versão On-line ISSN 0378-4738
Bioflocculants produced by Herbaspirillium sp. CH7, Paenibacillus sp. CH11, Bacillus sp. CH15 and a Halomonas sp. were preliminarily evaluated as flocculating agents in the treatment of industrial wastewater effluents. Industrial (1 local chemical-industry and 2 textile-industry: Biavin 109-medium blue dye and Whale dye) effluent (9 mℓ) containing various heavy metals was vortexed with 1 mℓ of bioflocculant in a 25 mℓ test tube. One mℓ of water (Millipore Elix purification system, 17 megaΩ) was substituted for the bioflocculant in the control. After 5 min, the heavy metal concentrations, the microbial population and the turbidity of the top layer of the industrial effluent were determined using ICP-OES, spread-plate technique and a turbidity meter respectively. The flocculating activity was calculated based on absorbance at a wavelength of 550 nm. Bioflocculants produced in this study were capable of removing several heavy metals from industrial effluents simultaneously and effectively. This was significant (p < 0.05) when applied to Biavin medium blue dye, with 95% of Cr2+ and 94% of Ni2+ removed by the presence of bioflocculants. Bioflocculants also removed almost all of the bacteria and reduced 50-80% of the turbidity of the chemical effluent sample, simultaneously. Bacterial bioflocculants may provide an alternative means of treating industrial wastewater resulting in environmental and economical benefits. However, our findings suggest that the treatment of industrial effluents using bioflocculants might be effluent-dependent. In order to explore the potential of bioflocculants in the treatment of industrial effluents, a preliminary study to determine the optimal conditions is crucial.
Palavras-chave : bioflocculant; heavy metals; industrial effluent; flocculating activity; bacterial removal.