Development of an algal treatment system for selenium removal: Effects of environmental factors and post-treatment processing of Se-laden algae

Publication date: Available online 6 November 2018Source: Journal of Hazardous MaterialsAuthor(s): Fang Liu, Jung-Chen Huang, Chuanqi Zhou, Wenqiao Gao, Shaofeng Xia, Shengbing He, Weili ZhouAbstractIn developing an algal treatment system, selenium (Se) removal efficiency by Chlorella vulgaris was evaluated under various conditions such as Se concentration, algal density, temperature and pH. A maximum removal efficiency plateau of ~90% was observed between 1000-3000 µg Se/L while the tolerance of Se toxicity was found at 6000 µg Se/L. C. vulgaris of 0.75 g DW/L showed the highest removal efficiency (84%), and volatilization was dominant below 1.37 g DW/L. Se volatilization was two times higher at 25 °C than at 20 °C in the first 24 h. Moreover, the highest removal efficiency (77%) was obtained at pH 8.0, compared to 66.5% at pH 6.5 and 40% at pH 10.0. To prevent ecotoxicity, Se laden algae were further burned to ashes or filtered out by Anodonta woodiana. After burning, biomass Se was reduced by 99%, with organo-Se entirely converted into inorganic Se, lowering Se bioavailability. A. woodiana removed 54% of Se in 24 h, leading to Se bioaccumulation in soft tissues, which may serve as dietary Se supplements for human health. Our results suggest the cleanup of Se-contaminated water from either agricultural runoff or industrial discharge could be achieved using an algal treatment system with minimum potential ecotoxicity.Graphical abstract
Source: Journal of Hazardous Materials - Category: Environmental Health Source Type: research