Abstract
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 m.) containing various heavy metals was vortexed with 1 m. of bioflocculant in a 25 m. test tube. One m. of water (Millipore Elix purification system, 17 megaĦ) 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 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.
Highlights
Heavy metal pollution is a significant environmental problem
The current study investigated the efficiency of bioflocculant activity in removing suspended solids, heavy metals and bacteria, and in reducing the turbidity of 3 different types of industrial wastewater effluents
Gong et al (2008) demonstrated that bioflocculants produced by Serratia ficaria were able to remove the colour and chemical oxygen demand (COD) of pulp effluent more effectively than traditional chemical flocculants
Summary
Heavy metal pollution is a significant environmental problem. To ensure environmental pollution control, removal of toxic heavy metals from industrial wastewaters is essential (Guangyu and Thiruvenkatachari, 2003). Biological materials or dead bacterial cells (Zheng et al, 2008), algae (El-Sheekh et al, 2005), protozoans (Rehman et al, 2008), yeasts, fungi (Guangyu and Thiruvenkatachari, 2003) and plants (Heredia and Martin, 2009) have been shown to play significant roles in heavy metal removal and recovery. Bioflocculants contain various organic groups, such as uronic acids (containing a carbonyl and a carboxylic acid function) (Aguilera et al, 2008; Lu et al, 2005; Wu and Ye, 2007), glutamic and aspartic acid in the protein component (Dignac et al, 1998) or galacturonic acid and glucuronic acid in the polysaccharide component (Bender et al, 1994), which are responsible for binding metals
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