Textile wastewater phytoremediation using Spirodela polyrhiza (L.) Schleid. assisted by novel bacterial consortium in a two-step remediation system

Abstract

The study aims at developing a phyto-microremediation system for textile wastewater treatment using Spirodela polyrhiza (L.) Schleid. and a consortium of bacterial strains isolated from textile wastewater-contaminated matrices and rhizosphere of S. polyrhiza. The sequential phyto-microremediation of textile wastewater was carried out utilizing two-stage phyto-microremediation systems I [phytoremediation system (Stage 1) preceded microremediation system (Stage 2)] and II [microremediation system (Stage 1) preceded phytoremediation system (Stage 2)]. Pseudomonas stutzeri, Janibacter anophelis, Bacillus safensis, Bacillus pumilus, Bacillus thuringiensis, and Bacillus cereus constituted the bacterial consortium that was involved in the microremediation of textile wastewater. Biochemical characterization of Spirodela on exposure to untreated textile wastewater showed cadmium and nickel uptake as 26.03 and 22.99 mg g−1 dw−1. S. polyrhiza exhibited anatomical changes like distortion in the structure of the xylem, phloem, lower epidermis, and increased aerenchyma formation when remediating textile wastewater. The textile wastewater bioremediation in phyto-microremediation system I gives final reduction of COD 77.36%, color 91.70%, calcium 61.65%, iron 69.41%, nickel 89.30%, cadmium 88.37%, nitrate 70.83%, phosphate 73.11%, and sulfate 75.49%. Further, LC-MS analysis of treated wastewater from phyto-microremediation system I have shown biotransformation of metabolites into simpler compounds like 2-{Bis [4-(2-cyanophenoxy)phenyl]methyl}benzoic acid (C34H22N2O4). The FTIR spectrum of bacterial biomass exposed to textile wastewater exhibits substantial shifts of various bands in the IR region for functional groups such as alcohol, alkene, esters, azide, and amine as compared to non-exposed biomass.