of 7 hours at the bioreactor and 43,8 hours for the wetland. Two collection points were set at the bioreactor and wetland exits, which parameters were analyzed: COD, redox potential, turbidity, ammonia, orthophosphate, aromatic amines, dye concentration and phytotoxicity. The results showed viability of the chosen species for the effluent treatment, mainly at the removal of color and organic matter, despite the low nutrient removal due to the anaerobic environment obtained into the system.