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Macrophyte plants will remove heavy metals from water

Macrophyte Plants Will Remove Heavy Metals from Water
Nano-particles of a photocatalyst Credit: SUSU
Scientists at South Ural State University developed an integrated system for ecological purification of wastewater, recommended for enterprises of the industrial agriculture.

Industrial agriculture notably affects the environment. Agriculture and its industrial enterprises for product recycling produce a considerable amount of organic wastes which quickly decompose and emit toxic substances. Wastewater of these enterprises require special approaches for treatment and disposal of wastes.

Integrated approach and ultrasound application

Scientists at South Ural State University elaborated a unique project of a system for eco-treatment of wastewater from agro-industrial enterprises using constructed wetlands and hybrid technologies based on hydrodynamic cavitation and photocatalysis, targeted at saving such a vitally important resource as water.

"In order to reduce the impact on the environment, agro-industrial complexes should be equipped with modern systems of biological purification of wastewater with water return for process needs. Uniqueness of the elaborated project is in using the integrated approach for water treatment. We propose a module scheme which is going to be common for any agro-industrial enterprise," says one of the authors of the project, Doctor of Sciences (Engineering), Professor Irina Potoroko.

The first stage of purification intends for wastewater treatment using hydrodynamic cavitation. This will allow destroying complex compounds of organic residuals and single out heavy metals.

"Organic compounds, for example, wastes of diary or meat processing industries, get into the water. They can capture heavy metals and harmful components and hold them tight. The proposed approach on the basis of hydrodynamic cavitation provides changes in the aqueous system for an efficient application of the second stage of treatment, in which we use constructed wetlands."

Sponge plants

Constructed wetlands and systems similar to them are used for removal of organic substances, heavy metals and suspensions out of industrial and storm wastewater, agricultural wastewater, etc. Macrophyte plants are efficient for removal of heavy metals and other pollutants.

"We have already got experience in purification of surface wastewater from industrial enterprises of mining industry. When purifying drainage water at the constructed wetlands, we can use reed mace, water hyacinth and other plants. Macrophyte plants actively remove both organic pollutants (phenols, oil and petroleum products, chlororganic compounds, herbicides, surface active agents) and heavy metals out of water. For example, duckweed takes quite active part in removing copper out of wastewater. The main difficulty is in selecting plants for a certain object," explains Director of the SUSU Institute of Architecture and Construction, Dmitrii Ulrikh.

As a rule, constructed wetlands are man-made structures designed for certain objects. At the moment, scientists of SUSU's Institute of Architecture and Construction are facing the task of selecting the plants which will be efficient for purification of wastewater from enterprises of the agro-industrial complex.

Innovative method of photocatalysis

A number of pollutants get barely removed or get removed insufficiently. They are pesticides and products of plants' metabolism; generally, they are everything connected with the use of fertilizers of a quite complex structure. The pollutants remain in the water and get to water bodies. For final purification, SUSU scientists proposed the method of photocatalysis, at which these pollutants get completely dissociated into carbon dioxide, water and other elementary harmless substances.

"We propose using the innovative method of photocatalysis, at which nano-structured particles of the catalysts are in an inert granule. Such a granule is big and heavy; it can be easily extracted from purified water and used again. And particles possess high catalytic activity due to being of a nano-size," says Vyacheslav Avdin, Dean of the Faculty of Chemistry at the SUSU Institute of Natural Sciences and Mathematics.

Nano-particles of a photocatalyst can be selected and their properties can get adjusted. Right now, the goal of the scientists of South Ural State University is to modify the particles of photocatalysts for specific pollutants.

The unique integrated project elaborated by SUSU scientists will allow developing and choosing efficient methods of wastewater treatment, taking into account the nature of economic activity at enterprises of the agro-industrial complex, in order to recover the disturbed aquatic ecosystems. This will allow minimizing the risks of secondary pollution and help saving the environment.

Research in the sphere of ecology is one of the three prioritized directions in development of research and educational activity at South Ural State University together with digital industry and materials science. Implementation of ecology-related projects is targeted at forming a favorable ecological environment in Chelyabinsk and the region. The successful experience of SUSU scientists can be applied in other regions of Russia with a difficult ecological situation.

Provided by South Ural State University