Bioflocculants of Chlamydomonas reinhardtii were investigated under axenic conditions. C. reinhardtii was found to produce significant amounts of bioflocculants. Flocculating activity by C. reinhardtii began in the linear phase of growth and continued until the end of the stationary phase. The highest flocculating efficiency of the culture broth was 97.06%. The purified C. reinhardtii bioflocculant was composed of 42.1% (w/w) proteins, 48.3% carbohydrates, 8.7% lipids, and 0.01% nucleic acid. The optimum condition for bioflocculant production of C. reinhardtii was as follows: under temperature of 15°C to 25°C, pH 6-10 and illumination of 40-60 μmol photons m −2 s −1 . The bioflocculants produced by C. reinhardtii showed maximum activity in pH ranges from 2 to 10. The flocculating activity was significantly enhanced by the addition of CaCl 2 as a coflocculant at an optimal concentration of 4.5 mM.
Capability of three species of aquatic macrophytes to remediate pentachlorophenol (PCP)-contaminated sediments starting with initial concentration of 2,000 lg kg -1 dw (dry weight) was investigated. Negative effect of PCP on the plant growth, chlorophyll contents and root activities (p [ 0.05) of the three species of aquatic macrophytes during remediation was not observed. PCP removal was significantly enhanced in the phytoremediated sediments in comparison with the control sediments after 90 days treatment (p \ 0.05), and the removal rates of PCP in the sediments planted with P. communis Trin, T. orientalis and S. validus Vahl were 90.35 ± 0.03, 99.23 ± 0.02 and 99.33 ± 0.01%, respectively, while the rate was 29.87 ± 0.05% in the control sediments. Bioaccumulation by three macrophytes was confirmed; the maximum PCP contents in the roots of P. communis Trin, T. orientalis and S. validus Vahl were 419.50 ± 0.71, 1,833.33 ± 7.37 and 2,090.00 ± 2.65 lg kg -1 at the 30th day, respectively. In conclusion, P. communis Trin, T. orientalis and S. validus Vahl may act as promising tools for the PCP phytoremediation in aquatic environment, especially S. validus Vahl.
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