Consortium of Higher Aquatic Plants and Microalgae Designed to Purify Sewage of Heavy Metal Ions

We selected higher aquatic plants (HAP) and microalgae possessing a high sorption capacity in respect to heavy metals to form a consortium designed to purify contaminated aquatic ecosystems. Accumulation of heavy metals Cd2+, Cu2+, Pb2+, and Zn2+ was investigated in plants Pistia stratiotes, Elodea canadensis, and Lemna minor and green microalgae Chlorella vulgaris D'D'-2, Ankistrodesmus sp. D'I-1, Chlamydomonas reinhardtii D'-4, and ScD mu nD mu dD mu smus quadricauda D'-1. It was found that intense accumulation of metals occurs in cultures of HAP Pistia stratiotes and Elodea canadensis. These plants are macroconcentrators of zinc, lead, and copper and microconcentrators of cadmium. Out of the examined cultures of microalgae, effective bioaccumulators of heavy metals were C. vulgaris D'D'-2 and Ankistrodesmus sp. D'I-1. It was shown that heavy metals are selectively taken up from the medium in the series Zn2+ > Cu2+ > Cd2+ > Pb2+. In order to produce a consortium of higher aquatic plants and microalgae for purification of polluted aquatic ecosystems, we investigated interaction of HAP P. stratiotes and E. canadensis with microalgae C. vulgaris D'D'-2 and Ankistrodesmus sp. D'I-1 in the course of their cocultivation. Neutral relations were detected between the cells of microalgae C. vulgaris D'D'-2 and Ankistrodesmus sp. D'I-1 and HAP E. canadensis. At the same time, the cells of Ankistrodesmus sp. D'I-1 and HAP P. stratiotes formed a symbiosis. Microscopic examination showed numerous points where the cells of microalgae Ankistrodesmus sp. D'I-1 were attached to the roots of P. stratiotes plants. We tested an opportunity to employ the association between P. stratiotes and Ankistrodesmus sp. D'I-1 for purification of simulated wastewater polluted with heavy metal ions. This consortium proved to be capable of eliminating contaminants from the sewage, reducing their level in the sewage to standard values, and active accumulation of heavy metal ions.