Effective removal of microcystins using carbon nanotubes embedded with bacteria

Adsorption of microcystins (MCs) by carbon nanotubes (CNTs) and clay materials was studied. Compared with various clays tested, CNTs showed a much stronger ability to adsorb MC-RR and LR that were two typical types of microcystins found in China. At initial 21.0 mg/L of MC-RR and 9.5 mg/L of MC-LR in solution, the adsorption amounts of MC-RR and LR by CNTs were 14.8 and 6.7 mg/g that were about five times higher than those by the clay materials of sepiolite, kaolinite and talc, etc. In the presence of CNTs and the bacterial Ralstonia solanacearum that was firstly isolated and used for the biodegradation of MCs by the authors, a remarkable removal of MCs from water were observed. The mechanism was that CNTs could absorb large amount of both MCs and the embedded R. solanacearumn so that, even when diluted by a large amount of water, the concentrations of both organic pollutants and the added bacteria could be largely enhanced on the surface of CNTs where a concerted biodegradation reaction was effectively conducted.This finding could be important for the further development of practical techniques to eliminate MCs from polluted drinking waters.