Enhanced removal of dissolved aniline from water under combined system of nano zero-valent iron and Pseudomonas putida

Abstract

Aniline is a toxic chemical released by many industries. Removal of pollutants by micro-organisms is the most recent area of research whereas nano zero valent iron (nZVI) in recent time has been widely used in treatment of groundwater. The present study aims to understand the nature of interaction of nZVI with bacteria and removal of aniline under a combined system of bacteria and nZVI. nZVI were synthesized through conventional process and its adsorption studies on aniline removal were performed. Pseudomonas putida MTCC 1194 strain was acclimatized to aniline in Basal salt medium for a period of 2 months. The maximum growth rate and yield coefficient of cells were determined and within 6 h 99 % removal of 200 ppm aniline was found to be achieved. Adsorption studies were performed using nZVI of different concentration on 200 ppm aniline for 6 h. Maximum aniline removal was obtained at 85 % in distilled water and 92 % in basal salt medium, respectively using 5 g/L nZVI. nZVI was found to be growth inducer to the mentioned strain. A combined system of aniline removal was studied consisting of biodegradation and adsorption to nZVI in which 99 % aniline removal was obtained in 2.5 h containing 61 % of aniline removal through biodegradation and the rest through collective adsorption and biosorption. Maximum adsorption to nZVI was found during the lag phase of cell growth and on reaching log phase adsorption rate declined and removal through biodegradation dominated.