Abstract

PRODUCTION, CHARACTERIZATION AND OPTIMIZATION OF MICROBIAL FLOCCULANT PRODUCING MEDIUM FOR BACILLUS SMITHII AND ITS APPLICATIONS

Aishwarya Mohanan* and S. V. Raut

.

Abstract

A variety of flocculants have been used to aggregate colloidal substances. However, recently, owing to the adverse effects and high costs of conventional flocculants, natural flocculants such as microbial flocculants are gaining attention. The aim of the study was to produce and characterize a bioflocculant from Bacillus smithii and apply it in wastewater treatment and degradation of dye. A mixture of butanol and chloroform (5:2 v/v) was used to extract the bioflocculant. DNSA method and Lowry’s method was utilized for the identification of sugar and proteins respectively. Dyes are often recalcitrant organic molecules that produce a colour change and contribute to the organic load and toxicity of textile industrial wastewater. Untreated effluent from such sources is harmful to aquatic life in the rivers and lakes due to reduced light penetration and the presence of highly toxic metal complex dyes. In this study, bacterial bioflocculants were assessed for their ability to degrade dyes and wastewater as well as reducing the microbial load in untreated wastewater. The bacteria were isolated from a wastewater, air and soil sample and identified using Vitek machine. Six bacterial isolates were taken from these samples. The flocculating activities of the bioflocculants produced by these isolates were characterized. The yield of 6 trial of isolate 6 was found to be 96.05% yield which is highest yield as compared to other studies and 4 trial of isolate 6 was found to be 94.88% yield which is another highest yield of bioflocculants. The effect of cations, flocculation inhibition assay and bioflocculant concentration on the removal of dyes and microbial load was also determined. According to the findings of the present study, bacterial bioflocculants were composed of sugars and proteins varying quantities. The bioflocculants were effective to varying degrees in removing the dyes in aqueous solution and also in removing, treating and purifying the wastewater. concentration of bacterial bioflocculants. The optimum pH for the flocculating activity was observed between 6 and 9. The best flocculating activity was observed at 28◻𝐶. Divalent cations such as NaNO3 and D-Glucose improved the flocculation while salts such as K2HPO4, CH2COONa, and Na2CO3 showed less amount of inhibition. The findings of this study strongly suggest that microbial bioflocculants could provide a promising alternative to replace or supplement the physical and chemical treatment processes of river water.

Keywords: Bacillus smithii, Bacterial bioflocculants, removal efficiency, wastewater, dye degradation, 96.05% yield.