On-site performance of floating treatment wetland macrocosms augmented with dye-degrading bacteria for the remediation of textile industry wastewater

Floating treatment wetlands (FTWs) are considered as cost-effective remediation options for various types of wastewater. Their effectiveness has been shown in several lab-scale and pilot-scale studies; however, there is a paucity of published data on pilot-scale systems treating genuine wastewater. This study aims to assess the performance of a pilot-scale system, carrying Phragmites australis in combination with three plant growth promoting and dye-degrading bacteria (Acinetobacter junii strain NT-15, Rhodococcus sp. strain NT-39, and Pseudomonas indoloxydans strain NT-38) for the treatment of textile industry wastewater (Interloop Limited, Faisalabad, Pakistan). Fifteen FTW macrocosms were established comprising plants and bacteria separately or in combination. Each unit was capable to carry 1000 L of the wastewater and the system was operated in a batch-wise mode for the period of 2 years. After a year of installation, performance of all FTWs units was optimal. A high removal in organic and inorganic pollutants was observed in the vegetated tanks, whereas combined application of plants and bacteria further enhanced the removal performance, i.e., chemical oxygen demand was reduced to 92%, biochemical oxygen demand to 91%, color to 86%, and trace metals to approximately 87% in the wastewater. The augmented bacteria displayed persistence in water as well as in the roots and shoots of P. australis suggesting a potential partnership with the host towards enhanced performance. Treated wastewater met the National Environmental Quality Standards (NEQS) set by the Government of Pakistan, thus, suggesting its discharge in the surface water without any potential risks. This pilot-scale study is a step forward towards sustainable remediation of the textile wastewater in the field. (C) 2019 Elsevier Ltd. All rights reserved.